CONTROL OF CELL TYPE AND GAMETOGENESIS

酿酒酵母的交配型（MAI）基因是一个 细胞类型、细胞形态、细胞周期、细胞周期和细胞周期的遗传和生理控制的复杂网络 谱系和分化。 MAT基因本身的表达 包括通过从沉默拷贝，或供体， 基因座到MAT基因座，其中表达α或α信息。 我们所提出的工作旨在通过以下方式来理解该机制： 哪些MAT基因被转座了 MAT基因的同宗配合转换是 其中α序列的拷贝 在HML或HMR中的信息被用来替换MAT中的信息。 该基因 转化过程由位点特异性内切核酸酶启动，但 链转移的分子机制尚不清楚。 一 这个项目的主要目标是定义发生在 在这个转换过程中， 反应的中间体，并确定MAT和 该过程需要供体基因座。 在这方面，该项目 也试图确定MAT基因的转换在哪些方面是相似的 其他有丝分裂重组事件。 这个项目的第二个主要目标 是了解MAT基因座如何与供体基因座相互作用。 小 是如何将遥远的序列结合在一起的 有效地参与重组事件。 当MATa细胞 开关，它们优先与供体HML相互作用，在左臂上， 相同的染色体，而MATAlpha细胞选择性地与HMR配对。 DNA 将表征与MAT相邻的影响该配对的序列， 影响正常供体偏好的突变也是如此。 细胞进行减数分裂的能力既取决于 MATa和MATAlpha等位基因和生理信号。 实验 还提出了描述22个基因中的一大类突变， 当细胞缺乏氨基酸时，影响正常的G1细胞周期停滞 或者说，他们的成长是一个不平凡的过程。 初步实验表明，这些突变影响了一个 影响蛋白质合成、氨基酸生物合成和 细胞周期停滞

The mating type (MAI) genes of Saccharomyces cerevisiae are part of a complex network of genetic and physiological controls of cell type, cell lineage, and differentiation. The expression of the MAT genes themselves involves their activation by transposition from a silent copy, or donor, locus to the MAT locus, where either a or Alpha information is expressed. The work that we have proposed is designed to understand the mechanism by which MAT genes are transposed. The homothallic switching of MAT genes is a substitution/recombination event in which a copy of a of Alpha sequences at HML or HMR is used to replace the information at MAT. This gene conversion process is initiated by a site-specific endonuclease, but the molecular mechanism by which strands are transferred is not known. One major goal of this project is to define the molecular events occurring during this transposition process, to identify and characterize intermediates of the reaction and to define what DNA sequences at MAT and the donor loci are required for this process. In this regard, the project also seeks to determine in what ways the switching of MAT genes is similar to other mitotic recombination events. A second major goal of this project is to understand how the MAT locus interacts with the donor loci. Little is understood about the ways that distant sequences can be brought together efficiently to participate in a recombination event. When MATa cells switch, they preferentially interact with the donor HML, on the left arm of the same chromosome, while MATAlpha cells selectively pair with HMR. DNA sequences adjacent to MAT that affect this pairing will be characterized, as will mutations that affect the normal donor preference. The ability of cells to undergo meiosis depends both on the presence of MATa and MATAlpha alleles and on physiological signals. Experiments are also proposed to characterize a large class of mutations in 22 genes that affect normal G1 cell cycle arrest when cells are starved for amino acids or grown to stationary phase (and are thus unable to sporulate). Preliminary experiments have suggested that these mutations affect a network of genes that affect protein synthesis, amino acid biosynthesis and cell cycle arrest.