Growth of Single Plant Cells

Suspension of plant cells from tissue cultures have been plated in nutrient agar medium so that practically all of the individual cells yielded colonies.     

Research Progress on the Large-scale Culture Technology of Mammalian Cells

The culture of mammalian cells is closely related to the development of biotechnology, which has been used extensively in the research and application fields of biology and medical science. In this article, various factors affecting cell cultivation and the application of microcarrier and bioreactor on large-scale culture of mammalian ceils were reviewed.     

CDK5在细胞中的调控机理

CDK5是一个多功能的丝氨酸或苏氨酸蛋白激酶,最主要的功能是调控发育的中枢神经系统的神经迁移。其与调节亚基P35,P39或P25的结合是保持活性及其调控功能最基本的策略。因此,CDK5的活性及功能调控主要受P35和P39在细胞内的表达水平、时空分布及稳定性等因素的影响。此外,CDK5的活性调控也与CDK5自身的表达水平、磷酸化作用以及CDK5/P35超大蛋白复合物中某些蛋白因子的影响密切相关。     

哺乳动物原始卵泡启动和生长的调控机理

从卵泡生长启动的早期指标、调控原始卵泡生长启动的因素等方面综述调控原始卵泡生长启动相关因子的最新进展。     

冷冻对哺乳动物胚胎发育分子调控的影响

综述了几种与哺乳动物胚胎发育分子调控相关的重要蛋白质以及超低温冷冻保存在分子水平上对胚胎发育的影响.     

哺乳动物胚胎干细胞分离与培养的研究进展

从胚胎干细胞的来源、分离方法和饲养层细胞等方面,总结了胚胎干细胞分离与培养在近年来所取得的进展。     

反向PCR鉴定piggyBac介导的哺乳动物细胞转基因研究

利用反向PCR技术,研究piggyBac介导的转基因哺乳动物中外源基因整合位点信息.首先在转座子piggyBac中插入巨细胞病毒(CMV)启动子元件驱动的绿色荧光蛋白基因(EGFP),构建用于转染哺乳动物细胞的转基因载体pXL - CMV - EGFP;同时构建以CMV启动子驱动的转座酶基因载体.将2种载体以脂质体共转...     

生长激素作用的分子机制

生长激素(Growth hormone简称GH)是垂体前叶合成和分泌的一种多肽激素,由垂体前叶合成和分泌的一种多肽激素.它是由垂体嗜酸性细胞产生的. 制备GH一般用牛、羊、猪等动物的垂体,通过硫酸铵沉淀,二乙氨乙基——纤维素层析纯化获得GH,一般得量较少.这种精制的GH均为一种不含糖的单链多肽,由190～191个氨基酸组成.有两个二硫键形成稳定的分子结构,分子量为2100～2200道尔顿.它的生物学功能是促进动物生长发育,促进蛋白质、核酸的合成,增加体重,增加毛量,抵制葡萄的氧化,动用脂肪组织释放出脂化的脂肪酸到血液中去,即脂肪的分解,增高血糖,促进碳水化合物的代谢,有调控代谢的作用.由于社会的发展,人们生活不断提高,对原先从动物垂体中提抽纯化GH已不能满足人们的需求,必须改变生产方式,动用现代基因工程技术,合成基因,扩大生产,满足人们日益增长的需要.     

本地肉犬不同饲养阶段能量和蛋白质需要的研究

本试验采用二因子交叉设计方法研究了不同能量、蛋白质水平日粮对本地生长肉犬采食量、生长速度和饲料转化率以及经济效益的影响，同时比较了不同生长阶段生产性能的差异，由此筛选不同生长阶段的最佳营养需要量。结果表明：全期平均日增重Ｂ１最高，与Ｂ４差异极显著（Ｐ＜０．０１），与Ｂ３差异显著（Ｐ＜０．０５），比Ｂ２差异不显著；饲料转化率亦以Ｂ１最高，比Ｂ２、Ｂ３、Ｂ４分别提高１４．２％、２３．１％和３９．２％；每千克增重饲料成本是Ｂ４＞Ｂ３＞Ｂ２＞Ｂ１。两因子测定结果最佳组合为Ａ１Ｂ１、Ａ１Ｂ２和Ａ３Ｂ１，其次为Ａ２Ｂ２、Ａ２Ｂ１和Ａ３Ｂ３。     

Energy Requirements for Maintenance and Growth of German Mutton Merino Crossbred Lambs

A comparative slaughter trial and a metabolism trial were conducted to determine the requirement of net energy (NE) and metabolizable energy (ME) by the crossbreed of German Mutton Merino×Inner Mongolia Merino for fattening from 35 to 50 kg of body weight (BW). 49 crossbred female lambs ((33.9±2.3) (SD) kg BW) of German Mutton Merino×Inner Mongolia Merino were used. 34 lambs were randomly chosen for comparative slaughter, which were offered an identical mixture diet (concentrate:roughage=55:45) at 100, 75 or 55% of ad libitum intake, whereas the remainders were used in the metabolism trial to evaluate the ME of the diet after methane production was measured by open-circuit respirometry. As feed intake decreased from 100 to 75 and 55% of ad libitum intake, the apparent digestibility of dry matter (DM) linearly increased (P=0.010) from 60.8 to 63.6 and 66.9%, respectively, and methane production decreased from 52.1 to 44.3 and 39.9 Ld-1, respectively, but the ratio of methane energy to gross energy intake increased linearly (P=0.010) from 8.20 to 8.96 and 10.97%, respectively. Consequently, the ME values of the diet increased from 9.35 to 9.64 and 9.85 MJ kg-1 DM, respectively. The NE requirement for maintenance (NEm) was 255 kJ kg-1 BW0.75, and the ME requirement for maintenance (MEm ) was 352 kJ kg-1 BW0.75, with a partial energy efficiency for maintenance (km) of 0.72. The NE requirement for growth (NEg ) ranged from 1.26 to 4.66 MJ d-1 as average daily gains increased from 100 to 300 g d-1, with a partial energy efficiency for growth (kg ) of 0.45. These results indicated that the NE g required by crossbred female lambs of German Mutton Merino×Inner Mongolia Merino was lower than the recommendation of the American or British nutritional system.     

Molecular Weight: Measurements with Gravity Cells

A gravity cell can be used to determine the weights of particles greater than 10(8) molecular weight units. The solution is maintained at a temperature which is constant to +/- 0.001 degrees C until equilibrium between sedimentation produced by gravity is balanced by back diffusion. The weight-average molecular (particle) weight of tipula iridescent virus was (1.05 +/- 0.02) x 10(9).     

植酸酶生产菌的筛选及生长条件的研究

从单胃动物的粪便垃圾堆中分离出一种可分泌植酸酶的青霉 .进一步的研究表明这种青霉培养液最佳的淀粉含量为 40g·L-1.青霉生长与其分泌植酸酶之间存在矛盾 .青霉生长旺盛时产酶少 ,测出的酶活性低 .青霉生长缓慢时产酶多 ,测出的酶活性高 .植酸酶大量分泌前伴随着培养液pH值的急剧下降     

硅肥在单季稻上的施用效应

在单季籼稻上施用硅肥可促进水稻生长发育 ,增强抗逆性 ,增加产量。硅肥以作基肥和追肥 2次施用较好 ,施用量为2 2 5～ 3 0 0kg/hm2 。     

对崔启武-Lawson种群增长模型的一些看法

本文通过对崔启武-Lawson模型理论基础的分析,认为该模型及建模过程均有缺陷,由模型本身及其理论基础不能得出在极端条件下崔-Lawson模型可转化为指数和Logistic方程的结论。     

单季晚稻强化栽培的生育特性表现及高产途径分析

试验结果表明 :单季晚稻实行强化栽培具有早栽早发 ,有效分蘖期长 ,单株分蘖多 ,根系发达等个体强化特征特性 ,其高产途径是强个体、适群体 ,争大穗 ,夺高产 ,是传统穗粒兼顾高产途径向大穗更高产途径改进的新型技术 ,不仅增产潜力大 ,而且省工节本。