外源氮素调控C/N比对杉木林凋落叶细菌群落结构的影响

为探究不同C/N比对杉木凋落叶分解特性的影响,通过添加外源氮,采用分解袋法,分析林下植被保留和林下植被去除2种林分中不同C/N比值的杉木凋落叶分解300 d时细菌群落结构差异。研究显示：一定范围内,初始C/N比降低有利于杉木凋落叶分解和细菌群落多样性提升,过低的C/N比则具有抑制作用;相比于林下植被去除,林下植被保留管理措施更有利于杉木凋落叶的分解,且细菌群落多样性更高,但当初始C/N比值为20.3时,杉木凋落叶分解所受的抑制作用更为明显;在门水平上,变形菌门、放线菌门和浮霉菌门为杉木凋落叶中主要优势种群;在属水平上,慢生根瘤菌属、嗜酸栖热菌属和Singulisphaera属在杉木凋落叶中相对丰度较高;不同处理间的杉木凋落叶细菌群落结构具有显著差异,变形菌门、放线菌门和酸杆菌门等细菌门中的多类细菌相对丰度差异显著;在门分类水平上,杉木凋落叶C/N比值与主要细菌种群相对丰度的相关性最高,C/P比值与杉木凋落叶细菌群落结构变异的相关性最高;在属水平上,杉木凋落叶全碳含量、C/N比值和全钾含量与主要细菌种群相对丰度的相关性最高,全钾含量与杉木凋落叶细菌群落结构变异的相关性最高。结果表明初始C/N比的降低改变了杉木凋落叶细菌群落结构,进而作用于杉木凋落叶的分解。     

Design, synthesis, and biological activity of thiazole derivatives as novel influenza neuraminidase inhibitors

A series of novel influenza neuraminidase (NA) inhibitors based on thiazole core were synthesized and evaluated for their ability to inhibit NA of influenza A virus (H(3)N(2)). All compounds were synthesized in good yields starting from commercially available 2-amino-4-thiazole-acetic ester using a suitable synthetic strategy. These compounds showed moderate inhibitory activity against influenza A NA. The most potent compound of this series is compound 4d (IC(50)?=?3.43 μM), which is about 20-fold less potent than oseltamivir, and could be used to design novel influenza NA inhibitors that exhibit increased activity based on thiazole ring.     

Variations of chemical composition and energy content in natural and genetically defined cultivars of Macrocystis from Chile

Seasonal and intra-thallus variations of energy content and chemical composition were assessed in an intertidal population of Macrocystis in southern Chile. Phylloid protein and lipid from cultured material were compared with seasonal variation in native Macrocystis. Furthermore, populations in northern and southern Chile and Falkland Islands were compared with various intra-/inter-cultivar genotypes of Chilean Macrocystis. Energetic values did not show seasonal or intra-thallus variations, with the exception of pneumatocysts, which had high levels of ash (49.9% DW) and low values of total energy (8.3% DW). Seasonal patterns were detected in protein and carbohydrate composition, with opposite trends. Likewise, holdfasts contained high amounts of protein (21.0% DW), and phylloids were high in soluble carbohydrates (4.5% DW). Lipids instead showed two peaks per year in an intertidal population and reached up to 0.4% DW. Alginic acid was the major organic compound in intertidal Macrocystis (46.8% DW), with differences on seasonal and intra-thallus levels. Mannitol content, in contrast, was erratic and lower than in other Laminariales (<5% DW). In general, protein and lipid content in our cultivars were 20% higher than in natural populations. Our experimental results indicate the possibility to manipulate the chemical composition of Macrocystis thalli through inter-/intra-specific crosses. This will be a basis, upon which selected genotypes can open new perspectives to Macrocystis mariculture industries in Chile.     

温带森林不同演替阶段下的土壤CO2排放通量昼间变化

采用时空替代法,在长白山北坡分别选取了红松针阔叶混交林演替序列的5个不同阶段:草地、灌木林(幼龄林)地、白桦林地、阔叶杂木林地和红松阔叶林地,进行土壤CO_2排放通量昼间变化野外同步观测研究,旨在揭示温带森林不同演替阶段下的土壤呼吸CO_2排放过程的差异,探究其与温度、湿度、土壤理化性质等环境因子的关系。结果表明:(1)温带森林不同演替阶段下的土壤CO_2排放通量具有统一性,均为大气CO_2的源,这种统一性确保了小的时段(如昼间)观测能通过换算,实现CO_2排放量的估算。(2)CO_2排放通量的昼间排放都呈现出明显的单峰型,峰值在13:00—15:00左右,草地和灌木林地的峰值大概在13:00左右,明显提前于白桦林地、阔叶杂木林地和红松阔叶林地(14:00—15:00左右)。红松阔叶林地的土壤呼吸有明显的滞后性特征,峰值在15:00左右,比其他几个样地明显推迟。(3)土壤CO_2排放通量平均值由低到高排列依次为草地(2.760μmol m~(-2)s~(-1))、灌木林地(2.854μmol m~(-2)s~(-1))、白桦林地(3.048μmol m~(-2)s~(-1))、阔叶杂木林地(3.696μmol m~(-2)s~(-1))、红松阔叶林地(4.61μmol m~(-2)s~(-1))。随着温带森林演替的正向进行,土壤CO_2排放通量依次增大,次序为草地灌木林地白桦林地阔叶杂木林地红松阔叶林地。(4)环境因子中,0—5 cm土壤温度与土壤CO_2排放通量相关系数最高,土壤温度监测对土壤CO_2排放量的估算作用明显。     

通过二代测序技术开发25个小熊猫的微卫星位点

采用Roche 454基因组测序平台在小熊猫Ailurus fulgens的基因组中进行测序拼装,得到了大量含有微卫星片段的序列。本文选择了其中467条序列设计引物,筛选出了115个微卫星位点,最终选出25个微卫星位点,重复单元包含TAT、GATA、AAACA、AAAACA等,并应用到42只小熊猫个体上进行了分型。观察到的等位基因数为3～10;观察杂合度和期望杂合度分别为0. 143～0. 929和0. 136～0. 869;多态信息含量为0. 128～0. 843,经检测所有位点均未偏离哈迪-温伯格平衡。这些微卫星位点可应用于小熊猫圈养种群的遗传管理,在未来还可进一步作为小熊猫的种群遗传学等研究的有力工具。     

A redescription of Liangwangshania biloba Chen, 2005, from the Chengjiang biota (Cambrian,China), with a discussion of possible sexual dimorphism in fuxianhuiid arthropods

Material attributed to Liangwangshania biloba, a fuxianhuiid arthropod from the lower Cambrian (Series 2, Stage 3) of southwest China, is redescribed, with many specimens illustrated for the first time. Newly recognized features include, potential optical neuropils, a stout posterolateral carapace spine, serrated tergal pleurae, two rows of mediolateral carinae, an abdomen composed of seven segments, the last possessing a tripartite lateral flap, and a triangular telson. The presence of tergal carinae, a prothorax composed of six segments, and a trunk composed of 43 segments tipped with a flap-like terminal segment, increase similarities with the previously described Shankouia zhenghei, thus prompting a reevaluation of the potential synonymy of these taxa. These previously recognized species also show considerable overlap in body size, and the ratios of selected body features, such as the carapace. This, combined with their co-occurrence over a temporally and geographically limited range, further support their synonymy. L. biloba is considered the senior synonym in accordance with ICZN rulings, with morphological differences, specifically the presence of posterolateral spines on the carapace, serrated tergopleurae, and spines on the terminal abdominal segment, attributed to sexual variation. An evaluation of potential sexual dimorphism in other fuxianhuiids, and a reassessment of terminology applied to this group is also provided.     

长白山苔原草本植物入侵与土壤环境的关系

在对长白山高山苔原西坡样带内132个样方进行植被调查和土壤取样分析的基础上,应用冗余分析(RDA)和典型相关分析方法,探讨了草本植物入侵苔原带程度与苔原土理化性质及环境之间的关系。研究表明,长白山苔原带西坡草本入侵程度区域差异明显,可分为5个不同的入侵等级;海拔、坡度、全钾含量、粘粒含量、有机质含量等10种土壤环境因子与草本植物入侵程度明显相关。RDA分析表明土壤环境因子能解释93%的植物物种多度信息,影响草本植物入侵的主要土壤因子是有机质含量,粘粒含量和坡度;第一对典型变量说明有机质含量与牛皮杜鹃多度正相关,与大白花地榆多度负相关,粘粒含量则相反;第二对典型变量说明海拔、速效氮含量与笃斯越桔、长白老鹳草多度呈负相关。长白山苔原带西坡草本植物在空间分布上是离散的,呈斑块状。可见,草本植物入侵,对生境是有所选择的。土壤有机质含量与灌木多度呈正相关,说明在草本入侵过程中,土壤有机质含量会减少;或者有机质含量减少的地方,灌木生长退化,草本由此开始侵入定植。     

Probe-free allele-specific copy number detection and analysis of tumors

Cancer development and progression frequently involve nucleotide mutations as well as amplifications and deletions of genomic segments. Quantification of allele-specific copy number is an important step in characterizing tumor genomes for precision medicine. Despite advances in approaches to high-throughput genomic DNA analysis, inexpensive and simple methods for analyzing complex nucleotide and copy number variants are still needed. Real-time polymerase chain reaction (PCR) methods for discovering and genotyping single nucleotide polymorphisms are becoming increasingly important in genetic analysis. In this study, we describe a simple, single-tube, probe-free method that combines SYBR Green I-based quantitative real-time PCR and quantitative melting curve analysis both to detect specific nucleotide variants and to quantify allele-specific copy number variants of tumors. The approach is based on the quantification of the targets of interest and the relative abundance of two alleles in a single tube. The specificity, sensitivity, and utility of the assay were demonstrated in detecting allele-specific copy number changes critical for carcinogenesis and therapeutic intervention. Our approach would be useful for allele-specific copy number analysis or precise genotyping.     

Design of a sandwich-mode amperometric biosensor for detection of PML/RARα fusion gene using locked nucleic acids on gold electrode

In this study, a novel DNA electrochemical probe (locked nucleic acid, LNA) was designed and involved in constructing an electrochemical DNA biosensor for detection of promyelocytic leukemia/retinoic acid receptor alpha (PML/RARα) fusion gene in acute promyelocytic leukemia for the first time. This biosensor was based on a 'sandwich' sensing mode, which involved a pair of LNA probes (capture probe immobilized at electrode surface and biotinyl reporter probe as an affinity tag for streptavidin-horseradish peroxidase (streptavidin-HRP). Since biotin can be connected with streptavidin-HRP, this biosensor offered an enzymatically amplified electrochemical current signal for the detection of target DNA. In the simple hybridization system, DNA fragment with its complementary DNA fragment was evidenced by amperometric detection, with a detection limit of 74 fM and a linear response range of 0.1-10 pM for synthetic PML/RARα fusion gene in acute promyelocytic leukemia (APL). Otherwise, the biosensor showed an excellent specificity to distinguish the complementary sequence and different mismatch sequences. The new pattern also exhibited high sensitivity and selectivity in mixed hybridization system.