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This study was conducted to investigate the effects of dietary synthetic β‐carotene on growth performance, haematological and immunological parameters, energy reserves and antioxidant status of juvenile fish Piaractus mesopotamicus. Two hundred and ten fish (12.24 ± 2.98 g) were fed with a control extruded feed (CEF) and the same diet supplemented with β‐carotene (BEF) for 90 days. A higher weight gain and specific growth rate were found in fish fed BEF in comparison with those fed CEF. In addition, BEF‐fed fish showed lower liver somatic index and a higher percentage of eosinophils. No statistical differences were found in energy reserves, except for plasma triglycerides which decreased in fish fed with BEF. Regarding oxidative stress markers, decreased activities of antioxidant enzymes were found in intestine and gills of BEF‐fed fish (SOD and GST, respectively). In the liver, both LPO levels and CAT activity decreased in fish fed with BEF. Additionally, lower brain LPO levels without changes in the antioxidant enzymes were observed in BEF‐fed fish. The inclusion of dietary synthetic β‐carotene improved growth and antioxidant status, and had a plasma triglyceride‐lowering effect in juvenile P. mesopotamicus.  相似文献   
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This study evaluated the histopathological changes in gills and liver of Prochilodus lineatus inhabiting the Salado River basin. Fish were collected in four different sampling stations. The histological lesions in the tissues were examined under light microscopy and evaluated with quantitative analyses. The morphometric analysis of the gills showed a significant shortening of secondary lamellae and a lower percentage of area for gas exchange in fish from station 1 (an urban area, located near the mouth of the Salado River) in comparison with fish gills from the reference site (station 4, a relatively pristine area). Moreover, a significantly higher area occupied with necrotic foci and the occurrence of an important inflammatory response were observed in fish liver of station 1 than the samples caught from other stations. Thus, histopathological evidences showed differences among sites, which could be related to different environmental conditions.  相似文献   
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Among the most extensively used compounds for the pest control in Argentinean crops is the organochlorine endosulfan. The sublethal effects of the commercial endosulfan formulation on hematology and lipid peroxidation (LPO) of the neotropical fish Prochilodus lineatus were investigated. Firstly, we calculated acute toxicity (LC50) in order to define sublethal concentrations (0, 1.2, and 2.4 ??g L?1). Hematological and oxidative stress responses were assessed at 24, 48, and 96 h. Endosulfan exposure significantly diminished the hemoglobin concentration, mean cell hemoglobin, and total plasma protein and increased white blood cells count and plasma glucose after 96 h. Exposed fish showed an alteration of the differential leukocytes count, evidenced by more thrombocytes and monocytes and less lymphocytes and neutrophils. Endosulfan increased LPO levels in intestine, liver, and brain in both sublethal concentrations. The present results suggest that endosulfan produces biochemical and physiological alterations, including immunological disorders, and it is a good inductor of oxidative stress in P. lineatus.  相似文献   
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Fish Physiology and Biochemistry - This study aimed to analyze the cold stress effects (in terms of hematology, energy reserves, and oxidative stress) in Piaractus mesopotamicus (pacú) and...  相似文献   
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This study aimed at investigating the physiological responses of Piaractus mesopotamicus exposed to high stocking density and the potential protective role of supplemented diets. Fish were fed with basal, red seaweed (Pyropia columbina) or β‐carotene‐supplemented diets for 90 days. Then, fish were distributed at low (1.5 g/L) and high (22 g/L) stocking densities for 15 days. Fish exposed to the high density showed increased hepatosomatic index, haemoglobin content and mean corpuscular haemoglobin concentration (all diets); decreased haematocrit, mean corpuscular volume (basal and seaweed) and white blood cells count (all diets) were observed. High density‐exposed fish showed decreased plasmatic metabolites as well as the hepatic lipids content in basal and seaweed diets. Regarding oxidative stress, increased activity of glutathione S‐transferase in high density‐exposed fish muscle (all diets), and lower lipid peroxidation in liver (basal and β‐carotene) and intestine (basal and seaweed) were evidenced. Interactions between diet and stocking density were recorded regarding the triglycerides (decrease in fish exposed to high density fed with basal and seaweed) and hepatic lipids (decrease in fish exposed to high density fed with basal). The major changes occurred in haematologic and metabolic parameters as strategies to cope with overcrowding stress. Fish response to stocking density was not affected by diets.  相似文献   
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An 84‐day feeding trial was conducted to evaluate the addition of bovine plasma protein concentrate (BPP) as a full replacement of fish meal (FM) in extruded aquafeeds for the fish Piaractus mesopotamicus at two fattening stages. Fish with an initial body weight of 105.55 ± 13.48 g (1st fattening stage) and 564.50 ± 88.02 g (2nd fattening stage) received two iso‐nitrogenous and isocaloric diets with 130 g/kg of FM (FM diet—FMD) or with 130 g/kg of BPP (BPP diet—BPPD). No significant difference in growth performance was detected between dietary treatments. Fish from the 2nd fattening stage showed decreased intestinal pH and increased haemoglobin content. At the 1st fattening stage, fish fed with BPPD presented higher levels of plasma triglycerides and cholesterol, and hepatic and whole‐body lipid content, while plasma glucose and muscular glycogen were lower at the 2nd fattening stage compared with FMD‐fed fish. Fish fed with FMD showed an increase in the thiobarbituric acid reactive substances in liver at the 1st fattening stage and intestine at the 2nd one, accompanied by higher levels of hepatic catalase at the 1st fattening stage. Results suggest BPP could completely replace FM in diets for P. mesopotamicus without affecting growth performance, when FM represents 13% of the diet.  相似文献   
9.
Cyclic AMP-modulated potassium channels in murine B cells and their precursors   总被引:11,自引:0,他引:11  
A voltage-dependent potassium current (the delayed rectifier) has been found in murine B cells and their precursors with the whole-cell patch-clamp technique. The type of channel involved in the generation of this current appears to be present throughout all stages of pre-B-cell differentiation, since it is detected in pre-B cell lines infected with Abelson murine leukemia virus; these cell lines represent various phases of B-cell development. Thus, the presence of this channel is not obviously correlated with B-cell differentiation. Although blocked by Co2+, the channel, or channels, does not appear to be activated by Ca2+ entry. It is, however, inactivated by high intracellular Ca2+ concentrations. In addition, elevation of intracellular adenosine 3', 5'-monophosphate induces at all potentials a rapid decrease in the peak potassium conductance and increased rates of activation and inactivation. Therefore, potassium channels can be physiologically modulated by second messengers in lymphocytes.  相似文献   
10.
Feed chemical composition only provides information about nutrient content of a diet, but not its bioavailability. The aims were to determine mineral bioaccessibility and protein digestibility of three different fish feed, using in vitro methods and to correlate them with feed mineral retention and apparent protein digestibility measured by juvenile Piaractus mesopotamicus model, considering elliptical joint confidence region (EJCR) of weighted least‐squares analysis. For in vivo assays, juvenile P. mesopotamicus were randomly stocked into conical tanks and fed during 38 days with a commercial diet, an experimental diet, or the same experimental diet added with phytase (0.2 g/kg). Total body mineral retention (mineral bioavailability indicator) and apparent protein digestibility of different diets were measured. For in vitro methods, mineral dialysability (mineral bioaccessibility indicator) and protein digestibility of the same diets were determined. No significant difference in morphometric and haematological markers were detected between diets. For iron, zinc and phosphorous bioavailability, and protein digestibility, weighted least‐squares analysis showed the optimal point (1, 0) was included in EJCR, indicating in vivo and in vitro methods were comparable and correlated satisfactorily. In vitro methods were able to reproduce accurately the results obtained from traditional in vivo assays using juvenile P. mesopotamicus model.  相似文献   
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