Putative Antimicrobial Peptides in Fish: Using Zebrafish as a Representative

Antimicrobial peptides (AMPs) are a group of short peptides in vertebrates, independently or derived from big proteins (AMP precursors), for innate immune adaptation to fight against exogenous pathogens. Therefore, they provide attractive templates for us to develop new alternatives to antibiotics, which will relieve the threats of microbial resistance and drug residual. Fish reside in various environments; however, AMP research in fish have long been lagged behind. These highly diverse peptides in fish, regardless whether they are digested from proteins or not, constitute a sophisticate line for host defense. Exploring AMPs' detailed composition in fish will benefit us with a better understanding of them in vertebrates. This mini-review presents brief descriptions of AMPs and their research advances in fish, using zebrafish as the representative and comparing this model fish with well-studied amphibious mudskippers and tetraploid Atlantic salmon. Common features and species-specific characteristics among various fish provide valuable genetic resources for high-throughput development of novel antibiotic alternatives. In addition, the diversity and heterogeneity in tissue distribution also revealed the complex synergism of AMPs/AMP precursors. These big datasets of genomes and transcriptomes lay a solid foundation for theoretic researches and practical applications of AMPs in fish aquaculture and drug development.