Herbert Stern

Polymerase and kinase activities in relation to RNA synthesis during meiosis.

This paper is an attempt to explain a phenomenon observed by several investigators, the fluetnation.s in RNA synthesis during meiosis (T a y l o I 1958; H o t t a and S t e r n 1963; M o n e si 1964). The meiotic cells of tulip (Tulipa gesneriana) are fairly synchronous in development and they may therefore ,be collected at .different cytological stages for biochemical analysis. Since the relative levels of RNA synthesis at the different stage,s .are known, a direct comparison may be made between the behavior of the RNA synthetase system, i n s i t u and i n v i t r o . Three possible mechanisms for regulating the gross level of RNA synthesis in meiotic cells have been tested: RNA polymerase activity, availability of template DNA, and precursor supply as determined ,by kinase activities. On the assumption that i n v.i t r o activities reflect in v i v o capacities, variations in the activities of those mechanisms which limit the level of RNA synthesis in the living meiotic cell should parallel the vari,ations in RNA synthesis manifested ,by such a cell during its development. This report will show that among the mechanisms listed, only nueleoside kinase fulfills this requirement.

FACETS OF INTRACELLULAR REGULATION OF MEIOSIS AND MITOSIS1

Publisher Summary This chapter discusses a study to analyze facets of intracellular regulation of meiosis and mitosis. In the study, the response of meiotic and mitotic cells to azaguanine, chloramphenicol, ethionine, and 5-methyltryptophan were studied. It was shown that these reagents are capable of interfering with the progress of the two cycles, the type of interference depending upon the stage of the cycle at which the inhibitors reach the cell. In the case of meiosis, most of the major disruptions observed could occur by inhibiting synthesis of protein up to pachytene or diplotene. These included failure of spindle action, arrest of second division, inhibition of cytokinesis, aberrant wall synthesis, and alterations in chromosome morphology. In the case of mitosis, the study was mainly concerned with a single enzyme—thymidine phosphorylase—and it was shown that reagents that inhibit protein synthesis also inhibit the appearance of that enzyme provided that the reagent is applied at least 1 day prior to its normal appearance.