EVIDENCE FROM SEA URCHIN-SAND DOLLAR HYBRID EMBRYOS FOR A NUCLEAR CONTROL OF ALKALINE PHOSPHATASE ACTIVITY

Abstract

1. Alkaline phosphatase estimations upon sea urchin embryos (S. purpuratus) showed a slow rate of increasing activity up to the pluteus stage while sand dollar embryos (Dendraster excentricus) showed a very rapid increase up to this same stage. 2. Hybridization between Strongylocentrotus purpuratus ♀ and Dendraster excentricus ♂ resulted in alkaline phosphatase activity at the prism stage which was intermediate between that of the two homologous species and higher than that of the maternal species. This is interpreted as indicating a nuclear control of alkaline phosphatase activity. 3. Addition of substrate (0.1 M sodium β glycerophosphate) to cultures of developing S. purpuratus embryos did not affect an increase in acid or alkaline phosphatase activity.