Comparative studies on carbofuran-induced changes in some cytoplasmic and mitochondrial enzymes and proteins of epigeic, anecic and endogeic earthworms

Exposure of epigeic (Perionyx sansibaricus), anecic (Lampito mauritii) and endogeic (Metaphire posthuma) earthworms to four different concentrations (10 ppm, 20 ppm, 40 ppm and 80 ppm) of carbofuran for 16 days induced specific activities of cytoplasmic malate dehydrogenase (cMDH), mitochondrial malate dehydrogenase (mMDH) and lactate dehydrogenase (LDH). P. sansibaricus showed 33-52% increase in specific activities of aerobic (cMDH, mMDH) and anaerobic (LDH) enzymes and proteins (cytoplasmic and mitochondrial). In L. mauritii, the enhancement in enzyme and protein level was 30-46%. Similarly, M. posthuma indicated 29-43% increase in profile of enzymes and proteins. The significant increase was observed on 2nd or 3rd day and it was maximum on 16th day of carbofuran exposure. Maximum effect of carbofuran was on epigeic earthworm. The sensitivity of mitochondrial dehydrogenase and protein of different earthworm species to carbofuran appears to be associated with oxygen availability in different strata of soil habitats. Inductions in enzyme specific activity and protein content were concentration and time-dependent. The effect was more pronounced on aerobic enzymes (cMDH, mMDH) as compared to anaerobic (LDH) one. The increases in mitochondrial enzyme (47%) and protein (43%) were more than the cytoplasmic enzymes (35%) and protein (31%), which suggest a greater effect of carbofuran on respiratory metabolism of earthworms. The carbofuran-dependent increase in cytoplasmic and mitochondrial enzymes and proteins might be due to increased synthesis of metabolic enzymes and stress proteins.