Protein Synthesis and Differentiation During Pulmonate Development

Abstract

An analysis of the changing patterns of protein synthesis during early development of Lymnaea palustris has been undertaken. An examination of the ingestion of capsule fluid protein suggests that after gastrulation 30 to 65% of the total embryo protein is undigested food protein. Starch gel electrophoresis reveals a sudden increase in the number of hydrolases from four to twenty-six immediately following the trochophore stage with the latter being present also in adult organs. Studies reported here and elsewhere demonstrate rhythmic changes in uridine incorporation during early cleavage which peaks at the trochophore stage. Continuous treatment of embryos with 50 to 100μ.g of actinomycin-D (AMD) starting at the 2-cell stage slowed development through the trochophore stage but did not prevent normal larval organ development. This AMD application reduced 3H uridine incorporation more than 90% but did not appreciably alter the pattern of total or 14C leucine pulse labeled peptides on sodium dodecyl sulfate (SDS) ultrathin slab electrophoresis gels. However, pronounced and numerous changes in the patterns of both labeled and unlabeled peptides were observed during development through 4 days with the most notable alterations occurring at the 2.5 post-gastrula stage. This was true in normal and continuously treated AMD embryos. The morphological and biochemical data suggest Lymnaea early development is controlled by stable maternal messenger RNA.