Effects of 2,4-dinitrotoluene exposure on enzyme activity, energy reserves and condition factors in common carp ( Cyprinus carpio)

Abstract

In this study relative condition factor (RCF) and hepatosomatic index (HSI) as well as the available energy reserves of common carp ( Cyprinus carpio) by 2,4-DNT semi-static bioassay were determined and linked to effects of enzymes in liver tissues. Fish were exposed at sublethal concentrations of 2,4-DNT (0.13 μg/L, 0.1, 0.5, 1.0 mg/L) for 7 and 15 d. Based on the results, there was no significant change in all parameters measured in fish exposed to 2,4-DNT at environmental related concentration, but 2,4-DNT stress in fish exposed to higher concentrations reflected the significant changes of physiological and biochemical responses. 2,4-DNT stress resulted in EROD activity induction in the liver, and the levels of EROD activity ranged from 0.39- to 1.83-fold higher than control. For GK, Na +/K +-ATPase, and GST, these enzyme activity continued to decline after exposure to 0.1, 0.5 and 1.0 mg/L 2,4-DNT, whereas the trend on GK and Na +/K +-ATPase was more obvious than GST. Through principal component analysis, effects by 2,4-DNT-stress in each test group were distinguished. Additionally, indications of a trade-off between metabolic cost of toxicant exposure and processes vital to the survival of the organism were seen at the enzyme activity level as well as on higher levels of biological organization.