SRA

Understanding the genetic mechanism of toxin resistance could provide us significant insights into the adaptive evolution and medical treatment with toxin. Currently it is not determined the detailed reason of toxin resistance in animals possessing toxin, which mainly refers to the mutation in voltagegated sodium channels and the toxin-binding proteins. Different species and populations of sea snail Nassarius could accumulate tetrodotoxin (TTX) and have caused serious people poisoning and death incident. Here two Nassarius species, N. succinctus and N. variciferus were used to investigate their genetic basis for TTX resistance by RNA-seq. Firstly, we revealed analogical genetic express patterns for both species, which was that the cellular process and metabolic process from biological process, and binding and catalytic activity from molecular function accounted for the top classification categories for the DEGs. Generally, the toxic samples showed analogical gene expression and the non-toxic samples showed analogical gene expression for both species. Secondly, for toxic and non-toxic samples of both species, the toxic samples generally produced more up-regulated genes than non-toxic samples. Thirdly, more importantly, we demonstrated some TTX-binding proteins from the DEGs, some of which have been reported in previous studies, and some of which are firstly found in the study. Finally, the D2 and D3 domains of voltagegated sodium channels of N. succinctus were retrieved, from which we retrieved several mutations including one site that was different from all other animals possess TTX. In conclusion, our study provided important genetic basis of TTX-resistance for dangerous sea snail from the genetic expression and mutation levels, which could contribute to the understanding of toxin-resistance and adaptive evolution. However, unfortunately, the complete sequences of voltagegated sodium channels of both species were not all recovered due to some potential reasons in sequence technology or others. In the follow-up study, we will employ more advanced technology and comprehensive samples to obtain their complete sodium channels sequences to fully understand the gene TTX-resistance in Nassarius.