Tag: horticulture

Urban political ecology contains a political program “to enhance the democratic content of socio-ecological construction by identifying the strategies through which a more equitable distribution of social power and a more inclusive mode of environmental production can be achieved” . As a result, urban politics play a key role in this emancipatory political project. At the forefront of any radical action must be considerations of how social actors can take control of the production of urban space “in line with the aspirations, needs and desires of those inhabiting these spaces” and questions of “whose nature is or becomes urbanised” . While gardening may present revolutionary or transformative approaches to urban spatial production, blind enthusiasm for the potential of these projects does not engage the essential questions of where, how, and with whom the gardeners’ work is developed. Gardens reflect and reproduce different boundaries of enclosure, inclusion and exclusion – both with participants and material, spatial land tenure relationships – within neighborhoods and within movements. Decisions on the construction of these boundaries shape the character of a garden and the role it will play in social change. Recognizing the multiple meanings and representations of ‘community’ in urban agriculture, Pudup calls for the adoption of the term ‘organized garden project’ instead of community garden. Organized garden projects refer to specific places,vertical farming in shipping containers geographical spaces not typically used for growing agricultural products that are cultivated by organized groups of people with collectively defined goals.

One such goal is securing tenure arrangements that allow gardeners to continue their projects in the manner they desire, whether that be through roving gardens moving from vacant lot to vacant lot, acquiring the use of public parks and public programing to support urban agriculture, or using gardens as a political tool in resisting development and gentrification. Gardeners recognize that their tenure strategies are bounded or to some degree shaped by contemporary property relations. Their assessment that property relations are a determining dynamic for the future of their gardens is acute. Many gardeners also contend that they are active participants in shaping the property relations that may determine the fates of their projects. Gardeners stress their projects are making a real impact on how local municipalities are embracing urban gardening as land use, how residents view the use of land for food production, and how gardening can challenge the priority of land value for development. I term the process of decision making gardeners that take in manifesting a land access strategy landing. Landing is a process of creating closure, when utopian desires are enacted on the land and preexisting property relations. Through landing gardeners recreate old or develop new socio-spatial relations, setting direction, and foreclosing on other possibilities if only for the moment. In analyzing organized garden projects in the San Francisco Bay Area, this dissertation explores two central themes: the political project to gain secure land tenure for the future of urban agriculture and the production of practices and narratives of property and urban space through garden projects. The first theme stems from the argument by gardeners and garden advocates that contemporary urban agriculture projects should become a permanent part of US cities. Gardeners are acutely aware of the lack of land tenure security on both public and private land due to the politics of ownership. A 1996 survey conducted by the American Community Gardening Association found that of urban gardens in thirty eight cities in the US, only 5.3% were owned by the gardeners or in permanent land trust .

The desire and commitment amongst garden advocates, spurs the questions: what form of garden are being promoted as the ideal for permanent urban agriculture, and what are the potential material and discursive consequences of these forms? The second theme explores how gardeners are engaged in reimagining the production of urban space and property as a dominant capitalist institution. In doing so, it also examines the tensions among differing cultures within urban agriculture that participate in utopian projects of recreating contemporary cities in more just and sustainable ways. These projects exist within conditions of possibility produced by urban development politics and also shape, through rhetoric and practice, a terrain of political possibility for change. Analyzing the ideologies, institutions, and practices of property promoted by differing garden projects can shed light on the potential contributions of these projects to transformative urban and food politics.Urban agriculture has had a presence in US cities since the 1880s, with several periods of popularization and growth . However, with the reemergence of gardening as a strategy in the community food security, food justice and food sovereignty movements, scholars debate how and if this new wave of urban agriculture can contribute to radical urban transformation. Historically, gardens served as a tool to improve urban conditions, especially during times of economic or social crisis when small patches of cultivation expanded to city or nation-wide projects . Urban agriculture has served as a social safety-net by feeding low-wage workers and subsidizing the social reproduction of workers during these times of crisis . Today’s social movements engaged in urban agriculture focus on lack of physical access to healthy food, racism in US food systems, and gaining popular control of the food system.

Self-provisioning through urban food production has been embraced as a means to address these social problems. In addition to improving food resources, scholars assert that urban agriculture contests dominant logics about the best use of urban space. McClintock argues that urban agriculture exists in tension with capital simply by putting underutilized land to use in the production of food . Mares and Peña agree that urban agriculture projects are forms of resistance to commodification of space, asserting that the use of spaces for agriculture that would gain higher rents for other uses . In highlighting that use-value is prioritized over exchange value, scholars are reviving Lefebvre’s arguments about the resistance potentials of urban social movements. Urban agriculture can raise questions about who deserves access to urban land and urban development processes. For Lefebvre, abstract space, like Marx’s abstract labor, contains the seeds for differential space, the seeds for resistance. In describing exchange-value coming to overpower the mode of production in the processes of urbanization, he saw the potential for urban revolution in the struggle for the ‘right to the city’ . To Lefebvre, the entire world was becoming the urban as the production of space became a more dominant force than industry. ‘Urban’ carried the prioritization of use-value as space became “an inscription of time promoted to the rank of a supreme resource” . Yet, within his critique of growing urban hegemony, Lefebvre proposed the concept of the right to the city, a right that is not bound to the city,hydroponic vertical farming systems but is better described as a right to “a place in an urban society in which the hierarchical distinction between the city and the country has disappeared . This can be read in the increasing financial investment in farmland nationally and abroad; for example in 2010 the pension fund TIAA-CREF invested $2 billion in farmland in the US . In the face of growing inequity in cities dominated by neoliberal practices, critical urban theorists and community activists have once again returned to the framework of ‘right to the city’ proposed by Lefebvre in 1968 . The concept of right to the city connects both the just distribution of material resources and the democratization of the processes of urbanization. Urban gardening that prioritizes the use of city land for food production, cultural engagement and community building can both challenge the dominant logics of development and also provide the seeds for coalition building under the banner of ‘right to the city’. Gardeners in the Bay region argue that their work does this by demanding a say in urban governance. At the same time gardeners also question if their work contributes to urbanization that continues to benefit capital’s interests and does little to empower marginalized communities. Gardening led by non-profits can be read as part of the contemporary trend where third sector organizations have proliferated and become institutionalized as the appropriate site space for the formation of citizen subjects . Social change enacted through volunteerism and non-profit groups, as opposed to state agencies, can have undemocratic consequences of limiting who is invited or able to participate in decision-making processes, such as those of governance and production of urban space. Furthermore, gardeners are also aware that their work may be and is, as illustrated in several examples in this study, aiding in the processes of gentrification, a significant issue in the region. Urban gardening has become increasingly popular at the same time that discourses of sustainability have gained increasing political influence within US cities. Sustainability policies and discourses have opened possibilities for urban improvement projects such as gardening under the umbrella of larger plans for continued urban development and capitalist accumulation .

Such reasoning has given scholars and activists hesitancy in their desire to view urban agriculture projects as materially or discursively transformative land use practices. The potentials of radical land use through gardening must be contextualized in the actually existing practices of the social movements in which gardeners participate, i.e. contemporary food movements. Some scholars have argued food politics has largely been de-politicized and individualized as neoliberalism impacts food and agricultural activism . Other scholars have cited gardens as a site of “against and beyond”3 politics both challenging contemporary capitalism and building new forms of social relations . This dissertation engages the question of how gardeners frame the politics of possibility. Although all the gardeners interviewed in this study were committed to food movements as discussed in Chapter 3, the politics and urban utopian imaginaries of the gardeners vary. One thread of politics that has a strong presence in organized garden projects is what Dixon calls “the anti-authoritarian current” articulating the work of “against and beyond”. Anti-authoritarian politics, the politics of “another world is possible”, seek to create political spaces beyond party building used by liberals, social democrats, and Leninists alike, as well as beyond non-profit dominated spaces or isolated affinity group organizing . Activists work against domination, exploitation, and oppression through bottom-up organizing strategies to create new social relations and forms of social organization beyond contemporary models, thus ‘prefiguring’ more desirable practices . “Against and beyond” resists a dichotomy of oppositional or alternative politics that emphasizes either changing contemporary systems or creating new ones, seeing the potential in prefigurative politics in spaces like the land politics of urban gardens. Hegemonic power structures, like the dichotomy of private and public property, while dominant are not singular, complete, or without internal contradiction . The power of hegemony must be continually renewed and defended through multiple cultural and material processes . Thus, I read gardens as an essential site to understand contestations of the institution of property. Althusser described the process of subjection as part of the processes of securing hegemonic power . Through practices ideology is made material; when these practices are repeated, ritualized and institutionalized, we can observe the form of ideological state apparatuses. Ideology functions to constitute individuals as subjects through a process of interpellation. Simply put, the individual is hailed, recognizes the call, and freely submits to her subjection. The subject not only recognizes herself in the interpellation, but also recognizes that this is an accurate representation of reality, seeing others as subject. Gardeners, within and beyond food movements, seek to create subjectivities of possibility, thus creating conditions of possibility for intersubjective change. Althusser recognized that the processes of interpellation and the development of ideology are simultaneous processes or “things that happen without any succession” . This mechanism permits the reproduction of the relations of production and resulting social relations of oppression, resistance, or multiple forms in and outside of hegemonic social relations depending on your reading . Thus when one gardener calls for the need for more ‘vandals’ as subjects called to create more food through guerilla tree grafting, they recognize subject formation as part of a broader process of engendering ideology challenging the dominance of private property’s boundaries and production urban environments that favor possibility, both oppositional and alternative, through gardening. Political projects, like the one of the vandal, are also not singular, complete or without internal contradiction. Analyzing the internal contradiction of political projects within particular spatiotemporal contexts can open possibilities for alternatives .

Following Mutharika’s departure from the UDF in 2005, the president engaged in an aggressive campaign to attract support across ethnic and regional divisions, an effort that was highly successful as indicated by the broad-based electoral support he received in the 2009 election in which he defeated the second-place candidate, John Tembo, by a margin of 66% to 31%. The shifting political landscape, however, meant that traditional ethnoregional alignments were temporarily upended.8 Second, Malawian parties lack the local level networks that allow machine-based parties in other parts of the world to identify core and swing voters at the village or neighborhood level. Political parties in Malawi function primarily at the national level with weak or nonexistent formal structures at the local level . This was particularly true of Mutharika’s DPP, which, having been formed in the aftermath of the president’s 2005 departure from UDF, initially lacked even basic local-level infrastructure. While individual politicians, such as parliamentarians, no doubt maintained their own informal networks at the local level, the challenge of distinguishing partisans from non-partisans based on observable markers would have been formidable. Given these informational limitations we expect the subsidy program to be largely untargeted with respect to ethnicity and party support at the individual level within villages . The analysis of subsidy targeting and its political effects employs data from two waves of a panel survey of rural Malawians in 122 villages clustered in three districts: Rumphi, Mchinji, and Balaka. Each administrative region of Malawi is represented in the study, as are the three major ethnolinguistic groups .

The surveys are part of the Malawi Longitudinal Study of Families and Health ,danish trolley which began in 1998 and aims to understand how villagers cope with health challenges like HIV/AIDS. In each district, the MLSFH used a cluster sampling strategy across selected census enumeration areas. A random one-in-four sample of women of reproductive age and their husbands was drawn from villages to yield a target sample in 1998 of 1,500 women and their husbands . The resulting sample in 1998 included 1,532 evermarried women aged 15-49 and 1,065 of their spouses. In 2004, the MLSFH added a sample of 984 adolescents aged 15-24, and during the 2008 round a sample of 549 parents of respondents in earlier MLSFH rounds was added . New spouses of MLSFH respondents were also added in each wave. Though the original sampling strategy in 1998 was not designed to be representative of the rural population in Malawi, the sample’s characteristics are very similar to those of the rural population interviewed by the Malawi Demographic and Health Surveys that covered nationally representative samples . Between the two rounds studied here, 1,016 respondents were lost to follow-up;9 thus, though the 2008 round included a sample of 3,909 respondents and the 2010 sample included 3,786 respondents, our analysis includes only those 2,851 respondents who were interviewed in both 2008 and 2010. The analytical sample in this paper drops to 1,846 when we remove study participants whose responses on standard questions are inconsistent between the 2008 and 2010 waves and when responses are dropped because of missing information on key variables.We augment the individual-level panel data with village-level data collected through a survey of village headmen in the 122 research villages conducted in 2008.The first step in the analysis is to test for evidence of targeting.

While the results from this analysis are interesting in their own right, the primary goal is to identify factors that might confound the analysis in the next section of the subsidy’s effects on voters’ political preferences. To examine targeting in our survey area, we draw on a question on the 2010 survey that asked respondents whether they had received a voucher for fertilizer or seeds in each of the previous two years. We focus on those who received the subsidy in the 2009/10 growing season, which immediately preceded the second wave of the survey. The data show that 73.7% of respondents received the agriculture subsidy in 2009/10. Respondents in the three district clusters were about as likely to receive the subsidy, with 74.6% receiving it in Rumphi, 78% in Mchinji, and 68.2% in Balaka. The independent variables for the targeting analysis come from the 2008 survey unless otherwise specified. Our key independent variable measures party support according to responses to a question that asked, “Do you feel close to any particular political party?” Those who answered affirmatively were then asked which party. In total, 53.2% of the sample registered support for a party, with the largest share expressing support for the incumbent party, DPP, and smaller shares indicating support for one of the opposition parties . The distribution of party support in our survey area mirrors national-level trends found in the 2008 Afrobarometer survey.We also include a measure of whether respondents are “minority partisans” in their villages, supporting a party other than the party thought to be supported by most people in the village. We test for targeting along ethnic lines, given the centrality of ethnic divisions and ethnoregional favoritism in Malawi’s political history . We include a dummy variable for Lomwe respondents and also include dummies for Malawi’s other major ethnic communities, the Tumbuka, Chewa, and Yao. In our survey area, these four groups make up 93.9% of the sample. We also include an indicator of whether respondents come from minority groups within their villages, using data from the headmen survey on the majority ethnic group at the village-level.

Following Pan and Christiaensen , who found that local elites in Tanzania tended to capture the benefits of a similar subsidy program, the analysis includes several measures of social stature to test whether those in leadership positions within their communities may have been more likely to benefit. We include indicator variables measuring whether respondents were members of the Village Development Committee, the Chief’s Council, or the District Development Committee in 2008. To test whether the program benefitted the most needy, we include multiple measures of socio-economic status. First, we include a measure of wealth constructed as an index of household asset ownership.We include three measures of whether respondents experienced negative economic shocks in the year prior to the 2009/10 growing season. These relate to: 1) loss of income, 2) poor crop yields, or 3) the death or serious illness of an adult member of the household. Though only the second measure explicitly references an agriculturally related loss, all three measures capture severe shocks that make households particularly vulnerable to food insecurity. We also include a measure of farm size and standard demographic measures: age, education, and whether the household was headed by a female. We use logistic regression to examine individual-level subsidy targeting,vertical aeroponic tower garden and include village fixed effects to account for village-level differences that might affect access to coupons, including politically-motivated targeting across villages. We cluster standard errors by household because in some cases multiple respondents were interviewed in the same household. Table 1 shows the results and Figure 1 plots the marginal effects of each variable holding other covariates at their mean values. Figure 1 indicates that, conditional on village, the subsidy was not targeted with respect to party preferences or ethnicity in our survey area. Supporters of the incumbent party in 2008 were no more or less likely to benefit from the subsidy program in 2009/10 . Likewise, opposition party supporters were no less likely to receive the benefit, nor were individuals who were minority partisans in their villages. The results also show that, relative to members of smaller ethnic groups , respondents from Malawi’s major ethnic communities were no more or less likely to receive the subsidy during the 2009/10 season. We also entered each ethnic dummy variable individually in additional tests and found no evidence of ethnic targeting in these specifications. Likewise, we find no evidence of discrimination against individuals from minority groups at the village level. Consistent with findings by other scholars , we fail to find evidence that Malawi’s AISP effectively targeted those with greatest need, despite the program’s stated goal of reaching those most at risk for food insecurity. Our results show that neither poorer respondents, nor those with smaller land holdings were more likely to receive the subsidy. Moreover, respondents who experienced an economic shock related to loss of crops, livestock or income in the previous year were no more likely to benefit from the AISP than those unaffected by such income shocks.

Further, households that suffered the death or serious illness of an adult in the previous year were actually less likely to receive the input subsidy. Together, these results suggest the program did not successfully target those with greatest need – poor, smallholder farmers threatened by food insecurity. The results on demographic factors show that age and education were unrelated to receiving the subsidy. We find negative and significant gender effects. In our survey area, female headed households were 10.4% less likely to receive the subsidy. Given that the models control for a wide range of factors that might affect levels of need, social stature, and economic shocks, the finding reported here suggests that female heads of households were less likely to benefit from the program as a result of gender discrimination rather than other factors that might be correlated with gender.Finally, the results indicate that members of district and village development committees or chief’s councils were not statistically significantly more likely to benefit from the program. To answer this question we examine trends in party support among recipients and non-recipients across the two survey rounds. Our measure of political preferences – taken from questions on the 2008 and 2010 surveys that asked respondents whether they “feel close” to any party – sets a high threshold for finding a positive effect. Similar studies typically use measures of vote choice , which are likely to be more fluid and potentially subject to influence by anti-poverty programs. Our measure probes deeper connections between voters and parties, and is therefore less likely to be influenced by short term changes in government policy.Moreover, Zucco’s study of the political effects of a conditional cash transfer program in Brazil found evidence of an effect only on vote choice and not on partisanship. Thus, the measure of party support available in our survey data in all likelihood biases against finding a positive effect of the subsidy on political preferences. A second challenge relates to the nature of the treatment effect we seek to estimate. Sociotropic theories of economic voting have found that voters may punish and reward incumbents based on the overall performance of the economy . If voters in Malawi base assessments of the incumbent on aggregate outcomes – rather then their own personal welfare – the subsidy program may represent a treatment that was received by all Malawians. Studies have shown that the AISP contributed to reduced food prices in Malawi, indicating that Malawians may have benefited indirectly even if they did not receive subsidy coupons . These factors also bias the analysis against finding a connection between individual measures of subsidy reception and party support. Despite these challenges, the data suggest that the subsidy did affect political preferences. Table 2 compares the increase in support for the DPP between 2008 and 2010 among those who did and did not receive the 2009/10 subsidy. Among non-recipients, the percent expressing support for the DPP rose by 3.4%, from 34.8% to 38.2%, while for those who did receive the subsidy, the increase was approximately three times larger: 9%, from 35.3% to 44.3%. Thus, receiving the subsidy in 2009/10 is associated with a 5.6% increase in DPP support. While these results are suggestive of a treatment effect, there is, of course, the possibility that subsidy recipients differed from non-recipients in some important ways, and these underlying differences – not the subsidy – account for the greater increase in DPP support among recipients, relative to non-recipients. We are reassured by the results from the previous section, which showed that the 2009/10 subsidy was largely untargeted in our survey area, particularly with regard to prior party support and the primary demographic factor – ethnicity – that has traditionally been associated with party support in Malawi. Nonetheless, differences might remain that could confound the treatment estimation.

The range of average landholdings across household groups is larger in Nicaragua and El Salvador than in Honduras and Guatemala . 5 In part, these differences reflect the criteria that were used to classify rural households; however, both the average landholdings and the criteria used to construct our household groups also reflect differences in access to land in the four countries. What constitutes a large holder household in Nicaragua is not the same as in Guatemala, for example.In addition to being heterogeneous, rural households exhibit diversified income sources, technologies, and demands. The same rural household commonly participates in multiple activities and receives income from various sources. Policy shocks that directly affect one activity are transmitted to others within the household as well as to other households in the rural economy. In most household groups, the share of household income from agricultural and livestock production is less than 50% and for some groups it does not reach 25%. Nearly all groups obtain around 50% of their income from wages, the majority of which are non-agricultural. Even commercial households depend heavily on wage labor for their income. Agricultural and livestock production in each household group is also diverse. For example, in Nicaragua, medium commercial households acquire a little less than one third of their total value-added from the production of basic grains, and the other four producing groups obtain between 16% and 24% from this activity. Livestock accounts for between 27% and 52%,raspberry cultivation pot depending on the household group. The shares of traditional export crops are less than 10% of total value added in all groups except large commercial households.

Production of non-traditional crops represents more than 10% of total value added in all household groups, and non-agricultural production accounts for more than 10% in all but low-education landless households and large commercial producers . Similar levels of diversification are found in the other three countries. In all groups, the average household participates in multiple income activities, including production, wage labor, and migration. There is evidence of technological diversification, reflected in differences in factor value-added shares in the same activity but across households. In general, family value added shares are smaller in the same activities for large commercial households than for subsistence producers, while market-input shares are larger for commercial producers. Technological heterogeneity across households, like differences in market access, is generally absent from aggregate economy-wide models.To construct the rural economy-wide models, we first used data from the surveys to construct a Social Accounting Matrix for each rural household group. Each of these SAMs could be viewed as generated by a single agricultural household model. The SAMs were then joined together into a rural sector-wide SAM for each country. Nearly all of the information needed to calibrate the corresponding household models and the rural economy-wide models are contained within these SAMs, as explained below. The four rural SAMs are interesting in and of themselves, because they offer a snapshot of individual groups of rural households as well as the linkages that transmit influences of policy shocks among households. The framework of the SAMs is described in appendix B. Each household SAM consists of a set of 44 production activities, 5 factors, government, 9 investment accounts, and three “rest-of world” accounts, including the rest of the rural sector of which the household is part, the rest of the country, and the rest of the world outside the country.

Unfortunately, no single data source provides all of the information necessary to estimate the SAMs. Because of this, data from diverse sources were used to construct a SAM for each rural household group in each of the four countries. The SAMs, together with econometric estimates of remittance elasticities and family value-added shares, were used to calibrate the household models that constitute each DREM. The key data sources for each country include the rural components of the El Salvador Multi-purpose Household Survey of 2003, the Guatemala National Living Standards Survey of 2000, and the Nicaragua Living Standards Survey of 2000. All three of these are nationally representative and provide information on socio-demographic variables, production and inputs, wages, migrant remittances and income from other sources, and expenditures. Anationally representative survey was not available to construct the Honduras DREM; thus, the six rural household SAMs were constructed from two data sources: a survey of rural households conducted by IFPRI-WUR-PRONADERS in 2001-2002 , and a rural household survey conducted by the University of Wisconsin and The World Bank in 2000-2001 . The IFPRI survey covered 376 households and 1066 parcels in 19 cantons, and the University of Wisconsin survey covered 850 households in 26 cantons, mostly in the northern part of the country. We primarily used the IFPRI survey to construct the Honduras household SAMs, because of its greater detail on production costs and consumption expenditures and because it is more nationally representative, as hillside zones constitute 80% of the nation’s land area. The Wisconsin data were used primarily to disaggregate family value added.

The form of each household-specific factor and consumption demand depends on technology and preferences. On the technology side, we assume Cobb-Douglas production functions for each household group and good, in which the exponents are set equal to factor shares in value added, as implied by profit maximization and available from the household SAMs. Consumption demands were modeled using a linear expenditure system with no minimum required quantities , implying that preferences of individual groups are described by a Cobb-Douglas utility function. Budget shares, like factor value-added shares, were calculated from the household expenditure columns in the SAMs. The elasticities of remittance income with respect to migration were estimated by regressing household remittances on the number of family migrants in each household. The solution to the base model for each country determines labor demands in each activity, production, full income and consumption demands for each rural household group, the agricultural wage, migration, and shadow prices of grain in subsistence household groups.This base model is the starting point for carrying out simulations to explore the impacts of CAFTA’s agricultural provisions on rural welfare.Simulations were conducted under three different scenarios designed to explore the impacts of trade policy adjustments, which are depicted in appendix A, on the rural economy of each of the four countries in the short, medium, and long run. The simulation experiments are summarized in table 4. Our simulations are founded on two propositions. The first is that domestic prices of agricultural commodities would decrease by percentage amounts equivalent to the changes in tariffs prevailing prior to CAFTA. The second is that the changes in agricultural prices would directly affect only the producers that market the good in question. That is, subsistence households would not be affected directly by trade reforms,low round pots although they may be affected indirectly, via other rural markets.The extreme or long-run scenario, in which an immediate elimination of tariffs for all agricultural goods is simulated . This scenario illustrates what might occur without transition policies, including gradual removal of tariffs, and with no change in Central American countries’ agricultural exports to the United States. Unlike NAFTA, CAFTA does not call for a reduction in tariffs for white maize. Nevertheless, we include the removal of tariffs on white maize imports in this simulation because it is intended to represent the extreme case and also because there may be some substitutability between white and yellow maize in production and consumption. The intermediate or medium run scenario simulates a case in which there is immediate elimination of tariffs for sensitive agricultural goods whose tariff-free quotasexceeded imports from the United States in recent years, and/or for which the tariff phase-out period initiates during CAFTA’s first year. How to treat maize in this scenario is complicated for various reasons. Although CAFTA differentiates between white and yellow maize, there is some degree of substitutability between the two. However, in our simulations it is not possible to differentiate between yellow and white maize. Most household production in Central America is of the white varieties, but the available data do not distinguish maize by color. Additionally, the decision of whether to include or exclude maize based on the difference between CAFTA quotas and imports depend on the period during which one measures maize imports. This intermediate scenario includes maize liberalization in El Salvador, Guatemala, and Nicaragua.

In these three countries, tariff-free quotas established for the first year of CAFTA significantly exceed maize imports from the Untied States; thus, one would expect a decrease in domestic prices in the medium but not the short run. Maize liberalization is excluded from the intermediate scenario for Honduras, where tariff-free quotas are equal or inferior to pre-CAFTA imports and are small compared with total supply . This scenario also includes the elimination of tariffs for beans and meats in each of the four countries, because a grace period was not negotiated for these products. Finally, rice was included for Honduras, where the negotiated quota exceeds current imports. Finally, the low or short-run scenario simulates a situation in which sensitive products with special safeguards and/or grace periods of 10 years or more are excluded. This scenario excludes liberalization of rice, maize, small livestock, and milk products in each of the four countries. It eliminates tariffs on large livestock and beans in Guatemala, Nicaragua, and Honduras. There are special safeguards and a 15-year phase-out of tariffs on these products in El Salvador. The phase-out period of included products initiates in year 1 and that of excluded products begins after year 5 of CAFTA’s implementation. The exception is low-quality meats in El Salvador, for which the grace period is only three years. The results of these scenarios depend on the design of the scenarios, which reflect pre-reform protection levels and the details of the agreement’s implementation in each country, the linkages among rural households and markets, which transmit the effects of the reforms through the rural economy, the mix of pre-reform production and income activities in each household group and country , and , the model parameters, which shape the responses of rural household production, consumption and migration.The extreme scenario represents a significant shock for the rural economies of all four countries. Its immediate effect is felt in the producer households that sell the affected goods prior to CAFTA. Market linkages transmit the effect from these to the other rural household groups, including landless and subsistence households. Basic grain production falls sharply in almost all cases; however, there are striking differences between countries as well as among household groups within countries . Grain production decreases by 26-30% in Guatemala, 14% in Honduras, and 8-50% in Nicaragua. Supply elasticities for each household group, which can be calculated from the simulations, reflect general-equilibrium adjustments in each country’s rural sector. For maize, these range from 0.26 to 1.15 in Nicaragua, 0.70 to 0.90 in Honduras, and 1.65 to 1.69 in Guatemala. In most cases, the largest decreases in supply are for the grains that were most heavily protected prior to the CAFTA reform: rice in Nicaragua, El Salvador and Honduras and maize in Honduras. Nevertheless, in some cases general-equilibrium effects mitigate the effects of prices changes implied by the elimination of tariffs. This is the case in El Salvador, where the price of maize decreases by 20% under the extreme scenario but maize production falls by 1.4 and 12.2 percent in small and medium commercial households, respectively. This seemingly paradoxical result is explained by the importance of livestock products in this group’s production mix and an even steeper decline in livestock products under this scenario. The changes in basic grain prices do not have a direct effect on subsistence households. However, its impact is transmitted to these households via rural markets, particularly for labor. Implicit or shadow prices of specific basic grains are almost unchanged in El Salvador, but they decrease 0.9-2.8% in Guatemala, 0.5-1.3% in Honduras and 2.1-6.7% in Nicaragua, compared to decreases in commercial prices that range from 15% to 62%. Lower shadow prices of grains accompany decreases in subsistence household incomes. Labor demands on large farms contract, causing a reduction in rural wages in all scenarios.

We assessed differences between habitat types, as in previous studies, and did not detect consistent differences between organic and conventional farms; however, our analysis of the effects of specific farm practices on bats was much more informative . We documented significant overlap in practices between organic and conventional farms included in the study , which may explain why we did not detect strong differences between farm management types that mask the influence of local farm practices and characteristics on bats. We found greater bat activity in natural areas compared to farms,highlighting the importance of conservation of natural habitat patches within intensive agricultural landscapes. This finding is consistent with previous studies in mixed annual cropping systems in the US and vineyards in North America . Our finding that diversity was marginally significantly higher in natural habitat than on conventional farms may be explained by differences in local habitat features. Conventional farms had the least variation within site types, with large monocultures of annual crops and little non-crop vegetation, creating open habitat dominated by T. brasiliensis. Natural vegetation sites comprised a range of vegetation forms spanning mixed riparian vegetation to oak woodlands, offering habitat niches for more diverse species. We found no evidence of differences in species richness between site types,fodder growing system as the same species were usually documented across clustered sites.

However, we did find that bat community composition differed between natural habitat and farms,but not between organic and conventional farms.Our finding that farms with more crop varieties had greater activity of all bat species and clutter-adapted bats is the first evidence that bats respond to herbaceous plant diversity on farms. The effect of crop diversity on bats has not been previously tested, and we are not aware of other studies that have documented effects of on-farm herbaceous plant diversity. Most similarly, a study comparing bat activity between farm field margins planted in mixed grasses and conventionally managed field margins did not find a significant effect on bat activity . In contrast to previous studies, we found no evidence that bat activity was positively correlated with proximity to linear habitat . However, difference in the extent and configuration of linear habitat in European farmlands compared to the CCR may explain why our findings conflict with previous literature. Differences in woody vegetation that would impact environmental clutter did not predict clutter-adapted bat activity. If proximity to linear habitat in- fluenced bat activity, it may have been necessary to monitor at a linear edge and at increasing distance into a crop field. To link our findings of the relationship between crop diversification, bat activity, and insect biomass, we focus on clutter-adapted bats. Our finding that crop diversity was significantly correlated with higher clutter-adapted bat activity and greater biomass of Lepidoptera, and that greater biomass of this important insect prey order was significantly positively correlated with higher bat activity, suggests that crop diversification impacts bats via changes in populations of insect prey .

Farms with higher crop diversity also tended to have more noncrop herbaceous cover and weedy field margins as farms often employed a suite of diversified practices. On-farm vegetative diversity can provide critical insect food and habitat resources that are not found in simple monocultures, increasing insect abundance , and improving foraging habitat for bats. The frequency of pesticide use decreased the biomass of Diptera, and Coleoptera, which account for 20–40% of the summer diet of M. yumanensis and T. brasiliensis, in California , the two most common species in the study region. Higher application rates of pesticides and use of synthetic agrochemicals in conventional systems has been suggested as the mechanism driving increased insect abundance and bat activity on organic farms . Because bat activity increased with crop diversity and activity of clutter-adapted bats increased with Lepidoptera biomass, we suggest that both vegetative diversity and pesticide applications drive changes in insect populations and bat activity. Previous studies also demonstrate a positive correlation between bat activity and insect biomass in pastures, linear habitat, and crop fields in agricultural landscapes and show that bats track and feed on populations of insect pests . Of course, the correlation between bat activity and insect biomass is a two-way relationship. Bats may be attracted to higher quality on-farm foraging areas with greater insect biomass, in turn consuming more insects and suppressing insect population levels on these farms, which may explain why we did not see a correlation between open-space bats and insect biomass.

Despite this two-way relationship between bats and insects, our findings provide evidence that crop diversification and less frequent pesticide use increase insect prey and bat activity on farms. The influence of crop diversification on bat activity does not depend on the amount of semi-natural habitat surrounding the farm. Although a few studies in tropical agroforestry systems have confirmed an interaction between local and landscape scale agricultural intensification , Froidevaux et al. found that the effects of local vineyard management were not dependent on landscape complexity. Moreover, we found that crop diversity is a better predictor of bat activity on farms than semi-natural habitat density. Similarly, Kelly et al. did not find strong effects of seminatural habitat density on bat activity on farms. Bat activity in remnant semi-natural habitat is higher is agricultural landscapes with more semi-natural habitat , but the effects of landscape-scale factors on bat ecology have not been extensively studied in temperate, annual cropping systems .Hedgerows, woodland patches, and scattered trees can support bat conservation in agricultural landscapes . A focus on the importance of structural, woody vegetation to bat conservation reflects species’ specific roosting requirements that are not provided by farms, and the potential for structural vegetation to increase habitat connectivity for species with structure-bound ecologies. The conservation of woody vegetation is undoubtedly important to the long-term conservation of bats in agricultural landscapes. However, because the addition of woody, perennial vegetation is often not a feasible management strategy for growers in intensive agricultural systems, we suggest that including a complementary focus on improving the quality of bat foraging habitat offers additional management options in agricultural landscapes. Intensive agricultural systems provide inconsistent food resources to bats, whereas the maintenance of natural habitats can help to ensure stable food resources . Similarly, diverse on-farm and within-field vegetation can help to ensure consistent food resources for bats without negatively affecting production practices or increasing pest problems. The addition of herbaceous plant diversity can be designed through species selection and timing of planting to support desired insect communities . On-farm plant diversity can improve pest suppression, enhance populations of beneficial insects, reduce crop damage, and increase crop yields .Twenty-five years after the publication of the first IPCC Assessment Report, it is instructive to step back and ask what we have learned about the economic impacts of climate change to the agricultural sector, not just from a technical standpoint, but from a conceptual one. California is an ideal focus for such an analysis both because of its strong agricultural sector and proactive climate policy. After passing the 2006 Global Warming Solutions Act,chicken fodder system the state has sponsored research to complete three climate change assessments, with the fourth assessment report in progress at the time of submitting this paper. This effort to study adaptation appears to be relatively more prolific than in many other global sub-regions, particularly over the past decade .

Assessing adaptation potential — the institutional, technological, and management instruments for adjusting to actual or expected climatic change and its effects — represents an important turning point in the climate impacts literature. The important role of responsive decision-making by farmers and institutions is recognized for the first time as the key ingredient to dampening the effects of climate change . Adaptation was simply mentioned as an optimistic afterthought in earlier studies, which suggested that agriculture would fully or mostly adjust in the long term — although there was sparse detail on how it would do so . When adaptation was directly included in the modeling framework, economists found that the estimated welfare damages from climate change documented in previous studies declined . In colloquial terms, this is a shift from modeling the “dumb” farmer to modeling one with reasonable economic agency. There are four key concepts linked to the idea of adaptation: vulnerability, adaptive capacity, economic welfare, and economic efficiency. In the IPCC literature, adaptation is connected to the foundational concept of vulnerability, defined as the propensity for agricultural systems to be affected by future climatic changes . Vulnerability can also be defined endogenously as the ability of farmers and institutions to respond and adapt to, and recover from such changes . This latter definition is synonymous with the concept of adaptive capacity, or the ability of a system to moderate potential damages and take advantage of adaptation and mitigation opportunities to reduce vulnerability of the system to climatic changes . Adaptation dampens welfare losses caused by climate change. The relationship of adaptation with vulnerability is more complex, and better represented as that of trade-offs. For example, changing the crop mix in favor of high value crops may reduce vulnerability to water scarcity, but it may increase vulnerability to heat tolerance. Finally, the concept of efficient adaptation has been defined as a situation where the costs of effort to reduce climate-induced damages is less than the resulting benefits from adapting . Given the central role of farmer and institutional responsiveness, how do recent agro-economic assessments suggest that specific adaptations may improve economic welfare and reduce vulnerability? What is economically efficient adaptation in the short and long-run? What are the limits to the agricultural sector’s adaptive capacity? This is certainly not the first review of climate impact assessments to California agriculture. Smith and Mendelsohn highlighted the importance of regional climatic impacts to several economic sectors in California , integrating across range of modeling approaches . The agricultural impacts are calculated by the Statewide Agricultural Production model under wet and dry scenarios. The results echo those of more recent SWAP studies, suggesting that field crop usage will decline by the end of the century under a dry scenario, though the decline in revenues will be partially offset by increased production of high-value crops. Prior to Smith and Mendelsohn , several notable studies examined the state of the knowledge of climate assessments at the US level . In particular, Lewandrowski and Schimmelpfennig integrate the knowledge from both programming and econometric studies of the agricultural sector. Other reviews have focused on the technical details of the different modeling approaches without discussing the results of the various studies . Following the pioneering work of Smith and Mendelsohn , this paper also focuses on California. The state is a leader in agricultural production, with $53.5 billion in sector cash receipts in 2014. California accounts for roughly 2/3 of US fruit/nut production, and 1/3 of US vegetable production . Roughly 1/3 of California cropland, or 9 million acres, is irrigated , making the state’s agricultural sector highly vulnerable to changes in groundwater and surface water supply . Several programming and econometric studies have been published after Smith and Mendelsohn , that operationalize the concept of adaptation . This paper begins with a review of regional impacts of climate change to California agriculture. It is followed by a review of the results from recent programming and econometric studies. The final section synthesizes the results from these studies, addressing lessons learned about vulnerability,adaptation, and adaptive capacity; and how these relate to economic welfare and Efficiency.Observational studies indicate that average daily temperature and daily minimum temperatures, particularly during the winter season, have increased in California . Average daily temperature in the US Southwest for the previous decade has been higher than any decade observed in the previous century . Barnett et al. find that daily minimum temperatures in winter have increased between 0.28– 0.43 C per decade from 1950–1999. Not just magnitude, but an increased rate of warming has been observed. Karl et al. suggest that the US Southwest has experienced the most rapid rate of warming in the nation. Observed precipitation patterns are fundamentally more complex and variable than temperature, exhibiting a high degree of variability across space and time. Trenberth et al. indicate that annual precipitation has decreased in the southwestern United States for the period 1901–2005.

Misunderstanding the issue as unidirectional, as opposed to cyclical and interconnected, results in inappropriate proposals. It is important to comprehensively evaluate the phenomena that initiate hunger, for GM and improved food production to be soundly argued. Any theoretical benefits of increased production are limited by the institutional issues that anchor the problem. The following will provide examples of past agricultural programs similar to those of AGRA and Monsanto for comparative assessment and make predictions about the potential of new initiatives. Specifically, the paper will compare examples from the first Green Revolution- which instituted high-input agriculture and high-yielding seed varieties in rural communities of the Global South from the 1940s through 1980s- and measure its outcomes against contemporary case studies from Malawi and Tanzania, where many programs have been recently launched. Southern African Development Community member states have been heavily impacted by recent production-driven initiatives that include the use of altered seed species. This group of nations has also been home to staunch opposition movements, and think tanks and institutes dedicated to finding alternative solutions to food and agriculture issues in the region. Critical evaluations of shifting food and agriculture approaches are particularly important in Malawi, Mozambique, Madagascar, and Tanzania,hydroponic nft system as these nations possess the first, second, third, and fourth highest agricultural GDP percentages in the regional economic community.

For clarity, the definitions of terms as used in this paper follow. Food security will be defined as “physical and economic access by all people at all times to sufficient, safe and nutritious food to maintain a healthy and active life;” a “food-secure state is one that can produce, purchase, or obtain as aid the food necessary to satisfy the needs of its population” . Food insecurity will be defined as an “inadequate physical, social, or economic access to food . Food sovereignty goes further than food security, the definition of which is unconcerned about where food comes from. Food sovereignty is specific in that it requires that peasants have access to agricultural lands and control over the food systems that produce that which they consume . Food self-sufficiency refers to the capacity of a nation to strictly meet all caloric needs with domestically-produced food. Again, food security contrasts with food sovereignty and food self-sufficiency, as it refers only to the ability of nations to obtain the required calories and nutrients to adequately feed its population, regardless of whether the food is produced domestically or whether smallholder farmers have control over distribution or the means of agricultural production. Trade agreements and international market values are particularly significant concerns in matters of food security, for if a nation does not produce sufficient yields or employ effective distribution policies for food produced within its borders, the food security of such a nation and its citizens lies precariously in its capacity to purchase and import the volume required to stave off hunger. This paper will examine the utility of increased production and surpluses of staple crops in food security efforts in East and Southern Africa, with emphasis on Malawi and Tanzania, and present findings and alternatives.

Past programs such as those instituted under the first Green Revolution, linked smallholders to corporations through agrodealers and retailers who facilitated the participation, sale, and distribution of seed and inputs to rural farmers. To better assess the potential of the production-driven approach employed by Bill Gates’ Alliance for a Green Revolution in Africa, Mosley, Schnurr, and Kerr thoughtfully reflect on this history. This comparison is most appropriate, for the two initiatives not only share a similar name. AGRA, like the program before it, focuses on raising yields by utilizing hybrid seed and increased use of fertilizers and pesticides. The following will employ a similar comparative approach, weighing past case studies against recent initiatives in East and Southern Africa in order to make educated predictions and recommendations regarding the potential of production-driven approach to resolve malnutrition. Past approaches stemmed from the belief that stalled agricultural production could be attributed to failure to ‘modernize’ or adopt high-input agriculture and industrial methods. The initial Green Revolution, most prominently launched in Mexico and South Asia, responded to this belief by converting rural smallholders to non-indigenous seed varieties. Reaping the full benefit of these varieties required costly upfront investments, not only in the purchase of high-yielding seed, but in the fertilizer inputs, chemical pesticides, and irrigation networks required of such seed. Detailed analyses, such as Tony Beck’s assessment of a farming community in West Bengal state, reflect the first Green Revolution’s impact on poverty in rural Indian communities and represent a break in the tradition of evaluating GR projects solely through the lens of its resulting outputs.

Specifically, Beck’s study examines socioeconomic change in the village of Fonogram from 1985-1992 and evaluates ways in which GR high-yielding boro rice varietals and irrigation facilities shifted the community over this period. Longitudinal data demonstrates that the GR was “mediated by already existing power structures and… flowed in a disproportionate fashion to the richer villagers” . A substantial 83% of the income generated from high-yielding rice in Fonogram was earned by farmers who were previously well off , as this group was able to purchase mechanical hand tractors and extensive irrigation systems and reinvest increased crop earnings into additional business opportunities in nearby towns. As a result, the highest income farmers’ profits compounded exponentially, and they grew to earn 9 times as much as the poorest households in the same village under the Green Revolution . The study demonstrates that GR practices, which involve capital payments, benefit inhabitants that already enjoy relative power and access to capital. The GR reinforced class, ethnic, and gender inequity. Preexisting patriarchal biases, in particular, were reflected in data showing that poor women benefitted least from the Green Revolution in Fonogram. Benefits did not ‘trickle down’ to poorer smallholders or women. From this case study, it can be noted that future initiatives that do not consider provisions for poor populations and women- those most vulnerable to hunger and malnutrition will invariably fail to provide them food security. Another assessment, incorporating four decades of data sets, also finds that inequity worsened in areas impacted by the first Green Revolution in rural Pakistan . GRhigh-yielding wheat debuted in the 1960s in response to critical famine in the region. Years later,nft channel despite recovering from food deficits at the national level , poverty increased in rural areas. That is, while the GR can be perceived as a success as it relates to improving national output, it further augmented inequity and wealth gaps. As Pakistan was experiencing four decades of increased national growth, there was a simultaneous decrease in land tenure security and rural employment, with many smallholders, “realiz that they could not keep pace with the high cost requirements of intensive farming,” reluctantly abandoning lands of cultural significance . Tenant-operated holdings declined at the same rate owner-operated farms grew and, by 2004, half of the rural population no longer possessed land. The structure of the first Green Revolution held intrinsic biases toward rich and commercial farmers, pricing hunger-vulnerable peasants out of participation instead of facilitating conditions under which they could better meet their daily caloric needs. With this, it failed to attend to the very problem which had served as the impetus for intervention in the 1960s. The Green Revolution in Mexico has been reduced to a plutocratic land reform initiative by some critiques, rather than as a mission to alleviate poverty and hunger following food shortages similar to those of Pakistan.

A survey of GR interventions from the 1940s-1980s demonstrates that these programs, funded by USAID, Alliance for Progress, and the Rockefeller Foundation , encouraged increased production specifically for export purposes. These neoliberal agriculture initiatives resulted in ongoing food crises, a consequence of increased vulnerability and heightened dependence on imports. The GR in Mexico, as in the examples above, altered the lives of peasant farmers residing on small communal landholdings. Here again, land would eventually come under the control of the wealthy, sometimes with the aid of dubious legal battles over land titles in courts that did not privilege traditional homesteads or the ancestral land claims of poor and indigenous people, facilitating further displacement . Dispossessed peasant farmers either found meager employment on expanding estate farms, relocated to competitive urban centers, or migrated abroad to apply their agricultural knowledge in places such as the United States, where they were vulnerable to exploitative labor practices. The Green Revolution of the 20th century demonstrates that considerations for existing power dynamics must be fully integrated into the planning and implementation of future such programs. This is especially true in SADC nations, where 70% of the population relies on smallholders for income, employment, and sustenance . Without such considerations, the rural poor may simply become further oppressed, displaced, and bound by poverty, conditions which are antithetical to hunger alleviation. Proponents of the approaches employed by the first Green Revolution cite statistics that show tremendous growth in production. However, as is perhaps most evident in the Pakistan example, the Green Revolution increased global food production, while global hunger increased in much of the Global South . Indeed, after the introduction of modified Mexican dwarf wheat species, chemical fertilizers and pesticides, and irrigation systems, production of wheat doubled in Pakistan and increased 40% in India within five years . These types of figures are often used to illustrate the validity of high input programs and modified seed usage in efforts towards hunger alleviation, despite the increases revealing nothing about decreased local poverty, increased nutrient and caloric intake, or the long-term sustainability and utility of initiatives. An assumption is made that these numbers equate to reduced hunger. But arguments displaying a strong relationship between export-driven productivity and hunger eradication in rural regions most impacted by GR are elusive. Rather, reports that favorably portray the 20th century Green Revolution list broad market value indicators and increased national export potential. These reports also tend to sometimes ambiguously refer to ‘farmers’ as beneficiaries of these programs without clarifying whether ‘beneficiary’ translates to being lifted out of poverty or explicating whether the farmers referenced were the original inhabitants of the land. Unfortunately, considerations for existing networks of power and relative vulnerability are not integrated into AGRA’s new programs on the continent. Therefore, predictably, just as with the former Green Revolution, data of 200 households in southern Malawi demonstrate that high-input maize production failed to provide food security or adequate nutrition. In fact, the poorest families were found to be those selling more maize . Upfront costs, loans, and unpredictable commodity prices neutralize profit potential. Agriculture companies and corporate-government partnerships that urge adoption of proprietary hybrid or genetically modified seed continue to conflate production with hunger alleviation, and donors and stakeholders continue to mistake increased national output with income opportunities that filter down to smallholders. Despite enthusiastic Monsanto and AGRA campaign messaging, which either imply or flatly profess that altered high-yielding crops can remedy deficiencies in local diets, varieties grown under these schemes have been overwhelmingly geared toward export, not domestic consumption. As neither the beneficiaries of food grown for immediate consumption nor the proceeds from export sales, populations of African farmers continue to experience economic hardship. The African Centre for Biodiversity has been closely monitoring the progress of AGRA initiatives on the continent in recent years, including extensive assessments in the SADC nations of Malawi and Tanzania . The following engages 2 programs documented by ACB: a program integrating a hybrid pigeon pea variety in the Kasungu and Lilongwe districts in Malawi, and an evaluation of AGRA agrodealer networks in Tanzania. It is important to note that the Malawian farmers were more readily able to participate in the pigeon pea program due to partial government subsidies. That the program ultimately failed meant not only lost incomes for smallholders with surpluses they could not unload, but federal losses in three years of proprietary pea and input purchases that could not be recouped. Selling surpluses is difficult, as “African farmers have to compete directly with the heavily subsidized and marketed agricultural products from the West” . US and European Economic Community subsidies enable overproduction and Western agribusinesses dump “agricultural commodities on Third World economies at prices often below the cost of production” .

Evaluation of both upregulated and downregulated genes among the experimental groups were in the direction of inflammation resolution. For example, in the Fat-1 genotype the observed differences in the downregulated genes were associated with cytokine production in macrophages, regulation of tight junctions and ECM disassembly, suggesting a move towards resolution of inflammation in tissue . Cytokine production and tight junctions contribute significantly to the maintenance of epithelial cell integrity and mucosal immunity of the lung in response to environmental insults as well as pathogens . Similarly, changes in ECM are important for recruitment of immune cells into and within the lung . Altogether, changes in these processes promoted by elevated levels of ω-3 fatty acids as in Fat-1 transgenic mice might affect how the lung responds to DE exposure. Particularly with TPPU, we identified down regulation of genes involved in IL-33 mediated signaling, as well as IL-5, IL-13, and IL-6 secretion. Overall, these data identified differences in immune clearance between the two genotypes and TPPU appeared to contribute to T-cell differentiation and regulation of PMN activation in part by downregulating the IL-33-mediated signaling pathway. IL-33 has previously been reported as an important regulator of Th- 2 immune response in allergic inflammation . The studies described herein do have numerous limitations. As with all transgenic animal models, the use of the Fat-1 mice to increase total body tissue levels of ω-3 PUFA and achieve an ideal ∼1:1 ratio of ω-6:ω-3 PUFA does not fully recapitulate the human condition. For example, differences in PUFA intakes are seen not only between individuals,nft hydroponic but temporal fluctuations in diet tendencies for each individual also undoubtedly alter daily to monthly PUFA levels, and the impacts of this will vary across different tissues based on PUFA uptake kinetics .

As PUFA substrate utilized during inflammatory events likely comes from both tissue sources as well as circulating blood and associated inflammatory cell infiltration, the impacts of recent dietary intake versus long-term dietary patterns on PUFA substrate availability are difficult to ascertain. Also, there are numerous recognized health benefits of diets high in ω-3 PUFA, due at least partly to their role in the endogenous production of SPM that regulate inflammation resolution and repair activities . SPM are produced temporally during an inflammatory response; their levels increase within hours to days following an inflammatory insult, and their production is critical to inflammation catabasis, including promoting neutrophil clearance, reducing inflammatory cytokine production, activating M2-like pro-resolution macrophages, promoting regulatory T cell recruitment, and activating tissue repair . Deficiencies in SPM generation pathways have been identified in asthma, and SPM are decreased in lavage, sputum, and/or exhaled breath condensates of COPD and asthma patients compared to individuals without lung disease . Therefore, an in-depth analysis of both ω -3 and ω -6 PUFA derived SPMs is necessary, and lipid metabolomics analyses of our data are currently underway in our laboratory. Another limitation is that we have used a model of organic dust exposure that utilizes a sterile-filtered aqueous extract of environmental dusts that is intranasally instilled to mice in a saline solution. This model will not fully recapitulate the inhalantinjury that is experienced by an individual working in a swine confinement facility, as it does not consider certain components, including live pathogens or gaseous components that have recognized respiratory impacts in these workers . It has been reported that airway inflammation in swine confinement workers differ from naïve subjects even after repetitive exposures, one displaying neutrophilic airway inflammation and the other neutrophilic and eosinophilic inflammation, respectively .

We have characterized a number of components that are likely to be involved in neutrophilic inflammation. Proteases are one of the components of agricultural dust that has been shown to be in part responsible for this type of inflammation . Our results are consistent with neutrophilic inflammation observed in people. In addition, since we delivered agricultural dust extract under light isoflurane anesthesia, the previously reported sex-related differences of isoflurane might confound some of the sex-related effects we observed in our study; however, given all the mice in each group underwent this light anesthesia the significant differences between the groups would still stand. Compelling data indicate the importance of having a balanced ω-6:ω-3 PUFA ratio for optimal health , yet the typical Western diet has a ratio of ∼10–20:1 . This imbalance is considered a driving or compounding factor in chronic inflammatory diseases, with many pro-inflammatory lipids formed from the ω-6 PUFA arachidonic acid, such as leukotrienes, thromboxanes and prostaglandins . It was recently reported that Veterans with COPD and an occupational history that include agricultural work had an ω-6:ω-3 PUFA ratio of ∼50:1 , underscoring the potential vulnerability of this population. Supplementation with ω-3 PUFA has demonstrated health benefits in clinical studies of cystic fibrosis, COPD, and other lung diseases . Thus, increasing ω-3 FA intake, possibly in combination with a reduced intake of ω-6 PUFA, could be an accessible and effective means of preventing and ameliorating airway disease in patients with inflammatory lung diseases such as those caused by agricultural dust exposures. Taken together, our investigations utilizing the Fat-1 mouse model in conjunction with sEH inhibition highlight the potentials of targeting repair/ resolution pathways therapeutically to promote lung protection from environmental dust exposures, and also highlight differences based on sex in the protectiveness offered by these interventions.

In the case of agriculture workers who are chronically inhaling inflammatory dusts, these outcomes hold promise for improving lung health outcomes via both limiting lung inflammation but also promoting repair following injury in this vulnerable population.The current projection for the world population to reach 9 billion by 2050 strikes an alarm when considering global food security. This drives a need, even greater than already present, to ensure sustainable and resilient agricultural systems with maximal crop production. For decades, countless studies have exemplified the benefits of using plant growth promoting rhizobacteria as soil inocula to improve agronomic productivity . Various strains of PGPR are able to fix nitrogen, solubilize phosphorus, sequester iron, suppress stress ethylene production by roots, produce plant growth hormones, antibiotics and anti-fungal compounds, and to enhance competitive exclusion of plant pathogens. The first recorded commercialization of PGPR was the use of rhizobia in 1895 . Since then, over a dozen different genera have been introduced to soils or seeds and many are sold commercially . In fact, Popular Science named Bio-Soil™, a cocktail of over 300 species of PGPR developed at Michigan State University, as one of the top 10 solutions for the future of farming . PGPR can be categorized based on their beneficial traits. For example; a nitrogen fixer would be termed a biofertilizer,nft system an organism emitting plant growth hormones is a phytostimulator, and ones secreting antibiotics and antifungal compounds are bio-control agents. While PGPR offer a multitude of benefits for healthy plant growth and development, this body of work focuses on mineral phosphate solubilizing bacteria and phytostimulators. Root colonization by phytostimulators has been shown to enhance root development, resulting in greater total root surface area and enhanced nutrient and water absorption. In turn, phytostimulators play the greatest role in increasing crop yields in stressed agriculture, as plant-hormone interference can induce plant systemic tolerance to drought, flooding, salinity, and heavy metals . Phosphorus is a macronutrient essential for plant growth and development and current agricultural practices have become reliant on the application of P fertilizers, especially phosphate rock. Consequently, current reservoirs of phosphate rock are expected to become depleted in 50– 100 years . Inorganic P accounts for approximately 35– 70% of total soil P . Plants are able to uptake Pi in its soluble forms . In soils with neutral to slightly acidic pH’s an abundant amount of Pi is available in these soluble compounds, but unfortunately this can result in the loss of P from plant root zones via leaching. Also, Pi forms highly insoluble mineral complexes with Ca in alkaline soils and with Al and Fe in strongly acidic soils, such that it has maximum availability to plants only at near neutral pH . These issues present a challenge as approximately 75% of P added to soil via fertilizers becomes non-plant available Rodr g e and raga, 1999. To release mineral-bound Pi some bacteria have MPS capabilities, typically achieved by the release of organic anions and correspondingly free protons . This lowers the pH of the soil solution and can release P from Ca, Al, and Fe complexes Rodr g e and raga, 1999). Hence, MPS bacteria can function as biological fertilizers, releasing mineral-bound Pi currently present in soils and reducing the need for additional P fertilization. Plant growth promoting microorganisms can affect root development by generating growth hormones or depleting hormones that would otherwise cause stunted root development.

Ethylene, a gaseous phytohormone, is critical for many plant developmental stages. While an initial peak in ethylene concentration in plant tissues is essential for root and stem growth and flower and fruit development, its continued accumulation triggers a cascade of responses including inhibition of root elongation, induction of hypertrophies, acceleration of aging, promotion of senescence and abscission, and inhibition of auxin transport . Ethylene can also inhibit stimulation of cell proliferation and elongation by repressing auxin response factor synthesis . The ethylene-mediated stress response can be activated by many environmental factors such as heavy metal contamination, high salinity, flooding, drought, and phytopathogens. The pathway to ethylene biosynthesis in plants involves the conversion of methionine into S-adenosyl-L-methionine by an enzyme SAM synthetase followed by the hydrolysis of SAM to form 1-aminocyclopropane-1-carboxylic acid by ACC synthase. In the next step, plant produced ACC oxidases bind to ACC with high affinity, with Km values range from about 50– 120 µM, and catalyze the conversion of ACC to ethylene, carbon dioxide and hydrogen cyanide . Conversely, if ACC is exuded from root tissues, root colonizing bacteria can uptake the ACC and use it as a nitrogen source for growth. Microorganisms with ACC deaminase cleave the propane ring of ACC to produce ammonia and α-ketobutyrate, both of which are then metabolized by bacteria . However, ACC deaminase enzymes have low binding affinities for ACC, with Km values ranging from 1.5– 17.5 mM . Thus, it has been suggested that ACC deaminase must be available at 100– 1000 fold greater amounts than ACC oxidase to reduce the accumulation of deleterious ethylene levels in plant tissues . The genetic regulation of the ACC deaminase structural gene, acdS, has been well described for Pseudomonas putida UW4, detailing an intricate regulation promoted by an ACC-bound complex and inhibited by a protein transcribed upstream of acdS, termed the ACC deaminase regulatory protein, AcdR. The intergenic space between these genes has been identified as the P. putida UW4 promoter region for AcdS, where binding of both regulatory complexes occurs . In particular, bacterial strains that generate an auxin compound, indole-3-acetic acid , stimulate total root length, root hair formation, and root branching when colonizing plant rhizospheres . When applied as a seed coat, Enterobacter cloacae UW5 promoted increased root branching and total root length in both mung bean and canola in growth pouch assays . This activity was explicitly linked to IAA production by UW5 . The indole-3-pyruvate pathway is considered to be the major pathway for IAA synthesis in plants and is also utilized by many bacteria . The genetic regulation of a key enzyme, indole-3-pyruvate decarboxylase , involved in this pathway has been well described. Strain UW5 has been shown to have a pathway to IAA production in which the genetic regulation of ipdC is induced by tryptophan . The promoter region of the IpdC gene has a tyrosine transcriptional repressor recognition box . The transcription of ipdC is promoted by the binding of the TyrR box by tryptophan, phenylalanine, and tyrosine, all of which are plant root exudates . The development of commercial bio-fertilizers is difficult as a result of poor or inconsistent survival rates of soil inocula, making quality assessment and verification of any given product very difficult . For example, Acea et al.effectively demonstrated that declines in population densities of soil inocula, such as Pseudomonas, Rhizobium, and Bacillus spps. corresponded to increases in populations of bacterial predators and bacterial competitors . Additionally, direct incorporation of liquid inoculum into soils is complicated by bacterial adhesion to soil particles, which greatly reduces their vertical transport and the ability to colonize roots located in the subsurface soil profile .

Photodynamic therapy has emerged as an efficacious adjuvant treatment modality for several types of cancer.In PDT, light is used to locally excite a photosensitizer to generate reactive oxygen species. The resulting oxidative stress disrupts organelle functions, promotes cell apoptosis, and damages the tumor vasculature that supply oxygen and nutrients required for the tumor to survive.While a few PDT therapies have received FDA approval , efficient delivery of the PS to the target site remains challenging. Tumor accumulation of the PS is generally poor due to the physicochemical properties of the PS.Therefore, large doses are administered to compensate for the poor drug accumulation at the target site. This is particularly unfavorable because most PS suffer from slow in vivo clearance, which increases toxicity. For example, as skin is highly vascularized and easily exposed to light, the long circulation time of PS promotes skin phototoxicity. As a result, patients are required to limit their exposure to the sun several weeks post-treatment. Therefore, there is a critical need to develop delivery systems with enhanced clearance that promote the accumulation of the PS in the tumor site. To this end, I turned toward the development of plant virus-based nanoparticles for the delivery of PS. VNPs have been developed as carriers for the delivery of contrast agents, chemotherapeutics, protein therapies, epitopes, agro-pesticides, as well as PS . Plant VNPs have several attributes that are favorable for nanomedicine delivery and in particular PS delivery. Bio-manufacturing is well established and the biologic platform offers well-defined,hydroponic channel monodisperse structures that can be tailored with molecular precision.

Plant VNPs are non-infectious toward mammals, and most importantly the proteinaceous nanoparticles are cleared rapidly from circulation and from tissue,thus making this a particularly attractive platform for PS delivery. Plant VNPs as well as bacteriophage-derived nanoparticles have been developed for PS delivery;in most instances PS agents are covalently coupled to viral carriers. However, covalent binding of the PS to nanoparticles may impair their photoactivity due to quenching and reduced molecular freedom, and in turn limit their intracellular activity. Therefore, non-covalent drug delivery may be advantageous to enhance and control steady release of the PS within the tumor environment. This strategy relies on hydrophobic-hydrophilic and electron charge interactions between the PS and its carrier. In this work, I utilized two high aspect ratio, soft matter tubular nanostructures for PS delivery, namely tobacco mosaic virus and tobacco mild green mosaic virus . TMV and TMGMV were selected as carrier platforms based on their well-established surface chemistry and elongated shape. Elongated nanoparticles have enhanced blood margination, transport across tissue membrane, cell adherence, and macrophage avoidance, promoting their accumulation in the tumor tissue.TMV and TMGMV self assemble helically around a single-stranded RNA genome to form a 300 x 18 nm rod with a 4 nm wide hollow interior channel . As described in chapter II, both particles are made of 2,130 identical copies of coat protein units; TMV and TMGMV share 86% sequence homology.Of particular interest, the interior channels of TMV and TMGMV are covered with solvent exposed glutamic acids that are readily available for electrostatic loading of positively charged guest molecules .While TMV has been extensively studied for clinical applications, including the delivery of PS,this is the first study investigating TMGMV for medical applications. To probe drug loading and release, I studied the monocationic, dicationic, tricationic and tetracationic version of a zinc porphyrin photosensitizer. Lastly, we selected one formulation and developed a cancer cell targeting strategy to further enhance treatment efficacy.The TMV results can be attributed to the combined effect of electrostatic and hydrophobic/hydrophilic interactions; the greater the positive charge the better stabilization inside the TMV interior channel.

In addition, the increased hydrophobic nature of the monocationic and dicationic Zn-Por formulations in combination with their electrostatic properties led to the formation of more aggregates compared to their tricationic and tetracationic counterparts, thereby reducing the loading efficiency. Several factors may explain the differential loading results between TMGMV and TMV. In chapter II, I have previously compared the amino acids sequences of TMV and TMGMV and analyzed their distribution of charged residues on both the inner and outer surfaces of the virus.While it has been shown that only two glutamic acid residues are chemically available on TMV , our analysis revealed that in addition to the Glu 95 and Glu 106 in the interior channel of TMGMV, Glu 145 and aspartic acid 66 were also exposed on the outer surface and could be available for electrostatic charge interactions. The difference in the amino acid sequences of TMV and TMGMV could also play a role in the difference in loading by changing the charge and hydrophobicity surrounding the glutamic acid residues. Furthermore, the virus coat proteins are not rigid structures, and therefore small molecules could diffuse in between coat proteins.Based on the above studies, I prepared drug-loaded VNPs using the 2000:1 Zn-Por:VNP ratio. I studied whether changing the pH of the 10 mM KP buffer solution would influence the loading efficiency of Zn-Por into TMV and TMGMV . At pH 3, VNPs aggregated and disassembled, which led to lower yields. The corresponding loading efficiency was low due to the protonation of carboxylate groups, resulting in weak electrostatic interaction. At pH 5, the reaction yields and loading efficiency were improved compared to pH 3, and reached their maximum at pH 7.8. Increasing the pH to 10 did not increase the loading yield, but rather just slightly decreased loading efficiency and reaction yields. While ~60−75% of starting materials were recovered at pH 7.8, the yield dropped to ~40% at pH 10.

Based on the findings of the pH studies, I conducted the remaining experiments at pH 7.8 due to the relatively high loading efficiency and recovery observed at this pH. Next, I analyzed the drug release profile of each Zn-Por:VNP formulation . 1 mg of particles was resuspended in 300 μL PBS and loaded in triplicate in 10,000 MW cutoff Slide-A-Lyzer MINI dialysis units for 72 hrs. To mimic physiological conditions, samples were dialyzed against 3 L of PBS adjusted to pH 7.4 as well as pH 5 at 37°C. At time t = 0, 1, 3, 6, 18, 24, 48, and 72 h, 10 μL was extracted from each dialysis unit and the remaining Zn-Por entrapment was measured by UV/Visible spectroscopy. The half-life t1/2, defined as the time required for 50% of the drug to be released from the VNPs, decreases as the electropositivity of Zn-Por increases. At pH 7.4, TMV: Zn-Por4+ and TMGMV: Zn-Por4+ formulations had the lowest t1/2 . In contrast, only 20% and 25% of ZnPor1+ was released from TMV and TMGMV respectively within 72 hrs. The release profiles of Zn-Por3+ were similar to that of Zn-Por 4+, while the release rates of Zn-Por2+ were in between those of Zn-Por4+/3+ and Zn-Por1+. While the t1/2 values of each Zn-Por:VNP formulation were slightly lower at pH 5, the trend remained the same. These results indicate that the dominant force of interaction between TMV/TMGMV and Zn-Por is not electrostatic,hydroponic dutch buckets but rather hydrophobic/hydrophilic interactions. Since Zn-Por becomes more hydrophobic as its electropositivity is reduced, its ability to solubilize in PBS surrounding the VNP is impaired, thereby decreasing the rate of drug release. I also tested stability of the Zn-Por:VNP formulations under storage conditions , and observed a slow and constant release of Zn-Por from TMV and TMGMV over a period of 6 weeks Less than 45% of Zn-Por was released from the other formulation within 6 weeks. To evaluate in vitro efficacy of Zn-Por:VNP formulations, I first compared TMV and TMGMV’s uptake by B16F10 melanoma cells. Melanoma was chosen as a model because PDT has shown promise in melanoma.While most melanomas are removed by surgery supplemented with adjuvant chemotherapy and/or immunotherapy, some melanomas remain unresponsive to these therapies. A growing body of data indicates that PDT could be applied as an adjuvant therapy for those melanomas not responsive to traditional therapies.For cell uptake studies, TMV and TMGMV were conjugated with the fluorophore Cyanine 5 using solvent exposed tyrosine side chains click chemistry,followed by the purification of the reaction mixture as previously described. The covalent attachment of Cy5 was confirmed by UV-vis and denaturing SDSNuPAGE gel electrophoresis . We have previously demonstrated that a minimum conjugation of Cy5 to ∼8% of TMV coat proteins is sufficient to yield maximum fluorescence intensity.237 TMV and TMGMV particles displayed ~160 and ~490 dyes respectively. The higher dye conjugation efficiency in TMGMV could be due to differences in the chemical micro-environment and greater surface exposure of the tyrosine side chain.

The corresponding average distances between fluorophores are equal to 2.7 nm and 1.6 nm for TMV and TMGMV respectively, which are large enough to prevent quenching due to energy transfer between dye molecules and trapping by dimers.Therefore these Cy5-TMV and Cy5-TMGMV constructs are suitable for imaging experiments. To assess VNP–cell interactions, B16F10 melanoma cells were incubated with 100,000 VNPs per cell at 37 °C and 5% CO2 for 1 h and 8 h in Dulbecco’s modified Eagle’s media supplemented with 10% fetal bovine serum and 1% penicillin-streptomycin. Cells were washed thoroughly with FACS buffer 0.5 M EDTA, 1% FBS and 2.5% 1 M HEPES pH 7.0 in DPBS and fixed with 2% paraformaldehyde. Cells were then analyzed using a BD Accuri C6 Plus flow cytometer and 1 x 104 events were recorded. Data were analyzed using FlowJo v8.6.3 software. After 1 h of incubation, 85% and 100% of TMV and TMGMV were taken up by B16F10 cells, respectively . This is reflected by an increase in mean fluorescence intensity compared to cells only . The slightly higher uptake of TMGMV may be attributed to greater particle instability during viral production and purification, which causes some of the particles to be broken218; a shorter TMGMV rod would have a faster rate of cell penetration. Nonetheless, the cellular uptake of TMV and TMGMV reached 93% and 100%, respectively, after 8 h of incubation. This time point was selected to allow VNPs to traffic through the cells before proceeding with the photodynamic treatment. I evaluated efficacy of the drug delivery approach against B16F10 cells using previously established white light therapy.The following samples were tested: Drug-free VNPs, free Zn-Por, and Zn-Por-loaded VNPs, and a dark control for each sample was included. Cells were incubated with 0.001, 0.01, 0.1, 1, 5, and 10 μM of Zn-Por, Zn-Por:VNP, or controls for 8 h at 37 °C and 5% CO2. Cells were washed to remove any Zn-Por that was not endocytosed and samples were illuminated under white light for 30 min . Control samples were kept in the dark at 37 °C and 5% CO2. In all experiments, neither dark controls nor any of the VNP only controls showed significant cell toxicity. Free Zn-Por1+ was 1.8 to 2.8-fold more effective compared its TMV/TMGMV formulation; this reduced efficacy was even more dramatic for the Zn-Por3+ loaded particles which showed a 30-50 fold decrease in efficacy. The decreased drug activity of VNPs loaded with Zn-Por vs. free Zn-Por is expected. The reactive oxygen species produced by PS drugs have a very short half-life and act locally from their generation site. Therefore, the subcellular localization of the PS greatly influences its phototoxicity. Like most nanoparticles, TMV and TMGMV are internalized by endocytosis and follow the endosomal-lysosomal pathway. Previous data suggest the phototoxicity of PS localized in lysosomes is significantly reduced compared to PS localized in other organelles, in particular in mitochondria.On the other hand, hydrophobic PS with cationic charges such as free Zn-Por is likely to localize in mitochondria.Nonetheless, TMV and TMGMV are here used to improve the bio-availability and tumor accumulation of Zn-Por while reducing non-specific tissue toxicity. TMV and TMGMV can be further chemically or genetically modified to display moieties such as cancer cell targeting ligands, cell penetrating ligands, and chemotherapeutics for combined therapy, which would further improve the treatment efficacy. As a proof of concept, we set out to develop a targeted Zn-Por delivery system. We chose Zn-Por3+ and TMV, in particular we used the well-established and characterized Lys-added mutant denoted as TMVlys. While TMGMV showed greater toxicity than TMGMV, the genetic engineering of TMGMVlys mutant has yet to be established in the future. TMVlys offers amine functional groups for bio-conjugation: targeting ligands synthesized with a terminal Cys side chain can be conjugated using heterobifunctional NHS-maleimide linkers. Here we chose the F3 peptide as the ligand.

They demonstrated that abamectin encapsulated in RCNMV had increased stability and superior mobility in soil compared to free abamectin, which resulted in enhanced bio-availability and treatment efficacy in tomato seedlings. As expected, no viral infection in the tomato seedlings was observed, as tomato is not a RCNMV host species. In the present work, I propose the use of tobacco mild green mosaic virus , also known as the U2 strain of tobacco mosaic virus , as a carrier to deliver nematicides. TMGMV self-assembles into a 300 by 18 nm rod-shaped virus with a 4 nm wide hollow channel. The high aspect ratio soft-matter nanotube may provide a promising alternative over the spherical platform technologies, i.e. most synthetic nanoparticles as well as RCNMV. The nanomedicine field has demonstrated that carrier shape impacts the in vivo fates with elongated materials conferring advantages with enhanced margination, diffusion, and penetration through tissue.Whether high aspect ratio materials perform better in soil remains to be seen. Another advantage of the TMGMV platform is the high surface area , 3.9 times larger than RCNMV , which may allow for higher payload delivery. TMGMV is already EPA-approved: Solvinix, a formulation of TMGMV mass-produced by BioProdex, is commercially available as an herbicide in the state of Florida for the treatment of the invasive weed tropical soda apple.TMGMV is not transmitted by insects, pollen, or other vectors; it is not seed borne and cannot self-disseminate. While TMGMV is capable of infecting solanaceous plants , TMGMV is unable to penetrate and infect healthy plants in the absence of a lesion wound.

Furthermore, Solvinix was tested on 435 plants representing 311 species,blueberry box among which only 8% of plants were killed.It is therefore safe to conclude that TMGMV can be applied in the field with little to no risk to the environment or the crop itself. Although there are a few species of plants to which TMGMV is lethal,it is important to remember that the remaining 3000 species infected by parasitic nematodes are not susceptible to TMGMV. While its structure is known to atomic resolution ,the chemistry of TMGMV has not yet been established. Making use of the structural information and the well established chemistries for tobacco mosaic virus , I developed bio-conjugation techniques and non-covalent drug loading strategies for TMGMV. As a proof of concept, I used the anthelmintic drug Crystal Violet in our studies.The supernatant was subsequently analyzed by UV/visible spectroscopy .TMGMV is the U2 strain of tobacco mosaic virus ; the latter has been extensively studied in plant pathology and structural biology since the 1900s and more recently in nanomedicine, biotechnology and energy research.173 Therefore, the surface chemistry of TMV is well understood. Here I set out to establish the chemistry of TMGMV. The amino acid sequences of the coat proteins of TMV and TMGMV present 72% homology; also the structural overlay of a single CP of TMV and TMGMV reveals a high degree of structural similarity, only 14% of the amino acids do not overlap in the crystal structures . This is also reflected when comparing the assembled nucleoprotein complexes of TMV and TMGMV . Just like TMV, TMGMV forms a cylindrical structure measuring 300 by 18 nm with a 4 nm-wide hollow interior channel. The TMGMV particles consist of 2130 identical copies of CP units arranged helically around a single-stranded RNA genome .

Analysis of the structure reveals the amino acid profile on the exterior and interior surface: because LYS, CYS, TYR, ASP, and GLU are often targeted for bio-conjugation or electrostatic drug loading, I analyzed the TMGMV structure for presence of these residues. While solvent-exposed LYS and CYS side chains were not identified in TMGMV , several TYR, ASP and GLU residues were found to be solvent-exposed on the exterior/interior TMGMV surfaces. Structural data indicate TYR2 to be exposed on the exterior surface – this is different from the structure of TMV, for which both TYR2 and to a greater extent TYR139 are solvent-exposed on the exterior surface . The TYR2 side chain of TMGMV could provide a potential target for bio-conjugation, e.g. the introduction of a fluorescent label for imaging and tracking studies as described below. Further, I identified ASP66 and GLU95, 106, and 145 to be solvent exposed, with GLU145 and ASP66 located on the exterior surface and GLU95 and GLU106 on the interior surface . This is similar to the structure of TMV, for which GLU145, ASP64 and ASP66 are solvent-exposed on the exterior surface while GLU97 and GLU106 are solvent-exposed on the interior surface . However, it should be noted that previous research identified GLU97 and GLU106 to be the only carboxylates in TMV that are reactive toward carboxylate-specific chemistries; GLU145 and ASP64 and 66 were not found to be reactive.The presence of GLU/ASP residues in TMGMV would allow for functionalization through bio-conjugate chemistry or electrostatic loading of positively charged guest molecules, as we previously described in the case of TMV.Lastly, I analyzed the surface charge of TMGMV and determined that the inner and outer surfaces carry a net negative coulombic charge with the interior being more electronegative than the exterior . Together these data indicate solvent-exposed TYR side chains on the exterior surface of TMGMV and addressable carboxylates – possibly on the exterior and interior surfaces. With the structural information in hand, I set out to develop TMGMV as a carrier for nematicide delivery.

Specifically, I chose to work with crystal violet as a proof-of-concept, because this therapeutic compound is fluorescent and thus streamlines the analysis. The positively charged CV was loaded into TMGMV making use of electrostatic interactions and concepts that were previously developed to load positively charged platinum drug candidates and porphyrin derivatives into TMVThe reaction mix of 6000:1 CV:TMGMV resulted in the highest loading efficiency while still yielding dispersed TMGMV particles: 68% of the CPs were modified with a CV molecule. Assuming a full length TMGMV particle , each TMGMV would carry ~ 1500 drug molecules. This formulation was subsequently used for all following studies. When compared with TMV-drug formulations, the TMGMV formulation yielded comparable results: I previously reported the loading of 2,000 phenanthriplatin per TMV206 and 900 copies of a porphyrin derivative ZnPr per TMV.235 In those cases, the loading procedure was similar, in which a positively-charged guest molecule was loaded via electrostatic interaction with TMV’s interior carboxylates. As in the case of TMV, the interior channel of TMGMV is lined with a dense layer of carboxylates – this, in combination with the more electronegative interior surface,blueberry package may suggest that drug loading occurs on the inside channel. However further studies would be needed to rule out drug association with the exterior surface in both the cases of TMV and TMGMV. To compare the drug loading efficiency of the rod-shaped TMGMV system to the icosahedral RCNMV-based nematicide carrier, the number of drug molecules was normalized to the molecular weight of the nanocarrier yielding ~3.6 × 10-5 CV per dalton of TMGMV protein, while only ~1.8 × 10-5 abamectin molecules were loaded per dalton of RCNMVprotein. In other words, when normalized per molecular weight, twice as much drug molecule can be loaded per TMGMV than compared to RCNMV. The structural integrity of non-modified TMGMV and CVTMGMV were assessed by size exclusion chromatography and transmission electron microscopy . SEC measurements revealed no significant difference comparing native TMGMV and CVTMGMV; both particles showed the same elution profile . Further, TEM imaging of TMGMV and CVTMGMV revealed rod-shaped samples with no apparent differences when comparing TMGMV and CVTMGMV ; TEM imaging indicates that the average length of TMGMV and CVTMGMV is comparable measuring 146 ± 97 nm and 136 ± 76 nm, respectively .It is possible that this is an artifact from the TEM grid preparation, i.e. the particles may break during the drying process. However, it is important to note that there are no apparent differences comparing the TMGMV and CVTMGMV, indicating that the nucleoprotein complex withstands the loading and purification process. To gain insights into whether CV- loading into TMGMV is indeed via electrostatic interactions with GLU and/or ASP residues, chemically modified TMGMV in which the carboxylates were neutralized was prepared. To do so, EDC coupling was used to introduce alkyne ligands at the carboxylates, for subsequent addition of biotin labels using Cu-catalyzed alkyneazide cycloaddition . The protocols are detailed in the methods and were adapted from previous methods established for bioconjugation to TMV.Biotinylation was confirmed by western blot , yet quantitative data could not be obtained. To quantify the degree of labeling, the fluorescent Cy5 dye was conjugated to GLU/ASPTMGMV, yielding ~275 dyes per full length TMGMV, or about 13% of CPs were modified with Cy5 . Biotinylated and alkyne-labeled TMGMV were then used in CV-loading experiments, and I observed a 40% decrease in CV loading when using alkyne-labeled TMGMV compared to unmodified GLU/ASPTMGMV . Severe aggregation was observed when biotinylated TMGMV was used in CV loading experiments .

This phenomenon may be explained as follows: if the chemistry of TMGMV and TMV is matched, then biotins will be displayed along the interior channel, preventing the positively charged guest molecules to be loaded and protected inside the TMGMV channel – instead CV may cross link the particles through interactions with the while less negative, also negatively-charged exterior surface. Because the data indicate that CV-loading is mediated through the solvent-exposed GLU/ASP acids, and in light of the TMGMV structure and its similarities to the known biochemistry to TMV,I therefore expect that interior loading of CV is achieved by this method. Next, I evaluated the release profile of CV from the TMGMV nanocarrier. The release rate of CV from CVTMGMV is expected to be proportional to the pH of the bathing conditions as well as temperature. Based on thermodynamics, the rate of diffusion should increase with temperature. Furthermore, as pH decreases, a larger number of carboxylate groups become protonated and carry a net neutral charge that can no longer interact with the positively charge CV and consequently, free CV should diffuse away from TMGMV. Therefore the release rate of CV should be higher at lower pH and higher temperatures. To test this experimentally, 1 mg of a 1 mg.mL-1 solution of CVTMGMV was prepared as described above and dialyzed against various buffers for 72 h . I tested the release profile at room temperature and 4°C to evaluate two extreme upper soil thermal conditions.Sodium acetate and PBS buffer solutions were chosen to mimic the acidic and neutral soil environments respectively. Diffusion of CV from CVTMGMV was also evaluated in KP buffer, which was used during loading and storing conditions of the sample. Free CV, in a concentration matched to the concentration and number loaded into TMGMV, was also dialyzed in KP buffer at 4°C as a positive control. As expected, increased release rates of CV from CVTMGMV were observed at low pH and high temperature . Approximately half of the free CV was dialyzed within 1.6 h and complete release was observed in less than 18 hrs, while delayed release profiles were observed for the CVTMGMV nanoparticle formulations. For CVTMGMV, 50% of CV was released only after 5 h in acidic conditions at room temperature , with complete release achieved after about 24 hrs. These conditions most realistically mimic the soil environment. In stark contrast, release in storing conditions was significantly slower, with 50% of CV released within 13 hrs, and complete release was not observed within 72 h. This is promising for application of these nanoparticles, however it would be advised to prepare fresh formulations before application in the field. We have previously reported similar results with the release of the cancer drug phenanthriplatin from TMV;half of the encapsulated chemotherapeutic was released after 1 h at pH 5 and 24 h at pH 7.4. On the other hand, encapsulated porphyrin derivatives loaded in TMV were found to be stably encapsulated for at least one month when stored at 4°C and pH 7.I hypothesize that the increase in stability of the porphyrin drug was due to its higher electropositivity: the compound used carries 3 positive charges. In contrast, phenanthriplatin and CV carry 2 and 1 positive charges, respectively. Compared to the previously reported RCNMV carrier, the release rate of CV from TMGMV is slightly faster than that of abamectin from RCNMV in acidic soil conditions. 50% of abamectin was released within 8 and 7 h at pH 5.2 and 7.4 respectively .

When immobilization processes are considered retention is increased to an even greater extent and peak in-stream concentrations range from approximately 8.1×10−3 to 1.8×10−5 oocysts/mL at 100 m and 700 m, respectively. Thus, oocyst in-stream concentrations quickly decreased when immobilization processes were considered, which can then remain immobilized within the sediments and remobilize at a later time .In scenario 1, 99.7% of the oocyst inputs already passed 100m at 1 month with only 0.1% of the inputs inactivated, however when immobilization processes were considered only 33.8% were observed in the mobile phase prior to the stop of the input . Although in-stream concentrations decrease relatively quickly , pathogen accumulation within immobile zones results in high counts within these areas for long periods of time . After relatively quick immobilization, Cryptosporidium is slowly released back to the water column, where at 100m the Cryptosporidium immobilized decreases from 2.2×109 to 1.4×109 oocysts, 66.2% to 43.0% of the inputs, from 1 to 6 months . These results demonstrate that Cryptosporidium persists for months at 100m and may rework its way downstream, but will remain within the first 700m for years after the input under base flow conditions .When considering a pathogen with such a low infectious dose,grow bag gardening the retention within streambeds can dramatically increase the time during which thresholds for safe consumption are exceeded. These results demonstrate that both hyporheic exchange and immobilization processes within sediments and other slower moving areas increase pathogen persistence in streams.

Cryptosporidium oocysts are readily immobilized within the first 100 m and stay for days to years within transient storage areas. In fact, at 100 m Cryptosporidium in-stream levels do not reduce to below 10−5 oocysts/mL until 280 days after the start of a 1-month input. At 700 m from the simulated input of Cryptosporidium, in-stream concentrations only slightly exceeded 10−5 oocysts/mL for a short period of time, but the majority were immobilized in transient storage areas within the 700 m reach downstream of the source. Te numbers of viable oocysts remaining in the 100m reach downstream of the input decreased over time, while the numbers of viable oocysts from 100–300m increased and then decreased from 0 to 24 months and the reaches further downstream showed a consistent increase in the number of viable oocysts. The constant reworking of sediment beds has previously been observed, and is a combination of flushing, trapping, and accumulation of fne sediment and microbes that occurs both at base flow and during high flow events. The model scenario was for 1 month and only one stream inlet, but the landscape is continuously adding Cryptosporidium to the stream, which can result in even more accumulated pathogens within the stream. As non-point sources are distributed among the watershed, there will be constant and sporadic inputs simultaneously, but the majority of the input will be deposited within the first 100 m, at least initially before remobilization processes move the pathogenic microorganisms further downstream. Cryptosporidiosis remains an important waterborne disease in both the United States and Europe, posing significant public health and economic problems. Likely the high risk is due to a combination of a low consistent input of Cryptosporidium, long retention times, and low inactivation rates that can result in long-term accumulation within streams.

Accumulated pathogens can subsequently resuspend slowly back into the water column during base flow or as a pulse in response to a storm event. Previous cryptosporidiosis outbreaks have occurred following a high flow event, where microbes are rapidly resuspended due to scour of streambed sediments. The extent of microbial resuspension is dependent on the frequency of high flow events, microbial colonization of benthic bioflms, macrophytes, and sediments, and potential for erosion or remobilization from these reservoirs. Implications of pathogen persistence within stream storage areas, and in particular sediments, includes increased risk especially when climate change is expected to increase the duration of drought periods and lead to intensified rain events. This model framework can be used to help predict response to storm events as pathogens remobilized during high flow conditions are directly related to the in-stream source of pathogens accumulated during base flow. Furthermore, this model framework can incorporate new information to improve predictions of specific Cryptosporidium species. The use of molecular diagnostic tools has significantly improved our understanding of cryptosporidiosis epidemiology and now it is known that human cryptosporidiosis is predominantly caused by C. hominis and C. parvum. It has also recently been discovered that Cryptosporidium can multiply without host cell encapsulation , which potentially poses an even greater environmental risk. Overall net inactivation was observed in our study case, but specific sub groups and growth can be incorporated into the model framework as needed for specific cases or applied to other pathogenic bacteria of interest.

This could be especially useful if supporting lab-scale experiments have been conducted to parameterize the retention within the sediments, previously shown to control the late-time tailing of observed in-stream breakthrough curves. Here we presented how the mobile-immobile model framework is a first step for accurately characterizing pathogen transport and retention in stream. A mobile-immobile framework can accurately characterize pathogen dynamics in streams and incorporate key processes that lead to long residence times. The fate of the pathogens after entering a stream and the long-term retention has been underestimated if hyporheic exchange and immobilization processes within sediments and other storage areas is not considered. The multi-scale model enables information on pathogen retention in column experiments to be related to net downstream transport at the stream-reach scale. Therefore, while it is not possible to conduct field scale tracer experiments with pathogens, lab scale studies, such as column experiments can be used to parameterize reach-scale estimates,plastic grow bag as demonstrated within this modeling study. The combination of stream reach-scale analysis and multi-scale modeling improves assessment of Cryptosporidium transport and retention in streams to predict downstream exposure to human communities, wildlife, and livestock. The mobile-immobile model framework can be modified to any system of interest to estimate base flow pathogen accumulation and therefore help predict the potential loads of resuspended pathogens from the streambed to the water column in response to a storm event.Bio-solids are the nutrient-rich byproduct of wastewater treatment operations and large quantities are generated. For example, approximately 750,000 dry tons is produced annually in California and 54% of these bio-solids are applied on agricultural lands, 16% are composted and the remaining 30% goes to landfills . Concerns about potential health and environmental effects of land application of bio-solids include possible off-site transport of pathogens, heavy metals, and trace organic constituents such as TCS . A less explored set of potential impacts is how TCS and other bio-solid-borne contaminants affect ecosystem processes and associated soil microbial communities. Potential impacts on soil microorganisms are important to assess since these organisms mediate much of the nitrogen, carbon and phosphorous dynamics in soil, biodegrade contaminants, create soil structure, decompose organic compounds, and play a major role in soil organic matter formation . We hypothesized that bio-solids containing TCS would have detrimental effects on soil microbial communities by decreasing biomass and altering community composition in agricultural soil. Our objectives were to evaluate the effects of increasing amounts of TCS on soil microbial community composition in the presence and absence of bio-solids. We used phospholipid fatty acid analysis to characterize the response of microbial communities; the method provides information about microbial community composition, biomass, and diversity . Experiments in which TCS was added to soil without bio-solids allowed the relative effects of bio-solid and TCS addition on microbial community composition and function to be compared and also provided a “secondary control” because TCS-free municipal bio-solids are essentially unavailable in the United States .

Triclosan was purchased from Fluka . Yolo silt loam was collected from the Student Experimental Farm at the University of California, Davis at a depth of 0 to 15 cm. The soil was passed through a 2 mm sieve and stored at 4 °C until use. Bio-solids originated from a municipal wastewater treatment plant in Southern California that employed a conventional activated sludge treatment system followed by aerobic sludge digestion. Bio-solids from this system were selected for study because they had the lowest concentration of TCS among those collected from 10 different wastewater treatment plants in California . The soil and bio-solid physiochemical properties are reported in Table 1 and were determined using standard techniques . The soils were moistened to 40% water-holding capacity, which is equivalent to 18% water content in our experiments, and pre-incubated for 7 days at 25°C to allow time for normal microbial activity to recover to a constant level after disturbance. The pre-incubated 50 g of soil was weighed into 200 ml glass bottles to make three replicates per treatment. For the bio-solid amended soil sample, 20 mg/g of bio-solid was added. Each treatment sample was then spiked with TCS to achieve final concentrations of 10 or 50 mg/kg using TCS stock solutions prepared in acetone, as recommended by Waller and KooKana . This spiking level was chosen as a conservative upper bound on anticipated soil concentrations in the field. The lower spiking level is below the mean concentration observed in US bio-solids and the higher level is below the 95th percentile for US bio-solids ; adding bio-solids to soils at typical application rates would produce soil concentrations ~50–200 times lower. Control samples were also prepared with acetone only. After that, the solvent was allowed to evaporate inside the fume hood before the samples were thoroughly mixed. The microcosms were incubated in the dark at 25°C for 0, 7 and 30 days. Every week, each vial was opened to help keep conditions aerobic and the water content of each set of samples was measured and water was added as needed to maintain target moisture levels. At each sampling time, the remaining TCS was measured by drying 3–5 g samples at 70°C for 24 hours and homogenizing with a mortar and pestle. Replicate 1 g sub-samples of each dried sample were placed in centrifuge tubes, spiked with deuterated trichlorocarban in methanol, air dried under a fume hood to remove the methanol, and then mixed well. Extraction was performed by adding 15 mL of 1:1 acetone and methanol to the centrifuge tube. Samples were extracted on a shaker table for 24 hours at 295 rpm and 55 °C and then centrifuged for 30 min at 4,100 g. The supernatant was diluted as needed to ensure that the concentration remained within the linear portion of the calibration curve. The extracts were analyzed for TCS using LC-MS/MS. Additional details regarding the extraction and analysis procedures can be found in Ogunyoku & Young . As expected, the bio-solids contained far larger amounts of nitrogen and carbon than the Yolo soil . Even though the bio-solids constituted less than 2% of the amended soil, they contributed nearly 50% of the total nitrogen and 40% of the total carbon in the amended soil system. The bio-solids contained an abundance of nutrients accumulated as by-products of sewage treatment in forms likely to be more labile than equivalent nutrients present in the soil. As will be discussed further, the greater availability of C and N in the SB than soil treatments had a strong influence on some of the results, especially at the early time points. In the following section, therefore, it is useful to remember that all SB treatments contain more available C and N than all soil treatments. The initial concentration of TCS in unspiked SB samples was very low , fell below the quantitation limit for TCS after 7 days, and was not detectable after 30 days of incubation. Significant TCS bio-degradation was observed in spiked soil and SB samples during incubation and the data were well described using a first order model as indicated by linear plots of ln against time . Degradation trends were consistent at the two spiking levels for each sample type but bio-solid addition significantly reduced degradation rates at both spiking levels compared with un-amended samples. The percentage of TCS removed was approximately two times greater in soil than in SB samples. Approximately 80% of the TCS was removed over 30 days in soil treated with either 10 mg/kg or 50 mg/kg of TCS, but no more than 30% was transformed in the corresponding SB microcosms.

By using cohorts defined by narrow age groups, I am able to analyze how wages of such overall similar workers change as their cohort faces a higher rural out-migration shock. My investigation is challenged by the fact that information on the rural/urban status of a migrant’s locality of origin is not available in most population censuses and in the Brazilian censuses in particular. While the administrative region of a migrant’s origin may be known, these regions are often too large to meaningfully use data on population size or density to construct a proxy for the rural/urban status of the locality. In this paper I use the size of a cohort relative to a baseline year to measure rural net out-migration rates. More specifically a cohort’s rural out-migration in 1991 is measured as the change in the size of the cohort between 1980 and 1991. This net-migration method has been shown to perform well in the Mexico-US immigration by Martinez and Woodruff and Hanson and McInstosh. My empirical strategy is implemented using population census data from the Brazilian census of 1980, 1991 and 2000. The basic identification strategy is based on the fact that cohorts of workers have differential rural net out-migration rates and that these differences vary over time. I also address two key concerns about the potential sources of bias in the estimates. First, rural out-migration and wages may be simultaneously determined by, for instance,cut flower bucket pull factors such as urban employment growth or wages. Following the literature I apply an instrumental variables strategy using past rural out-migration rates as an instrument for current out-migration rates.

The results show that the instrument is strongly related to rural out-migration rates and reinforce the OLS estimates. Second, I address the issue of selectivity bias which arises because the measured wages in rural areas are obtained from selected workers who decided not to migrate. This is because, in the presence of self-selection into migration, rural out-migration may both reduce overall rural labor supply and affect the composition of rural labor supply. I show that the OLS and IV results are robust to controlling for key worker characteristics that may affect wages. Although addressing the issue only partially, this approach provides evidence that the OLS and IV results are robust to controlling for key characteristics that determine the composition of rural labor. My results show that a 10% increase in rural out-migration rate in a cohort raises wages in that cohort by 1 to 5%. This result suggests that rural out-migration flows in Brazil between 1991 and 2000 have increased wages by 3 to 6.5%. Moreover the impact on wages differs substantially by cohort. I find that rural out-migration between 1991 and 2000 led to a 4.5 to 5.6% increase in wages for the older cohorts of workers and between 7 to 9% for the younger cohorts. The remainder of this chapter is organized as follows: Section 2.2 provides an overview of the theoretical literature and presents the empirical framework. Section 2.3 describes the data, the basic results and some robustness checks. Section 2.4 discusses the issue of selection bias and changes in the composition of rural labor. Section 2.5 concludes.In this section I present the implications of existing models that could explain the effect of rural emigration on rural wages.

As discussed by Mishra, partial equilibrium models with closed economies suggest that, under certain hypotheses on the production function and uniform inputs, rural out-migration will raise real wages in rural areas leading to a welfare gain for workers, a welfare loss for owners of capital and an aggregate welfare loss. Models such as those in Findlay and Davis and Einstein extend the Ricardian model of international trade to allow for migration. In these models, under free trade, rural out-migration from will increase the real wage in rural areas in terms of the importable goods and remain unchanged in terms of the exportable good, leading to an increase of the real wage. However in the presence of a non-traded labor-intensive good, the real wages in rural areas could decrease with the degree of rural out-migration as shown in Quibria and Rivera-Batiz. This arises if migrants possess a large fraction of the capital or when there are increasing returns to the production of the non-traded good. Beyond the labor supply push, rural out-migration may also affect rural wages by increasing the rate of capital inflow. Remittances may increase consumption and investment of households at origin thus potentially raising local demand for goods and services and pushing prices and wages upward. In this paper I examine empirically how rural out-migration measured by changes in cohort size residing in a rural area affects the wage of rural workers in the same cohort. In light of the discussion above such analysis will measure, in general, the combined effect of changes in labor supply, capital inflow, and local demands for goods and services following a higher out-migration shock.

An important question is whether one can disentangle these effects or provide evidence on the main channels. The empirical model developed below presents a framework to estimate the effect of rural out-migration on rural wages. Due to the absence of data on rural capital stock, I assume that the stock of capital is fixed. As such, the results presented here provide long-run estimates of the effect of rural out-migration on rural wages in a general equilibrium setting. Where cohortsize is the size of cohort c living in rural areas of state s at time t. The variable shockemigrationcst measures the number of individuals which belong to cohort c of state s that have migrated out of rural areas as a share of the size of that cohort. The first issue is related to data limitations. While census data often includes information related to an individual’s migration status and administrative region of origin, they do not generally record whether the migrant was originally from a rural or urban area. Moreover, the administrative regions of origin are often too large to, meaningfully,flower display buckets use information on population size or density to construct measures of the rural/urban status of the locality of origin. The second issue is related to the identification of the effect of rural out-migration on rural wages. With information on individual’s migration status and rural/urban status of the locality of origin, one could measure the out-migration shock as the size of the rural locality residing elsewhere. However this will raise the concern that higher rural out-migration in a state could increase rural in-migration of individuals from other areas . Nonetheless while the approach in this paper deals with such concern, it doesn’t allow to separately estimate the effect of rural out-migration of native population and rural in-migration. The last issue is related to the definition of a rural area and whether this definition changes over time. In Brazil, the status of a locality as an urban or rural area is defined by municipal law and doesn’t adhere to any specific thresholds based on population size or density for instance. Moreover, the rural/urban status of localities did not change between the 1980 and 2000 censuses limiting concerns that rural/urban classification may be endogenous to living standards or wages. Lastly, the official rural/urban classification captures the differences in occupational structure that characterizes these two areas. In our sample over 80% of individuals residing in areas classified as rural are engaged in agricultural activities against 5% in localities classified as urban. Figure 2.1 shows smoothed densities of the measure of rural net out-migration in 1991 and 2000. Except for three states all states experienced net rural out-migration during this period. Our results are not affected by excluding the three states with positive net rural in-migration. Figures 2.2 to 2.8 show the distribution of out-migration by cohort. Both the theoretical and the empirical literature suggest that migration decisions are endogenous to wage differential between source and destination regions. As a consequence falling rural wages and job prospects in urban areas may lead to differential propensity to migrate across cohorts. To control for this reverse causality I instrument the emigration shock by lagged emigration shock .

This instrument is motivated by evidence on the importance of networks and social in migration decision . Since networks are usually based on blood relationship and friendship, our instrument which varies by cohort and state should be able to pick-up a large fraction of the movements in rural out-migration within the same cohort-by-state group. The data from my analysis are 5% random samples from the 1980, 1991 and 2000 Public Use Microdata Samples of the decennial census of Brazil. Unfortunately the 1980 census doesn’t contain reliable data on wages. However the 1980 census is used to construct the emigration shocks in 1991 and 2000. Individuals are divided in 7 cohorts using their age in 1991. The cohorts are individuals aged 20-24, 25-29, 30-34, 35-39, 40-44, 45-49 and 50-54 in 1991. The sample is restricted to individuals aged 20 to 54 in 1991 who earn between no less than 200 and no more 50,000 Reais per month in real terms which constitutes about 86% of the original sample. Table 2.1 reports basic summary statistics for the measure of rural net emigration shock and the logarithm of real monthly earnings. The degree of rural out-migration is considerable. In 1991, the rural emigrants shock was about 48% of the rural population. By 2000 this number increased to over 95%. In other words for every 100 individuals still living in rural areas in 2000, over 95 individuals had left rural areas since 1980. The emigrant shock is strikingly different across cohorts with the largest shocks appearing for the younger cohorts of individuals. Moreover these shocks are large compared to international immigration figures. By way of comparison Mishra finds that, in the case of MexicoUS migration, the largest immigration shock across skill groups is a little above 50% of the Mexican labor force. The real wages of individuals in the sample increased slightly between 1991 and 2000 despite several periods of hyperinflation. The increase in real wages range between 1.6 to 3.4 percentage points across cohorts with the largest increase occurring for the younger cohorts . As discussed by Mishra , in the presence of self selection of individuals into migration, the parameter estimated in equations and do not provide un-biased estimates of an exogenous change in rural labor supply. This is because, in the presence of self-selection into migration, rural out-migration affects rural labor markets in two distinct ways: a reduction in overall rural labor supply, and a change in the composition of rural labor supply. The instrumental variable strategy used in the analysis described above provides exogenous changes in rural labor supply but may not provide exogenous changes in the composition of rural labor supply. With pooled cross-sections I cannot model or control for individual’s self selection into migration. I provide some evidence that the results are robust to controlling for some of the observable characteristics of changes in workforce composition. I estimate again controlling for the share of a cohort that is male, with some primary education and that have completed primary education. The results from this estimation are reported in Table 2.4. Comparison the results in Table 4 to the coefficient estimates in columns to of Table 2 provides some indication on the robustness the previous results are to changes to workforce composition. I find that the OLS estimates are not affected by the educational attainment and gender composition of the population that remains in rural areas. However the IV estimates are lower by an order of 2 to 3 points of standard errors. This result is consistent with models of positive selection into migration, where out-migrants have a higher educational attainment and tend to be males. The results show that a 10% increase in out-migration increases rural wages by 1.4 to 2.1%. This suggests that after controlling for changes in workforce composition, the wage effect of rural out-migration flows between 1991 and 2000 drops from 6.5% to about 3%. This points to the fact that changes in workforce compositions resulting from higher rural out-migration could explain up to half of the effect of rural out-migration on rural wages.