Biological and molecular responses of Chironomus riparius (Diptera, Chironomidae) to herbicide 2,4-D (2,4-dichlorophenoxyacetic acid).
2,4-Dichlorophenoxyacetic acid (2,4-D) is an agricultural contaminant found in rural ground water. It remains to be determined whether neither 2,4-D poses environmental risks, nor is the mechanism of toxicity known at the molecular level. To evaluate the potential ecological risk of 2,4-D, we assessed the biological parameters including the survival rate, adult sex ratio of emerged adults, and mouthpart deformities in Chironomus riparius after long-term exposure to 2,4-D. The larvae were treated with 0.1, 1 or, 10microgL(-1) of 2,4-D for short- and long-term exposure periods. The sex ratio was changed in C. riparius exposed to only 10microgL(-1) of 2,4-D, whereas mouthpart deformities were observed as significantly higher in C. riparius exposed to 0.1microgL(-1) of 2,4-D. Survival rates were not significantly affected by 2,4-D. Furthermore, we evaluated the molecular and biochemical responses of biomarker genes such as gene expression of heat shock proteins (HSPs), ferritins and glutathione S-transferases (GSTs) in C. riparius exposed to 2,4-D for 24h. The expressions of HSP70, HSP40, HSP90 and GST levels in C. riparius were significantly increased after exposure to a 10microgL(-1) concentration of 2,4-D, whereas ferritin heavy and light chain gene expressions were significantly increased at all concentrations of 2,4-D exposure. Finally, these results may provide an important contribution to our understanding of the toxicology of 2,4-D herbicide in C. riparius. Moreover, the 2,4-D-mediated gene expressions may be generated by 2,4-D is the causative effects on most probable cause of the observed alterations. These biological, molecular and morphological parameters and the measured parameters can be used to monitor 2,4-D toxicity in an aquatic environment.
Department of Fisheries and Ocean Science, Chonnam National University, San 96-1, Dundeok-dong, Yeosu, Jeonnam 550-749, Republic of Korea.
Kiyun
K
Park
Jungan
J
Park
Jongkyu
J
Kim
Inn-Sil
IS
Kwak
D015084:2,4-Dichlorophenoxyacetic Acid / Q000633:toxicity*; D000818:Animals; D002683:Chironomidae / Q000187:drug effects*; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods; D005260:Female; D005293:Ferritins / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects*; D020869:Gene Expression Profiling; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D006540:Herbicides / Q000633:toxicity*; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism; D007814:Larva / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D008136:Longevity / Q000187:drug effects; D008297:Male; D009055:Mouth / Q000187:drug effects / Q000254:growth & development; D012744:Sex Ratio; D014874:Water Pollutants, Chemical / Q000633:toxicity*
D006360:Heat-Shock Proteins; D006540:Herbicides; D019476:Insect Proteins; D014874:Water Pollutants, Chemical; D015084:2,4-Dichlorophenoxyacetic Acid; D005293:Ferritins