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1.
In aquaculture, ozone is used as a disinfectant. In its production, extensive amounts of oxygen are formed resulting in hyperoxic conditions in culture units. Both ozone and hyperoxia have the potential to be toxic via pro‐oxidant mechanisms and to activate antioxidant defence systems in cultured species. To eliminate systemic effects, blood of rainbow trout, Oncorhynchus mykiss (Walbaum), was exposed in vitro for 5 min to ozone/hyperoxia or hyperoxia, and changes in antioxidant defences and lipid peroxidation were measured after exposure. Ozone exposure caused severe damage in red blood cells (rbc) detected as increased lipid peroxidation and oxidized glutathione (GSSG) levels in both plasma and rbc. Oxygen exposure alone increased intracellular lipid peroxidation and GSSG levels 10 min after exposure and was not evident in the plasma at any time. Ozone, but not oxygen exposure, decreased reduced glutathione (GSH) levels in plasma, and the changes were negatively correlated with increased lipid peroxidation in rbc, indicating that extracellular GSH has a dynamic role in the protection of rbc from direct oxidation by ozone. Both ozone and hyperoxic conditions increased superoxide dismutase (SOD) activity in rbc 3 and 6 h after exposure. In contrast, catalase activity was only increased 10 min after oxygen exposure, suggesting other catalase activation mechanisms rather than enzyme induction. The recovery of lipid peroxidation and GSSG levels in rbc after hyperoxia, but not ozone exposure, indicated a capacity to defend against hyperoxia‐produced oxidative damage, but an overwhelming of antioxidant defences by ozone in rainbow trout rbc in vitro.  相似文献   

2.
Although thermal influences on the physiology of rainbow trout (Oncorhynchus mykiss) have been widely studied, there is little information about the responses of different genetic strains to temperatures. The effects of water temperature (10, 14, 19, 22, and 25 °C) on food consumption rate, growth rate, gross conversion efficiency, resting routine oxygen consumption rate, upper critical thermal tolerance and critical swimming velocity were investigated in juvenile rainbow trout of the Eagle Lake (O. m. aquilarum) subspecies and the Mt. Shasta strain. No strain-related differences in conversion efficiency, oxygen consumption rates, thermal tolerance or swimming performance were observed in 1995 (19, 22, and 25 °C) or 1996 (10, 14, and 19 °C), but Mt. Shasta strain trout grew faster at highest temperatures than did Eagle Lake trout. Food consumption rates, growth rates, conversion efficiency, and oxygen consumption rates declined at the extreme temperatures (10 and 25 °C) in both Eagle Lake and Mt. Shasta trout. Swimming performance was temperature-independent between 10 and 19 °C (overall mean: 5.43 body lengths s–1).  相似文献   

3.
Methemoglobin is oxidized hemoglobin that cannot bind to or dissociate from oxygen. In fish, it is most commonly caused by exposure to excess nitrites and can lead to abnormal swimming, buoyancy, or death. The methemoglobin concentration in mammals is determined by the balance of oxidizing agents versus reducing enzymes in erythrocytes. The objective of our studies was to characterize the enzymes that reduce methemoglobin in fish erythrocytes. Whole blood was collected from healthy rainbow trout. Methemoglobin was induced in vitro by NaNO2 exposure. Methemoglobin reduction in controls was compared to reduction in samples with added NADH, NADPH, or NADPH and methylene blue. Rainbow trout whole blood was also fractionated into cytosol, microsomal, and mitochondria/plasma membranes/nuclei fractions. The fractions were compared for NADH-dependent cytochrome b5 reductase (CB5R) activity and for nitrite induction of methemoglobin. The CB5R activity in rainbow trout erythrocytes was compared to the CB5R activity in equine, feline, and canine erythrocytes. Rainbow trout erythrocytes had significant NADPH methemoglobin reductase activity in the presence of methylene blue (P < 0.001). The CB5R activity was greatest (P < 0.001) in the plasma membrane/mitochondria/nuclei fraction. The CB5R activity in rainbow trout erythrocytes was not significantly different than canine or equine activity but was significantly lower than feline CB5R activity (P < 0.0001). Methemoglobin in rainbow trout erythrocytes can be reduced by CB5R or NADPH-dependent methemoglobin reductase. Unlike mammalian anuclear erythrocytes, which are dependent on soluble CB5R, the nucleated RBCs of rainbow trout use membrane-bound CB5R to reduce methemoglobin.  相似文献   

4.
Methemoglobin is hemoglobin containing ferric iron. Methemoglobin cannot bind to oxygen and at high concentrations causes tissue hypoxia. Brook trout (Salvelinus fontinalis) develop significantly greater methemoglobinemia than Atlantic salmon (Salmo salar) or rainbow trout (Oncorhynchus mykiss) following general anesthesia with benzocaine or tricaine methanesulfonate. The objective of this study was to compare the activity of the major methemoglobin reducing enzyme, NADH-dependent cytochrome b5 reductase (CB5R), in brook trout erythrocytes to the activity of CB5R in Atlantic salmon and rainbow trout erythrocytes. Methemoglobin levels were compared using co-oximetry following in vitro incubation of erythrocytes with sodium nitrite (NaNO2). The CB5R activity was measured using a ferricyanide assay. There was significantly greater methemoglobin at time 0 in brook trout erythrocytes than in rainbow trout or Atlantic salmon erythrocytes (2.79 ± 0.29 %, 2.19 ± 0.23 %, 2.08 ± 0.14 %), (P < 0.001). There was significantly greater methemoglobin induction by NaNO2 in brook trout erythrocytes (33.14 ± 3.32 %) than in rainbow trout or Atlantic salmon erythrocytes (28.73 ± 2.92 % and 24.85 ± 1.40 %, respectively), (P < 0.001). The CB5R activity was significantly less in brook trout erythrocytes (median of 3.05 μmol/min/μl) than in rainbow trout erythrocytes (median of 6.73 μmol/min/μl). The CB5R activity in Atlantic salmon erythrocytes (median 4.09 μmol/min/μl) was not significantly different than in brook or rainbow trout erythrocytes. Total methemoglobin at any one time is a balance between induction by oxidants and reduction by antioxidants. Lower CB5R activity in brook trout erythrocytes may contribute to a species-specific sensitivity to methemoglobin induction; however, there are likely additional factors.  相似文献   

5.
The plasma inhibitor of carbonic anhydrase (CA) from rainbow trout was purified using ion exchange chromatography. The inhibitor has a high isoelectric point value (pI>10). SDS-PAGE electrophoresis and gel filtration demonstrated that the inhibitor is a low molecular weight compound of about 6,000 daltons. The plasma inhibitor was more effective against gill CA than against blood CA in vitro, probably reflecting the presence of various CA-isoenzymes in red blood cells and gill tissue. The apparent Root effect, i.e., the impairment of the oxygen binding capacity of hemoglobin in red blood associated with increased blood PCO 2was counteracted by the plasma inhibitor, probably by acting on membrane-bound and/or cytosolic blood CA. This interaction may be of importance in adaptive mechanisms, e.g., during the acidemic phase, when the fish is being acclimated to hypercapnic conditions.  相似文献   

6.
Most previous studies of the temperature-induced restructuring of phospholipid molecular species composition have examined steps in the biosynthesis of phospholipids to explain the accumulation of unsaturated fatty acids in membranes of cold-acclimated poikilotherms. In contrast, the present study explores the role of phospholipases in this restructuring process by determining the rates of degradation of specific molecular species of phosphatidylcholine, using enzymes (microsomes) freshly isolated from the liver of rainbow trout. (Oncorhynchus mykiss) acclimated to either 5° or 20°C. The substrate preparation employed to assay phospholipase activity possessed a range of molecular species, all radiolabeled with 1-14C-palmitic acid at thesn-1 position, similar to that present in native trout liver microsomes. After defined periods of incubation (120 and 240 min at 5°C; 60 and 120 min at 20°C), phospholipids were extracted from the reaction mixture and the distribution of radioactivity among the molecular species of phosphatidylcholine was determined by HPLC/liquid scintillation counting. In general, molecular species catabolism was not significantly influenced by either assay or acclimation temperature. Only in 20°C-acclimated fish did a reduction in assay temperature (from to 20 to 5°C) result in significantly increased proportions of radioactivity being recovered in one polyunsaturated fatty acid-containing species (16:0/22:6-PC). It is concluded: 1) that phospholipase specificity, assayed under conditions approximating thosein situ, is not significantly influenced by temperature; and 2), that the increased proportions of unsaturated fatty acid-containing molecular species of phosphatidylcholine observed at low temperatures must reflect the specificity of biosynthetic rather than degradative processes.  相似文献   

7.
This study assessed the effects of two artificial photoperiods (LD 24:0 and LD 12:12) and three temperature regimes (9, 11, and 18°C) for 30 days on haematological parameters of trout (Oncorhynchus mykiss) kept in freshwater. Samples were taken at days 7, 14, and 30 during exposure to treatments. A higher mortality (22%) and lower oxygen concentration (<8.0 mg/l) were associated with the combination of photoperiod LD 24:0 and 18°C. The LD 24:0 photoperiod (independently of temperature) increased the haematocrit and the number of erythrocytes at days 7, 14, and 30 (P < 0.01). A temperature of 18°C (independently of photoperiod regimes) diminished the number of total leucocytes, lymphocytes and thrombocytes (P < 0.01). The LD 24:0 photoperiod (also independently of temperature) lowered the number of lymphocytes only after 14 days of experimentation (P < 0.01). Interaction between artificial photoperiod and temperature was only observed at day 14 for polychromatophils (P < 0.01). These results resemble the effects of stress caused by elevated temperatures and the application of continuous light photoperiods, indicating that survival risks may develop in trout farming when this combination is met.  相似文献   

8.
Rainbow trout, Oncorhynchus mykiss, were exposed to 48h of environmental hypoxia (water partial pressure of oxygen = 8.0 kPa) at either 5 or 15°C. Blood was sampled during hypoxia via a dorsal aorta cannula to measure arterial blood partial pressure of oxygen and plasma catecholamine concentrations. After 48h, the number (Bmax) and dissociation constant (Kd) of red blood cell surface -adrenoceptors were determined using a radioligand-displacement binding assay. At 5°C, plasma catecholamine levels were elevated at 24h whereas at 15°C, levels were elevated at 48h. At either temperature, following 48h of hypoxia, there was no change in Bmax or Kd of red blood cell surface -adrenoceptors, compared to normoxic control fish. This study demonstrates that chronic exposure to moderate hypoxia does not affect the number or affinity of cell surface -adrenoceptors on trout red blood cells.  相似文献   

9.
Proliferative kidney disease (PKD) of salmonids caused by Tetracapsuloides bryosalmonae causes high mortalities of wild brown trout (Salmo trutta fario) and farmed rainbow trout (Oncorhynchus mykiss) at elevated water temperatures. Here the aim was to compare the temperature‐dependent modulation of T. bryosalmonae in the two salmonid host species, which display different temperature optima. We used a novel experimental set‐up in which we exposed brown trout and rainbow trout to an identical quantified low concentration of T. bryosalmonae for a short time period (1 hr). We followed the development of the parasite in the fish hosts for 70 days. PKD prevalence and parasite kinetics were assessed using qPCR. Exposures were performed at temperatures (12°C and 15°C) that reflect an environmental scenario that may occur in the natural habitat of salmonids. T. bryosalmonae infection was confirmed earliest in brown trout kept at 15°C (day 7 post‐exposure) while, in all other groups, T. bryosalmonae was not confirmed until day 15 post‐exposure. Moreover, significantly greater infection prevalence and a faster increase of parasite intensity were observed in brown trout kept at 15°C than in all other groups. These results indicate that PKD is differentially modulated by water temperature in related host species.  相似文献   

10.
This study investigated the protective effects of 1 mM Vitamin C and 1 mM Trolox on kinematic and oxidative stresses in rainbow trout (Oncorhynchus mykiss) sperm cells against flower‐like zinc oxide nanoparticles (ZnO‐NP, 1 mg/L) in vitro, during 2 hr. Trolox showed protective effects on all kinematic parameters measured for sperm cells against ZnO‐NPs, whereas Vitamin C only affected angular path velocity (VAP), linearity (LIN) and amplitude of lateral displacement of the sperm cell head (ALH). Although ZnO‐NPs reduced total glutathione (TGSH) and catalase (CAT) compared with the control, there were positive treatment effects for both Trolox and Vitamin C on antioxidant capacity. Conversely, while ZnO‐NP increased the rate of malondialdehyde (MDA) lipid peroxidation, it decreased following antioxidant therapy. This research suggests that Trolox and Vitamin C play a protective role for rainbow trout sperm exposed to ZnO‐NP.  相似文献   

11.
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12.
Juvenile brook trout were fed on six isonitrogenous and isolipidic diets, containing graded levels of gelatinized corn starch (50, 100, 150, 200, 250, 300 g/kg diet) for 81 days. Cellulose was used to compensate carbohydrate loss. The weight gain, specific growth rate and protein efficiency ratio increased as the dietary carbohydrate level increased from 50 to 150 g/kg, but decreased thereafter (p < .05). Quadratic regression analysis revealed that the optimum dietary carbohydrate level was in the range of 187.1–194.1 g/kg. In addition, serum alanine transaminase and aspartate transaminase activities, as well as glucose content, were highest in the group fed on 300 g/kg carbohydrate (p < .05). The hepatic malondialdehyde level increased with dietary carbohydrate levels (p < .05). The hepatic lysozyme activity increased as dietary carbohydrate level increased from 50 to 150 g/kg and decreased thereafter (p < .05). The overall survival rate after hypoxia challenge (45 min; dissolved oxygen content: 2.2 mg L?1) decreased with dietary carbohydrate levels (p < .05). Taken together, these results suggested that optimal level of dietary carbohydrate could improve growth performance. However, excessive dietary carbohydrate intake (> 250 g/kg) may decrease innate immunity status, increase oxidative stress and reduce resistance to hypoxia stress in brook trout.  相似文献   

13.
In order to meet the demand of salmon market, Chinese scientists and entrepreneurs are working on salmon mariculture far offshore in the Yellow Sea, China. Rainbow, steelhead trout and Atlantic salmon were selected as the main culture species. The aims of the present study were as follows: (a) investigate the effect of the salinity acclimation method on the growth, osmoregulation and energy budget in two forms of Oncorhynchus mykiss, rainbow and steelhead trout and (b) explore the optimal size of steelhead trout for the seawater entry. In trial I, rainbow (mean = 99.44 g) and steelhead trout (mean = 99.01 g) were reared for 40 days after undergoing salinity acclimation at three rates: an abrupt increase in salinity from 0 to 30 g/L (T30); an abrupt increase in salinity to 14 g/L, followed by a daily increase of 2 g/L (T2) or 6 g/L (T6) until reaching 30 g/L; and no salinity exposure (control treatment) (T0). In trial II, steelhead trout with body weights of approximately 100 and 400 g were cultured for 60 days with two treatments, T0 and T2, and the specific growth rate (SGR) was calculated every 10 days. In trial I, in both kinds of fish, the optimal growth performance, survival rate, osmoregulation and energy budget were observed in the T0 treatment, followed by the T2 treatment. These results indicate that O. mykiss with a body weight of approximately 100 g can adapt to sea water with a gradual transition (T2), but they are still not suitable for the seawater entry because of low growth. Based on the recorded SGRs in trial II, our formulated regression formula revealed that approximately 200 g is the optimal size of steelhead trout for the transition to sea water.  相似文献   

14.
We examined the ionoregulatory responses to temperature changes in two species of freshwater fish that differ in thermal preferences; the stenothermal, cold-water rainbow trout (Oncorhynchus mykiss) and the more eurythermal, warm-water common shiner (Notropis cornutus). We found that rainbow trout maintained constant plasma Na+ levels over the entire temperature regime (5–20 °C). Upon transfer from 15 °C (holding temperature) to 5 and 10 °C, rainbow trout experienced a significant drop in Na+ uptake (Jin Na), but after two weeks Jin Na had upregulated to warm temperature levels. Further, Na+ efflux (Jout Na) fell significantly at the colder temperatures. As a result, trout at the lowest temperatures were still in ion balance. When trout were exercised to exhaustion both O2 consumption (MO2) and Jout Na rose significantly at all temperatures, but while MO2 continued to be dependent upon temperature, Jout Na was high and constant. In contrast to the trout, common shiners experienced a 20% drop in plasma Na+ at 5 °C. Upon exposure to cold temperatures they experienced a reduced Jin Na, and showed no signs of acclimation during the subsequent two weeks. Likewise Jout Na was constant at all temperatures. These findings raise questions regarding the degree to which fish employ homeostatic mechanisms designed to defend a set- point (i.e., steady-state) osmolarity and ionic composition.  相似文献   

15.
Interactive segregation has been suggested as the ruling competition mechanism determining niche and niche segregation between juvenile Atlantic salmon (Salmo salar) and brown trout (Salmo trutta). Results from allopatry–sympatry observations of habitat use in both nature and in experiments were contrary to predictions derived from the interactive segregation hypothesis. Habitat use parameters under natural conditions such as distance to shore for Atlantic salmon parr were nearly identical in allopatric (mean ± SD; 3.2 ± 1.4 m) and sympatric (3.3 ± 1.4 m) situations. Occupied water depths largely reflected available water, but water depths <15 cm were avoided by salmon parr. Under experimental conditions, habitat use of allopatric salmon was density independent and salmon size had only minor effects, with smaller fish being more likely to occur in the shallow. Habitat use of salmon in sympatry with trout did not differ from allopatric salmon habitat use, and only salmon size had minor effects on depth choice – occurrence of trout or fish density had no effect. Allopatric trout was in general more frequent in the shallow habitat than salmon. Habitat use of sympatric trout was affected by the occurrence of salmon and trout size, resulting in a higher use of the shallow habitats for small trout. To conclude, selective segregation has a dominant role in salmon habitat use (not affected by trout occurrence), whereas a mixed situation occurs in trout habitat use with elements of interactive segregation when competing with Atlantic salmon (affected by salmon occurrence).  相似文献   

16.
A mannose-terminated glycoprotein,125I-invertase, was taken up and degraded by isolated rainbow trout liver cells at 12°C. The uptake was inhibited by EGTA and no degradation occurred in the presence of ammonium ions. The liver cell suspension was fractionated by differential centrifugation in parenchymal and nonparenchymal cells, respectively. The parenchymal liver cells seemed to be the most active cells in uptake of labelled invertase bothin vitro andin vivo. Only negligible amounts of ligand were recovered in the nonparenchymal cells. Internalization of125I-invertase at different temperatures was demonstrated indirectly by releasing surface-bound ligand with EGTA. Ligand was internalized even at 0°C in trout liver cells.In vitro uptake of125I-invertase was inhibited by excess unlabelled invertase, by mannan and by N-acetylglucosamine.These data suggest that invertase is endocytosed by a mannose-specific pathway by the parenchymal liver cells of rainbow trout.  相似文献   

17.
The aim of this study was to investigate the oxygen binding properties of the turbot (Scophthalmus maximus) hemoglobin polymorphism with special references to pH and temperature. Hemolysate samples from the three hemoglobin genotypes Hb- I(1/1), Hb-I(1/2) and Hb-I(2/2), were tested at 10, 16 and 19 °C and at pH values 7.2, 7.5 and 7.8 at 100 mm NaCl respectively. Hb-I(2/2) had the highest oxygen affinity at all three temperatures followed by Hb- I(1/2) and Hb-I(1/1). There was a significant decrease in oxygen affinity with increasing temperature and increasing pH in the range 10 to 19 °C for all three genotypes. The genotype Hb-I(1/1) had the highest Bohr effect followed by genotype Hb-I(2/2) and Hb-I(1/2). The effect was highest at 10 °C and decreased with temperature. Temperature sensitivity of the O2 binding for turbot hemoglobin was low and increased in general with increasing pH. It is hypothesised that the low sensitivity hemoglobins may be an adaptation to variable temperature conditions in the distribution area of the species.  相似文献   

18.
The dynamics of catecholamine (CA)-synthesis enzymes have been poorly studied in fish. Tyrosine hydroxylase (TH), the rate-limiting enzyme of CA synthesis has been only studied inin vitro conditions. In the present report thein vivo CA synthesis and the CA metabolism were studied in different regions of the forebrain of the rainbow trout. Levels of norepinephrine (NE), dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC) and the rate of accumulation of 3,4-dihydroxyphenylalanine (DOPA) were determined by HPLC following a treatment with hydroxybenzylhydrazine (NSD), a potential inhibitor of DOPA decarboxylase. Kinetics of the accumulation of DOPA and of the decline of DOPAC were in agreement with those found in rat, evidencing that the accumulation of DOPA following NSD can be used in trout to quantify thein vivo enzymatic activity of tyrosine hydroxylase. Experiments using treatment with NSD or with methyl-p-tyrosine reached a same conclusion: the DA neuronal activity in trout is much higher than NE neuronal activity. However, the hypothalamus had high DA levelsvs. lowin vitro andin vivo TH activities and exhibited a low CA turnover.  相似文献   

19.
Weissella ceti is an emerging bacterial pathogen that affects rainbow trout, Oncorhynchus mykiss (Walbaum), farms. The aims of this study were to genotype W. ceti strains isolated from distinct geographical origins and to determine the efficacy of an oil-adjuvanted vaccine against the disease. Between 2010 and 2012, outbreaks were recorded in five Brazilian farms, and 34 W. ceti isolates were genetically characterized by repetitive extragenic palindromic PCR, enterobacterial repetitive intergenic consensus sequences PCR and pulsed-field gel electrophoresis. Two different W. ceti vaccines were tested: an aqueous-based whole-cell inactivated vaccine (bacterin) and oil-adjuvanted vaccine. Their efficacy was evaluated in rainbow trout at 30 and 60 days post-vaccination (d.p.v.). W. ceti was found to be a highly homogeneous population in Brazil, with clonally related genotypes. Oil-adjuvanted vaccine exhibited the best (P < 0.05) protection against disease, reaching relative percentage survival (RPS)values of 92% at 30 and 60 d.p.v. Bacterin resulted in RPS values of 67% and 58% at day 30 and 60, respectively. The oil-adjuvanted vaccine provided effective protection against W. ceti infection in rainbow trout.  相似文献   

20.
White spot syndrome virus (WSSV) is the most lethal pathogen of cultured shrimp. Previous studies done with undefined WSSV titers showed that high water temperature (32-33 °C) reduced/delayed mortality of WSSV-infected shrimp. This study evaluated the effect of high water temperature on the clinical and virological outcome of a WSSV infection under standardized conditions. Groups of specific pathogen-free Litopenaeus vannamei were challenged either by intramuscular or oral routes with a low (30 SID50) or a high (10,000 SID50) virus titer. Shrimp were kept (i) continuously at 27 °C, (ii) 30 °C or (iii) 33 °C; (iv) maintained at 33 °C before challenge and 27 °C afterwards, or (v) kept at 27 °C before challenge and 33 °C afterwards. Shrimp were maintained at the respective temperatures for 120 h before challenge and 120-144 h post challenge (hpc). Gross signs and mortality were monitored every 12 h until the end of the experiment. Dead and surviving shrimp were screened for WSSV infection (VP28-positive cells) by indirect immunofluorescence (IIF). Shrimp kept continuously at 27 °C or 30 °C, or switched to 27 °C post challenge developed gross signs within 24 hpc, first mortalities at 36-60 hpc and 100% cumulative mortality between 60 and 144 hpc depending on the virus titer. All dead shrimp were WSSV-positive. In contrast, shrimp kept at 33 °C continuously or after WSSV challenge showed no signs of disease and low mortalities (0-30%) regardless of the virus titer. Dead and surviving shrimp were WSSV-negative. Further, early virus replication was studied in two groups of shrimp: one maintained at 27 °C before and after challenge and one switched from 27 °C to 33 °C after challenge with 10,000 SID50. Immunohistochemistry (IHC) analysis showed that WSSV-positive cells were first displayed at 12 hpc in shrimp kept at 27 °C and by 24 hpc the infection became systemic. In contrast, shrimp kept at 33 °C did not display WSSV-positive cells at 12 or 24 hpc. This work confirms previous reports that high water temperature prevents the onset of disease and significantly reduces mortality of WSSV-inoculated shrimp regardless of the route of inoculation or virus titer used. This strategy may have practical applications to control WSSV in tropical shrimp farming countries.  相似文献   

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