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,     

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.     

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.     

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     

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.     

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     

蛹虫草研究进展*

蛹虫草(Cordyceps militaris)作为一种药(食)用菌已经被广泛接受,在药理作用、有效成分、人工栽培等方面得到了广泛而深入的研究,具有重要开发价值。依据近年来的有关研究成果,就以上3个方面的研究进展状况展开论述,为蛹虫草进一步的研究与开发提供参考。     

抗病毒免疫研究进展*

抗病毒免疫的机制极其复杂,宿主的免疫系统需要经过抗原肽的加工提纯、淋巴细胞活化、抗体和细胞因子的产生等一系列步骤才能最终清除病毒的感染。从蛋白酶体在病毒肽抗原加工中的作用、免疫支配效应的意义、CTL杀伤病毒感染细胞的机制、细胞因子的作用和免疫逃逸机制等方面阐述了抗病毒免疫机制,对于病毒的防治将是十分重要的。     

论凯里组*

记述了黔东南凯里组三叶虫的地层分布 ,讨论了三叶虫的分带 ,根据三叶虫地层分布情况 ,将凯里组与国内外同期地层进行了对比 ,指出了凯里生物群与布吉斯页岩生物群 ,斯潘塞页岩生物群出现的顺序 ,对于深入研究凯里生物群与其它生物群的演化具有重要意义。     

螺旋藻的纯化*

观察了螺旋藻生长过程中藻丝和杂菌的生长规律,发现中性细菌和碱性细菌的数量始终是藻丝的10⁵～10⁶倍。采用常规的稀释平板法、毛细管法和挑单藻法均无法可靠地获得无菌纯藻。设计用低速离心法洗涤下沉性藻丝,用过滤法洗涤上浮性藻丝,对藻丝进行预处理洗去大量杂菌;对迁移性和非迁移性藻株分别采用夹层法和平板法纯化藻株,使得单根藻丝在平板上形成藻落,获得无菌纯藻。