A mechanistic approach to understand the tissue-specific development of toxicity in response totransgenerational chronic arsenic exposures - Title: A mechanistic approach to understand the tissue-specific development of toxicity in response to transgenerational chronic arsenic exposures Abstract: Arsenic compounds are common environmental toxicants associated with numerous adverse health effects in humans. Several genetic, molecular and cellular processes have been implicated in the complex etiology of arsenic toxicity, although the precise mode of action is not fully understood. Maternal exposure to chronic arsenic at concentrations below U.S. Environmental Protection Agency’s recommended maximum of 10 μg/L has been related to several birth and developmental defects indicating a transgenerational impact in toxicity development. Maternal chronic exposures also lead to preferential accumulation of arsenic in certain tissues making them more vulnerable to toxicity effects compared to the rest. However, the relationship between transgenerational exposure, localized arsenic accumulation and subsequent toxicity impacts are unknown. Previously, we showed exposure to chronic arsenic concentrations over 10 generations increased resilience to high arsenic levels and decreased growth and reproduction in our model organism Daphnia, indicating the presence of a significant maternal influence in long-term arsenic toxicity development. Additionally, we identified gene pathways and metabolic proteins that showed differential expression in response to transgenerational arsenic exposure in Daphnia. In this application, we build on these results to identify tissue specific sub-cellular processes that regulate long-term phenotypic indicators in animals for a more mechanistic understanding of arsenic toxicity. The overarching goal is to establish functional links between gene expression and associated phenotypic manifestations in response to long-term arsenic exposure in Daphnia to identify tissue-specific biomarkers for a more efficient assessment of individual susceptibilities. We hypothesize that transgenerational susceptibilities to maternal exposure will be mediated by both tissue-specific (unique) as well as common metabolic and cellular processes in Daphnia. Specifically, we aim to – (1) Detect tissue-specific uptake of arsenic in response to transgenerational chronic exposure using techniques in laser-ablation-ICP-MS; (2) Identify tissue-specific gene expression levels in response to transgenerational arsenic exposure using techniques in RNA sequencing and comparative genomics; and (3) Detect conserved genetic biomarkers of arsenic toxicity in mammalian cells using techniques in qPCR. Identifying evolutionary conserved genetic processes regulating toxicity responses to environmentally relevant chronic concentrations will advance our understanding on the mode of action of not only Arsenic but other common environmental toxicants, potentially leading to effective mitigation strategies in vulnerable human populations as incidences of Arsenic continues to rise across the world.
