GENETIC ANALYSIS OF CELL DIVISION PATTERN IN MAIZE

玉米细胞分裂模式的遗传分析

• 批准号: 2192417
• 负责人: LAURIE G SMITH
• 金额: $ 7.43万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-09-01 至 2000-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2192417
• 关键词: GENETIC; ANALYSIS; CELL; DIVISION; PATTERN

The spatial control of cytokinesis is an important aspect of development in multicellular organisms. Division plane positioning is not only critical for the proper segregation of chromosomes and organelles to daughter cells, but can also influence the developmental fates of the daughter cells. The spatial control of cytokinesis is of particular significance in plant development, where cells are embedded in a rigid extracellular matrix, the cell wall: the relative positions of cells within plant tissues are fixed at birth by planes of cell division. Although the processes of division plane determination and cytokinesis are in some respects different in animals and plants, in both cases they involve cytoskeleton-mediated interactions between the nucleus/microtubule organizing centers and the cell cortex that position the cytokinetic apparatus appropriately within the dividing cell. The molecular mechanisms underlying these interactions are poorly understood in both animals and plants, and are currently being studied by means of biochemical and genetic methods. The project described in this proposal represents a genetic approach to understanding the spatial control of cytokinesis in a higher plant, Zea mays. Because of the lack of relative cell movement in plant tissues, mutants with alterations in cell division pattern can be recognized by means of the resulting alterations in the regular cell pattern of the mature maize leaf. The proposal concentrates on the analysis of a gene required for the spatial control of cytokinesis that was identified in this way, Tangled (Tan). More specifically, the phenotype of this mutant indicates that the Tan gene is required for elongated cells to divide in a plane parallel to the cell's long axis. Specific Aim l is to develop a better understanding of the function of this gene by investigating the cellular basis of the tan mutant defect. This will be accomplished by means of comparisons between mutant and wild-type leaves with respect to: 1) cytoskeletal rearrangements m dividing cells, 2) aspects of cell division that can be observed in living tissues by video microscopy, and 3) divisions in various tissues throughout the plant involving cells of different shapes. The tan mutation was caused by the insertion of a transposable element; fragments of the Tan gene adjacent to the transposon insertion site have already been cloned. Specific Aim 2 is to complete the cloning of the Tan gene, analyze the predicted amino acid sequence of its product for homology to other proteins, and examine the tissue and subcellular localization of this protein to try to understand at a molecular level its involvement in spatial aspects of cytokinesis. Specific Aim 3 is to use genetic mosaic analysis to determine whether the Tan gene functions cell autonomously, and to explore the role of cell-cell interactions in the control of cell division pattern in plant tissues. Finally (Specific Aim 4), further screening for recessive mutations altering the cell pattern of the maize leaf will be done to identify other genes required for the spatial control of cell division in plants. Insights gained from these studies will contribute to our understanding of mechanisms regulating cell division in eukaryotic organisms that are essential for normal development, and the loss of which is associated with neoplastic diseases in humans and animals.

胞质分裂的空间控制是发育的一个重要方面 在多细胞生物中。划分平面定位不仅 对于染色体和细胞器的正确分离至关重要 子细胞，但也可以影响子细胞的发育命运 子细胞。胞质分裂的空间控制具有特殊性 在植物发育中具有重要意义，其中细胞被嵌入刚性的 细胞外基质、细胞壁：细胞的相对位置 植物组织内的细胞在出生时就被细胞分裂平面所固定。 尽管划分平面确定和胞质分裂的过程 动物和植物在某些方面是不同的，在这两种情况下 涉及细胞骨架介导的相互作用 细胞核/微管组织中心和定位的细胞皮层 细胞分裂器适当地位于分裂细胞内。这 这些相互作用背后的分子机制尚不清楚 在动物和植物中，目前正在通过以下方式进行研究 生物化学和遗传学方法。本提案中描述的项目 代表了理解空间控制的遗传方法 高等植物玉米的胞质分裂。因为缺乏亲人 植物组织中的细胞运动，细胞分裂发生改变的突变体 模式可以通过所产生的变化来识别 成熟玉米叶的规则细胞模式。该提案集中 胞质分裂空间控制所需基因的分析 就是这样识别的，Tangled（Tan）。更具体地说， 该突变体的表型表明 Tan 基因是 细长的细胞在平行于细胞长轴的平面上分裂。 具体目标是更好地理解 通过研究 tan 突变缺陷的细胞基础来研究该基因。 这将通过突变体和突变体之间的比较来完成 野生型叶在以下方面： 1) 细胞骨架重排 m 分裂细胞，2) 可以观察到的细胞分裂的各个方面 通过视频显微镜观察活体组织，以及 3) 各种组织的分裂 整个植物涉及不同形状的细胞。晒黑的 突变是由转座元件的插入引起的；碎片 与转座子插入位点相邻的 Tan 基因已经 被克隆了。具体目标2是完成Tan基因的克隆， 分析其产物的预测氨基酸序列的同源性 其他蛋白质，并检查其组织和亚细胞定位 这种蛋白质试图在分子水平上理解它的参与 在胞质分裂的空间方面。具体目标 3 是利用遗传 镶嵌分析以确定 Tan 基因是否具有细胞功能 自主地，并探索细胞与细胞相互作用在 植物组织中细胞分裂模式的控制。最后（具体目标 4)、进一步筛选改变细胞模式的隐性突变 将完成玉米叶的鉴定，以确定该基因所需的其他基因 植物细胞分裂的空间控制。从这些内容中获得的见解 研究将有助于我们理解调节机制 真核生物的细胞分裂对于正常细胞的正常运转至关重要 其发育和丧失与肿瘤疾病有关 在人类和动物中。