EVOLUTION OF NUCLEAR DIVISION STRATEGIES WITHIN THE FISSION YEAST CLADE

Abstract

Mitosis is a process where two identical sets of chromosomes are segregated equally to two daughter cells. There is a spectrum of varying forms of mitoses. A fundamental question is how eukaryotic cells adapt the basic mitotic machinery to evolve different nuclear division strategies. Here, I show that Schizosaccharomyces japonicus undergoes semi-open mitosis, unlike its sister species, Schizosaccaromyces pombe which undergoes closed mitosis. I demonstrated that the anaphase nucleus in Schizosaccharomyces japonicus does not expand like in Schizosaccaromyces pombe?s but breaks during late anaphase. Furthermore, the LEM domain protein, Man1 is also integral for mitotic nuclear structuring in Schizosaccharomyces japonicus. My work suggests that mitotic control of the nuclear surface area may determine the choice between the nuclear envelope breakdown and a fully closed division. Performing comparative cell biology studies using two closely related fission yeast species can provide unique insights into the evolution of mitosis.