Mechanisms of vertebrate post-embryonic developmental progression

描述（由申请人提供）：我们仍然对脊椎动物发育后期调节和同步形态发生事件的机制知之甚少。尽管如此，了解控制这些后期发育时期的因素对于了解成人特征如何形成至关重要，并将有助于深入了解人类胚胎后胎儿和新生儿时期出现的形态缺陷和疾病。这项研究利用了斑马鱼，它经历了广泛的胚胎后发育，涉及许多不同器官系统的修饰和成熟;其中许多变化与人类胚胎发生后发生的过程相似或相同。该建议采用了几种策略，以了解斑马鱼从幼虫到幼鱼转化的机制。第一个目标采用有针对性的方法，测试甲状腺激素在胚胎后发育过渡中的特定作用。多种证据表明甲状腺激素参与斑马鱼的几个发育过程，但这种激素影响特定形态发生过程和细胞行为的能力仍不清楚。这一目标将测试甲状腺激素在促进整体体细胞发育进程和特定的，充分表征的细胞谱系，产生成人色素沉着在幼虫到少年过渡的行为中的作用。第二个目标是采取前瞻性遗传策略，以确定胚胎后阶段过渡所需的新基因。这种方法已经确定了两个突变体，表现出完全体细胞停滞在幼虫发育，停止个体发育的阶段通常达到2和3周龄的野生型幼虫。这些表型表明胚胎后进展绝对需要的基因受损。映射和克隆的突变和表征的途径，它们属于将揭示胚胎后发育过程中必不可少的机制，继续这种屏幕将确定进一步的幼虫逮捕表型。最终的目的是利用与斑马鱼相关的物种，该物种表现出自然的失败，无法执行体细胞胚胎后发育的终末阶段。主要集中在皮肤内的结构和表达，遗传和发育结构的变化将在胚胎后发育截断的背景下阐明。这些分析将揭示性状和调控途径之间的解耦程度，以及休眠遗传途径是否对胚胎后发育的关键内分泌介质保持反应性。总体而言，这些努力将表征已知的内分泌调节因子的形态发生作用，将确定调节正常胚胎后进展的新因素，并将建立一个新的模型，用于解剖发育遗传途径和内分泌机制的演变方式。此外，该项目将完成一位具有种群生态学背景的学者的发育生物学和遗传学培训，并将为她的独立研究实验室奠定基础。

DESCRIPTION (provided by applicant): We still know very little about the mechanisms that regulate and synchronize morphogenetic events during later stages of vertebrate development. Nonetheless, understanding the factors controlling these later developmental periods is essential to understanding how adult traits form, and will lend insight into morphological defects and disorders that arise during human post-embryonic fetal and neonatal periods. This research utilizes the zebrafish, which undergoes extensive post-embryonic development involving modifications and maturation in many different organ systems; many of these changes are similar or identical to processes that occur following embryogenesis in humans. This proposal employs several strategies towards understanding the mechanisms underlying the zebrafish transformation from larva to juvenile. The first aim adopts a targeted approach, testing the specific roles of thyroid hormone in post-embryonic developmental transitions. Multiple lines of evidence indicate that thyroid hormone is involved in several developmental processes in zebrafish, but the ability of this hormone to effect specific morphogenetic processes and cellular behaviors remains unclear. This aim will test roles of thyroid hormone in promoting both global somatic developmental progression and the behaviors of a specific, well-characterized cell lineage that produces adult pigmentation during the larval-to-juvenile transition. The second aim takes a forward genetic strategy to identify novel genes required for post-embryonic stage transitions. This approach has already identified two mutants that exhibit complete somatic arrest during larval development, ceasing ontogenetic progression at stages normally reached by 2- and 3-week old wild-type larvae. These phenotypes suggest an impairment of genes absolutely required for post-embryonic progression. Mapping and cloning the mutations and characterizing the pathways to which they belong will reveal mechanisms essential for post-embryonic developmental processes; continuation of this screen will identify further larval arrest phenotypes. The final aim utilizes a species related to zebrafish that exhibits a natural failure t execute the terminal stages of somatic post-embryonic development. Focusing primarily on the structure and expression within the skin, changes in genetic and developmental architecture will be elucidated in this context of post-embryonic developmental truncation. These analyses will reveal the both extent of decoupling between traits and regulatory pathways, and whether dormant genetic pathways retain responsiveness to a key endocrine mediator of post-embryonic development. Overall, these efforts will characterize the morphogenetic roles of a known endocrine regulator, will identify novel factors that regulate normal post-embryonic progression, and will establish a novel model for dissecting the ways in which developmental genetic pathways and endocrine mechanisms can evolve. Moreover, this project will complete the developmental biology and genetics training of a scholar with a background in population ecology, and will establish the foundation for her independent research laboratory.