Presence of Different O Antigen Forms in Three Isolates of One Clone of Escherichia Coli

Escherichia coli strains ECOR2, ECOR3 and K-12 are very closely related in genotype as indicated by multilocus enzyme electrophoresis. We show that they have very different rfb regions indicating that recombination has occurred in this region, and we suggest that it may be associated with niche adaptation.     

Preliminary validation of an activation assay for ex vivo activated T cells utilized in cancer immunotherapy

An in vitro assay that measures the activation level of ex vivo activated (EVA) T cells currently being used in the adoptive immunotherapy of metastatic renal cell carcinoma has been developed. This assay is based on the ability of activated, but not resting. T cells to proliferate in response to the protein kinase C activator, phorbol myristate (PMA). To utilize this assay for in-process monitoring and control, we have begun an initial validation of the overall reproducibility of this assay. The proliferation of activated T cells in response to PMA, as measured by the mean cpm values of (3)H-thymidine incorporated, was demonstrated to have intra-assay coefficients of variation (cv's) for individual analysts that were typically less than 10% and rarely exceeded 20%. Activated T cells could be frozen and stored for at least 6 weeks with little or no deterioration in their ability to proliferate in response to PMA. Using these cells, inter-assay cv's that were typically less than 15% were obtained by individual analysts, and overall cv's of 10% to 25% were obtained for different samples assayed by different analysts at different times. This level of variability is very reasonable for a cellular assay. Furhter validation of this assay will address the issues of sensitivity, linearity and selectivity. To date, this assay has been used to analyze over 90 patient EVA cell samples and has revealed a broad range of proliferative responses to PMA. Taken together, these results suggest that this assay may be useful in defining the potency of the activated T cell used therapeutically.     

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.     

Detection of interchromosomal translocations within the Triticeae by RFLP analysis.

Twenty-three wheat/alien addition or substitution lines were screened using restriction fragment length polymorphisms for the presence or absence of 4/5 and 4/7 reciprocal translocations in the alien chromosomes. Such translocations have previously been identified in wheat and rye. Group 4 and group 5 Aegilops umbellulata, Triticum urartu, and Thinopyrum bessarabicum chromosomes were found to carry 4/5 translocations. Evidence for a 4/7 translocation was also found in Secale montanum. The presence of the 4/5 translocations in T. urartu indicates that the translocation predates the polyploidization of wheat. The implications of these results are discussed.     

Behavioral responses of the whitebacked planthopperSogatella furcifera (Homoptera: Delphacidae) on rice plants whose odors have been masked

In a two-choice test, moreS. furcifera females settled more often on exposed plants than on parafilm-masked ones, regardless of the susceptibility of rice varieties. This indicates that rice volatiles play an important role in the insect's short-range orientation to its host. The fact that more insects settled on exposed resistant Rathu Heenati (RHT) than to masked susceptible Taichung Native 1 (TN1) suggests that there must be certain common volatiles released by both varieties. Few females landed on masked plants of either RHT or TN1. This implies that the insect could not recognize at a distance that a plant was resistant or susceptible without olfactory stimuli.S. furcifera excreted less honeydew on masked plants than on exposed ones for both varieties and more on masked TN1 than on exposed RHT. The electronic monitoring of feeding behavior demonstrates that the insect made more frequent probes and had shorter phloem ingestion durations on exposed RHT than on exposed TN1 and on masked RHT than on masked TN1. Moreover, the insect had longer phloem ingestion durations on masked TN1 than on exposed RHT. These results suggest that volatile chemicals given off by resistant RHT plants have a negative effect on feeding.     

Mechanisms of TonB-catalyzed iron transport through the enteric bacterial cell envelope

The recent solution of enteric bacterial porin structure, and new insights into the mechanism by which outer membrane receptor proteins recognize and internalize specific ligands, advocates the re-evaluation of TonB-dependent transport physiology. In this minireview we discuss the potential structural features of siderophore receptors and TonB, and use this analysis to evaluate both existing and new models of energy and signal transduction from the inner membrane to the outer membrane of gram-negative bacteria.     

Expression of heat shock proteins during development of barley

Barley heat shock proteins have been cloned, characterized by hybrid release translation and sequenced. Clones coding for proteins of 17, 18, 30, 32 and 70 kDa have been obtained. Out of these the 32 and 30 kDa proteins have been characterized as precursors to plastidic proteins of 26 kDa by posttranslational transport and by cDNA sequencing. The coding regions of these two transcribed genes are highly homologous. Accumulation of the plastid HSP as well as of HSP 70 as well as their corresponding mRNAs has been studied in 2- to 6-day old seedlings and in the 7-day old barley leaf. The mRNA for all investigated proteins were only found after a heat shock; the mRNA levels increase towards the tip of the leaf and with development. Furthermore, under the conditions used the mRNAs for all investigated heat shock proteins accumulate in parallel. Unexpectedly, both proteins, HSP 70 and HSP 26, are found by western blotting in the 2-day old control plants in the absence of any inducing heat shock. At later stages of development and in the leaf gradient only immunoreactivity with HSP 70 was observed. In contrast to the levels of their mRNAs the highest levels of HSP 30–26 and 70 have been observed in the basal segments indicating that translational control plays a role during HSP expression. Under severe heat shock a protein of 30 kDa is induced whose identity is not known but which reacts with the antibody to HSP 30–26 and might represent the accumulating precursors of the plastidic proteins.     

尼群地平对实验性糖尿病大鼠心肌收缩性的影响

腹腔注射链脲佐霉素（６５ｍｇ／ｋｇ）诱发Ｗｉｓｔａｒ大鼠糖尿病。糖尿病发病４周后,向饲料中加尼群地平（３０ｍｇ·ｋｇ－１·ｄ－１）。结果表明,糖尿病４周时大鼠心室舒张功能首先受损,８周后心室舒张和收缩功能均明显受累。尼群地平处理对糖尿病大鼠的心肌收缩性有一定的改善作用。提示尼群地平对大鼠糖尿病性心肌病有一定有益作用。     

津白_3侏儒小鼠垂体前叶生长激素细胞的免疫细胞化学研究

津白_３侏儒小鼠（ｄＷ~ｔ）是１９８２年从津白_３纯系小鼠（ＴＡ_３）中发现,进而培育成侏的变种。本实验应用免疫细胞化学技术,对ｄｗ￣ｔ小鼠垂体前叶生长激素（ＧＨ）细胞进行观察,并根据体视学原理进行定量分析,以探讨ｄｗ~ｔ小鼠是否存在垂体发育缺陷。实验结果显示,ｄｗ~ｔ小鼠ＧＨ细胞的体积密度（Ｖｖ）和数密度（Ｎｖ）值均低于正常对照组,Ｐ＜０．０１～０．００１。表明ｄｗ~ｔ小鼠由于垂体前叶ＧＨ细胞数量减少,导致ＧＨ分泌不足,从而形成侏儒。     

缢蛏碱性磷酸酶胍溶液中分子折叠与活力变化研究

报道了缢蛏碱性磷酸酶（简称ＡＬＰ）经不同浓度盐酸胍处理时酶的分子构象所发生的变化以及酶变化和失活的动力学过程。在胍中酶荧光发射峰强度下降,紫外差光谱在２４６ｎｍ和２８５ｎｍ处出现２个负峰,ＣＤ谱中酶的α螺旋度下降,且随浓度增大,变化程度也加大。动力学研究表明,酶在０．５ｍｏｌ／Ｌ、１．０ｍｏｌ／Ｌ、２．０ｍｏｌ／Ｌ３．０ｍｏｌ／Ｌ、４．０ｍｏｌ／Ｌ盐酸胍中的变性速度常数分别为３．２１×１０~（－４）ｓ~（－１）、６．３８×１０~（－４）ｓ~（－１）、２．１７×１０~（－３）ｓ~（－１）、２．３３×１０~（－３）ｓ~９－１）、５．１７×１０~（－３）ｓ~（－１）;而酶在相应盐酸胍中的失活速度常数分别为２．３３×１０~（－４）ｓ~（－１）、３．５７×１０~（－４）ｓ~（－１）、５．８６×１０~（－４）ｓ~（－１）、１．１４×１０~（－３）ｓ~（－１）、３．４５×１０~（－３）ｓ~（－１）;表现为失活与构象伸展变化基本平行。