The capacity for arylsulfatase synthesis in synchronous and synchronized cultures of Chlamydomonas reinhardti.

The green algae Chlamydomonas reinhardti synthesizes arylsulfatase (arylsulfate sulfohydrolase EC 3.1.6.1) by derepression when the concentration of SO4-2-minus in the growth medium is less than about 5-10-minus 5 M. The following observations indicate that the arylsulfatase enzyme is stable while its mRNA was unstable: (1) The increase in enzyme activity stopped and remained constant after addition of cycloheximide to derepressed cells. (2) After readdition of SO4-2-minus the increase in enzyme activity continued at a lower rate whereafter it remained constant. (3) No decay of radioactivity was observed after readdition of SO4 2-minus in labelled enzyme protein isolated from pulse-labelled --S cells. The maximum rate of arylsulfatase synthesis. Measurements of this capacity in cells taken at different developmental stages from a selection synchronous and from a light-dark synchronized culture showed that: (1) Arylsulfatase was derepressible at all stages of the life cycle. (2) The same periodic capacity patterns were found, both with the synchronized and the synchronous cells. Furthermore, the rate of accummulation of RNA and protein changed in the same periodic manner during the life cycle as did the enzyme capacity.