Daily variations in oxygen consumption, antioxidant defenses, and lipid peroxidation in the gills and hepatopancreas of an estuarine crab.

This study identified daily variations in oxygen consumption, antioxidant-defense system, and lipoperoxidation in the gills and hepatopancreas of the crab Chasmagnathus granulata (Dana, 1851) (Decapoda, Brachyura). In gills, oxygen consumption was higher in the early afternoon and in the middle of the night (p < 0.05). Lipoperoxidation level and non-proteic sulfhydryl content were higher in the middle of the night (p < 0.05). The enzyme glutathione-S-transferase showed lower activity at the end of photophase and higher values during the night (p < 0.05). The enzyme catalase did not show daily variation in activity (p > 0.05). Oxygen consumption in the hepato pancreas showed a similar profile to that in gills, i.e., higher values in the early afternoon and the middle of the night. Glutathione-S-transferase activity and lipoperoxidation levels showed significant variation, with lower values during the afternoon and peaks in the middle of the night (p < 0.05). Catalase activity was significantly higher (p < 0.05) in the middle of the night. The non-proteic sulfhydryl content remained fairly constant (p > 0.05). The results showed daily variations in aerobic metabolism of the gills and hepatopancreas of C. granulata, with concomitant oxidative damage (lipoperoxidation), but with differences between tissues. Whereas in the gills the defense system focused on catalase and non-proteic sulfhydryl, in the hepatopancreas other non-enzymatic components and other antioxidant enzymes besides catalase and glutathione-S-transferase might be involved. [ABSTRACT FROM AUTHOR]