De Novo Assembly and Characterization of Venom Gland Transcriptome for Rhabdophis lateralis

Rhabdophis lateralis is a snake species within the family Natricidae, which is widely distributed across mainland China, Russia, and Korea. Although this species was once thought to be non-venomous, there are quite a few cases demonstrating its bite could be fatal. In this study, we performed de novo assembly and analysis of the transcriptome data from the Duvernoy's gland of R. lateralis, aiming to characterize its venom transcriptome and reveal the molecular basis of its toxicity. Among 6196 annotated transcripts, 77 were identified as potential toxin transcripts belonging to 26 toxin families. The most highly expressed toxin family was the SVMP family, accounting for 51.10% of the total toxin expression. The other notable toxins included cysteine-rich secretory proteins (CRISPs, 22.36%), c-type lectins (CTLs and snaclecs, 12.13%), and three-finger toxins (3Ftxs, 6.36%). Phylogenetic analyses indicated that SVMPs, CRISPs, and three-finger toxins (3FTxs) are evolutionarily conserved within Colubridae, whereas CTLs likely arose through convergent evolution. All identified SVMPs were classified as P-III type, with one sequence displaying a unique deletion distinct from conventional truncation patterns. The predominantly expressed CTLs are more likely to combine into dimers, exerting coagulation activity. This study provides an insight into the toxin gene expression in the Duvernoy's gland of R. lateralis, which will benefit future research into the ecological and pharmacological significance of toxins in the genus Rhabdophis.