Effect of the micronucleus on cellular structures in several hypotrichous ciliates

Abstract

It is commonly believed that there is a sharp functional demarcation between the two types of nuclei of ciliated protozoa: the micronucleus for reorganization of the nuclear apparatus during sexual reproduction and the macronucleus for controlling somatic functions. This traditional view, however, has been critically re‐examined recently and correlative researches have shown that the micronucleus plays an essential role in the development of some ciliates. Here we report some morphological evidences about the effect of the micronucleus on cellular structures from amicronucleate cell lines of five hypotrichous ciliates (Pseudourostyla cristata, Pseudokeronopsis monilata, Paraurostyla weissei, Uroleptus piscis and Oxytricha faurei). All amicronucleate cell lines were generated by amputation and investigated by protargol staining. These observations manifest that micronucleus is indispensable to vigor and viability for P. weissei, to maintaining the integrity of adoral zone of membranelles (AZM) and/or undulating membranes (UM) for P. cristata, P. monilata and U. piscis, and to keeping regularity of cell shape as well as of the number and the structure of the macronuclei for O. faurei. These results suggest that the manifestations of the somatic function of micronucleus for different ciliates are varied and the close species might have a similar form of expression.This work was supported by a grant from NSFC (No: 30370210) to L. P. JIN.