Min Jiho, Pham Chi Hoa, Gu Man Bock
National Research Laboratory on Environmental Biotechnology, Kwangju Institute of Science and Technology (K-JIST), 1 Oryong-dong, Puk-gu, Kwangju 500-712, South Korea.
Environ Toxicol Chem. 2003 Feb;22(2):233-8.
Five different recombinant bioluminescent strains of Escherichia coli that contain the recA (responsive to DNA damage related stress), fabA (membrane damage), katG (oxidative damage), grpE (protein damage), and lac (constitutive expression, general toxicity) promoters fused to the bacterial lux operon from either Vibrio fischeri or Photorhabdus luminescens were used to describe the different mechanisms of toxicity that several dibenzo-p-dioxins and dibenzofurans have on bacteria, as well as to determine whether bacteria can sensitively detect the presence of these compounds. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) was found to cause only DNA-related damage to bacterial cells. However, the four stress-responsive strains showed positive responses after addition of 1,2,3,4-tetrachlorodibenzo-p-dioxin (1,2,3,4-TCDD), whereas 2,3,7,8-tetrachlorodibenzo-p-furan (2,3,7,8-TCDF) caused only DNA. oxidative, and protein damage. However, 2,8-dichlorodibenzo-p-dioxin (2,8-DCDD) was not found to induce any stresses tested for in this study, that is, DNA, membrane, oxidative, and protein damage, indicating that each congener might differentially interact with the cell, stimulating differential stress responses within them. By using the constitutive strain, we found that the level of cellular toxicity experienced due to the addition of these four dioxins decreased in the order of 2,3,7,8-TCDD (the most toxic). 1,2,3,4-TCDD, 2.8-DCDD, and 2,3,7,8-TCDF. The 20% effective concentration (EC20), defined in this study the concentration of chemical that causes a 20% decrease in the bioluminescence 60 min after induction, was only 0.1 microg/L for 2,3,7,8-TCDD, a value that is lower than that of the other congeners and demonstrates that 2,3,7,8-TCDD was the most toxic compound tested in this study.
使用了五种不同的重组生物发光大肠杆菌菌株，它们包含recA（对DNA损伤相关应激有反应）、fabA（膜损伤）、katG（氧化损伤）、grpE（蛋白质损伤）和lac（组成型表达，一般毒性）启动子，这些启动子与来自费氏弧菌或发光杆菌的细菌lux操纵子融合，用于描述几种二苯并 - p - 二恶英和二苯并呋喃对细菌的不同毒性机制，以及确定细菌是否能灵敏地检测这些化合物的存在。发现2,3,7,8 - 四氯二苯并 - p - 二恶英（2,3,7,8 - TCDD）仅对细菌细胞造成与DNA相关的损伤。然而，添加1,2,3,4 - 四氯二苯并 - p - 二恶英（1,2,3,4 - TCDD）后，四种应激反应菌株显示出阳性反应，而2,3,7,8 - 四氯二苯并 - p - 呋喃（2,3,7,8 - TCDF）仅造成DNA、氧化和蛋白质损伤。然而，在本研究中未发现2,8 - 二氯二苯并 - p - 二恶英（2,8 - DCDD）诱导任何所测试的应激，即DNA、膜、氧化和蛋白质损伤，这表明每种同系物可能与细胞有不同的相互作用，从而在细胞内引发不同的应激反应。通过使用组成型菌株，我们发现添加这四种二恶英后细胞毒性水平按2,3,7,8 - TCDD（毒性最大）、1,2,3,4 - TCDD、2,8 - DCDD和2,3,7,8 - TCDF的顺序降低。本研究中定义的20%有效浓度（EC20），即诱导60分钟后导致生物发光降低20%的化学物质浓度，对于2,3,7,8 - TCDD仅为0.1微克/升，该值低于其他同系物，表明2,3,7,8 - TCDD是本研究中测试的毒性最大的化合物。
