Gynogenesis Promoted by Irradiated Sperms in Ascidians

Ricerche sulla induzione del sistema nervoso nelle larve delle Ascidie

Summary Phallusia mamillata embryos at the 8-, 16-, 32- and 61-cell stages have been deprived of determined vegetative anterior blastomeres (deriving from, the A4.1 cells), with the purpose to sec which influence is exerted by such blastomeres in the induction of the nervous system. The results have been the following. 1 — The nervous system is not yet determined at the 64-cell stage. 2 — A neurali induction can be exerted even by a few blastomeres of the 64-ccll stage, containing cither entodermic or chordal material. 3 — Such inducing blastomeres arc those which give rise to the archenteron roof of the gastrula.

“BEP” RNAs and Proteins Are Situated in the Animal Side of Sea Urchin Unfertilized Egg, Which Can Be Recognized by Female Pronuclear Localization

Microsurgery experiments demonstrate that the animal side of the unfertilized sea urchin Paracentrotus lividus egg coincides with the side of the egg pronucleus location. It is demonstrated by means of in situ hybridization and immunostaining of whole mounts of animal or vegetal halves that the previously identified bep 1 and bep4 RNAs and their proteins are located in the animal part of the unfertilized egg and much less in the vegetal part. The addition of Fabs against BEP1 and BEP4 causes exogastrulation.

Sul cell-lineage delle ascidie