Main Content

The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 4858

Igor B. Raikov and Valentina G. Kovaleva; The Nuclear Complexes ("Composite Nuclei") in the Genus Tracheloraphis: a Comparative Ultrastructural Study. Arch.Protistenk 144:329-342, 1994

Reprint

In File

Notes

Five most typical species of marine psammobiotic ciliates of the genus Tracheloraphis show the union of their entire nuclear apparatus, which consists of several or many macronuclei of the paradiploid never-dividing type and several to many micronuclei, into one or several nuclear complexes ("nuclear capsules", "composite" or "complex" nuclei). Each of these complexes consists of four to 22 macronuclei in peripheral position and two to six micronuclei in central position. However, true fusion of the nuclei never occurs, the envelopes of each individual macro- and micronucleus remaining intact and separate from each other. The nuclei are united with a system of granular endoplasmic reticulum cisternae that occur between the nuclei. From the outside, each nuclear complex is covered by a single additional agranular membrane which passes from one macronucleus onto another and represents the proximal membrane of the voluminous perinuclear cisterna of the smooth endoplasmic reticulum. Only a thin rim of ground cytoplasm occurs between this membrane and the envelopes of the outer-most nuclei but more of it is present between the macronuclei and around the micronuclei. The macronuclei of representatives of this genus typically contain nuclear bodies in form of protein crystalloids in addition to chromocentres and nucleoli; the micronuclei contain compact, usually spongy chromatin and no nucleoli.