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Titolo:
EFFECTS OF ZINC ON THE KINETICS OF BRANCHIAL CALCIUM-UPTAKE IN FRESH-WATER RAINBOW-TROUT DURING ADAPTATION TO WATERBORNE ZINC
Autore:
HOGSTRAND C; WILSON RW; POLGAR D; WOOD CM;
Indirizzi:
MCMASTER UNIV,DEPT BIOL HAMILTON L8S 4K1 ON CANADA
Titolo Testata:
Journal of Experimental Biology
, volume: 186, anno: 1994,
pagine: 55 - 73
SICI:
0022-0949(1994)186:<55:EOZOTK>2.0.ZU;2-U
Fonte:
ISI
Lingua:
ENG
Soggetto:
SALMO-GAIRDNERI RICHARDSON; OREOCHROMIS-MOSSAMBICUS; SALVELINUS-FONTINALIS; CADMIUM INHIBITION; PROTEIN-SYNTHESIS; BROOK TROUT; FLUX RATES; SOFT-WATER; LOW PH; METALLOTHIONEIN;
Keywords:
FISH; RAINBOW TROUT; ONCORHYNCHUS MYKISS; GILLS; ZINC; CALCIUM; TRANSPORT KINETICS; ACCLIMATION; ADAPTATION; TOLERANCE; METALLOTHIONEIN; PROTEIN SYNTHESIS; RNA;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
50
Recensione:
Indirizzi per estratti:
Citazione:
C. Hogstrand et al., "EFFECTS OF ZINC ON THE KINETICS OF BRANCHIAL CALCIUM-UPTAKE IN FRESH-WATER RAINBOW-TROUT DURING ADAPTATION TO WATERBORNE ZINC", Journal of Experimental Biology, 186, 1994, pp. 55-73

Abstract

The effects of sublethal waterborne Zn2+ (150 mu g 1(-1)=2.3 mu mol 1(-1)) on the kinetics of unidirectional Ca2+ influx were studied in juvenile freshwater rainbow trout during chronic exposure (60 days) at awater [Ca2+] of 1.0 mmol 1(-1). An unexposed group held under identical conditions served as control. The presence of Zn2+ in the water increased the apparent K-m for Ca2+ influx by up to 300 % with only a small inhibitory effect (35 % at most) on the maximum rate of uptake (J(max)) These results, in combination with earlier data showing that Ca2competitively inhibits Zn2+ uptake, suggest that Zn2+ and Ca2+ compete for the same uptake sites. Acute withdrawal of Zn2+ after 3 h of exposure resulted in a 23-fold reduction in K-m for Ca2+, but a persistent small depression of J(max) During prolonged exposure to Zn2+, the apparent K-m for Ca2+ remained greatly elevated and J(max) remained slightly depressed. The actual Ca2+ influx in hard water ([Ca2+]=1.0 mmol 1(-1)) decreased marginally and paralleled the small changes in J(max). The increases in apparent K-m had a negligible influence on the actual Ca2+ influx because K-m values (38-230 mu mol 1(-1)), even when elevated by Zn2+, remained below the water [Ca2+] (1000 mu mol 1(-1)). Rainbow trout exposed to Zn2+ exhibited a slower rate of protein synthesis in the gills (measured on day 23) and an increased tolerance to Zn2 challenge (measured on both days 27 and 50). Unidirectional Zn2+ influx, measured at the end of the exposure period, was significantly reduced in the Zn2+-exposed fish. There were no changes in hepatic or branchial Zn2+, Cu2+ or metallothionein concentrations. We hypothesize that, during exposure to sublethal [Zn2+] in hard water, the fish may change the K-m for a mutual Ca2+/Zn2+ carrier so as to reduce markedly Zn2+ influx without greatly altering Ca2+ influx. This reduced Zn2+ influx, rather than metallothionein induction, may be the basis of adaptation to elevated concentrations of waterborne Zn2+.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 20/01/21 alle ore 15:59:25