Project description:The present study investigated arsenicâs effects on mummichogs (Fundulus heteroclitus), while also examining what role that gender or age of exposure might play. Adult male and female mummichogs were exposed to 172ppb, 575ppb, or 1,720ppb arsenic as sodium arsenite for 10 days immediately prior to spawning. No differences were noted in the number or viability of eggs between the groups, but there was a significant increase in deformities in the 1,720ppb arsenic exposure group. Total RNA from adult livers or 6-week-old juveniles was used to probe custom macroarrays for changes in gene expression. In females, 3% of the genes were commonly differentially expressed in the 172 and 575ppb exposure groups. In the males, between 1.1-3% of the differentially expressed genes were in common between the exposure groups. Several genes, including apolipoprotein, serum amyloid precursor, lysozyme, and tributyltin-binding protein, were commonly expressed in either a dose-responsive or dose-specific, but across genders, manner. These patterns of regulation were confirmed by QPCR. These findings will provide us with a better understanding of the effects of dose, gender, and exposure age on the response to arsenic. Adult mummichogs (Fundulus heteroclitus) were exposed to either 0 or 172ppb sodium arsenite for 10 days before the full moon. Each treatment group had 5 20-gallon plastic tanks with 2 male and 5 female fish per tank. The fish were exposed via a static renewal, with renewals every 48 hours. Mummichogs were housed at 25C in a 14/10 light/dark cycle at 18% salinity. On the 3 days surrounding the full moon, spawning substrates were provided and eggs collected. Adult males and females: After the last day of egg collection, the adults were euthanized. The livers were removed from the males and females, placed in TRI-ReagentÂ® for RNA isolation (Sigma Chemical Co, St. Louis, MO), and then stored at -80C. Juveniles: Eggs were transferred to clean water and allowed to hatch. The juveniles were grown out in clean water for 6 weeks and then were euthanized. Whole juveniles (7-10 per exposure per tank) were placed in TRI-ReagentÂ® for RNA isolation (Sigma Chemical Co, St. Louis, MO), and then stored at -80C.

Project description:Arsenic (As) exposure is a significant worldwide environmental health concern. Low dose, chronic arsenic exposure has been associated with higher risk of skin, lung, and bladder cancer, as well as cardiovascular disease and diabetes. While arsenic-induced biological changes play a role in disease pathology, little is known about the dynamic cellular changes due to arsenic exposure and withdrawal. In these studies, we seek to understand the molecular mechanisms behind the biological changes induced by chronic low doses of arsenic exposure. We used a comprehensive approach involving chromatin structural studies and mRNA microarray analyses to determine how chromatin structure and gene expression patterns change in response to chronic low dose arsenic exposure and its subsequent withdrawal. Our results show that cells exposed to low doses of sodium arsenite have distinct temporal and coordinated chromatin, gene expression and miRNA changes that are consistent with differentiation and activation of multiple biochemical pathways. Most of these temporal patterns in gene expression are reversed when arsenic was withdrawn. However, some of the gene expression patterns remained altered, plausibly as a result of an adaptive response by these cells. Additionally, these gene expression patterns correlated with changes in chromatin structure, further solidifying the role of chromatin structure in gene regulatory changes due to arsenite exposure. Lastly, we show that arsenite exposure influences gene regulation both at the transcription initiation as well as at the splicing level. Thus our results suggest that general patterns of alternative splicing, as well as expression of particular gene regulators, can be indicative of arsenite-induced cell transformation. A total of eight (8) samples with two biological replicates under four separate conditions: wild-type treated with deionized H2O for 36 days (NT); chronic low-dose arsenic exposure of 1 uM of sodium arsenite (iAs-T) for 36 days; chronic arsenic exposure of 1 uM of sodium arsenite for 26 days followed by removal of sodium arsenite for 10 days, measured at day 36 (iAs-Rev); and chronic arsenic exposure of 1 uM of sodium arsenite for 26 days, followed by removal of sodium arsenite exposure for 10 days, followed by 1 uM of chronic sodium arsenite exposure for 10 days (measured at day 46) (iAs-Rev-T).

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Male Fundulus exposed to 1,720ppb arsenic, and their parentally exposed offspring

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