几种添加剂对宽体舌鳎盐溶蛋白凝胶特性的影响

鱼肉盐溶蛋白的凝胶特性与鱼糜制品的质地密切相关,而盐溶蛋白的凝胶特性又受到许多因素影响。为研究添加转谷氨酰胺酶(TGase)、海藻酸钠、卡拉胶、魔芋胶对宽体舌鳎盐溶蛋白凝胶特性的影响,本实验通过四元二次通用旋转试验设计,采用响应面法建立了宽体舌鳎盐溶蛋白凝胶保水性(Y)和凝胶强度(y)与各添加剂用量的二次多项回归方程,确定了TGase、海藻酸钠、卡拉胶、魔芋胶的适宜添加量分别为0.36%,1.00%,1.00%,0.71%,添加后舌宽体鳎盐溶蛋白凝胶网状结构致密均匀,保水性和凝胶强度分别为60.36%和55.20 g,比对照组分别增加了36.41%和351.80%。结果说明,合适的添加剂组合可以显著的增加宽体舌鳎盐溶蛋白凝胶的保水性和凝胶强度。     

Effect of fasting on physical/chemical properties of ordinary muscles in full-cycle cultured Pacific bluefin tuna Thunnus orientalis during chilled storage

Using the full-cycle cultured (FC) Pacific bluefin tuna [body weight 16.3±1.9 kg (pre-fasting group, pre-FG), 14.2±0.9 kg (post-fasting group, post-FG)], changes in the physical/chemical properties of the cephalal parts of dorsal (D) and ventral (V) ordinary muscles (OM) by fasting (6 days) during chilled storage (4°C) were investigated. Condition factors were 26.7 (pre-FG) and 20.3 (post-FG, P < 0.05). Fasting changed the liver color to green. Fasting also decreased the amount of protein and lipid contents of the DOM and VOM of FC tuna. The breaking strength and pH of the DOM and VOM of post-FG tuna were higher (P <0.05) than for pre-FG tuna during storage. In contrast, the glycogen contents of DOM and VOM of post-FG tuna were lower than for pre-FG tuna. The color values (L*, a* and b*) of DOM of post-FG tuna were lower than for pre-FG tuna throughout the storage period. In addition, the metmyoglobin (metMb) content of DOM of post-FG tuna was lower (P <0.05) than that of pre-FG tuna, and the metMb content of VOM of post-FG tuna remained low after fasting. These results indicate that fasting suppresses deterioration (especially meat color) of FC tuna muscles during chilled storage.     

3种改性方法对琼胶理化性质的影响

文章采用羧甲基化、过氧化氢氧化和羟丙基化3种方法对琼胶进行改性,通过比较表征改性前后琼胶的溶解性能、色泽、凝胶透明度、凝胶质构特性、IR分子结构和热稳定性,探究不同改性方法对琼胶理化性质的影响.结果显示,羧甲基化和羟丙基化后琼胶的溶解温度、凝胶温度、凝胶再溶温度和凝胶强度显著降低(P<0.05),琼胶凝胶软弹性和持水性...     

Influence of death struggle on the structural changes in chub mackerel muscle during chilled storage

ABSTRACT: Chub mackerel (34–35 cm, approximately 500 g), which were caught by fishing with a rod and line at the Bungo Channel, Oita prefecture, were rested overnight in a fish preserve and either killed by decapitation (control group) or allowed to struggle in air for 30 min (struggled group). Muscle samples were excised every 4 h, and measurements on breaking strength and histological observations were done for both groups. The breaking strength of muscle in the control group was significantly higher than that in the struggled group, whereby a decrease in breaking strength was delayed for 12 h compared to the struggled group. Light microscopy showed space extension among muscle cells in association with a decrease in breaking strength. Especially in the struggled group, the extended area was larger and the difference in area was significant at the time when breaking strength showed a significant difference. Using electron microscopy, the extended area showed cut and/or disappeared collagen fibrils. From these results, it was demonstrated that struggling to death promoted the degradation of collagen fibrils and the weakening of connective tissue and, resultantly, led to the faster softening of muscle of chub mackerel.     

虾夷扇贝横纹肌和平滑肌的蛋白分布及理化性质

为探讨虾夷扇贝闭壳肌中横纹肌(ST)和平滑肌(SM)蛋白分布特征及理化性质差异。对肌肉组织进行切片、苏木精—伊红染色后,在光学显微镜下观察肌肉组织形态,SDS-PAGE分析蛋白组成,通过盐溶性和Ca~(2+)-ATPase对理化性质进行了比较研究。研究表明,横纹闭壳肌的肌纤维更粗,肌细胞间更致密;Myorod蛋白仅存在于平滑闭壳肌中,在横纹闭壳肌中不存在;副肌球蛋白在平滑闭壳肌中含量为31%,横纹肌中仅为11%。2种肌肉盐溶曲线也完全不同,在0.05~1.0 mol/L盐浓度范围内平滑肌的溶解性呈S型曲线上升,而横纹肌呈直线型上升,这种差异可能与副肌球蛋白含量有关。此外,平滑肌和横纹肌肌原纤维蛋白Ca~(2+)-ATPase最适温度分别为35和30°C,活化能分别为23.4和11.3 k J/mo L。     

纤维绳索强度分析中线性回归与曲线拟合法的比较

介绍了对绳索的断裂强度与直径关系的直线回归、幂函数拟合及自然对数拟合的方法,图示比较了三种函数图形及其与标准指标值的偏差,分析了这三种方法所得结果的差别,其中自然对数函数的返回值与标准指标值最为接近。以自然对数函数对聚丙烯、聚乙烯和聚酰胺绳索产品国际标准建立了断裂强度与直径关系的数学模型。采用这种数据分析方法,在制定系列规格的产品标准中确定技术指标,比较具有规律性。     

Inhibition of post-mortem muscle softening following in situ perfusion of protease inhibitors in tilapia

ABSTRACT:     A method of introducing protease inhibitors into fish muscle through the bulbus arteriosus was developed using an in situ perfusion technique. Perfusion efficiency was initially tested using eosin and [³⁵S]-methionine. Visible fluorescence was observed in the gill, liver, intestine and dorsal muscle of the eosin-treated tilapia, and the occurrence of eosin in the blood vessels of the dorsal muscle was confirmed under a fluorescence stereoscopic microscope with ultraviolet light. The radioactivity of [³⁵S]-methionine was taken into the dorsal muscle and liver at a concentration of 7.8 Bq/g and 70.2 Bq/g, respectively, after perfusion with 1000 Bq/mL solution. Using the perfusion technique with four kinds of protease inhibitors dissolved in physiological saline, the type of proteases implicated in the post-mortem muscle softening in tilapia (867 ± 195 g, n  = 10/protease inhibitor) was investigated. After the perfusion of leupeptin (serine and cysteine protease inhibitor), benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (Z-VAD-fmk; caspase inhibitor), chymostatin (serine protease inhibitor) and ο -phenanthroline (metalloprotease inhibitor), the breaking strength of the perfused muscle was measured as a parameter of the meat toughness and compared with that of the control fish, which were perfused with physiological saline only. The reduction of breaking strength during storage was inhibited by the perfusion of leupeptin and Z-VAD-fmk.     

Prediction of cannibalism in juvenile black rockfish,Sebastes schlegelii (Hilgendorf, 1880), based on morphometric characteristics and paired trials

To predict the occurrence of cannibalism in the culture of larval black rockfish, Sebastes schlegelii, we developed a regression model based on morphometric measurements. First, 156 black rockfish were measured to obtain a theoretical model, that is L_{T prey} = 0.624 L_{T cannibal} + 0.835. Then, 202 trials of paired fish, together with 31 pairs of cannibalistic fish, were used to revise this model, and the practical model was constructed: L_{T prey} = 0.522 L_T cannibal + 4.908 (R² = 0.99). According to this equation, the threshold of size ratio was deduced, that is 1.30–1.69, which could be used to grade black rockfish by size and remove potential cannibals.     

Effects of immersion of larvae in oestradiol-17β on feminization, structural changes of gonad and growth performance in the Far Eastern catfish Silurus asotus (Linnaeus)

Immersion of 1‐day‐old Silurus asotus (Linnaeus) larvae in 50, 100 or 200 μg L^?1 oestradiol‐17β for 15 days altered gonad differentiation and gonadal morphology. The survival of the group immersed at the highest dose (200 μg L^?1) was reduced significantly (86%), whereas survival of the groups immersed at the lower doses was as high as that of untreated controls (94%). The sex ratio of the untreated group was close to 1:1 (female–male); however, the incidence of females was significantly higher in groups immersed in doses of 50, 100 and 200 μg L^?1, i.e. 86%, 92% and 99.4%, respectively. Ovarian morphology of feminized individuals was different to that of the controls; the ovary was morphologically rather similar to testis although it contained fully matured oocytes. Morphological changes in genital organs were also noted in fish exposed to oestradiol‐17β the shape and size of genital papilla were intermediate between those of normal male and female. During a 4‐month growth trial after the exposure, the feminized fish showed significantly improved growth performance over normal genetic males (P < 0.05), although the growth was not equal to that of normal genetic females (P < 0.05).     

Comparative study on thermal denaturation modes of myosin in walleye pollack and carp myofibrils as affected by salt concentration

ABSTRACT:   The effect of salt concentration on the thermal denaturation profile of myosin in walleye pollack and carp myofibrils was compared by studying the subfragment-1 (S-1) and rod denaturation rates upon heating. Species-specific denaturation mode observed at 0.1 M KCl was no longer detected when samples were heated above 0.5 M KCl, where S-1 and rod denaturation rates were identical to each other. As the heating of the chymotryptic digest of myofibril formed practically no rod aggregates, S-1 denaturation in a form of myosin was the rate limiting step for rod aggregate formation. As the aggregate formation by rod was remarkably suppressed by lowering the temperature, the free movement of myosin tail upon heating was suggested to play an important role in the rod aggregate formation in a high salt medium.     

Effect of enriched live feeds on survival and growth rates in larval Korean rockfish, Sebastes schlegeli Hilgendorf

High mortality frequently occurs in larval mass production of Korean rockfish, Sebastes schlegeli Hilgendorf. Nutritional deficiencies in live feeds, rotifers and Artemia nauplii, fed to larvae could be a reason. A series of experiments was carried out to evaluate the effect of nutritional enrichment of live feeds by ω‐yeast, Spirulina powder and Super Selco^TM on survival and growth rates in rockfish larvae. Preference of rockfish larvae for the live feeds was determined by analysis of stomach contents. In addition, the effect of green water produced by the use of Chlorella ellipsoidea and Spirulina powder on the growth performance of larvae was evaluated. Larvae fed rotifers nutritionally enriched with Super Selco showed significantly higher survival rates than those fed rotifers enriched with ω‐yeast. Larvae fed rotifers that were nutritionally enriched with both Super Selco and Spirulina together exhibited improved growth and survival rates. Larvae fed Artemia nauplii nutritionally enriched with Spirulina powder showed significantly higher survival than larvae fed Artemia nauplii without enrichment. When larvae were fed rotifers, Artemia nauplii or the mixture of rotifers and Artemia nauplii, the second and last group showed significantly higher survival than the first group. Fatty acid composition in live feeds was improved by enrichment of ω‐yeast and larvae fed this feed showed higher survival and growth rates compared with larvae fed non‐enriched feeds. No positive effect of green water in the tank produced with C. ellipsoidea or Spirulina powder was observed on survival and growth rates for larvae fed nutritionally enriched rotifers with Super Selco and Spirulina powder. However, when the larvae were fed Artemia nauplii that were nutritionally enriched with ω‐yeast and Spirulina powder, green water obtained by adding Spirulina powder to the tanks resulted in significantly higher growth rates of larvae than was obtained by adding C. ellipsoidea.     

磷对生长期草鱼肌肉理化参数、游离氨基酸、呈味核苷酸和游离脂肪酸组成的影响

为探索磷对生长期草鱼肌肉常规营养组成和理化特性,肌肉中游离氨基酸、呈味核苷酸和游离脂肪酸组成的影响,实验选择初始体质量为[(256.22±0.60) g]的健康草鱼540尾,随机分为6组,每组3个重复,分别饲喂含有效磷0.95 (基础饲料组,未添加)、2.46、3.96、5.68、7.10和8.75 g/kg的饲料60 d。结果显示,饲料中适宜水平有效磷显著提高了生长期草鱼肌肉蛋白质、水分、羟脯氨酸、∑氨基酸、∑鲜味氨基酸(UAAs)、∑甜味氨基酸(SAAs)、肌苷酸(IMP)、∑不饱和脂肪酸、∑多不饱和脂肪酸(PUFA)含量以及pH0 h和pH12 h,而肌肉剪切力、组织蛋白酶B和L活性、乳酸、饱和脂肪酸(SFA)含量显著降低。此外,当饲料中有效磷水平分别增加到3.96和5.68 g/kg时,生长期草鱼肌肉IMP和∑呈味氨基酸(UAAs+SAAs)的滋味活性值(TAV)分别达到最大值。适宜水平有效磷还显著提高了生长期草鱼肌肉PUFA/UFA及n-3 PUFAs/n-6 PUFAs比值。研究表明,适宜水平有效磷提高了生长期草鱼肌肉蛋白质含量、肌肉嫩度、系水力和pH值,增加肌肉呈味氨基酸...     

基于线粒体控制区的许氏平鲉养殖群体与野生群体比较研究

为研究许氏平鲉养殖群体与野生群体遗传结构及遗传多样性状况,采用PCR扩增获得许氏平鲉线粒体DNA控制区高变区片段,并对其进行比对分析。结果显示,在长度为451 bp的线粒体控制区片段中,养殖群体单倍型多样度(0.540±0.067~0.815±0.021)明显低于野生群体(0.883±0.053~0.944±0.028),而核苷酸多样度(0.001±0.001~0.007±0.004)与野生群体(0.004±0.003~0.007±0.004)相差不大,遗传多样性水平均较低。在52个单倍型中,养殖群体仅占12个,且有6个单倍型与野生群体共享。群体间遗传分化指数和AMOVA分析结果显示,养殖群体和野生群体之间以及养殖群体之间的遗传分化较大,而野生群体间遗传变异较小,组群间的遗传分化较小且不显著(ΦCT=-0.013;P0.05)。单倍型最小跨度树和NJ系统发育树均未检测到明显的谱系结构。     

Effects of microbial growth on the preservation of scallop muscle in a vital state

ABSTRACT:   Adductor muscles dissected from live scallop Patinopecten yessoensis were stored in oxygenated artificial sea water. The initial muscle adenosine triphosphate (ATP) level, approximately 7.5 µmol/g, remained longer at 5°C than at either 0 or 10°C. The pH of sea water decreased continuously and the consumption of dissolved oxygen increased even after muscle ATP was almost exhausted. The number of viable microbes, measured as colony-forming units (c.f.u.) in the muscle, increased to reach a plateau at approximately 10⁷−10⁸ c.f.u./g, while muscle ATP remained at high levels. After this time, muscle ATP sharply decreased. Antibiotics or sorbate added into the oxygenated sea water effectively inhibited both the growth of microbes and the decrease in the pH of sea water. Under these conditions, the retention period of muscle ATP was greatly extended. Thus, it seems most likely that scallop adductor muscle cells are suffocated by the limitation of oxygen supply caused by aerobic microbes grown on the surface of muscle tissue.     

耐盐红螺菌科细菌对淡水 池水质及细菌类群的影响

对耐盐红螺菌科光合细菌应用于淡水斑点叉尾Hui、彭泽卿养殖后，水化学环境因子、细菌类群及养殖生物的变化进行了研究。结果表明，鱼池泼施光合细菌后，水体NH4^+-N、NO2^--N、NO3^--N和COD下降，溶氧和pH上升；细菌类群及数量变化大致是：光合细菌提高3－50倍（多数在15－20倍）, 硝酸细菌提高3倍，硝酸细菌提高4－5倍；斑点叉尾Hui养殖池的主要异养细菌肠杆菌科细菌提高9．4％，气单胞菌属降低7．5％，彭泽鲫养殖池的主要异养细菌假单胞菌属降低16％，肠杆菌科提高21％；养殖生物的养殖效果是：斑点叉尾Hui鱼苗个体增重提高15．7％，彭泽卿苗个体增重提高12．8％。     

低渗溶液浓度对黄颡鱼精子活力和受精率的影响

为提高黄颡鱼(Pelteobagrus fulvidraco)人工授精的稳定性,分别用卵子和精子同步激活法以及预激活精子法,在6个梯度浓度(0%～0.5%)范围的低渗溶液中进行人工授精试验,比较精子活力、受精率和孵化率。结果显示:低渗溶液浓度与精子活力、精子激活率和受精率密切相关,在相同浓度的低渗溶液组中采用预激活精子法的受精率显著高于卵子和精子同步激活法(P<0.05),受精率相对应提高了7.7%～14.5%;低渗溶液的浓度和人工授精方式对孵化率无显著影响。结果表明在浓度0.3%的低渗溶液中采用预激活精子法的效果最好。     

Effect of partial harvesting strategies on Artemia biomass production in Vietnamese salt works

The effect of partial harvest strategies on the production of Artemia biomass was evaluated for 12 weeks under Vietnamese salt farm conditions. The initial stocking density was 100 nauplii L^?1. After 3 weeks of inoculation, Artemia adults were partially harvested at intervals of 1, 3, 6 and 9 days starting with an initial quantity of 30 kg ha^?1 day^?1 at first harvest, and then the quantity of harvestable biomass was adjusted according to the standing stock present in the culture pond, combined with the time needed to harvest these quantities and with the weight of biomass harvested in each pond. The results showed that in most cases, the total densities were not significantly different among harvesting frequencies (P>0.05). However, a relatively higher Artemia adult density and its standing stock were better maintained in the 3‐day than in the 1‐day interval, and were significantly higher compared with the other two harvesting frequencies. The total biomass yields were the highest (1587 kg ha^?1) in the 3‐day harvesting interval, followed by 1‐, 6‐ and 9‐day harvesting interludes, corresponding to 1323, 1091 and 975 kg ha^?1 respectively. However, no statistical difference was observed between the 1‐ and the 3‐day interval as well as between the 6‐ and the 9‐day harvest schemes (P>0.05). The results of this study suggest that partial harvest of Artemia biomass performed every 3 days appears to be an appropriate strategy to enhance biomass productivity.     

盐胁迫对雨生红球藻虾青素累积、虾青素合成相关酶基因表达和抗氧化指标的影响

为探讨盐胁迫对雨生红球藻(Haematococcus pluvialis)虾青素合成的影响与机理,以及雨生红球藻各抗氧化机制之间的关系,本研究采用生化和分子生物学方法研究了不同浓度(0.04 mol/L、0.08 mol/L、0.12 mol/L和0.16 mol/L)和不同时间(3 d、6 d和9 d)的盐(Na Cl)胁迫对雨生红球藻生长、虾青素积累、番茄红素β-环化酶(Lcy)、β-胡萝卜素羟化酶(Crt R-B)和β-胡萝卜素酮化酶(Bkt)基因表达、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和谷胱甘肽过氧化物酶(GSH-Px)的活性以及丙二醛(MDA)含量的影响。结果表明,各胁迫时间的雨生红球藻的密度均随着盐胁迫浓度的增加而不断下降,在盐胁迫的第9天,雨生红球藻的死亡率和孢子比例均随着盐胁迫浓度的增加而不断升高;雨生红球藻虾青素含量、Lcy、Crt R-B和Bkt基因表达量均随着盐胁迫浓度和时间的增加而不断提高;雨生红球藻SOD、CAT和GSH-Px活性以及MDA含量在不同浓度和不同时间的盐胁迫下与对照组(0.00 mol/L Na Cl)相比均升高,且在不同时间的0.12 mol/L Na Cl胁迫下与对照组相比均显著升高(P0.05);雨生红球藻虾青素含量、Lcy、Crt R-B和Bkt基因表达量在盐胁迫的早期(第3天)和中期(第6天)阶段较低,在盐胁迫的后期(第9天)阶段较高,而SOD、CAT和GSH-Px活性以及MDA含量在盐胁迫的早期和中期阶段较高,在盐胁迫的后期阶段较低。实验结果说明了适当浓度和时间的盐胁迫能促进雨生红球藻累积虾青素,雨生红球藻在盐胁迫下主要是通过提高虾青素合成相关酶基因的转录水平来促进虾青素的合成,其虾青素和抗氧化酶的抗氧化活性可能互为补充,共同保护雨生红球藻免受盐胁迫的氧化损伤。     

ATP含量与外源酶添加对罗非鱼肌原纤维蛋白磷酸化水平的影响

蛋白质磷酸化修饰可影响肌肉品质,为探究外源酶添加对罗非鱼肌原纤维蛋白蛋白质磷酸化水平的影响,向罗非鱼肌原纤维蛋白溶液分别加入蛋白激酶A（Protein Kinase A,PKA）、和碱性磷酸酶（Alkaline Phosphatase,AP）进行体外孵育,通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳和荧光染色测定不同时间段内的磷酸化水平变化。此外,通过将罗非鱼肌肉浸泡在不同浓度ATP 溶液中测定其肌原纤维蛋白蛋白磷酸化水平以探究ATP对其影响。结果显示,在0~72 h,PKA组磷酸化水平均显著高于对照组和AP组,PKA组整体磷酸化水平从0 h的0.35±0.01上升至12 h的0.37±0.01而后下降至72 h的0.29±0.01,总体呈先上升后下降的趋势,其中,肌球蛋白重链磷酸化水平和肌动蛋白磷酸化水平分别从0 h的0.73±0.01、0.86±0.01下降至72 h的0.58±0.02和0.68±0.01（P<0.05）。当孵育时间为0、4、24和48 h时,3组磷酸化水平均具有显著差异。在外源添加0.3 mol/L ATP后,结果显示肌原纤维蛋白整体磷酸化水平（0.46±0.001）显著高于对照组（0.42±0.01）。PKA可促进罗非鱼肌原纤维蛋白磷酸化修饰,而碱性磷酸酶则使其去磷酸化。研究表明,宰后罗非鱼肌肉中的ATP含量、PKA及AP活性水平是影响蛋白质磷酸化水平的关键因素。本研究可为探明罗非鱼品质变化机制与调控策略提供理论依据。