ABSTRACT
The animalizing effects of zinc on the development of eggs of the sea-urchin, Paracentrotus lividus, were studied and compared with the effects of other closely related metals: nickel, cobalt, manganese, and iron.
Nickel chloride (1/1,000) suppressed the formation of an archenteron. The blastulae were covered with short cilia. The apical tuft was not formed.
Nickel chloride (1 / 5,000 and 1110,000) induced the formation of radial larvae.
Cobalt chloride disturbed gastrulation and inhibited development.
Zinc was detected in the embryos at various stages of development by the formation of a deep red colour with dithizone. Zinc appeared to be distributed in the mesenchyme and entoderm of the young stages. In the pluteus, it appeared to be fixed in the pigment cells.
Nickel was located by the colour reactions with dimethylglyoxime and a-furil-dioxime. The colour was developed in the mesenchyme of the young blastula.
The colour reaction with dithizone was not modified by previous washings with Complexone (ethylene-diamine tetra-acetic acid) solution.
Zinc fixed in the embryos could be displaced by mercury ions.
With the addition of p-chloro-mercuribenzoic acid, the development of embryos in zinc chloride was blocked. The sulfhydryl groups do not appear to be essential for animalization by zinc ions.
The role of zinc in the animalization of sea-urchin eggs is discussed as a function of the formation of complexes between metal and proteins.
Dans un travail paru depuis l’envoi de ce mémoire, Rulon (Biol. Bull. Wood’s Hole, 1955,109, pp. 316-27) a observé la radialisation des larves de Sand Dollar traitées par le chlorure de zinc.