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Titolo:
THE ADAPTATIONS OF FISH TO EXTREMELY ALKALINE ENVIRONMENTS
Autore:
WILKIE MP; WOOD CM;
Indirizzi:
UNIV TORONTO,DIV LIFE SCI,SCARBOROUGH CAMPUS SCARBOROUGH ON M1C 1A4 CANADA MCMASTER UNIV,DEPT BIOL HAMILTON ON CANADA
Titolo Testata:
Comparative biochemistry and physiology. B. Comparative biochemistry
fascicolo: 4, volume: 113, anno: 1996,
pagine: 665 - 673
SICI:
0305-0491(1996)113:4<665:TAOFTE>2.0.ZU;2-A
Fonte:
ISI
Lingua:
ENG
Soggetto:
ACID-BASE REGULATION; LAHONTAN CUTTHROAT TROUT; LAKE MAGADI TILAPIA; CHALCALBURNUS-TARICHI CYPRINIDAE; OREOCHROMIS-ALCALICUS-GRAHAMI; ONCORHYNCHUS-CLARKI-HENSHAWI; NITROGENOUS WASTE EXCRETION; WATER RAINBOW-TROUT; AMMONIA EXCRETION; UREA EXCRETION;
Keywords:
AMMONIA; UREA; CHLORIDE CELL; ACID-BASE BALANCE; LAKE MAGADI TILAPIA; RAINBOW TROUT; CUTTHROAT TROUT; ION BALANCE; HIGH PH;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
65
Recensione:
Indirizzi per estratti:
Citazione:
M.P. Wilkie e C.M. Wood, "THE ADAPTATIONS OF FISH TO EXTREMELY ALKALINE ENVIRONMENTS", Comparative biochemistry and physiology. B. Comparative biochemistry, 113(4), 1996, pp. 665-673

Abstract

The Lake Magadi Tilapia (MT; Oreochromis alcalicus grahami, the Lahontan cutthroat trout (LCT; Oncorhynchus clarki henshawi) and the tarek (Ct; Chacalburnus tarichi) have evolved unique strategies that allow them to overcome problems associated with ammonia excretion (J(Amm)) and acid-base regulation in their alkaline environments. In Lake Magadi,Kenya (pH 10), the MT circumvents problems associated with J(Amm) by excreting virtually all (>90%) of its waste-nitrogen as urea. Base excretion appears to be facilitated by modified seawater-type gill chloride cells, through apical Cl-/HCO3- exchangers and an outwardly directed OH-/HCO3-/CO3= excretion system. The LCT avoids potentially toxic increases in internal ammonia by permanently lowering ammonia productionrates following transfer into alkaline (pH 9.4) Pyramid Lake, Nevada,from its juvenile freshwater (pH 8.4) environment. Greater apical exposure of LCT gill chloride cells, presumably the freshwater variety, probably facilitates base excretion by elevating Cl-/HCO3- exchange capacity. In Lake Van, Turkey (pH 9.8) high ammonia tolerance enables C. tarichi to withstand the high internal ammonia concentrations that it apparently requires for the facilitation of J(Amm) It also excretes unusually high amounts of urea. We conclude that adjustments to nitrogenous waste metabolism and excretion patterns, as well as modifications to gill functional morphology, are necessary adaptations that permit these animals to thrive in environments considered unsuitable for most fishes.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 08/07/20 alle ore 08:09:53