Molecular Analysis of Chlamydomonas Mating-Type Locus

本项目的长期目标是分析莱茵衣藻（Chlamydomonas reinhardtii）性别分化的遗传控制。生物体在其生命周期中分化为4种不同的细胞类型，这些程序中的大多数（如果不是全部的话）是由其交配型（mt）位点控制的，该位点以一对表观等位基因的形式存在。遗传mt+基因座的细胞在氮饥饿条件下分化为正配子，只能与互补的负等位基因进行交配相互作用和合子形成。本提案的具体目标是：1。确定中基因的基因产物是否在配子发生过程中负责指导mt-性别分化，并确定它是否直接或与其他蛋白质协同作用，在此期间引发负特异性结构基因的转录。2. 目的：确定一株莱茵梭菌中基因和约20kb侧链DNA向常染色体位置移动的机制。将做进一步的工作，以确定当常染色体交叉到正背景时该元素丢失的原因。3. 该基因的同源物已在一种近亲——赤蝽中被鉴定出来，并将进行实验以确定其染色体位置和构型的相似性或差异性。其他更远的亲缘物种将被筛选保护的中间基因区域。莱茵瓢虫的中间位点被认为是配子体发生过程中负责指导雌雄分化的基因，将对其功能进行研究。该基因的染色体位置的影响也将通过与密切相关的衣藻物种进行比较来研究，其中该基因位于非性染色体上。基因的保存水平将通过筛选更遥远的物种来确定。这些研究应该加强我们对“早期”真核生物的一个重要代表是如何决定性别分化的理解。＊＊＊

9513919 Goodenough The long range goal of this project is to analyze the genetic control of sexual differentiation in the unicellular green alga Chlamydomonas reinhardtii. The organism differentiates into 4 distinct cell types during the course of its life cycle and most, if not all, of these programs are governed by its mating-type (mt) locus which exists as a pair of apparent alleles. Cells inheriting the mt+ locus differentiate as plus gametes in response to nitrogen starvation and are capable of mating interactions and zygote formation only with complementary minus alleles. The specific goals of this proposal are: 1. To determine if the gene product of the mid gene is responsible for directing mt- sexual differentiation during gametogenesis and to determine if it acts directly or in concert with other proteins to elicit the transcription of minus- specific structural genes during that period. 2. To define the mechanisms responsible for the movement of the mid gene and about 20 kb of flanking DNA to an autosomal location in a specific strain of C. reinhardtii. Further work will be done to determine the cause for the loss of the element when the autosome is crossed into a plus background. 3. A homologue of the mid gene has been identified in C. incerta, a close relative and experiments will be done to determine similarities or differences in chromosomal location and or configurations. Other more distantly related species will be screened for conservation of the domains of the mid gene. %%% The mid locus of C. reinhardtii has been characterized as the gene responsible for directing mt- sexual differentiation during gametogenesis will be studied in respect to its function. The effect of chromosomal position of the gene will also be studied by comparison with a closely related species of Chlamydomonas where the gene is located on an non-sex chromosome. The level of conservation of the gene will be determined by screening of more distantly related species. These studies should enhance o ur understanding of how sexual differentiation is determined in an important representative of the "early" eukaryotes. ***