几种生理因子对印楝细胞悬浮培养生长的影响

通过研究不同生理因子对印楝悬浮细胞生长的影响 ,建立了一种快速生长的印楝细胞悬浮培养体系。结果表明 ,在添加了 6 BA 0 .8mg/L、NAA 0 .8mg/L、蔗糖 3 0 g/L且初始 pH值为 5 .8的MS培养液中 ,以 60g/L的接种量进行印楝细胞的悬浮培养 ,细胞生长速率可达 4.49g/L·d。     

Transgenic tobacco cell cultures expressing a Trichoderma harzianum endochitinase gene release the enzyme into the medium

 Calli and cell suspensions were obtained from tobacco plants transformed with an endochitinase-encoding cDNA from the biocontrol fungus Trichoderma harzianum. Calli from four primary transformants had high levels of endochitinase activity, like the plants from which they were derived. Endochitinase activity was also detected in the medium surrounding the calli and in the medium from transgenic cell suspensions. Western blots demonstrated the presence of the expected 40-kDa T. harzianum protein in transgenic samples but not in controls. These results indicate that the fungal enzyme is secreted and that the fungal signal peptide in the cDNA construct functions in plant cells. A cell suspension medium in which the protein concentration was increased up to 34-fold by ammonium sulfate precipitation inhibited germination of Penicillium digitatum spores. Some inhibition of spore germination was also observed in concentrated medium from control suspensions, probably due to the secretion and concentration of endogenous enzymes. Received: 6 May 2000 / Revision received: 6 September 2000 · Accepted: 14 September 2000     

Development and improvement of a serum-free suspension process for the production of recombinant adenoviral vectors using HEK293 cells

Human Embryonic Kidney 293 (HEK293) cells were adapted into a serum-free suspension medium through steps of gradual serum weaning for the production of adenoviral (AdV) gene therapy vectors. The presence of sodium heparin in the medium formulation reduced cell clumping dramatically in suspension culture. The adapted cells were ready to grow either in serum-containing medium as an attached culture or in serum-free medium in suspension culture. A scalable production process was developed in shake flasks and was then evaluated in stirred tank bioreactors. This process includes a growth phase in batch-mode followed by a production phase involving medium perfusion and supplementation. Fortification with calcium chloride post viral inoculation resulted in an increase in virus production by at least one fold. Addition of stimulating agents such as sodium butyrate, N-acetyl-L-cysteine (NAC), dimethyl sulfoxide(DMSO), or ethyl alcohol post infection was shown to further improve virus production in a dose-dependent manner. The serum-free suspension process described here should be suitable for the manufacturing of other E1-deleted AdV vectors and could potentially be used for the production of recombinant proteins by HEK293 cells. This revised version was published online in August 2006 with corrections to the Cover Date.     

A highly thermostable,alkaline CMCase produced by a newly isolated Bacillus sp. VG1

An extracellular, highly thermostable and alkaline CMCase was purified from Bacillus sp. VG1 using ion exchange and gel filtration chromatography. Enzyme was optimally produced in a medium containing 1.0% CMC and 0.5% tryptone. The purified CMCase had a pH optimum of 9–10 and a half life of 12 min even at 100 °C. The enzyme activity was reduced by Hg²⁺ and stimulated by Co²⁺, Na⁺ and K⁺. Various detergents and proteinases moderately inhibited the CMCase activity. The molecular weight studies showed a single band on SDS–PAGE.     

真菌诱导子对悬浮培养南方红豆杉细胞态势及紫杉醇合成的影响

在南方红豆杉细胞悬浮培养过程中,研究了在指数生长期的末期加入真菌诱导子(尖孢镰刀菌的胞壁组分粗提物)对细胞态势及紫杉醇合成的影响。结果表明,真菌诱导子能在短期内激发细胞的防御性应答反应而产生氧迸发,细胞的氧化还原态势发生了明显的变化,培养基发生碱化现象,表征酶含量的蛋白质含量明显提高,SOD、POD、CAT的活力出现波动性变化,并具有一定的时序性。同时,南方红豆杉悬浮培养体系中产次生代谢途径中重要的酶PAL的活力得到提高,紫杉醇的合成被加强,产量得到了显著提高,达到了对照组的5倍左右。     

醋酸纤维素固定化酰化酶膜的研究

采用正交实验法,考察了铸膜液配比对醋酸纤维素固定化氨基酰化酶微孔滤膜的影响,对酶膜的泡点压力、孔径、孔隙率及透水速率等性能进行了表征.结果表明,铸膜液组合最佳时,酶相对活力产率高达98.2%,酶膜的透水率适当,重复使用10次后仍保留原活力的79.7%,而其存放稳定性也大大提高.     

Eichhornia crassipes-based tertiary treatment of Kraft pulp mill effluents in Chilean Central Region

This paper presents experimental results on the implementation of Eichhornia crassipes–based tertiary lagoon to treat effluents generated by a 300 ton d^–1 Kraft pulp mill in Chile. Results show that E. crassipes rapidly adapted to the tertiary lagoon conditions. Active growth was maintained even during a cold winter, protected by the wastewater heat content. A 1000 m² seeding area extended to 2300–6200 m² after a month of growth, with a monthly harvested biomass and nitrogen uptake were 1.1–5.4 ton (dry wt.), and 18–127 kg N, respectively. E. crassipes growth was adequately described by a first order model, with an estimated rate constant ca. 0.03 d^–1 and 0.06 d^–1, for winter and summer seasons, respectively. A management strategy based on such model, to account for seasonal variations in growth rate while keeping a constant nitrogen uptake capacity, is proposed here.     

Cytoplasmic acidification with butyric acid does not alter the ionic conductivity of plasmodesmata

Summary The effect of lowering cytoplasmic pH on the ionic conductivity of higher-plant plasmodesmata was investigated with corn (Zea mays L. cv. Black Mexican Sweet) suspension culture cells. Exposure to butyric acid decreased the cytoplasmic pH by 0.8 units. Intercellular communication was monitored by electrophysiological techniques that allowed the measurement of membrane resistances of sister cells and the electrical resistance of the plasmodesmata connecting them. The decrease in cytoplasmic pH did not affect the resistance of plasmodesmata, despite the fact that the butyric acid treatment more than doubled the concentration of cytoplasmic calcium. This is discussed in light of previous findings that increases in cytoplasmic calcium increase the electrical resistance of plasmodesmata.Dedicated to Professor Brian E. S. Gunning on the occasion of his 65th birthday     

南方红豆杉细胞悬浮培养条件优化研究

针对红豆杉细胞生长相对缓慢和培养褐化问题,本文通过正交实验和均匀实验方法并采用人工神经网络技术对南方红豆杉细胞悬浮培养条件进行优化,使细胞的生长速率和比生长速率有较大提高,并考察了细胞活性随时间的动态变化.     

纤维素制酒精的分散、耦合、并行系统

生物转化是纤维素制酒精的有效途径。以强化纤维素酒精生物转化过程,降低转化成本为目的,在对该过程深入分析的基础上,提出了纤维素制酒精的分散、耦合、并行系统并阐述了其设计原则与解决方案,有普遍意义。