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:An embryonic atrazine exposure results in reproductive dysfunction in adult zebrafish and morphological alterations in their offspring
Project description:The developmental origins of health and adult disease (DOHaD) hypothesis states that exposure to various environmental stressors early in life can elicit changes to the genome and epigenome thereby resulting in an increased susceptibility of a disease state during adulthood. Atrazine, a common herbicide used throughout the Midwestern United States for control of weeds on various crops frequently contaminates potable water supplies and is a suspected endocrine disrupting chemical. Studies suggest atrazine elicits reproductive dysfunction through the hypothalamus-pituitary-gonadal (HPG) axis. In previous studies, zebrafish were exposed to 0.3, 3, or 30 parts per billion (ppb; ug/L) atrazine through embryogenesis, rinsed, and allowed to mature to adulthood. A decrease in spawning was observed in adults with an embryonic exposure. In addition, adult females had an increase in progesterone and ovarian follicular atresia, alterations in levels of a serotonin metabolite and serotonin turnover in brain tissue, and transcriptome alterations in brain and ovarian tissue supporting neuroendocrine alterations from an embryonic atrazine exposure were reported. Furthermore, offspring of the exposed population exhibited morphological alterations. As reproductive dysfunction may also be influenced by males, this study assessed transcriptomic profiles of brain and testes, morphology, histology, and hormone levels in adult males exposed to atrazine during embryogenesis. Transcriptomic profiles of adult male brain tissue revealed alterations in genes associated with cell to cell signaling and interaction of neurotransmission, cell morphology, cellular assembly and organization of neurites, cellular function and maintenance of neuritogenesis and synaptogenesis, and molecular transport of hormones. In addition, the transcriptomic profiles of adult male testes tissue demonstrated alterations in genes associated with lipid metabolism, molecular transport of steroids, small molecule biochemistry of lipids, and cell morphology. The embryonic atrazine exposure resulted in no alterations in body or testes weight, gonadosomatic index, testes histology, or levels of 11-ketotestosterone or testosterone in adult male zebrafish. Thus, although the transcriptomics data indicate later-in-life alterations on the neuroendocrine system of adult males exposed to atrazine during embryogenesis, analysis of additional endpoints is needed to determine functional impairments. We treated zebrafish embryos from approximately 1 hour post fertilization through 72 hours post fertilization (embryogenesis) to 0, 0.3, 3, or 30 parts per billion (ppb) atrazine. Following the 72 hour exposure period, larave were rinsed and allowed to mature under normal conditions until adulthood (5-6 months post fertilization). At this time, zebrafish were bred weekly for three weeks in order to initiate breeding cycles. Following this peroid, gonadal tissue was disseceted and processed for transcriptomic analysis.
Project description:The developmental origins of health and adult disease (DOHaD) hypothesis states that exposure to various environmental stressors early in life can elicit changes to the genome and epigenome thereby resulting in an increased susceptibility of a disease state during adulthood. Atrazine, a common herbicide used throughout the Midwestern United States for control of weeds on various crops frequently contaminates potable water supplies and is a suspected endocrine disrupting chemical. Studies suggest atrazine elicits reproductive dysfunction through the hypothalamus-pituitary-gonadal (HPG) axis. In previous studies, zebrafish were exposed to 0.3, 3, or 30 parts per billion (ppb; ug/L) atrazine through embryogenesis, rinsed, and allowed to mature to adulthood. A decrease in spawning was observed in adults with an embryonic exposure. In addition, adult females had an increase in progesterone and ovarian follicular atresia, alterations in levels of a serotonin metabolite and serotonin turnover in brain tissue, and transcriptome alterations in brain and ovarian tissue supporting neuroendocrine alterations from an embryonic atrazine exposure were reported. Furthermore, offspring of the exposed population exhibited morphological alterations. As reproductive dysfunction may also be influenced by males, this study assessed transcriptomic profiles of brain and testes, morphology, histology, and hormone levels in adult males exposed to atrazine during embryogenesis. Transcriptomic profiles of adult male brain tissue revealed alterations in genes associated with cell to cell signaling and interaction of neurotransmission, cell morphology, cellular assembly and organization of neurites, cellular function and maintenance of neuritogenesis and synaptogenesis, and molecular transport of hormones. In addition, the transcriptomic profiles of adult male testes tissue demonstrated alterations in genes associated with lipid metabolism, molecular transport of steroids, small molecule biochemistry of lipids, and cell morphology. The embryonic atrazine exposure resulted in no alterations in body or testes weight, gonadosomatic index, testes histology, or levels of 11-ketotestosterone or testosterone in adult male zebrafish. Thus, although the transcriptomics data indicate later-in-life alterations on the neuroendocrine system of adult males exposed to atrazine during embryogenesis, analysis of additional endpoints is needed to determine functional impairments. We treated zebrafish embryos from approximately 1 hour post fertilization through 72 hours post fertilization (embryogenesis) to 0, 0.3, 3, or 30 parts per billion (ppb) atrazine. Following the 72 hour exposure period, larvae were rinsed and allowed to mature under normal conditions until adulthood (5-6 months post fertilization). At this time, zebrafish were bred weekly for three weeks in order to initiate breeding cycles. Following this peroid, gonadal tissue was dissected and processed for transcriptomic analysis.
Project description:The developmental origins of health and adult disease (DOHaD) hypothesis states that exposure to various environmental stressors early in life can elicit changes to the genome and epigenome thereby resulting in an increased susceptibility of a disease state during adulthood. Atrazine, a common herbicide used throughout the Midwestern United States for control of weeds on various crops frequently contaminates potable water supplies and is a suspected endocrine disrupting chemical. Studies suggest atrazine elicits reproductive dysfunction through the hypothalamus-pituitary-gonadal (HPG) axis. In previous studies, zebrafish were exposed to 0.3, 3, or 30 parts per billion (ppb; ug/L) atrazine through embryogenesis, rinsed, and allowed to mature to adulthood. A decrease in spawning was observed in adults with an embryonic exposure. In addition, adult females had an increase in progesterone and ovarian follicular atresia, alterations in levels of a serotonin metabolite and serotonin turnover in brain tissue, and transcriptome alterations in brain and ovarian tissue supporting neuroendocrine alterations from an embryonic atrazine exposure were reported. Furthermore, offspring of the exposed population exhibited morphological alterations. As reproductive dysfunction may also be influenced by males, this study assessed transcriptomic profiles of brain and testes, morphology, histology, and hormone levels in adult males exposed to atrazine during embryogenesis. Transcriptomic profiles of adult male brain tissue revealed alterations in genes associated with cell to cell signaling and interaction of neurotransmission, cell morphology, cellular assembly and organization of neurites, cellular function and maintenance of neuritogenesis and synaptogenesis, and molecular transport of hormones. In addition, the transcriptomic profiles of adult male testes tissue demonstrated alterations in genes associated with lipid metabolism, molecular transport of steroids, small molecule biochemistry of lipids, and cell morphology. The embryonic atrazine exposure resulted in no alterations in body or testes weight, gonadosomatic index, testes histology, or levels of 11-ketotestosterone or testosterone in adult male zebrafish. Thus, although the transcriptomics data indicate later-in-life alterations on the neuroendocrine system of adult males exposed to atrazine during embryogenesis, analysis of additional endpoints is needed to determine functional impairments.