黄土丘陵沟壑区水平梯田改土培肥增产技术措施体系

黄土丘陵沟壑区水平梯田改土培肥增产技术措施体系刘东海赵廷宁（宁夏西吉县农业局７５６２００）（北京林业大学水土保持学院１０００８３）赵国杰（宁夏西吉县农业技术推广站７５６２００）ＴｅｃｈｎｉｑｕｅｓｏｆＳｏｉｌＩｍｐｒｏｖｅｍｅｎｔａｎｄＹｉｅｌｄＩｎ...     

无性系植物种群生态学研究进展及有关概念

无性系植物种群生态学研究进展及有关概念刘庆钟章成（中国科学院成都生物研究所,６１００４１）（西南师范大学生物系,重庆６３０７１５）ＡｄｖａｎｃｅｓｉｎＥｃｏｌｏｇｉｃａｌＲｅｓｅａｒｃｈｏｆＣｌｏｎａｌＰｌａｎｔＰｏｐｕｌａｔｉｏｎａｎｄＳｏｍｅＲｅ...     

我国自然保护区的生态旅游开发

我国自然保护区的生态旅游开发袁兴中,刘红,高天刚（山东曲阜师范大学２７３１６５）ＤｅｖｅｌｏｐｍｅｎｔｏｆＥｃｏｔｏｕｒｉｓｍｉｎＮａｔｕｒａｌＲｅｓｅｒｖｅｓｏｆＣｈｉｎａ￥ＹｕａｎＸｉｎｇｚｈｏｎｇ;ＬｉｕＨｏｎｇ;ＧａｏＴｉａｎｇａｎｇ（Ｑｕｆ...     

神经生长因子在6－OHDA化学性去交感神经中的保护作用

本实验用６－ＯＨＤＡ造成成年小白鼠领下腺化学性去交感神经,观察了神经生长因子对该神经的保护作用。６－ＯＨＤＡ（１５ｍｇ／ｋｇｉｐ）处理后２４ｈ腺体内去甲肾上腺素（ＮＥ）含量降至正常水平的２％以下。若在６－ＯＨＤＡ处理同时开始多次给予神经生长因子（ＮＧＦ）,则ＮＥ残留量明显提高。减小６－ＯＨＤＡ剂量至１０ｍｇ／ｋｇ,ＮＥ残留量增加,同时ＮＧＦ的作用亦较用６－ＯＨＤＡ１５ｍｇ／ｋｇ时更为显著。若提前２４ｈ给予ＮＧＦ,尽管仍显著提高ＮＥ残留量,但程度却显然低于与６－ＯＨＤＡ同时给予者。以上结果表明外源性ＮＧＦ对６－ＯＨＤＡ造成交感神经化学性损毁有保护作用,此作用与神经受损的严重程度以及ＮＧＦ处理时间有关。     

对分子置换法中积分半径选取方法的探讨

通过对晶胞中帕特逊向量的统计分布的研究,从理论上阐述了根据模型结构单元的线度确定旋转函数的积分半径这种作法的合理性,并且指出了估算积分半径取值范围的具体方法,以及自身旋转函数与交叉旋转函数的积分半径取值范围的区别。经过我们将此方法应用于酚胰岛素Ｂ链羰端六肽胰岛素的旋转函数求解,计算结果证实了这种积分半径的估算方法的可靠性。     

脱落酸对植物线粒体膜生物物理特性的影响

采用１,６－二苯基－１,３,５－已三乙烯（ＤＰＨ）荧光偏振法和中性红法分别研究了脱落酸（ＡＢＡ）对玉米黄化芽及大豆子叶离体线粒体膜的微粘度（η）、表面电位（ψ）等生物物理特性的影响。结果表明：ＡＢＡ有降低线粒体膜的微粘度及提高线粒体膜的表面电位作用,并导致呼吸速率升高,呼吸控制和氧化磷酸化偶联下降。ＡＢＡ对线粒体膜微粘度的作用具有浓度饱和效应;ＡＢＡ对线粒体膜表面电位的提高作用,因植物不同而有差异,对玉米的作用要大于对大豆的。追踪线粒体Ａ（３５０）值的变化,还证实,ＡＢＡ提高了大豆线粒体的Ａ（３５０）值,即导致大豆线粒体的相互聚集（ａｇｇｒｅｇａｔｉｏｎ）。     

大鼠颈上神经节烟碱电流的整流及失敏

在培养的新生大鼠颈上神经节交感神经元标本上,用全细胞膜片钳技术研究了烟碱型乙酰胆碱受体（ｎＡＣｈＲ）通道的整流及失敏现象。烟碱激动剂引起的全细胞电流在膜电位为负值时随膜电位呈线性改变,而在膜电位达＋６０ｍＶ时仍不出现外向电流,表现出强烈的内向整流。ｎＡＣｈＲ通道电流存在失敏现象,即持续恒压喷射激动剂所引起的全细胞电流随时间呈指数衰减,不能保持在峰值水平,失敏随激剂浓度呈量效关系,膜电位的超极化也加     

Structure of the growing telomeres of Trypanosomes

We have developed a method for the molecular cloning of DNA adjacent to chromosome ends (telomeres). A recombinant DNA clone obtained from the telomeres of the protozoan Trypanosoma brucei contains large stretches of the repeat (CCCTAA)n. This repeat is flanked by a larger subtelomeric repeat (29 bp in one case). These repeats account for the presence of large DNA stretches not cut by restriction enzymes downstream of telomeric VSG genes. All telomeres analyzed thus far (more than 30) grow by approximately 6 bp per trypanosomal division and contract by occasional large deletions. Our results suggest that growth is due mainly to addition of CCCTAA units.     

Phenobarbital enhances 2',5'-oligoadenylate synthesis in rat liver nuclei

Treatment of rats with phenobarbital for three days greatly increases the activity of 2,5 oligoadenylate synthetase in liver nuclei. Analysis of 2',5'-oligoadenylates synthesized in vitro showed that nuclei from both phenobarbital-treated and control rats synthesized 2',5'-oligoadenylates ranging from di- to hexamers. However, nuclei from drug treated rats showed a two fold increase in trimer and tetramer synthesis and a three-four fold increase in longer chained oligoadenylates. There was no change in the nuclear 2'-phosphodiesterase activity as the result of phenobarbital treatment, This activity remained low in nuclei from either the treated or the control rats. To our knowledge, this is the first report on phenobarbital affecting the liver 2',5'-oligoadenylate system.     

Comparative Cytochrome Oxidase and Superoxide Dismutase Analyses on Strains of Azotobacter vinelandii and Other Related Free-Living Nitrogen-Fixing Bacteria

Quantitative N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD) oxidase and superoxide dismutase (SOD) analyses were performed on representative organisms of the family Azotobacteraceae. Azotobacter vinelandii, Azotobacter chroococcum, Azotobacter paspali, and Derxia gummosa exhibited high quantitative TMPD oxidase activities, and their extracts possessed very active and electrophoretically homogeneous (single gel band) Fe-type SODs. Azomonas macrocytogenes extracts had similar single Fe-type SODs, and their cells exhibited no TMPD-dependent cytochrome oxidase activity. Nitrogen-fixing cells of Beijerinckia indica, Beijerinckia derxii, and Beijerinckia mobilis exhibited minimal TMPD oxidation capabilities (rates equivalent to the TMPD autooxidation reaction), and these extracts also possessed very active SODs but only of the Mn metallotype.