ABSTRACT
The gut microbiota contributes to host health and fitness, and imbalances in its composition are associated with pathology. However, what shapes microbiota composition is not clear, in particular the role of genetic factors. Previous work in Caenorhabditis elegans defined a characteristic worm gut microbiota significantly influenced by host genetics. The current work explores the role of central regulators of host immunity and stress resistance, employing qPCR and CFU counts to measure abundance of core microbiota taxa in mutants raised on synthetic communities of previously-isolated worm gut commensals. This revealed a bloom, specifically of Enterobacter species, in immune-compromised TGFß/BMP mutants. Imaging of fluorescently labeled Enterobacter showed that TGFß/BMP-exerted control operated primarily in the anterior gut and depended on multi-tissue contributions. Enterobacter commensals are common in the worm gut, contributing to infection resistance. However, disruption of TGFß/BMP signaling turned a normally beneficial Enterobacter commensal to pathogenic. These results demonstrate specificity in gene-microbe interactions underlying gut microbial homeostasis and highlight the pathogenic potential of their disruption.
Subject(s)
Bone Morphogenetic Proteins/immunology , Caenorhabditis elegans Proteins/immunology , Caenorhabditis elegans/immunology , Gastrointestinal Microbiome/immunology , Transforming Growth Factor beta/immunology , Animals , Animals, Genetically Modified , Bacteria/classification , Bacteria/genetics , Bacteria/growth & development , Bone Morphogenetic Proteins/genetics , Bone Morphogenetic Proteins/metabolism , Caenorhabditis elegans/genetics , Caenorhabditis elegans/microbiology , Caenorhabditis elegans Proteins/genetics , Caenorhabditis elegans Proteins/metabolism , Enterobacter/genetics , Enterobacter/immunology , Enterobacter/physiology , Gastrointestinal Microbiome/genetics , Gastrointestinal Microbiome/physiology , Homeostasis/immunology , Host Microbial Interactions/immunology , Mutation/immunology , Population Dynamics , RNA, Ribosomal, 16S/genetics , Signal Transduction/genetics , Signal Transduction/immunology , Transforming Growth Factor beta/genetics , Transforming Growth Factor beta/metabolismABSTRACT
Manual cerebrospinal fluid (CSF) and body fluid cell counts done using a hemacytometer are labor-intensive and time-consuming. The automated Iris iQ200 with the Body Fluids Module (Iris Diagnostics, Chatsworth, CA) counts RBCs and nucleated cells in CSF and other body fluids using flow cell digital imaging. We compared the cell counts from the iQ200 and the hemacytometer. CSF and body fluid samples were first analyzed in duplicate using the Neubauer hemacytometer. We then counted the samples on the iQ200. CSF samples for RBC counts of 0 to 6.7 x 10(5)/microL and nucleated cell counts of 0 to 1,707/microL resulted in r = 0.996 and r = 0.998, respectively. Body fluid samples for RBC counts of 0 to 2.7 x 10(5)/microL and nucleated cell counts of 0 to 1.1 x 10(4)/microL resulted in r = 0.988 and r = 0.987, respectively. Day-to-day precision with quality control yielded coefficients of variation of 12.5% and 13.3% for RBC counts and 9.4% and 12.3% for nucleated cell counts. Linearity studies yielded slopes of 0.99 and 1.010 for RBC and nucleated cell counts, respectively. The results from the iQ200 correlate well with the manual hemacytometer method.
