猪白介素4在CHO-K1细胞中的重组表达及生物学活性分析

将猪白介素4(Porcine interleukin4,PIL-4)基因亚克隆到真核表达载体pEGFP-N1中,构建重组表达质粒pEGFP-PIL-4,利用脂质体法转染CHO-K1细胞,采用荧光显微镜实时观察、RT-PCR和Western-blot分别检测CHO细胞转录表达目的分子的情况,通过MTT法检测所表达蛋白的生物学活性。结果在将重组质粒转染CHO-K1细胞中24、48 h后的均观察到绿色荧光;经G418筛选14~20 d后转染的细胞形成了阳性细胞集落,用RT-PCR扩增出约339 bp的目的基因片段;经Western-blot检测到约为39 000的特异蛋白分子条带,并证明在转染重组质粒的细胞中表达了高生物活性的重组蛋白。     

Effect of dietary carbohydrate to lipid ratio on performance of Nile tilapia and enhancement of natural food in pond aquaculture

This study tested the effect of two diets differing in carbohydrate to lipid (CHO:LIP) ratio (4.7 vs. 19.5 g/g) on the contribution of natural food and the total fish production in tilapia ponds. Eight ponds, each divided into three equally sized compartments, were assigned to one of the two diets, which differed in CHO:LIP ratio but had the same digestible protein to digestible energy (DP:DE) ratio (15.5 and 15.6 g/MJ). Ponds were fed equal amounts of crude protein. Three feeding levels (no, low and high) were nested in each pond in a split plot design. Average body weight of fish at stocking was 90 g, and the duration of the experiment was 42 days. Increasing the CHO:LIP ratio had no impact on tilapia production. However, the feeding level influenced both biomass gain, specific growth rate and survival. The apparent digestibility coefficient (ADC) for fat and carbohydrate was influenced by dietary CHO:LIP ratio but ADC for energy was unaffected. Proximate analysis of fish body composition showed no effect of diet except for levels of ash. Diet had no effect on the organic matter composition of the faeces, and the contribution of natural food to fish nitrogen gain. Therefore, we postulate that changing the dietary non‐protein energy source from lipid to carbohydrate does not have any impact on tilapia culture in semi‐intensive ponds.     

中国仓鼠卵巢细胞和人胚肾T细胞骨架及其迁移特性的比较

【目的】比较中国仓鼠卵巢(CHO)细胞和人胚肾T(HEK293T)细胞的迁移能力,筛选适用于细胞骨架形态和外源基因对细胞迁移影响研究的细胞系。【方法】通过免疫荧光组织化学比较CHO和HEK293T细胞骨架的形态差异,通过延时成像和划痕试验比较细胞迁移能力,通过免疫印迹比较2株细胞系细胞骨架基因的相对表达,并从细胞骨架差异和结构基因的选择性表达方面解释细胞迁移能力的差异。【结果】CHO和HEK293T细胞系的细胞骨架在形态上存在较大差异,HEK293T细胞系的核质比是CHO细胞的2.25倍;CHO细胞比HEK293T细胞的迁移能力强,是HEK293T细胞的2.9倍;2种细胞内α-Tubulin/β-Actin的比率存在较大差异,CHO是HEK293T的1.2倍。【结论】细胞中微管微丝的差异性分布及结构基因Tubulin和Actin的选择性表达是细胞迁移特性不同的关键因素。CHO细胞适用于涉及细胞骨架形态和外源基因对细胞迁移影响的研究,HEK293T细胞不适用于此类研究。     

Three-dimensional porous collagen/chitosan complex sponge for tissue engineering

A three-dimensional, porous collagen/chitosan complex sponge was prepared to closely simulate basic extracellular matrix (ECM) constitutes, collagen and glycosaminoglycan. The complex sponge was prepared by a lyophilization method and had the regular network with highly porous structure, suitable for cell adhesion and growth. The pores were well interconnected, and their distribution was fairly homogeneous. The complex sponge was crosslinked using 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) to increase its biological stability and enhance its mechanical properties. The crosslinking medium had a great effect on the inner structure of the sponge. The homogeneous, porous structure of the sponge was remarkably collapsed in an aqueous crosslinking medium. However, the morphology of the sponge remained almost intact in a water/ethanol mixture crosslinking milieu. Mechanical properties of the collagen/chitosan sponge were significantly enhanced by EDC-mediated crosslinking. The potential of the sponge as a scaffold for tissue engineering was investigated using a Chinese hamster ovary cell (CHO-K1) line.     

不同饵料蛋糖比对草鱼幼鱼生长性能、体组成和消化酶活性的影响

[目的]研究不同蛋糖比对草鱼幼鱼生长性能、体组成和肠道消化酶活性的影响,为草鱼营养需求研究及饵料配制提供参考依据.[方法]采用单因素设计,以饵料蛋糖比为影响因素,共配制6组等脂等能饵料,对应的蛋糖比值分别为2.00、1.50、1.14、0.88、0.67和0.50.草鱼幼鱼饲养于室内循环养殖系统中,日投饵3次,试验周期8周.[结果]蛋糖比对草鱼幼鱼存活率无显著影响(P>0.05,下同);末体重、增重率和特定生长率受饵料蛋糖比影响显著(P<0.05,下同),均随蛋糖比降低呈先升高后降低的变化趋势,在蛋糖比为0.88时达最高值;饵料系数同样受蛋糖比影响显著,且在蛋糖比为0.88时最低(1.72).随着饵料蛋糖比的降低,草鱼幼鱼蛋白效率比、氮保留率、脏体比、肝体比和腹脂率均显著升高,但对全鱼、胴体的蛋白和灰分含量无显著影响.全鱼水分含量随饵料蛋糖比的降低显著降低,而脂肪含量显著升高;胴体水分和脂肪含量及肝脏脂肪含量的变化趋势与全鱼一致.肠道蛋白酶和淀粉酶活性随着饵料蛋糖比降低呈先升高后降低的变化趋势,脂肪酶活性则显著升高.[结论]草鱼幼鱼饵料中添加适量糖可节约蛋白质,且适宜蛋白质和糖水平分别为30.61%和29.54%,最适蛋糖比为1.04;过高的饵料糖水平能显著增加草鱼幼鱼内脏器官的相对重量,促进体脂过度沉积和糖原合成.