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a b s t r a c tThyroid hormones (THs) play an important role in the development and metabolism of fish through their influences on genetic transcription and are targets for endocrine disruptive agents in the aquatic environment. Amitrole is a pesticide potentially interfering with thyroid hormone regulation. In this study, the rare minnow (Gobiocypris rarus) was exposed to different levels of 3-amino-1,2,4-triazole (amitrole) and allowed to recover in clean water. Plasma TH levels and the expression of TH-related genes, including transthyretin (ttr), deiodinases (d1 and d2), and the thyroid hormone receptor (tr˛) from the livers and brains were evaluated. After exposure, the plasma TH levels did not change. Histopathological observations showed that livers were degenerated at 10,000 ng/l and these damages could be recovered by the withdrawal of amitrole. However, the ttr, d1, and d2 mRNA levels in the livers of males were significantly up-regulated in all exposure groups (p < 0.05). The ttr and d2 mRNA levels were significantly up-regulated at 10,000 ng/l and 10, 100, and 1000 ng/l in the livers of females, respectively (p < 0.05). In the brains of males, a twofold increase of d2 mRNA levels at ≥100 ng/l and a fivefold decrease of tr˛mRNA levels at ≥10 ng/l were observed (p < 0.05), whereas no significant differences were observed in the expression of d2 and tr˛in the brains of females. After a recovery period, the ttr, d1, and d2 mRNA levels in the livers of males returned to control levels, but the tr˛mRNA levels were irreversibly decreased at all treatments (p < 0.05). In addition, the d2 mRNA levels in the livers of females were significantly induced at ≥100 ng/l. Moreover, the d2 mRNA levels in the brains of males and females were up-regulated at 10,000 ng/l. These results indicated that amitrole exposure could result in alternations of ttr, d1, d2, and tr˛gene expression in different tissues of the rare minnow. The expression of these TH-related genes in males was more sensitive to amitrole than those of females. Recovery in clean water was associated with the selective regulation of TH-related gene transcription in the rare minnow. Therefore, these TH-related genes can serve as biomarkers to screen the effects of thyroid disruption chemicals in rare minnow.

Tamoxifen is widely used in the treatment of breast cancer and can enter the aquatic environment in municipal wastewater. To evaluate potential effects on embryonic development of Japanese medaka, fertilized eggs were exposed to tamoxifen at 1-625 g/l for 14 days. Adverse effects on hatchability and time to hatching only occurred at 125 and 625 g/l. Reproductive effects were assessed by exposing adults for 21 days to the same dose range. At all concentrations tested, tamoxifen significantly increased plasma vitellogenin levels in males in a dose-dependent manner. Fecundity and fertility were detrimentally affected at 625 g/l. Additionally, F1 eggs were removed from tamoxifen-contaminated water to evaluate transgenerational effects. Hatchability was affected at 625 g/l but no morphological deformities were observed. A significant dose-dependent increase in the proportion of genotypic males occurred at all concentrations greater than 5 g/l.

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and MOON, T. W. 1989. Dove reproduction and retinoid (vitamin A) dynamics in adult females and their eggs following exposure to 3,3',4,4'-tetrachlorobiphenyl. Can. J. Zool. 67:908-913. One week before mating, ring doves (Streptopelia risoria) received an intraperitoneal injection of vitamin-stripped corn oil containing 0 or 40 pglg 3,3',4,4'-tetrachlorobiphenyl. Of numerous reproductive parameters investigated, egg laying was retarded ( p < 0.001) and 43% of the embryos died primarily between days 4 and 7 of incubation in the exposed group. Exposed females laying viable eggs had higher ( p < 0.01) serum retinol at the time of mating than exposed females producing eggs that failed to develop to hatching. Serum retinol concentrations were greater ( p < 0.05) in exposed males than in control males. A method was developed to extract and quantify five naturally occumng retinoids in egg yolks. When the experiment was repeated, yolk retinol and retinyl palmitate decreased ( p < 0.05) between days 3 and 8 of development in the eggs of the exposed group regardless of embryo viability. No change in yolk retinoids occurred in the control group. At day 3 of incubation, the ratio of retinol: retinyl palmitate in yolks was greater ( p < 0.01) in the viable eggs of the exposed group than in either the controls or the nonviable eggs of the exposed group. Despite the reproductive effects, the repeated dose of biphenyl did not elicit liver porphyrin accumulation or alter internal organ weights. Liver retinol concentrations were lower in males ( p < 0.001) and females ( p < 0.05) exposed to the toxicant than in controls; liver retinyl palmitate was unchanged. These changes in retinoid dynamics during oogenesis and in ovo may be a compensatory response to the toxicant. SPEAR, P. A., BOURBONNAIS, D. H., PEAKALL, D. B., et MOON, T. W. 1989. Dove reproduction and retinoid (vitamin A) dynamics in adult females and their eggs following exposure to 3,3',4,4'-tetrachlorobiphenyl. Can. J. Zool. 67 : 908-913. Une semaine avant d'etre accouplies, des Tourterelles h collier (Streptopelia risoria) ont requ une injection intrapkritoine de 0 ou 40 pglg de 3,3',4,4'-tCtrachlorobiphCnyle. Plusieurs paramktres de la reproduction ont Ct C CtudiCs; chez les oiseaux trait&, la ponte des oeufs a CtC retardCe ( p < 0,001) et 43 % des embryons sont morts principalement entre le 4e et le 7e jours de l'incubation. Au moment de l'accouplement, les femelles traitCes dont les oeufs fkconds se sont dCveloppCs normalement ( N normaux *) avaient un taux de rktinol sCrique supCrieur ( p < 0,Ol) h celui des femelles traitCes dont les oeufs fCconds ne se sont pas dCveloppCs jusqu'h 1'Cclosion ((c anormaux B). Les concentrations de rCtinol sirique Ctaient plus ClevCes chez les miles traitCs ( p < 0,05) que chez les tCmoins. Une mCthode permettant d'extraire et de quantifier cinq ritinoi'des dans les jaunes d'oeufs a Cti mise au point. Lorsque I'expCrience a Ct C rCpCtCe, une diminution ( p < 0,05) des concentrations de rCtinol et de palmitate de rktinol a Ct C enregi...

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Persistent organochlorine pesticides pollutants (OCPs) have been reported to occur at relatively high concentrations in some Chinese waters. In order to map the distribution of organochlorine pesticides in the surface water throughout China, samples were collected from over 600 sites in seven major river basins and three main internal rivers drainage areas during 2003 and 2004. The surface water samples were analyzed for the representative organochlorine pesticides contaminants including lindane (gamma-HCH), p,p'-DDT and heptachlor epoxide. In general, the most frequently detected compound was lindane, being detected in 83.9% of samples (mean=31.3 ng/l; range <0.17-860 ng/l), and the highest concentration was present in the Yellow River basin. p,p'-DDT was detected in 63.1% of the samples collected (mean=14.6 ng/l; range <0.14-368 ng/l) with the highest concentration present in the Huaihe River basin. Heptachlor epoxide was detected in only 9.3% of water samples (range <0.11-10 ng/l). Measured concentrations for the three compounds were low and rarely exceed the environment quality standard for surface water of China. Lindane was more frequently detected at much higher concentrations in the rivers of northern China compared with those of southern China. The sites with higher concentration of lindane and p,p'-DDT mainly occurred in the Yellow River and Huaihe River basins, so the results of this investigation indicate that the organochlorine pesticide contamination of Yellow River and Huaihe River basins should be of particular concern relative to the other basins. When compared with other regions of the world, it appears that the Chinese surface water is moderately polluted by lindane and p,p'-DDT.