Response of phase I and II detoxification enzymes, glutathione, metallothionein and acetylcholine esterase to mercury and dimethoate in signal crayfish (Pacifastacus leniusculus)

Abstract

Metals and pesticides are common pollutants and the modulation of biomarkers can indicate sub-lethal influences on the physiology of organisms inhabiting impacted aquatic systems. We examined the effects of mercury and the organophosphate pesticide dimethoate on EROD, MROD, glutathione S-transferase (GST), acetylcholine esterase (AChE), metallothionein (MT) and glutathione (GSH) in the signal crayfish (Pacifastacus leniusculus). Crayfish were injected with mercury chloride or dimethoate (0.3, 0.6, 0.9 μg kg) and dissected after 72 h. EROD activity in the hepatopancreas did not change in response to mercury chloride treatment but exhibited a dose dependent decrease at all concentrations of dimethoate tested. MROD (hepatopancreas) exhibited a significant decrease at the 0.9 μg kg treatment for both chemicals. GST (hepatopancreas) demonstrated a significant dose dependent decrease at all concentrations of both mercury chloride and dimethoate. AChE (tail muscle) decreased at the 0.6 and 0.9 μg kg concentrations of dimethoate and 0.9 μg kg mercury chloride. In gill tissue, MT increased in response to 0.3 and 0.6 μg kg of mercury chloride but no effect was observed at the 0.9 μg kg concentration of mercury chloride or any concentrations of dimethoate tested. MT did not change in response to mercury or dimethoate in tail tissue. Furthermore, neither chemical modulated GSH concentrations. Our results indicate that, apart from GSH, these markers are sensitive to the pollutants tested and that animals exposed in the wild are potentially compromised in their ability to detoxify environmental contaminants and carry out normal cellular processes.

Inhibitory effect of metals on animal and plant glutathione transferases

“…The fail of fully reactivation by GSH pointed to inhibition mechanisms other than simple binding to SH-groups by toxic metals. In a recent study of Gunderson et al [83] in the signal crayfish Pacifastacus leniusculus a similar decrease of the GST activity in hepatopancreas cytosol was observed under Hg 2+ exposition at concentrations comparable to previous studies.…”

The Associated Regulatory Mechanisms of Zinc Lactate in Redox Balance and Mitochondrial Function of Intestinal Porcine Epithelial Cells

“…MT participates in the storage, transport, and bioutilization of Zn, so a decreased expression of MT reduces the absorption efficiency of Zn in the body [ 36 ]. Moreover, MT2 is rich in reduced thiol groups (SH), which have a free radical scavenging capacity 100 times that of GSH, and can inhibit the release of mitochondrial cytochrome c and activate caspase-3 to reduce cell apoptosis and myocardial injury [ 37 , 38 ]. These were further confirmed by the present study where it was found that ZnLA administration increased the mRNA expression of ZNT-1, MT1A, and MT-2B and intracellular GSH-PX activity, but decreased LDH activity, cell apoptosis, and caspase-3 protein expression levels in IPEC-J2 cells.…”

Essential Oils Extracted from Different Species of the Lamiaceae Plant Family as Prospective Bioagents against Several Detrimental Pests

“…Detoxifying enzymes such as esterase and glutathione S-transferases have a significant effect on pest resistance before pesticides. Consequently, impairing the function of such enzymes can reduce the likelihood of pest resistance to essential oils [114]. Furthermore, histological changes in the epithelial cells of insects' midguts [115], and even a diminution in the respiration rate of pests have also been reported [116].…”