Plastic flower pots – Nature Ecrogrow

Seeds were wrapped in foil and imbibed at 4°C for 4 days before planting

Since the negative short-term effects of Al on growth are apparently limited given that inhibition is alleviated without checkpoint function, conceivably these checkpoints have evolved to detect the minor strain on an individual’s genomic stability and serve to prevent transmission of Al-dependent genetic deffects to subsequent generations that ultimately would compromise the viability of the population. These checkpoints sacrifice the individual by halting the cell cycle in the root and forcing endore duplication to prevent an Al-dependent generational penalty with regard to heritable genomic integrity. Cells of the shoot meristem generate the floral reproductive organs of the plant, and thus the heritable genetic material. While the root is the most affected organ of the plant in the Al toxic response, Al is reallocated and sequestered to other regions of the plant body as Al-oxalate complexes can transport Al through the xylem from the roots to the shoots . In addition to a root hypersensitive phenotype, shoots of als3-1 grown in Al containing media display reduced cotyledon and leaf expansion, as well as a second shoot apex . Thus shoots are indeed affected by Al toxicity which could pose a threat to plant reproductive processes; therefore, it is plausible that Al-dependent root growth inhibition could serve as a means to preserve genomic integrity of the species. In all likelihood, it is plausible that Al induces an inappropriate activation of the DNA damage response by detecting Al-dependent pseudo-cross links. This could be the result of topological strain on the DNA and/or functional interference with Mg-dependent replication machinery,round nursery pots activating unnecessary repair of the DNA that may actually be the true detrimental effect of Al-dependent root growth inhibition.

Repair processes like nucleotide excision repair and nonhomologus end joining may be at work as shown by hypersensitivity to Al for loss-of function mutants in ALT2 and PARP1, PARP2 and KU80 respectively. The repair mechanisms could then result in subsequent damage inflicted on DNA, much of which may be related to double strand breaks that are regularly observed following Al treatment. The specific repair pathway activated in response to Al treatment is unknown, as well as whether or not this unknown process inflicts damage on the DNA during the repair. If indeed Al is acting to cause pseudo-cross links, it stands to reason that this effect would also inhibit proper DNA repair processes and could further cause damage to the DNA. As such, failure to activate this response pathway prevents the program-inflicted damage and results in roots that can grow normally in the presence of inhibitory levels of Al.While it is speculative at this time as to what the true nature of the effect of Al is on DNA integrity, an ATR-dependent DNA damage response pathway is clearly activated in the presence of internalized Al. Whatever the direct effect of Al is, based on the response factors, it can be speculated how these factors assemble and respond to Al stress based on their functional homology to related proteins: SUV2 likely aggregates at sections of persistent single stranded DNA coated by the heterotrimer, Replication Protein A, known to aggregate to single stranded DNA . SUV2 may act as a homodimer as it has been shown to bind to itself through its N-terminal coiled-coil domain as demonstrated by a yeast-2- hybrid . The proline-rich repeats at the N-terminus of SUV2 suggest a stiff elbow-hinge that could “wag” as a mechanism of recruiting other response factors to the locus.

It is possible that this homodimerization is controlled by phosphorylation of SUV2 since the dimerization domain has two SQ phosphorylation motifs associated with it. SUV2 would act to recruit ATR to this region of DNA in a manner similar to their homologues in yeast and mammals . The interaction of SUV2 and ATR with persistent single stranded DNA should induce autophosphorylation of ATR, and phosphorylation of SUV2 by ATR. It is possible that ATR will also be phophorylating other substrates, such as RPA2 and H2AX, to orchestrate additional responses. Once ATR has activated these sensors, likely in conjunction with other unidentified proteins, they would then induce the signal transduction pathway by activation of SOG1, again, likely through phosphorylation by ATR. Conserved serine-glutamine motifs are preferential ATM and ATR phosphorylation targets in mammals . SOG1 has five SQ motifs in the C-terminal transcriptional activation domain and SUV2 has two SQ motifs near the N-terminus, one of which is within the dimerization domain. Following activation of SOG1, expression of a group of genes is promoted, specifically genes tested from an established set of SOG1-mediated genes involved in a DNA damage response. This subset of Al-induced SOG1 mediated genes includes genes known to repair DNA e.g. BRCA1, RAD51, RAD17, GMI1, and PARP2 and halt the cell cycle e.g. CYCB1;1 as well as more transcription factors e.g. TRFL10,TRFL3, ANAC103 and WRKY25. Perhaps it is these transcription factors, as well as unidentified genes promoted as part of this response that are responsible in some unknown manner for a mechanism that forces a programmatic change in the root tip and QC, thus triggering this tissue to switch to endore duplication and causing terminal differentiation and permanent stoppage of growth of the primary root. While little is known about the placement of ALT2 within this signal transduction pathway, it likely functions as a scaffold protein, perhaps as part of a ubiquitin ligase signaling mechanism, acting analogously to other WD-40 proteins. WD40 repeat proteins are a class of proteins that are generally involved in mediating interactions between other proteins, associating with a variety of protein complexes, including E3 ubiquitin ligases . In eukaryotes, proteins are targeted for degradation via the ubiquitination-proteasome system, but ubiquitination also plays an important role in post-translational modification of proteins in the activation of signaling pathways.

As part of a crucial step in the DNA damage response pathway in mammals, following phosphorylation by ATM or ATR, one of the core histones of the nucleosome, γ-H2AX, is mono-ubiquitinated. This mono-ubiquitination is required for the recruitment of subsequent repair factors like BRCA1 and 53BP1 to both double and single stranded DNA breaks . In plants, CULLINs , which are part of a family of scaffolding proteins, form the largest family of E3 ligase complexes. Arabidopsis proteins containing WD40 domains, including ALT2, are proposed to be capable of interacting with the DDB1-CUL4-ROC1 complex . The recruitment structures and mechanisms are not well understood for CULLIN based ubiquitination signaling; however,plastic flower pots CUL4 has been shown to form a complex with DW40 proteins in response to UV damage that is ATR dependent . This establishes a potential link between ATR and ALT2 in a DNA damage response where resulting cross links would cause a replication fork stall, as Al likely causes.A model for stoppage of root growth following chronic exposure to Al can be developed in accordance with current evidence. In this model, Al impacts DNA in a currently unknown way, likely from a pseudo-cross linking effect resulting in a replication fork stall. Based on the genetic factors responsible for activating the Al dependent DNA damage response, it is a reasonable prediction that such an interaction would hold DNA in a conformation that inhibits replication fork progression. Regardless of the physical consequences of Al on DNA structure or integrity that have yet to be determined, the predicted genotoxic effects of Al are clearly sufficient to activate an ATR-, ALT2-, SOG1- and SUV2-dependent cell cycle checkpoint mechanism as demonstrated by the increase in Al tolerance seen for each loss-of-function mutant. This mechanism functions to promote transcription of a group of genes related to halting the cell cycle and to repair the perceived damaged DNA. Furthermore, it is likely that additional genes are included in this transcriptional response that are related in some unknown manner to a mechanism that forces a programmatic change in cells of the root tip and especially the QC. These genes would trigger cells to differentiate, losing their meristematic identity by switching from a normal cell cycle progression to endore duplication. Ultimately, it is this terminal differentiation that permanently stops growth of the primary root as the primary cause of Al toxicity. While significant work remains to be done, especially in determining the genotoxic consequences of Al that activate this DNA damage response pathway and developing a transcriptional profile of SOG1 targets that lead to inhibited root growth following Al treatment, it is clear that terminal differentiation of the root tip following chronic exposure to Al is an active event mediated by the DNA damage checkpoint factors ATR, ALT2, SOG1 and SUV2. Our understanding of the genomic consequences caused by Al is still in the beginning stages, and more work is needed.

Continued testing of DNA damage response mutant responses to Al can give us the opportunity to further elucidate how genomic maintenance factors are involved in this biological problem. In addition to the value of gaining a better understanding of the role of DNA damage response factors and cell cycle checkpoints in mediating Al-dependent DNA damage, Al toxicity represents a novel and biologically relevant model for studying ATR dependent mechanisms in the DNA damage response in general.For all growth experiments, seedlings were surface sterilized, vernalized, and etiolated before planting. Seeds were immersed in 70% ethanol and then washed 4 times with sterile water. Seeds were then immersed in 50% bleach for 5 minutes, after which seeds were washed 4 times with sterile water. The AlCl3 soaked gel environment was sterilely prepared by pouring a lower gel layer consisting of 80 mL of nutrient medium plus 0.125% gellan gum in Nunc Lab-Tek Extra-Depth Polystyrene Dishes 100 x 25 mm . Nutrient medium consisted of 2 mM KNO3, 0.2 mM KH2PO4, 2 mM MgSO4, 0.25 mM 2SO4, 1 mM Ca2, 1 mM CaSO4, 1 μM MnSO4, 5 μM H3BO3, 0.05 μM CuSO4, 0.2 μM ZnSO4, 0.1 μM CaCl2, 0.02 μM Na2MoO4, 0.001 μM CoSO4, and 1% sucrose. Al was introduced by overlaying the solidified lower layer with 20 mL of “soak solution” containing the proper concentration of AlCl3. Trail soak solution was made consisting of the nutrient solution medium described above, while only brought to 90% of the intended volume. 50 mL trail solutions were made consisting of 45 mL the slightly concentrated nutrient medium, X mL 25mM AlCl3, Y μL 0.1 N KOH and Z mL diH2O . The trail soak solution was made to determine the amount of 0.1 N KOH to use to adjust the pH of the nutrient soak containing AlCl3. The amount of base to add was determined empirically by adjusting the pH on an aliquot of the soak solution containing AlCl3. The amount of base determined from this trial soak solution was added to the actual soak solution prior to adding AlCl3. The sterilized soak solution was allowed to equilibrate with the lower layer for 2 days and was then poured off. This method was used for all concentrations of AlCl3 for plants grown in a gel soaked environment. In hydroponics experiments, Al-screening media was sterilely prepared as above without gellan gum and AlCl3. Seeds were sowed on 250-μm mesh, polypropylene screen in Parter Medical Products Quad Perti Dish 100 X 15 mm . After 6 days of growth unless otherwise specified, screens were transferred to new Al screening media supplemented with either 0 μM, 25 μM AlCl3 or 50 μM AlCl3. For treatment with hydroxyurea , mitomycin C , bleomycin , or cisplatin were added to plant nutrient media plus sucrose . Seeds were sowed and allowed to grow for seven days, after which roots were measured. For experiments on plant nutrient media plus sucrose , the medium consisted of 5 mM KNO3, 2.5 mM KH2PO4, 2 mM MgSO4, 2 mM Ca2, 50 μM FeEDTA, 1 μM MnSO4, 100 nM CaCl2, 100 nM CoSO4, 5 nM H3BO3, 50 nM CuSO4, 20 nM NaMoO4, 0.8 M Sucrose, 0.8% agar. Plants were grown in 24-hour light at 20°Cin I-36LLVL biological incubator . After one week, plants were repotted in Sunshine Special Blend potting soil with controlled release fertilizer, 15-9-12 + minors . Plants were grown in 24- hour continuous light at 22°C in a plant growth room with Sylvania Gro-Lite fluorescent bulbs until maturity.

Young’s interpretation differs from GLW in emphasizing the role of selective migration across sectors

However, the mechanisms underlying environmental impacts on preterm delivery are still insufficiently understood and further experimental research is warranted. Pesticide exposures affected preterm birth in our study mostly in female children and to a lesser extent if at all males, similar to a Chinese study that found high levels of non-specific metabolites of organophosphate pesticides in maternal urine to have adversely affected duration of gestation only in girls . It has been suggested that exposures to pesticides in early pregnancy trigger more spontaneous abortions of male fetuses , or stillbirth in late pregnancy , outcomes not captured in our study. It is well known that the male fetus is more vulnerable in utero and is at greater risk of fetal death with the male-to-female ratio falling from around 120 male conceptions to 105 boys per 100 girls at birth . Some pesticides are endocrine disruptors such as those in the organophosphate family that mimic sex steroidal action and resemble estrogenic more than androgenic action in fish models . In general, we observed stronger ORs among infants born to Hispanic mothers partly because Hispanic mothers had higher exposure prevalence during pregnancy. According to a recent agricultural survey, about 90% of female farm workers in California were Mexico-born Hispanics ; thus, the foreign-born Hispanic mothers may live near fields where they work, making them more likely to be exposed to ambient pesticides when at home. Unfortunately,plastic flower pots information of specific occupations and occupational addresses of the mothers was not collected on birth certificates and therefore we could not determine exposures at workplaces.

Fetal growth restriction, the main reason for low birthweight other than preterm birth, has been associated with transplacental oxygen and nutrient transport, hypoxia, oxidative stress, placental inflammation, and inhibition of placental growth hormone ; these possible mechanisms may be influenced by toxic exposure to organophosphate and carbamate pesticides . We did not find much evidence for associations between term low birthweight and many specific pesticide exposures, in line with some previous studies. Others however, reported associations for low birthweight or a decrease in birthweight for some pesticides, including chlorpyrifos and/or diazinon, carbaryl, methyl bromide, as well as with organophosphate and pyrethroid metabolites measured in maternal urine . However, it also has been reported that when adjusting for gestational age associations with low birthweight were attenuated . Our results for pyrethroids are consistent with these previous observations for both preterm birth and low birthweight. Our term low birthweight results may have been under powered but still seem to corroborate a previous report that found residential proximity to methyl bromide use to reduce birthweight overall . Most previous pesticide and birth outcome studies examined exposures from home/garden or professional use of pesticides and relied on parental interviews after birth; these studies have been criticized for their potential selection or recall bias . Other studies using job exposure matrices may have been prone to non-differential exposure measurement errors, and often could not distinguish between types of chemicals. Smaller studies were able to employ biomarkers such as maternal blood or urine collected in pregnancy, or umbilical cord blood samples to measure prenatal chemical concentrations . The necessarily small size of such pregnancy cohorts limits the number of outcomes and hence study power considerably, and they also have to assume that chemical concentrations measure in bio-samples reflect exposures during multiple gestational windows accurately when many pesticides have relatively short half-lives, e.g., hours to a few days for organophosphates , and few studies have multiple bio-samples available throughout pregnancy.

Recently, several studies have examined the associations of ambient pesticide exposures and adverse birth outcomes in large populations based on proximity to applications modeling . These GIS-PUR based approaches applied to birth records avoids selection bias due to non-response and recall bias that threatens studies relying on interviews after births, in which mothers who had babies with adverse outcomes may be more likely to participate or recall their pesticide exposures. Similar to ours, these Californian studies were exclusively based on California’s PUR records and land use surveys. Particularly, two studies focused on the agriculturally dominated San Joaquin Valley; one assessed exposures by comparing high exposure to low exposure to pesticides with acute toxicity based on EPA signal word, while the other that reported negative associations with spontaneous preterm birth focused on exposures to frequently used chemicals and physicochemical groupings yet they mainly reported results by month in late pregnancy. Our sensitivity analysis stratified by season of conception supported our hypothesis that early but not late pregnancy is the critical period. Besides, different from previous studies, our method employed a four-tier mechanism to improve the match rate of PUR and land use maps , successfully reducing potential non-differential misclassification of exposure. We also expanded the study area to the California statewide to include more agricultural regions that might also be populous outside of the Central Valley while providing us with a large sample size and thus high statistical power in this record linkage-based design. Our study has some limitations. The ambiguous location, only at county level, of those non-agricultural pesticide applications in pesticide reporting, made it difficult to properly assess exposures for mothers living in urban areas at birth, whom were excluded to avoid substantial underestimation of exposure. However, our restriction to women living within 2km of fields might partially and indirectly ‘matched on’ location and generated a more homogeneous population in terms of potential geographically-specific confounders such as air pollution.

Similarly, since our study question is whether proximity to fields with agricultural pesticide applications increases risks of adverse birth outcomes, despite that other unassessed sources of pesticide exposure including occupational, home and garden use, or dietary exposures to pesticides could potentially confound our results, our ‘matching’ through restriction to women living within 2km of fields might have accounted for such factors. For example, the SUPERB study in northern California suggested that those who live near fields are more similar in their use of pesticides for other purposes, than residents in urban areas . Residents in the San Francisco metropolitan area, had a lower percentage of using outdoor pesticides than two inland areas in northern California they studied . Another assumption was that addresses at birth reflected the location of mothers over the entirety of pregnancy. A review of research on residential mobility during pregnancy showed that on average 24% of mothers move during pregnancy in the US ; although most moving distances were short , it may result in exposure misclassification in our GIS-based estimates based on a 2km buffer. Particularly, Hispanic mothers are more mobile than White mothers , increasing their chances of living close to the fields and receiving pesticide exposures during pregnancy. Similar to all other studies of live birth outcomes ours may also be subject to live birth bias, i.e., the fact that early exposures could lead to fetal loss. While data on the potential confounders maternal smoking and pre-pregnancy BMI, was only available for 4 out of 13 years of our study period, additional adjustment for these variables did not change our results more than minimally and suggests that they may not be confounders. In summary,plastic garden container this study found that first and second trimester exposures to most selected pesticides known or suspected to be reproductive toxicants were associated with preterm delivery but only one pesticide and perhaps pyrethroids as a class and were related to term low birthweight in California among women living near agricultural fields in California. These associations seemed stronger for female infants suggesting possible sex specificity for some of these agents.Epidemiologic studies of environmental exposures in early childhood, often assign exposures based upon the child’s or mother’s residence. While large-scale record-linkage based studies can avoid selection and recall bias that often impacts smaller studies with active subject recruitment, previous record-based studies often relied solely on maternal residential address at birth, which is readily available on many birth certificates and/or residential address at diagnosis, as done in some childhood cancer studies . The reliance on one address implicitly makes the assumption that a child’s residence remains the same throughout early childhood, or if they moved, that the exposure levels remained the same. Consequently, this may lead to exposure mis-classification for those who move in early childhood especially for exposures with high spatial heterogeneity. In a 2003-2007 California statewide representative survey, only 14% of all women moved in the 2-7 months post-partum , but with increasing age the frequency of residential moves also increased. For more than 50% of childhood cancer cases under age 5 diagnosed in California between 1988 and 2005, address at birth differed from the address at cancer diagnosis , which raises concerns about using residence at birth to assess exposures in early childhood. Exposure misclassification due to moving is a ubiquitous problem encountered by nearly all record-based studies that lack a complete residential history for each child. Previous studies suggested that residential mobility may be associated with certain risk factors for childhood cancers such as maternal age, marital status, parity, family income, and other socioeconomic status metrics , resulting in differential misclassification of exposures. While previous studies that examined residential proximity to exposure have mentioned the potential bias resulting from residential mobility during pregnancy , they rarely investigated the impact of residential mobility in early childhood on exposure measures or effect estimates.

While it is not feasible to acquire complete residential histories from interviews for subjects in large record-based studies as a gold standard to compare against the recorded birth or diagnosis address, databases containing public records of individuals collected by commercial companies have become available in recent years, allowing us to trace individuals without a self-reported residential history. For example, LexisNexis® Public Records , a commercial credit reporting company, provides all known addresses for a set of individuals upon request. Earlier validation studies have proven addresses acquired from LexisNexis to be useful for reconstructing residential histories for subjects in epidemiological studies with an overall match rate of ~70-85% with detailed address history obtained from interviews ; however, these subjects mostly consisted of mid-aged or older individuals, whose residential mobility may differ from that of women at child-bearing age. Such information, if of high quality, could potentially augment existing address information and help us to reconstruct residential histories for subjects in large record based studies and provide more accurate exposure estimates. The degree of exposure misclassification due to mobility depends on the distance moved, the spatial heterogeneity of the exposure , and the method of exposure assessment each study employed. For example, one study used ecological measures of agricultural activity at the county level , thus moving within a county would not alter exposure estimates. Other studies have assessed agricultural land use and crop coverage within a 1-km buffer of a child’s residence as proxies of pesticide applications or exposures to pesticides within a ½ mile buffer of child’s residence in relation to childhood cancers; such individual-level measures might be more sensitive to changes in location. Compared with these methods to estimate agricultural pesticide exposures near residences, our GIS-based system that integrates California’s unique Pesticide Use Reporting database and land use maps in California estimates children’s early life exposures at a finer resolution, but may be subject to more misclassification due to residential mobility. For the purpose of this study, we identify individuals’ exposures in early childhood using a 2-km buffer. The objectives of the present study are to assess patterns of mobility and identify maternal and child characteristics that may predict residential mobility in early childhood, and examine the impact of mobility on early childhood exposure measures for agriculturally applied pesticides and childhood cancers in California.To examine the associations between maternal and child characteristics and the cases’ likelihood of moving between birth and diagnosis, we conducted univariate and multivariate logistic regression analysis and estimated odds ratios and 95% confidence intervals . Based on previous literature , we considered factors that potentially influence mobility in pregnancy or early childhood including age at diagnosis , year of birth , maternal age at delivery , maternal race/ethnicity , maternal birthplace , maternal education , parity , rural/urban classification of residence at birth , and several socioeconomic variables including payment source for prenatal care as a proxy for family income and neighborhood level SES.