满天香精油化学成分的研究

采用Finngan-4510型毛细管气相色谱/质谱/电子计算机联用(GC/MS/DS)技术,辅以~1H NMR,~18C NMR和化学的手段,对广西龙州产满天香精油进存定性定量分析,分离出37个组分,鉴定了其中26个,占精油总量的97.40％。其主要成分为薄荷酮(51.09％)、异满天酮(7.95％)、(+)-新薄荷醇(19.42％)、枞油烯(5.71％)、薄荷醇,β-水芹烯等。薄荷香是一种富含薄荷酮、薄荷醇的新资源植物。     

黄根豆的核型分析

本文首次对单种属植物黄根豆(Chrysoirhiza adenotricha T.Chen)进行了核型分析,其核型公式为K(2n)=22=22m,并确认黄根豆属(Chrysorhiza)的染色体基数为X=11。     

蓝藻型富营养湖泊藻量的昼夜变化节律

杭州西湖为蓝藻型富营养湖泊,根据1980年9月及11月二次昼夜分层采样调查,该湖浮游藻在一昼夜中有二次上下垂直移位,使近表层藻量形成规则或不规则的双峰型昼夜变化曲线,双峰分别出现在日照开始与日落后2h左右,认为昼夜光暗交替与其昼夜变化有一定相关关系,同时,双峰的形成与蓝藻门优势藻种对光照强度的适应性能相关。文中对其优势藻种的浮沉与日照关系作了讨论。     

美洲蜚蠊机械感受器输出信号的计算机分析

对蜚蠊单个机械感受器诱发反应峰电位的历程及幅度,使用系列分析、栅分析、时序分布、累加密度函数、栅—频分析、特征参数的伪三维隐线显示、峰电位幅度概率密度函数、峰电位间隔概率密度函数等分析方法,获得较多的神经信号间隔编码信息,以揭示刺激和反应之间的复杂关系。峰电位间隔和栅—频分析图由函数经曲线拟合后,分别求得描述其动态过程的时间常数τ_1,τ_2和τ_3,应用上述多种分析显示方法,使研究者更为直观地观察和定量描述刺激—反应间的动态关系。     

用TOPSIS方法评价黄土丘陵区草场质量的研究

一、自然概况黄土高原位于我国西北部,西起青海日月山,东抵山西太行山,北至晋陕长城,南达甘陕秦岭,构成一个独具特色的、比较完整的自然区域,其地理范围大致是北纬34°—41°,东经103°—113°之间。高原到处有起伏的黄     

Purification and characterization of antifreeze proteins from larvae of the beetle Dendroides canadensis

Summary Four antifreeze proteins (AFPs) were purified from larvae of the beetle Dendroides canadensis. The AFPs are similar in amino acid compositions, having high contents of hydrophilic amino acids (45–55 mol%) and cysteine (16 mol% Cys). Approximately half of the Cys residues form disulfide bridges, and both the disulfide bridges and free sulfhydryls are essential for activity. The N-terminals of the AFPs are blocked. The pH optimum of the AFPs is 7.8, but major loss of activity occurred only at very high pH (12.0). The detergents SDS and Triton X-100 did not inactivate the AFPs. Circular dichroism spectra indicate the presence of both and secondary structures in the AFPs, in addition to a large random structure component.Abbreviations AFP antifreeze protein - CD circular dichroism - DTT dithiothreitol - HPLC high pressure liquid chromatography - PAGE polyacrylamide gel electrophoresis - PAS periodic acid Schiff - SDS sodium dodecyl sulfate - TFA trifluoroacetic acid     

The pharmacological characterization of 5-HT3 receptor binding sites in rabbit ileum: Comparison with those in rat ileum and rat brain

We have further characterized the 5-HT₃ receptors in rat and rabbit tissues by evaluating the binding of the 5-HT₃ receptor ligand, [³H]GR67330 to homogenates of rabbit ileum, rat ileum and rat brain (entorhinal cortex). In each tissue specific [³H]GR67330 binding represented a single saturable, high affinity site (K_d = 0.14, 0.18, 0.076 nM in rabbit ileum, rat ileum and rat brain respectively). The densities of sites present in rabbit and rat ileum were similar to that present in rat brain (B_max = 63, 47, 72 fmol/mg protein in rabbit ileum, rat ileum and rat brain respectively).

In each tissue, 5-HT₃ receptor agonists and antagonists potently competed for [³H]GR67330 binding. Derived inhibition constants were similar in rat ileum and brain. However marked differences in IC₅₀s were apparent for rabbit ileum compared with rat brain or ileum. These were most apparent with agonists. Thus, mCPBG [1-(meta-chlorophenylbiguanide)], phenylbiguanide, 5-HT and 2-methyl 5-HT were at least 5 times less potent to inhibit [³H]GR67330 binding in rabbit ileum than rat brain. The most pronounced differences were evident with phenylbiguanide and mCPBG which were 70 and 300 times less potent in the rabbit ileum respectively compared with the rat tissues. These differences were unlikely to be due to depletion effects because tissue combination experiments (rabbit ileum and rat brain) yielded biphasic inhibition curves for phenylbiguanide with affinities for each component similar to those in the individual tissues. Antagonist affinities also varied between the rabbit and rat tissues, although less markedly. Amongst the antagonists, the most marked differences were apparent with SDZ 206–830 and quipazine each being 10 times less potent to inhibit binding to rabbit than rat tissue.

Hill coefficients for inhibition of binding varied with tissue. In rat brain, as previously described for [³H]GR67330, Hill coefficients for agonist (and quipazine) inhibition of binding were greater than unity. This was less marked in rat and rabbit ileum tissues.

The present studies provide further evidence for species variation in 5-HT₃ receptors.     

Structural and transcriptional analysis of a human subtelomeric repeat

A human subtelomeric repeat (designated as the HST repeat) has been isolated and characterized from a yeast artificial chromosome containing one human telomere. This repeat is located immediately adjacent to the telomeric T2AG3 repeats at the extreme termini of the human chromosomes. The DNA sequence of 3.6 kb of the HST repeat has been determined. The HST repeat spans over 3.6 kb in length, and contains one evolutionarily conserved CpG-rich region. The copy number of the HST repeat varies among telomeres. Genomic hybridization experiments suggest that the HST repeat consists of two distinct segments, and the distal portions of the HST repeat are also distributed elsewhere in the genome. In HeLa cells, the HST repeat sequence appears to be transcribed into a 6 kb polyadenylated RNA and a variety of non-polyadenylated RNA species.     

心房钠尿肽（ANP）对大鼠卵巢细胞生成雌激...

Isolated ovarian corpus luteal cells and granulosa cells of rat were employed to investigate the effect of alpha-ANP on the secretion of progesterone and estradiol. The contents of the steroid hormones are determined by RIA. The results showed that 0.1-10 ng/ml ANP promoted progesterone production in a dose dependent manner. alpha-ANP also enhanced progesterone production by granulosa cells, but not estradiol. It seems that the effect of alpha-ANP on ovarian steroidogenesis is a direct one.