title: Regulation of lead toxicity by heat shock protein 90 (daf-21) is affected by temperature in Caenorhabditis elegans.
abstract: In the nematode Caenorhabditis elegans, stress resistance can be regulated by dauer formation (daf) genes. In the present study, regulation of heavy metal lead (Pb) toxicity by the 90-kDa heat shock proteins (Hsp90; daf-21) was investigated in both wild-type C. elegans and daf-21/Hsp90 mutants by focusing on the effects of varied temperatures below (15°C) or above (25 and 30°C) the presumptive optimum growth temperature (20°C). More acute toxicity of Pb, indicated by the 24-h median lethal concentrations (LC50), was observed in wild-type adults than in the daf-21 mutant adults at 15, 20 and 25°C; however, the daf-21 mutant adults showed more sensitivity at 30°C. Enhanced Pb sensitivity (e.g., decrease LC50) in both types of C. elegans was observed with both increased and decreased temperatures when compared to that at 20°C. Additional examined endpoints included time course of toxicity at LC50s, pharyngeal pumping, reproduction, life span, and Hsp90 expression. Collective results showed that temperatures both above and below 20°C exacerbated Pb toxicity, and that the protein level of daf-21/Hsp90 was one of the most sensitive indicators of Pb toxicity in wild-type C. elegans, while pharyngeal pumping was more Pb sensitive in daf-21 mutants. Therefore, the expression of daf-21/Hsp90 has apparent utility for the prediction and assessment of Pb-induced toxicity in nematodes. Further, the stress responses related to Hsp90 expression in C. elegans may have considerable potential as sensitive biomarkers for the monitoring of environmental Pb contamination.
authors.affiliation: Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China; Department of Veterinary Biosciences and Diagnostic Imaging, College of Veterinary Medicine, University of Georgia, Athens, GA 30602-7382, USA.
authors.forename: Yunbiao
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Neurosurgery, First Hospital, Jilin University, Changchun 130021, China.
authors.forename: Songbai
authors.initials: S
authors.lastname: Xu
authors.affiliation: Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.affiliation: Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China.
authors.forename: Yanhui
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Veterinary Biosciences and Diagnostic Imaging, College of Veterinary Medicine, University of Georgia, Athens, GA 30602-7382, USA. Electronic address: tlguo1@uga.edu.
authors.forename: Tai L
authors.initials: TL
authors.lastname: Guo
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism*; D004785:Environmental Pollutants / Q000633:toxicity; D005786:Gene Expression Regulation / Q000187:drug effects; D018841:HSP90 Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism*; D007854:Lead / Q000633:toxicity*; D007928:Lethal Dose 50; D012098:Reproduction / Q000187:drug effects; D013696:Temperature
chemical_list: D029742:Caenorhabditis elegans Proteins; D004785:Environmental Pollutants; D018841:HSP90 Heat-Shock Proteins; D007854:Lead
keywords: Caenorhabditis elegans; Heat shock protein 90; Heavy metal lead; Temperature