Environmentally induced oxidative stress in aquatic animals

Free radicals, reactive oxygen species, oxidative stress and its classification

Glutathione (GSH) is a tripeptide, which has many biological roles including protection against reactive oxygen and nitrogen species. The primary goal of this paper is to characterize the principal mechanisms of the protective role of GSH against reactive species and electrophiles. The ancillary goals are to provide up-to-date knowledge of GSH biosynthesis, hydrolysis, and utilization; intracellular compartmentalization and interorgan transfer; elimination of endogenously produced toxicants; involvement in metal homeostasis; glutathione-related enzymes and their regulation; glutathionylation of sulfhydryls. Individual sections are devoted to the relationships between GSH homeostasis and pathologies as well as to developed research tools and pharmacological approaches to manipulating GSH levels. Special attention is paid to compounds mainly of a natural origin (phytochemicals) which affect GSH-related processes. The paper provides starting points for development of novel tools and provides a hypothesis for investigation of the physiology and biochemistry of glutathione with a focus on human and animal health.

https://downloads.hindawi.com/archive/2012/736837.pdf

Glutathione Homeostasis and Functions: Potential Targets forMedical Interventions

Chromium exists in oxidation states ranging from −IV to +VI, inclusively. The compounds exhibit a wide range of geometries including square planar, tetrahedral, octahedral, and various distorted geometries. Ore refining, chemical and refractory processing, cement-producing plants, automobile brake lining, catalytic converters for automobiles, leather tanneries, and chrome pigments contribute to the atmospheric burden of chromium. Hexavalent chromium is known to have 100-fold more toxicity than trivalent chromium, for both acute and chronic exposures because of its high water solubility and mobility, as well as easy reduction. The respiratory tract is the major target organ for hexavalent chromium following the inhalation exposure in humans. Chronic inhalation exposure to hexavalent chromium results in effects on the respiratory tract, with perforations and ulcerations of the septum, bronchitis, decreased pulmonary function, pneumonia, and nasal itching and soreness as reported. Chronic human exposure to h...

Sources and toxicity of hexavalent chromium

Glyphosate [N-(phosphonomethyl) glycine] is a broad spectrum, post emergent herbicide and is among the most widely used agricultural chemicals globally. Initially developed to control the growth of weed species in agriculture, this herbicide also plays an important role in both modern silviculture and domestic weed control. The creation of glyphosate tolerant crop species has significantly increased the demand and use of this herbicide and has also increased the risk of exposure to non-target species. Commercially available glyphosate-based herbicides are comprised of multiple, often proprietary, constituents, each with a unique level of toxicity. Surfactants used to increase herbicide efficacy have been identified in some studies as the chemicals responsible for toxicity of glyphosate-based herbicides to non-target species, yet they are often difficult to chemically identify. Most glyphosate-based herbicides are not approved for use in the aquatic environment; however, measurable quantities of the active ingredient and surfactants are detected in surface waters, giving them the potential to alter the physiology of aquatic organisms. Acute toxicity is highly species dependant across all taxa, with toxicity depending on the timing, magnitude, and route of exposure. The toxicity of glyphosate to amphibians has been a major focus of recent research, which has suggested increased sensitivity compared with other vertebrates due to their life history traits and reliance on both the aquatic and terrestrial environments. This review is designed to update previous reviews of glyphosate-based herbicide toxicity, with a focus on recent studies of the aquatic toxicity of this class of chemicals.

Impact of glyphosate and glyphosate‐based herbicides on the freshwater environment

Low toxic herbicide Roundup induces mild oxidative stress in goldfish tissues.

Chromium(III) induces oxidative stress in goldfish liver and kidney.

The effect of potassium dichromate on free radical processes in goldfish: Possible protective role of glutathione

Cytotoxicity of chromium ions may be connected with induction of oxidative stress

The present study directly compared the effects of exposure to Cr6+ and Cr3+ (10 mg/L) over 24, 48 and 96 h on indices of oxidative stress and activities of antioxidant and related enzymes in goldfish brain, liver, kidney and gills. Glutathione status clearly demonstrated the development of oxidative stress, whereas changes in protein carbonyls and lipid peroxides were less pronounced. The activity of superoxide dismutase (SOD) was virtually unaffected after 24 or 96 h exposure, but 48 h exposure to Cr6+ reduced SOD activity in brain (by 30%), enhanced activity in kidney (by 28%) and had no effect on liver SOD. Chromium exposure for shorter times had no effect on catalase activity, whereas 96 h exposure depressed activity in liver, kidney and gills. Exposure to Cr6+ reduced catalase activity in liver by 53% and in kidney by 21%, while in gills it was reduced by 20 and 38% by exposure to Cr3+ and Cr6+, respectively. Exposure to chromium for 24 h did not affect glutathione-S-transferase activity, but treatment with Cr6+ for 48 h enhanced it in brain by 1.5-fold, whereas exposure to Cr3+ decreased activity by 29% in kidney. Fish treatment with chromium ions for 96 h decreased glutathione-S-transferase activity in liver by 51 and 25%, respectively. Chromium exposure had very little effect on the activities of GR or G6PDH. These data show that both chromium ions induced oxidative stress in goldfish tissues and affected the activity of antioxidant and associated enzymes.

Chromium effects on free radical processes in goldfish tissues: comparison of Cr(III) and Cr(VI) exposures on oxidative stress markers, glutathione status and antioxidant enzymes.

Olha I. Kubrak

Papers

Low toxic herbicide Roundup induces mild oxidative stress in goldfish tissues.

Chromium(III) induces oxidative stress in goldfish liver and kidney.

The effect of potassium dichromate on free radical processes in goldfish: Possible protective role of glutathione

Cytotoxicity of chromium ions may be connected with induction of oxidative stress

Chromium effects on free radical processes in goldfish tissues: comparison of Cr(III) and Cr(VI) exposures on oxidative stress markers, glutathione status and antioxidant enzymes.