PARENT SESSION
PM4 - Complex Mixtures
Monday, 18 November 2002
8:00 AM to 6:30 PM
Exhibit Hall
(P246) Effects of mixtures of tributyltin and polychlorinated biphenyls on reproduction in Japanese medaka (Oryzias latipes), part II: Transgenerational toxicity.
Nakayama, Kei*,1, Oshima, Yuji1, Nagafuchi, Ken1, Hano, Takeshi1, Shimasaki, Yohei1, Honjo, Tsuneo1, 1 Laboratory of Fisheries Environmental Science, Graduate School, Kyushu University, Fukuoka, Japan
ABSTRACT- The transgenerational toxicities of tributyltin (TBT), polychlorinated biphenyls (PCBs; Kanechlor-400), and mixtures of both chemicals were examined. Forty-eight pairs of FLF-II strain medaka were prepared and the pairs were divided into 8 groups. For 21 days, each group of medaka was administered freeze-dried brine shrimp flakes contaminated with a mixture of 0, 1, 5, or 25 
g TBT/g plus 0 or 25 g PCBs/g. The embryos spawned in last 3 days of the administration period were cultured with an embryo-rearing media at 27 °C. Development, normal hatching success, time to hatching, and swim-up failure were assessed. The newly hatched larvae were placed in 2.5-L glass chambers, and we measured survival at 10 days post hatch (dph). The juveniles were maintained until maturation, and then phenotypic and genetic sex were examined. Abnormal development of the eyes, i.e., small eyes or no eyes, was observed in all treatment groups except for the 1-g TBT/g group, while no developmental abnormalities were observed in the control group. Administration of TBT significantly decreased normal hatching success and increased swim-up failure, and administration of PCBs significantly increased the time to hatching. Furthermore, analysis by 2-way ANOVA detected an interaction between TBT and PCBs in normal hatching success, swim-up failure, and the time to hatching. Survival at 10 dph was not affected in any treatment group. These results indicated that TBT induced abnormal development of the medaka embryos, and PCBs delayed the time to hatching. Moreover, development of embryos was potentially more affected by the mixtures of TBT and PCBs than by the individual chemicals. The results of sex ratio analyses will be presented.
Key words: TBT, PCBs, Medaka, Transgenerational Toxicity