Comparison of the embryotoxic effects of saporin, agrostin (type 1 ribosome-inactivating proteins) and ricin (a type 2 ribosome-inactivating protein)

Abstract

The effects of two type I ribosome-inactivating proteins, saporin and agrostin, and the type 2 ribosome-inactivating protein ricin and its constituent A and B chains, on the development of cultured mouse embryos, were investigated. Saporin and agrostin had similar embryotoxicity which was approximately 105 times weaker than that of ricin and its A and B chains, and the embryotoxicity of saporin and agrostin increased gradually with the dosage. In contrast, there was an abrupt rise in embryotoxictiy of ricin-A chain and B chain as the dose was raised from 10 to 20 ng ml-1. Saporin and agrostin did not affect the heart-beat and otic placode, but at 10 ng ml-1 ricin and 40 ng ml-1 ricin-A chain and B chain, all of the treated embryos exhibited abnormalities in heart-beat, yolk sac circulation, body axis, optic placode, otic placode, forelimb buds, branchial apparatus and cranial neural tube.