流式细胞计的研制

流式细胞计是近年发展起来的一种综合应用光学机械,电子学,流体动力学,激光和计算机的高技术生物医学仪器。它在生物学基础研究和临床医学研究中有广泛的应用。我们最近研制成功国内首台多参数流式细胞计,并已通过中国科学院院级鉴定。本文介绍该仪器的原理,主要结构与技术要点和使用结果等,它将有助于我国流式细胞术及其应用研究工作的开展。     

对害虫具自然控制能力的益害比指标模型研究

在害虫测报和防治工作中,经常要考虑天敌与害虫数量的比例问题,以决定是否需对害虫进行防治或决定相应的防治措施。如果采取防治措施过早,不能充分发挥天敌的自然控制作用,则会浪费人力物力;如采用化防还会加     

六种选矿药剂对藻类的毒性比较

本文评价了六种选矿药剂对藻类的毒性效应,它们对斜生栅藻的毒性大小排列顺序是:二号油>Fu>0145>Yx>MPA>S-808,96h-EC_(50)值分别为41.2,50.1,82.0,177.8,198.2和900ppm。六种选矿药剂对藻类毒性最大的是二号油,毒性最小的是S-808。对藻类细胞形态的观察结果表明,0145对藻类的细胞形态有轻度的致畸效应,在其它五种药剂的培养物中,均未发现畸变细胞。在室温下存放10d后MPA,0145和二号油,毒性明显下降,其下降速率的顺序是:MPA>0145>二号油。藻类对S-808具有净化脱色作用,100ppm浓度的S-808溶液经藻类作用32d后,其色度可减少48％,作用62d和93d,色度分别降低54％和58％。0145抑制藻类的光合放氧,经50,100和200ppm浓度的0145处理4h后,与对照相比,藻类的光合放氧速率分别下降15、34和36％。     

大果木姜子的甘油三酯组成

采用光谱法和胰酯酶分解法对大果木姜子油酯中分得的结晶C—I组成进行了分析,结果表明C—I是由11种甘油三酯组成。其中2-位为月硅酸的甘油三酯占91.80％,1,3-位脂肪酸主要为癸酸和月桂酸,甘油三酯的组成中,CLC占62.24％,LLC占24.50％。     

染色体辐射效应的微机检测 Ⅱ断片率 微核率与细胞畸变率间的相关性检测

本文继前文后,按照设计的线性回归程序在“IBM—PC/XT”微型计算机上,进一步检测了断片率、微核率与细胞畸变率之间的相关性,肯定了微核测定法,断片测定法可以替代染色体畸变分析法。     

Molecular cloning and characterization of the gene encoding the adenine methyltransferase M.CviRI from Chlorella virus XZ-6E.

The gene encoding the DNA methyltransferase M.CviRI from Chlorella virus XZ-6E was cloned and expressed in Escherichia coli. M.CviRI methylates adenine in TGCA sequences. DNA containing the M.CviRI gene was sequenced and a single open reading frame of 1137 bp was identified which could code for a polypeptide of 379 amino acids with a predicted molecular weight of 42,814. Comparison of the M.CviRI predicted amino acid sequence with another Chlorella virus and 14 bacterial adenine methyltransferases revealed extensive similarity to the other Chlorella virus enzyme.     

α—人心房钠尿因子对离体豚鼠心肌收缩力和动作电位...

The effect of alpha-hANF on contractile force and action potential duration (APD) of isolated myocardium in guinea pig was investigated. At the level of 20 nmol/L and 40 nmol/L alpha-hANF, the contraction amplitude and rate of contraction phase decreased to a remarkable extent. And at 40 nmol/L, APDs were shortened significantly 20 min after alpha-hANF. The results suggest that there exists a direct inhibitory effect of alpha-hANF on myocardial contractile force and action potential duration.     

The refined 2.3 A crystal structure of human leukocyte elastase in a complex with a valine chloromethyl ketone inhibitor

The stoichiometric complex formed between human leukocyte elastase and a synthetic MeO-Suc-Ala-Ala-Pro-Val chloromethyl ketone inhibitor was co-crystallized and its X-ray structure determined, using Patterson search methods. Its structure has been crystallographically refined to a final R value of 0.145 (8.0 and 2.3 A). The enzyme structure is very similar to that recently observed in a complex formed with the ovomucoid third domain from turkey [(1986) EMBO J. 5,2453-2458]. The rms deviation of all alpha-carbon atoms is 0.32 A. The peptidic inhibitor is bound in a similar overall conformation as the ovomucoid binding segment. Covalent bonds are formed between Val-P1 of the inhibitor and His-57 NE2 and Ser-195 OG of the enzyme. The carbonyl carbon is tetrahedrally deformed to a hemiketal. The valine side chain is arranged in the S1 pocket in the g-conformation.     

Methodology for enumeration of coliphages in foods.

The effects of eluent composition, pH, and chaotropic agents on the recovery of T2, MS2, and indigenous coliphages from various foods were investigated. Additionally, methods of sample suspension and clarification were evaluated for coliphage recovery and application to various foods. Clarified sample suspensions were assayed for coliphages with a modified agar layer technique and appropriate Escherichia coli hosts. Centrifugation and polypropylene mesh filtration were more rapid and effective than glass wool filtration for clarification of sample suspensions and subsequent recovery of coliphages. Blending, stomaching, and shaking procedures were generally comparable for sample liquefaction and release of coliphages from foods. Complex basal eluents, EC medium and 1% casein, were generally more effective than a less complex eluent, phosphate buffer, for elution of coliphages from foods. For most foods, incorporation of sodium chloride or chaotropic agents, i.e., sodium trichloroacetate, urea, Tween 80, Triton X-100, and sodium nitrate, into basal eluents did not enhance recovery of coliphages. Indigenous coliphage recovery was not affected by sample suspension pH over a range of 6.0 to 9.0. With an optimal procedure, i.e., EC medium eluent, blending, and centrifugation, the recovery of T2 and MS2 ranged from 48 to 81% and from 58 to 100%, respectively, depending on the food type.