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Juvenile channel catfish (Ictalurus punctatus) were fed with nutritionally complete, basal diets supplemented with NaCl at 0, 10, 20 or 40 g kg?1 diet (0, 1, 2, or 4%) to apparent satiation twice daily for 10 weeks. Catfish were exposed to nitrite after six (7.70 mg L?1 nitrite‐N) and ten (7.18 mg L?1 nitrite‐N) weeks of feeding to determine the effect of dietary NaCl supplementation on resistance to nitrite toxicity. Fish were sampled before (baseline, pre‐exposure) and after 24‐h nitrite exposure to determine the effects of dietary NaCl on haematology (haematocrit, haemoglobin and methaemoglobin) and plasma electrolyte dynamics (nitrite, chloride, sodium and potassium). Mortality from nitrite toxicity was also determined. Mortality from nitrite exposure tended to decrease with increasing NaCl in the diet at 6 weeks and was significantly lower in the 40 g kg?1 NaCl group (12.5%) compared to the control group (57.5%). A similar trend in mortality occurred at 10 weeks as well; however, the differences among dietary treatments were not significant. The improvements in blood MetHb (non‐significant), chloride and nitrite levels in catfish may at least in part be responsible for the improved survival after nitrite exposure, which trended in support of the prevailing hypotheses for the positive effects of NaCl on nitrite toxicity. 相似文献
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Sung Hee Jung Doo Saing Sim Mi-Seon Park QTae Jo & Yoon Kim 《Aquaculture Research》2003,34(14):1269-1275
Erythrocytes of olive flounder, Paralichthys olivaceus (Temminck et Schlegel), were treated with serial concentrations of formalin (37% formaldehyde) to investigate in vitro haemolysis and methaemoglobin formation. In addition, the short‐term toxicity of formalin concentrations of 0, 100, 212 and 300 ppm was also studied by clinical tests in which fish were subjected to 3‐h bath exposure. There was no haemolysis of fish erythrocytes exposed to formalin concentrations ranging from 31.3 to 2000 ppm. Methaemoglobin formation, however, was induced at concentrations greater than 500 ppm. Red blood cell count, haemoglobin, haematocrit, mean corpuscular haemoglobin concentration and percentage of immature erythrocytes were also markedly elevated in all formalin‐exposed groups (P<0.05). Formalin exposure also caused significant increases in alkaline phosphatase, aspartate aminotransferase, lactate dehydrogenase, potassium, chloride, magnesium and inorganic phosphorus (P<0.05). However, total protein decreased significantly in the formalin‐exposed groups (P<0.05). No significant differences in white blood cell count, mean corpuscular volume, mean corpuscular haemoglobin, albumin, glucose, total cholesterol, high‐density lipoprotein cholesterol, free cholesterol, alanine aminotransferase, calcium, creatinine and total bilirubin were observed in the formalin‐exposed groups (P>0.05). 相似文献
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Frank B. Jensen 《Fish physiology and biochemistry》1993,12(2):111-117
Oxidation of rainbow trout haemoglobin (Hb) by nitrite proceeded via an initial lag phase followed by autocatalysis when the O2 saturation of the Hb was high. At low O2 saturations, the rate of methaemoglobin (metHb) formation was strongly reduced and autocatalysis was absent. Addition of
adenosine triphosphate and guanosine triphosphate to oxyHb lowered the haemoglobin O2 affinity and O2 saturation and slowed down nitrite-induced metHb formation in a dose-dependent manner, the effect of GTP being larger than
that of ATP. Reduced nicotinamide adenine dinucleotide (NADH) and the catecholamines adrenaline and noradrenaline did not
affect O2 saturation in oxyHb solutions but significantly slowed down nitrite-induced metHb formation. Inorganic salts (NaCl, KCl,
NaNO3) impeded the oxidation of oxyHb by nitrite in a manner that was dependent on salt concentration but independent of the type
of salt. The mechanisms and physiological implication of the effects are discussed. 相似文献
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Ive Marchioni Avilez Lucia Helena de Aguiar Tiago Silvestre Hori Gilberto Moraes 《Aquaculture Research》2013,44(4):596-603
Nitrite is usually found in aquatic environments where nitrification process occurs. This ion can cause several injuries to aquatic species, particularly fish. Nitrite reacts with haemoglobin yielding the non‐functional methaemoglobin, which leads to many physiological consequences such as functional anaemia and supposed hypoxia. Metabolism of the freshwater teleost matrinxã, Brycon amazonicus, exposed to environmental 0.6 mg L?1 of nitrite N‐NO2? for 96 h was studied, and the fermentative/oxidative preference was gauged. Concentrations of glycogen, glucose, lactate, pyruvate and ammonia, plus the activities of lactate, glutamate and malate dehydrogenase were assayed. The exposure resulted in a metabolic profile that allowed inferring the continuity of oxidative metabolism. Catabolism of amino acids prevailed or was apparently exacerbated by inferred branchial injury and consequent impairment of nitrogen excretion. Moreover, the studied enzymes glutamate dehydrogenase, lactate dehydrogenase and malate dehydrogenase from brain and heart were little affected by nitrite. The expected fermentative metabolism due to the high methaemoglobin formation was not observed. 相似文献
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Chronic exposure to nitrate significantly reduces growth and affects the health status of juvenile Nile tilapia (Oreochromis niloticus L.) in recirculating aquaculture systems 
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下载免费PDF全文 Studies on chronic or acute toxicity of nitrogen species on fish in recirculating aquaculture systems (RAS) usually focused on adverse effects of total ammonia nitrogen (TAN: sum of NH3 + NH4+) and nitrite (), while underestimating the potential effects of high nitrate accumulation on growth and health status of fish. In our study, Nile tilapia (Oreochromis niloticus) were exposed to five different nitrate concentrations (0, 10, 100, 500 and 1000 mg L?1 ‐N) over 30 days. Growth parameters (feed conversion ratio (FCR), specific growth rate (SGR), hepatosomatic index (HSI)), blood samples (concentrations of haemoglobin, methaemoglobin, plasma /) and the histology of the gills were studied to evaluate growth and health status of the fish. At the highest nitrate concentration, the fish showed significantly reduced growth and impaired health status (SGR, FCR, plasma /, haemoglobin and methaemoglobin concentration), demonstrating that too high nitrate concentrations can negatively influence tilapia production in RAS. Here, we recommend not exceeding concentrations of 500 mg L?1 ‐N in juvenile tilapia culture to ensure an optimal health and growth status of the fish, as below that concentration no effects on the tilapia have been observed. 相似文献
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