Chromatin and the Control of Late Meiotic Gene Expression

配子发生需要细胞退出有丝分裂，并经历减数分裂的改良细胞分裂程序，以产生分化的配子。从有丝分裂到减数分裂和分化的转变需要重新连接细胞中重要的调节电路。酵母菌中的孢子形成是研究这些事件的一个易于处理的模型系统。随着酵母细胞完成减数分裂并形成孢子(配子)，特定的组蛋白修饰发生，在后生动物配子发生过程中也有类似的修饰被报道。使用染色质免疫沉淀与平铺微阵列相结合，将确定这些修饰组氨酸在染色质中的分布。此外，通过缺乏修饰的孢子的表型特征以及使用显微镜方法评估野生型和突变型孢子的染色质凝聚，来分析这些变化对染色体的作用。孢子形成后期基因的转录必须发生在这种改变的染色质环境中。染色质和晚期基因表达所必需的转录因子之间的相互作用将被探索。 减数分裂和产孢子发生在对环境信号的反应中，类似于高等细胞的分化。 同样与高等细胞类似，当酵母进入减数分裂时，它们会通过一个承诺点，在此之后，即使诱导信号丢失或逆转，它们仍能完成产孢子。作为这一承诺过程的一部分，一组对孢子形成至关重要的基因的表达不受外部信号变化的影响。我们将检验这样一种假设，即这些被隔离的基因代表一个自我调节的基因集，并研究这些基因被隔离的分子基础。将确定绝缘是否发生在转录水平或RNA稳定性，负责绝缘的顺式作用序列将被定义，并将确定与这些序列结合的蛋白质(S)。

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.