Infection with Salmonella enterica Serovar Typhimurium Leads to Increased Proportions of F4/80+ Red Pulp Macrophages and Decreased Proportions of B and T Lymphocytes in the Spleen.

Infection of mice with Salmonella enterica serovar Typhimurium (Salmonella) causes systemic inflammatory disease and enlargement of the spleen (splenomegaly). Splenomegaly has been attributed to a general increase in the numbers of phagocytes, lymphocytes, as well as to the expansion of immature CD71+Ter119+ reticulocytes. The spleen is important for recycling senescent red blood cells (RBCs) and for the capture and eradication of blood-borne pathogens. Conservation of splenic tissue architecture, comprised of the white pulp (WP), marginal zone (MZ), and red pulp (RP) is essential for initiation of adaptive immune responses to captured pathogens. Using flow cytometry and four color immunofluorescence microscopy (IFM), we show that Salmonella-induced splenomegaly is characterized by drastic alterations of the splenic tissue architecture and cell population proportions, as well as in situ cell distributions. A major cause of splenomegaly appears to be the significant increase in immature RBC precursors and F4/80+ macrophages that are important for recycling of heme-associated iron. In contrast, the proportions of B220+, CD4+ and CD8+ lymphocytes, as well as MZ MOMA+ macrophages decrease significantly as infection progresses. Spleen tissue sections show visible tears and significantly altered tissue architecture with F4/80+ macrophages and RBCs expanding beyond the RP and taking over most of the spleen tissue. Additionally, F4/80+ macrophages actively phagocytose not only RBCs, but also lymphocytes, indicating that they may contribute to declining lymphocyte proportions during Salmonella infection. Understanding how these alterations of spleen microarchitecture impact the generation of adaptive immune responses to Salmonella has implications for understanding Salmonella pathogenesis and for the design of more effective Salmonella-based vaccines

Data from: Functional trait evolution in Sphagnum peat mosses and its relationship to niche construction

Species in the genus Sphagnum create, maintain, and dominate boreal peatlands through ‘extended phenotypes’ that allow these organisms to engineer peatland ecosystems and thereby impact global biogeochemical cycles. One such phenotype is the production of peat, or incompletely decomposed biomass, that accumulates when rates of growth exceed decomposition. Interspecific variation in peat production is thought to be responsible for the establishment and maintenance of ecological gradients, such as the microtopographic hummock-hollow gradient, along which sympatric species sort within communities. This study investigated the mode and tempo of functional trait evolution across 15 species of Sphagnum using data from the most extensive studies of Sphagnum functional traits to date and phylogenetic comparative methods. We found evidence for phylogenetic conservatism of the niche descriptor height-above-water-table and of traits related to growth, decay, and litter quality. However, we fail to detect the influence of phylogeny on interspecific variation in other traits such as shoot density and suggest that environmental context can obscure phylogenetic signal. Trait correlations indicate possible adaptive syndromes that may relate niche and its construction. This study is the first to formally test the extent to which functional trait variation among Sphagnum species is a result of shared evolutionary history

Maximum clade credibility tree

The maximum clade credibility tree used for phylogenetic analyses in Nexus format. The TreeAnnotator package within the BEAST2 toolkit was used to summarize the posterior tree distribution with median node heights

Trees from Bayesian posterior distribution

A set of 1,000 trees randomly drawn from the concatenated posterior distribution of three independent BEAST2 runs after 10% burn-in

BEAST2 Configuration File

An XML file used in BEAST2 to infer phylogenetic relationships. The file contains the DNA sequence alignment, data partitions, and parameter information used for BEAST2 analyses

Infection with <i>Salmonella</i> leads to decreased proportions of CD4⁺ and CD8⁺ T lymphocytes in the spleen.

<p>Spleens of C57BL/6 mice infected with 1x10⁵ CFUs of <i>Salmonella</i> were stained with antibodies specific for CD4 and CD8 cell markers. (A) Images were analyzed using Volocity software and the image area (pixels) containing CD4⁺ or CD8⁺ T lymphocytes were expressed as a percentage of the total area from 5 images per mouse spleen (n = 3 mice per time point). (B) Proportions of CD4⁺ and CD8⁺ splenocytes in cell suspensions of C57BL/6 mice infected with 1x10⁵ CFUs of <i>Salmonella</i> at day 0 (control), 6, 9, and 21 days post-infection analyzed by flow cytometry. Data are expressed as the mean ± standard deviation (n = 3 mice per time point). Group means that do not share a superscript are significantly different from each other (p< 0.05). (C) Representative images of spleens from control mice and mice infected with 1x10⁵ CFUs of <i>Salmonella</i> showing changes in the proportions of CD4⁺ (top row, red) or CD8⁺ cells (bottom row, red). Actin staining with phalloidin-Alexa350 (green) highlights the tissue architecture.</p

Infection with <i>Salmonella</i> causes anemia and alters proportions of erythroid cell populations in peripheral blood.

<p>C57BL/6 mice were infected i.v. with 1x10⁵ CFUs of <i>Salmonella</i> and at day 0 (uninfected control), 9, 14, and 21, blood samples were collected. (A) PCV (%) was calculated by dividing packed cell volume by total blood volume. (B) Blood samples were stained with fluorescent antibodies specific for erythroid cell markers CD71 and Ter119, then analyzed by flow cytometry. Proportions of CD71⁺ Ter119^-, CD71⁺ Ter119⁺, and CD71^- Ter119⁺ reticulocytes are shown as means ± standard deviation (n = 3 mice per time point). (C) Representative flow cytometry contour plots of blood samples taken at day 0, 9, 14, and 21 post-infection. Group means that do not share superscripts are significantly different from each other (p< 0.05).</p

Infection with <i>Salmonella</i> leads to the destruction of B cell follicles in the spleen and diminishes the proportions of B220⁺ lymphocytes.

<p>C57BL/6 mice were infected i.v. with 5x10⁵ CFUs (high dose) or 1x10⁵ CFUs (low dose) of <i>Salmonella</i> and at 0 (uninfected control), 3, 6, 9, 14, and 21 days post-infection, spleen sections were stained with monoclonal antibodies specific for the B220 cell marker. (A) Five images per mouse spleen (n = 3 mice per time point) were analyzed using Volocity software and the image area containing B220⁺ lymphocytes (red) was expressed as a percent of the total image area. (B) Spleen single-cell suspensions were stained with antibodies specific for the B220 cell marker and analyzed by flow cytometry. Data are expressed as the mean ± standard deviation (n = 3 mice per time point. The mean value for day 14 is averaged from 2 mice. Group means that do not share a superscript are significantly different from each other (p< 0.05). (C) Representative images of spleen tissue sections from uninfected mice (day 0) or mice infected with 5x10⁵ CFUs of <i>Salmonella</i> (B220⁺ B cells, red). Actin staining with phalloidin-Alexa350 (green) highlights the tissue architecture. (D) Representative flow cytometry contour plots showing proportions of B220⁺ splenocytes at day 0, 6, 9, and 14 post-infection.</p