Role of extracellular polymeric substance (EPS) in toxicity response of soil bacteria Bacillus sp. S3 to multiple heavy metals

Heavy metal resistant bacteria are of great interest because of their potential use in bioremediation. Understanding the survival and adaptive strategies of these bacteria under heavy metal stress is important for better utilization of these bacteria in remediation. The objective of this study was to investigate the role of bacterial extracellular polymeric substance (EPS) in detoxifying against different heavy metals in Bacillus sp. S3, a new hyper antimony-oxidizing bacterium previously isolated from contaminated mine soils. The results showed that Bacillus sp. S3 is a multi-metal resistant bacterial strain, especially to Sb(III), Cu(II) and Cr(VI). Toxic Cd(II), Cr(VI) and Cu(II) could stimulate the secretion of EPS in Bacillus sp. S3, significantly enhancing the adsorption and detoxification capacity of heavy metals. Both Fourier transform infrared spectroscopy (FTIR) and three-dimensional excitation–emission matrix (3D-EEM) analysis further confirmed that proteins were the main compounds of EPS for metal binding. In contrast, the EPS production was not induced under Sb(III) stress. Furthermore, the TEM–EDX micrograph showed that Bacillus sp. S3 strain preferentially transported the Sb(III) to the inside of the cell rather than adsorbed it on the extracellular surface, indicating intracellular detoxification rather than extracellular EPS precipitation played an important role in microbial resistance towards Sb(III). Together, our study suggests that the toxicity response of EPS to heavy metals is associated with difference in EPS properties, metal types and corresponding environmental conditions, which is likely to contribute to microbial-mediated remediation.

     

Epidemiological,Clinical and Serological Characteristics of Children with Coronavirus Disease 2019 in Wuhan: A Single-centered,Retrospective Study

In December 2019, SARS-CoV-2 was first detected in the samples obtained from three adult patients who suffered from an unknown viral pneumonia in Wuhan (Li et al. 2020). This unknown viral pneumonia is further named as coronavirus disease 2019 (COVID-19) by the World Health Organization. To date, the number of new COVID-19 cases has continued to skyrocket and the impact of SARS-CoV-2 on humans is far greater than any pathogen of this century in both breadth and depth. Previous studies have shown that adults with COVID-19 have symptoms of fever, dry cough, dyspnea, fatigue and lymphocytopenia. Moreover, COVID-19 is more likely to cause death in the elderly, especially those with chronic comorbidities (Huang et al. 2020). In Wuhan, more than 50, 000 COVID-19 cases have been confirmed, including over 780 pediatric patients, and only one child death case (Lu et al. 2020). Although the number of children cases was far fewer than that of adults, COVID-19 might endanger children's health and the information on children remains limited, especially in serological study. In the retrospective study, the investigators analyzed the epidemiological, clinical and serological characteristics of children with COVID-19 in Wuhan in the early stages of the outbreak, which might provide theoretical and practical help in controlling COVID-19 and similar emerging infectious diseases in the future.     

不同温度下稻螟赤眼蜂在黏虫卵上的种群生命表

稻螟赤眼蜂Trichogramma japonicum Ashmead是水稻二化螟Chilo suppressalis(Walker)的优势卵寄生蜂。本文构建了以黏虫卵为中间寄主,稻螟赤眼蜂在20℃、25℃、30℃、33℃四个温度条件下的生命表。研究结果表明利用黏虫卵繁育稻螟赤眼蜂时,不同温度下其生长发育和繁殖均存在显著差异,雌蜂平均寿命随温度的升高呈下降趋势,在20℃条件下,雌蜂平均寿命为1.44 d,显著长于其它温度,当温度为30~33℃时,雌蜂寿命最短,平均为0.59 d。在温度为20℃和25℃时,稻螟赤眼蜂的羽化率显著高于温度较高的30℃和33℃,平均为94.73%。在25℃条件下,黏虫卵繁育的稻螟赤眼蜂的净生殖力(R 0)最大,达到31.9176,单雌寄生卵数最多,为32.88个,表现出最强的繁殖能力,而在30℃条件下,瞬时增长率r m和周限增长率λ达到最大值。综合生命表参数、单雌寄生黏虫卵数、寿命、羽化率等指标,利用黏虫卵工厂化繁殖稻螟赤眼蜂的最佳温度为25℃。本研究为利用黏虫卵大量繁殖稻螟赤眼蜂提供了有价值的参考。     

Long-Term Existence of SARS-CoV-2 in COVID-19 Patients: Host Immunity,Viral Virulence,and Transmissibility

Virologica Sinica - COVID-19 patients can recover with a median SARS-CoV-2 clearance of 20 days post initial symptoms (PIS). However, we observed some COVID-19 patients with existing...     

Epitranscriptomic technologies and analyses

RNA can interact with RNA-binding proteins(RBPs), mRNA, or other non-coding RNAs(ncRNAs) to form complex regulatory networks. High-throughput CLIP-seq, degradome-seq, and RNA-RNA interactome sequencing methods represent powerful approaches to identify biologically relevant ncRNA-target and protein-ncRNA interactions. However, assigning ncRNAs to their regulatory target genes or interacting RNA-binding proteins(RBPs) remains technically challenging. Chemical modifications to mRNA also play important roles in regulating gene expression. Investigation of the functional roles of these modifications relies highly on the detection methods used. RNA structure is also critical at nearly every step of the RNA life cycle. In this review, we summarize recent advances and limitations in CLIP technologies and discuss the computational challenges of and bioinformatics tools used for decoding the functions and regulatory networks of ncRNAs. We also summarize methods used to detect RNA modifications and to probe RNA structure.     

Shortened snRNA promoters for efficient CRISPR/Cas-based multiplex genome editing in monocot plants

正Dear Editor,CRISPR (clustered regularly interspaced short palindromic repeats)/Cas genome editing is a powerful tool for introducing specific mutations in organisms including plants. The system is composed of a nuclease such as Cas9 or Cas12a and an engineered single-guide RNA (sgRNA) incorporating a target sequence (Li et al., 2019). A Cas9/sgRNA complex re-     

阿加曲班对MCAO大鼠不同时间点血小板功能的影响

建立大脑中动脉闭塞(model of middle cerebral artery occlusion,MCAO)大鼠模型,研究阿加曲班对大鼠不同时间脑缺血再灌注损伤血小板功能的影响。将120只健康雄性SD大鼠随机分为假手术组(Sham)、模型组(Model)和阿加曲班给药组(Argatroban),其中Argatroban组分为4组:Argatroban+30 min组、Argatroban+1 h组、Argatroban+3 h组和Argatroban+7 h组,Sham组和Model组40只,其余各组每组10只。线栓法制备大鼠MCAO模型,术中输注Argatroban,剂量为0.3μg·kg^-1·min^-1,完成手术前5 min停止输注。手术完成后,Sham组和Model组分别于术后30 min、1 h、3 h和7 h处死10只取样;Argatroban给药组5个时间点处死取样。检测大鼠血浆血细胞数量,并计数骨髓有核细胞数的变化。采用流式细胞仪检测血小板-白细胞聚集体(platelet-leukocyte aggregates,PLA)表达水平,观察活化部分凝血活酶时间(activated partial thromboplastin time,APTT)、血小板计数变化,ELISA检测血浆D-二聚体和TAT。结果显示,与Sham组相比,Model组大鼠的红细胞(RBC)、白细胞(WBC)、血红蛋白含量(HGB)和中性粒细胞(GR)数都显著升高(p<0.05),且与给药组没有统计学差异。Sham组、Model组和Argatroban给药组的骨髓有核细胞数也没有统计学差异。与Sham组相比,Model组PLA表达水平极显著升高(p<0.01),Argatroban+30 min组PLA表达水平却低于Sham组,但没有统计学差异,Argatroban+1 h组高于Sham组和Argatroban+30 min组(p<0.05),Argatroban+3 h组和Argatroban+7 h组高于Argatroban+1 h组低于Sham组。术后各组的血小板计数均高于Sham组(p<0.05),Argatroban各组的血小板计数要低于Model组(p<0.05),并在30 min时达到最低,30 min以后血小板升高,但是1 h以后血小板不再升高,趋于稳定。Argatroban各组PT和APTT虽略有降低,但是与Sham组和Model组并没有统计学差异。造模后各组TAT、D-二聚体水平显著升高,Argatroban各组TAT水平较模型组明显降低(p<0.05),Argatroban+30 min组水平最低。MCAO模型大鼠血液呈现高凝状态,凝血功能和纤维蛋白溶解功能亢进,血小板活化增强,阿加曲班可对此起到改善作用。     

盐酸右美托咪定联合瑞芬太尼在骨科手术中的应用效果及对呼吸功能的影响

本研究考察了盐酸右美托咪定联合瑞芬太尼(观察组,n=68)和丙泊酚联合瑞芬太尼(对照组,n=68)在我院136例骨科手术患者中的应用效果,应用警觉/镇静观察评分(OAA/S)评价患者用药前(T0)、用药10 min后(T1)、用药20 min后(T2)、用药30 min后(T3)和清醒后(T4)的镇静效果,并比较了两组患者在不同时间点的呼吸频率(RR)、血氧饱和度(SpO2)、心率(HR)和平均动脉压(MAP)。研究结果显示,两组患者在T0、T1和T4时间点的OAA/S评分无统计学差异(p>0.05),观察组在T2和T3时间点的OAA/S评分明显小于对照组(p<0.05)。两组患者在T0、T1和T4时间点的RR无统计学差异(p>0.05),观察组在T2和T3时间点时的RR明显大于对照组(p<0.05)。观察组在T2时间点时的SpO2明显大于对照组(p<0.05)。两组患者的SpO2在其他时间段时无明显差异(p>0.05)。两组患者的HR和MAP均未表现出明显差异(p>0.05)。观察组的不良反应发生率为2.94%,明显高于对照组的11.76%(p=0.049)。本研究结论初步表明,与丙泊酚联合瑞芬太尼相比,盐酸右美托咪定联合瑞芬太尼在骨科手术中具有更好的镇静效果,可有效保障患者的呼吸功能,具有良好的血流动力学稳定性和安全性。     

Molecular phylogeny and species delimitation of Stachyuraceae: Advocating a herbarium specimen‐based phylogenomic approach in resolving species boundaries

Species concept and delimitation are fundamental to taxonomic and evolutionary studies. Both inadequate informative sites in the molecular data and limited taxon sampling have often led to poor phylogenetic resolution and incorrect species delineation. Recently, the whole chloroplast genome sequences from extensive herbarium specimen samples have been shown to be effective to amend the problem. Stachyuraceae are a small family consisting of only one genus Stachyurus of six to 16 species. However, species delimitation in Stachyurus has been highly controversial because of few and generally unstable morphological characters used for classification. In this study, we sampled 69 individuals of seven species (each with at least three individuals) covering the entire taxonomic diversity, geographic range, and morphological variation of Stachyurus from herbarium specimens for genome‐wide plastid gene sequencing to address species delineation in the genus. We obtained high‐quality DNAs from specimens using a recently developed DNA reconstruction technique. We first assembled four whole chloroplast genome sequences. Based on the chloroplast genome and one nuclear ribosomal DNA sequence of Stachyurus, we designed primers for multiplex polymerase chain reaction and high throughput sequencing of 44 plastid loci for species of Stachyurus. Data of these chloroplast DNA and nuclear ribosomal DNA internal transcribed spacer sequences were used for phylogenetic analyses. The phylogenetic results showed that the Japanese species Stachyurus praecox Siebold & Zucc. was sister to the rest in mainland China, which indicated a typical Sino‐Japanese distribution pattern. Based on diagnostic morphological characters, distinct distributional range, and monophyly of each clade, we redefined seven species for Stachyurus following an integrative species concept, and revised the taxonomy of the family based on previous reports and specimens, in particular the type specimens. Furthermore, our divergence time estimation results suggested that Stachyuraceae split from its sister group Crossosomataceae from the New World at ca. 54.29 Mya, but extant species of Stachyuraceae started their diversification only recently at ca. 6.85 Mya. Diversification time of Stachyurus in mainland China was estimated to be ca. 4.45 Mya. This research has provided an example of using the herbarium specimen‐based phylogenomic approach in resolving species boundaries in a taxonomically difficult genus.