Subcapsular sinus macrophages in lymph nodes clear lymph-borne viruses and present them to antiviral B cells

Lymph nodes prevent the systemic dissemination of pathogens such as viruses that infect peripheral tissues after penetrating the body's surface barriers. They are also the staging ground of adaptive immune responses to pathogen-derived antigens. It is unclear how virus particles are cleared from afferent lymph and presented to cognate B cells to induce antibody responses. Here we identify a population of CD11b+CD169+MHCII+ macrophages on the floor of the subcapsular sinus (SCS) and in the medulla of lymph nodes that capture viral particles within minutes after subcutaneous injection. Macrophages in the SCS translocated surface-bound viral particles across the SCS floor and presented them to migrating B cells in the underlying follicles. Selective depletion of these macrophages compromised local viral retention, exacerbated viraemia of the host, and impaired local B-cell activation. These findings indicate that CD169+ macrophages have a dual physiological function. They act as innate 'flypaper' by preventing the systemic spread of lymph-borne pathogens and as critical gatekeepers at the lymph-tissue interface that facilitate the recognition of particulate antigens by B cells and initiate humoral immune responses.     

CCL25/CCR9与骨髓祖细胞胸腺归巢

在骨髓中多种祖细胞有T细胞系潜能,但骨髓祖细胞胸腺归巢具有选择性.骨髓祖细胞胸腺归巢是多级粘附分子和趋化因子的级联过程,趋化因子CCL25及其受体CCR9在这一过程中发挥了重要作用.综述了CCL25/CCR9的结构特征及其对骨髓祖细胞胸腺归巢的作用和调节机制.     

一种塞车自动引导系统的设计

设计了一种塞车时能自动控制车辆运行的塞车引导系统．可以在低速范围内自动完成车辆的前车追踪、启动、停止等操控,减轻了驾驶员的工作负担,提高了驾驶舒适性．     

Homing behaviour of axons in the embryonic vertebrate brain

In embryonic nervous systems, growing axons must often travel long distances through diverse extracellular terrains to reach their postsynaptic partners. In most embryos, axons grow to their appropriate targets along particular tracts or nerves, as though they were following guidance cues confined to specific pathways. For example, in all vertebrates, axons from the retina invariably grow to the tectum along the well-defined optic tract. Yet, transplant experiments demonstrate that retinal axons make tectal projections even though they enter the brain at locations which are distinctly off the optic tract. Only recently has it become possible to label discreet growing projections in the embryonic vertebrate brain. Thus, it is not yet known whether displaced retinal axons grow directly towards the tectum or find it accidently, through random extension. To resolve this question, pioneering axons from normal and transplanted eyes in embryonic Xenopus were labelled using a short-survival horseradish peroxidase (HRP) method, and their orientation during growth was quantitatively assessed. The finding that the ectopic fibres head towards their distant targets implies that guidance cues are not restricted to specific pathways but are distributed throughout the embryonic brain. The significance of this result is discussed with respect to the ontogeny and evolution of the visual pathway.     

激光珩磨技术在气缸表面处理中的应用

对工件表面实施激光珩磨 ,形成与润滑磨损性能优化匹配的、连续均匀的 ,并具有一定密度、深度、角度及形状的贮油沟槽、纹路和凹腔 通过有关性能试验 ,验证了激光珩磨不仅显著提高气缸耐磨性 ,延长其寿命 ,而且还大幅度降低内燃机的颗粒排放量、机油耗、燃油耗、催化器污染和活塞环组成本 同时介绍了激光珩磨的主要技术要素 ,对激光珩磨技术的作用机理进行了理论探讨和定性分析     

Homing of a gamma delta thymocyte subset with homogeneous T-cell receptors to mucosal epithelia

In mice gamma delta T-cell populations with distinct T-cell receptor (TCR) repertoires and homing properties have been identified. Diversified populations are found in lymphoid organs and intestinal epithelia. By contrast, the gamma delta T-cells that have been found in the murine skin are homogeneous. They express a TCR consisting of one particular V gamma 5 and one particular V delta 1 chain and seem to originate from early fetal thymocytes. We have now systematically analysed many tissues by immunohistochemistry and TCR gene sequencing aided by the polymerase chain reaction. These studies revealed a second homogeneous gamma delta T-cell subset in epithelia not of the intestine and skin, but of the vagina, uterus and tongue. The TCR expressed by this gamma delta T-cell subset consists of the same V delta 1 chain. Cells that express this particular TCR have previously been shown to be positively selected in the late fetal thymus.     

Enterotypes of the human gut microbiome

Our knowledge of species and functional composition of the human gut microbiome is rapidly increasing, but it is still based on very few cohorts and little is known about variation across the world. By combining 22 newly sequenced faecal metagenomes of individuals from four countries with previously published data sets, here we identify three robust clusters (referred to as enterotypes hereafter) that are not nation or continent specific. We also confirmed the enterotypes in two published, larger cohorts, indicating that intestinal microbiota variation is generally stratified, not continuous. This indicates further the existence of a limited number of well-balanced host-microbial symbiotic states that might respond differently to diet and drug intake. The enterotypes are mostly driven by species composition, but abundant molecular functions are not necessarily provided by abundant species, highlighting the importance of a functional analysis to understand microbial communities. Although individual host properties such as body mass index, age, or gender cannot explain the observed enterotypes, data-driven marker genes or functional modules can be identified for each of these host properties. For example, twelve genes significantly correlate with age and three functional modules with the body mass index, hinting at a diagnostic potential of microbial markers.     

On the growth and form of the gut

The developing vertebrate gut tube forms a reproducible looped pattern as it grows into the body cavity. Here we use developmental experiments to eliminate alternative models and show that gut looping morphogenesis is driven by the homogeneous and isotropic forces that arise from the relative growth between the gut tube and the anchoring dorsal mesenteric sheet, tissues that grow at different rates. A simple physical mimic, using a differentially strained composite of a pliable rubber tube and a soft latex sheet is consistent with this mechanism and produces similar patterns. We devise a mathematical theory and a computational model for the number, size and shape of intestinal loops based solely on the measurable geometry, elasticity and relative growth of the tissues. The predictions of our theory are quantitatively consistent with observations of intestinal loops at different stages of development in the chick embryo. Our model also accounts for the qualitative and quantitative variation in the distinct gut looping patterns seen in a variety of species including quail, finch and mouse, illuminating how the simple macroscopic mechanics of differential growth drives the morphology of the developing gut.     

中制导信息对导弹突破质心式干扰的影响分析

质心式电子干扰是应对反舰导弹的常用电子干扰手段,基于质心干扰机理建立反舰导弹运用中制导信息突破质心式电子干扰的模型,分析了不同中制导信息和中制导距离对反舰导弹突破质心干扰的效果及其变化趋势,其结果表明中制导信息在反舰导弹突防质心干扰过程具有重要的作用。     

中制导信息对导弹突破质心式干扰影响的分析

质心式电子干扰是应对反舰导弹的常用电子干扰手段.基于质心干扰机理建立反舰导弹运用中制导信息突破质心式电子干扰的模型,分析了不同中制导信息和中制导距离对反舰导弹突破质心干扰的效果及其变化趋势.结果表明中制导信息在反舰导弹突防质心干扰过程具有重要的作用.