Antioxidant enzyme activities and immunological system analysis of Litopenaeus vannamei reared in biofloc technology (BFT) at different water temperatures

摘要

The purpose of this study was to evaluate the effect of water temperature on the antioxidant (gills, hemolymph and hepatopancreas) and immunological systems (hemolymph) of Litopenaues vannamei reared with no water exchange. A 60-day trial was conducted at different temperatures (15, 21, 27-control and 33 degrees C), with 3 replicate tanks for each treatment. The immunologic parameters analyzed were as follows: hyaline and granular hemocyte count, total protein and apoptosis. The enzymatic and lipid peroxidation assays consisted of glutamate cysteine ligase (GCL), reduced glutathione (GSH) and thiobarbituric acid-reactive substances (TBARS). There were no significant differences (p > 0.05) in immunological parameters among treatments throughout the experimental period. Shrimp exposed to 15 degrees C at 30 days exhibited significantly higher GCL activity in gills compared to 21 degrees C (1166.28%), 27 degrees C (422.96%) and 33 degrees C (809.37%). L. vannamei reared at 15 degrees C had the highest GSH concentration at 30 days. The GSH increase in gills was 390.29, 376.94 and 361.75% at 21, 27 and 33 degrees C, respectively. On day 30, shrimp subjected to 33 degrees C had higher TBARS levels (6157.14; 8620.00 and 14,336.66% at 15, 21 and 27 degrees C, respectively). Shrimp reared at 15 degrees C exhibited higher activity of the rate-limiting compound for GSH production (GCL) and higher concentrations of this non-enzymatic antioxidant. This increased activity may counteract the overproduction of reactive oxygen species generated by temperature stress. We further noted that at 33 degrees C, the animals showed higher lipid peroxidation. The lowest stress response was observed in shrimp reared at 27 degrees C (the control group). Therefore, the extreme temperatures should be avoided.