Effects of the herbicide isoproturon on metallothioneins, growth, and antioxidative defenses in the aquatic worm Tubifex tubifex (Oligochaeta, Tubificidae).
Metallothioneins (MTs) are low molecular weight proteins, mainly implicated in metal ion detoxification. Increase in MT contents is considered to be a specific biomarker of metal exposure. Recently it has been demonstrated that MTs participate in several cellular functions such as regulation of growth, and antioxidative defenses. Therefore, the induction of MTs as biomarkers of exposure to the pesticide isoproturon has been investigated in the aquatic worms Tubifex tubifex. MT levels in exposed worms increased significantly (p < 0.05) after 2, 4, and 7 days of exposure to different concentrations of isoproturon (maximum increase compared to unexposed controls: +148.56% for 10 mg l(-1) after 4 days of exposure). In response to isoproturon, the activity of glutathione-S-transferase (max. +52%), glutathione-reductase (max. +100%), and catalase (max. +117%) increased, demonstrating the occurrence of an oxidative stress response to the herbicide. Thus, the increase in MT contents caused by isoproturon was interpreted as a defense response towards increased oxidative stress generated by the herbicide. Residues of isoproturon and its metabolites, 1-(4-isopropylphenyl)-3-methylurea, 1-(4-isopropylphenyl) urea, and 4-isopropylanilin were detected in the worm growth medium. Half-life of the herbicide was shorter at a low (0.1 mg l(-1)) initial concentration. The herbicide accumulated in T. tubifex but no metabolite could be detected.
Mosleh
Yahia Y
YY
Laboratoire d'Eco-Toxicologie, Unité de Recherche sur la Vigne et le Vin de Champagne, EA 2069 Faculté des Sciences, Université de Reims Champagne-Ardenne, B.P. 1039, Reims cedex 02, 51687 France.
Paris-Palacios
Séverine
S
Couderchet
Michel
M
Biagianti-Risbourg
Sylvie
S
Vernet
Guy
G
D000818:Animals; D015415:Biomarkers / Q000032:analysis; D006540:Herbicides / Q000493:pharmacokinetics / Q000633:toxicity*; D008668:Metallothionein / Q000032:analysis / Q000187:drug effects* / Q000378:metabolism; D009835:Oligochaeta / Q000254:growth & development* / Q000502:physiology; D018384:Oxidative Stress; D010671:Phenylurea Compounds / Q000493:pharmacokinetics / Q000633:toxicity*; D014018:Tissue Distribution
D015415:Biomarkers; D006540:Herbicides; D010671:Phenylurea Compounds; C028904:isoproturon; D008668:Metallothionein