A Sensitive Stage in Synchronized Cultures of Chlorella.

Abstract

In the course of the life cycle of synchronized Chlorella pyrenoidosa (light-dark changes of 16 hrs. and 12 hrs. darkness) a sensitive stage has been observed after about 6-8 hrs. of illumination. Cold shocks (2 hrs. from 30[degree] to 4[degree]C) during this stage induce an abnormal cell metabolism, indicated by a transient inhibition of cell growth and cell division, and by a reversible depression of chlorophyll content. Some remarks are included concerning methods of synchronization, and the relation between the life cycle of the cells and the external factors inducing synchronized growth.