Tetrodotoxin distribution in natural hybrids between the pufferfish species Takifugu rubripes and Takifugu porphyreus
Natural hybrids among pufferfishes belonging to the genus Takifugu have been reported occasionally, yet very little is known about their toxicity. To study the tetrodotoxin (TTX) distribution in the bodies of natural hybrids, 10 putative hybrids between Takifugu rubripes and Takifugu porphyreus, which differ in the toxicity of the skin (the former is hardly toxic whereas the latter shows high toxicity), were collected from the coastal waters off Yamaguchi and Shimane Prefectures and used for genetic and biochemical analyses. Genetic identification of parental species using amplified fragment length polymorphism and mitochondrial DNA markers revealed that five and four individuals were F1 hybrids between T. rubripes females and T. porphyreus males and those of the opposite cross, respectively. In addition, the remaining hybrid was a first-generation backcross to T. rubripes. Quantitative analysis of TTX by high performance liquid chromatography-fluorescence detection showed that the skin of F1 hybrids has TTX, differing from T. rubripes, suggesting the possibility of a dominant mode of inheritance of toxicity of the skin. TTX was detected in the muscle of F1 hybrids only between T. porphyreus females and T. rubripes males, albeit at a low concentration of < 0.1–1.1 µg/g. The TTX concentrations of toxic tissues of the one backcross individual were within the range of variation of those of T. rubripes.
KeywordsHybrid pufferfish Hybridization Tetrodotoxin Takifugu rubripes Takifugu porphyreus
We are grateful to Ryo Shimoyama, Ririko Ideguchi, and Masato Umeeda for their assistance with the experiment. This work was supported in part by grants from the Project of the NARO Bio-oriented Technology Research Advancement Institution (the special scheme project on regional developing strategy, Project No. 16822337) and by JSPS KAKENHI (No. 25440227).
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