The LoachMisgurnus anguillicaudatusReduces Amino Acid Catabolism and Accumulates Alanine and Glutamine during Aerial Exposure
- 1 March 2001
- journal article
- research article
- Published by University of Chicago Press in Physiological and Biochemical Zoology
- Vol. 74 (2), 226-237
- https://doi.org/10.1086/319663
Abstract
The loach Misgurnus anguillicaudatus inhabits rice fields in Southern China. It encounters drought during summer and ammonia loading during agricultural fertilization. In the laboratory, aerial exposure led to decreases in its ammonia and urea excretion. Ammonia accumulated to very high levels in the muscle and liver. Urea synthesis through the ornithine‐urea cycle was not involved in ammonia detoxification in M. anguillicaudatus. However, M. anguillicaudatus was capable of partial amino acid catabolism leading to the accumulation of alanine in the first 24 h of aerial exposure. This was apparently coupled to a possible decrease in protein/amino acid catabolism. These are not detoxification mechanisms but mechanisms that avoid internal fouling by ammonia. Misgurnus anguillicaudatus was also capable of detoxifying internally produced ammonia in part to glutamine, which appears to be an important adaptation after 24 h of aerial exposure. However, unlike the case of the marble goby (Oxyeleotris marmoratus), there was no alteration to the kinetic properties of the hepatic glutamine synthetase. During dry seasons, M. anguillicaudatus moves actively on land until it encounters soft mud in which it can bury itself through several strong wriggling actions of the body. Hence, it is possible that M. anguillicaudatus uses partial amino acid catabolism to fuel its short period of activities on land and switches to the formation of glutamine to detoxify internally produced ammonia when it remains relatively inactive in the mud.Keywords
This publication has 27 references indexed in Scilit:
- Biochemical and environmental perspectives on nitrogen metabolism in fishesCellular and Molecular Life Sciences, 1992
- Subcellular localization of two glutamine‐dependent carbamoyl‐phosphate synthetases and related enzymes in liver of Micropterus salmoides (largemouth bass) and properties of isolated liver mitochondria: Comparative relationship with elasmobranchsJournal of Experimental Zoology, 1991
- Variation in urea excretion in the gulf toadfishOpsanus betaMarine Biology, 1990
- Comparative study of ureogenesis in freshwater, air‐breathing teleostsJournal of Experimental Zoology, 1989
- Ammonia and urea dynamics in the Lake Magadi tilapia, a ureotelic teleost fish adapted to an extremely alkaline environmentRespiration Physiology, 1989
- Urea excretion as a strategy for survival in a fish living in a very alkaline environmentNature, 1989
- Active ureogenesis in a freshwater air‐breathing teleost, Heteropneustes fossilisJournal of Experimental Zoology, 1987
- Kinetic properties of cyanaseBiochemistry, 1986
- Amino acid transport and interconversions in tissues of freshly caught and food-deprived plaice, Pleuronectes platessa L.Journal of Fish Biology, 1981
- Ammonia toxicity mechanism in fish: Studies on rainbow trout (Salmo gairdneri Rich.)Ecotoxicology and Environmental Safety, 1981