Changes in esterase and cholinesterase isozymes in normally developing, animalized and radialized embryos of Arbacia punctulata

Abstract

The ontogeny of esterase and cholinesterase isozymes in normally developing, animalized, and radialized sea urchin embryos was studied using the technique of disc electrophoresis on polyacrylamide gels. Using the substrate alpha-naphthyl acetate, seven esterases, none of which was inhibited by preincubation with eserine sulfate, were present in the unfertilized egg. The pattern of non-specific esterases remained similar until after the blastula stage. The number of esterase isozymes increased in each of the gastrula, prism, and pluteus stages. No cholinesterase activity was observed until gastrula and prism stages. Five additional cholinesterase isozymes were unique to plutei. Animalized embryos exhibited a reduction in the number of esterase and cholinesterase isozymes as compared to controls. Pluteus-animalized larvae had the cholinesterase isozymes unique to the pluteus stage of normal development. It was suggested that these isozymes might be involved in ectodermal ciliary function. Missing esterase and cholinesterase bands in animalized embryos were correlated with: (a) lack of ciliary coordination, or (b) inability to gastrulate and differentiate the skeleton. Radialized embryos had similar isozyme patterns to controls. As these larvae contain structures formed from all three germ layers, it was suggested that this developmental abnormality might be due to quantitative, rather than qualitative, changes in enzymes.