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.

• Authors: Matilde Forcella, Elisa Berra, Roberto Giacchini, Paolo Parenti
• Journal: Archives of insect biochemistry and physiology (Arch Insect Biochem Physiol) Vol. 65 Issue 4 Pg. 181-94 (Aug 2007) ISSN: 0739-4462 [Print] United States
• PMID: 17630655 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Amino Acid Transport Systems
• Amino Acids
• Antioxidants
• Reactive Oxygen Species

Topics

• Adaptation, Physiological
• Amino Acid Transport Systems (metabolism)
• Amino Acids (metabolism)
• Animals
• Antioxidants (metabolism)
• Carbohydrate Metabolism
• Chironomidae (enzymology, metabolism)
• Hypoxia (metabolism)
• Larva (enzymology, metabolism)
• Oxidative Stress (physiology)
• Reactive Oxygen Species (metabolism)