Metabolic adjustments in the common carp during prolonged hypoxia

Abstract

Biochemical and respiratory changes in the common carp Cyprinus carpio were studied 6, 24, 96 and 168 h upon exposure to hypoxia (0·5 mgO 2 l 1 ). Modification of kinetic properties of phosphofructokinase (PFK-1), coupled with a decreased in PFK-1 activities, were evident in muscle. No changes in kinetics and activities could be observed in muscle pyruvate kinase (PK) and lactate dehydrogenase (LDH). A decrease in muscle citrate synthase (CS) and an increase in muscle cytochrome c oxidase (CCO) were found. The common carp was able to maintain a constant level of muscle glycogen, muscle ATP, and liver CS throughout the 168-h experimental period. Changes in activities of liver LDH and muscle CCO were observed only at 168 h, which indicates that common carp may switch to alternative metabolic pathway to deal with prolonged hypoxia. A severe decrease in liver glycogen was accompanied by increases in lactate levels in both the muscle and liver. Oxygen consumption rate was reduced under hypoxia, but resumed to normoxic levels within 2 h upon return to normoxic condition. Overall, these results indicate that carp adopt different strategies in an attempt to deal with short term and long term hypoxia in the natural environment. 2000 The Fisheries Society of the British Isles

Low O2 acclimation shifts the hypoxia avoidance behaviour of snapper (Pagrus auratus) with only subtle changes in aerobic and anaerobic function

“…Elevation of these ratios suggests that when snapper are chronically challenged by low P O2 (10.2-12.1kPa), anaerobic systems may compensate for constrained aerobic ATP synthesis. Similar increases in anaerobic potential have been observed in other species of fish exposed to periods of chronic hypoxia (Greaney et al, 1980;Johnston and Bernard, 1982;Ton et al, 2003;Yang et al, 1992;Zhou et al, 2000), but not in others (Driedzic et al, 1985;Martínez et al, 2006;Zhou et al, 2000). Whilst these adjustments in anaerobic enzyme activity were possibly important to snapper during moderate long-term hypoxia (10.2-12.1kPa), hypoxia-acclimated fish in the behavioural trials also showed signs of improved low-O 2 tolerance at sub-critical P O2 levels (<7kPa), where fish would likely struggle to meet basal…”

Hypoxia-inducible myoglobin expression in nonmuscle tissues

“…The liver plays a key role in the hypoxia-adaptation of the common carp, primarily through the up-regulation of anaerobic metabolism (15,16). We now provide another potentially important hypoxia-adaptive response in this tissue, namely the substantial up-regulation of MYG-1 protein expression in liver and other nonmuscle tissues through a transcriptional mechanism.…”

Histopathological indicators: a useful fish health monitoring tool in common carp (Cyprinus carpio Linnaeus, 1758) culture

“…Higher values, however, such as those detected in ponds with tube well water, are able to affect fish metabolism [32], causing physiological changes and reduced growth [33], although increased mortality was not reported. Besides salinity, carp is also tolerant to low levels of DO and can survive for more than 7 days in the water with 0.5 mg/L of DO [34]. COD levels were high, as compared to natural freshwater, but these levels are tolerated in semi-intensive aquaculture and are related to the quantity of supplemented feed [27].…”