Arsenic toxicity in mammals and aquatic animals: A comparative biochemical approach

Abstract

Arsenic (As) is a widespread pollutant in the world and its toxicity is related to its chemical form, with inorganic forms being considered more toxic than the organic form, and huge differences in effects and processes of metabolism. This paper reviews the potential biochemical mechanisms of uptake of arsenic by aquaporins, capacity for metabolism and cellular efflux of As. It is known that As can affect signaling pathways since it can activate proteins such as ERK2, p38 and JNK, as shown in mammals. A comparison between phosphorylation sites of these proteins is presented in order to determine whether the same effect triggered by As in mammals might be observed in aquatic animals. The toxicity resulting from As exposure is considered to be linked to an imbalance between pro-oxidant and antioxidant homeostasis that results in oxidative stress. So, present review analyzes examples of oxidative stress generation by arsenic. Biotransformation of As is a process where firstly the arsenate is converted into arsenite and then transformed into mono-, di-, and trimethylated products. In the methylation process, the role of the omega isoform of glutathione-S-transferase (GST) is discussed. In addition, a phylogenetic tree was constructed for aquaporin proteins of different species, including aquatic animals, taking into account their importance in trivalent arsenic uptake.

Advances made in Understanding the Effects of Arsenic Exposure on Humans

“…In addition, another route of human exposure to arsenic toxicity is through dietary consumption of arsenic-contaminated food. Both flora and fauna, an essential component of human diet, get exposed to arsenic through atmospheric emission from anthropogenic activities like mining and smelting operations, and also through agricultural sources like insecticides, herbicides, wood preservatives, pesticides, fertilizers and growth stimulants for plants and animals 3,[5][6][7][8] . Even though arsenic is bioconcentrated by flora and fauna, it does not get biomagnified in the food chain 9 .…”

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“…Their deleterious impacts on different economically important aquatic animals like fishes are manifold (Lima et al, 2010). Although the contamination levels in natural ecosystems are usually well below the limits that can cause mortality in exposed animals, these may be sufficient to impair the normal functioning of tissues.…”

Heavy Metals Content in Paraphilometroides nemipteri from South China Sea may Influence Level of Glutathione and P38 Protein Expression

“…A review by Ventura-Lima et al (2011), reported that arsenic in aquaporins could affect signalling pathways by activating proteins such as ERK2, p38 and JNK as demonstrated in mammals. In this study, we believed that parasites might undergo stress when they accumulate metals in their body.…”