Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo, 113-8657, Japan.
School of Marine Biosciences, Kitasato University, Sagamihara, Kanagawa, 252-0373, Japan.
Mar Biotechnol (NY). 2024 Dec;26(6):1367-1374. doi: 10.1007/s10126-024-10377-x. Epub 2024 Oct 2.
Pufferfish of the genus Takifugu possess tetrodotoxin (TTX), known as "pufferfish toxin" and it is believed that pufferfish eggs and newly hatched larvae utilize TTX as a defensive substance against predators. However, the mechanism for the placement of TTX to specific cells on the larval body surface during the developmental process remains unknown. In this study, we clarify the distribution and characteristics of TTX-rich cells. We performed whole-mount immunohistochemistry (IHC) using anti-TTX monoclonal antibody on larvae of two pufferfish species, Takifugu rubripes and Takifugu alboplumbeus, just after hatching. This allowed observation of the TTX location and compared it with those of wheat germ agglutinin (WGA)-positive (periodic acid-Schiff (PAS)-positive) cells for mucous cells and IHC using anti-Na/K-ATPase (NKA) monoclonal antibody for ionocytes. As a result, uniformly scattered localization of TTX-rich cells was commonly observed in the epidermis of the larvae of the two Takifugu species. TTX-rich cells were WGA-negative (PAS-negative) and structurally distinct from NKA-positive cells, suggesting that TTX-rich cells are unreported small cells unique to pufferfish skin, but not mucous cells nor ionocytes.
河豚属鱼类拥有河豚毒素（TTX），也被称为“河豚毒素”，人们认为河豚鱼的卵和刚孵化的幼虫利用 TTX 作为防御物质来抵御捕食者。然而，在发育过程中，TTX 被放置在幼虫体表面特定细胞上的机制尚不清楚。在这项研究中，我们阐明了富含 TTX 的细胞的分布和特征。我们使用抗 TTX 单克隆抗体对刚孵化的两种河豚鱼，红鳍东方鲀和暗纹东方鲀的幼虫进行了全胚胎免疫组织化学（IHC）。这样可以观察 TTX 的位置，并将其与小麦胚凝集素（WGA）阳性（过碘酸雪夫（PAS）阳性）的黏液细胞以及抗 Na/K-ATPase（NKA）单克隆抗体的免疫组织化学进行比较，用于离子细胞。结果，在两种河豚鱼幼虫的表皮中普遍观察到均匀分散的富含 TTX 的细胞定位。TTX 丰富的细胞 WGA 阴性（PAS 阴性），与 NKA 阳性细胞结构不同，表明 TTX 丰富的细胞是河豚鱼皮肤中独特的、未报道的小细胞，而不是黏液细胞或离子细胞。
