Cytoplasmic RNA and Enzyme Activity During the Meiotic Prophase in Cosmos bipinnatus

Abstract

This chapter discusses the changes in the content of acetic-alcohol fixable RNA and in enzyme activity that have been followed in meiocyte cytoplasm during the meiotic prophase in Cosmos bipinnatus , Compositae, by quantitative and semiquantitative cytochemical methods. The RNA content of the meiocyte cytoplasm is estimated by cytophotometry of 6 μm sections after pyronin Y or azure B staining. After an initial rise, which may not be significant, the RNA content per meiocyte falls abruptly between zygotene and pachytene to a value less than half of that measured at leptotene. The chapter discusses a study that was conducted in an attempt to detect the changes in enzyme activity that might be associated with ribosome dissolution; for this, the prophase meiocytes of Cosmos was surveyed for lysosome enzymes, particularly acid phosphatase and ribonuclease. The observations on ribonuclease activity were less clear-cut because of higher nonspecific staining and the fact that the procedure gave some reaction in the cell nucleus at all stages. The results show that there are phase-specific changes in cytochemically detectable enzyme activity in the meiocyte cytoplasm during prophase.