Larval ecology of prosobranch gastropods and its bearing on biogeography and paleontology

The larval ecology of prosobranch gastropods, which ranges from long pelagic plankto-trophic life histories to directly developing lecithotrophic ones, has a strong influence on larval dispersion. Because of low migrative ability in the post-larval stage, gastropod distribution must depend fundamentally on larval dispersion. It is probable that the modes of larval dispersion relate importantly to the mechanism by which prosobranch populations become isolated, and consequently to their modes of speciation. This idea is applicable for analysis of fossil material, for both biological and oceanographical information.     

Purification of Acetylcholinesterase from Sea Urchin (Hemicentrotus pulcherrimus) Embryos by Affinity Chromatography

Only one form of acetylcholinesterase (AchE) was detected in Hemicentrotus pulcherrimus embryos. In H. pulcherrimus embryos as well as in the other sea urchin embryos, AchE activity begins to increase rapidly after gastrula stage.
Purification of AchE from plutei has been carried out by the procedure including affinity chromatography. Purified AchE had the activity 14,600 times higher than that of homogenate, and the final yield of AchE was 8%. The enzyme seems to be electrophoretically homogeneous, and has a molecular weight of 3 × 10⁵ as determined by Sepharose CL–6B column chromatography.