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In order to assess in fish the maternal transfer of alkylphenolic compounds to the progeny, the identification and quantification of the labelled compounds present in oocytes and embryos was conducted after dietary exposure of mature female mosquitofish to 14C-4n-nonylphenol during vitellogenesis and embryogenesis respectively. Radioactivity found in bile and liver extracts accounted for 0.9-0.6 and 0.2-0.1% of ingested radioactivity for females exposed during vitellogenesis and embryogenesis respectively. The amount of extractable radioactivity present in oocytes and embryos was 0.19 and 0.07% of the ingested dose respectively. The radio-HPLC profiles obtained from bile, liver, oocyte and embryo extracts were similar. They showed the presence of 4n-NP-glucuronide as the major metabolite and traces of unchanged 4n-NP. The other metabolites corresponded to 8-hydroxynonylphenol, 9-(4-hydroxyphenyl)-nonanoic acid and para-hydroxybenzoic acid which is the final product of the alkyl chain oxidation. Our results indicate that exposure of ovoviviparous female fish to 4-NP during vitellogenesis and embryogenesis leads to the contamination of the progeny by 4-NP and its metabolites. 相似文献
53.
Geracitano LA Bocchetti R Monserrat JM Regoli F Bianchini A 《Marine environmental research》2004,58(1):1-17
Acute (4 days) and chronic (14 days) effects of copper were evaluated on the antioxidant defenses of Laeonereis acuta (Polychaeta) collected in unpolluted (UP) and polluted (P) sites. In the acute assay (125 and 250 micro g Cu/l) superoxide dismutase (SOD) and glutathione S-transferase (GST) activities did not change, whereas catalase (CAT) increased in worms from both the sites. Lipid peroxidation was higher in copper exposed worms from the P site. In the chronic assay (62.5 micro g Cu/l) polychaetes from the P site showed enhanced activities of SOD, GST and CAT and higher contents of metallothionein-like proteins and sulfhydrils compared to worms from UP. Differences in responses between polychaetes from UP and P sites suggest that organisms from the polluted site, P, are more susceptible to oxidative stress conditions. 相似文献
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在研究GPS系统的基础上建立了GPS观测数据的仿真模型,编制了相应的计算机程序。仿真模型包括卫星参数模型、动力学模型和观测误差模型。仿真计算表明,卫星参数模型和动力学模型真实地反映了卫星的运动规律;误差模型反映了观测环境对信号传播的影响。同时可以调节和选择仿真模型的参数,仿真选择了地面静态和地面低动态的观测数据,这对于论证GPS定轨、导航算法、设计GPS接收机等有一定的实用价值。 相似文献
55.
巴巴多斯和新几内亚的海平面变化表明:在过去的15000a中曾有过两次大规模的冰川融水流.同其它环境变化(如北大西洋深水环流)相比,这两次融水流形成的时间显然有助于我们进一步了解从未次冰期到问冰期的气候变迁及新仙女木事件. 相似文献
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Trends in emigration from Ireland over time are reviewed. "During the eighteenth and nineteenth centuries overseas migration to the United States and seasonal harvest migration to Britain were the main types of movement, but over the past 100 years the Irish have developed a special affinity for settling in British towns. Although the outflow was halted for a time during the 1970s, when return migration took over, the 1980s have seen a renewal of the exodus. This time, however, the character of the flow has changed from predominantly low-skill construction and factory workers to embrace better-educated emigrants, including many graduates. This shift reflects Ireland's changing position in the international market for labour." 相似文献
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