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1.
鲢鱼糜凝胶形成过程中化学作用力及蛋白质构象的变化 总被引：5，自引：0，他引：5
采用化学法、激光拉曼光谱、圆二色谱等先进的现代检测分析手段,研究鲢（Hypophthalmichthys molitrix）鱼糜凝胶形成过程中离子键、氢键、疏水相互作用、二硫键、非二硫共价键等化学作用力对鱼糜凝胶形成的作用,并对蛋白质构象进行了表征,探索化学作用力及蛋白质构象对鲢鱼糜凝胶网络结构形成的作用。结果表明,在鱼糜凝胶形成过程中,离子键、氢键显著减少,而疏水相互作用、二硫键、非二硫共价键显著增加。疏水相互作用、二硫键、非二硫共价键是维持鲢鱼糜凝胶稳定结构的主要化学作用力。40℃和90℃两段加热过程中,鲢肌球蛋白的α-螺旋结构部分转变成转角和无规卷曲结构,以无规卷曲结构为主。鲢鱼糜凝胶中肌球蛋白的二级结构单元α-螺旋、转角、无规卷曲结构的百分含量分别为33．70％、12．40％、53．90％,其中α-螺旋和无规卷曲结构是维持鲢鱼糜凝胶网络结构的主要蛋白质构象。维持鲢鱼糜凝胶稳定结构的主要化学作用力为疏水相互作用、二硫键、非二硫共价键,主要蛋白质构象为α-螺旋和无规卷曲结构。[中国水产科学,2008,15（3）：469-475] 相似文献
2.
鳊鱼鱼糜蛋白质结构与凝胶特性关系的研究 总被引：1，自引：1，他引：0
蛋白质对于鱼糜凝胶形成具有重要作用,通过研究鳊鱼鱼糜贮藏过程中肌球蛋白化学作用力、激光拉曼光谱等的变化探讨蛋白质结构对鱼糜凝胶形成的影响。结果发现,鱼糜在-80℃、-20℃冻藏过程中,肌球蛋白含量、离子键、氢键与疏水相互作用含量呈现先快后慢的二段式下降趋势,与其凝胶强度变化趋势一致;在0℃和5℃贮藏过程中,肌球蛋白含量、离子键和氢键含量呈不断下降的趋势,与凝胶强度变化趋势基本一致,而疏水相互作用为先增加后减少,由此可见,肌球蛋白含量、离子键和氢键含量在维持鱼糜蛋白高级结构上起着重要的作用。激光拉曼光谱结果显示α-螺旋结构是维持鳊鱼糜蛋白质网状结构的主要构象,在贮藏过程中,部分α-螺旋结构转变成无规卷曲,使包埋于肌球蛋白分子内的疏水性残基暴露于分子表面,进而发生蛋白变性;贮藏温度越高,无规卷曲结构越多,蛋白变性程度越大,表现在凝胶强度降低越多。鱼糜贮藏过程中蛋白质结构变化的研究对于阐明鱼糜凝胶形成机理和防止鱼糜蛋白变性具有一定意义。 相似文献
3.
大豆胰蛋白酶抑制剂对鲢丝氨酸蛋白酶的作用 总被引：1，自引：0，他引：1
研究了大豆胰蛋白酶抑制剂(STI)对鲢肌肉中肌原纤维结合型丝氨酸蛋白酶(MBSP)引起的肌原纤维蛋白降解作用的影响。大豆胰蛋白酶抑制剂经高度纯化后加入肌原纤维中以判断它对MBSP的抑制效果。在不添加STI的情况下,55℃加热30min即可观察到肌球蛋白重链的分解,延长加热时间则可检测到肌动蛋白及原肌球蛋白的降解。相反,在终浓度为0.75μg·mL-1的STI存在下,包括肌球蛋白重链在内的肌原纤维蛋白降解均能得到有效抑制,表明STI是MBSP的特异性抑制剂。由于肌球蛋白重链及肌动蛋白的完整性是构成鱼糜制品凝胶强度的主要因素,因此,STI的添加有可能提高鲢鱼糜制品的凝胶强度。 相似文献
4.
为了比较4种变性淀粉与商业抗冻剂(4%蔗糖+4%山梨醇)对鲢鱼糜在冻结过程(-20、-80℃下静止冻结)中的影响,对冻结速率、冻结相变热特性参数、凝胶强度和持水性能进行了测定。结果表明,鱼糜在-80℃下的冻结速率均显著高于-20℃下;同一冻结温度下,几种添加物均会降低鱼糜的冻结速率及冻结相变焓,而提高冷冻鱼糜凝胶的持水性能,且变性淀粉组的持水性都显著高于商业抗冻剂组(P0.05)。在-80℃冻结时,添加交联酯化淀粉与醋酸酯化淀粉的鱼糜的冻结速率相近,且均显著小于其他组(P0.05)。在2种冻结温度下,醋酸酯化淀粉组的凝胶强度均与商业抗冻剂组无显著性差异,而显著高于其他实验组(P0.05)。研究表明,4%蔗糖+4%醋酸酯化淀粉可有效地防止鱼糜在冻结过程中的品质变化,可代替商业抗冻剂应用在冷冻鱼糜中。 相似文献
5.
羟丙基二淀粉磷酸酯对虾糜凝胶特性及其蛋白结构的影响 总被引：1，自引：0，他引：1
为考察羟丙基二淀粉磷酸酯（hydroxypropyl distarch phosphate, HPDSP）对中华管鞭虾Solenocera melantho虾糜凝胶性能的改善效果，在虾糜中分别添加1%、3%、5%、7%、9%的HPDSP，以凝胶强度、质地剖面分析、持水性、凝胶微观结构等为指标，并提取虾糜溶胶、凝胶化虾糜、虾糜凝胶中的肌原纤维蛋白，通过圆二色光谱分析蛋白分子二级结构，探究HPDSP对虾糜凝胶性能的影响及其机理。结果表明：添加HPDSP能提高虾糜凝胶的凝胶强度和持水性，并在添加量为7%时达到最大值；HPDSP使虾糜凝胶a*值和b*值下降，但L*值和白度除9%添加量组外，均没有显著变化；适量HPDSP能提高虾糜凝胶硬度、弹性、粘聚性和咀嚼性，促进虾糜形成更加致密稳定的凝胶网状结构。在虾糜凝胶化过程中，加热引起肌原纤维蛋白的α-螺旋含量降低，β-折叠和无规卷曲含量升高，同时HPDSP会对肌原纤维蛋白热变性和聚集产生影响，从而改变其二级结构，影响虾糜凝胶的形成。结论：在中华管鞭虾虾糜中，添加7%的HPDSP能显著改善虾糜凝胶性能。 相似文献
6.
以夏季和冬季鲢为研究对象,利用胰凝乳蛋白酶能水解羧基端含芳香族氨基酸残基肽键的特性,根据其特异性酶切部位,结合电泳手段来分析肌球蛋白的内部构造差异性。结果表明,与夏季样品相比,冬季鲢的肌原纤维蛋白经酶切生成的肌球蛋白头部S-1较长,在高温下分子量为165 ku的重酶解肌球蛋白HMM容易被再降解成小片段的135 ku HMM,呈现出冬季肌球蛋白的结构不稳定性。在不同温度下加热夏季和冬季肌球蛋白,其ATPase失活速度和酶解肌球蛋白生成S-1的产生量的减少速度呈现一致性,说明酶解生成的S-1只来源于有活性的肌球蛋白。同时,冬季肌球蛋白热变性温度较夏季肌球蛋白要低6 ℃,表明冬季肌球蛋白的不稳定性。 相似文献
7.
加热对远东拟沙丁鱼鱼糜制品质量的影响 总被引：1，自引：0，他引：1
本文对沙丁鱼鱼糜就不同的加热方法初步探讨了其最佳加热条件,采用了新的压出水分指标(Ip-A)方法评价鱼糜制品的保水性,讨论了加热方法和保水性的关系,并测定了鱼糜加热前后肌球蛋白的变化。结果表明:以 30℃ 120分钟、90℃ 30分钟和 40℃ 20分钟、90℃ 30分钟的加热方法,鱼糜制品的质量为好;60℃是远东拟沙丁鱼鱼糜的凝胶劣化温度。压出水分(Ip-A)与凝胶强度呈线性负相关(r=-0.9649);在30℃和40℃的凝胶化温度下,肌球蛋白残留量迅速下降.而在60℃加热时,下降反而缓慢;在90℃加热时,肌球蛋白的残留量与加热时间的对数呈线性负相关(r=-0.9957)。 相似文献
8.
漂洗条件对鲢糜凝胶强度的影响 总被引：9，自引：0，他引：9
研究了漂洗次数,漂洗液ＰＨ、漂洗液种类等因素对鲢糜凝胶强度的影响,漂洗次数越多,漂洗液ＰＨ在中性,用柠檬酸钠溶液和ＣａＣｌ２溶液进行漂洗时,可有效提高鱼糜制品的凝胶强度。 相似文献
9.
圆苞车前子壳粉(psyllium husk powder, PHP)是一种富含膳食纤维的食品亲水胶体。为了解其在鱼糜制品中的作用,本实验以冷冻鲢鱼糜为研究对象,以凝胶强度和持水性(water holding capacity, WHC)为考察指标,研究了PHP的添加量、凝胶化温度和凝胶化时间3个因素对鱼糜凝胶特性的影响。在单因素试验的基础上,进行了三因素三水平的正交试验和验证试验。正交试验结果得到最佳工艺条件:PHP添加量0.1%,凝胶化温度45°C,凝胶化时间2 h。单因素试验结果表明,添加适量PHP (0.1%～0.3%)能够增加鱼糜凝胶的硬度和WHC,但对破断距离有不利影响;根据验证试验中蒸煮损失率、SDS-聚丙烯酰胺凝胶电泳(SDS-polyacrylamide gel electrophoresis, SDS-PAGE)和扫描电镜(scanning electron microscopy, SEM)分析,PHP的添加降低了较高凝胶化温度时凝胶的蒸煮损失,PHP或许可以促进肌球蛋白重链(myosin heavy chain, MHC)分子间交联,减缓蛋白质降解,形成更加致密的凝胶结构。本研究对PHP作为一种新型食品原料应用于开发优质健康鱼糜制品进行了初步的探究,以期为丰富亲水胶在影响鱼糜凝胶特性中的应用研究提供一定的参考。 相似文献
10.
鲢鱼骨胶原多肽螯合钙的制备研究 总被引：1，自引：0，他引：1
文章探讨了以鲢（Hypophthalmichthysmolitrix）鱼骨为原料,采用风味蛋白酶酶解制备骨胶原多肽水解液,剩余骨渣经乳酸提取制备骨粉酸解液（钙液）,研究其通过螯合制备鲢鱼骨胶原多肽螯合钙的工艺条件。分析了酶解时间对鲢鱼骨蛋白酶解产物产品品质和功能特性（溶解性和热稳定性）的影响以及采用乳酸提取鲢鱼骨中钙时提取温度对钙溶出率的影响,并以螯合率为指标,考察pH、时间、温度和多肽液与钙液体积比对螯合反应的影响。结果表明,在温度50℃,按原料鱼排质量0．09％加入风味蛋白酶酶解30min制备出的鲢鱼骨胶原多肽具有良好的产品品质和功能特性;乳酸提钙时提取温度对钙溶出率没有显著性影响（P〉0．05）;在pH8、温度25℃条件下,多肽液与钙液体积比1：1反应40min得到的鲢鱼骨胶原蛋白螯合钙螯合率最高（85．24％）。 相似文献
11.
Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean 
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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
12.
Liping Li Rui Wang Wanwen Liang Xi Gan Ting Huang Yan Huang Jian Li Yunliang Shi Honglin Luo Ming Chen 《广西水产科技》2014,(1)
Previously, we reported 10 PEGE types of 85 tilapia Streptococcus agalactiae(GBS), which shifted from Streptococcus iniae in China, by using PEGE method. Presently, larger and more representative tilapia GBS were isolated, for the ?rst time in China, to characterize their serotypes and genetic diversities more precisely than had done before. 168 GBS strains were distributed in ?ve provinces of China, in which Guangdong, Guangxi and Hainan were the major ones, holding36.9%(62/168), 37.5%(63/168) and 19.6%(33/168), respectively. Serotypes, Ia, Ib and III, were observed in these strains and the most predominant one was Ia(95.2%), which mainly distributed in Guangdong, Guangxi and Hainan. Ia initially occurred in 2009, it shoot up to 32.1% in 2010,but decreased to 16.1% in 2011 before went up to 45.2% in 2012. Ib sporadically occurred during2007–2011, III onlyoccurred in 2012. 14 different PFGE types, including 4 new types(N, O,P and Q), were observed, in which B, D, F and G were the predominant types, holding 83.9%(141/168) of the total GBS strains. Ia corresponded to 11 PFGE types(A–H, N–P), in which type D predominated(51%). Ib represented 3 genotypes(I, J and Q) and III harbored only 2genotypes(N and F). Type N and Fsynchronously presented in Ia and III. In summary, the genetic diversity of tilapia GBS varied by serotypes and changed with geographical locations and years.Although Iastillpredominated, new rareserotypeIII alreadyoccurred in China. 相似文献
13.
14.
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
15.
Growth hormone (GH) and reproduction: a review 总被引：5，自引：0，他引：5
Florence Le Gac Odile Blaise Alex Fostier Pierre-Yves Le Bail Maurice Loir Brigitte Mourot Claudine Weil 《Fish physiology and biochemistry》1993,11(1-6):219-232
Interaction between growth and reproduction occurs in many vertebrates and is particularly obvious at certain stages of the life cycle in fish. Endocrine interactions between the gonadotropic axis and the somatotropic axis are described, the potential role of GH being emphasised. A comparative analysis of these phenomena in mammals, amphibians and fish, suggests a specific role of GH in the physiology of puberty, gametogenesis and fertility. It also shows the original contribution made by studies on the fish model in this field of investigations. 相似文献
16.
Two gonadotropins (GtH; Qa and Qb) were purified by gel filtration and ion exchange chromatography from the pituitaries of Indian walking catfish (Clarias batrachus). The presence of GtH during purification was assessed by in vitro oocyte maturation and in vivo steroidogenic activity, and their identities were determined by elution profiles, molecular weight, biological activities and yield. The molecular weights of Qa and Qb were 37 and 42 kDa, respectively, and composed of distinct subunits (Qa: 20 and 14 kDa and Qb: 26 and 18 kDa). Polyclonal antibodies raised against Qa immunostained Qa, Qb and pituitary GtH cells. A competitive Qa‐ELISA was developed whose sensitivity was 6.25 ng mL?1 (1.25 ng well?1) with intra‐ (3.5%) and inter‐ (12.4%) assay coefficients of variation. Displacement curves parallel to the standard were obtained with plasma and pituitary extracts of catfish, Qb and carp GtHII. The assay was validated by measuring the plasma Qa levels after LHRH treatment and in relation to ovarian growth in the female catfish during different reproductive phases. Based on the results, Qa and Qb corresponded to fish LH and FSH respectively. The findings will increase the knowledge of the mechanisms controlling fish reproduction and identification of sensitive phases in fish in captivity for hormonal manipulation. 相似文献
17.
Controlled infection of Poecilia reticulata Peters (guppy) with Tetrahymena by immersion and intraperitoneal injection 下载免费PDF全文
下载免费PDF全文 G Sharon M Pimenta‐Leibowitz M C L Vilchis N Isakov D Zilberg 《Journal of fish diseases》2015,38(1):67-74
Tetrahymena is a protozoan parasite, which infects guppy, Poecilia reticulata Peters, and causes substantial economical losses in commercial farms worldwide. Studies of guppy infected by Tetrahymena require standardized infection protocols. The LD50 for Tetrahymena infection of guppies by intraperitoneal (IP) injection was calibrated, and the level obtained was 946 parasites per fish. Guppy infection with Tetrahymena by immersion, imitating the natural route of infection via the integument, was studied under normal or stress conditions. Exposure to cold and netting (CNI) and to cold only (CI) followed by immersion exposure to 10 000 Tetrahymena per mL resulted in 22.5% and 19.2% mortality, respectively, as compared to 14.2% and 10% in groups that were netted only (NI) or non‐stressed (I). Histopathology revealed that immersion infection resulted in a systemic infection. Lysozyme levels, measured 3 weeks after infection, were significantly higher in the CNI group (288 μg per mg protein) compared with CI‐, NI‐ and I‐treated groups (94.5, 64 and 62.3 μg mg?1, respectively). There was no evident parasite immobilization activity in body homogenates, suggesting no development of acquired immunity. Re‐infection by IP injection revealed no increase in protection in any of the treatment groups, mortality range of 56.3–75%, higher than in the non‐exposed control (40.6% mortality). 相似文献
18.
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
19.
The endemic, anadromous cyprinidChalcalburnus tarichi is the only fish species known to occur in alkaline Lake Van (Eastern Anatolia, Turkey). EightC. tarichi were maintained individually in Lake Van water (17 – 19°C; pH 9.8; 153 mEq·I–1 total alkalinity; 22 total salinity) and tank water samples analyzed for 24 h in 2 to 4 h intervals. At zero time, < 1µM ammonia was present and urea was undetectable in the tank water; at 24 h, total ammonia and urea made up 114±32 and 35±25µM, respectively. Over the experimental period, ammonia-N and urea-N excretion averaged 1041±494 and 607±169moles·kg–1 fish·h–1, respectively. The extent of urea excretion was highly variable between specimens. Uric acid excretion was not detectable.Urea was present at high concentrations in all tissues and plasma (25 – 35moles·g–1·ml–1) of freshly caughtC. tarichi; total ammonia content of the tissues was by a factor of 1.9 (liver) to 3.0 (brain) lower. High arginase activity (2.4±0.2 U·min–1·g–1) was detected in the liver ofC. tarichi but ornithine carbamoylphosphate transferase, a key enzyme of the ornithine-urea-cycle, was absent. Ureagenesis is likely through degradation of arginine and/or uricolysis. High glutamine synthetase activity (11±0.6 U·min–1·g–1) and low ammonia content in brain suggest that, like other teleosts,C. tarichi has an efficient ammonia detoxification in the brain, but in no other tissue.Nitrogenous waste excretion at alkaline pH is discussed. The ability ofC. tarichi to excrete high levels of ammonia at extremely alkaline pH is unique among teleosts studied so far. The mechanism of ammonia excretion under Lake Van conditions remains to be elucidated. 相似文献
20.
There has been growing concern about the overuse of antibiotics in the ornamental fish industry and its possible effect on the increasing drug resistance in both commensal and pathogenic organisms in these fish. The aim of this study was to carry out an assessment of the diversity of bacteria, including pathogens, in ornamental fish species imported into North America and to assess their antibiotic resistance. Kidney samples were collected from 32 freshwater ornamental fish of various species, which arrived to an importing facility in Portland, Oregon from Colombia, Singapore and Florida. Sixty‐four unique bacterial colonies were isolated and identified by PCR using bacterial 16S primers and DNA sequencing. Multiple isolates were identified as bacteria with potential to cause disease in both fish and humans. The antibiotic resistance profile of each isolate was performed for nine different antibiotics. Among them, cefotaxime (16% resistance among isolates) was the antibiotic associated with more activity, while the least active was tetracycline (77% resistant). Knowing information about the diversity of bacteria in imported ornamental fish, as well as the resistance profiles for the bacteria will be useful in more effectively treating clinical infected fish, and also potential zoonoses in the future. 相似文献