Effects of environmental anoxia and different periods of reoxygenation on oxidative balance in gills of the estuarine crab Chasmagnathus granulata
We investigated the effects of anoxia (8 h) and different periods of reoxygenation (20 and 40 min) on the oxidative balance in anterior and posterior gills of the crab Chasmagnathus granulata. Enzyme activity of catalase and GST was increased in the gills of the animals submitted to anoxia, and SOD activity was decreased. These enzymes returned approximately to control levels during the anoxia recovery time. These results demonstrated enzyme activities change with variations in environmental oxygen levels. The posterior gills showed a higher antioxidant enzyme activity than anterior gills. In the gills, there were no changes in the non-enzymatic antioxidant system (TRAP) during anoxia. On the other hand, during anoxia recovery, an increase of TRAP in both gills was observed. Anoxia does not change lipid peroxidation (TBARS) in the gills. During anoxia recuperation, an increase in levels of TBARS was observed. Thus the results demonstrate that C. granulata has a similar strategy of preparation for oxidative stress as observed in other intertidal species, enabling the crabs to survive in an environment with extreme variations in physical and chemical characteristics, such as salt marshes.
Available from: Gustavo A Lovrich
- "The decrease of proteins in March and only in the hepatopancreas could be related to the surplus of energy required for molting during April–June. In crustaceans, protein contents and its seasonal variation have been attributed to its role as an energy source, as well as with the availability and type of food (Oliveira et al., 2005; Vinagre et al., 2007). A decrease of protein content in the muscle of the crayfish Parastocus varicosus during the period of food scarcity may contribute to the maintenance and survival (da Silva-Castiglioni et al., 2007). "
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ABSTRACT: Environmental and physiological variations influence the steady-state concentration of free oxygen radicals in cells. Because of the seasonal life cycle of Lithodes santolla in the Beagle Channel, a baseline study of the antioxidant physiological variations along the seasons is necessary for a better understanding of its ecophysiology. The aim of this study was to evaluate the seasonal variations in gills, haemolymph, muscle and hepatopancreas of the: i) enzymatic activities of superoxide dismutase, catalase, glutathione peroxidase and glutathione transferase; ii) ascorbic acid and total glutathione; iii) lipid peroxidation and protein oxidation; iv) glucose, proteins and pH. Seasonality found in the antioxidant defense system of L. santolla from the Beagle Channel acts in a collaborative way during the most relevant life cycle phases (reproduction and molting), avoiding a long term oxidative stress. The antioxidant system also shows changes in the enzymatic activities likely caused by the environmental factors, such as low temperatures during winter and spring seasons.
Copyright © 2014. Published by Elsevier Inc.
Comparative Biochemistry and Physiology - Part A Molecular & Integrative Physiology 11/2014; 181. DOI:10.1016/j.cbpa.2014.11.016 · 1.97 Impact Factor
Available from: Mariana Machado Lauer
- "In the first, glycolysis seems to be the main pathway, while in the latter the main pathway seems to be the pentose phosphate shunt, which could indicate a need for NADPH to regenerate glutathione. Oliveira et al. (2005) observed a higher antioxidant protection in posterior than in anterior gills of N. granulata, probably to protect Na + , K + -ATPase from ROS damage. "
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ABSTRACT: The estuarine crab Neohelice granulata was exposed (96h) to a sublethal copper concentration under two different physiological conditions (hyperosmoregulating crabs: 2ppt salinity, 1mg Cu/L; isosmotic crabs: 30ppt salinity, 5mg Cu/L). After exposure, gills (anterior and posterior) were dissected and activities of enzymes involved in glycolysis (hexokinase, phosphofructokinase, pyruvate kinase, lactate dehydrogenase), Krebs cycle (citrate synthase), and mitochondrial electron transport chain (cytochrome c oxidase) were analyzed. Membrane potential of mitochondria isolated from anterior and posterior gill cells was also evaluated. In anterior gills of crabs acclimated to 2ppt salinity, copper exposure inhibited hexokinase, phosphofructokinase, pyruvate kinase, and citrate synthase activity, increased lactate dehydrogenase activity, and reduced the mitochondrial membrane potential. In posterior gills, copper inhibited hexokinase and pyruvate kinase activity, and increased citrate synthase activity. In anterior gills of crabs acclimated to 30ppt salinity, copper exposure inhibited phosphofructokinase and citrate synthase activity, and increased hexokinase activity. In posterior gills, copper inhibited phosphofructokinase and pyruvate kinase activity, and increased hexokinase and lactate dehydrogenase activity. Copper did not affect cytochrome c oxidase activity in either anterior or posterior gills of crabs acclimated to 2 and 30ppt salinity. These findings indicate that exposure to a sublethal copper concentration affects the activity of enzymes involved in glycolysis and Krebs cycle, especially in anterior (respiratory) gills of hyperosmoregulating crabs. Changes observed indicate a switch from aerobic to anaerobic metabolism, characterizing a situation of functional hypoxia. In this case, reduced mitochondrial membrane potential would suggest a decrease in ATP production. Although gills of isosmotic crabs were also affected by copper exposure, changes observed suggest no impact in the overall tissue ATP production. Also, findings suggest that copper exposure would stimulate the pentose phosphate pathway to support the antioxidant system requirements. Although N. granulata is very tolerant to copper, acute exposure to this metal can disrupt the energy balance by affecting biochemical systems involved in carbohydrate metabolism.
Comparative Biochemistry and Physiology Part C Toxicology & Pharmacology 08/2012; 156(3-4):140-7. DOI:10.1016/j.cbpc.2012.08.001 · 2.30 Impact Factor
Available from: Mario S Diniz
- "The HSC70/HSP70 concentrations were greatest in the near-future warming scenario for both developmental stages, with hatchlings showing the largest increase (Fig. 6C). The increased metabolic demands faced by the hatchlings must lead to elevated ROS formation, and HSPs are among the molecules that can eliminate/change the molecular configuration of ROS . Concomitantly, warming also led to an augment of MDA concentrations (see correlative values in Table S4), indicative of the enhancement of ROS action in organism’s lipids (“peroxidation”), a process considered to be one of the most frequent cellular injury mechanisms . "
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ABSTRACT: The knowledge about the capacity of organisms' early life stages to adapt to elevated temperatures is very limited but crucial to understand how marine biota will respond to global warming. Here we provide a comprehensive and integrated view of biological responses to future warming during the early ontogeny of a keystone invertebrate, the squid Loligo vulgaris.
Recently-spawned egg masses were collected and reared until hatching at present day and projected near future (+2°C) temperatures, to investigate the ability of early stages to undergo thermal acclimation, namely phenotypic altering of morphological, behavioural, biochemical and physiological features. Our findings showed that under the projected near-future warming, the abiotic conditions inside the eggs promoted metabolic suppression, which was followed by premature hatching. Concomitantly, the less developed newborns showed greater incidence of malformations. After hatching, the metabolic burst associated with the transition from an encapsulated embryo to a planktonic stage increased linearly with temperature. However, the greater exposure to environmental stress by the hatchlings seemed to be compensated by physiological mechanisms that reduce the negative effects on fitness. Heat shock proteins (HSP70/HSC70) and antioxidant enzymes activities constituted an integrated stress response to ocean warming in hatchlings (but not in embryos).
The stressful abiotic conditions inside eggs are expected to be aggravated under the projected near-future ocean warming, with deleterious effects on embryo survival and growth. Greater feeding challenges and the lower thermal tolerance limits of the hatchlings are strictly connected to high metabolic demands associated with the planktonic life strategy. Yet, we found some evidence that, in the future, the early stages might support higher energy demands by adjusting some cellular functional properties to increase their thermal tolerance windows.
PLoS ONE 06/2012; 7(6):e38282. DOI:10.1371/journal.pone.0038282 · 3.23 Impact Factor
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