Chemical-induced alteration of hemoglobin expression in the 4th instar larvae of Chironomus tentans Mg. (Diptera: Chironomidae)

In this study, a preliminary characterization of the multiplicity of Chironomus hemoglobin (Hb) was conducted on the larvae of Chironomus tentans Mg. (Diptera: Chironomidae) by the molecular mass and isoelectric point. In order to identify Chironomus Hb as potential biomarker of environmental contamination, alteration of individual Hb by exposure to environmental chemicals, namely, nonylphenol, benzo[a]pyrene, chloropyriphos and cadmium chloride, were evaluated. To validate the ecotoxicological relevance of Chironomus Hb as a potential biomarker, ecotoxicity test using growth rate as toxic endpoint was also conducted. This study revealed a striking heterogeneity in C. tentans Hb; 10 Hb isoforms were observed in the larvae of 4th instar C. tentans by their molecular mass and by their isoelectric point. Chemical-induced alteration of individual Hb expression suggests that C. tentans Hb can be a target molecule for chemical exposure. Overall results suggest that the expression pattern of Hb proteins may potentially contribute to the development of a biomarker for ecotoxicity monitoring in C. tentans.