Wolbachia-induced thelytoky in the rose gallwasp Diplolepis spinosissimae (Giraud) (Hymenoptera : Cypinidae), and its consequences on the genetic structure of its host

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Distribution and phylogeny of Wolbachia inducing thelytoky in Rhoditini and 'Aylacini' (Hymenoptera : Cynipidae)

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doi:10.1073/pnas.0605200103 This information is current as of March 2007. High-resolution figures, a citation map, links to PubMed and Google Scholar, etc., can be found at: www.pnas.org/cgi/content/full/103/33/12487 This article cites 34 articles, 21 of which you can access for free at: www.pnas.org/cgi/content/full/103/33/12487#BIBL This article has been cited by other articles: www.pnas.org/cgi/content/full/103/33/12487#otherarticles Receive free email alerts when new articles cite this article- sign up in the box at the top right corner of the article or click here. To reproduce this article in part (figures, tables) or in entirety, see: www.pnas.org/misc/rightperm.shtml To order reprints, see: www.pnas.org/misc/reprints.shtml Involvement of Toll-like receptor 5 in the recognition of flagellated bacteri

The conduit system exports locally secreted IgM from lymph nodes

Immunoglobulin M (IgM) is the first type of antibody produced during acute infections and thus provides an early line of specific defense against pathogens. Being produced in secondary lymphoid organs, IgM must rapidly be exported to the blood circulation. However, it is currently unknown how such large pentameric molecules are released from lymph nodes (LNs). Here, we show that upon immunization, IgM transiently gains access to the luminal side of the conduit system, a reticular infrastructure enabling fast delivery of tissue-derived soluble substances to the LN parenchyma. Using microinjections of purified IgM, we demonstrate that conduit-associated IgM is delivered by neither the afferent lymph nor the blood, but is locally conveyed by conduits. Exploiting in vivo models, we further demonstrate that conduit-associated IgM is locally and transiently produced by activated, antigen-specific B cells migrating in the T cell zone. Thus, our study reveals that the conduit system is coopted by B cells to rapidly export secreted IgM out of LNs

High endothelial venules as traffic control points maintaining lymphocyte population homeostasis in lymph nodes

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Reticular Fibroblasts Expressing the Transcription Factor WT1 Define a Stromal Niche that Maintains and Replenishes Splenic Red Pulp Macrophages

International audienceLocated within red pulp cords, splenic red pulp macrophages (RPMs) are constantly exposed to the bloodflow, clearing senescent red blood cells (RBCs) and recycling iron from hemoglobin. Here, we studied themechanisms underlying RPM homeostasis, focusing on the involvement of stromal cells as these cellsperform anchoring and nurturing macrophage niche functions in lymph nodes and liver. Microscopy revealedthat RPMs are embedded in a reticular meshwork of red pulp fibroblasts characterized by the expression ofthe transcription factor Wilms’ Tumor 1 (WT1) and colony stimulating factor 1 (CSF1). Conditional deletion ofCsf1in WT1+red pulp fibroblasts, but not white pulp fibroblasts, drastically altered the RPM network withoutaltering circulating CSF1 levels. Upon RPM depletion, red pulp fibroblasts transiently produced the mono-cyte chemoattractants CCL2 and CCL7, thereby contributing to the replenishment of the RPM network.Thus, red pulp fibroblasts anchor and nurture RPM, a function likely conserved in humans

Clonal Proliferation and Stochastic Pruning Orchestrate Lymph Node Vasculature Remodeling

International audienceLymph node (LN) expansion during an immune response relies on the transient remodeling of its vasculature. Although the mechanisms driving LN endothelial cell division are beginning to be understood, a comprehensive view of LN endothelial cell dynamics at the single-cell level is lacking. Here, we used multicolored fluorescent fate-mapping models to track the behavior of blood endothelial cells during LN expansion upon inflammation and subsequent return to homeostasis. We found that expansion of the LN vasculature relied on the sequential assembly of endothelial cell proliferative units. This segmented growth was sustained by the clonal proliferation of high endothelial venule (HEV) cells, which act as local progenitors to create capillaries andHEVneo-vessels at the periphery of the LN. Return to homeostasis was accompanied by the stochastic death of pre-existing and neo-synthesized LN endothelial cells. Thus, our fate-mapping studies unravel-at a single-cell level-the complex dynamics of vascular-tree remodeling during LN expansion and contraction

Neutralization of Human Immunodeficiency Virus Type 1 by Antibody to gp120 Is Determined Primarily by Occupancy of Sites on the Virion Irrespective of Epitope Specificity

We investigated the relative importance of binding site occupancy and epitope specificity in antibody neutralization of human immunodeficiency virus (HIV) type 1 (HIV-1). The neutralization of a T-cell-line-adapted HIV-1 isolate (MN) was analyzed with a number of monovalent recombinant Fab fragments (Fabs) and monoclonal antibodies with a range of specificities covering all confirmed gp120-specific neutralization epitopes. Binding of Fabs to recombinant monomeric gp120 was determined by surface plasmon resonance, and binding of Fabs and whole antibodies to functional oligomeric gp120 was determined by indirect immunofluorescence and flow cytometry on HIV-infected cells. An excellent correlation between neutralization and oligomeric gp120 binding was observed, and a lack of correlation with monomeric gp120 binding was confirmed. A similar degree of correlation was observed between oligomeric gp120 binding and neutralization with a T-cell-line-adapted HIV-1 molecular clone (Hx10). The ratios of oligomer binding/neutralization titer fell, in general, within a relatively narrow range for antibodies to different neutralization epitopes. These results suggest that the occupancy of binding sites on HIV-1 virions is the major factor in determining neutralization, irrespective of epitope specificity. Models to account for these observations are proposed

Lymphatic Endothelial Cells Are Essential Components of the Subcapsular Sinus Macrophage Niche

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