A study of the role of sulfhydryl groups in morphogenesis of the chick embryo

Summary The teratogenic effects on chick embryos of chloroacetophenone (CAP), a specific sulfhydryl blocking agent, are known to be reversible by a subsequent treatment with cysteine. However, cysteamine, the decarboxylation product of cysteine has been found to be unable to ameliorate the syndrome caused by CAP. It is suggested that CAP may act by binding the sulfhydryl of free cysteine in the cells of the organizer, thus indicating that cysteine may act as an inducing stimulus in primary organizer action. Post-nodal pieces of chick blastoderm exposed to the action of cysteine for 6 hours show differentiation of axial embryonic structures. Cysteamine has no such stimulatory effects on post-nodal pieces. This finding seems to further support the conclusion that cysteine may act as an inducing stimulus in primary organizer action.

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Zusammenfassung Die teratogenen Effekte von Chloroacetophenon auf Hühnchenembryonen sind bekannterweise reversibel durch Nachbehandlung mit Cystein. CAP ist ein Agens, das Sulphhydrylgruppen blockiert. Cysteamine revertiert die teratogenen Effekte nicht. Es wird vorgeschlagen, da CAP die Sulphhydrylgruppen freien Cysteins in den Zellen des Organisators blockiert, was heien würde, da Cystein ein induzierender Stimulus in der Organisatorwirkung wäre. Wenn post-nodale Stücke von Hühnchenblastoderm während 6 Std der Wirkung von Cystein ausgesetzt werden, entwickeln diese Axialelemente. Cysteamin zeigt diesen Effekt nicht. Diese Resultate stützen die Annahme, da Cystein als Induktor im primären Organisator wirken könnte.

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The author is grateful to Prof. B. R.Seshachar for constant encouragement and facilities for work. This work was supported by financial assistance from the Council of Scientific and Industrial Research, Government of India.