Laboratory of Fish Biology, Department of Animal Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan.
Laboratory of Organic Chemistry, Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan.
Chem Senses. 2022 Jan 1;47. doi: 10.1093/chemse/bjac011.
Toxic puffers accumulate their defense substance (tetrodotoxin; TTX) through the food chain. Although the previous study suggests that 5,6,11-trideoxyTTX, a nontoxic TTX analog detected simultaneously with TTX in toxic puffers or their prey, acts as an olfactory chemoattractant for grass puffers, it is unclear whether toxic puffers are commonly attracted to 5,6,11-trideoxyTTX, and which types of olfactory sensory neurons (OSNs) detect 5,6,11-trideoxyTTX. Here, we demonstrated that green spotted puffer, a phylogenetically distant species from the grass puffer, is attracted to 5,6,11-trideoxyTTX. 5,6,11-TrideoxyTTX administration made green spotted puffers stay longer at the administered site, whereas a food odor (l-Arg) made them actively swim throughout the aquarium. Attractive responses were not observed when TTX or its vehicle was administered, nor when 5,6,11-trideoxyTTX was administered to anosmic fish. Furthermore, double immunohistochemistry with activity marker and crypt OSN marker antibodies labeled oval cells with apical invagination on the olfactory epithelium surface treated with 5,6,11-trideoxyTTX. These results suggest that 5,6,11-trideoxyTTX acts as an olfactory chemoattractant detected by crypt OSNs, and attraction to 5,6,11-trideoxyTTX odor appears to be a trait shared by toxic puffers for social communication or effective toxification.
有毒河豚通过食物链积累其防御物质（河豚毒素；TTX）。尽管之前的研究表明，同时在有毒河豚或其猎物中检测到的无毒 TTX 类似物 5,6,11-去氧 TTX（5,6,11-trideoxyTTX）作为草河豚的嗅觉化学引诱剂起作用，但不清楚有毒河豚是否通常被 5,6,11-去氧 TTX 所吸引，以及哪种类型的嗅觉感觉神经元（OSN）检测到 5,6,11-去氧 TTX。在这里，我们证明了与草河豚在系统发育上相距较远的绿斑河豚对 5,6,11-去氧 TTX 有吸引力。5,6,11-去氧 TTX 的给药使绿斑河豚在给药部位停留的时间更长，而食物气味（l-Arg）使它们在整个水族馆中积极游动。当给予 TTX 或其载体时，或当给予 5,6,11-去氧 TTX 给嗅觉丧失的鱼时，没有观察到有吸引力的反应。此外，用活性标记物和隐窝 OSN 标记物抗体的双重免疫组织化学处理 5,6,11-去氧 TTX 后，在嗅觉上皮表面用顶端内陷标记的椭圆形细胞。这些结果表明，5,6,11-去氧 TTX 作为一种嗅觉化学引诱剂，由隐窝 OSN 检测到，并且对 5,6,11-去氧 TTX 气味的吸引力似乎是有毒河豚用于社交交流或有效中毒的特征。
