Adult and Transgenerational Toxicity Due to Developmental TCDD Exposure

描述（由申请人提供）：改善人类健康的一个重要目标是了解妊娠期和儿童期接触环境毒物如何导致成年后的疾病。确定一次早期接触有毒物质是否会影响后代的健康也至关重要。了解和识别这些风险将对人类健康产生积极影响。我的研究重点是用斑马鱼来了解在发育过程中暴露于万亿分之一（ppt）水平的2,3,7,8四氯二苯并对二恶英（TCDD，二恶英）的成年人的两种毒性反应。我们发表的工作和我的初步结果表明，在发育过程中，单次暴露会导致成年动物骨骼畸形和生殖毒性，并在随后的F1和F2代中产生各种形式的毒性。成年毒性包括明显的雄性雌性化，其中具有雌性第二性征的鱼有睾丸。目的是确定TCDD是否会改变性腺命运，将卵巢变为睾丸，或使男性的身体女性化。另一个主要的中毒迹象是

DESCRIPTION (provided by applicant): An important goal in improving human health is to understand how exposure to environmental toxicants during gestation and childhood leads to disease later in adulthood. It is also vital to determine whether a single early toxicant exposure can affect the health of subsequent generations. Understanding and identifying these risks will positively impact human health. My research focus is to use zebrafish to understand two toxic responses seen in adults exposed during development to 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD, dioxin), at the parts per trillion (ppt) level. Our published work and my preliminary results indicate that a single exposure during development can cause skeletal malformation and reproductive toxicity in the adults, and various forms of toxicity in the subsequent F1 and F2 generations. F0 adult toxicity includes an apparent male feminization in which fish with female secondary sex characteristics have testes. A goal is to determine whether TCDD alters gonadal fate, changing ovaries to testes, or feminizes the body of males. Another major sign of toxicity in adults exposed during early development is malformations in the axial skeleton resembling human scoliosis. I will identify the source of these changes in skeletal development examining bone and collagen by staining and measuring alterations in gene expression. Down-regulation of the sox9b gene is the cause of TCDD-induced jaw malformation in zebrafish. The human sox9 gene is a master regulator of both skeletal formation and sex specification: sox9 is thought to be the target of the male Y-chromosome sry gene. I have also observed sox9b expression at the site of vertebral development in zebrafish. Therefore, I will examine the expression of both zebrafish homologs of human sox9: sox9a and sox9b in developing bone and gonad of TCDD-treated zebrafish. I find reproducible toxicity in F1 and F2 offspring of F0 fish that were exposed only briefly during development. I will better characterize this transgenerational toxicity, measuring changes in global gene expression in affected tissues from each generation and will use both gene- specific and global techniques to examine alterations in DNA methylation and chromatin structure induced by TCDD exposure and transmitted into F1 and F2 fish. In year 3 of this project, I plan to use the results from this work as preliminary data to apply for an R21 or R03 grant. Transgenerational work, even in zebrafish, takes several years to mature, so the proposed work would allow a future grant to focus on mechanisms driving my results. As a K01 recipient, I will follow a career development plan with very specific research and development milestones for each award year. I will meet regularly with my mentors and advisory committee to strengthen my ability to link translational and mechanistic research. I will obtain experiential training in areas needed for a successful career in translational research, including project planning, manuscript and grant writing, and identification and mastery of cellular and molecular techniques needed to move my research forward. I have a clinical background with a research emphasis. I will gain experience in mechanistic, hypothesis testing driven research. This plan will stretch my research expertise and enhance my training in developmental toxicology research. The University of Wisconsin has numerous NIH-sponsored training programs, core facilities and funded researchers making it an ideal training environment for me to develop as an independent scientist.