糖酵解模型在H~k空间中全局吸引子存在性（英文）

本文用迭代程序、线性算子半群的正则性估计以及推广的全局吸引子的存在性定理,证明了糖酵解模型在H~k空间(对任意k≥0)中存在一个全局吸引子,并且在H~k范数下吸引H~k(Ω)空间中任何有界集.     

脉冲微分方程正周期解的存在唯一性与全局吸引性（英文）

本文,我们考虑了脉冲微分方程.正周期解的存在唯一性与全局吸引性,通过使用不动点定理,建立了该方程唯一正周期解的存在性与全局吸引性的充分条件.特别地,我们给出x是其他正解的全局吸引子.我们的结果推广和改进了已有文献结果.     

双营养Chemostat模型周期解的全局吸引性

研究含有时滞的双营养单种群Ｃｈｅｍｏｓｔａｔ模型周期解的全局吸引性,首先利用强正、凹算子理论给出了系统存在唯一正周期解的充分条件,然后利用泛函微分方程的单调理论得到了正周期解的全局吸引性。     

胡萝卜（DaucuscarotaL.）胚性细胞蛋白的分离研究

应用ＩＥＦ／ＳＤＳ－ＰＡＧＥ双向电泳技术,比较了胡萝卜胚性细胞、非胚性细胞和不同发育时期的胚状体中可溶性蛋白的双向电泳图谱,结果发现在胚性细胞中特异存在的胚性细胞蛋白在不同发育时期的胚状体中也存在,但在非胚性细胞中不存在。因此,ＥＣＰ４５－１和４５－２可能属于同一因基家族。     

两性吸引除了性信息素还有其他因素

声音，色彩和气味是同种昆虫间性吸引的重要因素。对于这些种特异的性吸引因素，尤其是性信息素的作用，法国的科学家在2007年6月19日《PLoS One》上发表文章，提出质疑。他们利用性信息存在差异的Z型和E型欧洲玉米螟Ostrinia　nubilalis进行杂交和回交，获得了与亲本性信息素相同但是遗传背景不同和与亲本性信息素不同但是遗传背景相似的个体。     

治疗性克隆研究进展

核移植来源的胚胎干细胞 (ES) 细胞在动物疾病模型上的成功治疗作用以及核移植来源的患者特异的ES细胞研究进展有望将这一技术即治疗性克隆应用于人类疾病治疗.本文对治疗性克隆的研究进展、治疗性克隆研究中存在的问题以及治疗性克隆的应用前景作一综述和讨论.     

植物的编程性细胞死亡

植物细胞在一定的生理或病理条件下,遵循自身的程序,自己结束生命。新近遗传学、生物化学及形态学证据表明,植物细胞的这种死亡是一个主动的过程,称之为编程性细胞死亡。文章综述了植物体中存在的编程性细胞死亡现象及其调控机理。     

n种群Lotka-Volterra周期系数捕食-竞争系统周期解的存在性与全局吸引性

在本文中,作者考察了n种群Lotak-Volterra周期捕食-竟争系统,用比较定理、Brouwer不定点定理和V函数方法证明了正解的最终有界性、正周期解的存在性、正周期解的全局吸引性及唯一性．     

胡萝卜(Daucus carota L.)胚性细胞蛋白的分离研究

应用IEF/SDS-PAGE双向电泳技术,比较了胡萝卜胚性细胞、非胚性细胞和不同发育时期的胚状体中可溶性蛋白的双向电泳图谱,结果发现在胚性细胞中特异存在的胚性细胞蛋白在不同发育时期的胚状体中也存在,但在非胚性细胞中不存在。因此,推测体细胞胚胎发生所需的一些基因在胚性细胞中就早已表达了。我们还成功地分离和测定了ECP 45-2 N-末端和中央部分氨基酸序列。与已知氨基酸序列相比,ECP 45-2部分氨基酸序列与ECP 45-1 部分氨基酸序列具有较高比例的同源性。因此, ECP 45-1和45-2可能属于同一因基家族。     

胶质细胞源性神经营养因子受体

胶质细胞源性神经营养因子能够促进多种神经细胞特别是多巴胺能神经元及运动神经元存活。胶质细胞源性神经营养因子的信号传递受体是ＲＥＴ受体酪氨酸激酶,受体α亚基是它与ＲＥＴ相互作用的媒介。胶质细胞源性神经营养因子生物学活性的发挥需要ＲＥＴ与受体α亚基同时存在。     

蓝尾石龙子精子的超微结构

蓝尾石龙子(Eumeces elegans)附睾以2．5％戊二醛和1％锇酸双重固定,按常规制作超薄切片,用H-600透射电镜研究观察精子的超微结构。精子由头部和尾组成,头部由顶体复合体和核组成,尾由颈段、中段、主段和末段组成。头部的顶体囊前部扁平,分为皮质和髓质,顶体下锥由类结晶状的顶体下物质组成,穿孔器顶端尖,、穿孔器基板塞子状,细胞核延长,核内小管缺,核伸展部前端具一电子透明区,核肩圆,核陷窝锥形。颈段具片层结构,近端中心粒和远端中心粒的长轴呈直角,9束外周致密纤维与远端中心粒相应的9束三联微管相联,向后与轴丝相应的9束双联微管相联,中央纤维与2个中央单微管相联。中段短,含有线状嵴的柱状线粒体,由连续的规则小卵状或小梯形致密体组成线粒体间的环状结构,纤维鞘伸入中段,终环紧贴于细胞膜的内表面。线粒体与环状结构的模式为：rs1／mi1,rs2／mi2,rs3／mi3,rs4／mi4,横切面上每圈线粒体数目为10个。主段前面部分具薄的细胞质颗粒区。纤维3和8至主段前端消失。轴丝复合体呈“9 2”型。蓝尾石龙子精子超微结构与已描述的石龙子科种类比较发现,与蜓蜥群和胎生群的石龙子相似;但没有发现石龙子科精子的独征。     

Behavioural mode of action of deet: inhibition of lactic acid attraction

Using the mosquito Aedes aegypti in a novel olfactometer that measures movement towards and away from a stimulus, we could not confirm that 'deet' is a repellent of mosquitoes. In the absence of a host, deet was an attractant and in the presence of a host, it was an inhibitor of attraction. This inhibition occurred in the gaseous phase and was therefore not the result of the physical properties of deet. We determined that L-lactic acid, a component of human sweat that is an attractant to mosquitoes, is the target of this inhibition, implying that lactic acid may be a bottleneck in the behavioural cascade preceding blood-sucking.     

1590名农村中老年人生存质量调查分析(英文)

目的:采用SF-36量表中文版评价农村中老年人生存质量,并为提高农村中老年人的生存质量和健康水平提供科学依据和建议。方法:采用随机抽样的方法,采用面对面访谈的形式,记分方法参照国际生存质量评价计划(IQOLA)的制定标准,评价其生理和心理健康状况。结果:1590名农村中老年人男性生存质量得分高于女性。经济水平对农村中老年人的生理健康的影响大于对其心理健康的影响。配偶健在的农村中老年人的各维度得分均高于无配偶者。农村中老年人的各维度得分随教育水平的升高呈升高趋势。结论:农村中老年人的生存质量与年龄成负相关,同时也受文化程度和经济水平等多个因素的影响。因而,对农村中老年人这一弱势群体应该给予更多关注。     

Biosynthesis of pulmonary glycoconjugates. Mechanism of glucosylation of protein and lipid acceptors

In sheep lung microsomes, we have shown that glucosyl-transferases catalize the transfer of glucose from UDP-glucose into four different acceptors. The glucosylated products obtained are as follows: - a glucosyl-phosphoryl-polyprenol (product A) extractable by chloroform/methanol (2:1 by volume). - a product B extractable by chloroform/methanol/water (10:10:3 by volume). The product B was a mixture of five glycolipids, one of them having a chromatographic behaviour similar to the behaviour of a tetrahexosylceramide (asia-lo-GM1). - a product C insoluble in water and organic solvents which has been demonstrated to be a glycoproteinic compound. The molecular weight of this product C was 160 000 as estimated by gel-filtration. The carbohydrate moiety is composed of small oligosaccharides which are found to be attached by O-glycosidic bond to the protein chain. This linkage is not a collagen-like bond.     

Characterization of the translocon of the outer envelope of chloroplasts

The protein translocon of the outer envelope of chloroplasts (Toc) consists of the core subunits Toc159, Toc75, and Toc34. To investigate the molecular structure, the core complex was purified. This core complex has an apparent molecular mass of approximately 500 kD and a molecular stoichiometry of 1:4:4-5 between Toc159, Toc75, and Toc34. The isolated translocon recognizes both transit sequences and precursor proteins in a GTP-dependent manner, suggesting its functional integrity. The complex is embedded by the lipids phosphatidylcholine and digalactosyldiacylglyceride. Two-dimensional structural analysis by EM revealed roughly circular particles consistent with the formation of a stable core complex. The particles show a diameter of approximately 130 A with a solid ring and a less dense interior structure. A three-dimensional map obtained by random conical tilt reconstruction of electron micrographs suggests that a "finger"-like central region separates four curved translocation channels within one complex.     

The effects of glutamine of the maintenance of embryogenic cultures of Cryptomeria japonica

Summary Embryogenic tissues of sugi (Cryptomeria japonica) were induced on a modified Campbell and Durzan (CD) medium containing 1 μM 2,4-dichlorophenoxyacetic acid (2,4-D) and 600 mg l⁻¹ glutamine, and subcultured in the medium of the same composition for over 1 yr. This resulted in a mixed culture of embryogenic and non-embryogenic cells. When embryogenic cells were isolated and cultured independently, their capacity to form embryogenic aggregates was lost. Thus, the non-embryogenic cells present within a mixed culture system were essential to the formation of embryogenic aggregates. When embryogenic tissues were isolated and cultured independently on a high glutamine-containing (2400 mg l⁻¹) medium, dry weights and endogenous levels of glutamine increased, and the tissue could generate a large number of embryogenic aggregates. Amino acid analysis of embryogenic and non-embryogenic cells from the maintenance culture indicated a higher level of glutamine was present in the latter. The high endogenous level of glutamine in the non-embryogenic portion of mixed cell masses may be the supplier of glutamine for maintaining the embryogenic property of the tissues.     

Cause of Senescence of Nine Sorts of Flowers

The levels of endogenous phytohormones and respiratory rate in nine sorts of flowers such as Cymbidium faberi Rolfe, Nopalxochia ackermannii Kunth and others were investigated both at full bloom and senescence and meanwhile the effect of exogenous phytohormones on prolonging the blossoms and promoting ethylene production were tested. There is a high content of endogenous ethylene in all the long-lived flowere, about 3–16 folds higer than the short-lived ones. There is a high level of ABA at full blooming flowers of short-lived flowers, in which there is no or only some cytokinins in it, but the ratio of CTK (6BA+zeatin)/ABA is smaller(l.7). The endogenous ABA reached a much higher level at senescence in all nine sorts of flowers, so it is reasonable to consider that it is ABA which plays an important role of regulation in controlling flower's senescence. There is a much higher level of GA3 and zeatin in the long-lived flowers which is not demonstrated in the shortlived ones. The respiratory rate is one of the factors controtling the longevity of flowers, but it does not play a decided role. Application of 6BA and zeatin prolongs distinctly orchid’s longevity, however exogenous IAA through the promotive action on ethylene production, evidently extends the longevity of the flowers of the Nopalxochia ackermannii Kunth.     

Principles of viable preservation of parasitic Protozoa

Viable preservation is fundamentally different from serial passage as a way of maintaining Protozoa in the laboratory. In serial passage there is continuous selection of a reproducing population so that biological characteristics deviate from those representative of the original population towards those of a population adapted to the special conditions of the passage. Viable preservation arrests reproduction and so, this selection. Viably preserved material, therefore, deserves to be defined by a special term, ‘stabilate’, a stabilate being defined as a population of organisms viably preserved on a unique occasion. Materials maintained by serial passage are appropriately called ‘strains’.     

Asymptotic rates of growth of the extinction probability of a mutant gene

We prove that a result of Haldane (1927) that relates the asymptotic behaviour of the extinction probability of a slightly supercritical Poisson branching process to the mean number of offspring is true for a general Bienaymé-Galton-Watson branching process, provided that the second derivatives of the probability-generating functions converge uniformly to a non-zero limit. We show also by examples that such a result is true more widely than our proof suggests and exhibit some counter-examples.Research supported by NSERC     

Kinetics of littorine content in various developing stages of regenerates of Atropa belladonna

 Aseptically propagated regenerates were cultivated in a hydroponic apparatus, a phytotron or in the field, and their growth and littorine contents were investigated. No littorine was detected in aseptic regenerates cultured on solidified Murashige and Skoog medium, nor was it found in leaves under the three conditions tested. In roots, it was common features to all three conditions tested that littorine increased dramatically after transplantation from culture tubes and was a major alkaloid up to week 4; subsequently the littorine contents varied depending on the cultivation conditions. Roots cultivated in the field showed a marked thickening and rapid disappearance of littorine; those cultivated in the hydroponic apparatus were thin and maintained a high level of littorine for a long time. In a plant cultivated for 16 weeks in a pot, littorine content in the roots decreased with increasing root diameter. Received: 1 October 1999 / Revision received: 16 March 2000 / Accepted: 24 March 2000