Particularities of dinomitosis pattern in different dinoflagellates

Abstract

Dinoflagellates are primitive unicellular eukaryotes showing nuclear and mitotic peculiarities. Their chromosomes are visible and remain condensed at all stages of the cell cycle, they do not have true histones, the nuclear envelope persists during mitosis, whereas the mitotic spindle is usually cytoplasmic, making their division a complex process called dinomitosis. While there presently exist about 2000 species of dinoflagellates, only a few of them have been studied at the cellular level. Here, we show that dinomitosis differs greatly in several species, namely, Akashiwo sanguinea, Karenia brevis, Oxyrrhis marina and Prorocentrum micans. We suggest that dinoflagellates, which represent an heterogeneous group in various cellular, physiological and structural aspects, are also heterogeneous in terms of mitosis. Dinoflagellates must be regarded as an >experimental group> making an evolutive link between bacteria, fungi and higher eukaryotes in terms of cell division processes, that we call dinomitoses