Role of Calcium in Mitosis

人们普遍认为Ca是有丝分裂的调节因子。胞内自由的变化ıCa！可以调节控制有丝分裂装置的形成和/或功能的各种过程。最近的研究表明，免费ıCa！有丝分裂时的变化；然而，有报道关于这些变化的时间，动力学和位置的差异。这个问题将首先通过比较单一细胞类型（Tradescantia雄蕊毛）中Ca瞬变的时间和动力学来澄清，使用两种不同的Ca报告技术：负载砷偶氮iii的细胞的差异吸光度测量和注射水芹素的细胞的光发射。其次，比较不同来源的细胞类型（包括Tradescantia雄蕊毛、Haemanthus胚乳、蝾螈肺上皮和培养的袋鼠大鼠（PtK1）细胞）中Ca瞬变的时间和动力学，看看是否存在生物学变异。第三，g结合蛋白和磷脂酰肌醇循环成分在调节中期/后期转变中的作用将被检查。第四，通过将钙、钙调蛋白、gtp - γ - s、三磷酸肌醇或钙螯合剂直接注入活细胞，研究钙和钙调蛋白在调节染色体运动速率中的作用。第五，也是最后，有丝分裂后期可能发生的超微结构变化可能与染色体运动有关。使用快速冷冻和冷冻取代技术来阐明微管与其他微管或膜连接的结构和周期性，并观察这些变化是否与染色体运动有关。细胞分裂是地球上生命的一个基本方面。在真核细胞中，在每一次分裂中，遗传物质以有丝分裂染色体的形式有序地分布到子细胞中，对于个体生物和生命所有阶段的群体的正常维持是绝对必要的。这种有序分布发生的机制是一个复杂的现象，涉及结构和监管方面。在拟议的研究中，Hepler博士将扩展他之前在有丝分裂方面的工作，并明确解决该领域当前的技术争议。

It is widely assumed that Ca is a regulator of mitosis. Changes in the intracellular free ıCa! could modulate a variety of processes that control the formation and/or function of the mitotic apparatus. Recent studies show that free ıCa! changes during mitosis; however, there are reported differences concerning the timing, kinetics, and location of these changes. The problem will first be clarified by comparing the timing and kinetics of Ca transients in a single cell type (Tradescantia stamen hair) using two different Ca reporting techniques: differential absorbance measurements from arsenazo-III-loaded cells, and light emission from aequorin-injected cells. Second, the timing and kinetics of Ca transients will be compared in cell types of different origin, including Tradescantia stamen hair, Haemanthus endosperm, newt lung epithelium, and cultured kangaroo rat (PtK1) cells, to see if there are biological variations. Third, the role of G-binding proteins and components of the phosphatidylinositol cycle in regulating the metaphase/anaphase transition will be examined. Fourth, the roles of Ca and calmodulin in regulating the rate of chromosome movement will be studied, by microinjecting Ca, calmodulin, GTP-gamma-S, inositol triphosphate, or Ca chelators directly into the living cells. Fifth and finally, the possible occurrence of ultrastructural changes in the mitotic apparatus during anaphase that might be related to chromosome movement will be addressed, using rapid freezing and freeze-substitution techniques to elucidate the structure and periodicity of microtubule connections to other microtubules or to the membrane and to see if changes can be related to chromosome movement. Cell division is a fundamental aspect of life on earth. In eukaryotic cells, the orderly distribution of genetic material in the form of mitotic chromosomes to daughter cells at each division event is absolutely necessary for normal maintenance of individual organisms and populations at all stages of life. The mechanism whereby this orderly distribution occurs is a complex phenomenon involving structural and regulatory aspects. In the proposed studies, Dr. Hepler will extend his previous work on mitosis, as well as definitively address a current technical controversy in the field.