不同林龄胡杨克隆繁殖根系分布特征及其构型

以中龄林和成熟林胡杨为研究对象,采用挖剖面和根窗的方法,研究胡杨繁殖根系分布、根系构型,以及胡杨根蘖与繁殖根系构型之间的关系。结果表明:(1)细根(d<2 mm)的根长密度、根表面积密度,随深度增加呈现指数函数分布;(2)中龄林细根的根长密度、根表面积密度在0—90 cm各层都是显著大于成熟林的对应指标(P<0.05),成熟林的中等粗根(5 mm0.05),且两种林龄的一级侧根数、分枝角度亦无显著差异(P>0.05);(5)对比两种林龄不同根序上的根蘖芽发现,二级根上不定芽个数均是同组一级根上不定芽个数的3—4倍;基于以上对胡杨根系的功能权衡的分析,得出:细根对胡杨根系构型有重要的影响,在胡杨根系功能权衡中扮演重要角色。     

Newly discovered insect RNA viruses in China

Insects are a group of arthropods and the largest group of animals on Earth,with over one million species described to date.Like other life forms,insects suffer from viruses that cause disease and death.Viruses that are pathogenic to beneficial insects cause dramatic economic losses on agriculture.In contrast,viruses that are pathogenic to insect pests can be exploited as attractive biological control agents.All of these factors have led to an explosion in the amount of research into insect viruses in recent years,generating impressive quantities of information on the molecular and cellular biology of these viruses.Due to the wide variety of insect viruses,a better understanding of these viruses will expand our overall knowledge of their virology.Here,we review studies of several newly discovered RNA insect viruses in China.     

In situ hydrogen utilization for high fraction acetate production in mixed culture hollow-fiber membrane biofilm reactor

Syngas fermentation is a promising route for resource recovery. Acetate is an important industrial chemical product and also an attractive precursor for liquid biofuels production. This study demonstrated high fraction acetate production from syngas (H₂ and CO₂) in a hollow-fiber membrane biofilm reactor, in which the hydrogen utilizing efficiency reached 100 % during the operational period. The maximum concentration of acetate in batch mode was 12.5 g/L, while the acetate concentration in continuous mode with a hydraulic retention time of 9 days was 3.6?±?0.1 g/L. Since butyrate concentration was rather low and below 0.1 g/L, the acetate fraction was higher than 99 % in both batch and continuous modes. Microbial community analysis showed that the biofilm was dominated by Clostridium spp., such as Clostridium ljungdahlii and Clostridium drakei, the percentage of which was 70.5 %. This study demonstrates a potential technology for the in situ utilization of syngas and valuable chemical production.     

Discover natural compounds as potential phosphodiesterase-4B inhibitors via computational approaches

cAMP, intracellular cyclic adenosine monophosphate, is a ubiquitous second messenger that plays a key role in many physiological processes. PDE4B which can reduce the cAMP level by hydrolyzing cAMP to 5′-AMP has become a therapeutic target for the treatment of human diseases such as respiratory disorders, inflammation diseases, neurological and psychiatric disorders. However, the use of currently available PDE4B inhibitors is restricted due to serious side effects caused by targeting PDE4D. Hence, we are attempting to find out subfamily-selective PDE4B inhibitors from natural products, using computer-aided approaches such as virtual screening, docking, and molecular dynamics simulation. Finally, four potential PDE4B-selective inhibitors (ZINC67912770, ZINC67912780, ZINC72320169, and ZINC28882432) were found. Compared to the reference drug (roflumilast), they scored better during the virtual screening process. Binding free energy for them was ?317.51, ?239.44, ?215.52, and ?165.77 kJ/mol, better than ?129.05 kJ/mol of roflumilast. The pharmacophore model of the four candidate inhibitors comprised six features, including one hydrogen bond donor, four hydrogen bond acceptors, and one aromatic ring feature. It is expected that our study will pave the way for the design of potent PDE4B-selective inhibitors of new drugs to treat a wide variety of diseases such as asthma, COPD, psoriasis, depression, etc.     

Process of simultaneous hydrogen sulfide removal from biogas and nitrogen removal from swine wastewater

The feasibility of a new flowchart describing simultaneous hydrogen sulfide removal from biogas and nitrogen removal from wastewater was investigated. It took 30 days for the reactor inoculated with aerobic sludge to attain a removal rate of 60% for H₂S and NO_x–N simultaneously. It took 34 and 48 days to attain the same removal rate for the reactor without inoculated sludge and the reactor inoculated with anaerobic sludge respectively. The reactor without inoculated sludge still operated successfully, despite requiring a slightly longer startup time. The packing material was capable of enhancing the removal efficiency of reactors. Based on the concentration of NO_x–N and H₂S in the effluent, the loading rate and the ability of the system to resist shock loading, the performance of the reactor filled with hollow plastic balls was greater than that of the reactor filled with elastic packing and the reactor filled with Pall rings.     

东方田鼠胚胎成纤维细胞的分离培养及生物学特性

目的对影响东方田鼠胚胎成纤维细胞（MfEF）分离和培养的因素进行探索,并观察其生物学特性。方法取室内繁殖饲养不同胎龄的东方田鼠胚胎分离成纤维细胞,通过原代和继代培养,分析比较不同胎龄、不同血清浓度、不同胰蛋白酶浓度等因素对MfEF分离及培养的影响,观察MfEF的生长形态及其生物学特性。结果 MfEF为贴壁型生长,细胞形态多样,呈梭形、不规则多边形;采用0.125%的胰蛋白酶室温消化12～13 d胚胎组织5 min,以DMEM培养基添加15%小牛血清分离培养MfEF的效果最佳;MfEF2～7代增殖最旺盛。结论获得了实验室分离、培养MfEF的有效方法 ,为进一步深入研究东方田鼠抗日本血吸虫机制以及开展不同动物成纤维细胞间比较研究奠定了基础。     

基因前定点敲入FLAG标签表达的FLAG-SND1蛋白参与胞内应激颗粒的形成

CRISPR/ Cas9 (clustered regular interspaced short palindromic repeats-Cas9 nuclease) gene editing technology is an emerging technology for gene-specific knock-out and knock-in in recent years. In this experiment, the CRISPR/ Cas9 gene editing system was used to insert 3×FLAG tags into the front of SND1 gene in HeLa cells, so that the endogenous expression of SND1 protein in cells was equipped with 3×FLAG tags, and the localization of SND1 with stress granules and processing bodies was observed. A sgRNA near the start codon ATG of the SND1 gene was designed, and a recombinant eukaryotic expression plasmid was constructed using px459 as an expression vector. A sequence containing 3×FLAG and a 150 bp homologous arm upstream and downstream of the position to be inserted was designed, and the recombinant plasmid was synthesized by the company. Two plasmids were co-transfected into HeLa cells, and positive cells were screened by puromycin. Western blotting indicated that the cells expressed the 3×FLAG-SND1 fusion protein. Genomic DNA was extracted and sequenced. Cell cycle and apoptosis were detected by flow cytometry after sequencing and the stable strain was obtained without error. It was found that there was no significant difference compared with WT cells. At the same time, the treatment with 0. 5 mmol / L sodium arsenite resulted in oxidative stress in cells, increased phosphorylation of eIF2α protein, and the presence of stress particles in the cytoplasm. There was co-localization between SND1 and stress particle marker protein TIAR, but no co-localization with processed body protein DCP1α. © 2019 The authors.     

On preprocessing and antisymmetry in de novo peptide sequencing: improving efficiency and accuracy

Peptide sequencing plays a fundamental role in proteomics. Tandem mass spectrometry, being sensitive and efficient, is one of the most commonly used techniques in peptide sequencing. Many computational models and algorithms have been developed for peptide sequencing using tandem mass spectrometry. In this paper, we investigate general issues in de novo sequencing, and present results that can be used to improve current de novo sequencing algorithms. We propose a general preprocessing scheme that performs binning, pseudo-peak introduction, and noise removal, and present theoretical and experimental analyses on each of the components. Then, we study the antisymmetry problem and current assumptions related to it, and propose a more realistic way to handle the antisymmetry problem based on analysis of some datasets. We integrate our findings on preprocessing and the antisymmetry problem with some current models for peptide sequencing. Experimental results show that our findings help to improve accuracies for de novo sequencing.     

Cloning and partial characterization of a gene in Bombyx mori homologous to a human adiponectin receptor

In this study, we report the cloning and characteristics of an adiponectin-like receptor gene from Bombyx mori (BmAdipoR) with highly conserved deduced amino-acid sequences and similar structure to the human adiponectin receptor (AdipoR). Structural analysis of the translated cDNA suggested it encoded a membrane protein with seven transmembrane domains. BmAdipoR was found to be expressed in multiple tissues and highly expressed in Malpighian tubules, fat body and testis. BmNPV (Bombyx mori nucleopolyhedrovirus) bacmid system combined with confocal microscopy revealed that BmAdipoR was targeted to the cell membrane. We also found that infection with BmNPV did not have an effect on BmAdipoR mRNA quantity in the midgut of susceptible Bombyx mori strain (306) at 48 h, but BmAdipoR mRNA quantity increased significantly at 72 h. We concluded that BmAdipoR gene was a membrane protein ubiquitously expressed in Bombyx mori tissues and that its expression was altered by treating with BmNPV.     

耐高糖高产2,3-丁二醇产酸克雷伯氏杆菌的选育

以产酸克雷伯氏杆菌(Klebsiella oxytoca) ME-UD-3为出发菌株,经紫外线及硫酸二乙酯复合诱变后分别在葡萄糖浓度逐渐提高的液体培养基中进行富集培养,筛选获得了一株耐高糖的2,3-丁二醇高产突变菌株K. oxytoca ME-UD-3-4;该菌株的初始葡萄糖耐受浓度从出发菌株的120g/L提高到300g/L以上,在初始葡萄糖浓度为95 g/L的条件下发酵培养,与出发菌株相比发酵时间缩短了8h,2,3-丁二醇的产量由原来的38.5g/L提高到43.0g/L,生产强度从0.80 g/L·h提高到1.08 g/L·h,转化率达到了理论值的91%。