Mitogenomes provide new insights of evolutionary history of Boreheptagyiini and Diamesini (Diptera: Chironomidae: Diamesinae)

Mitogenomes have been widely used for phylogenetic reconstruction of various Dipteran groups, but specifically for chironomid, they have not been carried out to resolve the relationships. Diamesinae (Diptera: Chironomidae) are important bioindicators for freshwater ecosystem monitoring, but its evolutionary history remains uncertain for lack of information. Here, coupled with one previously published and 30 new mitogenomes of Diamesinae, we carried out comparative mitogenomic analysis and phylogenetic analysis. Mitogenomes of Diamesinae were conserved in structure, and all genes arranged in the same order as the ancestral insect mitogenome. All protein‐coding genes in Diamesinae were under stronger purifying selection than those of other nonbiting midge species, which may exhibit signs of adaptation to life at cold living conditions. Phylogenetic analyses strongly supported the monophyly of Diamesinae, with Boreheptagyiini deeply nested within Diamesini. In addition, phylogenetic relationship of selected six genera was resolved, except Sympotthastia remained unstable. Our study revealed that the mitogenomes of Diamesinae are highly conserved, and they are practically useful for phylogenetic inference.     

基于蛋白质二级结构热稳定性的正交方法

对蛋白质热稳定性的研究是解析蛋白高级结构,开发蛋白功能及新药物研发过程中的一个重要环节,是对其结构分析的一个重要关切点.观测蛋白质的圆二色光谱随温度程序变化而改变是研究其热稳定性的常用手段,传统的实验方法为选用某一单波长作为测试点,通过连续升温测试蛋白在单波长下的圆二色变温曲线,然后拟合出Tm值,此方法所得的信息有限,...     

湘南典型次生林粗木质残体生物量、碳储量和养分特征

对九龙江森林公园次生常绿阔叶林粗木质残体(CWD)进行量化研究,了解亚热带典型次生林CWD的本底数据。以九龙江森林公园典型天然次生林中的6个20m×20m的标准样地为对象,调查并分析样地内不同分解等级CWD的生物量、碳储量和养分特征变化。九龙江森林公园亚热带典型次生林的CWD储量在2.8—30.4t/hm~2之间,碳储量在6.10—6.75t/hm~2之间,大量营养元素(N、P、K、 Ca、 Mg)含量相对稳定,化学计量变化不显著,微量营养元素中Pb与Cd元素含量随着分解等级的增加而增加。九龙江森林公园亚热带典型次生林的CWD储量在亚热带常绿阔叶林中处于中等水平,CWD主要以分解中后期的倒木为主,反映出该次生林处于中幼龄林阶段,具有较高的碳储量,养分含量相对稳定,并表现出Pb与Cd在CWD中积累的现象,在中度分解和重度分解的CWD中Pb含量分别增加了62.65%和69.88%,Cd含量则分别增加了33.33%和100%,其内在机理有待进一步深入研究。研究结果有助于进一步了解CWD如何参与森林生态系统养分循环、重金属积累等生态过程,比较不同林分干扰历史下CWD储量、分布及养分特征的异质性...     

High auxin stimulates callus through SDG8-mediated histone H3K36 methylation in Arabidopsis

Callus induction,which results in fate transition in plant cells,is considered as the first and key step for plant regeneration.This process can be stimulated in different tissues by a callus-inducing medium(CIM),which contains a high concentration of phytohormone auxin.Although a few key regulators for callus induction have been identified,the multiple aspects of the regulatory mechanism driven by high levels of auxin still need further investigation.Here,we find that high auxin induces callus ...     

Gut microbiome in gastrointestinal cancer: a friend or foe?

The impact of the gut microbiome on host health is becoming increasingly recognized. To date, there is growing evidence that the complex characteristics of the microbial community play key roles as potential biomarkers and predictors of responses in cancer therapy. Many studies have shown that altered commensal bacteria lead to cancer susceptibility and progression in diverse pathways. In this review, we critically assess the data for gut microbiota related to gastrointestinal cancer, including esophageal, gastric, pancreatic, colorectal cancer, hepatocellular carcinoma and cholangiocarcinoma. Importantly, the underlying mechanisms of gut microbiota involved in cancer occurrence, prevention and treatment are elucidated. The purpose of this review is to provide novel insights for applying this understanding to the development of new therapeutic strategies in gastrointestinal cancer by targeting the microbial community.     

Direct adenylation from 5′-OH-terminated oligonucleotides by a fusion enzyme containing Pfu RNA ligase and T4 polynucleotide kinase

5′-Adenylated oligonucleotides (AppOligos) are widely used for single-stranded DNA/RNA ligation in next-generation sequencing (NGS) applications such as microRNA (miRNA) profiling. The ligation between an AppOligo adapter and target molecules (such as miRNA) no longer requires ATP, thereby minimizing potential self-ligations and simplifying library preparation procedures. AppOligos can be produced by chemical synthesis or enzymatic modification. However, adenylation via chemical synthesis is inefficient and expensive, while enzymatic modification requires pre-phosphorylated substrate and additional purification. Here we cloned and characterized the Pfu RNA ligase encoded by the PF0353 gene in the hyperthermophilic archaea Pyrococcus furiosus. We further engineered fusion enzymes containing both Pfu RNA ligase and T4 polynucleotide kinase. One fusion enzyme, 8H-AP, was thermostable and can directly catalyze 5′-OH-terminated DNA substrates to adenylated products. The newly discovered Pfu RNA ligase and the engineered fusion enzyme may be useful tools for applications using AppOligos.     

1956-2009年内蒙古苏尼特左旗荒漠草原的降水格局

弄清全球变化背景下不同地区降水格局的变化对科学理解气候变化及其影响具有重要意义。苏尼特左旗荒漠草原是温带干旱半干旱地区的典型荒漠草原,对气候变化,特别是降水变化非常敏感。利用1956-2009年的日降水资料探讨了苏尼特左旗荒漠草原降水格局的变化规律,以为揭示气候变化的影响机制提供依据。结果表明,该地区年均降水量为191.9 mm,年际变化剧烈,变异系数达26.63%;年均降水日数为63.8 d,变异系数16.9%。生长季降水占全年的85%,但各月变异系数均>50%;降水日数占全年的63%。年和生长季的各月降水以中等降水量、弱降水日数为主,中等强度以上降水事件较少。近50 a来,年和生长季的降水量、降水日数与各等级降水事件均呈下降趋势,年降水减少的原因在于中等降水事件的减少、生长季降水减少的原因在于弱降水事件的减少。年降水减少将影响草地的土壤水分与植物返青;而生长季降水减少将直接影响草地固碳。气候变化背景下年与生长季降水的减少将进一步加剧该地区干旱程度并影响植物的生长发育,从而直接威胁到草地畜牧业的发展。     

景观生态学在土地整治中的应用研究进展

在土地整治中融入景观生态学理念是推动土地整治生态建设的必然要求。阐述了土地整治中的景观生态学原理,分析了相关文献变化和研究重点,总结了中国土地整治中的景观生态学研究现状,提出了土地整治中的景观生态学研究展望:(1)重视土地整治中景观生态学的基础理论研究,构建土地整治的景观生态学理论与技术体系;(2)加强土地整治的景观动态与生态效应机制研究,建立适用土地整治景观生态影响的方法和模型;(3)强化土地整治的多尺度和长序列景观生态研究,揭示土地整治过程中的尺度效应和多尺度耦合机制;(4)加强土地整治中多种生态系统服务的集成与优化,强化用于指导土地整治生态规划设计与管理工作,以期为深化土地整治中的景观生态学研究提供借鉴和启示。     

五年制临床医学专业微生物“细菌学”教学实践与思考

医学微生物学属于基础医学教育的主干课程,是基础医学向临床医学课程过渡的桥梁课程。医学微生物学中关于细菌学的部分是整个微生物学的核心内容之一,包括细菌的生物学特性、致病性、免疫性、检测方法及防治原则等。传统的授课模式是在系统讲解这些基本知识的基础上,补充细菌学实验的基本技能及操作方法,不过从实际教学效果来看,传统的教学模式暴露出了一些弊端。我们根据医学微生物学知识内容的特点,结合其中细菌学研究的历史和规律,系统讨论了如何有效提升课堂教学质量,激发学生的学习兴趣和创新精神,重点培养学生发现问题、思考问题以及解决问题的能力。