Effects of organic selenium-containing diets on Penaeus vannamei molecular response under induced heat stress challenge

Abstract

Organic selenium is a major antioxidant that can protect against oxidative stresses by stimulating the antioxidant cascades. We have evaluated the capacity of dietary selenium-enriched yeast (Se-Y) to alleviate thermal stress in juvenile Penaeus vannamei shrimp. The Se-Y level in the control group (Cont) was 0 mg Se kg⁻¹ ration and 0.4 mg Se kg⁻¹ in the AlkoSel and SelPlex groups (commercial Se-Y products). The shrimp were initially provided the three experimental diets while being maintained in their thermal comfort zone (28 °C) for 30 days, following which time the temperature was increased up to 33 °C for 1 and 6 h of induced heat stress challenge (IHSC). Variations in the levels of malondialdehyde (MDA), glutathione, and several transcriptional factors encoding antioxidant variables and stress-responsive proteins were analyzed in the gill, muscle, and hepatopancreas. The results revealed that the MDA and glutathione content of the shrimp were significantly impacted by Se-Y supplementation both before and after the IHSC. Prior to the IHSC, in all evaluated tissues, Se-Y supplementation enhanced the antioxidant variables (glutathione peroxidase, glutathione-S-transferase, and superoxide dismutase) and heat shock protein (HSP) biosensors HSP70 and HSP90 while depressing the immune stress-related indices (gamma-interferon inducible lysosomal thiol reductase-like and aspartate aminotransferase cytoplasmic-like (AST). After IHSC, in all evaluated tissues, the AST gene was significantly downregulated in all Se-Y-fed groups while the other genes were upregulated. These results imply an important role of organic selenium in preventing organ dysfunctions after exposure to IHSC. Taken together, these findings on gene regulation after Se-Y pretreatment will be useful for monitoring organ dysfunction and preparing therapeutic agents for thermal endurance in P. vannamei.