Trypsin Genes Are Regulated through the miRNA Bantam and Associated with Drug Sensitivity in the Sea Louse .

The role of genes in pharmacological sensitivity has been described in numerous arthropod species, including the sea louse . This ectoparasite species is mainly controlled by xenobiotic drugs in Atlantic salmon farming. However, the post-transcriptional regulation of genes and the molecular components involved in drug response remain unclear. In particular, the miRNA family has previously been associated with drug response in arthropods and is also found in , showing a high diversity of isomiRs. This study aimed to uncover molecular interactions among genes and miRNAs in the sea louse in response to delousing drugs. Herein, putative mRNA/miRNA sequences were identified and localized in the genome through genome mapping and blast analyses. Expression analyses were obtained from the mRNA transcriptome and small-RNA libraries from groups with differential sensitivity to three drugs used as anti-sea lice agents: azamethiphos, deltamethrin, and cypermethrin. The validation was conducted by qPCR analyses and luciferase assay of selected and genes identified from in silico transcript prediction. A total of 60 genes were identified in the genome, and 39 miRNAs were differentially expressed in response to drug exposure. Notably, expression analyses and correlation among values obtained from and revealed an opposite trend and potential binding sites with significant ΔG values. The luciferase assay showed a reduction of around 50% in the expression levels of the gene, which could imply that this gene is a potential target for . The role of genes and miRNAs in the pharmacological sensitivity of sea lice and the use of miRNAs as potential markers in these parasites are discussed in this study.