Chromatin and the Control of Late Meiotic Gene Expression

配子发生需要细胞从有丝分裂中退出，并经过修改的细胞分裂程序减数分裂产生分化的配子。从有丝分裂到减数分裂和分化的转变需要细胞中重要的调节回路的重新布线。酵母的孢子形成是一个易于处理的模型系统，可以用来研究这些事件。当酵母细胞完成减数分裂并形成孢子（配子）时，会发生特定的组蛋白修饰，在后生动物的配子发生过程中也有类似的修饰。使用染色质免疫沉淀结合平铺微阵列，这些修饰的组织在染色质中的分布将被定义。此外，通过缺乏修饰的孢子的表型特征和使用显微镜分析来评估野生型和突变型孢子的染色质凝聚，分析了这些变化的功能。产孢后期基因的转录必须在这种染色质改变的情况下进行。染色质和晚期基因表达所需的转录因子之间的相互作用将被探索。

Gametogenesis requires cells to exit from mitosis and undergo the modified cell division program of meiosis to produce differentiated gametes. The shift from mitosis to meiosis and differentiation requires the rewiring of important regulatory circuits in the cell. Sporulation in yeast is a tractable model system in which to study these events. As yeast cells complete meiosis and form spores (gametes) specific histone modifications occur and similar modifications have been reported during gametogenesis in metazoans. Using chromatin immunoprecipitation in combination with tiling microarrays, the distribution of these modified histiones in the chromatin will be defined. Also, the function of these changes with respect to the will be analyzed by phenotypic characterization of spores lacking the modifications and by use of a microscopic assay to assess chromatin condensation in wild-type and mutant spores. Transcription of genes late in sporulation must take place in this altered chromatin context. The interplay between chromatin and a transcription factor necessary for late gene expression will be explored. Meiosis and sporulation occur in response to environmental cues, similar to differentiation in higher cells. Also similar to higher cells, as yeast enter meiosis they pass a commitment point after which, even if the inducing signals are lost or reversed, they nevertheless complete sporulation. As part of this commitment process, the expression of a set of genes important for spore formation becomes insulated from changes in external signals. We will test the hypothesis that these insulated genes represent an autoregulatory gene set and investigate the molecular basis for the insulation of these genes. Whether insulation occurs at the level of transcription or RNA stability will be determined, the cis-acting sequences responsible for insulation will be defined and the protein(s) binding to these seqeunces will be identified.