Antioxidant stress response to fluctuations of dissolved oxygen and temperature in a semi-intensive aquaculture shrimp farm during high summer temperature

Abstract

The enhancement of the antioxidant system in response to oxidative stress caused by environmental conditions has been amply reported in several animals. In many cases, the studies were done in controlled laboratory conditions and few studies are available under natural or semi-natural settings. In a shrimp farm with semi-intensive culture exposed to natural high temperature and oxygen changes, we evaluated selected antioxidant enzymes gene expression and enzymatic activity, as biochemical indicators. Also, for cell stress, carbonylated proteins and caspase-3 were evaluated, and lactate content for the shift to anaerobic metabolism in Litopenaeus vannamei. The shrimp were collected at four time-points: highest temperature (T1); an intermediate time-point (T2, control); lowest dissolved oxygen (T3) and reoxygenation (T4) conditions. In gills, antioxidant enzymes and caspase-3 expression were up-regulated during T3 and T4 compared to the control, carbonylated proteins were reduced, and the activity of antioxidant enzymes was unaffected. At T1, only the expression of mMnSOD was induced and lactate content was maintained in all sampling points. In hepatopancreas, only cMnSOD expression in T3 and T4 was induced. Carbonylated protein levels were unaffected in all sampling points, but at T1 and T4, caspase-3 expression increased, and antioxidant enzymes activity was reduced. Lactate content decreased in T3 and T4. Our results show a rapid response by the antioxidant enzymes of L. vannamei and endurance to cope with environmental changes in a semi-intensive aquaculture pond.