老年人肠道乳酸菌的分离与鉴定及其来源发酵乳杆菌的遗传进化分析

首先对湖北襄阳和恩施地区的健康老年人肠道乳酸菌进行分离与鉴定，然后从中选择发酵乳杆菌（Lactobacillus fermentum）进行多位点序列分型（multilocus sequence typing，MLST）分析。结果显示，基于可培养方法，湖北襄阳与恩施地区老年人肠道乳酸菌可以鉴定为以乳杆菌属（Lactobacillus）为主的5 个菌属，15 个种。总的来说，发酵乳杆菌和唾液乳杆菌（L. salivarius）占老年人肠道源乳酸菌分离株总量的55%左右，表明人体肠道可以作为发酵乳杆菌的重要分离来源。基于8 个持家基因的MLST分析表明，25 株来源于肠道的发酵乳杆菌可以划分为25 个序列型，具有极高的遗传多样性；基于选择压力分析与phi-test，选用的8 个持家基因均受到纯化选择作用，且其中仅基因rpoB显著经历了基因重组事件；另外，基于Prim’s和goeBURST的进化分析表明，一半左右的肠道源发酵乳杆菌倾向于形成单独的分支，表明它们具有一定的宿主特异性，可能的原因是为适应肠道环境，这些发酵乳杆菌经历了有异于发酵食品生境的进化历程。     

2017—2019年郴州市食源性疾病主动监测病原学特征及耐药分析

目的 了解郴州市食源性疾病的病原学特征和流行规律,为食源性疾病预防控制措施提供科学依据。方法 收集2017—2019年郴州市2家哨点医院主动监测的病例信息、粪便或肛拭子标本,依据《国家食源性疾病监测工作手册》中的方法对标本开展病原学检验、病原体分型以及药敏试验。结果 采集腹泻病例标本825份,病原体总检出率为30.18%（249/825）,其中沙门菌16.24%（134/825）、诺如病毒11.76%（97/825）、致泻大肠埃希菌3.52%（29/825）、副溶血性弧菌0.73%（6/825）、志贺菌0.12%（1/825）;第二、第三季度细菌检出率高,第一、第四季度病毒检出率高;不同年龄段病原体检出率以2～6岁年龄段最高（40.79%,31/76）;可疑暴露食品主要为乳及乳制品、粮食类及其制品和水果类及其制品;检出的沙门菌中以鼠伤寒沙门菌占比最高（74.63%,100/134）,致泻大肠埃希菌中以肠黏附型（EAEC）和产肠毒素型（ETEC）占比最高（34.48%,10/29）,诺如病毒以GⅡ型为主（85.57%,83/97）;沙门菌对四环素（TET）耐药率最高达88.71%（110/124）,沙门菌多重耐药率达85.48%（106/124）;致泻大肠埃希菌对氨苄西林（AMP）耐药率较高（79.31%,23/29）,致泻大肠埃希菌多重耐药率为62.07%（18/29）。结论 郴州市食源性疾病腹泻病例的主要病原体为沙门菌和诺如病毒,沙门菌和致泻大肠埃希菌耐药严重,应针对性地开展食品安全监管,强化抗生素耐药监测,严防抗生素滥用。     

肺腺癌CT影像分子分型研究进展

研究表明在明确驱动基因后进行特异性靶向治疗,肺癌患者的中位生存期显著延长。而除高通量测序技术和荧光原位杂交等分子生物学技术外,影像基因组学的出现,也为肺腺癌分子分型预测提供了一种无创的新方法。本文对肺腺癌计算机断层扫描（computed tomography,CT）影像分子分型的研究进展进行综述。首先,介绍肺腺癌分子分型的研究背景及肺腺癌主要的基因突变类型;然后,重点介绍两种主要的研究方法,即CT语义特征与肺腺癌分子亚型的相关性分析和基于机器学习的肺腺癌分子分型预测模型;最后,总结了该领域现阶段面临的主要问题,并对未来的研究方向做出展望。肺腺癌CT影像分子分型研究已经取得了一定成果,但仍存在很多问题。相关性分析与基于影像组学的预测模型研究由于样本各异且受过多人为干预,导致研究结果差异大,甚至有部分文献得到的结论截然相反。而基于深度学习的预测模型研究采用端到端的神经网络模型,人为参与极少,降低了研究难度,但尚处于起步阶段,构建的模型大多相对简单,远不能达到临床应用标准。今后的研究应聚焦于结合多种医学图像构建肺腺癌分子分型的大样本深度学习预测模型,同时结合临床信息、语义特征及影像组学特征,实现肺腺癌分子分型的无创、精准预测。     

Short communication: Identification of variation in the ovine prolactin gene of Chios sheep with a cost-effective sequence-based typing assay

The present study identified single nucleotide polymorphisms (SNP) in the coding and untranslated regions of the ovine prolactin gene of Chios sheep. By developing a cost-effective direct sequence-based typing assay, around 600 bp of reliable sequencing data and clear identification of heterozygous positions was achieved. Five SNP were found, located in exons 2 (KC764410:g.567G>A, g.625C>T, g.683C>A) and 3 (KC764410:g.2015C>A, g.2101G>A), whereas the remaining exons were monomorphic. The identified SNP were synonymous, with the exception of the g.567G>A SNP, which results in an Arg to His amino acid change. As the sequencing cost of the sequence-based typing assay was 20 orders of magnitude lower compared with a standard Sanger method, the assay was also used as a genotyping tool. The identified polymorphism was genotyped for 247 ewes and was subsequently used in mixed model association analyses of milk yield, milk fat content, and litter size at birth. The association analysis revealed a significant dominance effect of 0.17 ± 0.07 of the g.2015C>A SNP on milk fat percentage, whereas a dominance effect of ?21.33 ± 10.51 of the same SNP on total lactation milk yield was also estimated. The g.2015C>A SNP explained 2.47 and 3.68% of the total phenotypic variance of milk yield and milk fat percentage, respectively, whereas the corresponding values for the animal variance were 7.14 and 11.75%. A suggestive association of the nonsynonymous g.567G>A SNP with litter size at birth was also detected.     

Prevalence and diversity of Wolbachia bacteria infecting insect pests of stored products

Wolbachia are common bacterial symbionts of insects. Because infections of these bacteria can alter the reproduction and biology of the host, there is interest in the potential use of Wolbachia to control populations of pest species. To advance this research, we screened 38 species (88 populations from 16 countries) of stored-product insect pests for Wolbachia infections. Infections were detected in nine species of Coleoptera (Anobiidae – Lasioderma serricorne (Fabricius), Stegobium paniceum (Linnaeus); Curculionidae – Sitophilus oryzae (Motschulsky), Sitophilus zeamais Motschulsky; Dermestidae – Attagenus unicolor (Brahm), Dermestes lardarius Linnaeus; Silvanidae – Oryzaephilus mercator (Fauvel), Oryzaephilus surinamensis (Linnaeus); Tenebrionidae – Tribolium confusum Jaquelin Du Val), one species of Hymenoptera (Trichogrammatidae – Trichogramma deion Pinto & Oatman), and one species of Lepidoptera (Pyralidae – Ephestia kuehniella Zeller). Phylogenetic analyses based on wsp gene sequences identified all Wolbachia isolates as members of Supergroups A or B. Additional sequences for the genes gatB, coxA, hcpA, fbpA and ftsZ were obtained for use in multilocus sequence typing (MLST) to identify the sequence types to which the isolates belonged. Our results identify five new Wolbachia-insect associations and support previous findings that infections of Wolbachia in stored-product insect pests are members of Supergroups A or B.     

Development of a novel multi-locus variable-number tandem repeat analysis (MLVA) combined with high resolution melting analysis (HRMA) for Listeria innocua typing and its application in a food processing plant

Listeria monocytogenes is the causative bacteria of listeriosis, a type of food poisoning with high mortality, which mainly infects people through the consumption of ready-to-eat food. Most cases of L. monocytogenes contamination have occurred at food processing plants. Therefore, food companies must carefully monitor the proliferation and spread of this bacterium. Listeria innocua has often been reported to exist in food processing plants when the presence of the genus Listeria is investigated. In addition, because L. innocua and L. monocytogenes are known to act together, L. innocua is an important hygiene indicator for food companies. Multilocus variable-number tandem repeat analysis (MLVA) is a method used to discriminate between strains, based on the discrepancies in the number of repeating units within the tandem repeats (TRs). In many cases, MLVA uses capillary electrophoresis (CE) or base sequence analysis. However, the equipment used for these analyses is expensive, and requires a certain level of knowledge and skill for operation. Therefore, it is only used at research facilities. However, in order to rapidly trace the sources of contamination in food processing plants, it is necessary to easily discriminate between strains within the working areas. Therefore, in this study, we established a simpler MLVA method, using high resolution melting analysis (HRMA) to analyze the diversity of variable-number of tandem repeats (VNTRs). We investigated three VNTR loci (used in a previous MLVA-CE analysis) using MLVA-HRMA. The MLVA-HRMA of 23 L. innocua strains showed that this method differentiates between strains at a more or less equal level with MLVA, which uses base sequence analysis. HRMA is also used to investigate gene polymorphisms based on the Tm value of the PCR products. Therefore, a different peak pattern is observed depending on the internal SNP even if the number of repeating units are the same. We then evaluated the efficacy of MLVA-HRMA in differentiating between 96 strains isolated at food processing plants. This analysis demonstrated the usefulness of the MLVA-HRMA method and its discriminatory ability in tracing the sources of contamination in food processing plants. Since this method is simpler, and cheaper than the existing MLVA methods, it could see widespread use in food processing plants as a rapid investigative tool.     

A hybrid class- and prototype-based object model to support language-neutral structural intercession

ContextDynamic languages have turned out to be suitable for developing specific applications where runtime adaptability is an important issue. Although .Net and Java platforms have gradually incorporated features to improve their support of dynamic languages, they do not provide intercession for every object or class. This limitation is mainly caused by the rigid class-based object model these platforms implement, in contrast to the flexible prototype-based model used by most dynamic languages.ObjectiveOur approach is to provide intercession for any object or class by defining a hybrid class- and prototype-based object model that efficiently incorporates structural intercession into the object model implemented by the widespread .Net and Java platforms.MethodIn a previous work, we developed and evaluated an extension of a shared-source implementation of the .Net platform. In this work, we define the formal semantics of the proposed reflective model, and modify the existing implementation to include the hybrid model. Finally, we assess its runtime performance and memory consumption, comparing it to existing approaches.ResultsOur platform shows a competitive runtime performance compared to 9 widespread systems. On average, it performs 73% and 61% better than the second fastest system for short- and long-running applications, respectively. Besides, it is the JIT-compiler approach that consumes less average memory. The proposed approach of including a hybrid object-model into the virtual machine involves a 444% performance improvement (and 65% less memory consumption) compared to the existing alternative of creating an extra software layer (the DLR). When none of the new features are used, our platform requires 12% more execution time and 13% more memory than the original .Net implementation.ConclusionOur proposed hybrid class- and prototype-based object model supports structural intercession for any object or class. It can be included in existing JIT-compiler class-based platforms to support common dynamic languages, providing competitive runtime performance and low memory consumption.     

Isolation and characterization of Listeria monocytogenes in Chinese food obtained from the central area of China

The objective of this study was to investigate the prevalence and characteristics of Listeria monocytogenes isolated from Chinese food, including frozen dumplings, flavored raw meat, roasted meat, braised meat, and a cold vegetable dish with sauce. A total of 900 food samples were collected from supermarkets, open-air markets, and delicatessens in three large cities in the central area of China to examine the presence of L. monocytogenes; 21 (2.3%) of the samples were positive for this pathogen. Among the different samples, braised meat showed the highest L. monocytogenes detection rate (4.4%). Samples obtained from delicatessens showed a much higher L. monocytogenes contamination rate (8.3%) than those from open-air markets (6.7%) or supermarkets (0%). Multilocus sequence typing (MLST) analysis indicated that the 21 bacterial isolates belonged to 12 ST subgroups. ST5 was the largest and contained 7 isolates (33.3%); it was followed by ST474, ST121 and ST9 (each containing 2 isolates [10.5%]). Antibiotic susceptibility analysis showed that the 21 L. monocytogenes isolates were thoroughly resistant to cefoxitin but highly susceptible to doxycycline and ciprofloxacin. The presence of 10 virulence genes was evaluated by PCR, which showed that inlA, inlC, inlJ, prfA, hlyA, and plcB were present in all isolates and that inlB, actA, plcA and iap were present in 71.4–90.5% of the isolates. This study provides a useful reference for risk assessment and control of L. monocytogenes contamination in Chinese food and for the treatment of clinical listeriosis.     

Reactions,accuracy and response complexity of numerical typing on touch screens

Touch screens are popular nowadays as seen on public kiosks, industrial control panels and personal mobile devices. Numerical typing is one frequent task performed on touch screens, but this task on touch screen is subject to human errors and slow responses. This study aims to find innate differences of touch screens from standard physical keypads in the context of numerical typing by eliminating confounding issues. Effects of precise visual feedback and urgency of numerical typing were also investigated. The results showed that touch screens were as accurate as physical keyboards, but reactions were indeed executed slowly on touch screens as signified by both pre-motor reaction time and reaction time. Provision of precise visual feedback caused more errors, and the interaction between devices and urgency was not found on reaction time. To improve usability of touch screens, designers should focus more on reducing response complexity and be cautious about the use of visual feedback.

Practitioner Summary: The study revealed that slower responses on touch screens involved more complex human cognition to formulate motor responses. Attention should be given to designing precise visual feedback appropriately so that distractions or visual resource competitions can be avoided to improve human performance on touch screens.