海洋野生鱼酶解提取鱼油的工艺分析

海洋野生鱼与养殖鱼比较, 其鱼油中含更多的二十碳五烯酸（EPA）、二十二碳六烯酸（DHA）、脂溶性维生素等活性成分。为提高海洋野生鱼的利用价值, 以野生小带鱼为原料进行酶法提油工艺研究。分析了不同的温度, 时间, pH值等影响因素下的提取、萃取以及离心效果, 以响应面法确定了最佳的酶解工艺条件: 液固比为6、pH7.3、酶量1000 u/g原料、搅拌速度200 r/min、45oC酶解90 min; 最优萃取条件: 萃取剂100 mL(每20 g鱼糜原料)、pH4.0、40oC萃取25 min; 离心条件: 离心速度3000 r/min (1865 g)、离心时间10 min。上述工艺条件下提油率为79.90%。改进了传统的鱼油提取工艺, 在活性成分保护上有较大改善。     

离心机训练后+Gz耐力相关基因的分离与鉴定

为探讨离心机训练提高正向加速度 (forwardacceleration ,+Gz)耐力的分子机制 ,应用抑制性消减杂交 (suppressionsubtractivehybridization ,SSH)和斑点杂交技术筛选离心机训练 12d后测试高耐力组 (耐受 + 16Gz)与未训练对照组大鼠全脑的差异表达基因 .将获得的序列表达标签 (expressedsequencetag ,EST)进行特异性鉴定后 ,获得 7个上调EST ,其中 5个为已知基因的部分序列 ,2个为新EST ,它们的表达量均在训练 6d组最高 ,表明离心机训练可明显影响大鼠全脑特定基因的表达水平 ,这些基因表达水平的变化很可能与离心机训练提高机体 +Gz耐力的分子机制有关     

氯化钠密度梯度离心法制备用于显微注射的外源DNA片段

DNA显微注射是生产转基因动物最可靠和最常使用的一种方法,外源DNA的纯度对显微注射的成功起着至关重要的作用。本文介绍用氯化钠密度梯度离心的方法制备用于显微注射的外源DNA片段。与传统的琼脂糖凝胶回收的方法相比较,用此方法制备的外源DNA片段对小鼠受精卵进行显微注射后,受卵体母鼠的胚胎存活率,以及子代小鼠的外源基因整合率均有明显的提高。这一方法可为进一步提高转基因动物的成功率,提供方法学上的参考。 Abstract:DNA microinjection is the most popular and reliable method of producing transgenic animals.The purity of foreign DNA plays an important role for the success of microinjection.In this study,we introduced the use of sodium chloride step gradients in fractionating foreign DNA fragment for microinjection.The data demonstrated that,compared with the conventional agarose gel extraction method,NaCl purification scheme of toreign DNA could improve the treated embryo survival and foreign DNA intergration rate markedly.     

Effects of hypergravity on the elongation and morphology of protonemata of Adiantum capillus-veneris

Elongation growth of protonemata of Adiantum capillus-veneris , which can be controlled by light irradiation, was examined under acropetal and basipetal hypergravity conditions (from -13 to +20 g ) using a newly developed centrifugation equipment. Elongation of the protonemata under red light was inhibited by basipetal hypergravity at more than +15 g but was promoted by acropetal hypergravity from -5 to -8 g . Division of the protonemal cells that was induced by white light was inhibited under basipetal hypergravity at +20 g but was unaffected under acropetal hypergravity at -15 g . Upon exposure to continuous red light for 7 to 8 days, most of the protonemata grew as filamentous cells in the absence of a change in the normal gravitational force (control), but more than half of the protonemal cells were abnormal in terms of shape when maintained under hypergravity at +20 g .     

Ultra scaledown to predict filtering centrifugation of secreted antibody fragments from fungal broth

Extracellularly expressed anti-hen egg lysozyme single-chain antibody fragments (scFv) produced by Aspergillus awamori were recovered using filtering centrifugation. Two filtering centrifuges with 0.5- and 30-L capacities were used to represent laboratory- and pilot-scale equipment, respectively. Critical regime analysis using the computational fluid dynamics (CFD) technique provided information about the local energy dissipation rates in both units. Experimental data indicated loss of scFv activity for energy dissipation rates above about 2.0 x 10(4) W kg(-1). This loss of activity increased in the presence of gas-liquid interfaces during filtering centrifugation. An ultra scaledown filtering centrifuge with a maximum working volume of 35 mL was designed to mimic the operating conditions identified by the critical regime analysis for the laboratory- and pilot-plant-scale units. The recovered scFv activity levels and the separation performance of the three units were comparable when operated at equal maximum energy dissipation rates.     

Trypanoplasma salmositica: experimental infections in rainbow trout, Salmo gairdneri.

Trypanoplasma salmositica was successfully cultured in Hanks' medium with 10% heated fetal calf serum. The culture forms were morphologically similar to blood forms and were infective to rainbow trout by inoculation. T. salmositica produced a disease in experimentally infected rainbow trout (Salmo gairdneri). The clinical signs were anemia, exophthalmia, abdominal distension with ascites, and splenomegaly. These clinical signs were observed in fish that were infected with three substrains (field substrain, cultured substrain, and cloned substrain) thus satisfying Koch's postulates. The anemia was microcytic and hypochromic and was coincident with increasing parasite number in the blood. The hemoglobin in the infected fish dropped from a normal of about 6 g% to about 1 g% in the first 10 weeks postinfection. Similarly, the hematocrit and red cell count declined as the infection progressed. Abdominal distension and exophthalmia was obvious 10 weeks postinfection. Up to 5 ml ascites fluid were recovered from each of three fish. The fluid contained large numbers of Trypanoplasma and macrophages. Some of the macrophages were engulfing the Trypanoplasma. At about this time the spleen in the infected fish was enlarged 5 to 10 times over that of control fish. The hematocrit centrifuge technique was less sensitive than wet mount examinations for the detection of the organism in blood. Fluctuations in parasite number during the course of infection may be due to antigenic change by the parasite to evade the host immune system.     

Xylem vulnerability to cavitation can be accurately characterised in species with long vessels using a centrifuge method

Vulnerability to cavitation curves describe the decrease in xylem hydraulic conductivity as xylem pressure declines. Several techniques for constructing vulnerability curves use centrifugal force to induce negative xylem pressure in stem or root segments. Centrifuge vulnerability curves constructed for long‐vesselled species have been hypothesised to overestimate xylem vulnerability to cavitation due to increased vulnerability of vessels cut open at stem ends that extend to the middle or entirely through segments. We tested two key predictions of this hypothesis: (i) centrifugation induces greater embolism than dehydration in long‐vesselled species, and (ii) the proportion of open vessels changes centrifuge vulnerability curves. Centrifuge and dehydration vulnerability curves were compared for a long‐ and short‐vesselled species. The effect of open vessels was tested in four species by comparing centrifuge vulnerability curves for stems of two lengths. Centrifuge and dehydration vulnerability curves agreed well for the long‐ and short‐vesselled species. Centrifuge vulnerability curves constructed using two stem lengths were similar. Also, the distribution of embolism along the length of centrifuged stems matched the theoretical pressure profile induced by centrifugation. We conclude that vulnerability to cavitation can be accurately characterised with vulnerability curves constructed using a centrifuge technique, even in long‐vesselled species.     

动物离心机中大鼠行为状态无线视频采集装置的研制

目的：研制一种在正加速度作用下能实时观测大鼠行为状态的实验视频采集装置,为研究正加速度导致脑损伤的病理生理机制和防治措施提供新的方法。方法：依据正加速度对大鼠体位的要求和离心机特殊的环境,通过特制的大鼠座舱和无线视频采集单元来实现对动物离心机中正加速度作用下大鼠行为状态的实时观测;固定大鼠的座舱主要由胸部固定圈、身长调节圈、头部运动限制框构成;无线视频采集单元由2.4G无线摄像头、无线信号接收器、信号放大器、计算机以及视频采集软件组成。结果：座舱特殊的大鼠固定方式,既满足了正加速度对体位的要求,又不影响对大鼠行为状态的观测,2．4G无线视频采集技术保证视频信号在离心机高速旋转环境下的实时传输和观测,视频画面清晰流畅,并且能保存视频供回放分析。结论：动物离心机无线视频采集装置可用于正加速度作用下大鼠行为状态的实时观测与研究。     

Water relations of Robinia pseudoacacia L.: do vessels cavitate and refill diurnally or are R‐shaped curves invalid in Robinia?

Since 2005, an unresolved debate has questioned whether R‐shaped vulnerability curves (VCs) might be an artefact of the centrifuge method of measuring VCs. VCs with R‐shape show loss of stem conductivity from approximately zero tension, and if true, this suggests that some plants either refill embolized vessels every night or function well with a high percentage of vessels permanently embolized. The R‐shaped curves occur more in species with vessels greater than half the length of the segments spun in a centrifuge. Many have hypothesized that the embolism is seeded by agents (bubbles or particles) entering the stem end and travelling towards the axis of rotation in long vessels, causing premature cavitation. VCs were measured on Robinia pseudoacacia L. by three different techniques to yield three different VCs; R‐shaped: Cavitron P₅₀ = 0.30 MPa and S‐shaped: air injection P₅₀ = 1.48 MPa and bench top dehydration P₅₀ = 3.57 MPa. Stem conductivity measured in the Cavitron was unstable and is a function of vessel length when measured repeatedly with constant tension, and this observation is discussed in terms of stability of air bubbles drawn into cut‐open vessels during repeated Cavitron measurement of conductivity; hence, R‐shaped curves measured in a Cavitron are probably invalid.     

Use of focused acoustics for cell disruption to provide ultra scale-down insights of microbial homogenization and its bioprocess impact--recovery of antibody fragments from rec E. coli

An ultra scale-down (USD) device that provides insight of how industrial homogenization impacts bioprocess performance is desirable in the biopharmaceutical industry, especially at the early stage of process development where only a small quantity of material is available. In this work, we assess the effectiveness of focused acoustics as the basis of an USD cell disruption method to mimic and study high-pressure, step-wise homogenization of rec Escherichia coli cells for the recovery of an intracellular protein, antibody fragment (Fab'). The release of both Fab' and of overall protein follows first-order reaction kinetics with respect to time of exposure to focused acoustics. The rate constant is directly proportional to applied electrical power input per unit volume. For nearly total protein or Fab' release (>99%), the key physical properties of the disruptate produced by focused acoustics, such as cell debris particle size distribution and apparent viscosity show good agreement with those for homogenates produced by high-pressure homogenization operated to give the same fractional release. The only key difference is observed for partial disruption of cells where focused acoustics yields a disruptate of lower viscosity than homogenization, evidently due to a greater extent of polynucleic acids degradation. Verification of this USD approach to cell disruption by high-pressure homogenization is achieved using USD centrifugation to demonstrate the same sedimentation characteristics of disruptates prepared using both the scaled-down focused acoustic and the pilot-scale homogenization methods for the same fraction of protein release.