LAUSR

ABSTRACT With an extensive range in tropical and subtropical waters of Indo‐Australian region and the Pacific coast of the American continent, the yellow‐bellied sea snake, Hydrophis platurus, is the most broadly distributed snake species on our planet. We report a comparative analysis of the mRNA and microRNA transcriptional profiles of the venom glands of Costa Rican juvenile and adult yellow‐bellied sea snakes, and correlate these datasets with the previously reported venom proteome gathered from an adult specimen of the same population of Playa del Coco. The transcriptomic profiles are qualitatively and quantitatively remarkably similar across both age classes, being overwhelmingly (>99%) dominated by only three toxin classes, three‐finger toxins (3FTx, 88%), phospholipases A2 (PLA2, 10–11%), and cysteine‐rich secretory proteins (CRISP, 1%). The only appreciable difference between the transcriptomes of juvenile and adult Costa Rican yellow‐bellied sea snake lies in the relative abundance of short and long neurotoxic 3FTxs. Comparison of venom gland transcriptome and venom proteome datasets suggest that the venom arsenal of adult H. platurus from Playa del Coco (CR) is subjected to post‐transcriptional modulation, involving repression of the translation of pelamitoxin a‐encoding mRNAs and enhancement of the translational activity of PLA2 and CRISP mRNAs. HIGHLIGHTSThe transcriptional activity of the venom gland of juvenile and adult H. platurus (Playa del Coco, CR) is reported.Venom gland miRNA datasets of juvenile and adult Costa Rican yellow‐bellied sea snake specimens were unveiled.Comparison of adult transcriptome and venom proteome suggest posttranscriptional modulation of venom composition by miRNAs.miRNA candidates for repressors and enhancers of venom gland toxin‐encoding mRNAs translation are proposed.