疏花毛萼香茶菜的二萜成分

从疏花毛萼香茶菜叶的乙醚提取物中一共分得七个二萜化合物,其中四个经各项光谱数据证明它们分别为毛萼乙素(1),毛萼晶甲(2),毛萼晶乙(3)和冬凌草素(4)。     

七种云南地衣植物的化学成分

本文报道分属于三个科的七种云南产地衣植物的化学成分。这些植物是亚洲树发(Alectoria asiatica DR.)、沟树发(Alectoria sulcata Nyl.)、长茎松萝(Usnea longissimaAch.)、胡子松萝(Usnea comosa(Ach.)Rohl.)、林石蕊(Cladonia arbuscula(Rabh.)Rabh.)、砖孢发(Oropogon loxensis(Fee.)Th.Fr.)和卷梢雪花衣(Anaptychiaboryi(Fee.)Mass.)。根据光谱数据测定,其化学成分为:松萝酸(Usnic acid)(1),维任西酸(Virensic acid)(2),赤星衣酸乙酯(Ethyl haematommate)(3),瑞藏酸(Rhizonic acid)(4),赤星衣酸(Haematommic acid)(5),扁枝衣酸乙酯(Ethyleverninate)(6),黑茶渍素(Atranorin)(7)和泽屋萜(Zeorin)(8)。上述资料,对开发利用这些植物资源提供了科学依据。     

A high affinity,calmodulin-responsive (Ca2+ + Mg2+)-ATPase in isolated bone cells

Although acute alterations in Ca²⁺ fluxes may mediate the skeletal responses to certain humoral agents, the processes subserving those fluxes are not well understood. We have sought evidence for Ca²⁺-dependent ATPase activity in isolated osteoblast-like cells maintained in primary culture. Two Ca²⁺-dependent ATPase components were found in a plasma membrane fraction: a high affinity component (half-saturation constant for Ca²⁺ of 280 nM, $\text{V}{}_{\mathrm{<mtext>max</mtext>}}$ of 13.5 nmol/mg per min) and a low affinity component, which was in reality a divalent cation ATPase, since Mg²⁺ could replace Ca²⁺ without loss of activity. The high affinity component exhibited a pH optimum of 7.2 and required Mg²⁺ for full activity. It was unaffected by potassium or sodium chloride, ouabain or sodium azide, but was inhibited by lanthanum and by the calmodulin antagonist trifluoperazine. This component was prevalent in a subcellular fraction which was also enriched in 5′-nucleotidase and adenylate cyclase activities, suggesting the plasma membrane as its principal location. Osteosarcoma cells, known to resemble osteoblasts in their biological characteristics and responses to bone-seeking hormones, contained similar ATPase activities. Inclusion of purified calmodulin in the assay system caused small non-reproducible increases in the Ca²⁺-dependent ATPase activity of EGTA-washed membranes. Marked, consistent calmodulin stimulation was demonstrated in membranes exposed previously to trifluoperazine and then washed in trifluoperazine-free buffer. These results indicate the presence of a high affinity, calmodulin-sensitive Ca²⁺-dependent ATPase in osteoblast-like bone cells. As one determinant of Ca²⁺ fluxes in bone cells, this enzyme may participate in the hormonal regulation of bone cell function.     

MICROSPECTROPHOTOMETRIC ANALYSIS OF NUCLEAR DNA IN CHARA ZEYLANICA

Microspectrophotometric analysis of the DNA content of nuclei in various parts of Chara zeylanica Willd. revealed that the amount of DNA in the nucleus of an internodal cell equals twice the amount of DNA in the nucleus of a sperm, while the half-anaphase stage of the same nodal cells contains the same amount of DNA as the nuclei of the male gametes. The DNA content of the nuclei of internodal cells may rise as much as 50 times higher than that of the gametes. However, in the oldest (most basal) internodal cells, the DNA content of the minute nuclei falls again to the basic (1 C) amount. Measurements of sister nuclei derived by amitosis indicated that both nuclei have equal amounts of DNA; this was interpreted as further evidence that amitosis is not a disorganized process or manifestation of degeneration. The bearing of these analyses on the question of the site of meiosis in these plants is discussed.     

Behaviour of photosynthetic products associated with growth and grain production in the rice plant

Summary A study of the behaviour of the photosynthetic products assimilated at different growth stages was conducted in the field and in the greenhouse using C¹⁴ tracer.In general, the assimilated carbon is translocated to and accumulates in the growing organs. The carbon assimilated at the maximum tiller number stage is distributed mostly to the lower leaves. The carbon assimilated at the booting stage is distributed mostly to the spikelet, certain leaf sheaths and culms. The carbon accumulated in the form of carbohydrates in the leaf sheaths and the culm before flowering is retranslocated to the panicle after flowering. However, because of the consumption by respiration, the efficiency of this type of carbohydrate in grain production is not very high. The carbon assimilated after flowering accumulated mostly and efficiently in the brown rice.The release of the assimilated carbon as CO₂ is most intense immediately after assimilation. Thirty-five to 60 per cent of the assimilated carbon is consumed through respiration under the conditions of this experiment. As the carbon, which is in the form of sugars, rapidly changes to other forms, and also is consumed by respiration, the consumption declines rapidly. The retention percentage of assimilated carbon decreases as mutual shading increases.The large proportion of carbon released through respiration indicates the importance of studies on the significance of respiration in relation to growth.A portion of the thesis for the Master of Science degree submitted by Mr. Shen Lian to the Graduate School, University of the Philippines, College of Agriculture.     

生物素标记寡核苷酸探针探测扩增的病理性突变珠蛋白基因

用末端转移酶催化生物素核苷酸底物(Biotin-ll-dUTP)共价连接在合成的寡核苷酸3’羟基末端,从而合成了两种寡核苷酸探针(β~T_(41-42)及β~A_(41-42))。用它们分别与克隆化扩增的正常和突变的β—珠蛋白基因片段杂变。结果表明该探针都具有与~(32)P探针相似的特异性,其杂交的灵敏度为2—3pg(特异序列)。进而将探测HbS基因的正常和异常两种寡核苷酸19聚体(β~A_6和β~S_6)用~(32)P和生物素分别标记;将HbS杂合子病人的白细胞DNA经聚合酶链反应(PCR)法扩增,并以含正常β—珠蛋白基因的DNA片段作对照,与两种探针分别进行斑点杂交。所得结果完全一致;Hbs杂合子DNA对正常和异常探针都显出杂交信号,而正常DNA只与β~A探针显杂交信号。     

三乙醇胺基强碱性聚苯乙烯树脂共价固定胰酶的研究

用多孔强碱型三乙醇胺基聚苯乙烯阴离子交换树脂做为载体,用CNBr与载体上的多羟基作用共价偶联了胰酶。红外光谱表明:其共价偶联反应机理与用CNBr活化多糖类载体并接酶的机理相类似。最适偶联条件研究表明:CNBr用量增多,酶蛋白载量增加。但比活下降。偶联pH为10时,固定化酶有适宜的载量和较高的比活。由于胰酶水解蛋白反应释放出H~+质子,这些质子在载体内积累,使微环境内H~+质子浓度增加,进而使得固定化胰酶的pH—活性曲线在pH9～11范围内未出现下降。在变温和60℃恒温下对固定化酶的热稳定性测试表明:固相酶的热稳定性比天然酶的热稳定性有所提高。     

Stereoselective high-performance liquid chromatographic assay for propranolol enantiomers in serum

A simple and sensitive stereoselective high-performance liquid chromatographic assay for the quantitation of propranolol enantiomers in serum is described. The method involves conversion of the propranolol enantiomers to diastereomeric urea derivatives by reaction with the chiral reagent (+)-phenylethylisocyanate, followed by chromatographic separation of the diastereomeric products. Conditions of the derivatization reaction were optimized to achieve rapid and quantitative yield with either of the enantiomers. Baseline resolution of the diastereomers was achieved on a reversed phase C₈ column with an isocratic mobile phase. Fluorescence detection afforded an absolute on-column detection limit of 100 pg. The assay has been applied to pharmacokinetic studies in humans and small laboratory animals.