B Mating-Type Specificities and Pheromones in Schizophyllum

9513513 Raper：这项研究的目的是了解一个简单的真核生物如何在调节交配和发育方面区别于许多非自我。其具体目的是阐明多个B交配型基因在蘑菇中触发有性发育的机制。B基因位于两个连锁的基因座上，即B(和B()，在世界范围内的人群中，每个基因都有九个不同的版本或特性。交配配对必须在B(或B()上不同，才能相容：36个可能的配对中的任何一个在任何一个座位上具有不同的特异性，都会导致启动相同的发育途径。这种情况是如何发生的？最近对每个基因座的一种特异性的分析，L和B(1)发现了信息素和信息素受体的基因，与在其他真菌中发现的基因相似。然而，所有之前描述的真菌系统只有两个不同版本的这种基因。在S.公社，有多种版本。一个解释公社多个B交配类型的模型是，每个座位上的每个专一性都由信息素和信息素受体基因的唯一组合定义。这些基因共同进化，以确保单一特异性的B交配型基因座内的任何基因组合都不能编码一对能够激活自身性发育的分子；只有由该基因座的不同特异性编码的分子才能相互作用来激活这条途径。我们认为，多个B交配型的基础是由多种信息素和信息素受体组成的独特系统，这些信息素和信息素受体是性形态发生的主要调节因素。该项目的重点是通过定义B(3和B(2)基因座的功能遗传成分并将其与B(L和B(1)基因座的基因进行比较来检验这一模型，这两个基因座目前正在与两个欧洲实验室合作研究。野生型B(3和B(2)基因座的基因也将与这些基因座中的一系列现有突变基因进行比较，这些基因座导致各种表型缺陷。这些比较将开始解释功能的特异性是如何由每个基因座的基因决定的，以及为什么这些基因的某些配对激活发育，而其他配对不激活。研究分为三个部分：1)通过比较定义B(3和B(2)与B(L和B(1.2))的遗传元件之间的异同，确定野生型等位基因功能特异性的基础。通过在B(2)基因座内定义破坏这一功能的突变，了解B交配型基因如何决定自我/非我识别的特异性。3)通过将一系列突变与表型变化相关联，确定B(2)基因座内多个基因的特定功能。还定义了突变体内的预测缺失，以便在转化实验中用作受体，以测试野生型和突变的B交配型基因的各种组合的效果。将检查选定的B交配型基因的表达模式，以寻找与发育有关的调控证据。这项研究将通过使用标准的DNA克隆、测序、序列分析、核酸杂交、PCR扩增和DNA介导的转化等技术来完成。这项研究的长期目标是了解在发育简单的多细胞真核生物过程中，多种信息素和信息素受体是如何调节交配和细胞间通讯的。正在研究的生物是木生担子菌Schlzophyllum公社。这种真菌，像它的其他种类一样，有数千种交配类型。这位研究人员认为，单倍体个体在调节性发育方面能够将自己与许多非自我区分开来的潜在机制，对于理解真核生物中的多细胞发育是基本相关的。S.Comme是这项研究的理想模型系统，因为它可以在实验室中相对容易地操作，并且可以为分子遗传学研究提供大量的背景信息。***

9513513 Raper The aim of this research is to understand how a simple eukaryote distinguishes itself from many nonselves in regulating mating and development. The specific objective is to clarify the mechanism by which the multiple B mating-type genes trigger sexual development in the mushroom Schizophyllum commune. The B genes are in two linked loci, B( and B(, each of which has nine different versions, or specificities, in the world-wide population. A mating pair must be different at either B( or B( to be compatible: any of the 36 possible pairings of different specificities at either locus results in initiation of the identical developmental pathway. How does this occur? Recent analysis of one specificity at each locus, B(l and B(1, has revealed genes for pheromones and pheromone receptors similar to those found in other fungi. All previously described fungal systems, however, have only two different versions of such genes. In S. commune, there are multiple versions. A model to explain multiple B mating types in S. commune is that each specificity at each locus is defined by a unique combination of pheromone and pheromone receptor genes. These genes have coevolved so as to insure that no combination of genes contained within the B mating-type locus of a single specificity encodes a pair of molecules capable of activating sexual development in self; only molecules encoded by different specificities of that locus can interact to activate the pathway. It is proposed that the basis for multiple B mating-types in S. commune is a unique system of multiple pheromone and pheromone receptors which act as master regulators of sexual morphogenesis. The focus of this project is to test this model by defining the functional genetic components of the B(3 and B(2 loci and comparing these with the genes of the B(l and B(1 loci which are currently being studied in collaboration with two European laboratories. Genes of the wild-type B(3 and B(2 loci will also be compared to a series of existing mutated genes within these loci that cause a variety of defective phenotypes. These comparisons will begin to explain how specificity of function is determined by the genes of each locus, and why certain pairings of these genes activate development while others do not. The research is divided into three parts: 1) Determine the basis for specificity of function among wild-type alleles by comparing differences and similarities between genetic elements that define B(3 and B(2 versus B(l and B(1. 2) Gain understanding of how the B mating-type genes determine specificity for self/nonself recognition by defining a mutation within the B(2 locus that destroys this function. 3) Determine specific functions of the multiple genes within the B(2 locus by correlating a series of mutations with changes in phenotype. Also define predicted deletions within the mutants for use as recipients in transformation experiments in order to test the effect of various combinat1ons of wild-type and mutated B mating-type genes. The pattern of expression of selected B mating-type genes will be examined for evidence of regulation with respect to development. This research will be accomplished by using standard techniques of DNA cloning, sequencing, sequence analysis, nucleic acid hybridization, PCR amplification, and DNA-mediated transformation of S. commune. %%% The long-term goal of this research is an understanding of how multiple pheromones and pheromone receptors regulate mating and cell-to-cell communication during development simple multicellular eukaryote. The organism being studied is the woodrotting Basidiomycete Schlzophyllum commune. This fungus, like other members of its class, has thousands of mating types. The investigator believes that the underlying mechanisms by which a haploid individual can distinguish self from many nonselves in regulating sexual development is fundamental relevance to an understanding of multicellular development in eukaryotes generally. S.commune is an ideal model system for this study because of the relative ease with which it can be manipulated in the laboratory and the substantial background information available for molecular genetic studies. ***