长白山地区不同采集土样方式筛菌效率比较

目的对随机采样和田字格定点采样两种取样方式筛菌效率进行比较分析。方法利用随机采样和定点采样两种不同方式,采集了长白山地区的土样,取来自不同植物根际的土样,制成菌悬液后煮沸,涂布无氮平板以分离固氮芽胞杆菌。对分离的菌株进行菌落16S rDNA PCR,从中筛选鉴别巨大芽胞杆菌。结果定点采集土样分离出无晶体芽胞菌和有晶体芽胞菌分别是261株和76株,随机采集土样分离出无晶体芽胞菌和有晶体芽胞菌分别是279株和94株。经16S rDNA法鉴定分离巨大芽胞杆菌共19株。结论随机采样的取土方式与定点采样的取土方式差异度小,两种采集土样的方式在筛菌效率上并未表现出明显差异。     

Linear Rank Tests Derived from a Superpopulation Model

A superpopulation model generates the probabilities of a Bernouilli random variable. The ranks of the involved variables are considered as survey weights. The distribution f each linear rank statistic is derived under the null hypothesis for the two sample problem and for the case k2 when a simple random sampling or stratified sampling is used. The growth of a population of insects and the behavior of patients with imsomnia are studied using these procedures.     

Meta分析在细菌耐药性研究中的应用与展望

随着抗生素的大量不规范使用,细菌耐药性不断增强,导致耐药及多重耐药细菌的出现,严重威胁着人类健康。运用统计学方法对耐药性相关研究进行汇总与多元分析,有助于更好地了解全球细菌耐药性的流行与分布,明晰细菌耐药性形成规律与机制的共性问题。Meta分析是一种将多个同类型研究进行综合分析的统计学方法,已广泛应用于细菌耐药性的研究。本文简要描述了Meta分析的起源及基本流程,并采用文献计量的方法对2000-2020年关于Meta分析在细菌耐药性研究中的应用进行系统综述;进一步总结并阐述了Meta分析在细菌耐药性领域应用的成功案例和结论,而且对Meta分析方法在细菌耐药性领域中的进一步研究进行了展望,以期推动该方法在细菌耐药性研究中的应用,为耐药性问题的系统阐释和有效控制提供可靠的工具。     

均衡独立样本设计的研究

均衡独立样本设计是一种把独立样本设计与差异显著性检验相结合的试验设计．它基本上可以保证参试的优劣个体在所分样本（或组）间的分布相对均匀一致,使所分样本既具有独立性又具有均衡性,以增强对处理效果反应的灵敏度,提高试验的准确度．     

Estimation of abundance dynamics of gram-negative bacteria in soil

Bacterial succession in soil was studied for two variants of initiation (moistening and moistening with addition of glucose). To determine the numbers of viable gram-negative bacteria, the modified nalidixic acid method was applied. The numbers of gram-negative bacteria revealed by this method were 2 to 3.5 times higher than those determined by the traditional method. In a developing community, the highest total bacterial numbers were observed on day 7; afterwards their numbers decreased and stabilized at a level exceeding four-to fivefold the initial one. In both experimental variants, the highest numbers of viable gram-negative bacteria were revealed on day 15 (75–85% of the total bacterial numbers). Morphology of these bacteria suggests their classification as cytophagas (chitinophagas) utilizing chitin from the dead fungal mycelium.     

Genomic perspectives on the evolution and spread of bacterial pathogens

Since the first complete sequencing of a free-living organism, Haemophilus influenzae, genomics has been used to probe both the biology of bacterial pathogens and their evolution. Single-genome approaches provided information on the repertoire of virulence determinants and host-interaction factors, and, along with comparative analyses, allowed the proposal of hypotheses to explain the evolution of many of these traits. These analyses suggested many bacterial pathogens to be of relatively recent origin and identified genome degradation as a key aspect of host adaptation. The advent of very-high-throughput sequencing has allowed for detailed phylogenetic analysis of many important pathogens, revealing patterns of global and local spread, and recent evolution in response to pressure from therapeutics and the human immune system. Such analyses have shown that bacteria can evolve and transmit very rapidly, with emerging clones showing adaptation and global spread over years or decades. The resolution achieved with whole-genome sequencing has shown considerable benefits in clinical microbiology, enabling accurate outbreak tracking within hospitals and across continents. Continued large-scale sequencing promises many further insights into genetic determinants of drug resistance, virulence and transmission in bacterial pathogens.     

东北长白山垂直林带下现代表土花粉与植被关系

在长白山北坡5个垂直植被带的林下采集29个表土(苔藓)样品进行孢粉分析,同时将其结果作对应分析.结果表明,除个别样品,在长白山垂直植被带的孢粉组合中乔木花粉占优势,其中以松属和桦木属最多,在各植被带均有分布.松属花粉最高含量出现在以红松为主的针阔混交林带的孢粉组合中;桦木属花粉则大量见于亚高山岳桦林带和以栎桦为主的阔叶落叶林带,但前者伴有耐寒、早的小灌丛杜鹃花属花粉,而在后者中则见有大量蕨类孢子.阔叶落叶林带的孢粉组合是以类型多、百分含量高的落叶乔木花粉和大量蕨类孢子为特征.亚高山针叶林带的孢粉组合中出现数量众多的云杉属花粉.在高山苔原带孢粉组合中虽然乔木花粉略占优势,但极少或不见蕨类孢子,与其他植被带比较,草本植物和小灌丛花粉明鲜较多,其中杜鹃属花粉含量在草本中占优势,其中出现苔原带的指示花粉--仙女木属.     

Variability and Representativness of Lake Variables

This paper summarizes results from extensive field work in 95 Swedish lakes. It discusses four years (1986–1989) of monthly data on pH, Secchi depth, temperature, alkalinity, total-P, conductivity, Fe, Ca, hardness and colour. These variables vary both temporally and areally. The focus here is on such variations and patterns in variations, and how to express lake-typical values, not for specific sites and sampling occasions, but for entire lakes and longer periods of time (months-years). This is of importance in monitoring and validating models. A definition of total variability (TV), expressing variability between adjacent months within the year, and between the same month for different years, is presented. Selected results: An important pattern emerges for total-P with marked increases in TV during the summer and minimum values in winter. The pattern for colour shows lower TV during summer and higher TV during fall. The TV-values for pH are low and stable thoughout the year and no clear seasonal pattern can be seen. A seasonal pattern exists for conductivity, alkalinity, hardness, and Ca with higher TV during spring. The results concerning the variability within and between lakes show that the greatest differences exist for conductivity and Fe; the smallest (except temperature) for pH and alkalinity.     

Estimating the prevalence of infections in vector populations using pools of samples

Several statistical methods have been proposed for estimating the infection prevalence based on pooled samples, but these methods generally presume the application of perfect diagnostic tests, which in practice do not exist. To optimize prevalence estimation based on pooled samples, currently available and new statistical models were described and compared. Three groups were tested: (a) Frequentist models, (b) Monte Carlo Markov‐Chain (MCMC) Bayesian models, and (c) Exact Bayesian Computation (EBC) models. Simulated data allowed the comparison of the models, including testing the performance under complex situations such as imperfect tests with a sensitivity varying according to the pool weight. In addition, all models were applied to data derived from the literature, to demonstrate the influence of the model on real‐prevalence estimates. All models were implemented in the freely available R and OpenBUGS software and are presented in Appendix S1. Bayesian models can flexibly take into account the imperfect sensitivity and specificity of the diagnostic test (as well as the influence of pool‐related or external variables) and are therefore the method of choice for calculating population prevalence based on pooled samples. However, when using such complex models, very precise information on test characteristics is needed, which may in general not be available.     

东北长白山垂直林带下现代表土花粉与植被关系

在长白山北坡5个垂直植被带的林下采集29个表土(苔藓)样品进行孢粉分析，同时将其结果作对应分析。结果表明，除个别样品，在长白山垂直植被带的孢粉组合中乔木花粉占优势，其中以松属和桦木属最多，在各植被带均有分布。松属花粉最高含量出现在以红松为主的针阔混交林带的孢粉组合中；桦木属花粉则大量见于亚高山岳桦林带和以栎桦为主的阔叶落叶林带，但前者伴有耐寒、旱的小灌从杜鹃花属花粉，而在后者中则见有大量蕨类孢子。阔叶落叶林带的孢粉组合是以类型多、百分含量高的落叶乔木花粉和大量蕨类饱子为特征。亚高山针叶林带的孢粉组合中出现数量众多的云杉属花粉。在高山苔原带孢粉组合中虽然乔木花粉略占优势，但极少或不见蕨类孢子，与其他植被带比较，草本植物和小灌丛花粉明鲜较多，其中杜鹃属花粉含量在草本中占优势，其中出现苔原带的指示花粉——仙女木属。     

An approximate likelihood estimator for the prevalence of infections in vectors using pools of varying sizes

There are several arthropods that can transmit disease to humans. To make inferences about the rate of infection of these arthropods, it is common to collect a large sample of vectors, divide them into groups (called pools), and apply a test to detect infection. This paper presents an approximate likelihood point estimator to rate of infection for pools of different sizes, when the variability of these sizes is small and the infection rate is low. The performance of this estimator was evaluated in four simulated scenarios, created from real experiments selected in the literature. The new estimator performed well in three of these scenarios. As expected, the new estimator performed poorly in the scenario with great variability in the size of the pools for some values of the parameter space.     

Investigation of bacterioplankton in the loess-containing lake Khanka

Some characteristics of bacterioplankton—generation time, daily (P) and specific (P/B) bacterioplankton production, and bacterial metabolic coefficientK ₂—in the loess-containing Lake Khanka were determined using five modifications of the bacterial-count procedure with the fluorescent dyes fluorescamin and erythrosin. Experiments showed that the organomineral complex (OMC) in this lake is broken down by chemoorganoheterotrophic bacteria. The increase in the loess content of the lake water intensified bacterial growth and the cycles of potassium, silicon, and other biogenic elements. The addition of starch to a loess suspension activated the breakdown of OMC due to the adsorption of starch on the OMC/water interface and stimulation of the metabolism of attached bacteria.     

浙江晚稻稻种非致病细菌多样性初步研究

为了解特定生态环境中晚稻稻种的非致病细菌多样性以更有效地治理水稻主要病害,于1996－2001年间对采自浙江平原、丘陵及山区的606份稻种样本进行了非致病细菌种类、频率及对水稻纹枯病和恶苗病的抑菌作用研究。从中分离出9605个菌株,经致病性测定、菌落形态及部分细菌学特征（革兰氏染色、KMB培养基上的荧光色素和扩散性非荧光色素、YDC培养基上黄色菌落的产生、好气性、鞭毛及芽孢的染色镜检等）测定后,选出代表菌株622个,连同80个对照菌株用Biolog及脂肪酸分析法（FAME）进行测试。鉴定出Pseudomonas属11个种或型及其他14属的23种非致病细菌,并发现Pseudomonas属中55％的种及其他属中49％的种存在对水稻纹枯病或恶苗病的拮抗菌株,但不同种间的抑菌率存在较大差异。3类稻区均以Bacillus spp.、Acinetobacter spp.和P.putida等3个种群为主导并同时存在许多其他相似种,其中7个常见种的分离频率在不同稻区有显著差异。     

生物统计的各种检验方法和使用条件概述

生物统计的各种检验方法和使用条件概述房继明刘来福（北京师范大学生物学系,１００８７５）（北京师范大学数学系,１００８７５）ＡｎＯｕｔｌｉｎｅｏｆＴｅｓｔｉｎｇＭｅｔｈｏｄｓａｎｄＣｏｎｄｉｔｉｏｎｓｉｎＢｉｏｌｏｇｉｃａｌＳｔａｔｉｓｔｉｃｓ￥Ｆａｎ...     

Isolation and phylogenetic analysis of arcobacter spp. in ground chicken meat and environmental water in Japan and Thailand

Prevalence of Arcobacter spp. in chicken meat samples and environmental water samples in Japan and Thailand was investigated. Arcobacter was isolated from 48% of chicken meat samples (20/41) and 23% of river water samples (4/17) from Japan, and 100% of chicken meat samples (10/10) and 100% of canal water samples (7/7) from Thailand. A. butzleri was among the species isolated from all positive samples. About 10% genetic diversity was seen in the rpoB-rpoC in Arcobacters, and phylogenetic trees were divided into two clusters. In both countries, the results suggested that chicken and environmental water were highly contaminated with a genetically diverse population of Arcobacter.     

FtsZ and bacterial cell division

In this review we describe proteins and supermolecular structures which take part in the division of bacterial cells. FtsZ, a eukaryotic tubulin homolog is a key cell division protein in most prokaryotes. FtsZ, as well as tubulin, is capable of binding and hydrolyzing GTP. The division of a bacterial cell begins with the forming of a so-called divisome. The basis of such a divisome is a contractile ring (Z ring) which encircles the cell about midcell. The Z-ring consists of a bundle of laterally bound protofilaments formed in result of FtsZ polymerization. Z-ring is rigidly bounded to the cytosolic side of the inner membrane with the participation of FtsA, ZipA, FtsW and many other divisome cell division proteins. The ring directs the process of cytokinesis transmitting constriction power to the membrane. The primary structures of the prokaryotic FtsZ family members significantly differ from eukaryotic tubulins except for the sites of GTP binding. There is a high degree of structural homology between these proteins in the region. FtsZ is one of the most conserved proteins in prokaryotes. However, ftsZ genes have not been found in several species of microorganisms with completely sequenced genomes. They include two species of mycoplasmas (Ureaplasma parvum and Mycoplasma mobile), Prostecobacter dejongeii, 10 species of chlamydia and 5 species of archaea. Consequently, these organisms divide without FtsZ participation. The genomes of U. parvum and M. mobile have many open reading frames which encode proteins with unknown functions. A comparison of the primary structures of these hypothetical proteins did not identify any known cell division proteins. We hypothesize that the process of cell division in these organisms should involve proteins similar to FtsZ in function and homologous to FtsZ or other cell division proteins in structure.     

PCR技术检测猪肺炎支原体的研究进展

猪肺炎支原体(Mycopiasma hyopneumoniae)是引起猪支原体肺炎的重要病原,该病常引起继发感染和混合感染,严重威胁养猪业发展,造成巨大的经济损失.利用PCR技术对猪支原体肺炎早期正确诊断具有非常重要的意义.从猪肺炎支原体的特异性靶基因、临床样品采集方法与样品DNA处理方法、关键技术因素及普通PCR技术、多重PCR技术、套式PCR技术、荧光定量PCR技术、芯片检测和环介导等温扩增技术等在猪肺炎支原体检测中的研究进展、主要优缺点及应用进行综述.     

Tracking bacterial growth in liquid media and a new bacterial life model

By increasing viscosity of liquid media above 8.4 centipoise (cp) i.e. 0.084 g·cm~(-1)·S~(-1) individual growth and family formation of Escherichia coli was continuously observed in real-time for up to 6 h. The observations showed primarily unidirectional growth and reproduction of E. coli and suggested more than one reproduction in the observed portion of E. coli life span. A new bacterial life model is proposed: each bacterium has a stable cell polarity that ultimately transforms into two bacteria of different generations; the life cycle of a bacterium can contain more than one reproduction cycle; and the age of a bacterium should be defined by its experienced chronological time. This new bacterial life model differs from the dominant concepts of bacterial life but complies with all basic life principles based on direct observation of macroorganisms.