Gut microbiota composition correlates with diet and health in the elderly

Alterations in intestinal microbiota composition are associated with several chronic conditions, including obesity and inflammatory diseases. The microbiota of older people displays greater inter-individual variation than that of younger adults. Here we show that the faecal microbiota composition from 178 elderly subjects formed groups, correlating with residence location in the community, day-hospital, rehabilitation or in long-term residential care. However, clustering of subjects by diet separated them by the same residence location and microbiota groupings. The separation of microbiota composition significantly correlated with measures of frailty, co-morbidity, nutritional status, markers of inflammation and with metabolites in faecal water. The individual microbiota of people in long-stay care was significantly less diverse than that of community dwellers. Loss of community-associated microbiota correlated with increased frailty. Collectively, the data support a relationship between diet, microbiota and health status, and indicate a role for diet-driven microbiota alterations in varying rates of health decline upon ageing.     

Whole-genome analysis of diverse Chlamydia trachomatis strains identifies phylogenetic relationships masked by current clinical typing

Chlamydia trachomatis is responsible for both trachoma and sexually transmitted infections, causing substantial morbidity and economic cost globally. Despite this, our knowledge of its population and evolutionary genetics is limited. Here we present a detailed phylogeny based on whole-genome sequencing of representative strains of C. trachomatis from both trachoma and lymphogranuloma venereum (LGV) biovars from temporally and geographically diverse sources. Our analysis shows that predicting phylogenetic structure using ompA, which is traditionally used to classify Chlamydia, is misleading because extensive recombination in this region masks any true relationships present. We show that in many instances, ompA is a chimera that can be exchanged in part or as a whole both within and between biovars. We also provide evidence for exchange of, and recombination within, the cryptic plasmid, which is another key diagnostic target. We used our phylogenetic framework to show how genetic exchange has manifested itself in ocular, urogenital and LGV C. trachomatis strains, including the epidemic LGV serotype L2b.     

First reports of Draba pennellii and Draba pedicellata (Cruciferae) in Utah, and new distribution records for Draba kassii, Draba novolympica, and Hackelia ibapensis (Boraginaceae).

The discovery of Draba pennellii Rollins and D. pedicellata (Rollins & R.A. Price) Windham var. pedicellata, both previously known only from Nevada, is reported here from the Deep Creek Mountains of western Utah. The documentation of significant populations of D. pennellii and D. pedicellata var. pedicellata in Utah is important for accurate botanical inventories and floristic studies in both Utah and Nevada. New distribution records for D. kassii S.L. Welsh, D. novolympica Payson & St. John, and Hackelia ibapensis L.M. Shultz & J.S. Shultz are described, and the significance of these range extensions and new populations is discussed.     

几种可用于化学课堂观察的量化研究工具简析

本文主要站在化学课堂观察的角度,按照时间轴简单介绍了目前较为活跃的可以应用于化学课堂观察的量化取向的课堂观察量表、模型和范式,以及应用在化学课堂观察中可能出现的情况,并简单地分享化学课堂观察的量化研究发展历程给笔者的一些启示.     

Local positional cues in the neuroepithelium guide retinal axons in embryonic Xenopus brain

Growing retinal axons home to their distant target, the tectum, even when they are displaced from their normal pathway. This argues for long-range guidance mechanisms in the embryonic brain. Growth cones may orientate to diffusible attractants released from the target, as proposed in other systems, or they may use a stable distribution of positional information in the neuroepithelium. To distinguish between these possibilities, small pieces of the presumptive optic tract, through which retinal axons will normally grow, were rotated by approximately 90 degrees either clockwise or counterclockwise. When the retinal axons later encountered the rotated neuroepithelium, they also turned clockwise or counterclockwise, in correspondence with the direction of rotation. This demonstrates that long-range navigation of retinal axons in the vertebrate brain is based partly on stable, local positional factors, rather than on remote diffusible factors.     

Effect of calcitonin on glycosaminoglycan synthesis by embryo calf bone cells in vitro

Zusammenfassung Es wurde gefunden, dass rohe Calcitoninpräparate die Inkorporation von¹⁴C-Glucose in die Glycosaminoglycan-(GAG)-Synthese fördern. Unter denselben Zellkulturbedingungen wurde Calcitonin mit stark spezifischer Aktivität rasch inaktiviert und zeigte keine stimulierende Wirkung; wurde aber der Serumgehalt im Milieu stark eingeschränkt, so verursachte das Calcitonin (50 Einheiten/mg) eine hundertprozentige Erhöhung der¹⁴C-GAG-Synthese.     

纳米氧化锌/AC复合发泡剂在PVC糊和PP发泡中的应用研究

在AC发泡剂中添加纳米氧化锌，研究了纳米氧化锌对AC发泡剂分解的促进作用及在PVC糊和PP发泡中的应用．结果表明，在AC发泡剂中添加纳米氧化锌的样品，其初始分解温度明显低于未添加纳米氧化锌的AC发泡剂．添加纳米氧化锌的AC发泡剂，其分解速度明显高于未添加纳米氧化锌和洛加微米氧化锌的样品、在PVC糊和PP发泡中，添加纳米氧化锌的样品，发泡倍率明显高于未添加纳米氧化锌和添加微米氧化锌的样品．