van den Hurk Peter, Gerzel Lindsay E, Calomiris Peter, Haney Dennis C
Department of Biological Sciences, Clemson University, Clemson, SC, USA.
Biology Department, Furman University, Greenville, SC, USA.
Aquat Toxicol. 2017 Jul;188:20-25. doi: 10.1016/j.aquatox.2017.04.004. Epub 2017 Apr 13.
Observations in a previous study on biomarker responses in fish collected from urban creeks in Greenville, SC, indicated that there might be considerable differences in the expression of biotransformation enzymes in chub and sunfish species. To further investigate these species differences a dosing experiment was performed in which bluehead and creek chub (Nocomis leptocephalus and Semotilus atromaculatus), and redbreast sunfish, pumpkinseed, and bluegill (Lepomis auritus, L. gibbosus, and L. macrochirus) were injected with benzo[a]pyrene (BaP) as a model compound for common pollutants in urban creeks. Fish were injected with BaP doses of 0, 25 and 50mg/kg, and after 3days BaP metabolites in bile, and enzymatic activities of cytochrome P450-1A (CYP1A), UDP-glucuronosyltransferase (UGT) and glutathione S-transferase (GST) were measured. CYP1A activity was significantly increased after BaP dosing in both species groups, but chubs had significantly lower levels than were observed in the dosed sunfish. The UGT activity in unexposed animals was comparable in both species groups, and significantly increased in both groups as a result of BaP dosage. Finally, GST activity was significantly higher in chubs, but did not change in either species group as a result of BaP exposure. There were no significant differences between species within each species group, and the results confirmed that unexposed chubs have much lower CYP1A activity, but a much higher GST activity than unexposed sunfish. The metabolized BaP was excreted in both species groups, but at the time of sampling there were no differences in the amount of BaP metabolites in the bile of dosed animals. The differences in baseline enzyme activity and induction capacity between both species groups are an example of phylogenetically determined differences between fish families, and may explain why chubs are in general more sensitive to exposure to environmental pollutants than sunfish. This conclusion was corroborated by the observation that the highest BaP dose of 50mg/kg was close to the apparent LC for chub, while no mortality was observed in the sunfish at this dose.
先前一项关于从南卡罗来纳州格林维尔市城市小溪采集的鱼类生物标志物反应的研究观察表明，麦穗鱼和翻车鱼物种中生物转化酶的表达可能存在相当大的差异。为了进一步研究这些物种差异，进行了一项给药实验，其中将蓝头鱼和溪鲈（细头诺氏鱼和黑斑美洲鱥），以及红胸太阳鱼、圆鳍雅罗鱼和蓝鳃太阳鱼（金色小鳞太阳鱼、驼背太阳鱼和大口黑鲈）注射苯并[a]芘（BaP），作为城市小溪中常见污染物的模型化合物。给鱼注射0、25和50mg/kg剂量的BaP，3天后测量胆汁中的BaP代谢物，以及细胞色素P450-1A（CYP1A）、尿苷二磷酸葡萄糖醛酸基转移酶（UGT）和谷胱甘肽S-转移酶（GST）的酶活性。在两个物种组中，BaP给药后CYP1A活性均显著增加，但溪鲈的水平显著低于给药后的翻车鱼。未接触动物的UGT活性在两个物种组中相当，并且由于BaP给药，两组中的UGT活性均显著增加。最后，溪鲈的GST活性显著更高，但在任何一个物种组中，BaP暴露后GST活性均未改变。每个物种组内的物种之间没有显著差异，结果证实未接触的溪鲈具有比未接触的翻车鱼低得多的CYP1A活性，但GST活性高得多。两个物种组中代谢的BaP均被排泄，但在取样时，给药动物胆汁中BaP代谢物的量没有差异。两个物种组之间基线酶活性和诱导能力的差异是鱼类家族系统发育决定差异的一个例子，并且可以解释为什么溪鲈总体上比翻车鱼对环境污染物暴露更敏感。这一结论得到了以下观察结果的证实：最高BaP剂量50mg/kg接近溪鲈的表观致死浓度，而在此剂量下翻车鱼未观察到死亡。
