Relationships between the release of acid, the cortical reaction, and the increase of protein synthesis in sea urchin eggs

Abstract

AbstractCortical granule discharge has been separated from Na+‐‐dependent acid release and the increase of protein synthesis in sea urchin eggs. When 2% egg suspensions are inseminated or treated with the ionophore A23187 in normal sea water, cortical granule discharge is induced and the pH of the suspensions decrease approximately 0.35 pH units. When a similar suspension is treated with A23187 in Na+‐free sea water, cortical granule discharge is induced, but the pH of the suspension decreases only 0.05 pH units, and the rate of protein synthesis remains at the level of the unfertilized egg. When 0.05 M NaCl is added to this suspension, the pH decreases the remaining 0.30 pH units, and the rate of protein synthesis increases to the level of the fertilized egg. Thus, there appear to be two components of acid release from sea urchin eggs at fertilization: (1) a Na+‐independent component which correlates with cortical granule discharge; and (2) a Na+‐dependent component which correlates with the increase of protein synthesis.