人工养殖长鳍篮子鱼消化道指数及3 种消化酶活性分布

以体质量58.51 g±21.15 g、体长13.08 cm±1.856 cm的长鳍篮子鱼(Siganus canaliculatus)为实验材料,对其消化道指数和主要消化酶活性分布进行了研究.采用常规方法测定了长鳍篮子鱼的消化道指数,其比内脏重、比肝重、比胃重,比幽门盲囊重、比肠重、比肠长分别为0.1572±0.0230、0.0166±0.0060、0.0115±0.0070、0.004 3±0.002 1、0.020 2±0.0102、2.595±0.457;体质量与体长的回归方程为Y=0.080 6X2.5457(r=0.9777,P<0.01).蛋白酶在各消化器官中的比活力顺序为幽门盲囊>肠>肝脏>胃;淀粉酶的比活力顺序为肠>幽门盲囊>胃>肝脏;脂肪酶比活力顺序为幽门盲囊>肝脏>肠>胃;肠的总蛋白酶活、总淀粉酶活、总脂肪酶活在各消化器官中都最高.肝脏、胃、肠、幽门盲囊的A/P值分别为2.15、22.65、3.81,1.96.研究表明,肠道是长鳍篮子鱼消化食物的最重要的消化器官;根据消化道指数、消化酶分布、A/P值,表明长鳍篮子鱼是偏植食性为主的杂食性鱼类.     

海洋酵母菌胞外酶及其基因的最新研究进展

综述海洋酵母菌所产多种胞外酶的生产、纯酶性质及基因克隆工作的最新研究进展.从实验室建立的500多株海洋酵母菌种资源库中筛选出了数十株可以产生多种不同活性胞外酶的海洋酵母菌,它们分别属于耶鲁维亚酵母菌(Yarrowia)、类酵母(Aureobasidium)、毕赤氏酵母菌(Pichia)、梅奇酵母菌(Metschnikowia)和隐球酵母菌(Cryptococcus)等不同种属.所产生的胞外酶主要包括纤维素酶、碱性蛋白酶、酸性蛋白酶、淀粉酶(包括生淀粉酶)、菊糖酶、脂酶、植酸酶和嗜杀因子等.深入进行了各种胞外酶的生产,纯化及纯酶的性质研究,并对部分菌株的胞外酶基因进行了克隆、测序和表达,这些研究有助于对海洋酵母胞外酶的理论研究和生产应用价值的了解和对于海洋酵母菌资源、生理和遗传的进一步深入研究.     

真鲷脂蛋白脂肪酶基因顺式元件PPRE及在肝脏活体调控作用

从血液提取总DNA并构建基因组文库,克隆海水鱼真鲷(Pagrosomusmajor)脂蛋白脂肪酶(LPL)基因5′侧翼区序列,再通过竞争性聚合酶链式反应(PCR)方法,定量研究饲料中添加不同饱和度脂肪酸对其肝脏LPL基因mRNA表达水平的影响。结果表明,真鲷LPL基因5′侧翼区序列中存在顺式元件过氧化物酶体增殖物反应元件,其序列为TGAAGA TGACAT,与TATA(CATAA)盒序列相隔211bp;与喂饲料对照组比较,添加10%油酸可增加真鲷肝脏LPL基因表达水平,但差异并不显著(p>0.05)。用亚油酸或n 3高不饱和脂肪酸混合物取代添加油酸的一半(占饲料添加量的5%)后,导致真鲷肝脏LPL基因表达水平升高并出现显著性变化(p<0.05)。对真鲷肝脏LPL基因诱导表达随饲料中的脂肪酸不饱和度增加而增加,表明在活体条件下脂肪酸对真鲷肝脏LPL基因表达的诱导作用可能与脂肪酸的氧化代谢有关。n 3高不饱和脂肪酸通过过氧化物酶体增殖物激活受体诱导真鲷肝脏LPL基因表达,使真鲷食物脂质供应水平与其肝脏脂肪酸氧化代谢强度调控偶联起来,可能是真鲷对高脂食物(特别是富含n 3高不饱和脂肪酸食物)的一种适应。     

Identification of five strains of antarctic bacteria producing low-temperature lipase

1 IntroductionMicroorganism is an important constituentof the antarctic, arctic and deep sea ecosystemswhich are characterized as permanent lowtemperature. To adapt and survive in this ex-treme environment, these microorganisms pro-duce many distinctive substances such as poly-unsaturated fatty acids (PUFA), low-tempera-ture enzymes and novel pigments, etc. (Thomasand Dieckmann, 2002). Low-temperature en-zymes have a property of higher specific activ-ity (Kcat) at low temperature. Owing to…     

Optimization of conjugated linoleic acid triglycerides via enzymatic esterification in no-solvent system

We compared four esterifiable enzymes.The lipase Novozym 435 possessed the highest activity for the conjugated linoleic acid esterification during the synthesis of triglycerides.The triglycerides were synthesized by esterification of glycerol and conjugated linoleic acid(CLA) in a no-solvent system using lipase catalysis.We investigated the effects of temperature,enzyme concentration,water content,and time on esterification.Enzyme and water concentrations of up to 1% of the total reaction volume and a syste...     

Effects of different dietary lipid contents on growth and lipase activity of Eriocheir sinensis larvae

The effects of different dietary lipid content on the growth and lipase activity of Eriocheir sinensis larvae were studied in the paper. The results showed that the survival, metamorphic rate and weight gain of E. sinensis larvae at different stages of growth all varied significantly with lipid content (P<0.05). Further, the survival and metamorphosis rates were the highest during the larval phases Z₃ to Z₄, and the weight gain was the highest during the larval phases Z₅ to M. During the first 20 h after metamorphosis of every larval stage, the lipase activity increased over time at Z₁, Z₂, Z₃ and M and declined at Z₄ and Z₅, and was influenced significantly by lipid content (P<0.05). In addition, lipase activity at each larval stage began to respond to dietary lipid contents 4 h after the larvae were fed, and tended to be stable after 12 h. The diets with higher lipase activity and lower lipid content were selected to give the suitable recipe of lipid requirements at each larval stage. It was concluded that the suitable lipid requirements at Z₁, Z₂, Z₃, Z₄, Z₅ and M were 6%, 4%, 6%, 8%, 8% and 10%, respectively.     

Purification and Characterization of a Novel Lipase from Antarctic Krill

Lipase from Antarctic krill,with a molecular weight of 71.27kDa,was purified with ammonium sulfate precipitation and a series of chromatographic separations over ion exchange(DEAE)and gel filtration columns(Sephacryl S-100),resulting in 5.2%recovery with a 22.4-fold purification ratio.The optimal pH and temperature for enzyme activity were 8.0 and 45℃,respectively.Purified lipase had Km and Vmax values of 3.27mmolL−1 and 2.4Umg−1,respectively,using p-nitrophenyl laurate as the substrate.Lipase activity was enhanced by adding Ca2+and Mg2+ions in the concentration ranges of 0–0.5mmolL−1 and 0–0.3mmolL−1,respectively,while the activity was inhibited by a further increase in these ion concentrations.Fe3+and Cu2+ions showed obvious inhibitory effects on enzyme activity,and the inhibition rates were 71.8%and 53.3%when the ion concentrations were 0.5mmolL−1.     

真鲷(Pagrus major)脂蛋白脂肪酶基因表达与内脏脂肪蓄积营养调控定量研究

采用竞争性PCR方法 ,进行 4种营养状况对真鲷脂蛋白脂肪酶 (LPL)基因mRNA表达水平与内脏脂肪蓄积影响的定量研究。结果表明 ,真鲷LPL基因在肝脏存在营养诱导性表达 ,饥饿、高脂食物均是其表达诱导因子 ;在腹腔肠系膜脂肪组织存在组成性表达 ,其表达水平受摄食状态的影响 ,但饲料脂肪水平却不起作用。当真鲷喂食高脂食物时 ,诱导产生的大量肝脏LPL将为肝脏提供更多的来源于食物的游离脂肪酸 ,使肝脏有可能出现营养诱导性脂肪蓄积 ,但真鲷腹腔肠系膜脂肪组织LPL基因表达水平未出现适应性变化 ,其腹腔肠系膜脂肪组织将不可能作为营养诱导性蓄脂器官。由于上述营养状况对真鲷体重、腹脂指数、肝指数均没有产生显著性影响 ,说明真鲷具有在不同营养状况下与哺乳类相似的维持其内脏脂肪蓄积稳定的代谢机制 ,推测真鲷应存在某种在功能上与哺乳类相似的肥胖基因。     

4种金属离子对可口革囊星虫消化酶活力的影响

以酶学分析的方法研究4种金属离子(Cd2 、Cu2 、Pb2 、Zn2 )对可口革囊星虫纤维素酶、淀粉酶和脂肪酶活力的影响.4种重金属离子分别按《国家渔业水质标准》(GB11607-89)(Cd2 ≤0.005mg/dm3、Cu2 ≤0.01mg/dm3、Pb2 ≤0.05mg/dm3、Zn2 ≤0.10mg/dm3)的0、10、20、50和100倍设置实验梯度.实验表明,可口革囊星虫3种消化酶活力大小为纤维素酶＞淀粉酶＞脂肪酶;在实验设置的浓度范围内,Cd2 、Cu2 、Pb2 和Zn2 4种金属离子对可口革囊星虫的纤维素酶、淀粉酶和脂肪酶活力均产生显著影响.除脂肪酶外的其余2种酶各处理组的比活力均显著(P＜0.05)低于对照组.不同浓度金属离子对可口革囊星虫脂肪酶、淀粉酶和纤维素酶活力的影响表现出不同的变化趋势.