Microbial and size characterization of airborne particulate matter collected on sticky tapes along US-Mexico border.

Particulate matter (PM) emissions from various sources can affect significantly human health and environmental quality especially in the Chihuahuan Desert region along US-Mexico border. The objective of this study was to use the low-cost sticky tape method to collect airborne PM for size characterization and identification of fungal spores. Sticky tape samplers were placed at 1.0 and 2.0m above the ground surface at experimental sites in Ciudad Juárez, Mexico and at 0.6, 1.2 and 1.8m at New Mexico sites, USA. Soil samples were collected in both countries to determine fungal diversity, texture and moisture content. Dust particles collected from all of the experimental sites had a dominant texture of clay (<0.002mm). The dominant textures identified from soil samples collected from the US and Mexican sites were loam and sandy clay loam, respectively. Alternaria, Penicillium and Fusarium were frequently found funguses in the US sites while Alternaria and Aspergillus were commonly observed in the Mexican sites. The sticky tapes also showed a similar diversity of fungal microorganisms present in the airborne PM at both Mexico and US sites. Alternaria, Penicillium and Aspergillus were the three groups of airborne fungal microorganisms consistently present in the US and Mexican sites. The low-cost sticky tape method has the potential to be used for characterizing different airborne microorganisms and dust particles.

Environmental Effects of Nanoceria on Seed Production of Common Bean (Phaseolus vulgaris): A Proteomic Analysis.

The rapidly growing literature on the response of edible plants to nanoceria has provided evidence of its uptake and bioaccumulation, which delineates a possible route of entry into the food chain. However, little is known about how the residing organic matter in soil may affect the bioavailability and resulting impacts of nanoceria on plants. Here, we examined the effect of nanoceria exposure (62.5-500 mg/kg) on kidney bean (Phaseolus vulgaris) productivity and seed quality as a function of soil organic matter content. Cerium accumulation in the seeds produced from plants in organic matter enriched soil showed a dose-dependent increase, unlike in low organic matter soil treatments. Seeds obtained upon nanoceria exposure in soils with higher organic matter were more susceptible to changes in nutrient quality. A quantitative proteomic analysis of the seeds produced upon nanoceria exposure provided evidence for upregulation of stress-related proteins at 62.5 and 125 mg/kg nanoceria treatments. Although the plants did not exhibit overt toxicity, the major seed proteins primarily associated with nutrient storage (phaseolin) and carbohydrate metabolism (lectins) were significantly down-regulated in a dose dependent manner upon nanoceria exposure. This study thus suggests that nanoceria exposures may negatively affect the nutritional quality of kidney beans at the cellular and molecular level. More confirmatory studies with nanoceria along different species using alternative and orthogonal "omic" tools are currently under active investigation, which will enable the identification of biomarkers of exposure and susceptibility.

Different forms of copper and kinetin impacted element accumulation and macromolecule contents in kidney bean (Phaseolus vulgaris) seeds.

The relationship between engineered nanomaterials and plant biostimulants is unclear. In this study, kidney bean (Phaseolus vulgaris) plants were grown to maturity (90 days) in soil amended with nano copper (nCu), bulk copper (bCu), or copper chloride (CuCl2) at 0, 50, or 100 mg kg-1, then watered with 0, 10, or 100 µM of kinetin (KN). Seeds were harvested and analyzed via ICP-OES and biochemical assays. While seed production was largely unaffected, nutritional value was significantly impacted. Accumulation of Cu was enhanced by 5-10% from controls by Cu-based treatments. Fe was the only macro/microelement significantly altered by nCu, which was ~29% lower than seeds from untreated plants. All forms of Cu combined with 10 µM KN reduced Mg from 9 to 12%. Application of KN plus bCu or CuCl2 elevated concentrations of Mn (31-41%) and S (19-22%), respectively. Protein content of seeds was stimulated (11-12%) by bCu, on average, and depressed by CuCl2 + KN (up to 22%). Variations in sugar and starch content were insignificant, compared to controls. Our results indicate that the interaction Cu × KN significantly altered the nutritional value of common beans, which has potential implications to agricultural practices incorporating Cu as either a pesticide or fertilizer.

Investigation of potential zooanthroponotic transmission of cryptosporidiosis and giardiasis through agricultural use of reclaimed wastewater.

A field study in the Juarez Valley of Mexico was performed to investigate the potential transmission of Cryptosporidium and Giardia to sheep livestock grazing on forage irrigated with reclaimed wastewater, and the potential for disease transmission back to humans. United States Environmental Protection Agency Method 1623 immunofluorescent assay (IFA) revealed high levels of pathogens in reclaimed wastewater, with 183 to >7000 Giardia cysts and 9 - 762 Cryptosporidium oocysts detected per litre. Infectious Cryptosporidium were detected in the reclaimed wastewater using the cell culture focus detection method (FDM). Polymerase chain reaction (PCR) analyses revealed reclaimed wastewater contained the C. parvum bovine (zoonotic) genotype, human-specific C. hominis subgenotypes, and G. lamblia (syn. G. duodenalis, G. intestinalis) Assemblage A genotypes (A2 and A3). Despite high levels of Cryptosporidium and Giardia in the reclaimed wastewater, these pathogens were rarely found on the forage plants, possibly due to environmental attenuation. Sheep fecal specimens were positive for only livestock-associated G. lamblia Assemblage E genotypes. Therefore, in this field study, there was no evidence of zooanthroponotic transmission of Cryptosporidium or Giardia.