Extractive fermentation of lactic acid by immobilizedLactobacillus casei using ion—exchange resin

Summary A novel method of lactic acid fermentation byLactobacillus casei immobilized in Ca—alginate gels is described, in which an ion—exchange resin packed column is attached to a fermentor for separation of lactic acid from fermentative broth. The technique successfully alleviated the restriction imposed by lactic acid on bacterial growth and product formation. As compared to the conventional batch fermentation, the new fermentation technique enhanced the lactic acid productivity and sugar conversion rate from 0.328g/L·h and 88. 2% to 0.482g/L·h and 98.6%, respectively.     

植物细胞离析酶的制备和应用

用 Aspergillus sp．A-19菌经固体发酵研制成一种新的植物细胞离析酶(SeparatasezA—P)。其离析单细胞的酶活力平均为70 767u／g,有效作用的pH在3．0—7．0,温度为20—45℃。发酵培养基配方是麸皮：桔皮粉：(NH₄)₂SO₄(w／w)为100:100:O．63,料水比为1 :2．0,培养适宜条件为25℃、60小时。     

鲤肠道正常菌群的研究

本实验用稀释滴种的定量方法,对淡水养殖地中健康鲤肠道内的１０种菌群进行了定性、定量分析,并对结果进行统计学处理,得到鲤肠菌群的一些生理值。结果表明鲤肠道中需氧、兼性厌氧优势菌是气单胞菌和酵母菌,厌氧优势菌是拟杆菌。对不同时间、不同温度条件下同一养殖池中鲤肠道菌群的测定结果比较表明：葡萄球菌、假单胞菌差异显著（ｐ＜０．０５）,气单胞菌、大肠杆菌、需氧芽胞杆菌、酵母菌、乳酸杆菌、双歧杆菌、拟杆菌、梭状芽胞杆菌差异不显著（ｐ＞０．０５）,表明该８种菌群在鲤肠道中的菌数处于相对稳定状态,属于肠道正常菌群。     

Differential adenoassociated virus vector-driven expression of a neuropeptide Y gene in primary rat brain astroglial cultures after transfection with sendai virosomes versus LipofectinTM

The ability of Sendai virosomes or Lipofectin^TM to introduce an AAV vector into primary rat brain astroglial cultures was characterized. The pJDT95npy vector was constructed by inserting rat NPY cDNA downstream from the indigenous AAV p5, p19 and p40 promoters in pJDT95. Lipofectin^TM-mediated transfection with pJDT95npy (10 g) resulted in pronounced expression of several NPY mRNA species: p5-driven (3.3 kb), p19-driven (2.7 kb) and p40-driven (0.6, 0.8, 1.1, and 1.8 kb). Exposure to virosomally encapsulated pJDT95npy (50 or 100 ng) resulted in transient expression of some p40-driven mRNA species (0.8 and 1.8 kb). Neither method produced astroglia cells which synthesized mature NPY immunoreactivity. This demonstrates that an AAV-derived vector can drive gene expression in astroglia, that Sendai virosomes can infuse vectors into astroglia, but that the amount of DNA infused in this manner may limit long term expression.     

斑须蝽三代卵块的空间分布和田间抽样技术研究

通过田间调查和计算,明确了斑须蝽三代卵块呈聚集分布,且以负二项分布为主。理论抽样数当t＝1．00,D＝0．3时,n＝13．091/＋63．878,如果防治指标定为百株虫卵块12块时,则最大抽样数为173株,序贯抽样的累积虫卵块数量界限为：T0（N）＝0.12N±0．4735。田间随机取样以平行线和Z字形为最佳。     

甜菜碱对呼吸酶的保护效应

以菠菜（Ｓｐｉｎａｃｉａ ｏｌｅｒａｃｅａ Ｌ．）叶片为材料,研究了不同浓度的甜菜碱和ＮａＣｌ对三羧酸循环、末端氧化和光呼吸的组成酶的活性的影响。与电解质ＮａＣｌ不同,高浓度的甜菜碱对这些酶的活性是非抑制性的,并对ＮａＣｌ的抑制作用有一定保护效应。甜菜碱是很好的有机渗透调节剂。这与甜菜碱在细胞质中起渗透调节作用,以及是无机渗透调节剂的配伍溶质的假设是一致的。     

Measles outbreak in 31 schools: risk factors for vaccine failure and evaluation of a selective revaccination strategy.

OBJECTIVE: To examine the risk factors for measles vaccine failure and to evaluate the effectiveness of a selective revaccination strategy during a measles outbreak. DESIGN: Matched case-control study. SETTING: Thirty-one schools in Mississauga, Ont. SUBJECTS: Eighty-seven previously vaccinated school-aged children with measles that met the Advisory Committee on Epidemiology''s clinical case definition for measles. Two previously vaccinated control subjects were randomly selected for each case subject from the same homeroom class. INTERVENTIONS: All susceptible contacts were vaccinated, and contacts who had been vaccinated before Jan. 1, 1980, were revaccinated. When two or more cases occurred in a school all children vaccinated before 1980 were revaccinated. MAIN OUTCOME MEASURES: Risk of measles associated with age at vaccination, time since vaccination, vaccination before 1980 and revaccination. RESULTS: Subjects vaccinated before 12 months of age were at greater risk of measles than those vaccinated later (adjusted odds ratio [OR] 7.7, 95% confidence interval [CI] 1.6 to 38.3; p = 0.01). Those vaccinated between 12 and 14 months of age were at no greater risk than those vaccinated at 15 months or over. Subjects vaccinated before 1980 were at greater risk than those vaccinated after 1980 (adjusted OR 14.5, 95% CI 1.5 to 135.6). Time since vaccination was not a risk factor. Revaccination was effective in reducing the risk of measles in both subjects vaccinated before 1980 and those vaccinated after 1980 (adjusted OR reduced to 0.6 [95% CI 0.1 to 5.3] and 0.3 [95% CI 0.13 to 2.6] respectively). However, only 18 cases were estimated to have been prevented by this strategy. CONCLUSIONS: Adherence to routine measles vaccination for all eligible children is important in ensuring appropriate coverage with a single dose. The selective revaccination strategy''s high labour intensiveness and low measles prevention rate during the outbreak bring into question the effectiveness of such a strategy.     

Homology models of two isozymes of manganese peroxidase: Prediction of a Mn(II) binding site

The three-dimensional structures of two isozymes of manganese peroxidase (MnP) have been predicted from homology modeling using lignin peroxidase as a template. Although highly homologous, MnP differs from LiP by the requirement of Mn(II) as an intermediate in its oxidation of substrates. The Mn(II) site is absent in LiP and unique to the MnP family of peroxidases. The model structures were used to identify the unique Mn(II) binding sites, to determine to what extent they were conserved in the two isozymes, and to provide insight into why this site is absent in LiP. For each isozyme of MnP, three candidate Mn(II) binding sites were identified. Energy optimizations of the three possible Mn(II) enzyme complexes allowed the selection of the most favorable Mn(II) binding site as one with the most anionic oxygen moieties best configured to act as ligands for the Mn(II). At the preferred site, the Mn(II) is coordinated to the carboxyl oxygens of Glu-35, Glu-39, and Asp-179, and a propionate group of the heme. The predicted Mn(II) binding site is conserved in both isozymes. Comparison between the residues at this site in MnP and the corresponding residues in LiP shows that two of the three anionic residues in MnP are replaced by neutral residues in LiP, explaining why LiP does not bind Mn(II). © 1994 Wiley-Liss, Inc.     

Zn对细胞保护作用机理的研究

应用扫描质子微探针和同步辐射ｘ荧光分析技术测定了细胞中元素的分布和组成,为确定Zn是细胞结构成分提供了直接的实验依据.用上述核技术结合有关生化指标,分析测定了正常和损伤细胞（脂质过氧化损伤）中Fe,Zn和丙二醛、SH基含量变化的相互关系.实验结果表明,当细胞发生脂质过氧化损伤时,Fe含量和丙二醛含量同步增高,而Zn含量和SH基量则降低.给细胞补充Zn后,提高了细胞质膜中的Zn含量,SH基量也随之增加,同时丙二醛量降低.提示Zn保护细胞完整性的作用机理之一是控制脂质过氧化作用.Zn可保护膜蛋白的SH基,减少和阻止被Fe所催化的过氧化反应.     

血管活性肠多肽结合核苷酸性质的研究

采用光亲和技术检测了血管活性肠多肽(VIP)与核苷酸之间的相互作用,发现VIP可以特异性结合同位素标记的GTP,还发现未标记的GTP以及其它三磷酸核苷抑制这种结合,这意味着VIP与上述三磷酸核苷之间的结合是一种典型的可逆性的结合反应.发现低浓度的GDP,GMP不但不抑制VIP与同位素标记GTP的结合反应,反而增强这种结合.联系到其它研究者关于GTP影响VIP与其受体结合反应的结果,可认为VIP能可逆性地连接一种三磷酸核苷,这种连接受反应系统中不同核苷酸比例影响,通过这种连接来调节VIP与其受体之间的反应.