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The effects of elevated dietary calcium (as CaCO sub(3)) and acute waterborne Cd exposure (50 mu g/l) on whole body uptake, tissue uptake, and internal distribution of newly accumulated Cd, Ca super(2+), and Na super(+) in juvenile rainbow trout were examined. Fish were fed with three diets (mg Ca s...
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The effects of commercial dissolved organic carbon (DOC) in moderating accumulation, biochemical responses and toxicity of a waterborne mixture of copper (Cu), cadmium (Cd) and zinc (Zn) were investigated during a chronic exposure. Juvenile rainbow trout (Oncorhynchus mykiss) were exposed to a terna...
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Thermal tolerance and the respiratory properties of isolated red muscle mitochondria were investigated in Oreochromis alcalicus grahami from the alkaline hot-springs, Lake Magadi, Kenya. Populations of O. a. grahami were resident in pools at 42.8 °C and migrated into water reaching temperatu...
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Juvenile rainbow trout (Oncorhynchus mykiss) were exposed to 11 (control), 300 (medium), and 1000 mug Cu.g(1) (high) (as CuSO(4)5H(2)O) in the diet for 28 days at a daily ration of 4% wet body weight, with a background waterborne Cu concentration of 3 mug.L-1. There was no effect of dietary Cu on gr...
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Exploitation of natural mineral deposits and subsequent re-deposition in aquatic environments at levels potentially harmful to biota necessitate regulation of environmental discharge of metals. Proper environmental regulation of metals requires adequate knowledge on the bioavailability and effects o...
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Ecological risk assessment (ERA) of inorganic metals and metalloids (metals) must be specific to these substances and cannot be generic because most metals arc naturally occurring, some are essential, speciation affects bioavailability, and bioavailability is determined by both external environmenta...
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Interactions of Cu, Cd and Zn were studied at the subcellular level in juvenile rainbow trout (Oncorhynchus mykiss) fed diets containing (mug/g) 500 Cu, 1000 Zn and 500 Cd singly and as a ternary mixture for 28 days. Livers were harvested and submitted to differential centrifugation to isolate compo...
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Non-essential metals such as cadmium (Cd) accumulated in animal cells are envisaged to partition into potentially metal-sensitive compartments when detoxification capacity is exceeded. An understanding of intracellular metal partitioning is therefore important in delineation of the toxicologically r...
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The thermostability of haemoglobin was measured in three species of fish living at different environmental temperatures (ET). The time (min) for 50% denaturation (T sub(1/2)d) of the haemoglobin at 2 mg ml super(-1) in 50 mM phosphate buffer, pH 7.3 was 46.4 plus or minus 1.7 for Oreochromis alcalic...
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Juvenile rainbow trout Oncorhynchus mykiss were exposed to diets with low (12.6 nmol g(-1)), normal (50.4 nmol g(-1)) or elevated (4437.5 nmol g(-1)) Cu concentrations in combination with either low (5.8 nmol l(-1)) or normal (48.5 nmol l(-1)) waterborne Cu levels over a 50-day period, during which ...
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The present study examined the interactions between elevated dietary calcium (as ionic Ca2+ in the form of CaCl2 x 2H2O) and acute waterborne Cd exposure (50 microg/l as CdNO3 for 3 h) on whole body uptake and internal distribution of newly accumulated Cd, Ca2+, and Na+ in juvenile rainbow trout (On...
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Waterborne Cu is toxic to Na(+) and Cl(-) regulation in freshwater fish, and Cu is taken up, at least in part, via the Na(+)-transport pathway in the gills. Therefore, we hypothesized that freshwater fish may mitigate the toxic effects of waterborne Cu by selecting a NaCl-enriched diet over a normal...
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Rainbow trout Oncorhynchus mykiss fry in moderately hard water were exposed to control or high levels of dietary Cu (c. 6 and 580 ug Cu g food-1) at one of three levels of Na (1.5, 3.0 or 4.5%) in the diet, i.e. six experimental groups. Fish were fed a 4% body mass ration daily for 28 days and 10 in...
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The kidneys of four freshwater teleost fish Oreochromis niloticus, Micropterus salmoides, Cyprinus carpio and Clarias mossambicus and one marine teleost, Chanos chanos, representing Perciformes (O. niloticus and M. salmoides) Ostariophysi (C. carpio, and C. mossambicus) and Salmoniformes (C. chanos)...
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Measurement of circulatory indicators of copper (Cu) exposure and toxicity in rainbow trout revealed elevated Cu concurrent with reduced sodium (Na) concentrations in plasma of Cu-exposed fish. Using a new normal phase high performance liquid chromatography (HPLC) method developed and validated for ...
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Juvenile rainbow trout (Oncorhynchus mykiss) were exposed to waterborne Cu (22 microg/l) in moderately hard water for up to 28 days. Relative to control fish kept at background Cu levels (2 microg/l), Cu-preexposed fish displayed decreased uptake rates of waterborne Cu via the gills but not of dieta...
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Juvenile rainbow trout were fed diets containing control (0.26 mmol/g) or elevated (1.3 mmol/g) dietary Na+ in combination with either background (19 nmol/L) or moderately elevated levels (55 or 118 nmol/L) of waterborne Cu for 21 d. Unidirectional waterborne Na+ uptake rates (measured with 22Na) we...
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Ultrastructural studies were carried out on the nephron of a euryhaline teleost, Oreochromis niloticus. The nephron consisted of a renal corpuscle, neck segment, bisegmental proximal tubule and a distal tubule. Renal corpuscles displayed a trilaminate structure of fenestrated endothelium, triple lay...
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Rainbow trout embryos and larvae were continuously exposed (at 12.5 degrees C) to waterborne silver in a flow-through setup, from fertilization to swim-up, at nominal silver concentrations of 0, 0.1, or 1.0 microg/L total silver (as AgNO(3)) at three different water Cl(-) levels (30, 300, and 3,000 ...
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Juvenile rainbow trout (Oncorhynchus mykiss) maintained on either low sodium chloride (LS (control), 1.4% NaCl) or high sodium chloride (HS, 11% NaCl) diet were exposed to 55 micro g.L-1 waterborne copper (Cu) for 28 days. Cu-exposed fish maintained on the LS diet exhibited 26% mortality, more than ...
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Kidneys of four fresh water teleost species representing percormorpha (Oreochromis niloticus and Micropterus salmoides) and Ostariophysi (Cyprinus carpio and Clarias mossambicus) were studied for quantitative structural characteristics using tissues fixed by perfusion. The renosomatic index (weight ...
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A study was carried out to determine the euryhalinity and the effect of salinity changes on the drinking of tilapia, Oreochromis andersoni. Drinking rate of the fish in fresh water, and at 50%, 75% and 100% sea water was determined. O. andersoni acclimated to sea water without mortality and fish acc...
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Ours is the first study to demonstrate an influence of dietary sodium on waterborne copper uptake in fish. We examined possible interactions between dietary sodium and the response of freshwater rainbow trout (Oncorhynchus mykiss) to waterborne copper in light of recent evidence of interactions betw...
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The influence of ration size on homeostasis and sublethal toxicity of copper (Cu) was assessed in rainbow trout (Oncorhynchus mykiss) during dietary Cu exposure in synthetic soft water. A constant dietary dose of 0.24 micromol Cu per g fish per day as CuSO(4).5H(2)O was delivered via diets containin...
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The Lake Magadi tilapia (Alcolapia grahami) is an unusual fish, excreting all its nitrogenous waste as urea because of its highly alkaline and buffered aquatic habitat. Here, using both physiological and molecular studies, we describe the mechanism of branchial urea excretion in this species. In viv...
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To protect cells from toxicity, metal-sensitive cellular compartments must be insulated against essential but toxic metals [such as copper (Cu)] accumulated in excess of metabolic requirements. We measured Cu concentrations at the organ and hepatic subcellular levels in juvenile rainbow trout (Oncor...
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Rates of oxygen consumption were measured in the geothermal, hot spring fish, Oreochromis alcalicus grahami by stopped flow respirometry. At 37 degree C, routine oxygen, consumption followed the allometric relationship: Vo sub(2)=0.738 M super(0.75), where Vo sub(2) is ml O sub(2)/h and M is body ma...
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Rainbow trout were exposed to sublethal waterborne Cd (5 and 10mugL(-1)) and dietary Ca (60mgg(-1)), individually and in combination, for 30d to elucidate the interactive effects and evaluate the toxicological significance of mitochondrial responses to these cations in vivo. Indices of fish conditio...
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Zinc homeostasis was studied at the tissue and gill subcellular levels in rainbow trout (Oncorhynchus mykiss) following waterborne and dietary exposures, singly and in combination. Juvenile rainbow trout were exposed to 150 or 600 μg l−1 waterborne Zn, 1500 or 4500 μg g−1 dietary Zn, and a com...
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We investigated the interaction of temperature and copper (Cu) on mitochondrial bioenergetics to gain insight into how temperature fluctuations imposed by natural phenomena or anthropogenic activities would modulate the effects of Cu on cellular energy homeostasis. Mitochondria were isolated from ra...
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Molecular features of cadmium (Cd) and calcium (Ca) uptake and toxicity in rainbow trout liver mitochondria were studied using modulators of mitochondrial permeability transition pore (MPTP), mitochondrial calcium uniporter (MCU) and rapid uptake mode (RaM). Malate-glutamate energized mitochondria w...
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Impairment of the electron transport chain (ETC) is implicated in cadmium (Cd)- and calcium (Ca)-induced mitochondrial dysfunction. To localize the sites of the impairment, effects of 0-50μM Cd and Ca, singly and in combination, on complex I- to IV-driven respirations were investigated using isolat...
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The goal of the present study was to elucidate the modulatory effects of cadmium (Cd) on hypoxia/reoxygenation-induced mitochondrial dysfunction in light of the limited understanding of the mechanisms of multiple stressor interactions in aquatic organisms. Rainbow trout (Oncorhynchus mykiss) liver m...
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The goal of the present study was to elucidate the modulatory effects of cadmium (Cd) on hypoxia-reoxygenation-induced mitochondrial dysfunction in light of the limited understanding of the mechanisms of multiple stressor interactions in aquatic organisms. Rainbow trout (Oncorhynchus mykiss) liver m...
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There have been suggestions that analgesics be used by fish researchers. But in the absence of dose-response data for morphine, this suggestion seems imprudent. The purpose of the present study was to develop a dose-response relationship in fish using six doses of morphine. The response (movement of...