A comparative study of reactive oxygen species in red muscle: pressure effects.

International audienceIn ectotherms as well as in endotherms, the mitochondrial respiratory chain is the major source of reactive oxygen species (ROS) including the highly reactive, hydroxyl radical (OH*). It is known that the different steps involved in ROS production and the antioxidant systems are comparable in ectotherms and endotherms. But regulatory mechanisms in ROS production are less known especially in fish submitted to environmental changes. Firstly, we performed a ROS muscle metabolism interspecies study, using trout and eels as ectotherms and rats as endotherms, measuring OH* production, superoxide dismutase and catalase activities and in parallel oxygen consumption (MO2). Secondly, we studied the effects of an environmental factor (hydrostatic pressure) on ROS metabolism in both fish species. The results show that, at atmospheric pressure, fish have a higher OH*/MO2 ratio than rats which exhibit a higher superoxide dismutase activity. In fish exposed to hydrostatic pressure, this ratio is reversed so that for the same MO2 value, fish produce less OH* under hydrostatic pressure than at atmospheric pressure

A comparative study of reactive oxygen species in red muscle: pressure effects.

International audienceIn ectotherms as well as in endotherms, the mitochondrial respiratory chain is the major source of reactive oxygen species (ROS) including the highly reactive, hydroxyl radical (OH*). It is known that the different steps involved in ROS production and the antioxidant systems are comparable in ectotherms and endotherms. But regulatory mechanisms in ROS production are less known especially in fish submitted to environmental changes. Firstly, we performed a ROS muscle metabolism interspecies study, using trout and eels as ectotherms and rats as endotherms, measuring OH* production, superoxide dismutase and catalase activities and in parallel oxygen consumption (MO2). Secondly, we studied the effects of an environmental factor (hydrostatic pressure) on ROS metabolism in both fish species. The results show that, at atmospheric pressure, fish have a higher OH*/MO2 ratio than rats which exhibit a higher superoxide dismutase activity. In fish exposed to hydrostatic pressure, this ratio is reversed so that for the same MO2 value, fish produce less OH* under hydrostatic pressure than at atmospheric pressure

Does hydrostatic pressure have an effect on reactive oxygen species in the eel?

International audienceEels are submitted to hydrostatic pressure (HP) during their spawning migration (about 6000 Km). Before migration, they change from the yellow to the silver stage (silvering process). The effects of HP in relation to the silvering process have been studied on aerobic metabolism and more precisely on reactive oxygen species (ROS) metabolism. HP acclimatization of yellow eels improves oxidative phosphorylation together with supposed concomitant changes in electron leak and ROS production. Therefore hydroxyl radical (OH*) production, superoxyde dismutase and catalase activities, malondialdehyde content and in parallel oxygen consumption were measured in the red muscle of long-term pressure exposed and control group yellow and silver eels. At atmospheric pressure, yellow eels exhibited significantly higher oxygen consumption and OH* production than silver eels; and significantly lower malondialdehyde content. This could be due to the increase in membrane fluidity induced by the silvering process. Long-term HP exposure decreases yellow eel oxygen consumption which becomes similar to that of the silver stage. In parallel there is a decrease in OH* production and concomitantly antioxidant enzyme activities follow the same tendency. Thus the respiratory chain improvement in pressure acclimatized yellow eels is accompanied by a ROS production decrease which could mean an electron leak decrease

Does hydrostatic pressure have an effect on reactive oxygen species in the eel?

International audienceEels are submitted to hydrostatic pressure (HP) during their spawning migration (about 6000 Km). Before migration, they change from the yellow to the silver stage (silvering process). The effects of HP in relation to the silvering process have been studied on aerobic metabolism and more precisely on reactive oxygen species (ROS) metabolism. HP acclimatization of yellow eels improves oxidative phosphorylation together with supposed concomitant changes in electron leak and ROS production. Therefore hydroxyl radical (OH*) production, superoxyde dismutase and catalase activities, malondialdehyde content and in parallel oxygen consumption were measured in the red muscle of long-term pressure exposed and control group yellow and silver eels. At atmospheric pressure, yellow eels exhibited significantly higher oxygen consumption and OH* production than silver eels; and significantly lower malondialdehyde content. This could be due to the increase in membrane fluidity induced by the silvering process. Long-term HP exposure decreases yellow eel oxygen consumption which becomes similar to that of the silver stage. In parallel there is a decrease in OH* production and concomitantly antioxidant enzyme activities follow the same tendency. Thus the respiratory chain improvement in pressure acclimatized yellow eels is accompanied by a ROS production decrease which could mean an electron leak decrease

Sex-related differences in aerobic capacities and reactive oxygen species metabolism in the silver eel.

International audienceSilver European eels (Anguilla anguilla L.) need to develop important aerobic capacities to cope with their long fasting spawning migration at depth, particularly males which are about half the size of females. Moreover, they have to face potential oxidative stress because reactive oxygen species (ROS) production is linked to the increase in metabolic rate. Thus, aerobic metabolism was globally evaluated in male and female silver eels exposed to a 10.1 MPa hydrostatic pressure (1,000 m depth). Oxygen consumption (MO(2)), ROS production and antioxidant enzyme activities were measured in the muscle fibres. Males showed a trend in both higher rate of aerobic metabolism and ROS production than females. After pressure exposure, ROS production was inversely correlated to metabolic rate only in males. By facilitating MO(2) rise with no harmful effects by ROS, the supposed enhanced aerobic capacities of males could speed up the sustained swimming. In females, the tendency to lower metabolic rate and higher catalase activity would make them less vulnerable to ROS effects. These results are in agreement with the hypothesis for different migration depths between genders

Fish as a model in investigations about the relationship between oxygen consumption and hydroxyl radical production in permeabilized muscle fibers.

International audienceMitochondrion is the main production site for reactive oxygen species (ROS). In endotherms, the existence of a positive relationship between ROS production and metabolic rate is acknowledged. But, little is known about ectotherms, especially fish, with a metabolic rate dependent on the environmental temperature. The maximal oxygen consumption and the production of highly reactive hydroxyl radicals by permeabilized red muscles of yellow and silver eels and trouts were measured concomitantly and compared to those of rats chosen for their comparable body mass, but different metabolic rate. The positive correlation found in fish between the metabolic rate and the ROS production showed a shift with respect to mammals

Bioenergetic transcriptomic responses of European flounder (Platichthys flesus) populations in contrasted environments: impacts of pollution and global warming

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