31P-NMR研究生物活组织

NMR在生物学中的应用是从70年代发展起来的。 ³¹P-NMR法因其共振谱线简单明了,灵敏度高,能无损伤地监控生物活组织内的与能量代谢密切相关的含磷化合物浓度的动态变化,而成为在生理条件下测定组织内部动力学参量的重要方法。本文通过介绍离体灌流标本和在体组织器官的 ³¹P-NMR的具体应用实例,集中反映了在这一领域研究的概况和新近的研究成果。     

A 31P-NMR study of mono- and dimagnesium complexes of adenosine 5′-triphosphate and model systems

³¹P-NMR chemical shifts and spin-lattice relaxation times of ATP (adenosine 5′-triphosphate), ribose 5′-triphosphate and tripolyphosphate show closely similar behaviour in aqueous solution at pH 7.5 on titration with Mg²⁺. The results are interpreted in terms of formation of 1 : 1 and 2 : 1 (dimagnesium) complexes with Mg²⁺ bound exclusively to the triphosphate chain. Stability constants for these complexes are reported. It is suggested that the predominant form of the 1 : 1 complexes has Mg²⁺ bound in tridentate manner (via non-bridging oxygen) to the α, β and γ phosphorus atoms; whilst that of the 2 : 1 complexes has each Mg²⁺ bound in bidentate manner, one to the α and β, and the other to the β and γ, phosphorus positions.     

L7811鼠腹水肿瘤细胞 31P核磁共振的研究

用 ³¹P核磁共振技术(³¹P-NMR)研究了L₇₈₁₁鼠腹水肿瘤细胞和615系鼠胸腺细胞(正常对照细胞)。结果发现在肿瘤晚期阶段,L₇₈₁₁腹水肿瘤细胞的含磷化合物未进入完全不活跃状态。此外,腹水肿瘤细胞的磷脂组成与含量亦有明显改变。因此, ³¹P-NMR谱可做为观察肿瘤细胞内能量生成和某些磷脂合成宏观动态过程的一项参考指标。     

A comparison of the disposition of 14C-Δ9-tetrahydrocannabinol and 3H-Δ9-tetrahydrocannabinol

Preliminary experiments suggested that total levels of radioactivity disappeared from the blood of male, Fischer rats much more rapidly following intragastric administration of ¹⁴C-Δ⁹-tetrahydrocannabinol (¹⁴C-THC) than ³H-THC. Collaborative experiments at the Stanford Research Institute (SRI) and the Research Institute on Alcoholism (RIA) verified and characterized the initial observations. In rats that had food available throughout the experiments, the concentrations of total ³H and ¹⁴C in fresh plasma reached a maximum at 2 – 4 hours after treatment with ³H-THC plus ¹⁴C-THC. Thereafter, ¹⁴C levels fell while ³H levels decreased very slowly or not at all. In fasted rats, peak plasma concentrations of both isotopes were not attained until about 8 hours following drug administration. The concentrations of ¹⁴C then decreased more rapidly than ³H. The differences between the plasma disappearance curves for ¹⁴C and ³H were not dependent upon the method of blood collection or the techniques of isotope counting. However, when plasma or whole blood samples were dried before radioisotope analysis, the difference between ¹⁴C and ³H concentrations was virtually abolished in fed and fasted rats. Experiments suggest that tritiated water, produced during the metabolism of ³H-THC, may be responsible for the prolonged maintenance of high ³H levels in the blood.     

乌塘鳢对51Cr、60Co、131I、141Ce的吸收和积累

本文以河口底栖鱼类,不具鳞片,对环境适应力强的乌塘鳢为材料,研究它们以摄食和渗透两种方式对~(51)Cr,~(60)Co、~(131)I和~(141)Ce的吸收。为了观察在渗透吸收期间个体的差异,测定了单条活鱼的放射性。在实验中采用多核素示踪法并用S-80智能多道分析器和Ge(Li)探头测量放射性。 结果发现,当~(131)I的浓度为3.4×10~(-7)居里/升时,在10小时内所有的乌塘鳢都被杀死,而~(131)I在鱼体各组织器官的积累是明显的。器官积累核素数量的顺序是~(131)I>~(141)Ce>~(51)Cr,在任何组织器官均未检出~(60)Co。 在渗透吸收实验里,对单条活鱼的测量结果表明,核素是能够通过皮肤的渗透积累在鱼体内,并且存在个体差异。同时表明,生命元素的同位素如~(131)I,~(60)Co容易渗透到鱼体内部器官,而非生命元素的同位素例如~(141)Ce、~(51)Cr的渗透是慢的。 ~(51)Cr、~(60)Co、~(131)I、~(141)Ce是沿海核设施常见的放射性废物成分,有的是具有生态学意义的核素(Goldberg,1957),随着沿海核电站的不断兴建,它们在河口港湾存在的机会越来越多。虽然海洋鱼类和淡水鱼类对它们的浓集有过报道(Hiyama et al.,1964),但河口生物,特别是河口的底栖鱼类对它们的吸收和积累,则研究甚少。 乌塘鳢是生活在河口滩涂的底栖鱼类,适应于半咸淡的水质,     

影响活体内马铃薯晚疫病菌卵孢子产生因素的研究*

研究了不同菌株组合,马铃薯植株茎、叶及接种物中A1和A2菌株孢子囊比例、温度、湿度对卵孢子产生的影响。不同菌株组合产生卵孢子的数量有显著差异;在离体接种情况下,叶片中产生卵孢子数量大于茎中产生卵孢子数量;A1和A2菌株中孢子囊不同比例对卵孢子产生影响很大,当比值为1∶1时卵孢子产生量最大;15℃光照条件下培养,并给侵染叶片持续的水分供应才能产生大量卵孢子;寄主的抗性水平对卵孢子产生有明显的影响,中抗品种上产生卵孢子量最多,高抗品种上产生卵孢子量最少,感病品种上产生卵孢子量居中。     

137Cs和210Pbex示踪黑土区坡耕地

通过在野外28.5 hm²的坡耕地上采集土壤样品,定量评价了利用¹³⁷Cs和²¹⁰Pb_ex研究土壤有机碳(SOC)动态的潜力,以探讨东北黑土区土壤侵蚀对土壤有机碳的影响.结果表明:农耕地土壤¹³⁷Cs、²¹⁰Pb_ex和SOC在平面和垂直深度上均具有相似的分布特征.在平面上,尽管受土壤侵蚀沉积的影响,¹³⁷Cs、²¹⁰Pb_ex面积活度及SOC储量变异很大,但它们具有相同的变化趋势.在垂直断面上,侵蚀区¹³⁷Cs、²¹⁰Pb_ex和SOC在0～25 cm耕层内分布均匀,25 cm以下放射性活度减小,SOC含量也相应下降;沉积区0～100 cm深度上¹³⁷Cs和²¹⁰Pb_ex呈现先增加后减小的分布规律,SOC也具有类似的变化特征.农耕地SOC与¹³⁷Cs、²¹⁰Pb_ex呈显著线性相关,表明它们在黑土区农耕地上具有相似的物理运移特征,¹³⁷Cs和²¹⁰Pb_ex可直接用来定量评价黑土侵蚀下SOC的时空分布特点.     

正常大鼠植入高血压大鼠肾脏后 动脉血压的变化

本实验对12周龄的自发性高血压大鼠(spontaneously hypertensive rat,SHR)及其对照组Wistar Kyoto (WKY)大鼠进行了肾脏移植的研究, 并观察受肾移植大鼠动脉血压的变化以及免疫抑制剂对动脉血压的影响。 用尾套法对接受同窝另一同胞WKY大鼠肾脏移植且存活5周的6只WKY大鼠(A组)及接受SHR肾脏移植且存活5周的6只WKY大鼠(B组)的尾动脉收缩压进行检测, 移植前A、 B两组受肾移植大鼠的尾动脉收缩压分别为18.0±0.93 和18.3±0.68 kPa,无统计学显著差异(P>0.05); 移植后3、 4、 5周时, B组大鼠的尾动脉收缩压显著高于A组大鼠, 移植后5周时, A, B两组大鼠的收缩压分别为19.0±0.71 和23.0±0.69 kPa (P<0.001); 所用剂量的免疫抑制剂CsA对双侧肾脏完整以及右侧肾脏切除的SHR、 WKY大鼠的动脉血压无显著影响。 以上结果表明, SHR的肾脏在高血压的形成中可能起重要作用。     

亚热带人工林松树13C/12C比率和水分利用效率

The ¹³C/¹²Cratio, photosynthetic rate and stomatie conductivity of leaves of Pinus massoniana, Schima superba,Psychotria rubra, Evodia lepta and Rhodomyrtus tomentasa are measured. No significant deviation (at 5% level) is observed between water use efficiencies calculated by these items. The¹³C/¹²Cis 25.41±0.61‰. In average for treerings of Pinus massoniana from 1971 to 1983(n=6), with the maximum in1977 when the lowest precipitation was recorded. The average water use efficiency of Pinus massoniana is 8.28±0.38 in1977—1983, which is higher than that of trees in natural site and might be caused by the changes of solar radiation and water condition. ¹³C/¹²Cratio ana lysis could provide usefull informations for studying water use efficiency of artificial forest.     

基因体外诱变*

综述了基因体外诱变的一般方法和技术,并将其分为不依赖于PCR体外诱变和依赖于PCR体外诱变两大类。着重介绍了基因体外诱变最新突破即DNA　Shuffling技术。     

荧光素酶研究进展*

荧光素酶 (Luciferase)可以分为萤火虫荧光素酶和细菌荧光素酶两大类。萤火虫荧光素酶是分子量为 60～ 64kD的多肽链 ,在Mg²⁺、ATP、O₂ 存在时 ,催化D 荧光素 (D Luciferin)氧化脱羧 ,发出光 (λ =550～580nm)。细菌荧光素酶是含α、β两个多肽亚基的加单氧酶 ,它催化长链脂肪醛、FMNH₂ 和O₂ 的氧化反应 ,发出绿蓝光 (λ =490nm)。萤火虫荧光素酶和细菌荧光素酶     

Antibodies to Pseudomonas testosteroni 3-oxosteroid Δ4-Δ5-isomerase

Antibodies to Pseudomonas testosteroni isomerase have been generated in rabbits immunized with the isomerase. Complexes between the isomerase and antibodies were characterized by double immunodiffusion and by enzymatic assays. The titre of antibodies was determined. The enzymatic activity was totally abolished with increasing antibody concentrations. Antibody-isomerase complexes were inactive. Total immunological identity was observed between the unpurified extract and the pure enzyme either free or bound to a competitive inhibitor. However, the denatured enzyme did not interact with antibodies. Antigenic identy could not be detected between the bacterial antibodies and the bovine adrenocortical isomerase from microsomes.     

Investigations on the Δ23-, Δ24(28)- and Δ25-Sterols of zea mays

The sterols of Zea mays shoots were isolated and characterized by TLC, HPLC, GC/MS and ¹H NMR techniques. In all, 22 4-demethyl sterols were identified and they included trace amounts of the Δ²³-, Δ²⁴- and Δ²⁵-sterols, 24-methylcholesta-5,E-23-dien-3β-ol, 24-methylcholesta-5,Z-23-dien-3β-ol, 24-methylcholesta-5,25-dien-3β-ol, 24-ethylcholesta-5,25-dien-3β-ol and 24-ethylcholesta-5,24-dien-3β-ol. In the 4,4-dimethyl sterol fraction, cycloartenol and 24-methylenecycloartanol were the major sterol components but small amounts of the Δ²³-compound, cyclosadol, and the Δ²⁵-compound, cyclolaudenol, were recognized. These various Δ²³- and Δ²⁵-sterols may have some importance in alternative biosynthetic routes to the major sterols, particularly the 24β-methylcholest-5-en-3β-ol component of the C₂₈-sterols. Radioactivity from both [2-¹⁴C]MVA and [methyl-¹⁴C]methionine was incorporated by Z. mays shoots into the sterol mixture. Although 24-methylene and 24-ethylidene sterols were relatively highly labelled, the various Δ²³- and Δ²⁵-sterols contained much lower levels of radioactivity, which is possibly indicative of their participation in alternative sterol biosynthetic routes. (24R)-24-Ethylcholest-5-en-3β-ol (sitosterol) had a significantly higher specific activity than the 24-methylcholest-5-en-3β-ol indicating that the former is synthesized at a faster rate.     

大鼠SR-BI胞外域与ApoA-I蛋白相互作用的确认*

先以含全长SR-BIcDNA序列的重组质粒pMD18-T-rS为摸板进行PCR反应扩增SR-BI得到胞外域cDNA片段,经测序证明正确后,定向克隆到酵母双杂交表达载体,然后与pGBKT7-ApoA-I质粒共转化酵母细胞,通过报告基因及酵母交配试验确认了SR-BI的胞外域部分和ApoA-I之间的确存,观察到ApoA-I与SR-BI胞外域间的相互作用力比与全长的SR-BI间的相互作用力提高了10%。     

Δ12-脂肪酸脱氢酶基因在大肠杆菌中的表达*

把高山被孢霉 (Mortierellaalpina)和深黄被孢霉 (Mortierellaisabellina)的Δ¹²-脂肪酸脱氢酶基因亚克隆到大肠杆菌表达载体pET21a中 ,获得重组表达载体pMACL12和pMI CL12 ,并用氯化钙方法将重组表达载体转化到大肠杆菌BL21 (DE3)中。筛选阳性克隆进行培养 ,然后分离其细胞膜蛋白 ,并构建体外表达体系 ,同时加入外源性底物油酸进行表达。经气相色谱 (GC)分析表明 ,分别有 17.87%和 17     

鼎湖山地区人类活动对马尾松年轮13C/12C的影响

南亚热带鼎湖山保护区的非核心地带的旅游活动和附近工厂区污染气体的排放,影响了 年轮中的δ＾１３Ｃ值和窃据的δα值。旅游点年轮的δ＾１３Ｃ值自１９６５－１９９２年以年均－０．０２６‰速率下降,１９８０－１９９２年年均下降速率增至－０．０４４‰。工厂点的年轮δ＾１３Ｃ则随时间而递增,气体污染改变了δ＾１３Ｃ值的年际变化图式。１９８０－１９９２年,对照点、旅游点和工厂点空气ＣＯ２浓度年均增高速率分别为０     

琥珀酸发酵研究进展*

琥珀酸在化工和食品行业应用广泛。与传统化学方法相比,微生物发酵法生产琥珀酸具有诸多优点：生产成本具有竞争力;利用可再生的农业资源包括二氧化碳作为原料,避免了对石化原料的依赖;减少了化学合成工艺对环境的污染。主要介绍产琥珀酸微生物的来源和育种,代谢途径和发酵调控机制以及产品回收工艺的进展。