Selective separation and enrichment of peptides for MS analysis using the microspheres composed of Fe3O4@nSiO2 core and perpendicularly aligned mesoporous SiO2 shell

In this work, we report the development of a novel enrichment protocol for peptides by using the microspheres composed of Fe₃O₄@nSiO₂ Core and perpendicularly aligned mesoporous SiO₂ shell (designated Fe₃O₄@nSiO₂@mSiO₂). The Fe₃O₄@nSiO₂@mSiO₂ microspheres possess useful magnetic responsivity which makes the process of enrichment fast and convenient. The highly ordered nanoscale pores (2 nm) and high‐surface areas of the microspheres were demonstrated to have good size‐exclusion effect for the adsorption of peptides. An increase of S/N ratio over 100 times could be achieved by using the microspheres to enrich a standard peptide, and the application of the microspheres to enrich universal peptides was performed by using myoglobin tryptic digest solution. The enrichment efficiency of re‐used Fe₃O₄@nSiO₂@mSiO₂ microspheres was also studied. Large‐scale enrichment of endogenous peptides in rat brain extract was achieved by the microspheres. Automated nano‐LC‐ESI‐MS/MS was applied to analyze the sample after enrichment, and 60 unique peptides were identified in total. The facile and low‐cost synthesis as well as the convenient and efficient enrichment process of the novel Fe₃O₄@nSiO₂@mSiO₂ microspheres makes it a promising candidate for selectively isolation and enrichment of endogenous peptides from complex biological samples.     

内蒙古宝格达乌拉晚中新世副竹鼠化石(英文)

描述了1996-2007年间在内蒙古阿巴嘎旗晚中新世宝格达乌拉组采集的副竹鼠化石。材料包括下颌骨1件、牙齿14枚和肢骨4件,分别采自该组的2个地点。根据标本较大的尺寸、形态特征,以及颊齿的釉质曲线高度,宝格达乌拉材料被归入三趾马层副竹鼠Pararhizomys hipparionum Teilhard de Chardin Young,1931。Pararhizomys是一类具高冠、脊形和冠面构造简单颊齿的啮齿动物。该属目前发现的化石地点少,材料也不多,主要集中于中国北方和蒙古高原周缘,其地史分布为晚中新世早期至上新世中期。与鼢鼠类(siphneids)和鼠平类(arvicolids)一样,Pararhizomys属的颊齿有由低冠到高冠发展的趋势,具体表现为牙齿侧面釉质曲线(dentine tract)由平直、远离内外两侧谷底到起伏、接近甚至超过内外两侧谷底。为方便比较,本文为釉质曲线的高度设立"H"指数,即从每侧最深谷的谷底和釉质曲线的最高处取平行于冠面的平行线,此两平行线之间的垂直距离为"H"。H值越大,表明齿冠越低,反之则齿冠越高。尽管目前发现的副竹鼠标本不多,但似乎可以看到从早期到晚期,其颊齿的个体有从小变大,釉质曲线高度H值逐渐减小,即齿冠逐渐增高的趋势。由于Pararhizomys的牙齿形态多少与竹鼠类的低冠竹鼠Brachyrhizomys和竹鼠属Rhizo-mys及拟速掘鼠属Tachyoryctoides有相似之处,故常被与Brachyrhizomys和Rhizomys一起归入竹鼠科(Rhizom yidae),但该属的牙齿不具中脊和下中脊,褶沟少,一般为2-3个,与上述三属有明显的不同。本文对下门齿所作的切片观察也表明,Pararhizomys的釉质层结构与Brachyrhizomys,Rhizomys和Tachyoryctoides者相差甚远,其内层(PI)明显增厚,釉柱和釉柱间质(IPM)的排列方式存在明显差别。颊齿的冠高、冠面形态,以及下门齿的釉质层结构,似乎都表明了Pararhizomys属不大可能归入竹鼠科或速掘鼠科(Tachyorictoididae)。而下门齿釉质层切片显示了Brachyrhizomys与Rhizomys有着高度相似的釉质结构,进一步证明了两者有较接近的亲缘关系。地理分布上,Pararhizomys与Tachyoryctoides属只发现于古北区,伴生的哺乳动物显示了其可能适应偏冷、干旱的草原环境,而Brachyrhizomys和Rhizomys主要局限于东洋区,共生的哺乳动物多能适应温暖、湿润的树林环境。     

The homology and phylogeny of chondrichthyan tooth enameloid

A systematic SEM survey of tooth microstructure in (primarily) fossil taxa spanning chondrichthyan phylogeny demonstrates the presence of a superficial cap of single crystallite enameloid (SCE) on the teeth of several basal elasmobranchs, as well as on the tooth plates of Helodus (a basal holocephalan). This suggests that the epithelial-mesenchymal interactions required for the development of enameloid during odontogenesis are plesiomorphic in chondrichthyans, and most likely in toothed gnathostomes, and provides phylogenetic support for the homology of chondrichthyan and actinopterygian enameloid. Along the neoselachian stem, we see a crownward progression, possibly modulated by heterochrony, from a monolayer of SCE lacking microstructural differentiation to the complex triple-layered tooth enameloid fabric of neoselachians. Finally, the occurrence of fully-differentiated neoselachian enameloid microstructure (including compression-resistant tangle fibered enameloid and bending-resistant parallel fibered enameloid) in Chlamydoselachus anguineus, a basal Squalean with teeth that are functionally "cladodont," is evidence that triple-layered enameloid microstructure was a preadaption to the cutting and gouging function of many neoselachian teeth, and thus may have played an integral role in the Mesozoic radiation of the neoselachian crown group.     

新疆短命植物小拟南芥耐盐性的初步研究

利用种子萌发及石蜡切片等方法对新疆短命植物小拟南芥(Arabidopsis pumila)在盐胁迫下种子的萌发率及植株生长发育的变化进行了研究,结果显示:(1)盐胁迫对小拟南芥种子萌发具有抑制作用,当去除盐分后,部分种子能够重新萌发.(2)盐分影响幼苗的形态及内部结构,低盐(50 mmol/L)时,幼苗基生叶较大且数量增加;叶中栅栏组织细胞大,排列舒展;根中导管数量明显增多,植株生长健壮而旺盛;而较高盐(150 mmol/L)时,叶片变小增厚,色深绿,底部叶变黄白色,叶中栅栏组织细胞窄小,排列紧密;根中导管数急剧下降,植株生长受到明显抑制.(3)盐胁迫对成株期植株的高度、花序轴长、角果数等性状都有显著影响,但在NaCl浓度达500 mmol/L时,植株仍然存活且有一定的结实率,显示此时的耐盐性比萌发期和幼苗期有显著提高.研究表明,小拟南芥从幼苗至成株期耐盐性逐渐增强,该特征与其对自然生存环境的适应相关.     

十大医疗仪器技术

医械工业的许多革新化进展,使得对病人的医护得到许多根本性的改善和提高,要列出其中最重要的十大应用领域和技术,不是件容易的事。美刊MD＆MD根据目前情况,指出对病人医护、临床实践、产品开发以及整个医械工业具有深远影响的十大医疗仪器技术。这些技术以其新产品对人类的医疗保健作出了重大的贡献。     

An Overview of Structural DNA Nanotechnology

Structural DNA Nanotechnology uses unusual DNA motifs to build target shapes and arrangements. These unusual motifs are generated by reciprocal exchange of DNA backbones, leading to branched systems with many strands and multiple helical domains. The motifs may be combined by sticky ended cohesion, involving hydrogen bonding or covalent interactions. Other forms of cohesion involve edge-sharing or paranemic interactions of double helices. A large number of individual species have been developed by this approach, including polyhedral catenanes, a variety of single-stranded knots, and Borromean rings. In addition to these static species, DNA-based nanomechanical devices have been produced that are ultimately targeted to lead to nanorobotics. Many of the key goals of structural DNA nanotechnology entail the use of periodic arrays. A variety of 2D DNA arrays have been produced with tunable features, such as patterns and cavities. DNA molecules have be used successfully in DNA-based computation as molecular representations of Wang tiles, whose self-assembly can be programmed to perform a calculation. About 4 years ago, on the fiftieth anniversary of the double helix, the area appeared to be at the cusp of a truly exciting explosion of applications; this was a correct assessment, and much progress has been made in the intervening period.     

Turbulence and stratification in Priest Pot,a productive pond in a sheltered environment

Priest Pot is an example of the abundant ponds that, collectively, contribute crucially to species diversity. Despite extensive biological study, little has been reported about the physical framework that supports its ecological richness. This article elucidates the physical character of Priest Pot’s water column and thus that of similar water bodies. Vertical thermal microstructure profiles were recorded during summer 2003 and analyzed alongside concurrent meteorological data. During summer stratification, the thermal structure appeared to be dominated by surface heat fluxes. Surface wind stress, limited by sheltering vegetation, caused turbulent overturns once a surface mixed layer was present but appeared to contribute little to setting up the thermal structure. Variations in full-depth mean stratification occurred predominantly over seasonal and ∼5-day time scales, the passage of atmospheric pressure systems being posited as the cause of the latter. In the uppermost ∼0.5 m, where the stratification varied at subdaily time scales, turbulence was active (sensu Ivey and Imberger 1991) when this layer was mixed, with dissipation values ε ∼ 10⁻⁸ m² s⁻³ and vertical diffusivity K_Z = 10⁻⁴ — 10⁻⁶ m² s⁻¹. Where the water column was stratified, turbulence was strongly damped by both buoyancy and viscosity, and K_Z was an order of magnitude smaller. Vertical transport in the mixed layer occurred via many small overturns (Thorpe scale r.m.s. and maximum values were typically 0.02 m and 0.10 m, respectively), and seston were fully mixed through the water column.     

Effective potentials between gold nano crystals – functional dependence on temperature

A method is presented that allows to combine the effective potential between two nano crystals (NC), the potential of mean force (PMF), as obtained from all-atomistic molecular dynamics simulations with perturbation theory. In this way, a functional dependence of the PMF on temperature is derived, which enables the prediction of the PMF in a wide temperature range. We applied the method to systems of capped gold NCs of different size. They show very good agreement with data from atomistic simulations.     

低温胁迫下枇杷幼果种子膜脂过氧化、保护酶活性及显微结构的变化

枇杷(Eriobotrya japonica)开花结果正值冬季低温期,易受低温影响,因此寒害成为抑制枇杷健康生长、发育的重要因素之一。种子作为产生多种内源激素的中心,其健康程度与枇杷果实正常发育息息相关。该研究以四川省成都市龙泉驿区柏合镇的‘早钟六号’枇杷幼果种子为材料,经不同低温(6、3、0、-3℃)胁迫不同时间(12、24、36、48 h)后,对其相对电导率、丙二醛(MDA)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)的变化进行测定以及细胞解剖结构分析,旨在探究枇杷幼果种子抗寒机制,为提高四川地区枇杷抗寒栽培新技术提供理论和实践依据。结果表明:低温胁迫下,枇杷幼果种子相对电导率及MDA含量随着处理温度的降低整体呈上升趋势;保护酶SOD、CAT活性在低温胁迫前期不同程度升高,至某个低温后呈下降趋势;而POD活性总体呈升-降-升趋势;相对电导率、MDA含量、SOD活性、CAT活性、POD活性的变化临界温度均为6℃,胁迫临界时间分别为12、24、48、36 h,而MDA含量变化临界温度为3℃,胁迫临界时间为36 h;显微结构表明枇杷幼果种子6℃低温开始受冻,最先受冻部位为种皮,其次为种胚真叶原始体或真叶,最后到细胞破裂,说明枇杷幼果种子随着处理温度降低,细胞结构受损越严重。综上,枇杷幼果种子受冻临界温度为6℃,受冻临界时间为12 h。