Department of Biology, University of Kentucky, Lexington, KY 40506, USA.
Comp Biochem Physiol C Toxicol Pharmacol. 2010 Jun;152(1):42-50. doi: 10.1016/j.cbpc.2010.02.008. Epub 2010 Feb 20.
Although Lepomis species are abundant in a wide variety of habitats throughout North America and could serve as potentially valuable biomonitoring tools, few studies have examined the induction of pollutant biomarkers in this genus. We hypothesized that the induction of cytochrome P-450 1A (CYP1A), a sensitive and widely used indicator of response to aquatic contaminants, would serve as an effective biomarker of organic pollutant exposure in Lepomis species. We examined the response of CYP1A and two of the major pollutant-responsive phase II enzymes, glutathione S-transferase (GST), and uridine diphosphate glucuronyltransferase (UDPGT), in Lepomis exposed to organic pollutants under laboratory and field conditions. Two Lepomis species (longear sunfish, Lepomis megalottis and bluegill, Lepomis macrochirus) were exposed in the laboratory via intraperitoneal injection to corn oil (vehicle), benzo(a)pyrene (BaP) (10 and 50mg/kg), a polynuclear aromatic hydrocarbon (PAH) or 3,4,3',4'-tetrachlorobiphenyl (PCB 77) (0.1 and 1.0mg/kg), a dioxin-like planar halogenated aromatic hydrocarbon (HAH), and sacrificed 2 (BaP) or 7 (corn oil, PCB77) days later. Lepomis hepatic CYP1A exhibited differential sensitivity to these two classes of environmental contaminants. CYP1A activity was weakly induced in bluegill exposed to 1.0mg/kg PCB 77 (3 fold induction over controls) but strongly induced in both bluegill and longear sunfish exposed to 50mg/kg BaP (37 and 15 fold induction over controls, respectively). In contrast, hepatic GST activity in both species remained unchanged following the treatment with either compound and hepatic UDPGT activity, which was assessed only in BaP-treated longear sunfish, was unaffected by that chemical, indicating these phase II enzymes may not be sensitive pollutant biomarkers in this genus. Further, longear sunfish collected from a PCB contaminated site displayed relatively low levels of CYP1A activity despite PCB body burdens associated with strong induction of CYP1A activity in other fish species. The strong induction of CYP1A by BaP with much weaker CYP1A response to PCB indicates that CYP1A in Lepomis sp. could be an excellent biomarker for PAH pollution, but may not be a reliable indicator of site contamination by halogenated hydrocarbons. We conclude that Lepomis species provide a useful model for examining the regulation and potential consequences of differential pollutant sensitivity, but that CYP1A in these species should be used with caution as an indicator of halogenated contaminants.
尽管 Lepomis 物种在北美的各种栖息地中大量存在，并且可以作为潜在有价值的生物监测工具，但很少有研究检查过该属中污染物生物标志物的诱导。我们假设细胞色素 P-450 1A（CYP1A）的诱导，这是一种对水生污染物反应的敏感且广泛使用的指标，将作为 Lepomis 物种暴露于有机污染物的有效生物标志物。我们检查了在实验室和野外条件下，暴露于有机污染物的 Lepomis 物种中 CYP1A 和两种主要的污染物响应的 II 期酶，谷胱甘肽 S-转移酶（GST）和尿苷二磷酸葡萄糖醛酸转移酶（UDPGT）的反应。两种 Lepomis 物种（大眼太阳鱼，Lepomis megalottis 和蓝鳃太阳鱼，Lepomis macrochirus）通过腹膜内注射玉米油（载体），苯并（a）芘（BaP）（10 和 50mg/kg），多环芳烃（PAH）或 3,4,3',4'-四氯联苯（PCB 77）（0.1 和 1.0mg/kg），二恶英样平面卤代芳烃（HAH），并在 2（BaP）或 7（玉米油，PCB77）天后牺牲。Lepomis 肝 CYP1A 对这两类环境污染物表现出不同的敏感性。暴露于 1.0mg/kg PCB 77 的蓝鳃太阳鱼中的 CYP1A 活性较弱（比对照组诱导 3 倍），但暴露于 50mg/kg BaP 的蓝鳃太阳鱼和大眼太阳鱼中的 CYP1A 活性强烈诱导（分别比对照组诱导 37 和 15 倍）。相比之下，两种物种的肝 GST 活性在接受任何一种化合物处理后均保持不变，而仅在 BaP 处理的大眼太阳鱼中评估的肝 UDPGT 活性不受该化学物质的影响，表明这些 II 期酶可能不是该属的敏感污染物生物标志物。此外，尽管与其他鱼类物种中 CYP1A 活性的强烈诱导相关联，但从 PCB 污染的地点收集的大眼太阳鱼的 CYP1A 活性水平相对较低。BaP 对 CYP1A 的强烈诱导与 PCB 对 CYP1A 反应的弱诱导表明，Lepomis sp.中的 CYP1A 可能是 PAH 污染的极好生物标志物，但可能不是卤代烃污染地点的可靠指标。我们的结论是，Lepomis 物种为检查污染物敏感性的调节和潜在后果提供了有用的模型，但这些物种中的 CYP1A 作为卤代污染物的指标应谨慎使用。
