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应用对比试验和正交试验方法对草鱼进行酶解技术研究。试验结果表明,胃蛋白酶酶解草鱼酶用量为(E/S)0.6%,温度55℃,pH2.0,酶解5h氨基态氮含量较高,为0.0190g/L;枯草杆菌蛋白酶酶解草鱼酶用量为(E/S)0.01%,温度45℃,pH6.5,酶解4h氨基态氮含量较高,为0.0417g/L;胰蛋白酶酶解草鱼酶用量为(E/S)0.64%,温度50℃,pH8.0,酶解5h氨基态氮含量较高,为0.0472g/L。通过对3种蛋白酶在最优条件下酶解草鱼肉的比较可知,枯草杆菌蛋白酶和胰蛋白酶酶解效果较好。为草鱼深加工提供了一定的科学依据。 相似文献
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鲢酶解物对羟自由基的清除作用 总被引:29,自引:0,他引:29
通过测定酶解物对Fenton体系产生的羟自由基的清除效果,从胰蛋白酶、木瓜蛋白酶、胃蛋白酶、枯草杆菌蛋白酶和复合蛋白酶5种酶中,筛选出木瓜蛋白酶和胰蛋白酶作为酶解鲢制备具有较高清除羟自由基活性酶解物的理想水解酶;用正交试验L9(3^4)对两种酶的水解条件进行了优化,并对最佳酶解条件下得到的酶解物进行Sephadex G-25凝胶柱分离,洗脱液分别在波长280nm处比色,测定酶解物中主要抗氧化活性肽的分子量分布。结果表明,木瓜蛋白酶在温度50℃、酶解时间15min、pH=6.5、酶质量分数1.50%、底物:水=1:2的水解条件下,酶解物对羟自由基清除效果较好,清除率为88.2%;胰蛋白酶在温度55℃、酶解时间60min、pH=8.0、酶质量分数0.25%、底物:水=1:2的水解条件下,酶解物对羟自由基清除效果较好,清除率为84.2%。木瓜蛋白酶酶解物在最大洗脱峰时有最大羟自由基清除率峰,清除率为95.1%,在最大峰处酶解物中活性肽的分子量为2.2kDa;胰蛋白酶酶解物在最大洗脱峰时也有最大羟自由基清除率峰,其清除率为89.6%,该峰处活性肽的分子量为14.2kDa。 相似文献
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低值鱼酶解蛋白的制取及其组成研究 总被引:21,自引:0,他引:21
研究了复合生物酶酶量,酶解时间,酶解温度等对低值鱼蛋白酶解效果的影响。研究结果表明,酶浓度提高,水解时间延长,均明显提高低值蛋白水解率,复合生物酶最适水解温度为50℃,温度高于50℃,水解率逐渐下降,苦味值随水解率提高而增加,综合考虑,该复合生物酶水解低值鱼的最佳条件为;酶量与底物之比:1.5:1000;温度:50℃,水解时间:4h,复合酶水解低值鱼蛋白经氨基酸分析仪检测,其氨基酸含量为73%,经高效液相色谱分析,其分子量组成范围在7400以下,其中3000以下占90%以上,1000以下的占54%。 相似文献
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牡蛎酶解工艺条件的研究 总被引:13,自引:0,他引:13
比较选择了牡蛎酶解的有效蛋白酶,研究了牡蛎酶解的工艺中各主要因素对提取率的影响。结果表明,A.SI,398枯草芽跑杆菌中性蛋白酶和胰蛋白酶对牡蛎有较好的酶解效果。酶解温度、加酶量、底物浓度对酶解提取率影响较大。确定了牡蛎酶解的最佳工艺条件为:酶解温度50℃;加酶量0.5%;底物浓度6%;酶解时间2h。 相似文献
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翘嘴红鲔胃、肠道及肝胰脏主要消化酶活力的研究 总被引:1,自引:0,他引:1
对翘嘴红舶胃肠道及肝胰脏的淀粉酶、脂肪酶、蛋白酶3种主要消化酶活力进行初步研究。结果表明:胃、肠道、肝胰脏的淀粉酶的最适pH均为6.0;脂肪酶的最适pH分别为8.0、8.0、7.5;胃蛋白酶最适pH为2.0,肠道、肝胰脏蛋白酶的最适pH分别为7.0、7.5。同时研究了在最适pH条件下,不同反应温度对3种主要消化酶的活性影响。结果表明:翘嘴红刍白淀粉酶在肝胰脏、肠道、胃的最适温度分别为30℃,30℃,25℃;脂肪酶的最适温度分别为40℃,30℃,35℃;蛋白酶的最适温度分别为50℃,50℃,40℃。在一定的温度范围内,3种消化酶的活力均呈先上升后下降趋势。最适反应温度下翘嘴红自自脂肪酶与淀粉酶的活力分布均呈现肝胰脏〉肠道〉胃,蛋白酶活力肠道与胃接近,大于肝胰脏蛋白酶活力。 相似文献
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Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean 下载免费PDF全文
The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna. 相似文献
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In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg. 相似文献
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Sandra García‐Garrido Ismael Hachero‐Cruzado Carlos Rosas Pedro Domingues 《Aquaculture Research》2013,44(11):1741-1751
Protein and amino acid composition of the mantle of juvenile O ctopus vulgaris (Cuvier, 1797) during fasting for 27 days were determined. Average protein content of octopus mantle was of 711.19 ± 46.80 g kg?1 DW, and it decreased with increasing fasting days. The non‐essential amino acids content was higher (486.18 ± 11.08 g kg?1 protein) than essential amino acids (425.82 ± 9.15 g kg?1 protein) at the start of the experiment (unstarved animals). The results suggest that the amino acid profile of the mantle where the most abundant amino acids are Arg, His, Lys, Gly, Leu and Pro could indicate a prolonged fasting condition (>20 days) or poor nutrition of O . vulgaris. This study supports the idea of using mantle for metabolic needs of starved O . vulgaris suggesting that the degradation pathway of amino acids to pyruvate and tricarboxylic acid cycle intermediates was favoured contrary to the degradation pathway of ketogenic amino acids. Special considerations should be taken concerning Thr, Ile, Ser, Ala, Asx (Asp, Asn), Glx (Glu, Gln) (because of their fast intake) and Lys and His (due to their stable contents) during a prolonged period of fasting. 相似文献
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William King V David L. Berlinsky Craig V. Sullivan 《Fish physiology and biochemistry》1995,14(6):489-500
Plasma estradiol-17 (E2), testosterone (T), 17,20-dihydroxy-4-pregnen-3-one (DHP) and 17,20,21-tri-hydroxy-4-pregnen-3-one (20-S) levels were measured by radioimmunoassay (RIA) in white perch (Morone americana) and white bass (M. chrysops) that were induced to undergo final oocyte maturation (FOM) with human chorionic gonadotropin (hCG). Plasma DHP levels increased in females of both species in association with oocyte germinal vesicle migration (GVM) and germinal vesicle breakdown (GVBD) and decreased thereafter. Plasma 20-S levels also increased with oocyte GVM in white bass, but were several-fold lower than DHP levels. Circulating E2 and T levels were greatest during GVM and GVBD in both species and decreased to low levels during oocyte hydration and ovulation. Follicles from white perch and white bass which received a priming injection of hCG in vivo, produced both DHP and 20-S in vitro after exposure to hCG and their oocytes underwent GVBD. Ovarian incubates from unprimed fish of either species produced only E2 and T and their oocytes did not complete GVBD. Oocytes from unprimed bass, but not perch, matured when follicles were exposed to hCG in vitro. Both trilostane and cycloheximide blocked in vitro production of DHP and 20-S and oocyte GVBD by white perch follices. DHP and 20-S were equipotent inducers of FOM in the GVBD bioassay. None of several other structurally-related steroids tested were effective within a physiological range of concentrations. These results indicate a role for DHP and 20-S in the control of FOM in white perch and white bass. 相似文献
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Cardiac,ventilatory and metabolic responses of two ecologically dissimilar species of fish to waterborne cyanide 总被引:1,自引:0,他引:1
Changes in heart rate, ventilatory activity and oxygen consumption were determined in trout (Salmo gairdneri) and brown bullhead catfish (Ictalurus nebulosus) during exposure to a steadily increasing concentration of waterborne cyanide selected to produce death in 8–9 hours for each species. The lethal cyanide concentration for the bullheads was an order of magnitude higher than for trout. Trout developed an immediate and gradually increasing bradycardia throughout the exposure period. Cyanide produced tachycardia in the bullhead followed by a gradual onset of bradycardia as the concentration of cyanide was raised. Pericardial injection of atropine (a muscarinic cholinergic antagonist) indicated that bradycardia in the trout was due initially to increased vagal tone but later due to the direct effect of cyanide on the heart. Hyperventilation in the trout persisted throughout the exposure period, although the rate and amplitude fluctuated and was variable between individual fish. During the last hour of exposure (highest cyanide concentration), ventilation was characterized by rapid, shallow breaths followed by a sudden respiratory arrest. The bullheads exhibited hyperventilation during the first 3 hours of exposure followed by a gradual, linear drop in ventilation rate and amplitude until death occurred. Cardiac and ventilatory responses in both species were attributed to stimulation of central and peripheral chemoreceptors by cyanide. Evidence is presented which suggests the initial response in the bullheads was due, at least in part, to gustatory stimulation by the cyanide. Oxygen consumption of the trout remained above pre-exposure levels for the majority of the test period. Oxygen consumption in the bullhead paralleled the changes in heart and ventilatory rates. Whole-body lactate levels of fingerlings of both species during cyanide exposure were measured to estimate the extent of anaerobiosis. Whole-body lactate levels were much greater in the bullheads than the trout, indicating a higher capacity for anaerobiosis, possibly due to a greater fuel supply. Overall, the trout responded to cyanide in a manner similar to that produced by environmental hypoxia whereas the bullheads experienced a gustatory stimulus which masked the hypoxia-like response. 相似文献
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An overview of stress physiology of fish transport: changes in water quality as a function of transport duration 下载免费PDF全文
This study brings an integrated analysis about the relationship between water deterioration and its physiological consequences in live fish transport. The analysis was focused on the transport water and its deterioration, and physiological challenges imposed on the fish. Usual commercial handling procedures employed to mitigate fish stress during transport were discussed. Future topics of research for the establishment of safer fish transport protocols were proposed. Transport was classified into short (≤8 h) or long transport (>8 h). The main issue in short transports should be the prevention of water pH reduction, while in long transports it is the increase in ammonia. Plasma cortisol is the most employed marker for stress and is acutely elevated upon short episodes of transport, but remains elevated even in long‐transport events. Plasma glucose is perhaps a better marker for handling stress. Plasma lactate, pH, osmolality CO2 and ions should be more often evaluated. Plasma Na+ and Cl‐ are very useful markers of acidosis, due to their respective exchange for H+ and , for acid–base regulation. The establishment of species‐specific transport protocols should be preceded by such combined analyses of water and physiological parameters. 相似文献
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Are hatchery‐reared abalone naïve of predators? Comparing the behaviours of wild and hatchery‐reared northern abalone,Haliotis kamtschatkana (Jonas, 1845) 下载免费PDF全文
Abalone populations have declined worldwide, generating interest in enhancement using hatchery‐reared individuals. In many cases, such restoration efforts have met with limited success due to high predator‐induced mortality rates. Furthermore, the mortality rates of outplanted hatchery abalone are often considerably higher than for wild individuals. This study uses northern abalone (Haliotis kamtschatkana) as a case study to determine whether hatchery‐reared abalone behave differently than their wild counterparts. In the field, outplanted hatchery‐reared abalone were significantly less responsive than wild abalone, in terms of number of abalone responding and intensity of response, to nearby movement and to physical contact with an inert probe. Also, when encountering a cue to which all abalone responded (a seastar predator), hatchery‐reared individuals remained subdued. Anti‐predator behavioural deficits in hatchery‐reared abalone were more pronounced in 4‐year‐old individuals than in 1‐year‐old individuals, suggesting an influence of either age or amount of time spent in the hatchery environment. These behavioural differences are expected to increase the vulnerability of hatchery‐reared abalone to predators, and are likely a major cause of their elevated predator‐induced mortality when outplanted. 相似文献
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The toxic effects of Cd2+ on Ca2+ influx kinetics in developing tilapia (Oreochromis mossambicus) larvae were evaluated. Addition of 20 µg l-1 of Cd2+ to the environment of 0 and 3 day-old larvae competitively inhibited the Ca2+ uptake within 4h resulting in a great increase in Km values for Ca2+ influx (19.3 and 17.4 fold, respectively) as compared with their respective controls. Consequently, the actual Ca2+ influx of larvae in solutions of 0.2 mM Ca2+ are suppressed by 32–45%. Also, 3 day-old larvae were more sensitive to internally accumulated Cd2+ than 0 day-old larvae. Although the Ca2+ influx in 0 and 3 day-old larvae may be restored to the levels of their respective controls with 24h of being transferred to a 20 µg l-1 Cd2+ solution, total body Ca2+ content was significantly reduced in 3 day-old larvae. Increased Ca2+ uptake efficiency ensures sufficient Ca2+ for normal growth. However, rapid increase in Ca2+ influx after hatching also leads to higher Cd2+ uptake. Exposure to Cd2+ will lead to a drop in body Ca2+ content resulting in retardation of larval growth. Therefore, we conclude that if Ca2+ uptake is interfered with at this critical stage of development, larvae will not be able to maintain normal levels of body Ca2+ and will show signs of Cd2+ poisoning. 相似文献
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Abstract– Literature evidence suggests that lake-dwelling longnose gar (Lepisosteus osseus) enter tributary streams to spawn, Until the present study, the dynamics of this breeding migration had never been investigated quantitatively. During the summers of 1991 and 1992, longnose gar were captured as they entered Weaubleau Creek, Missouri, a tributary of Harry S. Truman Reservoir. The in-stream spawning migration began in early April and ended in late May, and was positively correlated with stream flow and water level, and negatively correlated with water temperature. In-stream residence times ranged from 15 to 94 days, with males exhibiting longer residence times than females. Once in-stream, longnose gar travelled as far as 10 km upstream and occupied certain pools at greater relative frequencies. Although the reason for this preferential utilization is not completely understood, it may relate to pool depth and riffle proximity. Longnose gar disperse from the spawning stream great distances, with gar captured in Weaubleau Creek being recaptured up to 48 km away. This information should provide fisheries biologists the means to consider the reproductive ecology of this species in their conservation and management decisions. 相似文献
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D.R. Tocher M. Agaba N. Hastings J.G. Bell J.R. Dick A.J. Teale 《Fish physiology and biochemistry》2001,24(4):309-320
The desaturation and elongation of [1-14C]18:3n-3 was investigated in hepatocytes of the tropical warm freshwater species, zebrafish (Danio rerio) and Nile tilapia (Oreochromis niloticus). The hepatocyte fatty acid desaturation/elongation pathway was assayed before and after the fish were fed two experimental
diets, a control diet containing fish oil (FO) and a diet containing vegetable oil (VO; a blend of olive, linseed and high
oleic acid sunflower oils) for 10 weeks. The VO diet was formulated to provide 1% each of 18:2n-6 and 18:3n-3, and so satisfy
the possible EFA requirements of zebrafish and tilapia. At the end of the dietary trial, the lipid and fatty acid composition
was determined in whole zebrafish, and liver, white muscle and brain of tilapia. Both zebrafish and tilapia expressed a hepatocyte
fatty acid desaturation/elongation pattern consistent with them being freshwater and planktonivorous fish. The data also showed
that hepatic fatty acid desaturation/elongation was nutritionally regulated with the activities being higher in fish fed the
VO diet compared to fish fed the FO diet. In zebrafish, the main effect of the VO diet was increased fatty acid Δ6 desaturase
activity resulting in the production of significantly more 18:4n-3 compared to fish fed the FO diet. In tilapia, all activities
in the pathway were greater in fish fed the VO diet resulting in increased amounts of all fatty acids in the pathway, but
primarily eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3). However, the fatty acid compositional
data indicated that despite increased activity, desaturation of 18:3n-3 was insufficient to maintain tissue proportions of
EPA and DHA in fish fed the VO diet at the same level as in fish fed the FO diet. Practically, these results indicate that
manipulation of tilapia diets in commercial culture in response to the declining global fish oil market would have important
consequences for fish fatty acid composition and the health of consumers. Scientifically, zebrafish and tilapia, both the
subject of active genome mapping projects, could be useful models for studies of lipid and fatty acid metabolism at a molecular
biological and genetic level.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献