©2007 European Journal of Histochemistry

Beta-keratins are responsible for the mechanical resistance of scales in reptiles. In a scaleless crotalus snake (Crotalus atrox), large areas of the skin are completely devoid of scales, and the skin appears delicate and wrinkled. The epi-dermis of this snake has been assessed for the presence of beta-keratin by immunocytochemistry and immunoblotting using an antibody against chicken scale beta-keratin. This antibody recognizes beta-keratins in normal snake scales with molecular weights of 15-18 kDa and isoelectric points at 6.8, 7.5, 8.3 and 9.4. This indicates that beta-keratins of the stratum corneum are mainly basic proteins, so may inter-act with cytokeratins of the epidermis, most of which appear acidic (isoelectric points 4.5-5.5). A beta-layer and beta-ker-atin immunoreactivity are completely absent in moults of the scaleless mutant, and the corneous layer comprises a multi-layered alpha-layer covered by a flat oberhautchen. In con-clusion, the present study shows that a lack of beta-keratins is correlated with the loss of scales and mechanical protec-tion in the skin of this mutant snake. Key words: snake; scaleless; beta-keratin; ultrastructure; immunocytochemistry, immunoblotting