Control of cell division in a green alga,Ankistrodesmus gracilis

摘要

The proliferation pattern ofAnkistrodesmus gracilis, a species of Chlorococcales, is described. Under standard conditions, various proliferation patterns; di-, tri-, tetra-, or multichotomical cell division were observed. Light-dark diurnal rhythms, LD 12 : 12 and 14 : 10 induced growth patterns which formed two- to several-ten-celled colonies, whereas the rhythms LD 16 : 8 to 20 : 4 induced only the formation of two-celled colonies. These inductions were observed at a cell density of 4.0×106cells/ml. Dichotomical cell division occured at a cell density of more than 1.5×107cells/ml. No influence of self-shading on the pattern of colony formation was detecte