桃儿七分布格局与生态适应的初步研究

以云南产桃儿七Ｓｉｎｏｐｏｄｏｐｈｙｌｌｕｍ ｈｅｘａｎｄｒｕｍ（Ｒｏｙｌｅ）Ｙｉｎｇ为研究材料,分析了它的分布格局及生态适应。指出桃儿七是一个分布范围较广、生态适应幅度大的物种;在分布区内它主要出现在具有次生植被的山谷中,个体在居群内的分布格局,由于受到放牧活动的影响而呈聚群式分布,植株常出现在灌木丛下和树根附近。它适应夏秋湿润凉爽,冬季及早春寒冷干燥的气候条件,并具有相应的生长与发育节律。人类     

吴氏手绥螨和长螯肛厉螨2新种记述（蜱螨亚纲：裂胸螨科）

记述裂胸螨科2新种,吴氏手绥螨Cheiroseius wuwenzheni sp.nov.和长螯肛厉螨proctolaelaps longichelicerae sp.nov.     

DAB诱发大白鼠肝癌过程中细胞质膜上酶变化的观察

本实验以二甲基氨基偶氮苯（ＤＡＢ）诱发大白鼠肝癌的动物模型为材料,观察了在诱癌过程中和肝癌形成后大白鼠肝细胞质膜上几种酶活性的变化,用不连续蔗糖密度梯度离心法制备肝细胞质膜,分光光度法对酶活性进行定量测定。实验结果表明,在诱无病癌过程中,肝细胞质膜上５′－ＡＭＰａｓｅ活性上降,γ－ＧＴａｓｅ活性显著升高。γ－ＧＴａｓｅ活性升高幅度与病理变化正相关,并且在诱癌早期就能表现出来。     

GM_3对小鼠腹腔巨噬细胞磷脂代谢转换率的影响

神经节苷脂ＧＭ_３对小鼠腹腔常驻巨噬细胞（Ｒ－Ｍ）和Ｇｅ－１３２体内激活的巨噬细胞（Ｇｅ－１３２－Ｍ）的磷脂代谢转换有显著的影响,当这两种Ｍ在体外用ＧＭ_３处理时,表现出［￣（３２）Ｐ］Ｐｉ和［￣３Ｈ］肌醇参入ＰＩ降低,参入ＰＩＰ、ＰＩＰ_２增加;但在［￣（３２）Ｐ］Ｐｉ和［￣３Ｈ］胆碱参入ＰＣ上,Ｒ－Ｍ与Ｇｅ－１３２－Ｍ不同,即ＧＭ_３促进同位素前体参入Ｒ－Ｍ的ＰＣ,抑制它们参入Ｇｅ－１３２－Ｍ的ＰＣ．以上结果表明ＧＭ３可能提高了ＰＩ或ＰＩＰ的磷酸激酶的活性,致使［￣（３２）Ｐ］ＰＩＰ和［￣（３２）Ｐ］ＰＩＰ_２增多,［￣（３２）Ｐ］ＰＩ减少．激活的Ｍ（Ｇｅ－１３２－Ｍ）本身ＰＣ代谢转换率较Ｒ－Ｍ高,当Ｇｅ－１３２－Ｍ再受ＧＭ_３刺激,ＰＣ代谢转换率降低,这提示ＧＭ_３对激活的Ｍ的ＰＣ代谢转换有调节作用．     

Modulation of myocardial alpha 1- but not beta-adrenoceptors after 90-day tail-suspension

We have previously demonstrated that prolonged simulated microgravity (tail-suspension) leads to cardiac alterations with increased resting heart rate, myocardial degradation changes and attenuated myocardial contractility. The present study investigated the potential role of adrenoceptor mechanisms underlying them. Changes of myocardial alpha 1-adrenoceptor (alpha 1-AR) and beta 1-adrenoceptor (beta-AR) in 90-day tail-suspended rats was investigated by the method of radioligand binding assay and application of Scatchard's method. The results showed significantly decreased quantity of specific binding of 125I-BE[2-beta-(4-hydroxy-3-[125I]indophenyl)-ethylaminomethyltetralone] to alpha 1-AR present in membrane derived from ventricular myocardium of the suspended animals, despite the affinity of the alpha 1-AR to 125I-Be was unchanged. But neither the quantity nor the affinity of beta-AR binding to 125I-Pindolol was significantly altered. In addition, the spontaneously beating rate of isolated right atria from tail-suspended animals showed little change in sensitivity and reactivity to the stimulations of graded phenylephrine (alpha-agonist, measured in the presence of beta-antagonist propranolol) and isoproterenol (beta-agonist), compared with the control rats. There were also no obvious differences of the effects of the isoproterenol on the contractility of isolated left ventricular papillary muscles between the two groups. Since myocardial alpha 1-AR mediated-effects include production of cardiac hypertrophy and enhancement of myocardial glucose uptake and glycolysis, the down-regulation of the alpha 1-AR may be a contributor to the cardiac cellular accumulation and the myocardial degradation changes as found in our tail-suspended rats. The data from this study also suggest that the myocardial beta-adrenoceptors are not affected by the prolonged tail-suspension.     

Desensitization of the skeletal muscle ryanodine receptor: evidence for heterogeneity of calcium release channels.

Ca release channels from the junctional sarcoplasmic reticulum (SR) membranes of rabbit skeletal muscle were incorporated into the lipid bilayer membrane, and the inactivation kinetics of the channel were studied at large membrane potentials. The channels conducting Cs currents exhibited a characteristic desensitization that is both ligand and voltage dependent: 1) with a test pulse to -100 mV (myoplasmic minus luminal SR), the channel inactivated with a time constant of 3.9 s; 2) the inactivation had an asymmetric voltage dependence; it was only observed at voltages more negative than -80 mV; and 3) repetitive tests to -100 mV usually led to immobilization of the channel, which could be recovered by a conditioning pulse to positive voltages. The apparent desensitization was seen in approximately 50% of the experiments, with both the native Ca release channel (in the absence of ryanodine) and the ryanodine-activated channel (1 microM ryanodine). The native Ca release channels revealed heterogeneous gating with regard to activation by ATP and binding to ryanodine. Most channels had high affinity to ATP activation (average open probability (po) = 0.55, 2 mM ATP, 100 microM Ca), whereas a small portion of channels had low affinity to ATP activation (po = 0.11, 2 mM ATP, 100 microM Ca), and some channels bound ryanodine faster (< 2 min), whereas others bound much slower (> 20 min). The faster ryanodine-binding channels always desensitized at large negative voltages, whereas those that bound slowly did not show apparent desensitization. The heterogeneity of the reconstituted Ca release channels is likely due to the regulatory roles of other junctional SR membrane proteins on the Ca release channel.     

帕里红景天的化学成分研究

从帕里红景天根茎的石油醚和乙醇提取部分共分得１４种结晶性化合物,经光谱分析和化学反应,分别鉴定为二十二醇、二十六酸、十九醇、β－谷甾醇、二十九醇、红景天甙、麦芽糖、棉皮素－８－葡萄糖甙、胡萝卜甙、酪醇、咖啡酸、没食子酸、形花内酯和新化合物帕里甙。     

Escherichia coli alkaline phosphatase: X-ray structural studies of a mutant enzyme (His-412-->Asn) at one of the catalytically important zinc binding sites.

The X-ray structure of a mutant version of Escherichia coli alkaline phosphatase (H412N) in which His-412 was replaced by Asn has been determined at both low (-Zn) and high (+Zn) concentrations of zinc. In the wild-type structure, His-412 is a direct ligand to one of the two catalytically critical zinc atoms (Zn1) in the active site. Characterization of the H412N enzyme in solution revealed that the mutant enzyme required high concentrations of zinc for maximal activity and for high substrate and phosphate affinity (Ma L, Kantrowitz ER, 1994, J Biol Chem 269:31614-31619). The H412N enzyme was also inhibited by Tris, in contrast to the wild-type enzyme, which is activated more than twofold by 1 M Tris. To understand these kinetic properties at the molecular level, the structure of the H412N (+Zn) enzyme was refined to an R-factor of 0.174 at 2.2 A resolution, and the structure of the H412N(-Zn) enzyme was refined to an R-factor of 0.166 at a resolution of 2.6 A. Both indicated that the Asn residue substituted for His-412 did not coordinate well to Zn1. In the H412N(-Zn) structure, the Zn1 site had very low occupancy and the phosphate was shifted by 1.8 A from its position in the wild-type structure. The Mg binding site was also affected by the substitution of Asn for His-412. Both structures of the H412N enzyme also revealed a surface-accessible cavity near the Zn1 site that may serve as a binding site for Tris.(ABSTRACT TRUNCATED AT 250 WORDS)     

喀喇昆仑、昆仑山地区植物元素含量的区域分异和数量分析

对喀喇昆仑、昆仑山地区87种植物21个元素含量及区域分异的研究表明,Ca、Cr、Cd、Fe、V含量比高等植物含量偏高,Ph、P的含量偏低。同种植物在不同地点元素含量有差异。盐柴荒漠植物中Na、K、Mg、P含量较高;高山草甸、冰缘植被植物Ba、Ca、Fe、V、Ti含量较高。各植被类型植物元素含量Na/K差异最大,Ca/Mg较小,Fe/Al差异最小。其变异系数分别为153.5、20.5和15.9.%