Grupo de Biología y Toxicología Ambiental, Facultad de Ciencias, Universidad Nacional de Educación a Distancia, UNED, Senda del Rey 9, 28040 Madrid, Spain.
Comp Biochem Physiol C Toxicol Pharmacol. 2012 Mar;155(2):333-43. doi: 10.1016/j.cbpc.2011.10.001. Epub 2011 Oct 12.
Cytochrome P450 family members participate in xenobiotic transformation as a detoxification mechanism. We have characterized a CYP gene, assigned to the 4G family, in Chironomus riparius, a reference organism in aquatic toxicology. Due to the potential interest of CYP genes and P450 proteins for monitoring pollution effects at the molecular level, the alterations in the pattern of expression of this gene, induced by different xenobiotics, were analyzed. Different compounds, such as the biocide tributyltin (TBTO) and two other well-known endocrine disruptors, nonylphenol (NP) and bisphenol A (BPA), were tested at different concentrations and acute exposures. Upregulation of the CrCYP4G gene was found after exposures to TBTO (1 ng/L 24h-0.1 ng/L 96 h) and, as measured by RT-PCR mRNA quantification, its level was up to twofold that of controls. However, in contrast, NP (1, 10, 100 μg/L, 24h) and BPA (0.5mg/L 24h-3mg/L 96 h) downregulated the gene (by around a half of the control level) suggesting that this gene responds specifically to particular chemicals in the environment. Glutathione-S-transferase (GST) enzymatic activity was also evaluated for each condition. A fairly good correlation was found with CYP4G gene behavior, as it was activated by TBTO (96 h), but inhibited by NP and BPA (24h). Only the higher concentration of BPA tested activated GST, whereas it inhibited CYP4G activity. The results show that different xenobiotics can induce distinct responses in the detoxification pathway, suggesting multiple xenobiotic transduction mechanisms. This work confirms that specific P450 codifying genes, as well as GST enzyme activities, could be suitable biomarkers for ecotoxicological studies.
细胞色素 P450 家族成员作为解毒机制参与外来化合物的转化。我们已经鉴定了摇蚊（Chironomus riparius）中的一个 CYP 基因，该基因属于 4G 家族，摇蚊是水生毒理学的参考生物。由于 CYP 基因和 P450 蛋白在分子水平上监测污染影响的潜在兴趣，因此分析了该基因在外来化合物诱导下表达模式的变化。不同的化合物，如杀生物剂三丁基锡（TBTO）和另外两种已知的内分泌干扰物壬基酚（NP）和双酚 A（BPA），在不同浓度和急性暴露下进行了测试。暴露于 TBTO（1ng/L 24h-0.1ng/L 96h）后，发现 CrCYP4G 基因上调，通过 RT-PCR mRNA 定量测量，其水平是对照的两倍。然而，相反，NP（1、10、100μg/L，24h）和 BPA（0.5mg/L 24h-3mg/L 96h）下调了该基因（约为对照水平的一半），表明该基因对环境中的特定化学物质有特异性反应。还评估了每种条件下的谷胱甘肽-S-转移酶（GST）酶活性。发现它与 CYP4G 基因行为具有相当好的相关性，因为它被 TBTO（96h）激活，但被 NP 和 BPA（24h）抑制。只有测试的较高浓度的 BPA 激活了 GST，而抑制了 CYP4G 活性。结果表明，不同的外来化合物可以在解毒途径中诱导不同的反应，表明存在多种外来化合物转导机制。这项工作证实，特定的 P450 编码基因以及 GST 酶活性可以作为生态毒理学研究的合适生物标志物。
