Genome Repatterning Underlying the Co-evolution of Diploid Number and Gender Determination in Turtles

大多数动物的性别是由基因构成决定的（如人类的性别XX/XY染色体，或鸟类的性别ZZ/ZW），而其他动物的性别则由环境温度（TSD）决定，包括海龟。值得注意的是，在性别决定机制中经历过渡的海龟谱系显示染色体数量的进化速度增加了20倍，但尚不清楚为什么或如何将这些特征联系起来。该项目是通过验证染色体重排破坏了位置，从而破坏了控制性发育的基因的调节，从而导致海龟性别决定机制之间的转变，从而阐明这两种特征之间功能联系的第一步。本项目将结合分子细胞遗传学、转录组学、生物信息学和系统发育分析，重建龟祖基因组的组织结构；描述在2.1亿年的海龟进化过程中发生的海龟染色体重排；并对海龟性别决定机制转变背后的性发育调控网络中的关键要素建立机制假设，以供进一步研究。本项目提出了一个关于长时间基因组进化与性别决定关系的新假设，如果这一假设成立，将改变我们对性别决定进化机制的理解。更广泛的影响本项目的教育活动将通过培训学生和他们的导师，帮助整合以发现为基础的本科学习，并扩大未被充分代表的群体对生物学的参与；通过外联活动吸引妇女和少数群体参与；并加强PI作为代表性不足群体的榜样的资格。

Gender is determined by genetic constitution in most animals (as by sex XX/XY chromosomes in humans, or ZZ/ZW in birds), and by environmental temperature (TSD) in others, including turtles. Notably, turtle lineages that underwent a transition in the gender-determining mechanism show a 20-fold increase in the rate of evolution of chromosome number, but it is unclear why or how these traits are associated. This project represents the first step to elucidate the functional link between these two traits by testing the hypothesis that chromosomal rearrangements disrupt the location and consequently the regulation of genes controlling sexual development, which in turn cause the transition between gender-determining mechanisms among turtles. By combining molecular cytogenetics, transcriptomics, bioinformatics and phylogenetic analyses, this project will reconstruct the organization of the ancestral turtle genome; characterize the chromosomal rearrangements that have taken place among turtles over 210 million years of turtle evolution; and build mechanistic hypotheses about the critical elements in the regulatory network of sexual development that underlie transitions in gender-determining mechanisms in turtles for further study. This project proposes a novel hypothesis about the relationship of genome evolution over large spans of time and gender determination, which if true, could transform our understanding of the mechanism by which gender determination evolves.Broader ImpactsThe educational activities of this project will help integrate undergraduate discovery-based learning and broaden the participation of underrepresented groups in biology by training students and their mentors; by engaging women and minorities through outreach activities; and by strengthening the PI's qualifications as role model for underrepresented groups.