植物基因分离技术的发展

1953年Watson和Crick发现DNA双螺旋结构,标志着对生物遗传物质一基因的研究进入了微观的水平。植物基因分离一直是当今生物技术研究的热点,分离植物的功能基因便于对基因的结构和表达进行研究,并可以经转基因技术对已有植物的某些性状进行改良,使其满足人们的要求,从而造福于人类。     

植物基因能使木材更挺直、小麦更高产

科学家在对植物基因的研究中有了两个新的重要发现。这两个新发现表明,充分了解植物基因的功能并合理利用这些基因,能使植物更健康地生长,农业生产更环保,经济收益也更好。     

脉冲热管温度时间序列的非线性混沌分析

运用功率谱分析、自相关分析、关联维数和K熵、R/S分析等线性和非线性分析技术对以FC-72和水为工质的脉冲热管温度波动信号进行了定性和定量研究．研究表明：波动信号具有确定性混沌特性，其重构的动力学系统具有非整数值的关联维，范围在2.5~11之间，K熵为有限正值。Hurst指数在0.8~1之间，表明温度波动信号有强烈的长程相关性。传热特性和关联维之间有密切的联系，热阻越小时关联维数越大。     

超积累植物修复土壤重金属污染的富集机理的研究与进展

植物修复是整治土壤重金属污染的重要手段之一,是目前世界范围内的研究热点,也是目前不多见的土壤污染治理的环境友好技术,而超积累植物是这一技术的关键~([1])。本文就目前超积累植物的特征、富集机理的研究现状进行了介绍。植物超富集重金属机理主要涉及植物对金属离子高的吸收、运输能力,区域化作用及螯合作用等方面,其中跨膜运载蛋白的表达、调控对重金属超富集这一特性起了关键作用。金属阳离子运载蛋白家族在超富集植物中已克隆出多个家族的金属运载蛋白基因,这些基因的过量表达对重金属在细胞中的运输、分布和富集及提高植物的抗性方面发挥了重要作用。     

简讯

上海植物基因研究中心揭牌 上海植物基因研究中心于8月12日揭牌。上海植物基因研究中心是在市政府领导、市科委的协调下,由中科院上海植物生理研究所、复旦大学、上海交通大学、中科院国家基因研究中心和上海市农科院等5大研究单位参与组建的,旨在实现上海在转基因植物的研究与开发方面赶超世界先进水平。上海植物基因研究中心将围绕转基因农作物新品种选育、在重     

肘杆合模机构弹性变形关联特性的研究（上）

研究了注塑机肘杆合模机构系统与机构内零件两者之间弹性变形量的关联特性,研究了拉杆与肘杆两者之间弹性变形量的关联特性,论证了弹性变形与机构运行性能之间的关系,分析了机构刚度之间的关联特征,提出了肘杆机构、拉杆直径、肘杆载面、模板绕度值等弹性变形量关联的设计理论依据、设计准则和设计方法,并举例说明了设计准则及应用效果。     

注塑机肘杆合模机构弹性变形关联特性的研究

研究了注塑机肘杆合模机构系统与机构内零件两者之间弹性变形量的关联特性,研究了拉杆与肘杆两者之间弹性变形量的关联特性,论证了弹性变形与机构运行性能之间的关系,分析了机构刚度之间的关联特征,提出了肘杆机构、拉杆直径、肘杆载面、模板绕度值等弹性变形量关联的设计理论依据、设计准则和设计方法,并举例说明了设计准则及应用效果。     

注塑机肘杆合模机构弹性变形关联特性的研究（下）

研究了注塑机肘杆合模机构系统与机构内零件两者之间弹性变形量的关联特性,研究了拉杆与肘杆两者之间弹性变形量的关联特性,论证了弹性变形与机构运行性能之间的关系,分析了机构刚度之间的关联特征,提出了肘杆机构、拉杆直径、肘杆载面、模板绕度值等弹性变形量关联的设计理论依据、设计准则和设计方法,并举例说明了设计准则及应用效果。     

注塑机肘杆合模机构弹性变形关联特性的研究

研究了注塑机肘杆合模机构系统与机构内零件两者之间弹性变形量的关联特性,研究了拉杆与肘杆两者之间弹性变形量的关联特性,论证了弹性变形与机构运行性能之间的关系,分析了机构刚度之间的关联特征,提出了肘杆机构、拉杆直径、肘杆载面、模板绕度值等弹性变形量关联的设计理论依据、设计准则和设计方法,并举例说明了设计准则及应用效果。     

应用雪花莲凝集素防治害虫的研究进展

虫害是农业生产中的一大难题 ,随着对大量使用化学农药造成的环境问题的关注增强 ,促使更多的研究朝着对环境友好的害虫综合防治策略发展[1] 。抗虫植物基因工程为防治农业害虫提供了新的思路和途径。近年来分离出的大量的抗虫基因 ,包括苏云金芽孢杆菌Bacillusthuringiensis(Bt)内毒素蛋白基因 ,蛋白酶抑制剂ProteinaseInhibitor(PI)基因 ,淀粉酶抑制剂AmylaseInhibitor(AI)基因和植物源凝集素lectin基因 ,已经被转移到许多作物中 ,致力于对一些重要害虫的控制[2 ] 。雪花莲凝集素(Galanthusnivalisagglutinin ,GNA)是植物外源凝集素…     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.