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(401) Endocrine disruption and organotin compounds in abalone, Haliotis madaka and H. gigantea. Horiguchi, Toshihiro1, Cho, Hyeon-Seo2, Kojima, Mitsuhiro1, Kaya, Miyuki1, Matsuo, Taiki3, Shiraishi, Hiroaki1, Morita, Masatoshi1, Adachi, Yoshikazu3, Shimizu, Makoto4, 1 2 3 4 ABSTRACT- Histological examination of gonads as well as chemical analysis of organotin (butyltin and phenyltin) compounds in tissues of the abalone, Haliotis madaka and H. gigantea was conducted to evaluate possible endocrine disruption and to consider the causal factors for the decline of abalone stocks in Japan. Abalone specimens were monthly collected from two different areas, Tsushima as a reference site and Jogashima as a site representative of declining abalone populations. Scores were given to the development stages of reproductive cells in the ovary and testis. The degree of sexual maturation was evaluated by calculating the mean value of a histogram of these scores for the reproductive cells of each abalone. The temporal variations in degree of sexual maturation showed that female and male abalone from Tsushima matured synchronously, while those from Jogashima did not. The observed maximum reproductive developmental score in abalone from Jogashima was much lower than that from Tsushima. Approximately 20% of the abalone from Jogashima were masculinized females with an ovo-testis. The masculinization of female abalone was similar to the imposex in mesogastropods and neogastropods, induced by tributyltin (TBT) and triphenyltin (TPhT). Concentrations of TBT and TPhT in muscles of abalone from Jogashima were significantly higher than those from Tsushima. In situ exposure of abalone from Tsushima caged near a dockyard in Jogashima for 7 months resulted in spermatogenesis in the ovary of approximately 90% of females, with siginificant accumulation of TBT and TPhT. TBT and TPhT may cause spermatogenesis in female abalone. Specific distribution of butyltin and phenyltin compounds in tissues of abalone was also examined. Remarkably high concentration of TPhT was observed in head (including ganglia), while significantly high concentration of TBT was detected in ctenidium. Concentrations of butyltins and phenyltins in ovary were siginificantly higher than those in testis. The specific accumulation of TPhT as well as TBT in head (including ganglia) may suggest the disruption of neuroendocrine system, relating to the induction of endocrine disruption in abalone. Key words: endocrine disruption, abalone, tributyltin (TBT), triphenyltin (TPhT) |
