BACKGROUND & AIMS: OBJECTIVE:To investigate the simultaneous occurrence of more than 1 Clostridium difficile ribotype in patients' stool samples at the time of diagnostic testing. METHODS:Stool samples submitted for diagnostic testing for the presence of toxigenic C. difficile were obtained for 102 unique patients. A total of 95 single colonies of C. difficile per stool sample were isolated on selective media, subcultured alongside negative (uninoculated) controls, and polymerase chain reaction (PCR) ribotyped using capillary gel electrophoresis. RESULTS:Capillary-based PCR ribotyping was successful for 9,335 C. difficile isolates, yielding a median of 93 characterized isolates per stool sample (range, 69-95). More than 1 C. difficile ribotype was present in 16 of 102 (16%) C. difficile infection (CDI) cases; 2 of the 16 mixtures were composed of at least 3 ribotypes, while the remaining 14 were composed of at least 2. CONCLUSIONS:Deep sampling of patient stool samples coupled with capillary-based PCR ribotyping identified a high rate of mixed CDI cases compared with previous estimates. Studies seeking to quantify the clinical significance of particular C. difficile ribotypes should account for mixed cases of disease.

背景与目标：

BACKGROUND & AIMS: :Nonradioactive sequence-specific oligonucleotide (SSO) probes specific for the HLA-DP beta locus have been used in a simple dot-blot assay to DP beta-type samples amplified by the polymerase chain reaction (pcr) from Caucasoid (n = 24) and Japanese (n = 23) patients with multiple sclerosis (ms) as well as ethnically matched controls. In contrast to previous reports, no DP beta allele was found to be increased in either patient population. However, the results do show a dramatic difference in the allele frequencies between the two control populations, further emphasizing the need for ethnically matched controls in studies of HLA and disease.

背景与目标： : 对hla-dp β 基因座特异的非放射性序列特异性寡核苷酸 (SSO) 探针已用于简单的斑点印迹分析，通过聚合酶链反应 (pcr) 从高加索人 (n = 24) 扩增的DP β 型样品) 和日本 (n = 23) 多发性硬化症患者 (ms) 以及种族匹配的对照。与以前的报告相反，在两种患者人群中均未发现DP β 等位基因增加。然而，结果确实显示了两个对照人群之间等位基因频率的显着差异，进一步强调了在HLA和疾病研究中需要种族匹配的对照。

BACKGROUND & AIMS: :We developed bulked segregant analysis as a method for rapidly identifying markers linked to any specific gene or genomic region. Two bulked DNA samples are generated from a segregating population from a single cross. Each pool, or bulk, contains individuals that are identical for a particular trait or genomic region but arbitrary at all unlinked regions. The two bulks are therefore genetically dissimilar in the selected region but seemingly heterozygous at all other regions. The two bulks can be made for any genomic region and from any segregating population. The bulks are screened for differences using restriction fragment length polymorphism probes or random amplified polymorphic DNA primers. We have used bulked segregant analysis to identify three random amplified polymorphic DNA markers in lettuce linked to a gene for resistance to downy mildew. We showed that markers can be reliably identified in a 25-centimorgan window on either side of the targeted locus. Bulked segregant analysis has several advantages over the use of near-isogenic lines to identify markers in specific regions of the genome. Genetic walking will be possible by multiple rounds of bulked segregation analysis; each new pair of bulks will differ at a locus identified in the previous round of analysis. This approach will have widespread application both in those species where selfing is possible and in those that are obligatorily outbreeding.

背景与目标： : 我们开发了大量的分离物分析，作为一种快速识别与任何特定基因或基因组区域相关的标记的方法。从单个杂交的分离种群中产生两个大量的DNA样本。每个池或整体包含对于特定性状或基因组区域相同但在所有未连接区域任意的个体。因此，这两个大块在选定区域在遗传上是不同的，但在所有其他区域似乎是杂合的。这两个大块可以用于任何基因组区域和任何分离的种群。使用限制性片段长度多态性探针或随机扩增的多态性DNA引物筛选大块的差异。我们已经使用大量的分离物分析来鉴定生菜中的三个随机扩增的多态性DNA标记，这些标记与抗霜霉病的基因相关。我们表明，可以在目标基因座两侧的25厘摩根窗口中可靠地识别出标记。与使用近等基因系鉴定基因组特定区域中的标记相比，大量分离物分析具有多个优势。通过多轮膨胀的分离分析，遗传行走是可能的; 每对新的大块在上一轮分析中确定的基因座上会有所不同。这种方法将在可能自交的物种和强制近交的物种中得到广泛应用。

BACKGROUND & AIMS: :A cross-sectional survey was conducted of sexually transmitted diseases (STDs) and risky behaviors among 407 drug abusers in treatment facilities in 1998. Infections with human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), herpes simplex virus type 2 (HSV-2), and syphilis were detected by testing serum antibody levels; chlamydia and gonorrhea were detected by testing nucleic acid levels in urine. Logistic regression analysis was performed to measure associations. Prevalences of antibodies were as follows: to HSV-2, 44.4%; to HCV, 35.1%; to HBV, 29.5%; to HIV, 2.7%. The prevalence of syphilis was 3.4%; of chlamydia, 3.7%; and of gonorrhea, 1.7%. Of the 407 subjects, approximately 62% had markers for 1 of the STDs. HIV infection was associated with African American race, use of smokable freebase (crack) cocaine, and STD history. HBV infection was associated with age >30 years, injecting drugs, needle sharing, a history of treatment for drug abuse, and African American race. HCV infection was associated with an age >30 years, injecting drugs, and needle sharing, and HSV-2 infection with an age >30 years, female sex, and African American race. Syphilis was associated with a history of STDs. High prevalences of STDs among drug abusers indicate the need for integration of STD screening and treatment into drug treatment programs.

背景与目标： : 对1998年治疗机构中的407名吸毒者进行了性传播疾病 (std) 和危险行为的横断面调查。检测血清抗体水平，检测人类免疫缺陷病毒 (HIV) 、乙型肝炎病毒 (HBV) 、丙型肝炎病毒 (HCV) 、单纯疱疹病毒2型 (HSV-2) 、梅毒感染; 检测尿液中核酸水平，检测衣原体和淋病。进行Logistic回归分析以测量关联。抗体的患病率如下: HSV-2，44.4%; HCV，35.1%; HBV，29.5%; HIV，2.7%。梅毒的患病率为3.4%; 衣原体，3.7%; 淋病，1.7%。在407名受试者中，大约62% 名具有1个性病的标志物。HIV感染与非裔美国人种族，使用可吸烟的免费可卡因 (快克) 和性病史有关。HBV感染与年龄> 30岁，注射药物，共用针头，药物滥用治疗史和非裔美国人有关。HCV感染与年龄> 30岁，注射毒品和共用针头有关，HSV-2感染与年龄> 30岁，女性和非裔美国人有关。梅毒与性病史有关。吸毒者中性病的患病率很高，这表明需要将性病筛查和治疗纳入药物治疗计划。

BACKGROUND & AIMS: :This investigation examined differences in symptom patterns of two different trauma samples using the Minnesota Multiphasic Personality Inventory-2 (MMPI-2). MMPI-2s of 122 male combat veterans seeking outpatient treatment for combat-related PTSD were compared with those of 64 PTSD-diagnosed adults seeking outpatient treatment for the effects of child sexual abuse (CSA). We examined variables related to degree of health concerns, depression, somatization, anger and hostility, masculine-feminine traits, paranoid ideation, anxiety, difficulties thinking and concentrating, elevated mood, and social introversion, as well as test-taking attitude. MANOVAs revealed between-group differences on several variables. However, when analyses controlled for the effect of age, nearly all differences disappeared; the only remaining difference was in a scale measuring anger. Thus, it appears CSA survivors and combat veterans are much more similar than different in their clinical presentation on the MMPI-2. Conceptual issues in the assessment of PTSD are discussed.

背景与目标： : 这项调查使用明尼苏达州多相人格量表-2 (MMPI-2) 检查了两种不同创伤样本的症状模式差异。将122名寻求与战斗相关的PTSD进行门诊治疗的男性战斗退伍军人的MMPI-2s与64名经PTSD诊断为儿童性虐待 (CSA) 的门诊治疗的成年人进行了比较。我们研究了与健康问题程度，抑郁，躯体化，愤怒和敌意，男性女性特征，偏执观念，焦虑，思考和集中注意力的困难，情绪低落，社交内向以及应试态度有关的变量。MANOVAs揭示了几个变量的组间差异。但是，当分析控制了年龄的影响时，几乎所有差异都消失了。唯一剩下的差异是衡量愤怒的量表。因此，看来CSA幸存者和战斗退伍军人在MMPI-2上的临床表现要相似得多。讨论了PTSD评估中的概念问题。

BACKGROUND & AIMS: :Tungiasis (sand flea disease) is an ectoparasitic skin disease caused by the female sand flea/jigger flea (Tunga penetrans). As poverty is the major driving force of the disease, it can be called as a poverty-associated plague. It is one of the emerging neglected diseases in Latin America, Caribbean, sub-Saharan Africa, and India. The aim of the present scrutiny was to assess the public health impact of tungiasis, associated risk factors, and emerging opportunities to prevent and control tungiasis. Searches of PubMed, Google Scholar, and online search engines (Google, AOL, and Yahoo) using keywords "parasitic skin disease," "tungiasis," "sand flea," " tungiasis-associated risk factors," "tungiasis prevention and control," and their synonyms were used as a source of references. Searches were made without time limitations. Of 167 potential articles identified by these criteria, 51 appropriate were selected for review. Tungiasis is widespread in the resource-constrained settings of low-income economies. In the tropics, it is highly prevalent among the impoverished populations, but the associated risk factors are often poorly identified and remain uncontrolled. Though it is a self-limiting disease with considerable morbidity, the parasite may cause subsequent secondary morbidity through life-threatening complications and infections like cellulitis, tetanus, and death. However, the direct and indirect sociocultural, economic, and health impact of tungiasis is often undervalued and misunderstood. A systematic assessment on disease burden is still dearth and deficient. Over the decades, tungiasis has been largely neglected by the scientific community, policy makers, and healthcare stakeholders. In the endemic regions, even tungiasis is not listed for the disease control priorities in the regional, national, and international agenda. The majority of the epidermal parasitic skin diseases particularly tungiasis needs a sustainable global scientific research and control policy. This urges intensive efforts to develop a road map that delivers a clear vision towards zero new infection by designing low-cost prevention and control strategies. Besides, there is an urgency to develop culturally appropriate communication techniques and workable collaboration on a global scale by bringing all the stakeholders of endemic countries.

背景与目标： : Tungiasis (沙蚤病) 是由雌性沙蚤/跳蚤 (Tunga penetrans) 引起的一种外部寄生虫性皮肤病。由于贫困是该疾病的主要驱动力，因此可以将其称为与贫困相关的瘟疫。它是拉丁美洲，加勒比海地区，撒哈拉以南非洲和印度新兴的被忽视的疾病之一。本次审查的目的是评估外膜病对公共卫生的影响，相关的危险因素以及预防和控制外膜病的新兴机会。搜索PubMed，Google Scholar和在线搜索引擎 (Google，AOL和Yahoo)，使用关键字 “寄生性皮肤病”，“tungiasis”，“沙蚤”，“tungiasis相关危险因素”，“tungiasis预防和控制，” 和它们的同义词被用作参考文献的来源。搜索没有时间限制。在这些标准确定的167篇潜在文章中，选择了51篇合适的文章进行审查。在低收入经济体资源受限的环境中，突尼斯病很普遍。在热带地区，它在贫困人口中非常普遍，但相关的风险因素往往无法识别，并且仍然不受控制。尽管它是一种具有相当高发病率的自限性疾病，但该寄生虫可能会通过威胁生命的并发症和感染 (如蜂窝织炎，破伤风和死亡) 引起继发疾病。但是，tungiasis对社会文化，经济和健康的直接和间接影响常常被低估和误解。对疾病负担的系统评估仍然缺乏和不足。几十年来，tungiasis在很大程度上被科学界，政策制定者和医疗保健利益相关者所忽视。在流行地区，甚至在区域，国家和国际议程中也没有将tungiasis列为疾病控制重点。大多数表皮寄生性皮肤病，尤其是tungiasis，需要可持续的全球科学研究和控制政策。这敦促加紧努力，制定路线图，通过设计低成本的预防和控制策略，实现零新感染的清晰愿景。此外，迫切需要通过吸引流行国家的所有利益攸关方，在全球范围内发展文化上适当的交流技术和可行的合作。

BACKGROUND & AIMS: A genetic analysis realized, on Tunisian coasts, within and between two populations of a Teleostean (Sardina pilchardus) on one hand, and two populations of their parasitic Copepods (Peroderma cylindricum) on the other hand, reveal that(l) the 14 loci analysed are monomorphic in the Teleostean populations; (II) 3 loci among 13 investigated are polymorphic in the Copepod populations. Statistical tests from deviations of Hardy-Weinberg equilibrium and genotypic homogeneity show the existence of strong gene flows within and between Copepod populations. Thus, it seems that the Teleostean (Sardina pilchardus) and the Copepod (Peroderma cylindricum) constitute at least on Tunisian coasts, two homogeneous taxinomic units.

背景与目标： 在突尼斯沿海地区，一方面在两个硬骨种群 (Sardina pilchardus) 和两个寄生co足类种群 (Peroderma cylindricum) 之间和之间进行的遗传分析表明 (l) 所分析的14个基因座在硬骨种群中是单形的; (II) 在被调查的13个基因座中，有3个基因座在co足类种群中具有多态性。从Hardy-Weinberg平衡和基因型同质性的偏差进行的统计测试表明，co足类种群内部和之间存在强烈的基因流。因此，似乎Teleostean (Sardina pilchardus) 和co足类 (Peroderma cylindriicum) 至少在突尼斯海岸上构成了两个同质的taxinomic单位。

BACKGROUND & AIMS: :Informed consent is an essential requirement prior to clinical trial participation, however some 'vulnerable' groups, such as people with cognitive impairments and those in medical emergency situations, may lack decisional capacity to consent. This raises ethical and practical challenges when designing and conducting clinical trials involving these populations, who are frequently excluded as a result. Despite recent advances in improving informed consent processes, there has been far less attention paid to the enrolment of adults lacking capacity. Exclusion criteria are an important determinant of the external validity of clinical trial results. The exclusion of these populations, and consent-based recruitment biases which arise from the challenges of identifying and involving surrogate decision-makers, leads to trials which are not representative of the clinical population. This article discusses the involvement of adults who lack decisional capacity to consent in clinical trials and presents the advances over the previous decade and the remaining ethical challenges for the inclusion of this under-represented population in research.

背景与目标： : 知情同意是参与临床试验之前的基本要求，但是某些 “弱势” 群体，例如认知障碍患者和医疗紧急情况下的患者，可能缺乏决策同意能力。在设计和进行涉及这些人群的临床试验时，这提出了道德和实践方面的挑战，这些人群经常因此而被排除在外。尽管最近在改善知情同意程序方面取得了进展，但对缺乏能力的成年人的入学关注却少得多。排除标准是临床试验结果外部有效性的重要决定因素。这些人群被排除在外，以及由于识别和涉及替代决策者的挑战而产生的基于同意的招募偏见，导致无法代表临床人群的试验。本文讨论了缺乏决策能力的成年人参与临床试验的情况，并介绍了过去十年的进展以及将这一代表性不足的人群纳入研究的剩余伦理挑战。

BACKGROUND & AIMS: :Understanding the population genetic consequences of habitat heterogeneity requires assessing whether patterns of gene flow correspond to landscape configuration. Studies of the genetic structure of populations are still scarce for Neotropical forest birds. We assessed range-wide genetic structure and contemporary gene flow in the thorn-tailed rayadito (Aphrastura spinicauda), a passerine bird inhabiting the temperate forests of South America. We used 12 microsatellite loci to genotype 582 individuals from eight localities across a large latitudinal range (30°S-56°S). Using population structure metrics, multivariate analyses, clustering algorithms, and Bayesian methods, we found evidence for moderately low regional genetic structure and reduced gene flow towards the range margins. Genetic differentiation increased with geographic distance, particularly in the southern part of the species' distribution where forests are continuously distributed. Populations in the north seem to experience limited gene flow likely due to forest discontinuity, and may comprise a demographically independent unit. The southernmost population, on the other hand, is genetically depauperate and different from all other populations. Different analytical approaches support the presence of three to five genetic clusters. We hypothesize that the genetic structure of the species follows a hierarchical clustered pattern.

背景与目标： : 了解栖息地异质性的种群遗传后果需要评估基因流模式是否与景观配置相对应。对于新热带森林鸟类，对种群遗传结构的研究仍然很少。我们评估了栖息在南美温带森林中的雀形目鸟刺尾rayadio (Aphrastura spinicauda) 的范围内的遗传结构和当代基因流。我们使用12个微卫星基因座对大纬度范围 (30 ° S-56 ° S) 的8个地区的582个个体进行基因型。使用种群结构指标，多元分析，聚类算法和贝叶斯方法，我们发现了适度低区域遗传结构和减少向范围边缘的基因流的证据。遗传分化随着地理距离的增加而增加，尤其是在该物种分布的南部，那里的森林不断分布。北部的人口似乎经历了有限的基因流，这可能是由于森林的不连续性，并且可能是人口统计学上独立的单位。另一方面，最南端的人口在遗传上是不安全的，与所有其他人口都不同。不同的分析方法支持三到五个遗传簇的存在。我们假设该物种的遗传结构遵循分层聚类模式。

BACKGROUND & AIMS: BACKGROUND:Copy Number Variations (CNVs) are gain or loss of DNA segments that are known to play a role in shaping a wide range of phenotypes. In this study, we used two dairy cattle populations, Holstein Friesian and Jersey, to discover CNVs using the Illumina BovineHD Genotyping BeadChip aligned to the ARS-UCD1.2 assembly. The discovered CNVs were investigated for their functional impact and their population genetics features. RESULTS:We discovered 14,272 autosomal CNVs, which were aggregated into 1755 CNV regions (CNVR) from 451 animals. These CNVRs together cover 2.8% of the bovine autosomes. The assessment of the functional impact of CNVRs showed that rare CNVRs (MAF < 0.01) are more likely to overlap with genes, than common CNVRs (MAF ≥ 0.05). The Population differentiation index (Fst) based on CNVRs revealed multiple highly diverged CNVRs between the two breeds. Some of these CNVRs overlapped with candidate genes such as MGAM and ADAMTS17 genes, which are related to starch digestion and body size, respectively. Lastly, linkage disequilibrium (LD) between CNVRs and BovineHD BeadChip SNPs was generally low, close to 0, although common deletions (MAF ≥ 0.05) showed slightly higher LD (r2 = ~ 0.1 at 10 kb distance) than the rest. Nevertheless, this LD is still lower than SNP-SNP LD (r2 = ~ 0.5 at 10 kb distance). CONCLUSIONS:Our analyses showed that CNVRs detected using BovineHD BeadChip arrays are likely to be functional. This finding indicates that CNVs can potentially disrupt the function of genes and thus might alter phenotypes. Also, the population differentiation index revealed two candidate genes, MGAM and ADAMTS17, which hint at adaptive evolution between the two populations. Lastly, low CNVR-SNP LD implies that genetic variation from CNVs might not be fully captured in routine animal genetic evaluation, which relies solely on SNP markers.

背景与目标：

BACKGROUND & AIMS: :Risk assessment for nutrients assumes a single population with a normal distribution of indexes of requirements and excess. Toxic levels are by definition intakes above the upper level; for copper, however, because we lack noninvasive, sensitive biomarkers of storage or early damage from excess, excess is based on the infrequent occurrence of clinical disease, such as unexplained liver cirrhosis. We examine the limitations of this approach for copper given the very low prevalence of clinical and subclinical disease and suggest that the population risk for copper excess be based on hepatic copper loading as a potentially quantifiable measurement. The challenge ahead is to develop biomarkers that predict the population risk of elevated hepatic copper stores and thus the possibility of disease in a population.

背景与目标： : 营养素的风险评估假设单个人群的需求和过量指数呈正态分布。根据定义，毒性水平高于较高水平; 然而，对于铜，由于我们缺乏非侵入性、敏感的生物标志物储存或过量的早期损害，过量是基于临床疾病的罕见发生，如不明原因的肝硬化。鉴于临床和亚临床疾病的患病率非常低，我们研究了这种方法对铜的局限性，并建议铜过量的人群风险基于肝铜负荷作为潜在的可量化度量。未来的挑战是开发生物标志物，以预测肝铜存储升高的人群风险，从而预测人群中疾病的可能性。

BACKGROUND & AIMS: :The objective of the present study was to examine the extent of genetic diversity among Sarcoptes scabiei individuals belonging to different skin subunits of the body from individual mangy hosts. Ten microsatellite primers were applied on 44 individual S. scabiei mites from three mangy Iberian ibexes from Sierra Nevada Mountain in Spain. Dendrograms of the mites from the individual Iberian ibexes, showing the proportion of shared alleles between pairs of individual mites representing three skin subpopulations (head, back, and abdomen subunits), allowed the clustering of some mite samples up to their skin subunits. This genetic diversity of S. scabiei at skin-scale did not have the same pattern in all considered hosts: for the first Iberian ibex (Cp1), only mites from the head subunit were grouped together; in the second individual (Cp2), the clustering was detected only for mites from the abdomen subunit; and for the third one (Cp3), only mites from the back subunit were clustered together. Our results suggest that the local colonization dynamics of S. scabiei would have influenced the nonrandom distribution of this ectoparasite, after a single infestation. Another presumable explanation to this skin-scale genetic structure could be the repeated infestations. To our knowledge, this is the first documentation of genetic structuring among S. scabiei at individual host skin-scale. Further studies are warranted to highlight determining factors of such trend, but the pattern underlined in the present study should be taken into account in diagnosis and monitoring protocols for studying the population genetic structure and life cycle of this neglected but important ectoparasite.

背景与目标： : 本研究的目的是检查来自个体mangy宿主的不同皮肤亚基的Sarcoptes scabiei个体之间的遗传多样性程度。十个微卫星引物应用于来自西班牙内华达山的三个笨拙的伊比利亚山羊的44个单独的S. scabiei螨。来自各个伊比利亚ibexes的螨虫的树状图显示了代表三个皮肤亚群 (头，背和腹部亚群) 的成对的单个螨虫之间共享等位基因的比例，允许将一些螨虫样本聚集到其皮肤亚群。皮肤规模的scabiei S. scabiei的这种遗传多样性在所有考虑的宿主中都没有相同的模式: 对于第一个伊比利亚ibex (Cp1)，只有来自头部亚基的螨虫被分组在一起; 在第二个个体 (Cp2) 中，仅检测到来自腹部亚基的螨虫的聚类; 对于第三个 (Cp3)，只有来自背部亚基的螨虫聚集在一起。我们的结果表明，在一次侵扰后，S. scabiei的局部定植动态会影响该外寄生虫的非随机分布。这种皮肤规模遗传结构的另一个可推测的解释可能是反复感染。据我们所知，这是第一个在单个宿主皮肤尺度上的scabiei S. scabiei基因结构的文献。需要进一步的研究来强调这种趋势的决定因素，但是在诊断和监测方案中应考虑本研究中强调的模式，以研究这种被忽视但重要的外寄生虫的种群遗传结构和生命周期。

BACKGROUND & AIMS: :Much of the recent debate over race, genetics, and health has focused on the extent to which typological notions of race have biological meaning. Less attention, however, has been paid to the assumptions about the nature of "populations" that both inform contemporary biological and medical research and that underlie the concept of race. Focusing specifically on Africa in the 1930s and 1940s, this paper explores the history of how fluid societies were transformed into bounded units amenable to scientific analysis. In the so-called "Golden Age of Ethnography," university-trained social anthropologists, primarily from Britain and South Africa, took to the field to systematically study, organize, and order the world's diverse peoples. Intent on creating a scientific methodology of neutral observation, they replaced amateur travelers, traders, colonial administrators, and missionaries as authoritative knowledge producers about the customs, beliefs, and languages of indigenous peoples. At the same time, linguists were engaged in unifying African languages and mapping language onto primordial "tribal" territories. We argue that the notion of populations or "tribes" as discrete units suitable for scientific sampling and classification emerged in the 1930s and 1940s with the ethnographic turn in social anthropology and the professionalization and institutionalization of linguistics in Western and South African universities. Once named and entered into international atlases and databases by anthropologists in the U.S., the existence of populations as bounded entities became self-evident, thus setting the stage for their use in large-scale population genetic studies and the contemporary reinvigoration of broad claims of difference based on population identification.

背景与目标： : 最近关于种族，遗传学和健康的许多辩论都集中在种族类型学概念在多大程度上具有生物学意义。然而，人们对 “人口” 性质的假设的关注较少，这些假设既为当代生物学和医学研究提供了信息，又为种族概念奠定了基础。本文特别关注20世纪30年代和20世纪40年代的非洲，探讨了流动社会如何转变为适合科学分析的有限单位的历史。在所谓的 “民族志的黄金时代” 中，主要来自英国和南非的受过大学训练的社会人类学家进入该领域，系统地研究，组织和秩序世界上的各个民族。为了建立一种科学的中立观察方法，他们取代了业余旅行者，商人，殖民地管理者和传教士，成为有关土著人民习俗，信仰和语言的权威知识生产者。同时，语言学家致力于统一非洲语言并将语言映射到原始的 “部落” 领土上。我们认为，人口或 “部落” 作为适合科学采样和分类的离散单位的概念出现在20世纪30年代中，并与社会人类学的人种学转向以及西方和南非大学语言学的专业化和制度化20世纪40年代。一旦被美国人类学家命名并进入国际地图集和数据库，种群作为有界实体的存在就变得不言而喻了，从而为它们在大规模种群遗传研究中的使用奠定了基础，并在当代重振了广泛的主张基于种群识别的差异。

BACKGROUND & AIMS: :The development of methodology to differentiate mixed populations of Escherichia coli in the secondary habitat might improve monitoring of fecal pollution indicators and facilitate the development of strategies to mitigate bacterial pollution. The objective of this study was to determine the ability of denaturing gradient gel electrophoresis (DGGE) to differentiate mixed assemblages of E. coli in the natural environment. After confirming the identity of 184 environmental bacterial isolates as E. coli, each was subjected to polymerase chain reaction (PCR) of the beta-glucuronidase gene (uidA) followed by DGGE fingerprinting. The ability of DGGE to discriminate individual isolates at the strain level was determined by comparing fingerprints to those resulting from a standard, library-dependent fingerprinting method, BOX-PCR. Computerized analysis of fingerprints indicated that DGGE and BOX-PCR identified 15 and 21 unique phylotypes respectively. Rank-abundance plots comparing the numerical distribution of unique E. coli phylotypes detected by both methods revealed no difference in resolution at the population level. In water and sediment samples from two beaches, DGGE effectively distinguished indigenous E. coli populations with an average rate of correct classification (site-based) of 83%. Denaturing gradient gel electrophoresis of uidA genes isolated and PCR-amplified from environmental samples appears to be an effective tool to differentiate unique E. coli populations and should be useful to characterize E. coli dynamics in the secondary environment.

背景与目标： : 开发区分次级生境中大肠杆菌混合种群的方法可能会改善对粪便污染指标的监测，并促进减轻细菌污染的策略的制定。这项研究的目的是确定变性梯度凝胶电泳 (DGGE) 在自然环境中区分大肠杆菌混合组合的能力。在确认184环境细菌分离株作为大肠杆菌的身份之后，对每个细菌进行 β-葡萄糖醛酸苷酶基因 (uidA) 的聚合酶链反应 (PCR)，然后进行DGGE指纹图谱。通过将指纹与标准的，依赖文库的指纹图谱方法BOX-PCR产生的指纹进行比较，确定了DGGE在菌株水平上区分单个分离株的能力。指纹的计算机分析表明，DGGE和BOX-PCR分别鉴定出15和21种独特的系统类型。比较通过两种方法检测到的独特大肠杆菌系统型的数值分布的等级丰度图显示，在种群水平上的分辨率没有差异。在来自两个海滩的水和沉积物样本中，DGGE有效地区分了本地大肠杆菌种群，其平均正确分类率 (基于站点) 为83%。从环境样品中分离和PCR扩增的uidA基因的变性梯度凝胶电泳似乎是区分独特的大肠杆菌种群的有效工具，并且对于表征次级环境中的大肠杆菌动力学应该有用。

BACKGROUND & AIMS: :Usually, genetic correlations are estimated from breeding designs in the laboratory or greenhouse. However, estimates of the genetic correlation for natural populations are lacking, mostly because pedigrees of wild individuals are rarely known. Recently Lynch (1999) proposed a formula to estimate the genetic correlation in the absence of data on pedigree. This method has been shown to be particularly accurate provided a large sample size and a minimum (20%) proportion of relatives. Lynch (1999) proposed the use of the bootstrap to estimate standard errors associated with genetic correlations, but did not test the reliability of such a method. We tested the bootstrap and showed the jackknife can provide valid estimates of the genetic correlation calculated with the Lynch formula. The occurrence of undefined estimates, combined with the high number of replicates involved in the bootstrap, means there is a high probability of obtaining a biased upward, incomplete bootstrap, even when there is a high fraction of related pairs in a sample. It is easier to obtain complete jackknife estimates for which all the pseudovalues have been defined. We therefore recommend the use of the jackknife to estimate the genetic correlation with the Lynch formula. Provided data can be collected for more than two individuals at each location, we propose a group sampling method that produces low standard errors associated with the jackknife, even when there is a low fraction of relatives in a sample.

背景与目标： : 通常，遗传相关性是根据实验室或温室中的育种设计估算的。但是，缺乏对自然种群遗传相关性的估计，主要是因为很少知道野生个体的谱系。最近，Lynch (1999) 提出了一个公式来估计在没有有关谱系数据的情况下的遗传相关性。该方法已被证明在大样本量和最小 (20%) 亲属比例的情况下特别准确。Lynch (1999) 提出使用bootstrap来估计与遗传相关性相关的标准误差，但未测试这种方法的可靠性。我们测试了bootstrap，并证明了折刀可以提供用Lynch公式计算的遗传相关性的有效估计。未定义的估计的出现，再加上引导程序中涉及的大量重复，意味着即使在样本中相关对的比例很高，也有很高的概率获得有偏向上的，不完全的引导程序。更容易获得已定义所有伪值的完整折刀估计。因此，我们建议使用折刀来估计与Lynch公式的遗传相关性。如果可以在每个位置收集两个以上个体的数据，我们提出了一种分组抽样方法，即使样本中的亲属比例较低，该方法也会产生与折刀相关的低标准误差。