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Nuclear Division in the Dinoflagellate Gonyaulax tamarensis
Abstract
SUMMARY
The interphase nucleus of Gonyaulax tamarensis is U-shaped with a lens-shaped central body lying between the arms of the U. At the beginning of division the chromosomes become arranged around the central body and can be seen to be split into pairs of chromatids which are held together by relational coiling. The pairs lie across the plane of the equator. The beginning of anaphase is obscure but as the chromatids separate into the daughter nuclei they exhibit a variety of arrangements which seem to exclude the possibility of localized centromere and normal spindle. The central body divides into two at this stage. During telophase the ball of chromosomes breaks open and the chromosomes lose some condensation as they twist together and the U-shaped interphase nucleus is re-established. In some of these features Gonyaulax differs from other dinoflagellates which have been studied as well as exhibiting a vastly different nuclear division to that found in higher organisms. The central body behaves like the endosome of the Euglenophyta but also has similarities with the central spindle reported from certain flagellates and diatoms.
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© Society for General Microbiology 1964