Production of 2,3-butanediol in a membrane bioreactor with cell recycle

Summary The production of 2,3-butanediol by Enterobacter aerogenes DSM 30053 was studied in a cell recycle system with a microfiltration module. Emphasis was put on the influence of oxygen supply, cell residence time, dilution rate, and pH. Under optimal conditions a productivity as high as 14.6 g butanediol + acetoin/l per hour was achieved with a product concentration of 54 g/l and a product yield of 88%. This productivity is three times higher than that of an ordinary continuous culture. The achievable final product concentration of a cell recycle system was limited by the accumulation of the inhibiting by-product acetic acid, which increased very rapidly at low dilution rate. To maximize product concentration a fed-batch fermentation was carried out with stepwise pH adaption at high cell density. A final product concentration of 110 g/l was obtained with a productivity of 5.4 g/l per hour and a yield of 97%.     

Further investigation on nuclear transplantation in different orders of teleost: the combination of the nucleus of Tilapia (Oreochromis nilotica) and the cytoplasm of Loach (Paramisgurnus dabryanus).

The nucleus of a blastula cell from Tilapia (Oreochromis nilotica, family Cichlidae, order Perciformes) was transplanted into an enucleated egg of Loach (Paramisgurnus dabryanus, family Cobitidae, order Cypriniformes). From among 3747 nucleo-cytoplasmic hybrid (NCH) eggs two NCH larval fish (0.05%) were obtained; one died on the 6th day and the other died on the 12th day after the operation. Morphological examinations showed that both NCH larval fish had developed normally with an opened mouth except they could not take food after complete utilization of their egg yolk on the 5th day of development. The possible mechanisms for obtaining such inter-order NCH larval fish are discussed. This is the first report indicating that inter-order NCH larval fish can be obtained in spite of their evolutionary divergence.     

A method for studies of an El Tor-associated antigen of Vibrio cholerae O1

A method for studying the biotype El Tor associated mannose-sensitive haemagglutinin (MSHA) of V. cholerae O1 has been developed. By using crude MSHA adsorbed to chicken erythrocytes as solid phase antigen in an enzyme-linked immunosorbent assay (ELISA), antisera against V. cholerae of the El Tor biotype reacted in high titre with the MSHA-coated cells, whereas antisera against vibrios of the classical biotype did not bind significantly, i.e. in higher titre than pre-immune sera. The binding of anti-MSHA serum, or a monoclonal antibody against MSHA, to the MSHA-coated erythrocytes could be efficiently inhibited by crude MSHA as well as by El Tor vibrios whereas neither V. cholerae lipopolysaccharide nor different strains of classical vibrios had any inhibitory effect. These results support the existence of an El Tor-associated immunogen. They also suggest a possibility of determining antibodies against different haemagglutinins in ELISA without having access to purified antigens.     

Increased 5-Hydroxytryptamine and Norepinephrine Release from Rat Brain Slices by the Red Sea Flatfish

The effect of the Red Sea flatfish toxin pardaxin was examined on K+-evoked and on basal release of either [3H]norepinephrine or [3H]5-hydroxytryptamine from preloaded rat cortical slices. The K+-induced release of the neurotransmitters was stimulated in a dose-related manner at concentrations ranging from 0.5 to 4 micrograms/ml. Basal release of the two transmitters was elevated to a lesser extent. Although the stimulation of evoked release was approximately equivalent for the two neurotransmitters, the response to 5-hydroxytryptamine was reversible whereas that of norepinephrine was not washed by 20 min of superfusion. The mechanisms involved in producing these actions of pardaxin are not known; however, they may be mediated by changes in electrolyte fluxes across the neuronal membranes.     

血友病患者血清中淋巴腺病病毒/人T细胞Ⅲ型病毒抗体检测

对浙江省1982～1984年注射了美国产浓缩Ⅶ因子制剂的18例血友病患者,用酶联免疫吸附法(ELTSA)检测了血清中淋巴腺病病毒/人T细胞Ⅲ型病毒(LAV/HTLV-Ⅲ)抗体,发现4例阳性,并经免疫荧光试验和Western印迹法证实。2例应用了国产浓缩Ⅷ因子者抗体阴性。一例从美国来华旅游死于艾滋病者,LAV/HTLV-Ⅲ抗体阳性。本研究证明,LAV/HTLVⅢ病毒巳通过美国生产的Ⅷ因子制剂传入中国。     

百日咳杆菌去内毒素及保护性抗原的纯化

内毒素(Endotoxin,简称ET)是百日咳全菌苗(Bordetellapertussis vaccine)产生副作用的主要毒素之一,且不易除去。现有的分离方法,如蔗糖密度梯度离心法,较繁琐,成本高。本文采用Sepha-cryl S-300凝胶层折法可以简便有效的去除大部分内毒素。初步毒素试验结果表明:已达到日本生物制品规格的要求。两种保护性抗原FHA和LPF-HA也得到进一步分离纯化,为今后研制高效的百日咳组分菌苗提供了实验条件。     

伸展素在黄瓜胞壁中的转化及其与羟脯氨酸和异联酪氨酸的关系

用~(14)C-Pro和~3H_2-Tyr离体暗培养黄瓜子叶,发现细胞质、SECW和RCW中的Hyp/Pro和Idt/Tyr都随时间呈线性增加。这两种比值后两者高于前者,而两种比值增加速度之比在胞质部分最大、RCW中最小。表明在胞质和胞壁中都有Pro羟化和Tyr异联化过程,但羟化作用主要发生在胞质中,异联化主要在RCW中。 理化处理(高渗溶液和CHM)和放射性示踪证明胞质中存在HRGP库;它被分泌到胞壁后,先以离子键与壁结合,后转变为共价键与壁结合的伸展素。     

Dual action of respiratory inhibitors: inhibition of germination and prevention of dormancy induction in lettuce seeds

`Grand Rapids' lettuce Lactuca sativa L. seeds germinate readily at 15°C but poorly at 25°C in darkness. When held in dark at 25°C for an extended period, the ungerminated seeds become dormant as shown by their inability to germinate or transfer to 15°C in darkness. Induction of dormancy at 25°C was prevented by exposure to CN<sup>−</sup>, azide, salicylhydroxamic acid (SHAM), dinitrophenol, and pure N<sub>2</sub> as determined by subsequent germination at 15°C on removal of inhibitors. The effectiveness of inhibitors to break dormancy declined as dormancy intensified. At relatively low levels, CN<sup>−</sup>, SHAM, and azide promoted dark germination at 25°C while at high levels they were inhibitory. Uptake of O<sub>2</sub> by seeds held at 25°C for 4 days in 1.0 millimolar KCN was inhibited by 67% but was promoted 61% when KCN was removed. Correspondingly greater inhibition (79%) and promotion (148%) occurred when 1.0 millimolar SHAM was added to KCN solution. When applied alone, SHAM had little effect on O<sub>2</sub> uptake. These data indicate that Cyt pathway of respiration plays a dominant role in the control of both dormancy induction and germination of lettuce seeds, and `alternative pathway' is effectively engaged in presence of CN⁻. The channeling of respiratory energy use for processes governing germination or dormancy is subject to control by physical and chemical factors.

A scheme is proposed that illustrates compensatory use of energy for processes controlling dormancy induction and germination. A block of germination, e.g. by low water potential polyethylene glycol solution or a supraoptimal temperature spares energy to be utilized for dormancy induction while a block of dormancy induction by low levels of CN⁻ (similar to GA and light effects) drives germination. Blocking both processes by inhibitors (e.g. CN⁻, CN⁻ + SHAM) presumably leads to accumulation of `reducing power' with consequent improvement in O₂ uptake and oxidation rates of processes controlling germination or dormancy induction upon removal of the inhibitors.

     

Sister chromatid differential staining and NOR activity of BrdU-resistant sublines

Summary Two 30 g/ml BrdU-resistant sublines and two 60 g/ml BrdU-resistant sublines are induced from a Chinese hamster cell line Wg3h (HGPRT^–) by one-step and two-step selections, respectively. By inoculating the cells into BrdU-free medium or by adding more BrdU into the culture medium for 26–27 h, it was found that the two BrdU-resistant sublines analysed have very clear sister chromatid differential (SCD) staining patterns. This indicates that some of the nuclear DNA of the BrdU-resistant cells incorporate with BrdU to reach a kinetic balance. Frequencies of sister chromatid exchange (SCE) of the resistant cells are twice to four times as high as those of the Wg3h cells, depending on which BrdU-resistant subline is analysed. The SCE frequencies of the resistant cells also increase with the BrdU concentration in the medium. Analysis of silver-stained nucleolar organizer regions (NORs) indicates that the NOR activity of three out of the four BrdU-resistant sublines is significantly suppressed, i.e., averages of the Ag-NOR number and number of the chromosomes bearing Ag-NORs per cell decrease significantly. The degree of suppression for different BrdU-resistant sublines may be quite different. The suppressed NOR activity of the resistant cells can gradually be restored when the cells are inoculated into BrdU-free medium, but the recovery speed is far lower than that of the Wg3h cells. The suppression of the NOR activity of the BrdU-resistant sublines should be due to BrdU toxicity.