Nuclear groups and diversity of macronuclei of Kentrophoros tubiformis (Ciliophora, Karyorelictida) from the Japan sea

• Published in: European journal of protistology Vol. 32; no. 3; pp. 327 - 335
• Main Authors: Raikov, Igor B., Kovaleva, Valentina G.
• Format: Journal Article
• Language: English
• Published: Elsevier GmbH 30-08-1996
• Subjects: Ageing of macronuclei; Ciliophora; Karyorelictid ciliates; Kentrophoros tubiformis; Macronuclei; Marine; Micronuclei; Nuclear groups; Pycnosis; INW, Japan Sea; Pycnosis; LMA; Macronuclei; C; PMA; F; Karyorelictid ciliates; AM; N; S; V; Micronuclei; NE; Nuclear groups; DMA; IMA; MI; Ageing of macronuclei
• ISSN: 0932-4739; 1618-0429
• DOI: 10.1016/S0932-4739(96)80057-5

The nuclear apparatus of the Far-Eastern form of
Kentrophoros tubiformis is represented by 7–12 nuclear groups, each consisting of a variable number of macronuclei (4–8) and micronuclei (2–4). There is no common membrane around individual groups. The micronuclei are filled with condensed chromatin and have no nucleoli and very little free karyolymph, mainly under the envelope. The micronuclear envelope shows two membranes but has no pore complexes. Developing macronuclei contain numerous small chromatin bodies and, later, also small nucleoli. Adult macronuclei are strongly variable in appearance: some have transparent karyolymph, others dark karyolymph where other components of these nuclei are poorly discernible. “Dark” macronuclei condense to smaller size and look pycnotic. The macronuclei, both “light”, “dark” and intermediate ones, contain several medium-sized nucleoli of compact type and several chromocentres. Some macronuclei contain a large sphere of microfilamentous structure and packs of thicker fibres usually adjacent to chromocentres and/or to the sphere. The macronuclear envelope displays pore complexes. “Dark” macronuclei also often show “blebbing” of the nuclear envelope (with extension of the perinuclear space). In pycnotic macronuclei, only the sphere and the chromocentres remain visible. Condensation of some macronuclei is possibly related to their aging and degeneration.