Ontogeny of αA and αB crystallin polypeptides during Rana temporaria lens development

Abstract

The ontogeny and localization of αA and αB polypeptide chains of α-crystallin were investigated in the developing lens of Rana temporaria, an anuran amphibian, using the indirect immunofluorescence staining method with heterologous antibodies directed against these two polypeptides. αA and αB crystallins are primary gene products and are translated by different mRNAs in mammals. Although they show about 6000 amino-acid sequence homology (Bloemendal, 1977), the αA cDNA of rat and mouse does not hybridize to αB mRNA (Dodemont et al., 1981; King and Piatigorsky, 1983). Antigenically too, αA and αB polypeptides have been shown to be different.

These two polypeptides were isolated from mouse lens native α-crystallin by SDS-gel electrophoresis and were injected into young rabbits to raise antibodies. These antibodies were tested by immunoblotting against R temporaria total lens soluble proteins before their use in the present investigation.

Results presented here show that in the developing lens of R. temporaria, αA appears earlier than αB, suggesting a differential gene activation. In addition, these two polypeptides could not be detected either in the developing lens epithelium or in the epithelium of young froglets (2–3 weeks post-metamorphosis).