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1.
The fatty acid content, fatty acid molecular species composition, and fluidity of phospholipid vesicles and plasma membranes of livers of fish feeding on phytoplankton (silver carp, Hypophthalmichtys molitrix), zooplankton, (big head carp, Hypophtalmitrix nobilis), higher plants, (grass carp, Ctenopharyngodon idella), and omnivorous fish, (common carp, Cyprinus carpio), adapted to reduced temperatures, was determined. Levels of long chain polyunsaturated fatty acids (PUFAs) were highest in silver and big head carp and lowest in common carp. Differences in long chain PUFAs were poorly reflected in fluidity, determined either by fluorescence anizotropy of 1,6-diphenyl 1,3,5-hexatriene or rotational correlation time of 16-doxyl- stearic acid, of phospholipid vesicles. Phospholipid vesicles of C. caripo and C. idella proved to be slightly more rigid than of H. molitrix and H. nobilis below ca. 15 °C. These differences were not seen with isolated plasma membranes assessed with 1,6-diphenyl 1,3,5-hexatriene. Using electron spin resonance spectroscopy plasma membranes from H. molitrix proved to be more fluid than those from C. carpio below ca. 15 °C. Phosphatidylethanolamines were abundant in 1-monounsaturated, 2-polyunsaturated (18:1/22:6, 18:1/20:4) species with H. molitrix and H. nobilis more rich in these species than C. carpio and C. idella. It is suggested that differences in fluidities of phospholipid vesicles below 15 °C is due to differences in levels of the above molecular species. In native membranes these differences may be masked by proteins and other membrane components. It is also suggested that it is not the fatty acid composition of the ingested food but the specific response of the fish to temperature that is the most important factor controlling the physicochemical properties of membranes during thermal adaptation.  相似文献   

2.
Response of fish membranes to environmental temperature   总被引：5，自引：0，他引：5  
The effect of temperature on fluidity, fatty acid and molecular species composition of liver and brain phospholipids in fish adapted or exposed to extreme temperatures was investigated. Membranes from cold-adapted fish were more fluid than those from warm-adapted fish. Ability to control membrane fluidity according to temperature appears in early ontogenesis and is first evident in swim-up fry of carp. Red blood cells as well as neurons of adult carp can continuously adjust the fluidity of their external membranes to changing temperatures. Segregation of choline and ethanolamine phosphoglycerides from livers of fish adapted to a cold/warm environment showed an accumulation of molecular species containing a monoenic fatty acid in position sn-1 and a polyenic fatty acid in position sn-2 of the molecule in cold conditions. Model experiments using mixtures of synthetic 18:1/22:6 phoshatidylethanolamines and 16:0/18:1 phosphatidylcholines demonstrated the involvement of these molecular species in rendering the membranes less packed (more fluid) during adaptation to reduced temperatures.  相似文献   

3.
Formation and deposition of fatty acids in carp maintained on diets differing in total fat as well as linolenic acid content was investigated by following the incorporation of (1-14C)-acetate into liver total- and phospholipid fatty acids at two extreme temperatures (5° and 25°C). Excess dietary linolenic acid was deposited in triglycerides but not in phospholipids. The formation and level of phospholipid docosahexenoic acid was, however, dependent on the amount of linolenic acid in the diet. Despite the vast quantities of ingested linolenic acid, the carp on diets containing sufficient essential fatty acid maintained similar membrane fluidities as judged from the ratio of saturated to unsaturated fatty acids. Decrease of the environmental temperature brought about a reduction in the rate of formation of palmitic acid and an increase in the rate of formation of docosahexenoic acid in carp receiving sufficient essential fatty acid. Consequently, the level of palmitic acid decreased and that of docosahexenoic acid increased in the liver phospholipids in carp and a number of other fish species. Essential fatty acid deficient carp were unable to increase the rate of production of long chain polyunsaturated fatty acids upon exposure to cold. The results are discussed from the point of view of adaptation of membrane fluidity to the temperature by fish, and the importance of docosahexenoic acid in this process is emphasized.  相似文献   

4.
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   

5.
ABSTRACT:   The distribution of zinc (Zn) concentration in the blood and erythrocytes of common carp, grass carp, silver carp and tilapia was studied. It was found that in whole blood, the average Zn concentrations in these four species of fish (approx. 6–14 μg/[ml whole blood]) were relatively similar to those in other species of fish and mammals. However, the mean Zn concentration in the erythrocytes of common carp is approximately two times higher than the other three species of fish (approx. 5 vs approx. 2 μg/[ml whole blood]). It was found that approximately 70% of the Zn in the common carp whole blood came from its erythrocytes. In addition, approximately 43% of the Zn in the erythrocytes of common carp was found to be located on its outer plasma membranes. When an antibody against a 43 kDa Zn-binding protein, isolated from the digestive tract tissue of common carp, was used, significant quantities of the protein were shown to be present on the erythrocyte plasma membranes of common carp by an indirect immunofluorescent staining. High Zn on the outer plasma membrane of the common carp erythrocyte most probably comes from the 43 kDa Zn-binding protein.  相似文献   

6.
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7.
The effects of acclimation temperature and acute temperature change on the uptake and metabolism of the procarcinogen benzo[a]pyrene (BaP) by gill cells of the gulf toadfish, Opsanus beta, were examined. BaP was rapidly accumulated by isolated gill cells and uptake rates were directly proportional to BaP concentration in the medium (1 to 100 μg/ml). Uptake rates were higher in cells isolated from fish acclimated to 18°C when compared to cells from 28°C acclimated fish at all incubation temperatures. When cells were exposed to BaP at the respective acclimation temperatures of the fish, uptake rates were similar (0.14 ± 0.01 at 18°C and 0.12 ± 0.01 μg BaP/s/10 mg cells at 28°C). This finding is discussed in view of results which showed a partial compensation of membrane fluidity in plasma membranes isolated from fish from the two acclimation temperatures. At higher incubation temperatures, cells from fish acclimated to 18°C metabolized BaP at a greater rate than those at 28°C (49.6 ± 1.92 and 43.0 ± 2.24 μg/g/8h, respectively, at 23°C). Low but detectable activities of common biotransformation enzymes (aryl hydrocarbon hydroxylase, glutathione-S-transferase) and cytochrome P-450 content were found, however, no significant differences were evident between cells from fish acclimated to different temperatures. To whom to address correspondence  相似文献   

8.
Malate dehydrogenase isozymes of grass carp,Ctenopharyngodon idella, were identified by mitochondrial preparation and thermal denaturation. The structural and kinetic characteristics of chromatographically separated thermostable and thermolabile cMDHs were different in (1) half-life at 42°C, 10 min and 24 h, respectively, (2) optimal substrate, oxaloacetate and malate, concentrations, and (3) the apparent Michaelis-Menten constants of NADH and oxaloacetate.Total MDH activity in white muscle of 11°C-acclimated fish was about twice that of the 30°C-acclimated group. In addition, the ratio of the thermostable to thermolabile cMDH activity in white muscle of 30°C-acclimated fish was significantly higher than that of 11°C-acclimated fish. These results suggest that temperature acclimation can induce temperature compensation in MDH activity and differential expression of thermostable and thermolabile cMDH isozymes in freshwater fish.  相似文献   

9.
Thermal acclimation may directly modify muscle metabolic capacities, or may modify them indirectly via effects upon physiological processes such as growth, reproduction or senescence. To evaluate these interacting effects, we examined the influence of thermal acclimation and acclimatization upon muscle metabolic capacities and tissue masses in 1 + stickleback, Gasterosteus aculeatus, in which confounding interactions between temperature and senescense should be absent. Furthermore, we examined the influence of thermal acclimation upon individual growth rate, muscle enzyme levels and tissue masses in 2 + stickleback sampled at the beginning of their final reproductive season. For 1 + stickleback, cold acclimation more than doubles mitochondrial enzyme levels in the axial muscle. Thermal acclimation did not change the condition of 1 + stickleback at feeding levels which could not maintain the condition of 2+ stickleback. Compensatory metabolic responses to temperature were not apparent in field acclimatized 1 + stickleback. The growth rate of 2 + stickleback was markedly affected by temperature: warm-acclimated fish generally lost mass even at very high levels of feeding (up to 78 enchytraid worms per day) while cold-acclimated fish gained mass. This suggests that warm temperatures accelerate the senescence of 2 + stickleback. Generally, muscle enzyme activities increased with growth rate. In axial muscle, the relationships between CS activity and growth rate differed with acclimation temperature. Independent of the influence of growth rate, CS activities were consistently higher in cold- than warm-acclimated 2 + stickleback, suggesting compensatory increases of CS activity with cold acclimation. Corresponding author; This paper is dedicated to the memory of Gerry J. FitzGerald who passed away on March 14, 1994.  相似文献   

10.
The temperature dependence of the rates of protein synthesis in the red and white skeletal muscle of the carp (Cyprinus carpio) was measured using a method which involved a single injection of tritiated phenylalanine. Plasma and muscle-free phenylalanine quickly reached a plateau level at all temperatures. During the plateau phase the incorporation of label into protein was liner. Muscle from fish previously acclimated to either a low temperature (8°C) or a high temperature (28°C), showed marked differences in the rates of protein synthesis. The results show that cold acclimation is associated with significantly higher rates of protein synthesis (p<0.001) in both red and white muscle. Arrhenius activation energies, derived from the rates of protein synthesis at the different experimental temperatures, were similar for both red and white muscle in fish acclimated to warm or cold temperatures. Measurements for both acclimated groups over the temperature range 8–34°C showed that the activation energy for the process of protein synthesis was 86.7 kJ/mol and 78.7 kJ/mol for the red and white muscle respectively.  相似文献   

11.
Rainbow trout (Oncorhynchus mykiss) were acclimated to 4 and 18°C and fed at rations levels which led to an equal change in mass at these temperatures during the six week acclimation. Thermal acclimation markedly modified the metabolic organization of red and white muscle. Cold-acclimated fish had activities of -hydroxyacyl CoA dehydrogenase in both red and white muscle that were twice those of warm-acclimated fish. By contrast, the activities of cytochrome oxidase were unchanged by thermal acclimation. Thus, the capacity for -oxidation of lipids is specifically enhanced in the muscle of cold-acclimated trout. In white muscle, citrate synthase and phosphofructokinase activities were also enhanced by cold acclimation (increases of 125% and 35% respectively), while cytochrome oxidase levels were unchanged. The non-parallel changes in the activities of mitochondrial enzymes strongly suggest that trout muscle mitochondria undergo qualitative reorganization during cold acclimation. The relative activities of mitochondrial enzymes suggest that mitochondria from red muscle have a threefold greater capacity to oxidize lipids than those from white muscle.  相似文献   

12.
Fatty acid compositions of both the polar phospholipids (PLs) and the non‐polar neutral lipids (NLs) in fish tissues are influenced by dietary fatty acids, and tissue fatty acid compositions also change during thermal acclimation. The interaction between these factors in governing fatty acid compositions has been little studied, even though this may have importance when fish are reared in cold water. An experiment was conducted to investigate the effects of temperature (2 vs. 8°C), dietary oil source (fish oil vs. vegetable oils) and feed fat content (21% vs. 34% fat) on tissue fatty acid compositions of Atlantic salmon parr. The fish were held in fresh water under a 12 h light:12 h dark photoperiod until they doubled in body mass (from ca. 19 to 38 g, which took ca. 2 months at 8°C and ca. 6 months at 2°C), and then the muscle, viscera and carcass PLs and NLs were analysed for fatty acid composition. The ratios of unsaturated to saturated fatty acids (UFA:SFA), and the unsaturation indices (UIs, the number of unsaturated bonds per 100 fatty acid molecules) were calculated for each lipid class (PL, NL) within each tissue (muscle, viscera and carcass). Both dietary fatty acids and temperature influenced the compositions of the tissue lipids, with the dietary effects being most pronounced. The fatty acid composition of the feed oils was strongly reflected in the NLs of all three tissues, and also had a significant influence on the fatty acid profiles of the PLs. The effects of temperature were more marked in the PLs than in the NLs. Exposure to the lower temperature resulted in PLs with higher UFA:SFAs, and this is interpreted as a thermal acclimation response that would contribute to the maintenance of membrane fluidity. The PLs of fish given vegetable oils had higher UFA:SFAs than those of salmon provided with feeds containing fish oil, implying that the cell membranes of the former may have had greater fluidity. By contrast, the PLs of salmon fed with fish oil had higher concentrations of n‐3 highly unsaturated fatty acids, and higher UIs, which may have made them more prone to peroxidative damage. This raises the intriguing possibility that the feeding of vegetable oils may have produced fish that were better able to withstand exposure to low temperature as a result of improved membrane fluidity (implied from the higher UFA:SFAs in these fish), while having membrane PLs that were less susceptible to oxidative damage (implied from the lower UIs).  相似文献   

13.
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14.
Cryopreservation of semen collected from dead fishes showed that it is possible to use it for fish production. We humanely killed individuals of the Indian major carp rohu, Labeo rohita and stored at different temperature regimes of 31 °C, 0 °C, − 10 °C and − 30 °C till 8 h. At every one hour interval semen from these fishes were collected by Pasteur pipette and evaluated for sperm yield/kg body weight, motility, pH, spermatocrit (%) and sperm count. The semen having suitable characteristics such as; 70% spermatocrit or above and motility index of 4 or above was cryopreserved by following a specific protocol. The cryopreserved semen of the dead fishes was stored for 7 days and then thawed in a water bath at 37 °C for 50 s. It was found that up to 8 h, spermatozoa of rohu were viable when stored at 0 °C or − 10 °C. Sperm collected after 8 h of fish death and maintained at 0 °C was the best stored condition that showed 30% larval survival. The spermatozoa collected 8 h after fish death was mostly normal as observed under scanning electron microscope and the total length of rohu spermatozoa was 25-30 μm. The hatchlings produced with this cryopreserved semen grew normally and juvenile fishes of rohu could be produced. This study suggests that germ cells such as spermatozoa of dead fishes can be cryopreserved and utilized for restoration of a species. It has the potential use in cryo-conservation of endangered fishes, restoration of animals through fertilization and genetic manipulation studies.  相似文献   

15.
The study explored the effects of ethyl ether extract, ethyl acetate extract (EAE), acetone extract, ethanol extract and aqueous extract of Angelica sinensis (EAs) and ethoxyquin (EQ) on lipid oxidation in erythrocytes and growth, digestive, absorptive and antioxidant capacity in carp (Cyprinus carpio var. Jian). The results indicated that EAs and EQ respectively at the concentrations of 0.5 and 0.25 mg/ml suppressed lipid oxidation by decreasing the generation of ROS and restoring the activities of antioxidants in hydroxyl radical‐treated erythrocytes. Of all of the examined EAs, EAE showed the strongest protective effects against lipid oxidation in carp erythrocytes. The antioxidant effects of EQ at the concentration of 0.25 mg/ml were stronger than that of EAE at the concentration of 0.5 mg/ml in fish erythrocytes. The antioxidative activities of EAs in carp erythrocytes were positively correlated with their phenols content. Moreover, dietary EAE raised growth performance in fish. The appropriate concentration of EAE for the growth of fish was estimated to be 3.544 g/kg diet. Dietary EAE increased digestive and absorptive capacity in carp and improved antioxidant capacity in copper‐treated carp. So, EAE could be used as a potential natural antioxidant and inhibitor of copper stress in fish.  相似文献   

16.
Three case studies of ammonia autointoxication of the common carp (Cyprinus carpio L.) are described. In the first case, carp yearlings with a full digestive tract were transferred during the growing period from pond water (22°C) to tap water (17°C). In the second case, marketable carp were transferred from the fishing ground of a pond (18°C) to a storage pond (10–12°C). Harvest was performed in late September when the fish were still ingesting natural feed. In the third case, marketable carp after storage for 1 month were transferred to storage ponds with markedly lower water temperature. Stress because of harvest and handling also occurred in this case. In all cases, highly increased concentrations of ammonia were found in the blood plasma of the fish (mean ± SD 1760 ± 350 μmol L−1 in the first case, 870 ± 540 μmol L−1 in the second case, and 880 ± 150 μmol L−1 in the third case). Highly congested, dark-red coloured, oedematous gills were observed for all specimens. We can avoid similar cases of ammonia autointoxication by protection of fish from sudden changes of temperature during rearing, harvesting, and handling.  相似文献   

17.
In a temperate climate the survival of carp larvae is limited by the pronounced cooling that usually occurs in the period of early stages of larval development, i.e. during the late spring. On the basis of previously obtained results it was assumed that years favourable for the survival of juvenile carp occur when the water temperature in the pond decreases from about 20 °C to about 14 °C more than 10 days after pond stocking. The unfavourable years are those with a temperature decrease occurring earlier. In a shallow nursery pond the cooling causes severe temperature drops that can create lethal conditions for the carp larvae. The frequent temperature decreases encouraged the seeking of carp strains and crossbreeds resistant to such changes. Polish, Hungarian, and French strains and also crossbreeds between them were considered. Under favourable thermal conditions the crossbreeds and strains showed distinctly higher average survival (p = 0.086). In each year the survival rate of the crossbreeds was higher (p = 0.013) although there was a pronounced variability in the survival rate of all breeds and crosses.  相似文献   

18.
Feed intake, specific growth rate and changes in body composition of age 1+ and 2+ Baltic salmon, Salmo salar L, were studied for fish held under constant temperature conditions. The 1+ fish (60 g) were reared for 6 weeks at 11, 15, 17, 19 or 23 °C and 2+ fish (250 g) were held at 15 °C. Feed intake of 1+ salmon increased from 176 kJ kg-1 day-1 at 11 °C to 275 kJ kg-1 day-1 at 17 °C and decreased to 229 kJ kg-1 day-1 at 23 °C. Specific growth rate increased from 1.18% day-1 at 11 °C to 1.59% day-1 at 15 °C and decreased to 0.56% day-1 at 23 °C. Optimum temperatures for feed intake and growth were estimated at 17.8 °C and 15.6 °C, respectively, and estimated upper thermal limits for feeding and growth were 29.0 °C and 24.1 °C, respectively. Models for feed intake and growth rate in relation to temperature and fish size are presented. The utilization efficiency of ingested energy decreased from 57% at 11 °C to 22% at 23 °C. For all groups of 1+ fish, most (approximately 86%) of the weight gain consisted of water. Lipid deposition accounted for about 52% of the body energy gain irrespective of rearing temperature.  相似文献   

19.
硬酯酰辅酶A脱氢酶(Stearoyl-CoA Desaturase,SCD)是参与脂肪酸脱氢反应的限速酶和关键酶,此酶编码基因SCD对增加膜磷脂的不饱和脂肪酸成分,提高细胞膜在低温下的流动性发挥重要作用,可能是抗寒过程中的关键基因成员。本研究采用cDNA末端快速扩增技术(Rapid Amplifications of cDNAEnds,RACE)克隆了鲤(Cyprinus carpio)脑组织CcSCD基因的全长cDNA序列,采用实时荧光定量PCR技术检测该基因在低温(6℃)和常温(23℃)条件下的转录表达差异,对其蛋白编码序列的结构和功能进行了预测分析。结果显示,CcSCD基因cDNA全长2618bp,包含一个由324个氨基酸残基组成的长度为975bp的阅读框(ORF);蛋白分子进化树显示鲤的SCD和草鱼(Ctenopharyngodon idella)的SCD蛋白同源性最高,相似性达88%;实时荧光定量结果表明,低温刺激下(6℃),CcSCD基因表达水平是常温条件下(23℃)的13.9倍,差异非常显著(P0.01)。本研究旨在为今后构建表达载体,通过遗传操作等研究手段鉴定其抗寒功能奠定基础。  相似文献   

20.
ABSTRACT: Transglutaminase seems to be related to the setting phenomenon of fish meat paste that occurs at temperatures below 40°C. In many reports on the relationship between transglutaminase and setting phenomenon, the enzyme activity has been measured at 25°C. However, it is known that the setting phenomenon is complicated and the effect of calcium and the 3-D structure of myofibrils, which are sensitive to temperature, play important roles in the reaction. In the present study, total activities of transglutaminase of threadfin bream, white croaker, red sea bream and carp meats were measured at various temperatures. Total transglutaminase activities at 25°C of tested fish meats are arranged in order as follows; white croaker, red sea bream, carp, threadfin bream. In contrast, optimal temperature of carp meat is 30°C, red sea bream 40°C, threadfin bream 50°C and white croaker 50–55°C. In carp meat, the enzyme activity at optimal temperature (30°C) became 8.5-fold higher than at 25°C. The data of the total activity at various temperatures are useful in order to comprehend the details of the reaction.  相似文献   

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