Characterization of antimicrobial resistance among Escherichia coli isolates from chickens in China between 2001 and 2006

Escherichia coli is a common commensal bacterium and is regarded as a good indicator organism for antimicrobial resistance for a wide range of bacteria in the community and on farms. Antimicrobial resistance of E. coli isolated from chickens from 49 farms in China between 2001 and 2006 was studied. A total of 536 E. coli isolates were collected, and minimal inhibitory concentrations (MICs) of eight antimicrobials were determined by the broth microdilution method. Isolates exhibited high levels of resistance to ampicillin (80.2%), doxycycline (75.0%) and enrofloxacin (67.5%). Relatively lower resistance rates to cephalothin (32.8%), cefazolin (17.0%) and amikacin (6.5%) were observed. Strains were comparatively susceptible to colistin (MIC(50)=1 mug mL(-1)). A marked increase in isolates with elevated MICs for florfenicol was observed over the study period. Therefore, five resistance genes leading to the dissemination of phenicol resistance in the isolates (n=113) with florfenicol MICs>/=32 mug mL(-1) were analyzed. The gene floR was the most prevalent resistance gene and was detected in 92% of the 113 isolates, followed by the cmlA (53%), catA1 (23%) and catA2 (10%) genes. catA3 was not detected in these isolates. Eight isolates with florfenicol MICs=32 mug mL(-1) and one with MIC=64 mug mL(-1) were negative for the floR gene.     

Pyrazolopyrimidine metabolism in Leishmania and trypanosomes: significant differences between host and parasite

The pathogenic hemoflagellates of the genera Leishmania and Trypanosoma are major causes of human disease in the tropical and subtropical areas of the world. In general, the agents used to treat diseases caused by these organisms are toxic and not suitable for administration to the millions of people infected. Investigations over the past several years have shown that there are several major differences between man and these protozoans with respect to purine metabolism. The differences appear to offer promise for the development of effective chemotherapeutic compounds. These organisms do not synthesize purines de novo, as does man. They are able to concentrate pyrazolopyrimidines with the cell and metabolize them as purines through the salvage pathways, ultimately incorporating them into nucleic acids. This does not occur in mammals. The pyrazolopyrimidine base allopurinol, which has served as a prototype, is activated by a phosphoribosyltransferase to the ribonucleotide. The ribonucleotide is aminated to the 4-amino-pyrazolopyrimidine ribonucleotide and subsequently phosphorylated to the triphosphate form and incorporated into RNA. The pyrazolopyrimidine ribonucleosides formycin B and allopurinol ribonucleoside are activated through a nucleoside phosphotransferase. The resulting ribonucleotide is aminated and incorporated into RNA as described above. These metabolic peculiarities occur not only in the forms of these parasites which are found in the insect vectors but also in the intracellular forms which are pathogenic in man. The differences in the enzymology and metabolism of purines which exist in the genera Leishmania and Trypanosoma offer excellent opportunities for chemotherapeutic exploitation.     

中国蛱蝶科昆虫地理分布与区系分析

分析了中国蛱蝶科已知324种昆虫的分布与区系组成,主要由古北区、东洋区、古北一东洋区共有种类组成,共计309种,占总数的95．37％;其种类组成与澳洲区、新北区有明显差异;特有种类较少,占总数的12．65％;广布种很少,仅占1．74％。同时统计分析了324种蛱蝶在我国各省的贫富指数。     

中国东部与西部汉族小学生体质发育差异的动态变化

为了揭示中国东西部汉族小学生体质发育差异的动态变化,应用文献资料法和数理统计法,将中国学生体质与健康1985年和2010年两次调研中有关东部和西部汉族小学生体质数据进行统计和对比分析。结果表明:东部小学生体质持续优于西部小学生且总体上差异具有统计学意义(P<0.05),东西部小学生的身体形态、身体机能及城市小学生体育素质呈拉大的趋势,东西部乡村小学生的体育素质呈缩小的趋势;东西部小学生身体形态发育处于增长的长期趋势;东西部小学生肺活量全面下降具有统计学意义(P<0.05),西部小学生下降速度快于东部小学生;东西部小学生耐力跑全面下降而斜身引体全面提高且具有统计学意义(P<0.05);东西部小学生体育素质发展差异的特征比较明显,东部小学生体育素质项目提高数量、幅度和速度高于西部小学生而下降的数量、幅度和速度低于西部小学生。     

不同地理种群银杏大蚕蛾COI基因序列变异与遗传分化

银杏大蚕蛾Caligula japonica是亚洲东部的特有种, 既是一种重要的林业害虫, 也是一种珍贵的野生蚕类资源。为了揭示银杏大蚕蛾地理种群间的内在联系, 测定了我国分布的12个地理种群的线粒体细胞色素氧化酶C亚基I（COI）基因部分序列（GenBank登录号: FJ358506-FJ358517）, 对地理种群间的序列变异和遗传分化进行了分析。结果表明: 银杏大蚕蛾地理种群间的COI序列同源性高达99%~100%, 显示出比较小的遗传差异。序列对准后从供试COI序列中仅鉴定出9个变异位点和6个单元型, 其中3种是共享单元型。系统发育分析结果表明种群间已经按地理位置形成了一定的地理格局, AMOVA分析显示北方组和南方组之间已经具有明显的遗传分化（FST=0.478, P<0.001）。综合分析, 我们认为北方组和南方组之间的遗传分化可能与差异巨大的生态条件有关。研究结果为银杏大蚕蛾的种群遗传学和生态学研究提供了一个基本的分子生物学线索。     

基于Maxent的大洋臀纹粉蚧和南洋臀纹粉蚧在中国的适生区分析

大洋臀纹粉蚧Planococcus minor Maskell和南洋臀纹粉蚧P.lilacinus Cockerell是我国有重要检疫意义的有害生物。这两种粉蚧从东盟进口水果口岸检疫中频繁截获,且已在广东、海南、云南等地发现大洋臀纹粉蚧入侵,这对我国热带、亚热带的水果和观赏植物等已构成严重威胁。本研究以大洋臀纹粉蚧和南洋臀纹粉蚧在国内外的分布数据为基础,利用Maxent生态位模型和Arc GIS对两种粉蚧在中国的潜在适生区进行预测。预测结果表明,大洋臀纹粉蚧和南洋臀纹粉蚧的适生区主要分布在长江流域以南地区,其适生区面积分别占全国面积的22.14%、18.17%,其中高度适生区域集中分布在广西、广东、云南、福建、四川、台湾、海南等地区,与我国热带水果的主要种植区域具有高度的一致性。大洋臀纹粉蚧已成功入侵,一旦南洋臀纹粉蚧传入便可迅速扩散蔓延,并对我国热带水果生产造成严重危害。因此,各口岸应加强对东盟进口水果的检验检疫,预防其新的进入和扩散。     

Adaptive basis of geographic variation: genetic,phenotypic and environmental differences among beach mouse populations

A major goal in evolutionary biology is to understand how and why populations differentiate, both genetically and phenotypically, as they invade a novel habitat. A classical example of adaptation is the pale colour of beach mice, relative to their dark mainland ancestors, which colonized the isolated sandy dunes and barrier islands on Florida''s Gulf Coast. However, much less is known about differentiation among the Gulf Coast beach mice, which comprise five subspecies linearly arrayed on Florida''s shoreline. Here, we test the role of selection in maintaining variation among these beach mouse subspecies at multiple levels—phenotype, genotype and the environments they inhabit. While all beach subspecies have light pelage, they differ significantly in colour pattern. These subspecies are also genetically distinct: pair-wise F_st-values range from 0.23 to 0.63 and levels of gene flow are low. However, we did not find a correlation between phenotypic and genetic distance. Instead, we find a significant association between the average ‘lightness’ of each subspecies and the brightness of the substrate it inhabits: the two most genetically divergent subspecies occupy the most similar habitats and have converged on phenotype, whereas the most genetically similar subspecies occupy the most different environments and have divergent phenotypes. Moreover, allelic variation at the pigmentation gene, Mc1r, is statistically correlated with these colour differences but not with variation at other genetic loci. Together, these results suggest that natural selection for camouflage—via changes in Mc1r allele frequency—contributes to pigment differentiation among beach mouse subspecies.     

中国食品源氮消费环境排放及其城乡差异

食品源氮消费是人居环境养分流动的重要环节,中国食品源氮消费产生的环境排放受城乡二元结构影响在时空变化上呈现显著分异。基于物质流分析方法,从中国城乡食品消费后产物不同处理过程及其对氮代谢的影响出发,模拟氮物质代谢过程,构建了一套氮素环境排放计算模型,借以研究中国近20年来城乡食品源氮消费环境排放趋势变化及其差异。研究结果发现1993—2012年间,我国城乡居民人均食品源氮排变化轨迹迥异。同时,城乡食品源氮消费在其所造成的水体、土壤、大气环境负荷中扮演的角色各不相同:在水体环境负荷中,农村水体氮排占据主导地位,但城乡间差异正逐步缩小;在土壤环境负荷中,城市土壤氮排主导优势明显;2010年以前全国食品源氮消费大气环境负荷主要受农村气体氮排的影响,而2010年以后,城市大气氮排成为影响全国大气氮负荷的主导因素。引入社会经济因素分析后发现,城镇居民人均可支配收入水平对城镇居民人均食品源氮排起显著促进作用;而农村食品价格指数对农村居民人均食品源环境氮排呈显著抑制作用。通过情景预测分析发现:随着我国城镇化进程的加快,未来全国居民人均食品源氮排将以更快速度继续增长。     

西部资源型城市生态安全评价与对策——以铜川市为例

随着社会经济的持续高速增长,生态安全问题也日益突出,对于我国西部干旱半干旱区的资源型城市,生态安全问题更为严峻。本文以陕西省铜川市为研究区域,运用层次分析法,基于自然环境系统、人文社会压力和环境污染压力3个综合指标层建立评价体系,对铜川市生态安全进行定量的评价和分析。结果表明,铜川市生态安全值由1997年的0.5397上升到2002年的0.5541,生态安全有所好转,但处于较差状态;自然环境和人文社会对环境的压力减少,但环境污染压力上升。最后提出铜川市生态安全的对策:改变生产方式,发展循环经济;减轻污染负荷,借鉴先进经验;合理利用水资源,实施生态工程;加强政府干预力度,建立预警机制;提高人们的生态安全意识。     

基于线粒体COI、Cytb和COII基因的中国草地螟不同地理种群遗传分化分析

【目的】揭示中国草地螟Loxostege sticticalis不同地理种群的遗传分化程度。【方法】采用PCR技术扩增中国西北和华北地区草地螟11个地理种群的线粒体 COI, Cytb和COII基因序列,基于其序列变异及单倍型贝叶斯系统发育树和单倍型网络图分析,探讨不同地理种群间的遗传距离、分子系统发生关系及遗传分化程度。【结果】草地螟11个地理种群的线粒体 COI, Cytb和COII基因序列分别有24, 12和69个变异位点(分别占总序列的3.6%, 2.7%和8.8%),检测到的单倍型分别为22, 14和16个,单倍型多样度(Hd)分别为0.7600, 0.5842和0.7341,核苷酸平均差异度(K)分别为1.704, 0.752和3.997,不同单倍型间的遗传距离平均值分别为0.004, 0.005和0.013。总种群的Tajima’s D和Fu’s Fs值皆不显著,表明草地螟不同地理种群间的遗传分化不明显,群体大小稳定。根据各地理种群的单倍型建立的系统发育树和单倍型网络图表明,各单倍型散布在不同的地理种群中,无明显的地理分布格局。【结论】草地螟各地理种群的遗传距离与地理距离间不具有显著的相关性,其遗传分化不明显。     

Fluoroquinolone resistance in Helicobacter pylori: role of mutations at position 87 and 91 of GyrA on the level of resistance and identification of a resistance conferring mutation in GyrB

Background and Aims: Fluoroquinolone‐containing regimens have been suggested as an alternate to standard triple therapy for the treatment of Helicobacter pylori infections. To determine the relationship between fluoroquinolone resistance and mutations of GyrA and GyrB in H. pylori, we exchanged the mutations at positions 87and 91 of GyrA among fluoroquinolone‐resistant clinical isolates. GyrB of a strain with no mutations in GyrA was also analyzed to identify mechanisms of resistance to norfloxacin. Materials & Methods: Natural transformation was performed using the amplified fragment of the gyrA and gyrB gene as donor DNA. The amino acid sequences of GyrA and GyrB were determined by DNA sequencing of the gyrA and gyrB genes. Results: Norfloxacin‐resistant strains which had mutations at position 87 and 91 became susceptible when the mutations were converted to the wild type. When the mutation from Asp to Asn at position 91 was exchanged to the mutation from Asn to Lys at position 87, the MIC to levofloxacin, gatifloxacin, and sitafloxacin increased. Norfloxacin‐resistant strain TS132 with no mutations in GyrA but had a mutation at position 463 in GyrB. Transformants obtained by natural transformation using gyrB DNA of TS132 had a mutation at position 463 of GyrB and revealed resistant to norfloxacin and levofloxacin. Conclusion: Mutation from Asn to Lys at position 87 of GyrA confers higher resistance to levofloxacin and gatifloxacin than does mutation from Asp to Asn at position 91. We propose that mutation at position 463 in GyrB as a novel mechanism of fluoroquinolone resistance in H. pylori.     

人口城市化与土地城市化质量耦合协调性的时空特征——以甘肃省12个中心城市为例

根据系统科学理论,在科学界定人口城市化和土地城市化内涵的基础上,以甘肃省12个中心城市为例,分别构建了人口城市化和土地城市化质量的评价指标体系.使用耦合协调模型,从时间和空间两个维度对2005—2013年甘肃省人口城市化和土地城市化质量的综合发展指数以及耦合协调度进行测算.结果表明:人口城市化和土地城市化只能反映城市化进程的快慢,并不能衡量城市化发展的质量,单一的指标只能代表狭义的城市化发展水平.从时间序列来看,甘肃省土地和人口的城市化质量以及耦合协调水平呈现整体上升态势.总的来说,土地资源集约利用程度低仍是制约甘肃省城市化质量的关键因素.从空间格局来看,2013年,除兰州属于人口城市化质量滞后型,其他11个中心城市的土地城市化质量均不同程度地滞后于人口城市化质量.甘肃省12个中心城市的城市化质量整体上处于较低水平的协调阶段.     

Arms races between social parasites and their hosts: geographic patterns of manipulation and resistance

The evolutionary interactions between permanently social parasiticspecies and their hosts are of special interest because socialparasites are not only closely dependent on, but are also closelyrelated to, their hosts. The small European slavemaker Harpagoxenussublaevis has evolved several characters that help manipulateits host. In this study we investigated adaptations of thissocial parasite to its local hosts and the geographic patternof host resistance in two main host species from three differentpopulations. In behavioral experiments, we examined whetherhost colonies from three geographically distant Leptothoraxacervorum populations varied in their ability to defend thenest against social parasites. Naive colonies from the unparasitizedEnglish population killed attacking slavemakers more often thandid host colonies from two parasitized populations. We alsofound strong interpopulation variation in the ability of theslavemaker to manipulate host behavior. H. sublaevis uses theDufour gland secretion to induce intracolonial fights and, ingeneral, this "propaganda" substance was most effective againstlocal hosts. Our results suggest that the social parasite isleading the arms race in this aspect. Similar experiments uncovereddifferences between two populations of the second host speciesL. muscorum and could demonstrate that nest defense in bothhost species is similarly efficient. In L. acervorum, monogynouscolonies were more successful in nest defense, whereas socialstructure had no impact in L. muscorum. Colony size did notaffect the efficacy of nest defense in either host species.The caste of the slavemaker had a strong influence on the successof an attack.     

中国蚂蚁丰富度地理分布格局及其与环境因子的关系

物种丰富度分布格局及其形成机制的研究对于生物多样性保护具有重要意义。为了了解中国蚂蚁物种丰富度分布格局,利用中国省级尺度蚂蚁物种分布数据和环境信息,结合GIS和数理统计方法,探讨蚂蚁物种丰富度的地理分布格局与环境因子之间的关系。研究结果表明:(1)蚂蚁丰富度随纬度增加呈逐渐递减趋势,但缺乏显著的经度梯度。丰富度最高的地区主要集中在南方省份,我国北方、西北干旱区和青藏高原北部地区丰富度较低;(2)简单线性回归分析表明,能量、水分和季节性因素中,影响蚂蚁物种丰富度最强的因子分别为最冷月均温(TEMmin)(R2adj=0.532)、年均降水量(PREC)(R2adj=0.376)和年温度变化范围(TEMvar)(R2adj=0.539),而单个生境异质性因子对蚂蚁物种丰富度的影响均不显著;(3)最优模型由年均温(TEM)、海拔变化范围(ELErange)和年温度变化范围(TEMvar)组成,能够解释68.4%的蚂蚁丰富度地理分异。鉴于海拔变化范围更多地反映与温度相关的生境异质性,因此温度是限制中国蚂蚁分布的最重要因素。另外,分析结果还表明,海南、贵州、江西、四川、安徽和山西等6省蚂蚁区系调查最不充分,是未来发现蚂蚁新分布的热点地区。     

中国甜菜夜蛾地理种群的遗传分化与基因流

【目的】为了明确我国甜菜夜蛾Spodoptera exigua地理种群间的遗传分化及基因流,阐明该种害虫在我国的种群历史动态。【方法】本研究对采自我国20个地理种群的529头甜菜夜蛾样品进行线粒体COI基因序列测定与分析,利用DnaSP 5.0和Arlequin 3.11软件分析种群间遗传多样性、遗传分化、基因流水平及分子变异,构建了单倍型系统发育树与单倍型网络图。【结果】在所分析的所有529个序列样本中,共检测出10个单倍型,其中Hap_1为所有种群所共享。总群体遗传多样性较低（Hd=0.257±0.025,Pi=0.0007±0.0001,Kxy=0.323）,群体间遗传分化较小（F_ST=0.211）,基因流水平较高（N_m=1.870）。AMOVA分析表明,甜菜夜蛾遗传变异主要来自种群内,种群间变异水平较低。各种群间遗传分化程度与地理距离无显著相关性（R²=0.005,P>0.05）。各单倍型相互散布在不同种群中,未形成明显系统地理结构。中性检验（Tajima’s D=-2.177, P<0.05; Fu’s F_S=-8.629, P<0.05)与错配分布分析表明,我国甜菜夜蛾种群曾经历种群近期扩张。【结论】研究结果揭示,甜菜夜蛾各种群间的基因交流并未受到地理距离的影响,验证了甜菜夜蛾具有高度的迁飞能力。     

武陵山片区城镇化与生态环境耦合协调度时空分异——以六个中心城市为例

城镇化与生态环境之间是相互联系和促进的唇齿关系,其耦合协调程度对实现地区高质量发展和可持续发展具有重大影响。将物理学中的"耦合"概念引入城镇化与生态环境耦合协调研究中,建立了耦合协调度模型,并构建了城镇化与生态环境耦合协调度评价指标体系和耦合协调度基本类型划分体系,分析了2010-2018年武陵山片区六个中心城市城镇化与生态环境耦合协调度的时空分异。结果表明：（1）各中心城市的耦合协调基础较好,且呈现出良好的发展态势。（2）各中心城市的空间差异明显,2010年、2015年与2018年六个中心城市城镇化与生态环境耦合协调发展内部差异性较大,东部大于西部,怀化市"单核"特征明显。（3）武陵山片区城镇化与生态环境耦合协调度没有实现突破性、跨越式的提升,且城镇化滞后的问题较为明显,影响了两者实现高耦合协调度的进程。研究认为须要坚持以绿色为底色,以生态为引领,加快提升武陵山片区城镇化发展水平,走出一条绿色生态的城镇化高质量发展新路。     

土地经济生态位在县域景观格局分析中的应用——以新疆精河县为例

本文将土地经济生态位的理论和方法引入到景观生态学当中,为区域景观格局表征提供了新的方法.选择典型的生态脆弱区精河县为研究对象,以1990、1998、2011和2013年4期Landsat影像为数据源,运用生态位态势理论计算研究区各土地利用类型的土地经济生态位,并结合景观生态学理论探讨土地经济生态位在县域景观格局分析中的应用.结果表明: 研究期间,精河县耕地、建设用地和草地的土地经济生态位与相应的景观斑块数、聚合度、破碎化指数和分维数具有较好的相关性;土地经济生态位的变化对县域景观格局具有驱动作用,可表征精河县经济发展方向.土地经济生态位与可直接获得经济效益的土地利用类型关系密切,且与景观指数相结合能够很好地解释精河县景观格局的特征.     

Assessments of contamination and human health risks of heavy metals in the road dust from a mining county in Guangxi,China

A total of 32 road dust samples were collected from mining areas and a control area in Nandan County, Guangxi, in order to investigate the contamination characteristics of heavy metals and associated health risks to local residents. The results indicated that elevated concentrations of As, Cd, Cu, Pb, Sb, and Zn were found in road dust in mining areas compared with control areas and background values. Pearson's correlation analysis and principal component analysis indicated that As, Cd, Cu, Pb, Sb, and Zn in road dust mainly originated from anthropogenic sources (e.g., vehicles emission, mining activities, and smelting activities), whereas Cr, Co, and Ni were associated with natural sources (e.g., soil weathering). Furthermore, noncarcinogenic hazards to both adults and children were found in mining areas, while noncarcinogenic health risks in the control area were negligible. The health hazard was mostly ascribed to the ingestion, followed by the dermal contact, and the inhalation. The cancer risks from As, Cd, Co, Cr, and Ni in all studied areas were within safe levels as the R values were below the threshold of 1 × 10^?6.     

Epigenome-wide profiling identifies significant differences in DNA methylation between matched-pairs of T- and B-lymphocytes from healthy individuals

Multiple reports now describe changes to the DNA methylome in rheumatoid arthritis and in many cases have analyzed methylation in mixed cell populations from whole blood. However, these approaches may preclude the identification of cell type-specific methylation, which may subsequently bias identification of disease-specific changes. To address this possibility, we conducted genome-wide DNA methylation profiling using HumanMethylation450 BeadChips to identify differences within matched pairs of T-lymphocytes and B-lymphocytes isolated from the peripheral blood of 10 healthy females. Array data were processed and differential methylation identified using NIMBL software. Validation of array data was performed by bisulfite pyrosequencing. Genome-wide DNA methylation was initially determined by analysis of LINE-1 sequences and was higher in B-lymphocytes than matched T-lymphocytes (69.8% vs. 65.2%, P ≤ 0.01). Pairwise analysis identified 679 CpGs, representing 250 genes, which were differentially methylated between T-lymphocytes and B-lymphocytes. The majority of sites (76.6%) were hypermethylated in B-lymphocytes. Pyrosequencing of selected candidates confirmed the array data in all cases. Hierarchical clustering revealed perfect segregation of samples into two distinct clusters based on cell type. Differentially methylated genes showed enrichment for biological functions/pathways associated with leukocytes and T-lymphocytes. Our work for the first time shows that T-lymphocytes and B-lymphocytes possess intrinsic differences in DNA methylation within a restricted set of functionally related genes. These data provide a foundation for investigating DNA methylation in diseases in which these cell types play important and distinct roles.