Tropospheric ozone-induced structural changes in leaf mesophyll cell walls in grapevine plants

The structural changes in leaves of grapevine plants (Vitis vinifera L.) exposed to different ozone concentrations were investigated. Ozone fumigations were performed in open-top chambers at four different ozone levels (charcoal-filtered air (F), ambient air (N), ambient air + 25 mm³m⁻³ ozone (O-25) and ambient air + 50 mm³m⁻³ ozone (O-50)). The leaves of plants from chambers with increased ozone concentrations (O-25 and O-50) were significantly thicker than the controls (F), owing to increased thickness of the mesophyll layer. Observing O-50 leaves, it was found that the mesophyll cell wall displayed structural changes. In some places cell wall thickness increased up to 1 μm. We found callose deposits on the inner side of the cell walls of mesophyll cells. These data are in accord with the concept that the mesophyll cell wall acts as a barrier against the penetration of tropospheric ozone into the cells.     

Metal-ion interactions with carbohydrates. Crystal structure and FT-IR study of the SmCl3-ribose complex

A single-crystal of SmCl₃·C₅H₁₀O₅·5H₂O was obtained from methanol-water solution and its structure determined by X-ray. Two forms of the complex as a pair of anomers and related conformers were found in the single-crystal in a disordered state. One ligand is α-d-ribopyranose in the ⁴C₁ conformation and the other one is β-d-ribopyranose. The anomeric ratio is 1:1. Both ligands provide three hydroxyl groups in ax-eq-ax orientation for coordination. The Sm³⁺ ion is nine-coordinated with five Sm-O bonds from water molecules, three Sm-O bonds from hydroxyl groups of the d-ribopyranose and one Sm-Cl bond. The hydroxyl groups, water molecules and chloride ions form an extensive hydrogen-bond network. The IR spectral C-C, O-H, C-O, and C-O-H vibrations were observed to be shifted in the complex and the IR results are in accord with those of X-ray diffraction.     

Structural diversity of neutral bis-(β-iminoaldehyde) complexes of nickel(II)

Series of Ni^II and Cu^II complexes with dianionic [N₂O₂] ligands were synthesized and characterised applying spectroscopic and X-ray diffraction techniques. The ligands were obtained by 1:2 condensation of ethylene- and propylenediamine with malonic aldehyde derivatives (R² = H, R¹ = H or OCH₃). Although the molecular formulae of the complexes are quite similar, the X-ray investigations have proved a significant structural diversity in the solid state. Among others, we found some simple nearly planar molecules stacked in the crystal lattice with electron density of six-membered rings delocalised over the chelate rings as well as some very complex polymeric or nickel acetate bridged trinuclear complexes. The coordination of the nickel ion by surrounding oxygen and nitrogen atoms is square-planar in the simplest case and octahedral in the most complex one. Small topological differences in similar molecules generate completely different crystal structures.From magnetic studies, a small, negative value of J obtained confirms the occurrence of weak antiferromagnetic interactions between the Ni^II ions in polymeric chain of the propylenediamine dialdehyde substituted derivative.     

Characterization of microsatellite markers for the invasive ant species Anoplolepis gracilipes

We present primer sequences for eight polymorphic microsatellite loci for the formicine ant Anoplolepis gracilipes, a serious pest species in South‐East Asia and Pacific islands and still spreading on all continents. Microsatellite loci were isolated with a highly efficient method of enrichment. The number of alleles ranged from two to 19 with an observed heterozygosity ranging from 0.842 to 1.0. The markers were designed for a sociogenetic study as well as for population genetics.     

Molecular cloning, gene localization, and structure of human cyclin B3

Here we describe the molecular cloning of human cyclin B3, its localization, and its structure. It is localized in the subcentromeric region of the X chromosome, still not completely sequenced by the Human Genome Project. This cyclin B3 is unusually large for a mitotic cyclin. Its mRNAs were found in all tissues and were particularly abundant in testis. At least three splice variants were found in the ORF and three variants in the 5'UTR.     

中国生物多样性核心监测指标遥感产品体系构建与思考

生物多样性的稳定维持关乎人类生存发展与地球健康。生物多样性核心监测指标(Essential Biodiversity Variables, EBVs)旨在结合地面调查与遥感技术, 为大尺度、长时间序列的生物多样性监测提供新的解决方案。然而, 目前学界仍然缺乏一套国家尺度标准化EBVs遥感监测产品数据集, 以进行生物多样性评估。本研究旨在对中国生物多样性核心监测指标遥感产品进行体系构建与思考, 首先综述了目前EBVs的遥感研究概况, 并根据EBVs研究文献的数量进行调研分析; 同时, 本文在已有遥感生物多样性产品优先标准的基础上, 添加了“可重复性”的新标准, 并据此构建了中国EBVs遥感产品体系与监测数据集的指标清单, 最终对中国EBVs遥感研究存在的问题进行思考与讨论。本研究可为中国的生物多样性遥感监测提供科学依据, 有望为中国生物多样性政策的制定提供支撑。     

利用ISSR标记研究野大豆居群内遗传变异及其取样策略

为了有效地保护野大豆(Glycine soja Sieb.et Zucc.)并制定合理的居群取样策略,对上海江湾机场的一个人然野大豆居群进行了 100个单株(个体)的随机取样,并用ISSR分子标记对其进行了遗传多样性分析.利用筛选出的15条ISSR引物在这个居群中检测到较高的遗传变异,样本内个体间的相似系数变化在0.17～0.89之间.居群内平均每个位点的平均预期杂合度(He)为0.171 4,香农指数(I)为0.271 4.PCA分析显示,江湾野大豆居群内的遗传变异不是呈均匀分布,而是呈从状分布.该野大豆居群遗传多样性和样本内个体数量间的相关性分析显示:在个体数少于40的情况下,遗传多样性随个体数的增加而迅速增加;当样本中的个体数大于40时,遗传多样性的增加减慢并很快趋于饱和.研究表明:对野大豆居群进行异地保护时,对各居群的采样植株数不应当低于35～45;在居群内采样时,所采集的个体之间最好相隔一定的空间距离.     

pH-dependent amyloid and protofibril formation by the ABri peptide of familial British dementia

The ABri is a 34 residue peptide that is the major component of amyloid deposits in familial British dementia. In the amyloid deposits, the ABri peptide adopts aggregated beta-pleated sheet structures, similar to those formed by the Abeta peptide of Alzheimer's disease and other amyloid forming proteins. As a first step toward elucidating the molecular mechanisms of the beta-amyloidosis, we explored the ability of the environmental variables (pH and peptide concentration) to promote beta-sheet fibril structures for synthetic ABri peptides. The secondary structures and fibril morphology were characterized in parallel using circular dichroism, atomic force microscopy, negative stain electron microscopy, Congo red, and thioflavin-T fluorescence spectroscopic techniques. As seen with other amyloid proteins, the ABri fibrils had characteristic binding with Congo red and thioflavin-T, and the relative amounts of beta-sheet and amyloid fibril-like structures are influenced strongly by pH. In the acidic pH range 3.1-4.3, the ABri peptide adopts almost exclusively random structure and a predominantly monomeric aggregation state, on the basis of analytical ultracentrifugation measurements. At neutral pH, 7.1-7.3, the ABri peptide had limited solubility and produced spherical and amorphous aggregates with predominantly beta-sheet secondary structure, whereas at slightly acidic pH, 4.9, spherical aggregates, intermediate-sized protofibrils, and larger-sized mature amyloid fibrils were detected by atomic force microscopy. With aging at pH 4.9, the protofibrils underwent further association and eventually formed mature fibrils. The presence of small amounts of aggregated peptide material or seeds encourage fibril formation at neutral pH, suggesting that generation of such seeds in vivo could promote amyloid formation. At slightly basic pH, 9.0, scrambling of the Cys5-Cys22 disulfide bond occurred, which could lead to the formation of covalently linked aggregates. The presence of the protofibrils and the enhanced aggregation at slightly acidic pH is consistent with the behavior of other amyloid-forming proteins, which supports the premise that a common mechanism may be involved in protein misfolding and beta-amyloidosis.     

Impact of deglycosylation and thermal stress on conformational stability of a full length murine igG2a monoclonal antibody: Observations from molecular dynamics simulations

With the rise of antibody based therapeutics as successful medicines, there is an emerging need to understand the fundamental antibody conformational dynamics and its implications towards stability of these medicines. Both deglycosylation and thermal stress have been shown to cause conformational destabilization and aggregation in monoclonal antibodies. Here, we study instabilities caused by deglycosylation and by elevated temperature (400 K) by performing molecular dynamic simulations on a full length murine IgG2a mAb whose crystal structure is available in the Protein Data bank. C^α‐atom root mean square deviation and backbone root mean square fluctuation calculations show that deglycosylation perturbs quaternary and tertiary structures in the C_H2 domains. In contrast, thermal stress pervades throughout the antibody structure and both Fabs and Fc regions are destabilized. The thermal stress applied in this study was not sufficient to cause large scale unfolding within the simulation time and most amino acid residues showed similar average solvent accessible surface area and secondary structural conformations in all trajectories. C_H3 domains were the most successful at resisting the conformational destabilization. The simulations helped identify aggregation prone regions, which may initiate cross‐β motif formation upon deglycosylation and upon applying thermal stress. Deglycosylation leads to increased backbone fluctuations and solvent exposure of a highly conserved APR located in the edge β‐strand A of the C_H2 domains. Aggregation upon thermal stress is most likely initiated by two APRs that overlap with the complementarity determining regions. This study has important implications for rational design of antibody based therapeutics that are resistant towards aggregation. Proteins 2013. © 2012 Wiley Periodicals, Inc.