Antioxidant defenses preserve membrane transport activity in Chironomus riparius larvae exposed to anoxia

Abstract

Changes in enzyme activities, metabolite concentrations, and membrane transport activity underlying the Chironomus riparius larvae adaptive response to anoxia were investigated. Trehalose, malate, and aspartate degradation and alanine accumulation were recorded. During anoxia exposure, there was a boost of antioxidant defenses as shown by an increase of the specific activity of the enzymes catalase, glutathione-S-transferase, glutathione peroxidase, glutathione-synthase, malic enzyme, and NADP-dependent isocitrate dehydrogenase. The ratio, glutathione reduced over glutathione oxidized, decreased. Except for alanine and catalase, the parameters return to their basal value when larvae are transferred to normoxic conditions. To test whether antioxidant defenses had protective effects on membrane functionality, L-leucine uptake into brush border membrane vesicles and membrane lipid peroxidation was measured. No difference between membranes prepared from larvae exposed to anoxia and control larvae was found. The amino acid alanine, when present inside the vesicles, trans-stimulated leucine uptake. This effect could represent a mechanism to stimulate amino acid uptake and catabolism in vivo when free alanine concentration increases during hypoxic periods.

Short-term anoxic conditioning hormesis boosts antioxidant defenses, lowers oxidative damage following irradiation and enhances male sexual performance in the Caribbean fruit fly, Anastrepha suspensa

“…The increased activity of GPx during anoxia and the consistent activity thereafter correlate with the production of hydrogen peroxide resulting from the dismutation of superoxide. We did not observe an increase in catalase activity during anoxia or after reperfusion, but perhaps the concentration of hydrogen peroxide was not high enough to warrant elevated levels from what is already high catalase activity in caribflies compared with other flies (Grubor-Lajsic et al, 1996;Forcella et al, 2007).…”

Impact of High Temperature Gradients on the Physiolgical and Biomolecular Changes in the Tropical Tasar Silkworm Antheraea mylitta D

“…This also confirms that proteins are not a source of energy in the stress condition but are involved in the modulation of silkworm physiological activity to protect from temperature stress [29]. Some new proteins synthesized are also involve in the metabolic synthesis of biomolecules such as glycerol, sorbitol and other polyols acts as thermoprotectants [30,31] are synthesize in the tissues and release into the hemolymph to protect organisms during adverse conditions like temperature stresses [32]. Some important sugar compounds are synthesized during non-feeding stage of the silkworm as a source to meet the emergent energy needs as well as their utilization in the production of some new proteins/ biomolecules to cope with the temperature stress.…”

Accumulation and effects of cyanobacterial microcystins and anatoxin-a on benthic larvae of Chironomus spp. (Diptera: Chironomidae)

“…living in the presence of cyanobacterial blooms and in a bloom-free ecosystem to high concentrations of cyanotoxins, however, may be due to their very high content of the antioxidant GSH and GSH/GSSG ratio (a biomarker of antioxidant potential). As stated by Forcella et al (2007), Chironomus riparius Meigen contained 200-300 m GSH g -1 F.W. and the GSH/GSSG ratio was also high (23.7-28.8).…”

“…Altogether, this indicates that Chironomus larvae may possess some specific defence against cyanotoxins. Forcella et al (2007) recorded an increase in specific enzymes, including glutathione-S-transferase, glutathione peroxidase and glutathione synthase, in Chironomus larvae under oxidative stress. Both MCs and ANTX cause oxidative stress in aquatic organisms (Blaha et al, 2004), and glutathione (GSH), a strong antioxidant, plays an essential role in coping with this stress.…”