Project description:Atrazine is an agricultural herbicide used throughout the Midwestern United States that frequently contaminates potable water supplies resulting in human exposure. Using the zebrafish model system, an embryonic atrazine exposure was previously reported to decrease spawning rates with an increase in progesterone and ovarian follicular atresia in adult females. In addition, alterations in genes associated with distinct molecular pathways of the endocrine system were observed in brain and gonad tissue of the adult females and males. Current hypotheses for mechanistic changes in the developmental origins of health and disease include genetic (e.g., copy number alterations) or epigenetic (e.g., DNA methylation) mechanisms. As such, in the current study we investigated whether an atrazine exposure would generate copy number alterations (CNAs) in the zebrafish genome. A zebrafish fibroblast cell line was used to limit detection to CNAs caused by the chemical exposure. First, cells were exposed to a range of atrazine concentrations and a crystal violet assay was completed, showing confluency decreased by ~60% at 46.3 µM. Cells were then exposed to 0, 0.463, 4.63, or 46.3 µM atrazine and array comparative genomic hybridization completed. Results showed 34, 21, and 44 CNAs in the 0.463, 4.63, and 46.3µM treatments, respectively. Furthermore, CNAs were associated with previously reported gene expression alterations in adult male and female zebrafish. This study demonstrates that atrazine exposure can generate CNAs that are linked to gene expression alterations observed in adult zebrafish exposed to atrazine during embryogenesis providing a mechanism of the developmental origins of atrazine endocrine disruption.
Project description:In this study, two multiantibiotic-resistant bacteria, Ochrobactrum intermedium (N1) and Stenotrophomonas acidaminiphila (N2), were isolated from the sludge of a PWWTP in Guangzhou, China. Whole-genome sequencing revealed that N1 and N2 had genome sizes of 0.52 Mb and 0.37 Mb, respectively, and harbored 33 and 24 ARGs, respectively. The main resistance mechanism in the identified ARGs included efflux pumps, enzymatic degradation, and target bypass, with the N1 strain possessing more multidrug-resistant efflux pumps than the N2 strain (22 vs 12). This also accounts for the broader resistance spectrum of N1 than of N2 in antimicrobial susceptibility tests. Additionally, both genomes contain numerous mobile genetic elements (89 and 21 genes, respectively) and virulence factors (276 and 250 factors, respectively), suggesting their potential for horizontal transfer and pathogenicity.
Project description:Large amounts of carbon sequestered in permafrost are becoming available for microbial degradation. We investigated 1,529 microbial metagenome-assembled genomes recovered from our site to understand carbon processing in this environment. Metabolic reconstruction, supported by metatranscriptomic and metaproteomic data, revealed key populations involved in organic matter degradation, including bacteria encoding a pathway for xylose degradation only previously identified in fungi.
Project description:Atrazine, a herbicide commonly applied to agricultural areas and a common contaminant of potable water supplies, is implicated as an endocrine-disrupting chemical (EDC) and potential carcinogen. Studies show that EDCs can cause irreversible changes in tissue formation, decreased reproductive potential, obesity, and cancer. The U.S. Environmental Protection Agency considers an atrazine concentration of ≤ 3 ppb in drinking water safe for consumption. The specific adverse human health effects associated with a developmental atrazine exposure and the underlying genetic mechanisms of these effects are not well defined. In this study, zebrafish embryos were exposed to a range of atrazine concentrations to establish toxicity. Morphological, transcriptomic, and protein alterations were then assessed at 72 h postfertilization following developmental atrazine exposure at 0, 0.3, 3, or 30 ppb. A significant increase in head length was observed in all three atrazine treatments. Transcriptomic profiles revealed 21, 62, and 64 genes with altered expression in the 0.3, 3, and 30 ppb atrazine treatments, respectively. Altered genes were associated with neuroendocrine and reproductive system development, function, and disease; cell cycle control; and carcinogenesis. There was a significant overlap (42 genes) between the 3 and 30 ppb differentially expressed gene lists, with two of these genes (CYP17A1 and SAMHD1) present in all three atrazine treatments. Increased transcript levels were translated to significant upregulation in protein expression. Overall, this study identifies genetic and molecular targets altered in response to a developmental atrazine exposure to further define the biological pathways and mechanisms of toxicity.
Project description:Incomplete antibiotic removal in pharmaceutical wastewater treatment plants (PWWTPs) could lead to the development and spread of antibiotic-resistant bacteria (ARBs) and genes (ARGs) in the environment, posing a growing public health threat. In this study, two multiantibiotic-resistant bacteria, Ochrobactrum intermedium (N1) and Stenotrophomonas acidaminiphila (N2), were isolated from the sludge of a PWWTP in Guangzhou, China. The N1 strain was highly resistant to ampicillin, cefazolin, chloramphenicol, tetracycline, and norfloxacin, while the N2 strain exhibited high resistance to ampicillin, chloramphenicol, and cefazolin. Whole-genome sequencing revealed that N1 and N2 had genome sizes of 0.52 Mb and 0.37 Mb, respectively, and harbored 33 and 24 ARGs, respectively. The main resistance mechanism in the identified ARGs included efflux pumps, enzymatic degradation, and target bypass, with the N1 strain possessing more multidrug-resistant efflux pumps than the N2 strain (22 vs 12). This also accounts for the broader resistance spectrum of N1 than of N2 in antimicrobial susceptibility tests. Additionally, both genomes contain numerous mobile genetic elements (89 and 21 genes, respectively) and virulence factors (276 and 250 factors, respectively), suggesting their potential for horizontal transfer and pathogenicity. Overall, this research provides insights into the potential risks posed by ARBs in pharmaceutical wastewater and emphasizes the need for further studies on their impact and mitigation strategies.
Project description:The aquatic midge, Chironomus tentans, is a keystone species in aquatic ecosystem and used as a model organism to assess chemicals toxicity in aquatic environment. To characterize midge’s cellular and molecular responses to pesticides, we established cDNA library with 10,000 cDNA elements representing 2,456 C. tentans unique genes. Blast2go identified 49 genes potentially involved in xenobiotics metabolism, including 24 cytochrome p450s (CYPs), 14 esterases (ESTs) and 11 glutathione-s-transferases (GSTs). Based on 2,456 unique genes, a cDNA microarray was developed to monitor gene expression profiles in 4th instar larvae under chlopyrifos (0.1 µg/L and 0.5 µg/L) and 1000 µg/L atrazine 48-hr exposure. We identified 149, 435 and 244 genes were significantly differentially expressed (p-value ≤0.05 with expression ratios ≥2.0) after 0.1 µg/L, 0.5 µg/L chlopyrifos, and 1000 µg/L atrazine application, respectively. Sixteen insect detoxification genes (11 CYPs, 3 GSTs and 2 esterases) were validated by qPCR and their expressions were significantly either up- or down-regulated under chlorpyrifos and atrazine exposure, especially the expression of 10 CYPs were significantly induced after chlopyrifos and atrazine exposure. The up-regulated CYPs might be involved in xenobiotic activation and/or degradation. Furthermore, we also found 5 differentially expressed hemoglobin genes. The expression changes of hemoglobins might be an adaption mechanism of C. tentans to hypoxic condition caused by xenobiotic exposure. This study provides a platform for further functional studies of pesticide-insect interactions in C. tentans.