CAREER: Evolution of allosomes and dosage compensation in terrestrial isopods

异染色体是决定性别的染色体，就像哺乳动物的X和Y染色体一样，它们在物种进化生物学中起着至关重要的作用。它们在许多物种中独立进化，虽然这些染色体在不同的群体中有许多相似之处，但它们也表现出重要的差异。然而，解释这些差异仍然很困难。虽然大量的理论工作对异体体的进化做出了几个重要的预测，但最终测试这些预测一直很困难，因为大多数先前的研究都集中在一小部分模式生物上。本项目将通过检查陆生等足类甲壳动物（包括木虱和药虫）中的异体体来解决这个问题。陆生等足类动物是这些问题的理想群体，因为它们在性别决定机制上表现出相当大的差异，但令人惊讶的是，它们的基因组很少受到关注。拟议的实验旨在帮助解释为什么这些染色体如此独特，以及它们如何有助于重要的生物过程。重要的是，该项目还将促进科学的多样性，并为学生创造实践教育机会，特别是吸引那些来自服务不足群体的学生。首先，将开发一个基于项目的基因组学课程，并公开提供课程材料。第二，将建立一个国际暑期项目，为纽约州立大学奥斯韦戈的本科生提供到国外进行研究的机会。最后，这项工作将通过让参加现有科学和数学夏季“桥梁”夏令营的新生参加跨学科的实验室活动来激发校园研究的兴趣。该项目将解决三种陆生等足类甲壳动物（Trachelipus rathkei，Porcellio laevis和Armadillidium vulgare）的异体体进化的关键问题。 这项研究将（i）确定性别决定染色体的变化发生在等足类动物进化树上;（ii）测试这些染色体上的基因是否比常染色体基因受到自然选择和遗传漂变的影响更强烈;（iii）测试这些物种是否表现出剂量补偿。 使用全基因组测序和通过RNA测序的基因注释的比较方法将用于解决前两个目标。荧光原位杂交（FISH）也将用于确定物种间的同种异体同源性。陆生等足类动物的性别可以通过手术切除或植入雄激素腺来实验性地操纵，这提供了一个独特的机会，可以在相同和异性的操纵和未操纵个体中使用RNA测序来准确地测试剂量补偿。 通过研究一个独特的分类组，这项研究将有助于研究早期关于异体的工作所提出的模式的一般性，为许多生物体基因组（包括人类基因组）的这些有影响力的组成部分提供重要的见解。

Allosomes are chromosomes that determine sex, like the X and Y chromosomes in mammals, and they play crucial roles in the evolutionary biology of species. They have evolved independently in a wide array of species, and while these chromosomes in different groups share many similarities, they also exhibit important differences. Explaining these differences, however, remains difficult. While a strong body of theoretical work makes several important predictions regarding the evolution of allosomes, conclusively testing those predictions has been difficult because most prior research has focused on a small subset of model organisms. This project will address this problem by examining allosomes in terrestrial isopod crustaceans, which include woodlice and pillbugs. Terrestrial isopods are an ideal group for these questions because they exhibit considerable variation in sex-determining mechanisms, but, surprisingly, their genomes have received little attention. The proposed experiments are designed to help explain why these chromosomes are so unique, and how they contribute to vital biological processes. Importantly, this project will also promote diversity in science and create hands-on educational opportunities for students, especially engaging those from under-served groups. First, a project-based genomics course will be developed, and course materials made publicly available. Second, an international summer program will be established that provides undergraduates at SUNY Oswego with opportunities to conduct research abroad. Finally, this work will generate interest in research on campus by allowing incoming freshmen participating in an existing science and math summer 'bridge' camp to take part in interdisciplinary laboratory activities.This project will address key questions on the evolution of allosomes in three species of terrestrial isopod crustaceans (Trachelipus rathkei, Porcellio laevis, and Armadillidium vulgare). This research will (i) identify where changes in sex-determining chromosomes have occurred on the isopod evolutionary tree; (ii) test whether genes on these chromosomes are affected more strongly than autosomal genes by natural selection and genetic drift; and (iii) test whether these species exhibit dosage compensation. A comparative approach using whole genome sequencing and gene annotation via RNA sequencing will be used to address the first two aims. Fluorescent in-situ hybridization (FISH) will also be used to determine homology of allosomes among species. The sex of terrestrial isopods can be experimentally manipulated through surgical ablation or implantation of androgenic glands, which offers a unique opportunity to accurately test for dosage compensation using RNA sequencing in manipulated and unmanipulated individuals of the same and opposite sex. By studying a unique taxonomic group, this research will help examine the generality of patterns suggested by earlier work on allosomes, providing significant insights into these influential components of so many organisms' genomes, including those of humans.