Cycloheximide effect on DNA degradation and delta-crystallin synthesis in terminally differentiating lens cells

Low concentrations of a protein synthesis inhibitor, cycloheximide, were added throughout the process of in vitro differentiation of 11-day old embryonic chick lens cells. We found with low concentrations of cycloheximide (0.01 to 0.03 microgram/ml, 3 days of culture), that there was an almost complete delay of DNA degradation as observed on alkaline sucrose gradient. Identical concentrations and exposure time had no blocking effect on increased delta-crystallin synthesis as detected by immunoprecipitation and electrophoresis. Higher concentrations of cycloheximide (0.1 to 1 microgram/ml) showed a marked effect on DNA size and a net inhibition on delta-crystallin synthesis. Thus a selective effect of low doses of cycloheximide was observed on terminal differentiation suggesting that there was not a relationship between DNA degradation and delta-crystallin synthesis in these short term experiments. The investigations of minor proteins could be of interest as they may have a crucial role in intact nuclei cataracts.