Geochemical characteristics have an important influence on HM plant uptake. Future investigations can focus on the interactions between trace elements or other factors that may demonstrate an influence on HM plant uptake. Forage and water intake are important considerations in livestock, and soil ingestion must also be considered. In the current examination, the soil samples showed greater HM concentration than sheep tissue and forage samples. It has been demonstrated that sheep, a ground feeding animal, eat one to two percent of soil when good forage is available and about 18% when low quality forage is available. It has been shown that sheep intake and digestibility of more mature plant material decreases with advancing maturity due to greater effort and time in chewing by the animal; sheep selectively graze in high-quality forage areas when they are available. The forage environment of the sheep in the current study area exhibited high stocking rates, sparse vegetation, and mature forage samples, which may have contributed to higher HM concentrations in forage. Dung analysis can evaluate the amount of inorganic material in sheep diets and may be useful in future studies in the current study area. Previous studies have reported the concentrations of HMs in sheep tissues, plants, and soil in the target study area . In most categories, our study results were comparable to or less than what was previously found. The current study tissue measurements were below the exposure and control concentrations reported by Millard et al. and Ruttenber et al. in the 1980s. No excess cancer risk was calculated to be attributed to eating sheep meat, liver, kidney, and soup bone by humans; researchers recommended continued monitoring at that time. The highest HM metal concentration in the diet was used for each animal to calculate and compare to the maximum tolerable concentrations, and the lowest concentration for each HM was used to compare to the requirements for Mo and Se. The calculations are based only on the forage samples collected and are not representative of the complete sheep intake. Maximum tolerable concentrations are established for sheep intake for As Cd, Pb, Mo, and Se. All study animals did not exceed the calculated maximum tolerable concentrations for As, Cd, Mo, and Pb.
All study sheep met the Mo and Se dietary requirements. Liver is the organ of choice to diagnose Se deficiency,vertical garden indoor and concentrations less than 0.21 mg/kg in sheep liver are considered deficient. All study sheep liver concentrations did not indicate deficiency. In sheep, Se toxicity was reported at 0.25 mg/kg of body weight chronically. However, the National Research Council set the maximum tolerable concentrations for Se at 5.0 mg/kg of DM. Of the donated sheep, the shepherds did not report indicators of acute or chronic Se poisoning . Other supplementary sources of forage were not reported at the time of sampling; sheep harvesters reported relying on alternative fodder sources for their sheep in the late winter months only . New Mexico is one state that was reported to have high Se concentrations in soils and those in areas with low annual rainfall or alkaline soil. The mean study soil pH was 7.31 ± 0.51. Primarily, most of the Se is absorbed in the small intestines of ruminants and less absorption is seen in forage based diets versus diets based on concentrate. Plants that accumulate Se may be unpalatable to grazing animals, but if there is lack of more palatable forage, animals may develop signs of toxicity from ingestion. According to one study calculation, selenosis can occur in lambs ingesting 0.2% BW of Se accumulating plants. Soil ingestion during foraging, seasonal soil forage adhesion , pulling up of roots while foraging, and licking snouts by livestock may also contribute to higher HM concentrations. The forage plants that we sampled were not known Se obligate or secondary accumulator plants. Aside from Se, whether study plants accumulate Mo and Cd needs further evaluation. Selenosis diagnosis is primarily based on Se measurements , anemia and the presence of physical examination findings identifying toxic levels. Selenium concentrations in the liver and kidneys were not elevated on a DM basis. One source reported that plant forage containing >3–5 mg/kg induced toxicity in sheep. In our study, several plant roots exceeded 3 mg/kg, which is a concern with the pulling up of roots when sheep forage. The amount of root consumption in relation to the total sheep forage intake is important to determine. Further work examining these factors is an area of future research. Based on drinking water standards for livestock, none of the heavy metal concentrations were above maximum tolerable concentrations. Heavy metal water measurements collected by the DiNEH study from two of the water sources identified for Sheep 3 contained lower concentrations of Pb in comparison to our data ; the remaining HM data were less than what the DiNEH researchers found.
Most of the shepherds obtained public water for sheep consumption, which was reflected in the concentration levels found in sheep water. Harvesters in the study reported a history of consuming unregulated water intended for livestock. However, the As, Cd, Pb, Se, and U concentrations did not exceed the maximum contaminant levels set for human consumption. The implementation of water use maps may have contributed to the use of safer alternative water sources for these shepherds. Continued emphasis on the use of safe alternatives for water use in sheep and human consumption put forth by deLemos et al. is essential. Harvested food selling and sharing was common among the participants in the study. Emphasis should be placed on determining the incidence and frequency of food selling and sharing when assessing food chain contamination. Harvesting locations and activities can overlap in mining impacted areas. A few important factors to consider include the availability of harvest items based on seasonal variation and peak consumption periods . It is important to consider the consumption of contaminated food not only by individuals and their families but potentially the whole community and beyond. Studies identified mutton as a core food staple, comprising 6% of the total energy and 10% of the total protein consumed in the Diné diet. The current study participants reported that 35% of their total protein meat intake is comprised by local O. aries. The mean intake of local sheep protein was reported to be one day per week. In the study community, the typical serving size per foodstuff is reported to be 76.54 g of sheep muscle protein, roasted or boiled whole liver 377.5 g, roasted one whole kidney 76 g, and roasted or boiled lung 111.5 g. Using the typical serving size for each food stuff, we used the maximum HM concentration for each food item to calculate the weekly intake of HM from the current diet of the study population. The calculations for Mo and Se are based on the information provided by harvesters and are reflective of the sheep meat average consumption of one day per week. The Recommended Dietary Allowance for Mo was exceeded by more than a factor of 2 but, but the tolerable upper intake limit was not exceeded. The liver alone exceeded the Mo RDA by a factor of 1.8. By our estimates, an individual would have to consume half of the typical serving size to meet the RDA. The Mo levels in all sheep food products consumed comprised of 4.6% of the UL. The Se Reference Dietary Intake for adult males and females is 55 µg per day, and the Tolerable Upper Intake level is set at 400 µg/day. For all sheep products,vertical garden indoor system the harvesters exceeded the Se RDI by more than a factor of seven and were slightly below the tolerable upper intake level of 400 µg/day.
The liver protein intake alone comprised 80% of the tolerable upper limit of Se. Hypothetically, if one consumes liver protein more than once a week in the current scenario, the Se UL will be exceeded. The reported values only take into account the levels representative of sheep protein intake evaluated in this study and exclude non-subsistence and other dietary sources. In summary, in this U mining impacted area, our calculations indicate that the Se levels found in locally harvested sheep exceeded the RDI significantly but were marginally below the established daily tolerable upper intake level. Similarly, the RDA for Mo was exceeded, while the Mo UL was not exceeded. Consuming liver once a week has exhibited exceedances in Se RDI and Mo RDA, and it is anticipated that eating more than one serving size of liver per week would cause one to exceed the Se UL. Diversification of the overall dietary intake or minimizing the intake of high HM content foods are recommended until further research can be done. Our study was comprised of adults only; therefore, our calculations are based exclusively on adult food intake. Recommendations based on tailored research are needed for those that are more sensitive to HM exposure such as children, the elderly, pregnant women, or those with at risk health conditions. There is no dietary intake guideline for the remaining HM examined in this study.The results of this study need to be generalized with caution as the sheep sample sizes were small. Further, the sheep samples were collected from two communities that were near in distance. Still, geographical dissimilarities were apparent between the two communities. Plant heavy metal contamination levels evaluated both surface contamination and plant uptake. As this was a food chain study, we strived to examine the HM concentrations available to the primary meat staple. Comparable differences in HM levels were found in controlled and field studies utilizing unwashed plant samples. Over 30 years ago branched β-1→3-glucans and the EP – AA and EPA – were characterized as potent oomycete elicitors of innate immune responses in plants. These and the Phytophthora elicitin proteins with activities in a somewhat narrower host range figured prominently in the literature in subsequent years, and were used to examine physiological, biochemical and molecular events associated with the HR and induced resistance. Intriguing is that β-glucans and EP are important in modulating innate immunity and inflammation in animals, although these cross-kingdom parallels are likely not fully appreciated by the plant and animal research communities. Oomycetes are among the most important plant pathogens, responsible for devastating plant diseases worldwide.
New Phytophthora species, in particular, are continually being discovered, with the number of species identified nearly double that of only a decade ago . Downy mildew pathogens and the diseases they cause are also current threats to U.S. and world agriculture, with two listed as Select Agents as serious threats to U.S. agriculture . The Phytophthora research community is attuned to the need and urgency to develop novel control strategies that are broadly applicable yet sustainable, with vigorous research programs studying population genetics, genomics, effector biology, host resistance, and disease epidemiology and management. Within this research portfolio, determining how β-glucans and EP are perceived and act in plants could be useful for enhancing disease resistance against oomycetes and possibly other attackers. In this review, we highlight early studies of β-1→3- glucans and EP, discuss their roles as evolutionarily conserved signals, and consider their action in relation to current models of MAMP1-triggered immunity.Arachidonic acid and eicosapentaenoic acid are 20-carbon, all-cis PUFAs containing four and five double bonds, respectively . In mammals, AA and EPA undergo enzymatic oxidation to oxylipins, referred to as eicosanoids, which serve crucial signaling functions in stress responses . Examples of these eicosanoids include prostaglandins and thromboxanes, formed via the action of cyclooxygenases, and leukotrienes, formed via the action of LOXs. Eicosanoid-mediated stress responses include pain, inflammation and fever , platelet aggregation and vasoconstriction , and allergic responses and asthma . Although higher plants do not contain AA and EPA, AA and EPA are found in oomycete pathogens and plants are exposed to these fatty acids during infection . Many molecules of microbial pathogens identified as elicitors in earlier studies have been reclassified as MAMPS to conform to terminology used in animal immunity. MAMPs are motifs in essential molecules such as proteins, lipids, and polysaccharides that are present in entire classes of microbes . These molecular motifs are generally absent from hosts and can be recognized by plants and animals, such as in response to attempted infection or colonization.