Department of Environmental Medicine, New York University School of Medicine, 57 Old Forge Road, Tuxedo, NY 10987, USA.
Aquat Toxicol. 2011 Jul;104(1-2):23-31. doi: 10.1016/j.aquatox.2011.03.009. Epub 2011 Mar 30.
The AHR pathway activates transcription of CYP1A and mediates most toxic responses from exposure to halogenated aromatic hydrocarbon contaminants such as PCBs and PCDD/Fs. Therefore, expression of CYP1A is predictive of most higher level toxic responses from these chemicals. To date, no study had developed an assay to quantify CYP1A expression in any sturgeon species. We addressed this deficiency by partially characterizing CYP1A in Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) and shortnose sturgeon (Acipenser brevirostrum) and then used derived sturgeon sequences to develop reverse transcriptase (RT)-PCR assays to quantify CYP1A mRNA expression in TCDD and PCB126 treated early life-stages of both species. Phylogenetic analysis of CYP1A, CYP1B, CYP1C and CYP3A deduced amino acid sequences from other fishes and sturgeons revealed that our putative Atlantic sturgeon and shortnose sturgeon CYP1A sequences most closely clustered with previously derived CYP1A sequences. We then used semi-quantitative and real-time RT-PCR to measure CYP1A mRNA levels in newly hatched Atlantic sturgeon and shortnose sturgeon larvae that were exposed to graded doses of waterborne PCB126 (0.01-1000 parts per billion (ppb)) and TCDD (0.001-10 ppb). We initially observed significant induction of CYP1A mRNA compared to vehicle control at the lowest doses of PCB126 and TCDD used, 0.01 ppb and 0.001 ppb, respectively. Significant induction was observed at all doses of both chemicals although lower expression was seen at the highest doses. We also compared CYP1A expression among tissues of i.p. injected shortnose sturgeon and found significant inducibility in heart, intestine, and liver, but not in blood, gill, or pectoral fin clips. For the first time, our results indicate that young life-stages of sturgeons are sensitive to AHR ligands at environmentally relevant concentrations, however, it is yet to be determined if induction of CYP1A can be used as a biomarker in environmental biomonitoring.
AHR 途径激活 CYP1A 的转录，并介导大多数因暴露于卤代芳香烃污染物（如 PCB 和 PCDD/Fs）而产生的毒性反应。因此，CYP1A 的表达可预测这些化学物质引起的大多数更高水平的毒性反应。迄今为止，尚无研究开发出用于量化任何鲟鱼物种中 CYP1A 表达的测定方法。我们通过部分表征大西洋鲟（Acipenser oxyrinchus oxyrinchus）和短吻鲟（Acipenser brevirostrum）中的 CYP1A 来解决这一不足，然后使用衍生的鲟鱼序列开发逆转录酶（RT）-PCR 测定法来量化两种物种的早期生活阶段中 TCDD 和 PCB126 处理后的 CYP1A mRNA 表达。来自其他鱼类和鲟鱼的 CYP1A、CYP1B、CYP1C 和 CYP3A 推导的氨基酸序列的系统发育分析表明，我们推测的大西洋鲟和短吻鲟 CYP1A 序列与先前推导的 CYP1A 序列最密切聚类。然后，我们使用半定量和实时 RT-PCR 测量暴露于不同浓度水相 PCB126（0.01-1000 皮克/分升（ppb））和 TCDD（0.001-10 皮克/分升）的新孵化的大西洋鲟和短吻鲟幼虫中的 CYP1A mRNA 水平。我们最初观察到与最低剂量的 PCB126 和 TCDD 相比，即 0.01 ppb 和 0.001 ppb，CYP1A mRNA 有明显的诱导。尽管在最高剂量下观察到较低的表达，但在所有两种化学物质的剂量下均观察到显著诱导。我们还比较了腹腔注射短吻鲟组织中的 CYP1A 表达，发现心脏、肠和肝脏有明显的可诱导性，但血液、鳃和胸鳍夹中没有。这是首次表明，鲟鱼的幼鱼对环境相关浓度的 AHR 配体敏感，但是，尚不确定 CYP1A 的诱导是否可以用作环境生物监测中的生物标志物。
