Changes in hypothermal stress-induced hepatic mitochondrial metabolic patterns between fresh water- and seawater-acclimated milkfish, Chanos chanos

Abstract

Milkfish (Chanos chanos) is a tropical euryhaline species. It can acclimate to fresh water (FW) or seawater (SW) and be cultured in both. In winter, cold snaps cause huge losses in milkfish revenue. Compared to FW-acclimated individuals, SW-acclimated milkfish have better low-temperature tolerance. Under hypothermal stress, a stable energy supply is critical to maintain normal liver function. In this study, the levels of key mitochondrial enzymes (citrate synthase (CS) and cytochrome c oxidase (COX)) in milkfish livers were examined. The CS:COX activity ratio in FW milkfish significantly increased under hypothermal stress (18 °C) whereas ATP (the end product of aerobic metabolism) was downregulated. Therefore, the activities of the enzymes involved in mitochondrial amino acid biosynthesis (aspartate aminotransferase (AST) and glutamate dehydrogenase (GDH)) were evaluated to elucidate energy flow in milkfish livers under hypothermal stress. In FW milkfish, GDH activity was upregulated whereas AST activity was downregulated. Nevertheless, the levels of all the aforementioned enzymes did not significantly change in SW milkfish under hypothermal stress. In summary, we clarified the mechanism accounting for the fact that SW milkfish have superior low-temperature tolerance to FW milkfish and demonstrated that SW and FW milkfish have different and unique strategies for regulating energy flow.

Effects of temperature and salinity on antioxidant responses in livers of temperate (Dicentrarchus labrax) and tropical (Chanos Chanos) marine euryhaline fish

“…In winter, high mortalities have been recorded during cold snaps, which have caused enormous economic losses in Taiwan (Liao, 2016). Previous studies have shown that SW-acclimated milkfish exhibit a better cold tolerance than FW-acclimated fish (Kang et al, 2015), notably through differential energy utilization pathways (Chang et al, 2019(Chang et al, , 2020.…”

Quantitative Proteomic Analysis of Yorkshire Pig Liver Reveals Its Response to High Altitude

“…Among them, citrate synthase (CS), isocitrate dehydrogenase (IDH), and oxoglutarate dehydrogenase complex (OGDC) are the key enzymes in the TCA cycle. Previous studies found that the activity of CS, a key enzyme catalyzing the first step of the TCA cycle, was significantly increased and ATP was downregulated ( p < 0.05) in the livers of flounders under hypothermic stress . In contrast, the enzyme (p00889; 0.706-fold) expression level was significantly decreased in SNY livers ( p < 0.05).…”

“…Previous studies found that the activity of CS, a key enzyme catalyzing the first step of the TCA cycle, was significantly increased and ATP was downregulated (p < 0.05) in the livers of flounders under hypothermic stress. 20 In contrast, the enzyme (p00889; 0.706fold) expression level was significantly decreased in SNY livers (p < 0.05). As we did not explore the specific energy production, we can only speculate that plateau cold stress may induce a low activity state in CS.…”

Genetic variants of IFIH1 and DHX58 affect the chronicity of hepatitis C in the Chinese Han population

“…It suggested that the synergistic effects of LGP2 and MDA5 may be inconsistent in individuals with different levels of AST, resulting in an antiviral response that is the opposite. The activity of AST is known to be involved in the biosynthesis of mitochondrial amino acids ( Kirsch et al, 1984 ; Chang, Liu & Lee, 2019 ). Animal experiments show that the liver injury group showed higher mitochondrial oxygen consumption, higher enzyme activity, and higher ATP levels.…”