Activation of a stress-induced gene by insecticides in the midge, Chironomus yoshimatsui

Stress proteins (heat shock proteins, HSPs) have been proposed as general biomarkers for environmental monitoring. In the present study, we evaluated the environmental stress‐burden on the aquatic midge Chironomus yoshimatsui using hsp70 expression. Larvae collected from streams receiving polluted r...

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Published in:	Journal of biochemical and molecular toxicology Vol. 16; no. 1; pp. 10 - 17
Main Authors:	Yoshimi, Tatsuya, Minowa, Kozue, Karouna-Renier, Natalie K., Watanabe, Chiharu, Sugaya, Yoshio, Miura, Takashi
Format:	Journal Article
Language:	English
Published:	New York Wiley Subscription Services, Inc., A Wiley Company 01-01-2002
Subjects:	Amino Acid Sequence Animals Carbamates - toxicity Chironomidae - drug effects Chironomidae - genetics Chironomus Environmental Monitoring Fenitrothion - toxicity Gene Expression Regulation HSP70 HSP70 Heat-Shock Proteins - genetics Insecticide Insecticides - toxicity Larva - drug effects Larva - genetics Lethal Dose 50 Molecular Sequence Data Phenylcarbamates Pyrethrins - toxicity Reverse Transcriptase Polymerase Chain Reaction RNA, Messenger - analysis Time Factors
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Summary:	Stress proteins (heat shock proteins, HSPs) have been proposed as general biomarkers for environmental monitoring. In the present study, we evaluated the environmental stress‐burden on the aquatic midge Chironomus yoshimatsui using hsp70 expression. Larvae collected from streams receiving polluted runoff (field strain) were resistant to the organophosphorus insecticide, fenitrothion (F), and the synthetic pyrethroid, ethofenprox (E), whereas a strain originally collected from an unpolluted area (susceptible strain) showed low resistance to insecticide exposure. To examine the expression of an HSP70 gene in C. yoshimatsui, an hsp70 cDNA probe was prepared using RNA obtained from the field strain larvae and used for Northern blot analyses. The expression of this HSP70 gene in larvae collected from two field sites in May about 1 week after insecticide spraying in the fields was 2.3 (p = 0.018) to 3.3 fold higher than that in the susceptible strain and was also 4.6 and 1.4 (p = 0.033) fold higher than those collected in November 3 months after the cessation of insecticide spraying. In order to identify potential inducers of the HSP70 gene of the field strain, larvae of the susceptible strain were exposed to F or E for 24 h and hsp70 mRNA levels determined. Exposures to F at 0.4 μg/L and E at 1.1 μg/L increased hsp70 mRNA levels 2.7 (p = 0.049) and 4.4 (p = 0.043) fold over controls, respectively. These results suggest that larvae collected from polluted areas are burdened by environmental stressors and the tested insecticides are potential inducers of HSP70. The results also support the suggestion that HSP70 gene expression is a sensitive indicator of low level (nonlethal) exposures to certain insecticides. © 2002 Wiley Periodicals, Inc. J Biochem Mol Toxicol 16:10–17, 2002; DOI 10.1002/jbt.10018
Bibliography:	Ministry of Education, Science and Culture, Japan - No. 08878080 and 13680633 ArticleID:JBT10018 istex:B16B71E343A089AB7DC235E65B3DE83305EF19A9 ark:/67375/WNG-RZ9385K1-F
ISSN:	1095-6670 1099-0461
DOI:	10.1002/jbt.10018