Role of Calcium in Mitosis

人们普遍认为，钙是有丝分裂的调节因子。细胞内游离ı钙的变化！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，免费的ı钙！在有丝分裂过程中的变化；然而，关于这些变化的时间、动力学和位置有报道的不同。这个问题将首先通过比较单一细胞类型(紫露草雄蕊毛)中钙瞬变的时间和动力学，使用两种不同的钙报告技术来澄清：来自偶氮砷III负载细胞的差示吸收测量，以及来自水飞蓟素注射的细胞的光发射。其次，将比较不同来源的细胞类型，包括紫露草雄蕊毛、海曼莎胚乳、纽特肺上皮和培养的袋鼠细胞(PtK1)中钙瞬变的时间和动力学，以确定是否存在生物变异。第三，将研究G结合蛋白和磷脂酰肌醇循环的成分在调节中期/后期转变中的作用。第四，通过直接向活细胞内微量注射钙、钙调素、谷丙转氨酶-γ-S、三磷酸肌醇或钙络合剂，研究钙和钙调蛋白在调节染色体运动速度中的作用。第五，也是最后，在有丝分裂后期可能发生的可能与染色体运动有关的超微结构变化，将使用快速冷冻和冷冻替代技术来阐明微管与其他微管或膜的连接的结构和周期，并了解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，在每个分裂事件中，遗传物质以有丝分裂染色体的形式有序地分布到子细胞，对于个体生物体和种群在生命各个阶段的正常维持是绝对必要的。这种有序分配的发生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，海普勒博士将扩展他之前在有丝分裂方面的工作，并最终解决该领域目前的一个技术争议。

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.