Peptidomics and genomics analyses were used to study an anti-infection array of peptides of amphibian skin. 372 cDNA sequences of antimicrobial peptides were characterized from a single individual skin of the frog Odorrana grahami that encode 107 novel antimicrobial peptides. This contribution almost triples the number of currently reported amphibian antimicrobial peptides. The peptides could be organized into 30 divergent groups, including 24 novel groups. The diversity in peptide coding cDNA sequences is, to our knowledge, the most extreme yet described for any animal. The patterns of diversification suggest that point mutations as well as insertion, deletion, and "shuffling" of oligonucleotide sequences were responsible for the diversity. The diversity of antimicrobial peptides may have resulted from the diversity of microorganisms. These diverse peptides exhibited both diverse secondary structure and "host defense" properties.

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Nonlinear optical (NLO) frequency conversion is commonly used for generating midinfrared (MIR) lasers that offer light sources for a variety of applications. However, the low laser damage thresholds of NLO crystals used so far seriously limit the output power of MIR lasers. Here, a new nonlinear material 4H-SiC is demonstrated for producing MIR laser. Broadband MIR radiation ranging from 3.90 to 5.60 μm is generated in 4H-SiC by phase-matched difference-frequency generation for the first time.The results may open a door to practically utilize widebandgap semiconductors with high laser damage thresholds as NLO materials for high power output of MIR lasers.