盐或低温胁迫对花生幼苗下胚轴ATP酶和质膜中PIP2含量的影响

经６％－１２％Ｄｅｘｔｒａｎ Ｔ７０密度梯度离心,获得了纯度较高的７ｄ龄花生幼苗下胚轴质膜和液泡膜制剂。１５０ｍｍｏｌ／Ｌ ＮａＣｌ或１０℃低温处理花生幼苗２４ｈ,其下胚轴质膜上的Ｍｇ＾２＋激活的ＡＴＰａｓｅ活性分别提高了３７．６％和１７．２％;Ｃａ＾２＋－ＡＴＰａｓｅ活性分别提高４５．８％和３３．６％。上述盐或低温处理也提高了液泡膜上Ｍｇ＾２＋激活的ＡＴＰａｓｅ活性,分别为对照的１４１．２％和１     

On line estimation of oxygen uptake rate for insect cells growing in a modified spinner flask

The simple design of traditional spinner flasks makes the on-line estimation of cellular metabolism impossible. An on-line estimation system has been developed and used for the monitoring of oxygen uptake rate (OUR) for insect cells growing in a modified spinner flask. Neglect of oxygen desorption from culture media is a common source of error in OUR measurements for Sf21 cells. Therefore, an algorithm was developed to compensate for the affect of such desorption process on the determination of OUR. A modified spinner flask was successfully used as a low-volume bioreactor for insect cell cultivation and the OUR measurement developed here is both convenient and reliable.     

Structural basis for the RNA binding selectivity of oligonucleotide analogues containing alkylsulfide internucleoside linkages and 2'-substituted 3'-deoxyribonucleosides.

In this report we describe the synthesis of oligonucleotides containing sulfide-linked dinucleoside units, namely rT(2'OH)sdT, rT(2'OMe)sdT, dTsrU(2'OMe) and dT(2'OMe)srU(2'OMe). We also describe the interactions of such oligomers with complementary DNA and RNA targets, and provide the structural basis for their remarkable RNA binding selectivity. In all cases, the Tm values of the S/P-chimera duplexes were lower than those of the corresponding unmodified duplexes. We attribute this to steric interactions between the 5'sulfur and the atoms of the nearby base/sugar residues. The 2'-substituents (i.e., 2'OH or 2'OMe) vicinal to the alkylsulfide internucleoside linkage significantly perturb the structure and stability of the duplexes formed with DNA, and more so than with RNA. The introduction of three rT(2'OH)sdTp (or rT(2'OMe)sdTp) units into an oligodeoxynucleotide sequence was sufficient to abolish binding to complementary DNA but not RNA. The same three substitutions with dTsrU(2'OMe)p and dT(2'OMe)srU(2'OMe)p did not abolish binding to DNA but the resulting complexes had poor thermal stability. The RNA-binding 'selectivity' exhibited by these oligomers is attributed to the tendency of the 2'-substituted (branched) furanoses to adopt the C3'-endo pucker, a conformation that is inconsistent with the B-form structure of helical DNA. The preference of these sugars to exist often exclusively in the C3'-endo form is attributed to stereoelectronic effects, namely gauche and anomeric effects. Our findings support the hypothesis that nucleoside analogues puckered exclusively in the C3'-endo form may result in them being especially good binders of targeted mRNA [S.H. Kawai (1991), Ph.D. Thesis, McGill University; Kawasaki et al. (1993) J. Med. Chem. 36, 831-841].     

五步蛇主要数量性状与排毒量的相关分析

本文首次报道了五步蛇身体主要部位的数量性状与其排毒量的关系。其中我们发现与排毒量有关的部位是头积、体粗、体重、佛指长。     

In vivo metabolism of a mutant apolipoprotein, apoA-IIowa, associated with hypoalphalipoproteinemia and hereditary systemic amyloidosis.

Apolipoprotein (apo) A-I is the major protein constituent of plasma high density lipoproteins (HDL). A kindred has been identified in which a glycine to arginine mutation at residue 26 in apoA-I is associated with hypoalphalipoproteinemia and hereditary systemic amyloidosis. We isolated the mutant protein, termed apoA-IIowa, from the plasma of an affected subject and studied its in vivo metabolism compared to that of normal apoA-I in two heterozygous apoA-IIowa subjects and two normal controls. Normal and mutant apoA-I were radioiodinated with 131I and 125I, respectively, reassociated with autologous plasma lipoproteins, and simultaneously injected into all subjects. Kinetic analysis of the plasma radioactivity curves demonstrated that the mutant apoA-IIowa was rapidly cleared from plasma (mean fractional catabolic rate [FCR] 0.559 day-1) compared with normal apoA-I (mean FCR 0.244 day-1) in all four subjects. The FCR of normal apoA-I was also substantially faster in the heterozygous apoA-IIowa subjects (mean FCR 0.281 days-1) than in the normal controls (mean FCR 0.203 days-1). Despite the rapid removal from plasma of apoA-IIowa, the cumulative urinary excretion of its associated radioactivity after 2 weeks (44%) of the injected dose) was substantially less than that associated with normal apoA-I (78% of injected dose), indicating extravascular sequestration of radiolabeled apoA-IIowa.(ABSTRACT TRUNCATED AT 250 WORDS)     

Metabolic and physiological response of the rabbit to continuous and intermittent treadmill exercise

Our knowledge of the effects of exercise on the heart is limited by the predominant use of rats as an animal model. The rabbit has many advantages over the rat as an animal model to study. However, little work has characterized its capacity to exercise. The purposes of the present study were to determine if the rabbit could (i) learn to run on a motor-driven treadmill at relatively high speeds using different exercise protocols, and (ii) characterize the various physiological and metabolic responses of the rabbit to acute bouts of exercise. We found that female New Zealand white rabbits had the capacity to run continuously on the treadmill for up to 21 min at 20 m/min until exhausted. Continuous, endurance-type exercise resulted in significant elevations in body temperature, heart rate, and plasma lactate levels. Plasma triglyceride concentration decreased as a function of this type of running whereas plasma glucose levels were unchanged. Twenty-four hours after a bout of running, plasma creatine phosphokinase activity was significantly elevated. The rabbits also had the capacity to learn to run using an intermittent, higher speed protocol. These physically untrained animals could achieve speeds of up to 70 m/min for 10 bouts of 15 s run/30 s rest. Their metabolic and physiological responses to this protocol were similar to those of continuous running with the following exceptions. The decrease in plasma triglyceride was less marked and the increase in plasma lactate was greater after intermittent exercise. Glycogen content of the rabbit vastus lateralis muscle was also significantly depleted after exhaustive, intermittent exercise.(ABSTRACT TRUNCATED AT 250 WORDS)     

氨基酸酯水解酶产生菌的筛选及其合成头孢立新的研究

From ten genera and 146 bacterial strains, 22 strains producing alpha-amino acid ester hydrolase were selected. Among them, AS 1.586 and 41-2 were the best. The optimal conditions for synthesis of cephalexin by pseudomonas aeruginosa 1.204 were investigated. The optimal pH and temperature for enzymatic synthesis reaction was pH 6.8 and 25 degrees C, respectively. By using 1% 7-ADCA, 3% PGME and 4% biomass, about 70% of 7-ADCA was converted to cephalexin under the mentioned conditions.     

益生菌调控肠道屏障功能预防家禽球虫病的研究进展

球虫病给养禽业带来巨大经济损失,人们对绿色健康食品的迫切需求使球虫病的防控面临新的挑战.伴随世界"禁抗"进程的不断推进,家禽养殖业亟需一种安全有效的新型抗球虫方法.益生菌可竞争性排斥病原菌定殖以防止球虫病继发感染,可刺激宿主抗菌肽、黏蛋白和紧密连接蛋白的分泌以抵御球虫入侵,还可激活免疫反应以增强机体抗球虫感染的能力.本...