The life cycles of two species of Myxomycetes in Physarales,Physarum rigidum and Didymium squamulosum

Myxomycetes are eukaryotic microorganisms containing characteristics akin to both fungi and amoebae. They can complete their whole life cycles while being cultured on agar media, and under‐laboratory conditions, which favors taxonomic, phylogenetic, and cytological researches. Here, we describe the life cycles of two such species: Didymium squamulosum collected from the field and Physarum rigidum cultured from moist chamber both belonging to the Order Physarales. Three per cent oat‐agar media (OAM) was used to culture the plasmodia until they aggregated and were almost starved. Natural light was then applied to the plasmodia to induce fructification. Their life cycles share the same common stages, namely: spore, myxamoebae, swarm cell, plasmodia, and sporulation. In this study, we describe the morphogenesis from spore to spore of two species by differential interference contrast (DIC) and stereoscopic microscopies, as well as discuss the differences between the development of both species and interspecies. We found that the spore germination method of both species was the same. However, there were differences noted in time taken and fruiting body formation. Unlike P. rigidum, the species D. squamulosum did not require natural light stimulation. Moreover, the maturation process of both species had similar color transitions but exhibited distinct morphology in each developmental stage except during the swarm cell stage.     

High genetic diversity and recombination events of porcine astrovirus strains identified from ill and asymptomatic pigs in 2017, Hunan Province,China

Astroviruses (AstV) are associated with enteric and systemic disease in mammals and birds. Astroviruses have received increased attention recently as they have been found to be associated with sporadic neurologic disease in mammals including humans. In pigs, porcine astrovirus (PoAstV) can be widely detected and has been grouped in five genotypes (PoAstV1 to PoAstV5). In the present study, we detected multiple PoAstVs in serum samples, nasal swabs, and fecal swabs collected from pigs suffering from respiratory disease or diarrhea but also from asymptomatic pigs, indicating a wide tissue tropism of the identified PoAstV genotypes. Coinfection of different genotypes in the same pig was commonly observed, and within an individual pig a high genetic diversity was observed for viruses belonging to the same PoAstV genotype. Two complete genomes of PoAstV2-WG-R2/2017 and PoAstV4-WG-R2/2017 were successfully obtained and characterized, with genome sizes of 6396 and 6643 nucleotides, respectively. The PoAstV2-WG-R2/2017 genome showed identities of 67.2–77.4% to other known PoAstV2 genomes, and the PoAstV4-WG-R2/2017 genome showed identities of 72.8–80.5% to other known PoAstV4 genomes. The predicted spike domain of open reading frame 2 (ORF2) of these strains showed the highest genetic heterogeneity, with amino acid identities of 13.7–70.9% for PoAstV2-WG-R2/2017 to other known PoAstV2 strains, and identities of 24.4–63.3% for the PoAstV4-WG-R2/2017 to other known PoAstV4 strains. Possible recombination events were identified in each of the two sequences. Two subclades of PoAstV2 and three subclades of PoAstV4 were defined in the present analyses. The obtained data provide further evidence for extraintestinal infectivity of PoAstVs, and confirmed the high genetic diversity of PoAstVs and the coinfection potential of different PoAstV types in a single pig.

     

Identification and characterization of a novel natural recombinant avian leucosis virus from Chinese indigenous chicken flock

Virus Genes - Avian leukosis virus (ALV) caused tremendous economic losses to poultry industry all over the world, especially in China. One natural recombinant ALV strain, designated as HB2015032,...     

Spatial and seasonal bacterioplankton community dynamics in the main channel of the Middle Route of South-to-North Water Diversion Project

In this study, the spatial and seasonal bacterioplankton community dynamics were investigated in the main channel of the Middle Route of the South-to-North Water Diversion Project (MRP) using Illumina HiSeq sequencing. Water samples were collected in spring and summer from south to north at eight water quality monitoring stations, respectively. The results showed that seasonal changes had a more pronounced effect on the bacterioplankton community compositions (BCCs) than spatial variation. The diversity analysis results indicated that samples of summer have more operational taxonomic units (OTUs), higher richness and diversity than those in spring. The main phyla, Proteobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria and Chloroflexi, displayed significant differences (P < 0.05) between spring and summer in the main channel. The Redundancy analysis (RDA) targeting all samples indicated that specific conductivity (SPC), dissolved oxygen (DO), pH and temperature (T) might be key factors in driving BCCs, while trophic status showed no significant correlation (P > 0.05). The present study provides important insights into the potential ecological roles of specific taxa in the new artificial ecosystem and it offers reference for studies on ecosystem succession of other giant interbasin water diversion project in the world.     

Genomic and biological characterization of the Vibrio alginolyticus-infecting “Podoviridae” bacteriophage,vB_ValP_IME271

Virus Genes - As an opportunist pathogen, Vibrio alginolyticus (V. alginolyticus), causes disease in marine animals. Bacterial contamination of seafood is not uncommon, and phage therapy is...     

Infection patterns,clinical significance,and genetic characteristics of Enterocytozoon bieneusi and Giardia duodenalis in dairy cattle in Jiangsu,China

The infection patterns and clinical significance of Enterocytozoon bieneusi and Giardia duodenalis in dairy cattle remain poorly investigated despite their common occurrence. Data on the genetic diversity are also needed to understand the transmission and human-infective potential of the two pathogens. In this study, fecal specimens from 1366 dairy cattle on a large farm were examined for the presence and genotype distribution of E. bieneusi and G. duodenalis by PCR and DNA sequencing. The overall infection rates of E. bieneusi and G. duodenalis were 13.0% and 20.6%, respectively. Pre-weaned calves had significantly higher infection rates of both pathogens than post-weaned and adult cattle (P < 0.001), with peak occurrence of the pathogens in animals of 7–12 weeks. In both pre- and post-weaned calves, animals with diarrhea were 2.1–3.0 times more likely to be infected with either pathogen than those without diarrhea (P < 0.01). The E. bieneusi identified belonged to five genotypes, including J (n = 138), I (n = 21), BEB4 (n = 10), Type IV (n = 1), and a novel genotype CHC17 (n = 1). Genotype J was the dominant one in all age groups, whereas genotype I was only identified in calves of 6–11 weeks. Genotyping of G. duodenalis at three genetic loci identified assemblage E (n = 278), assemblage A (n = 2), and concurrence of the two (n = 1). Altogether, 13, 7 and 10 subtypes of assemblage E were detected at the bg, gdh, and tpi loci, respectively, forming 65 multilocus genotypes. The formation of two major clusters of MLGs in eBURST analysis indicated that intra-assemblage genetic recombination of two dominant MLGs could have led to the high genetic heterogeneity within assemblage E on a single farm. Results of this study provide much needed data on the pathogenicity of E. bieneusi and G. duodenalis in pre- and post-weaned calves. The clinical significance of the two pathogens in dairy cattle warrants further investigations.

     

输尿管软镜碎石术围手术期肾彩色多普勒超声血流动力学评价

目的　彩用彩色多普勒超声（CDFI）对单发肾结石患者输尿管软镜碎石术围手术期肾血流动力学的评价。 方法　分析2016年7月至2018年6月共61例输尿管软镜碎石手术的单发肾结石患者,应用CDFI观察围手术期术侧肾叶间动脉血流参数,记录术前1 d、术后1 h内及术后5 d叶间动脉血流参数,并进行统计学分析。 结果　围手术期肾叶间动脉血流参数整体分析,收缩期峰值流速（Vmax）、舒张末期流速（Vmin）及阻力指数（RI）数值差异分别具有统计学意义（P<0.05）。与术前血流参数相比,术后1 h叶间动脉Vmax及Vmin均减低,RI增高（P<0.017）,术后5 d复查,Vmax及Vmin较术后1 h升高、RI较术后1 h减低（P<0.017）,与术前测值相比差异无统计学意义（P>0.017）。 结论　CDFI可以观察并量化输尿管软镜碎石术围手术期肾内动脉灌注,快速评价术侧肾血流动力学变化,手术后会出现短期、可逆性肾叶间动脉流速减低、RI增高。     

微创手术机器人机械臂结构设计与工作空间分析

目的现有双平行四边形机构设计的机械臂需要串联一个伸缩自由度机构,导致机械臂体积增大,运动灵活性降低,持镜臂与持器械臂发生干涉。针对这一问题,提出一种新型机械臂结构,增强运动灵活性、减小机械臂的体积。方法采用5连杆机构、滑块与滑轨的低副机构和丝传动机构设计机械臂,实现末端执行器的伸缩运动,建立机械臂的运动学模型,以MATLAB为仿真工具验证零位关节角D-H参数的正确性,求解出机械臂的运动方程;同时运用蒙特卡洛算法,得到末端执行器的三维工作空间范围,并对3条机械臂作术前动物实验规划;最后,在猪体内进行胆囊切除等操作,验证机械臂的双5连杆2自由度设计的合理性和可操作性。结果蒙特卡洛算法在MATLAB环境下得到的工作空间范围为:-650.4 mmx649 mm,163.8 mmy1 202 mm,-254.6 mmz829.8 mm,并成功完成16例猪的胆囊切除实验,平均操作时间为51 min。结论新型设计的双5连杆2自由度机械臂在猪体内成功完成胆囊切除等操作,且猪术后无其他不良症状,机械臂之间的运动无干涉,充分验证了所提出的微创手术机器人机械臂设计方案的可行性。     

腹主动脉瘤计算机仿真研究进展

腹主动脉瘤(abdominal aortic aneurysm,AAA)是腹主动脉较常见的疾病,破裂之后致死率极高,因此,及时发现和评估AAA破裂的风险就具有重要意义。近年来随着医学影像、计算机及血流动力学等理论和技术的快速发展,利用计算机模拟技术对AAA进行仿真研究已成为研究的热点,其模拟的结果趋于人体真实的动脉瘤,并在揭示AAA的发生及演变的机制方面发挥了重要作用。本文介绍了AAA仿真研究的原理及模型分类,详细地阐述了瘤体形态、瘤壁的结构及属性、血液及血流的属性、腔内血栓等相关因素在仿真研究中的作用,并对其目前的进展及局限性予以综述。     

数字病理扫描在颈动脉粥样硬化斑块组织学研究中的应用

目的颈动脉粥样硬化斑块的形成是脑血管病变的独立危险因素之一。对颈动脉内膜剥脱术(carotid endarterectomy,CEA)斑块进行充分的组织学判读和研究,将有助于全面把握CEA斑块的组织学表现,进而推进临床辅助诊断。方法本文我们将运用数字病理扫描仪对CEA斑块的切片经H&E染色后进行扫描,介绍数字病理扫描在CEA斑块组织学研究中的应用。结果经数字病理扫描所得的图片,有助于全面掌握和保存CEA斑块组织切片的全层面信息;在软件的帮助下有助于非常方便地测量斑块内各成分的大小;有助于精确评估斑块的狭窄程度。结论综上,数字病理成像应用于CEA斑块,结合MRI,有助于高效且准确地判读斑块组成和预测斑块稳定性,亦有助于人工智能的训练。