DIEL PHASING OF THE CELL‐CYCLE IN THE FLORIDA RED TIDE DINOFLAGELLATE, GYMNODINIUM BREVE

Publisher Website
Google Scholar
Abstract
The diel cycle is a key regulator of the cell‐cycle in many dinoflagellates, but the mechanisms by which the diel cycle entrains the cell‐cycle remain poorly understood. In this study, we describe diel phasing of the cell‐cycle in the Florida red tide dinoflagellate Gymnodinium breve Davis, determine the diel cue which serves to entrain the cell‐cycle, and provide evidence for the presence of cyclin‐dependent kinase (CDK), a cell‐cycle regulator which may be responsive to this cue. Four laboratory isolates from the West Coast of Florida were compared. When grown on a 16:8 h LD cycle, all isolates displayed phased cell division, with the S‐phase beginning 6–8 h into the light phase, and mitosis following 12–14 h later, as determined by flow cytometry. A naturally occurring bloom of G. breve, studied over one diel cycle, displayed diel cell‐cycle phasing similar to that in the laboratory cultures, with the S‐phase beginning during daylight and the peak of mitosis occurring approximately 4 h after sunset. In the laboratory cultures, the dark/light “dawn” transition was found to provide the diel cue which serves to entrain the G. breve cell‐cycle, whereas the light/ dark “dusk” transition did not appear to be involved. Evidence for the presence of CDK in G. breve was obtained using two approaches: (1) identification of a 34‐kDa protein, immunoreactive to an antibody against a conserved amino acid sequence (α‐PSTAIR) unique to the CDK protein family and (2) inhibition of the cell‐cycle by olomoucine, a selective CDK inhibitor. Together, these results provide the basis from which one can begin addressing mechanisms by which the diel cycle regulates the cell‐cycle in G. breve.

This publication has 0 references indexed in Scilit: