Prospective of Genomics in Revealing Transmission, Reassortment and Evolution of Wildlife-Borne Avian Influenza A (H5N1) Viruses

The outbreak of highly pathogenic avian influenza (HPAI) H5N1 disease has led to significant loss of poultry and wild life and case fatality rates in humans of 60%. Wild birds are natural hosts for all avian influenza virus subtypes and over120 bird species have been reported with evidence of H5N1 infection. Influenza A viruses possess a segmented RNA genome and are characterized by frequently occurring genetic reassortment events, which play a very important role in virus evolution and the spread of novel gene constellations in immunologically naïve human and animal populations. Phylogenetic analysis of whole genome or sub-genomic sequences is a standard means for delineating genetic variation, novel reassortment events, and surveillance to trace the global transmission pathways. In this paper, special emphasis is given to the transmission and circulation of H5N1 among wild life populations, and to the reassortment events that are associated with inter-host transmission of the H5N1 viruses when they infect different hosts, such as birds, pigs and humans. In addition, we review the inter-subtype reassortment of the viral segments encoding inner proteins between the H5N1 viruses and viruses of other subtypes, such as H9N2 and H6N1. Finally, we highlight the usefulness of genomic sequences in molecular epidemiological analysis of HPAI H5N1 and the technical limitations in existing analytical methods that hinder them from playing a greater role in virological research.     

Self-assembled graphene platelet-glucose oxidase nanostructures for glucose biosensing

Graphene platelet-glucose oxidase (GP-GOD) nanostructures have been prepared through self-assembly of GOD and chitosan (CS) functionalized GPs by electrostatic attraction in aqueous solution. The stable aqueous dispersion of GPs was prepared by chemical reduction of graphene oxide with the use of CS as a reducing and stabilizing agent. UV-vis spectroscopy, X-ray diffraction, transmission electron microscopy, scanning electron microscopy and X-ray photoelectron spectroscopy were used to characterize the resulting GPs and GP-GOD nanostructures. Furthermore, a glucose biosensor was constructed by deposition of the resultant GP-GOD on the surface of glassy carbon electrode. It was found that the resulting biosensor exhibits good response to glucose. The linear detection range is estimated to be from 2 to 22 mM (r=0.9987), and the detection limit is estimated to be 20 μM at a signal-to-noise ratio of 3.     

链霉菌ZG0429的分类鉴定与链霉亲和素的分离纯化研究

从土壤中筛选得到1株高产链霉亲和素的放线菌ZG0429,根据形态观察、培养特征、生理生化鉴定以及16S rRNA序列分析,初步判定该菌株为链霉菌属中的淡紫灰链霉菌(Streptomyces lavendulae)。经发酵,ZG0429的链霉亲和素产量可达201.0mg/L。进一步采用硫铵沉淀和凝胶过滤层析纯化,链霉亲和素的回收率为76.87%,纯度可以达到97.03%。该方法简单易行,成本低廉,可得到高产量、高纯度、高活性的目的蛋白,为链霉亲和素发酵产品的大规模纯化提供了依据。     

Crystal structures of GII.10 and GII.12 norovirus protruding domains in complex with histo-blood group antigens reveal details for a potential site of vulnerability

Noroviruses are the dominant cause of outbreaks of gastroenteritis worldwide, and interactions with human histo-blood group antigens (HBGAs) are thought to play a critical role in their entry mechanism. Structures of noroviruses from genogroups GI and GII in complex with HBGAs, however, reveal different modes of interaction. To gain insight into norovirus recognition of HBGAs, we determined crystal structures of norovirus protruding domains from two rarely detected GII genotypes, GII.10 and GII.12, alone and in complex with a panel of HBGAs, and analyzed structure-function implications related to conservation of the HBGA binding pocket. The GII.10- and GII.12-apo structures as well as the previously solved GII.4-apo structure resembled each other more closely than the GI.1-derived structure, and all three GII structures showed similar modes of HBGA recognition. The primary GII norovirus-HBGA interaction involved six hydrogen bonds between a terminal αfucose1-2 of the HBGAs and a dimeric capsid interface, which was composed of elements from two protruding subdomains. Norovirus interactions with other saccharide units of the HBGAs were variable and involved fewer hydrogen bonds. Sequence analysis revealed a site of GII norovirus sequence conservation to reside under the critical αfucose1-2 and to be one of the few patches of conserved residues on the outer virion-capsid surface. The site was smaller than that involved in full HBGA recognition, a consequence of variable recognition of peripheral saccharides. Despite this evasion tactic, the HBGA site of viral vulnerability may provide a viable target for small molecule- and antibody-mediated neutralization of GII norovirus.     

A vertebrate case study of the quality of assemblies derived from next-generation sequences

The unparalleled efficiency of next-generation sequencing (NGS) has prompted widespread adoption, but significant problems remain in the use of NGS data for whole genome assembly. We explore the advantages and disadvantages of chicken genome assemblies generated using a variety of sequencing and assembly methodologies. NGS assemblies are equivalent in some ways to a Sanger-based assembly yet deficient in others. Nonetheless, these assemblies are sufficient for the identification of the majority of genes and can reveal novel sequences when compared to existing assembly references.     

The EGFP/hERG fusion protein alter the electrophysiological properties of hERG channels in HEK293 cells

EGFP (enhanced green fluorescent protein) tagged to either the N (amino)-terminus [EGFP/hERG (human ether-a-go-go-related gene)] or C (carboxyl)-terminus (hERG/EGFP) of hERG channel is used to study mutant channel protein trafficking for several years. However, it has been reported that the process can alter hERG channel properties. The aim of the study was to determine whether EGFP tagged to N-terminus of hERG channels would alter the cellular localizations and the electrophysiological properties of hERG channels compared with untagged hERG channels. The hERG channels tagged with or without EGFP were transiently expressed in HEK (human embryonic kidney) 293 cells using a lipofectamine method. HEK 293 cells expressing pCDNA3-hERG or pEGFP-hERG were double immunolabelled with anti-hERG and anti-calnexin (an ER marker protein) followed with FITC- and TRITC (tetramethylrhodamine β-isothiocyanate)-labelled secondary antibodies, respectively. Confocal laser scanning microscope was used to observe the cellular localization of EGFP-tagged hERG channels and untagged hERG channels. Patch-clamp technique was used to record whole cell currents. We found that the EGFP/hERG fusion protein and untagged hERG channels were both expressed not only on the cell surface membrane but also in the cytoplasm of HEK293 cells. The EGFP/hERG appeared to influence the hERG channel gating properties, including reduction of the peak tail current density, more rapid inactivation process, faster recovery from inactivation and faster deactivation kinetics compared with untagged hERG channels. Our results suggest that the EGFP/hERG channel alter the electrophysiological properties of hERG channel, but it does not seem to alter the cellular location of hERG channels. Thus, EGFP tagging to N-terminus might be used for research of subcellular location of hERG channels but not for the channel electrophysiological properties.     

A biochemically structured model for Saccharomyces cerevisiae.

A biochemically structured model for the aerobic growth of Saccharomyces cerevisiae on glucose and ethanol is presented. The model focuses on the pyruvate and acetaldehyde branch points where overflow metabolism occurs when the growth changes from oxidative to oxido-reductive. The model is designed to describe the onset of aerobic alcoholic fermentation during steady-state as well as under dynamical conditions, by triggering an increase in the glycolytic flux using a key signalling component which is assumed to be closely related to acetaldehyde. An investigation of the modelled process dynamics in a continuous cultivation revealed multiple steady states in a region of dilution rates around the transition between oxidative and oxido-reductive growth. A bifurcation analysis using the two external variables, the dilution rate, D, and the inlet concentration of glucose, S(f), as parameters, showed that a fold bifurcation occurs close to the critical dilution rate resulting in multiple steady-states. The region of dilution rates within which multiple steady states may occur depends strongly on the substrate feed concentration. Consequently a single steady state may prevail at low feed concentrations, whereas multiple steady states may occur over a relatively wide range of dilution rates at higher feed concentrations.     

培养条件对里氏木霉306菌体形态和t-PA生物合成的影响

里氏木霉（Trichoderrna reesei）306是能够生物合成组织型纤溶酶原激活剂（t-PA）的基因工程菌株。在对其液态深层培养时,发现随培养夸件和培养时间的变化,其菌体能以松散和菌丝球的两种形态存在。菌体形态和t-PA的产生密切相关。培养基中无机盐和表面活性剂的种类和添加量以及接种量和pH等培养条件是影响里氏木霉306菌体形态和t-PA合成的主要因素。在液态深层培养过程中,菌体以松散的菌丝体形态生长,形成纸浆状发酵液,利于t-PA的合成。