何首乌不同种质花粉形态及进化趋势研究

采用电镜扫描法,对48份何首乌种质的花粉形态进行了观察和分析。结果表明:何首乌花粉形状主要为椭球形,少量为长椭球形和近球形,部分种质花粉形状正处于椭球形向长椭球形进化的阶段;极面观主要为三裂圆形,部分种质的变异为半球状、四边形、凹陷状或平三角形;赤道面观主要为椭圆形,部分种质为三角形或四边形;萌发沟3条,狭长,几达两极,部分种质的1条或2条萌发沟中部或近极端处隆起,2条或3条萌发沟在极端处相交;表面纹饰为穴状,部分种质的穴中出现小孔。研究结果表明,何首乌物种正处于活跃进化阶段且因区域及生境的差异其进化速度不一致,低纬度地区的种质进化程度较高纬度地区的高,其最初的起源中心可能位于高纬度地区,在向低纬度地区迁移过程中其花粉形态发生了不同程度的变异。     

The Myeloid LSECtin Is a DAP12-Coupled Receptor That Is Crucial for Inflammatory Response Induced by Ebola Virus Glycoprotein

Fatal Ebola virus infection is characterized by a systemic inflammatory response similar to septic shock. Ebola glycoprotein (GP) is involved in this process through activating dendritic cells (DCs) and macrophages. However, the mechanism is unclear. Here, we showed that LSECtin (also known as CLEC4G) plays an important role in GP-mediated inflammatory responses in human DCs. Anti-LSECtin mAb engagement induced TNF-α and IL-6 production in DCs, whereas silencing of LSECtin abrogated this effect. Intriguingly, as a pathogen-derived ligand, Ebola GP could trigger TNF-α and IL-6 release by DCs through LSECtin. Mechanistic investigations revealed that LSECtin initiated signaling via association with a 12-kDa DNAX-activating protein (DAP12) and induced Syk activation. Mutation of key tyrosines in the DAP12 immunoreceptor tyrosine-based activation motif abrogated LSECtin-mediated signaling. Furthermore, Syk inhibitors significantly reduced the GP-triggered cytokine production in DCs. Therefore, our results demonstrate that LSECtin is required for the GP-induced inflammatory response, providing new insights into the EBOV-mediated inflammatory response.     

Cloning and characterization of three ketoreductases from soil metagenome for preparing optically active alcohols

Objectives

To discover novel ketoreductases (KRED) from soil metagenome preparation of chiral alcohols.

Results

Three putative KRED were cloned, heterologously expressed in Eschericha coli and characterized based on the sequence analysis of soil metagenome. All the three enzymes (KRED424, KRED432, and KRED433) had maximum activity at 55 °C and pH 7. KRED424 had a broader substrate spectrum compared with the other two. Three prochiral carbonyl compounds were used to evaluate the abilities of enantioselective reductions of the KRED. For N-Boc-3-pyrrolidone, all enzymes produced an (S)-type alcohol in enantiomeric excess (>99 % ee). For ethyl 2-oxo-4-phenylbutyrate, KRED424 showed a higher conversion (91.5 %) and enantioselectivity (S-type, >99 % ee) than KRED432 and KRED433. For ethyl 4-chloroacetoacetate (COBE), both of KRED424 and KRED433 completely converted 20 mM substrate and KRED433 could obtain an (R)-alcohol with 94 % ee.

Conclusions

The three ketoreductases have potential in the preparation of pharmaceuticals and fine chemicals.

     

A genome-wide analysis of sumoylation-related biological processes and functions in human nucleus

Protein sumoylation is an important reversible post-translational modification of proteins in the nucleus, and it orchestrates a variety of the cellular processes. Genome-wide analysis of functional abundance and distribution of Small Ubiquitin-related MOdifier (SUMO) substrates may shed a light on how sumoylation is involved in nuclear biological processes and functions. Two interesting questions about sumoylation have emerged: (1) how many SUMO substrates exist in mammalian proteomes, such as human and mouse, (2) and what are their functions and how are they involved in a variety of biological processes? To address these two questions,we present an in silico genome-scale analysis for SUMO substrates in human. Based on the pattern recognition and phylogenetic conservation, we retrieved a list of 2683 potential SUMO substrates conserved in both human and mouse. Then, by functional enrichment analysis, we surveyed the over-represented GO terms and functional domains of them against the whole human proteome. Besides the consistence between our analyses and in vivo or in vitro work, the in silico predicted candidates also point to several potential roles of sumoylation, e.g., perception of sound. These potential SUMO substrates in human are of great value for further in vivo or in vitro experimental analysis.     

Magnetic catechol-chitosan with bioinspired adhesive surface: preparation and immobilization of ω-transaminase

The magnetic chitosan nanocomposites have been studied intensively and been used practically in various biomedical and biological applications including enzyme immobilization. However, the loading capacity and the remained activity of immobilized enzyme based on existing approaches are not satisfied. Simpler and more effective immobilization strategies are needed. Here we report a simple catechol modified protocol for preparing a novel catechol-chitosan (CCS)-iron oxide nanoparticles (IONPs) composites carrying adhesive moieties with strong surface affinity. The ω-transaminase (ω-TA) was immobilized onto this magnetic composite via nucleophilic reactions between catechol and ω-TA. Under optimal conditions, 87.5% of the available ω-TA was immobilized on the composite, yielding an enzyme loading capacity as high as 681.7 mg/g. Furthermore, the valuation of enzyme activity showed that ω-TA immobilized on CCS-IONPs displayed enhanced pH and thermal stability compared to free enzyme. Importantly, the immobilized ω-TA retained more than 50% of its initial activity after 15 repeated reaction cycles using magnetic separation and 61.5% of its initial activity after storage at 4°C in phosphate buffered saline (PBS) for 15 days. The results suggested that such adhesive magnetic composites may provide an improved platform technology for bio-macromolecules immobilized.     

Effects of plateau pika (Ochotona curzoniae) on alpine meadow phytocoenosium and analysis of the strategy it uses to expand habitat

High-density plateau pikas (Ochotona curzoniae) disturbance is one of the main causes of alpine meadow degradation. The response of phytocoenosium to the disturbance of plateau pika may reflect its habitat expanding strategy. We used quadrat sampling method to investigate vegetation height, coverage, and aboveground biomass of non-pika area (NA), transition area (TA), and pika-active area (AA) distributed continuously in alpine meadow located in Guoluo Tibetan Autonomous County of Qinghai Province in 2011 and 2012. The results showed that, from NA to AA (i) vegetation coverage, height, and above-ground biomass decreased (P < 0.01). (ii) While the number of plant species decreased from 41 to 30, and species diversity decreased significantly (P < 0.05), evenness of the alpine meadow showed no significant variations. (iii) Dominant species changed from grasses to weeds. (iv) While plants in TA showed no obvious difference in height between 2011 and 2012, coverage reduced significantly (P < 0.05). These results demonstrate that (i) plateau pikas disturbance on alpine meadow will change plant community structure and composition, directly leading to degeneration of alpine meadow. Additionally, (ii) plateau pikas expand their habitat by altering plant coverage firstly.