Variation and Evolution in the Karyotype of Lycoris (Amaryllidaceae) V. Chromosomal Variation in L. sanguinea Maxim.

Abstract In 554 bulbs from 38 populations of Lycoris sanguinea , several chromosomal variations have been discovered. Most of the bulbs have a common karyotype consisting of 22 acrocentric ( A ) chromosomes. Though their frequencies are low, some rearranged chromosomes which are aberrant have been found. The aberrants are as follows: 1. Subtelocentrics ( ST ); 2. Telocentrics ( T' ); 3. Metacentrics ( M' ); 4. Very small acrocentrics (a); 5. Very small metacentrics (m); 6. Acentric fragments ( Ac ); and 7. Dicentrics ( Di ) chromosome. All can be easily suspected to be derived from A s. Some aberrations of the satellite chromosomes have been observed also. In addition, a new karyotype composed of 2n=32=31 A + 1 M' chromosomes has been found.     

Structural Identification of Individual Helical Amyloid Filaments by Integration of Cryo-Electron Microscopy-Derived Maps in Comparative Morphometric Atomic Force Microscopy Image Analysis

The presence of amyloid fibrils is a hallmark of more than 50 human disorders, including neurodegenerative diseases and systemic amyloidoses. A key unresolved challenge in understanding the involvement of amyloid in disease is to explain the relationship between individual structural polymorphs of amyloid fibrils, in potentially mixed populations, and the specific pathologies with which they are associated. Although cryo-electron microscopy (cryo-EM) and solid-state nuclear magnetic resonance (ssNMR) spectroscopy methods have been successfully employed in recent years to determine the structures of amyloid fibrils with high resolution detail, they rely on ensemble averaging of fibril structures in the entire sample or significant subpopulations. Here, we report a method for structural identification of individual fibril structures imaged by atomic force microscopy (AFM) by integration of high-resolution maps of amyloid fibrils determined by cryo-EM in comparative AFM image analysis. This approach was demonstrated using the hitherto structurally unresolved amyloid fibrils formed in vitro from a fragment of tau (297–391), termed ‘dGAE’. Our approach established unequivocally that dGAE amyloid fibrils bear no structural relationship to heparin-induced tau fibrils formed in vitro. Furthermore, our comparative analysis resulted in the prediction that dGAE fibrils are structurally closely related to the paired helical filaments (PHFs) isolated from Alzheimer’s disease (AD) brain tissue characterised by cryo-EM. These results show the utility of individual particle structural analysis using AFM, provide a workflow of how cryo-EM data can be incorporated into AFM image analysis and facilitate an integrated structural analysis of amyloid polymorphism.     

长白落叶松转录因子LobHLH34克隆及表达分析

为了解转录因子bHLH在长白落叶松（Larix olgensis）中的功能,探究该基因在长白落叶松不同组织中及不同逆境胁迫下的表达特性,从长白落叶松根、茎和叶3个不同部位的转录组数据中获得bHLH34基因全长序列,并设计引物,克隆得到长白落叶松bHLH34基因,其完整的开放阅读框（ORF）长度为696 bp,共编码231个氨基酸。构建亚细胞定位表达载体,瞬时转化毛果杨（Populus trichocarpa）原生质体,在激光共聚焦显微镜下观察显示,LobHLH34基因定位在细胞核内。系统进化树分析结果显示,长白落叶松与云杉（Picea asperata）、卷柏（Selaginella tamariscina）树种该基因的亲缘关系较近。利用qRT-PCR技术分析了bHLH34基因在长白落叶松中的组织表达特异性和应对非生物胁迫的表达。结果表明LobHLH34基因在长白落叶松的根、茎、叶中均有表达,其中在茎部表达量最低,在叶中相对表达量最高。LobHLH34基因在NaCl、PEG和ABA处理时,不同器官中的表达量也有所不同。推测长白落叶松bHLH34基因参与了植物的生长、发育、响应逆境胁迫的过程,且在不同器官中具有特异性。     

人肝细胞癌预后不良相关基因的生物信息学分析及其临床意义

目的:筛选肝细胞癌(HCC)预后不良相关基因,并探讨其临床意义。方法:在基因表达综合数据库(GEO)中获取符合分析条件的肝细胞癌全基因组表达谱数据并分析得到差异表达基因(DEGs),再运用生物学信息注释及可视化数据库 (DAVID) 和蛋白相互作用数据库 (String) 分别进行功能富集分析和蛋白质互作用网络的构建。利用癌症基因组图谱数据库(TCGA)和Cox比例风险回归模型对相关差异基因进行预后分析。结果:找到一个符合条件的人类HCC数据库 (GSE84402),共筛选出1141个差异表达基因(DEGs),其中上调基因720个,下调基因421个。基因功能富集分析和蛋白质互作用分析结果显示CDK1、CDC6、CCNA2、CHEK1、CENPE 、PIK3R1、RACGAP1、BIRC5、KIF11和CYP2B6为HCC预后的关键基因。TCGA数据库和Cox回归模型分析显示CDC6、PIK3R1、RACGAP1和KIF11的表达升高,CENPE的表达降低与HCC预后不良密切相关。结论:CDC6、CENPE、PIK3R1、RACGAP1和KIF11可能和HCC的预后不良相关,可作为未来HCC预后研究的参考标志物。     

物种多样性和系统发育多样性对阔叶红松林生产力的影响

生物多样性与生态系统功能间的关系已成为生态学研究的热点问题之一,其中植物多样性对森林生产力的驱动作用受到广泛关注,而其潜在驱动机制还存在很大争议.本研究依托黑龙江凉水国家级自然保护区典型阔叶红松林9 hm^2森林动态监测样地,利用2005年和2015年的调查数据,采用线性回归和结构方程模型探究不同空间尺度下物种多样性和系统发育多样性对森林生产力的影响.结果表明:物种多样性和系统发育多样性与生产力均呈正相关,随着空间尺度的增大,物种多样性对生产力的作用强度逐渐增强,而系统发育多样性对生产力的作用逐渐减弱;小尺度下系统发育多样性对生产力的影响大于物种多样性.生产力还受到非生物因素影响,在不同尺度下土壤因子与生产力均呈显著正相关,并且随着尺度的增大,土壤因子对生产力的作用逐渐占据主导地位.在今后研究中应将进化信息与生态系统功能相联系,可为其他多样性度量提供额外的解释力,同时还应考虑空间尺度及非生物因素的影响,为深入了解森林生产力的驱动机制提供科学依据.     

The Small β-Barrel Domain: A Survey-Based Structural Analysis

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Bayesian Weighing of Electron Cryo-Microscopy Data for Integrative Structural Modeling

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Insight into the Structure of the “Unstructured” Tau Protein

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Putative structural rearrangements associated with the interaction of macrocyclic inhibitors with norovirus 3CL protease

Human noroviruses are the primary cause of outbreaks of acute gastroenteritis worldwide. The problem is further compounded by the current lack of norovirus-specific antivirals or vaccines. Noroviruses have a single-stranded, positive sense 7 to 8 kb RNA genome which encodes a polyprotein precursor that is processed by a virus-encoded 3C-like cysteine protease (NV 3CLpro) to generate at least six mature nonstructural proteins. Processing of the polyprotein is essential for virus replication, consequently, NV 3CLpro has emerged as an attractive target for the discovery of norovirus therapeutics and prophylactics. We have recently described the structure-based design of macrocyclic transition state inhibitors of NV 3CLpro. In order to gain insight and understanding into the interaction of macrocyclic inhibitors with the enzyme, as well as probe the effect of ring size on pharmacological activity and cellular permeability, additional macrocyclic inhibitors were synthesized and high resolution cocrystal structures determined. The results of our studies tentatively suggest that the macrocyclic scaffold may hamper optimal binding to the active site by impeding concerted cross-talk between the S₂ and S₄ subsites.