Conclusion
This study revealed the genetic patterns of TTX accumulation and resistance in two Nassarius species by transcriptome analysis. For gene expression, the cellular and metabolic process and binding and catalytic activity accounted for the top classification categories for both N. succinctus and N. variciferus . The toxic specimens showed more upregulated genes compared with the non-toxic specimens bothN. succinctus and N. variciferus . The heat shock protein and cytochrome c oxidase subunit were found as the most significant different expression genes between all the toxic and non-toxic groups, which are mainly related with the metabolic mechanism of detoxification and various diseases. Compared with other animals possessing toxin resistance, one new amino acid ā€œLā€ was found in the sodium channels ofN. variciferus , which could possibly be the mutation for blocking the TTX-binding. Future studies should focus on exploring the complete sodium channel genes of various Nassarius species and detailed metabolic pathways for TTX resistance in Nassarius .