Amphibians occupy a key phylogenetic position in vertebrates and evolution of the immune system. But, the resources of its transcriptome or genome are still little now. Bombina maxima possess strong ability to survival in very harsh environment with a more mature immune system. We obtained a comprehensive transcriptome by RNA-sequencing technology. 14.3% of transcripts were identified to be skin-specific genes, most of which were not isolated from skin secretion in previous works or novel non-coding RNAs. 27.9% of transcripts were mapped into 242 predicted KEGG pathways and 6.16% of transcripts related to human disease and cancer. Of 39 448 transcripts with the coding sequence, at least 1501 transcripts (570 genes) related to the immune system process. The molecules of immune signalling pathway were almost presented, several transcripts with high expression in skin and stomach. Experiments showed that lipopolysaccharide or bacteria challenge stimulated pro-inflammatory cytokine production and activation of pro-inflammatory caspase-1. These frog's data can remarkably expand the existing genome or transcriptome resources of amphibians, especially immunity data. The entity of the data provides a valuable platform for further investigation on more detailed immune response in B. maxima and a comparative study with other amphibians.

Significance: Pore-forming toxins are a common type of bacterial toxins and are important bacterial virulence factors. Aerolysin is produced by Aeromonas species. It is interesting that aerolysin-like proteins are also found in vertebrates. However, the physiological roles of these proteins are still unknown. Previously, a βγ-crystallin fused aerolysin-like protein (α-subunit) and trefoil factor (β-subunit) complex, hence named βγ-CAT, was identified in frogs. Here, we found that this complex is inducible by bacterial challenge. The complex was able to protect the host from microbial infection. It oligomerized along the endo-lysosome pathway to trigger lysosome destabilization and led to interleukin-1β maturation and secretion via inflammasome activation. Our present work provides functional evidence for uncovering the physiological roles of vertebrate-derived bacterial pore-forming toxin–like proteins.

Cationic antimicrobial peptides (AMPs) are considered as important candidate therapeutic agents, which exert potent microbicidal properties against bacteria, fungi and some viruses. Based on our previous findings king cobra cathelicidin (OH-CATH) is a 34-amino acid peptide that exerts strong antibacterial and weak hemolytic activity. The aim of this research is to evaluate the efficacy of both OH-CATH30 and its analog D-OH-CATH30 against clinical isolates comparing with routinely utilized antibiotics in vitro. In this study, 584 clinical isolates were tested (spanning 2013-2016) and the efficacy of the candidate peptides and antibiotics were determined by a broth microdilution method according to the CLSI guidelines. Among the 584 clinical isolates, 85% were susceptible to OH-CATH30 and its analogs. Both L-and D-OH-CATH30 showed higher efficacy against (toward) Gram-positive bacteria and stronger antibacterial activity against nearly all Gram-negative bacteria tested compare with antibiotics. The highest bactericidal activity was detected against Acinetobacter spp., including multi-drug-resistant Acinetobacter baumannii (MRAB) and methicillin-resistant Staphylococcus aureus (MRSA). The overall efficacy of OH-CATH30 and its analogs was higher than that of the 9 routinely used antibiotics. OH-CATH30 is a promising candidate drug for the treatment of a wide variety of bacterial infections which are resistant to many routinely used antimicrobial agents.

Characterization and phylogenetic analysis of Krüppel-like transcription factor (KLF) gene family in tree shrews ( Tupaia belangeri chinensis ) Characterization and phylogenetic analysis of Krüppel-like transcription factor (KLF) gene family in tree shrews (Tupaia belangeri chinensis)