Molecular Analysis of Chlamydomonas Mating-Type Locus

单细胞绿藻莱茵衣藻在其生命周期中分化为4种不同的细胞类型。这些分化程序大部分（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（mt+和mt-）的形式存在。染色体漫步记录了mt位点包括高度重排的部分，这使得mt+和mt-彼此非常不同。与真菌交配型基因座类似，这种重排结构域可能包括控制生命周期转变的基因。一个这样的基因已经在该区域被发现：赋予mt+配子与mt-配子融合能力的imp-1基因，由于其在imp-1突变体中的破坏，已经定位在重排结构域的一个片段上。来自重排结构域的其他序列将用于鉴定额外的mt连锁基因，鉴定来自细胞类型特异性，mt连锁基因的cDNA克隆，以及鉴定其产物调节配子细胞交配表型的基因。这一分析将增强我们对真核生物基因调控和细胞分化的进化的理解。

The unicellular green alga Chlamydomonas reinhardtii differentiates into 4 distinct cell types during the course of its life cycle. Most if not all of these differentiation programs are governed by its mating-type (mt) locus which exists as a pair of apparent alleles (mt+ and mt-). A chromosome walk has documented that the mt loci include highly rearranged sectors which render mt+ and mt- very dissimilar to one another. By analogy with fungal mating-type loci this rearranged domain may include genes that govern life-cycle transitions. One such gene has already been identified in the region: the imp-1 gene, which confers upon mt+ gametes the ability to fuse with mt- gametes, has been localized to a segment of the rearranged domain by virtue of its disruption in imp-1 mutants. Additional sequences from the rearranged domains will be used to identify additional mt-linked genes, to identify cDNA clones derived from cell-type-specific, mt-linked genes, and to identify genes whose products regulate the mating phenotype of gametic cells. %%% This analysis should enhance our understanding of the evolution of eukaryotic gene regulation and cell differentiation.