Amphibian Skin Secretions and Bio-adaptive Significance —Implications from Bombina maxima Skin Secretion Proteome

The studies on Bombina maxima revealed the rich molecular and functional diversity of amphibian skin secretion proteins and peptides. Discovered peptides from B. maxima skin secretions are three classes of antimicrobial peptides, bradykinin analogs and its gene associated peptides with diverse biological functions, proline-rich bombesin and its gene associated peptides, neuromedin U analog, Bv8 peptides, trefoil factors and protease inhibitors. The molecular and functional diversity, gene formation mechanisms and expression patterns of the peptides in B. maxima skin well reflect the molecular basis of bio-adaptation of the frog in certain living environments. In addition, B. maxima albumin with a heme b cofactor is widely distributed around the membranes of epithelial layer cells and within the stratum spongiosum of dermis in the skin, indicating its important roles in skin physiological functions, like water economy, metabolite exchange and osmoregulation, etc. The extraordinary complexity of peptides found in amphibian skin, coupled with the high probability of their novel molecular structures and possible counterparts in mammals, make amphibians an important target group in biomedical research and new drug development. Meanwhile, amphibian skin functional genome should be a nice model to study molecular biology of bio-adaptation, new gene formation and evolution.