Sex-Chromosome Genes: Are XY Homologs Allele-Like?

9513537辛普森哺乳动物的性染色体被认为是从一对常染色体进化到半合子状态，但在分子和遗传学时代产生的许多数据并不容易符合这一假设。相对而言，Y染色体只包含很少的基因。然而，一个意想不到的观察是，自性染色体进化以来没有重组的基因被发现与它们的X对应物同源。人们可以通过假设基因具有类似的功能来解释这一观察结果，但鉴于已知的剂量补偿，这是不可接受的。这项研究的长期目标是分析哺乳动物性染色体的功能，特别是Y染色体的Y特异性区域。目前的目标是创造用于Y染色体基因靶向的工具和转基因小鼠品系。将创建具有Y重复的胚胎干细胞系;还将创建与胚胎干细胞系等基因的基因组文库和靶向实验所需的转基因小鼠品系。 我们对性染色体如何在没有过量或不足的性染色体上发现的基因产物的情况下产生两性以及两条染色体上的基因是否在功能上相同的知识非常有限。在分子水平上提出这些问题的必要工具的生产将使我们有可能扩大我们对用于补偿雄性和雌性，特别是哺乳动物染色体数目不平等的机制的理解。 ***

9513537 Simpson Mammalian sex chromosomes are thought to have evolved from an autosomal pair to a hemizygous state but much of the data which have been generated in the molecular and genetic era do not easily fit into that hypothesis. The Y chromosome contains only a few genes, comparatively speaking. However, one unexpected observation has been that genes which had not recombined since the evolution of the sex chromosomes have been found to be homologous to their X counterparts. One could account for this observation by assuming a similar function for the genes but that would not be acceptable in view of what is known of dosage compensation. The long term goal of this research is to analyze the function of the mammalian sex chromosomes, particularly in the Y-specific region of the Y chromosome. The immediate goal is to create the tools and transgenic mouse strains for the purpose of Y chromosome gene targeting. An embryonic stem cell line with a Y duplication will be created; a genomic library isogenic to the embryonic stem cell line and a strain of transgenic mice needed for targeting experiments will also be created. %%% Our knowledge of how the sex chromosomes function to produce the two sexes without either an overdose or underdose of gene products from those genes found on the sex chromosomes and whether the genes on the two chromosomes are functionally identical is very limited. The production of the necessary tools for asking such questions at the molecular level will make it possible to expand our understanding of the mechanisms used to compensate for the inequality of chromosome number in males and females, particularly in mammals. ***