西藏波密古乡地区的主要植物群落及其垂直分布

本文讨论了西藏波密古乡地区的主要植物群落及其垂直分布。 1．根据小带间植物种类相似系数情况,将波密古乡地区南、北坡划成八个植物垂直带 (图1)。 2．描述了七个不同性质的植物群落。各群落分布与水热条件之间的相互关系如图2所 示。 3．由于不同水热条件的影响,各植被带间在植物种数上的差异是比较显著的(表3)。     

各种酵母菌经超低温冻结和融化后的反应

本文报告用液氮超低温(-196℃)冻结和融化后,对酵母菌的影响。34种酵母菌经慢速(冷却速度为1℃/min)冻结后细胞成活率普遍高于快速(冷却速度为450℃/min)冻结。10%甘油和10%二甲亚砜比水在冻结中呈现出显著的保护作用。冻结保藏4个月后,细胞成活率都在11%以上,最高达97%,平均70.4%,而水,最低者仅0.4%,最高87%,平均46.5%。所观察的白地霉 Geotrichum candidum As 2.361,椭圆酿酒酵母 Saccharomyces cere-visiae var.ellipsoideus AS 2.541,八孢裂殖酵母 Schizosaccharomyces octosporus AS 2.1148,其细胞在冻结过程中的形态,最初质壁分离,继之整个细胞收缩,而融化后则可复元.解脂假丝酵母 Candida lipolytica AS 2.1207和2.1405经冻结48小时以上,融化后的细胞悬液直接接种培养后检测脂肪酶活力;酿酒酵母 Saccharomyces cerevtsiae AS 2.399和椭圆酿酒酵母 As 2.541冻结48小时后乙醇发酵力;异常汉逊酵母 Hansenula auomala AS 2.300和 AS 2.470冻结后形成乙酸乙酯的能力,都无明显的减退,而且以甘油作保护剂的细胞,较未经冻结者呈现出稍强的活力。就代谢产物而言,用气相色谱法分析发酵液,乙醇或乙酸乙酯都是很纯的终产物。嗜渗压的固囊酵母 Citeromyces matritensis AS 2.1401和汉逊德巴利酵母 Debaryomyceshansenii AS 2.45冻结后的细胞耐 NaCl 的能力无改变.冷冻真空干燥法保藏菌种,适合的菌类较广,是久经考验的方法。但是对于酵母菌冻干后细胞成活率平均为8.6%,而超低温冻结24小时细胞成活率平均为86.7%,大了10倍。     

氨基酸分析仪测定角屑病患者鳞屑中氨基酸含量

银屑病是皮肤病中最为常见的疾病之一。主要病理变化是角朊细胞角化兴一。本研究以银屑病患者的鳞和为研究对象,测定其水解物中的氨基酸含量,从而探索银屑病的氨基酸含量并进行比较,从而银屑病的氨基酸代谢变化规律,为银的诊治提供理论基础。     

用核糖体DNA的ITS序列探讨裂叶沙参的系统位置——兼论ITS片段在沙参属系统学研究中的价值

本文采用PCR直接测序方法,对来自沙参属全部2组7亚组的10个种和作为外类群的风铃草属2个种的核糖体DNA　ITS片段进行了序列分析。在重点探讨裂叶沙参分类地位的同时,分析了ITS片段序列在沙参属系统发育重建中的价值。结果表明,在沙参属中,ITS片段在长度、GC含量和位点变异量上均比较一致;长度539bp～541 bp,GC含量57％～60％,信息位点只占总位点的3．9～6％。采用PAUP软件进行的系统发育分析表明,裂叶沙参A．lobophylla与大花盘亚组的A．himalayana组成一支,而不是象以往形态学和杂交试验所推断的与泡沙参A．potaninii或A．stenanthina近缘。可见,ITS序列进一步支持将裂叶沙参移出泡沙参复合体甚至移出有齿亚组的推论,但同时也表明将其作为A．stenanthina的近缘种是不适宜的。尽管本研究所测定的类群已涵盖了整个沙参属,但种间序列的两两比较表明,沙参属种间在ITS片段上的分化很小(0.0～3.9％),相比之下,沙参属类群与风铃草属类群间的分化却很高(17.8％～19.2％)。这大概和沙参属起源较晚、遗传分化较小有关。本文还就ITS片段在沙参属和桔梗科系统学研究中的价值进行了讨论。     

Genetic diversity analysis by RAPD in Cathaya argyrophylla Chun et Kuang

Genetic diversity level of Cathaya argyrophylla was confirmed by random amplified polymorphic DNA (RAPD) markers. Seventy five samples (individuals), collected from Hunan and Sichuan provinces of China were used in the study. 21 10-mer oligonucleotide primers detected 106 sites, and 34 (32% ) of them were polymor-phic. The level of genetic variation in C. argyrophylla was lower than those of other conifers, and was considered to be associated with the complexity of habitats. The percentages of polymorphic sites (PPS) in the Hunan and Sichuan pop-ulations were 18% and 25% respectively. 7.99% of genetic variation existed between the two populations; this value was higher than the mean value (6.8%) among populations in conifers displayed by allozyme. Some subpopulations of C. argyrophylla were greatly differentiated because of site mutation and genetic drift. The highest value of genetic dif-ference between subpopulations amounted to 16. 23% . In addition, a concept of diversity coefficient(DC), a value us     

限制性内切酶缓冲液诱导人和家兔染色体显带的研究

用限制性内切酶AluⅠ、缓冲液或空白处理人染色体标本,发现AluⅠ及缓冲液均能诱导出类C和G带,其中缓冲液诱导的类C带频率虽低于酶原液,但明显高于空白对照; 而G带的诱导率无明显差异。此外,用限制性内切酶H ae Ⅲ和 HinfⅠ及其缓冲液处理中国小型白兔外周血染色体标本,也诱导出了相应的类C和G带。 Abstract:C-and G-bands were induced in human chromosome by both AluI and its buffer after treating the samples with AluI,buffer and blank control.The frequence of C-band induced by buffer was lower than that by AluI(P<0.05),but much higher than that by blank control(P<0.001).There was no significant difference among the frequencies of G-band induced by AluI,buffer and blank control(P>0.05).Also HaeIII,and their buffers were capable of inducing C-and G-bands on chromosome of China small-sized domestic rabbits.