Metabolic response of Nile tilapia (Oreochromis niloticus) to acute and chronic hypoxia stress

Abstract

Hypoxia is a critical issue in aquaculture especially in intensive aquaculture systems.Acute hypoxia stress with dissolved oxygen (DO) 0.7±0.1 mg/L for 6 h and chronic hypoxia stress with DO 1.1±0.1 mg/L for 4 weeks were used to investigate the response of nutritional metabolic pathways in Nile tilapia Oreochromis niloticus. Fish in the acute and chronic experiments had different adaptive mechanisms. Upon acute hypoxia stress, the contents of liver glycogen and muscle glycogen were significantly lower, but there was no significant difference in triglycerides (TG). The lactate dehydrogenase (LDH) activities increased after exposure to acute hypoxia stress. The mRNA expression of genes involved in glycolysis and glycogenolysis was significantly up-regulated by acute hypoxia stress. However, the response of fish to long-term hypoxia stress was different from acute hypoxia. Compared with the normoxia treatment, the crude fat in fish decreased in the hypoxia group and TG in the liver and muscle were significantly lower.Beta oxidation of the liver was enhanced in the hypoxia group, while the hepatic glycogen content increased in the hypoxia group. Transcriptomic analysis showed that the expression of genes related to carbohydrate synthesis and lipolysis increased in the hypoxia group, while genes related to carbohydrate catabolism and fat synthesis showed the opposite. This study indicates that fish could utilize carbohydrate as a main energy source during acute hypoxia stress, and metabolize more lipid during long-term hypoxia stress. A high carbohydrate content in the diet may help reduce negative effects from acute hypoxia stress, and an appropriate increase of fat content in the diet may benefit fish growth in a hypoxia environment, e.g., in high-density aquaculture ponds.

Hepatopancreas Transcriptome Profiling Analysis Reveals Physiological Responses to Acute Hypoxia and Reoxygenation in Juvenile Qingtian Paddy Field Carp Cyprinus carpio var qingtianensis

“…We observed that DEGs in HH versus CH and RH versus HH groups were significantly enriched for glycolysis/gluconeogenesis, fructose and mannose metabolism, pyruvate metabolism, and TCA cycle. This is similar to previous studies of fish energy metabolism based on carbohydrate during hypoxia and reoxygenation (Li et al, 2018). The expression of pfk, hk, and ldh genes were up-regulated to enhance the glycolysis and lactic acid metabolism pathway and acly genes was down-regulated and to inhibit the TCA cycle, which resulted in the transformation of hepatopancreatic cells from aerobic respiration to anaerobic respiration during hypoxia (Ding et al, 2020).…”

Physiological Responses of Pacific White Shrimp Litopenaeus vannamei to Temperature Fluctuation in Low-Salinity Water

“…It has been widely accepted that protein acts as the main energy source for shrimp (New, 1976; Zhang et al, 2006; Cuzon et al, 2010). Research has shown that lipids are the main energy source of tilapia ( Oreochromis niloticus ) during long-time hypoxia stress (Li et al, 2018). In this study, the results showed that lipids (TC, the major components of lipids, supply and store energy) and protein (TP provides energy and transports various metabolites) in plasma responded more rapidly to temperature fluctuation, while Glu remained stable before 13°C and recovered to AT levels after temperature rose back to 28°C.…”

Effects of Fish Stocking Density on Water Quality, Growth Performance of Tilapia (Oreochromis niloticus) and Yield of Butterhead Lettuce (Lactuca sativa) Grown in Decoupled Recirculation Aquaponic Systems

“…The mean values of the water T in this study for both time intervals were higher than the recommended range for lettuce plant, that is, 20°C to 26°C (Resh 2012). Other than T and pH, DO is also one of the most critical environmental factors linked to the proper physiological functions of tilapia and is a limiting factor for the lifespan of fish (Zhao et al, 2018;Li et al, 2018). In this study, it was observed that higher stocking density had a lower DO level.…”