Parente Thiago E M, De-Oliveira Ana C A X, Silva Igor B, Araujo Francisco G, Paumgartten Francisco J R
Laboratory of Environmental Toxicology, Department of Biological Sciences, National School of Public Health, Oswaldo Cruz Foundation (FIOCRUZ), Av. Brasil 4325, Rio de Janeiro RJ 21045-900, Brazil.
Chemosphere. 2004 Mar;54(11):1613-8. doi: 10.1016/j.chemosphere.2003.09.027.
The activity of fish monooxygenases has been extensively used as a monitoring tool to detect contamination of water bodies by cytochrome P450-inducing agents. In this study we evaluated the activities of ethoxy- (EROD), methoxy- (MROD) and pentoxy- (PROD) resorufin-O-dealkylases in the liver of Nile tilapias (Oreochromis niloticus) collected at the Guandu river, at a reference clean site (Lake 1) and at two other sampling sites (Lakes 2 and 3) in Rio de Janeiro state, Brazil. Alkoxyresorufin-O-dealkylases were measured fluorimetrically in the hepatic S9 fraction. EROD (17.7-fold), MROD (14.2-fold) as well as PROD activities were considerably higher in tilapias from Guandu river. A moderate increase of EROD (5.0-fold) and MROD (5.4-fold) was also found in tilapias from Lake 3. These findings suggest that Guandu river watershed, the main source of urban drinking water supply in Rio de Janeiro, is polluted with CYP1A-inducing xenobiotics. Furthermore, we also found a good linear relationship between EROD and MROD, a finding that agrees with the hypothesis that the two reactions are catalysed by the same CYP1A isoform in O. niloticus.
鱼类单加氧酶的活性已被广泛用作监测工具，以检测细胞色素P450诱导剂对水体的污染。在本研究中，我们评估了在巴西里约热内卢州的关杜河、一个参考清洁地点（1号湖）以及另外两个采样地点（2号湖和3号湖）采集的尼罗罗非鱼（Oreochromis niloticus）肝脏中乙氧基-（EROD）、甲氧基-（MROD）和戊氧基-（PROD）试卤灵-O-脱烷基酶的活性。通过荧光法测定肝脏S9组分中的烷氧基试卤灵-O-脱烷基酶。来自关杜河的罗非鱼中，EROD（17.7倍）、MROD（14.2倍）以及PROD活性显著更高。在3号湖的罗非鱼中也发现EROD（5.0倍）和MROD（5.4倍）有适度增加。这些发现表明，里约热内卢城市饮用水的主要水源——关杜河流域受到了诱导CYP1A的外源性物质的污染。此外，我们还发现EROD和MROD之间存在良好的线性关系，这一发现与两种反应由尼罗罗非鱼中相同的CYP1A同工型催化的假设相符。
