Effects of cytochalasins on developing frog embryos: protection with L-cysteine and α-D-glucosamine.

Cytochalasins A, B and H (CA, CB and CH) brought about cellular disaggregation and mortality in the developing embryos of the frog, Microhyla ornata. All three cytochalasins exhibited a dose-response relationship. CA was the most potent and its effects were significantly reduced by simultaneous additon of L-cysteine, a sulph-hydryl compound. α-D-Glucosamine, a precursor of complex macromolecules important in cell adhesion, protected against the effects of CH. The effects of CB, however, were influenced neither by L-cysteine nor by α-D-glucosamine. The results revealed differences in the mechanism of action of these three cytochalasins.