Marine pufferfish contain tetrodotoxin (TTX), an extremely potent neurotoxin. All species of the genus Takifugu accumulate TTX in the liver and ovaries, although the tissue(s) in which it is localized can differ among species. TTX is the major defense strategy the pufferfish appears to use against predators. TTX is also used as a male-attracting pheromone during spawning. Here we demonstrate an additional (and unexpected) use of maternal TTX in the early larval stages of the Takifugu pufferfish. Predation experiments demonstrated that juveniles of all the species of fish used as predators ingested pufferfish larvae, but spat them out promptly. Liquid Chromatography-Tandem Mass Spectrometry (LC-MSMS) analysis revealed that the pufferfish larvae contain a small quantity of TTX, which is not enough to be lethal to the predators. Immunohistochemical analysis with anti-TTX monoclonal antibody revealed that the TTX is primarily localized in the body surface of the larvae as a layer of protection. Our study showed the female parent of the Takifugu pufferfish vertically transfers TTX to the larvae through its accumulation in the ovaries, and subsequent localization on the body surface of the larvae.

The tiger pufferfish (fugu), Takifugu rubripes, is a model fish that has had its genome entirely sequenced. By performing genomewide linkage analyses, we show that the sex of fugu is determined by a single chromosomal region on linkage group 19 in an XX-XY system.

This is the first study revealing the differences in gut microbiota of captive dolphins among facilities. Our findings will provide valuable information for improving the health management of dolphins.

Development of a Microtiter Plate Enzyme-linked Immunosorbent Assay for 17ƒ¿, 20ƒÀ-21-trihydroxy-4-pregnen-3-one, a Teleost

27th day in 16L group. During 28 days, GSIs increased significantly in both photoperiod groups (9L, P<0.001; 16L, P<0.05) as compared to that in the initial controls (Fig. 3). Bitterling Maturation and Environmental Factors 63 (9L) or a long (16L) photoperiod on ovarian GSI in Rhodeus ocellatus ocellatus during the prespawning and spawning periods. Experi ment was started on Jan. 19, 1977. Fish were sampled on the 28th and 108th days thereafter. On the 53rd day (arrow), temperature was raised to 28•Ž for half of the fish of each photoperiod group (22•¨28•Ž/9L, 22•¨28•Ž/16L). For the rest of the fish, 22•Ž was continued but photo period was changed to 9L in the long photo period group (22•Ž/16•¨9L). Symbols and bars, mean•}standard errors.