The effect of chloramphenicol and cycloheximide on meiotic zoosporogenesis and mitotic gametogenesis in Ulva mutabilis.

Ulva mutabilis cells induced to form zoospores or gametes were exposed to chloramphenicol or cycloheximide during the 48 hours preparatory period. Chloramphenicol inhibited protein and RNA accumulation to the same degree at all concentrations, and appeared to have a general toxic effect. Cycloheximide at low concentrations inhibited primarily protein accumulation, while at higher concentrations it had also an effect on the net synthesis of RNA. Most of the inhibited cells were found in interphase, but a small percent of vegetative mitoses were observed and may indicate a return to this type of division. The gametophyte appeared to be more sensitive to chloramphenicol than the sporophyte. The effect of cycloheximide on the two processes seems to be more or less the same. A transition period, after which the sporulation process could no longer be inhibited, was found about 10 hours before the cells entered meiotic prophase in zoosporogenesis.