CELL CYCLE CONTROL IN EARLY DROSOPHILA DEVELOPMENT

在多细胞生物体中，DNA复制的调控是至关重要的 为了他们的发展。此外，对DNA的不当调控 复制可能导致疾病状态，如恶性肿瘤或细胞死亡。 这项建议中的实验解决了发展的两个方面 DNA复制的调控。中最早的控制措施之一 发育是胚胎中DNA复制的重新开始作为回应 为了受精。在大多数生物体中，DNA复制的控制 在一些细胞中发生变化，使S相从 有丝分裂和细胞分裂，导致细胞DNA含量增加 细胞(多年生或多倍体)。这两个方面 DNA复制的发育调节将在 果蝇，黑腹果蝇，因为突变可以在 哪种DNA复制控制不当。 已经鉴定出两个基因，钚(Plu)和盘古(Png)，它们是 在发育初期调节DNA复制。未受精卵 这两个基因中的任何一个的突变都不适当地经历了大量的DNA 复制；此外，所有四种减数分裂产物中的DNA似乎 复制而不是简单地复制原核。PLU和PNG分析 将是理解休眠卵母细胞如何转化为 胚胎发育对成熟和受精信号的响应。 Plu和PNG调控早期DNA复制的机制 这种发展将通过实验来阐明，这些实验将决定 它们控制着进入S阶段，或者是否调控DNA复制 在S阶段，可能是通过阻止重新启动。编码的产品 将通过克隆基因来鉴定plu和png基因，并 他们的蜂窝位置将被确定。发育性表达 的基因，特别是基因产物 在受精后会发生变化。PLU、PNG和PU之间的相互作用 调节发育最早细胞周期的另外四个基因 将通过遗传学和分子方法进行研究。 果蝇的多角化是由于细胞周期的改变，即内切 细胞周期中，S期与间隔期交替，但没有有丝分裂 发生。Endo细胞周期处于发育控制之下，因为 多线化的发生具有精确的时间和空间 胚胎发育后半期的调控。调控基因 在发育过程中触发多线化的开始或控制 将识别和分析Endo细胞周期。侯选人 根据它们的标准，已经分离出了调控基因 在多线化开始时转录激活的几个 胚胎中的组织。这些基因的突变对人类免疫功能的影响 多线化将被确定，而那些被显示为规范的 这一过程将被克隆。将对变种人进行选择 哪个多线化会受到影响。

The regulation of DNA replication in multicellular organisms is critical for their development. In addition, the improper regulation of DNA replication can lead to disease states such as malignancy or cell death. The experiments in this proposal address two aspects of the developmental regulation of DNA replication. One of the earliest controls in development is the restart of DNA replication in the embryo in response to fertilization. In most organisms the control of DNA replication in altered in some of the cells such that S phase becomes unlinked from mitosis and cell division, leading to an increase in the DNA content of the cell (polyteny or polyploidy). These two aspects of the developmental regulation of DNA replication will be investigated in the fruit fly, Drosophila melanogaster, because mutations can be isolated in which DNA replication is improperly controlled. Two genes have been identified, plutonium (plu) and pan gu (png), that regulate DNA replication at the onset of development. Unfertilized eggs mutant in either of these genes inappropriately undergo extensive DNA replication; moreover, the DNA in all four meiotic products appears to replicate rather than simply the pronucleus. Analysis of plu and png will be key to understanding how a resting oocyte is converted into a developing embryo in response to maturation and fertilization signals. The mechanisms by which plu and png regulate DNA replication in early development will be elucidated by experiments that will determine whether they control entry into S phase or whether they regulate DNA replication within S phase, possibly by blocking reinitiation. The products encoded by the plu and png genes will be identified by cloning the genes, and their cellular location will be determined. The developmental expression of the genes will be addressed, particularly whether the gene products are altered after fertilization. The interaction between plu, png, and four other genes that regulate the earliest cell cycles of development will be investigated by genetic and molecular approaches. Polytenization in Drosophila results from a modified cell cycle, the endo cell cycle, in which S phase alternates with a gap phase, but no mitosis occurs. The endo cell cycle is under developmental control because the onset of polytenization occurs with precise temporal and spatial regulation during the latter half of embryogenesis. Regulatory genes that trigger the onset of polytenization in development or that control the endo cell cycle will be identified and analyzed. Candidate regulatory genes have been isolated by the criteria that they are transcriptionally activated at the onset of polytenization in several tissues in the embryo. The effect of mutation of these genes on polytenization will be determined, and those that are shown to regulate this process will be cloned. A selection will be done for mutants in which polytenization is affected.