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Nuclear processes in Euplotes octocarinatus during conjugation.

H W Kuhlmann¹, K Heckmann

¹Zoologisches Institut der Universität Münster, Münster, FRG.

European Journal of Protistology

|December 1, 2012

Summary

This study details nuclear divisions in Euplotes octocarinatus during conjugation, revealing 35 chromosomes enter the macronuclear anlage. These findings illuminate ciliate nuclear development and genetic inheritance during cell division.

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Area of Science:

Cell Biology
Genetics
Protozoology

Background:

Conjugation in ciliates involves complex nuclear rearrangements.
The hypotrich ciliate Euplotes octocarinatus undergoes specific nuclear events during sexual reproduction.

Purpose of the Study:

To investigate the pregamic and metagamic nuclear divisions during conjugation in Euplotes octocarinatus.
To elucidate the development of new micro- and macronuclei.
To determine chromosome number and behavior during nuclear development.

Main Methods:

Phase contrast microscopy.
Aceto carmine staining.
Microphotography and timetable construction at 26°C.

Main Results:

Euplotes octocarinatus possesses n = 35 chromosomes.
All chromosomes enter the macronuclear anlage, undergo polytenisation, and fragment.
Sister nuclei frequently form pronuclei, suggesting isogenic co-conjugant lines.
No significant nuclear event differences were observed between heterotypic and homotypic conjugation pairs, except for a tendency of homotypic pairs to arrest and separate.
Regeneration or fusion of old macronuclear fragments with the new anlage was not observed.

Conclusions:

The study provides a detailed account of nuclear dynamics during Euplotes octocarinatus conjugation.
Findings support the formation of isogenic lines due to sister nuclei acting as pronuclei.
Observed nuclear events are specific to E. octocarinatus and differ from some other Euplotes species regarding macronuclear regeneration.