Transcriptome Analysis of Tetrodotoxin Sensing and Action of Tetrodotoxin in the Brain of Tiger Puffer Takifugu rubripes By Next-Generation Sequencing

Recently, we clarified that tiger puffer Takifugu rubripes detects tetrodotoxin (TTX) by olfactory organ and accumulates TTX not only in liver and skin but also in central nervous system. We further conducted transcriptome analysis by next-generation sequencing for the olfactory epithelium and the brain of hatchery-reared non-toxic fish which were sensed and administered TTX in order to reveal TTX sensing and action of TTX in the brain. The sequencing output generated 2,042,732-8,641,449 reads. Differential gene expression between naive and TTX-sensed, or TTX-administered fish was analyzed by mapping the reads from each library to the nucleotide sequences of predicted transcripts in fugu genome that were cited from the ensembl database (FUGU4.0). There were no genes differentially expressed in the olfactory epithelium of TTX-sensed fish. In the olfactory epithelium of TTX-administered fish, 9 genes differentially expressed, 2 of which were up-regulated and 7 were down-regulated. In the brain of TTX-sensed fish, 3 genes were up-regulated and 1 was down-regulated. In the brain of TTX-administered fish, 5 genes were up-regulated and 8 were down-regulated. These genes included receptor (chemosensory) transporter protein 4 and vasoactive intestinal peptide which are responsible for expression of odorant receptor and appetite, respectively.