title: Space Environmental Factor Impacts upon Murine Colon Microbiota and Mucosal Homeostasis.
abstract: Astronaut intestinal health may be impacted by microgravity, radiation, and diet. The aim of this study was to characterize how high and low linear energy transfer (LET) radiation, microgravity, and elevated dietary iron affect colon microbiota (determined by 16S rDNA pyrosequencing) and colon function. Three independent experiments were conducted to achieve these goals: 1) fractionated low LET γ radiation (137Cs, 3 Gy, RAD), high Fe diet (IRON) (650 mg/kg diet), and a combination of low LET γ radiation and high Fe diet (IRON+RAD) in male Sprague-Dawley rats; 2) high LET 38Si particle exposure (0.050 Gy), 1/6 G partial weight bearing (PWB), and a combination of high LET38Si particle exposure and PWB in female BalbC/ByJ mice; and 3) 13 d spaceflight in female C57BL/6 mice. Low LET radiation, IRON and spaceflight increased Bacteroidetes and decreased Firmicutes. RAD and IRON+RAD increased Lactobacillales and lowered Clostridiales compared to the control (CON) and IRON treatments. Low LET radiation, IRON, and spaceflight did not significantly affect diversity or richness, or elevate pathogenic genera. Spaceflight increased Clostridiales and decreased Lactobacillales, and similar trends were observed in the experiment using a ground-based model of microgravity, suggesting altered gravity may affect colonic microbiota. Although we noted no differences in colon epithelial injury or inflammation, spaceflight elevated TGFβ gene expression. Microbiota and mucosal characterization in these models is a first step in understanding the impact of the space environment on intestinal health.
authors.affiliation: Intercollegiate Faculty of Genetics, Texas A&M University, College Station, Texas, United States of America.
authors.forename: Lauren E
authors.initials: LE
authors.lastname: Ritchie
authors.affiliation: Nutrition & Food Science Department, Texas A&M University, College Station, Texas, United States of America.
authors.forename: Stella S
authors.initials: SS
authors.lastname: Taddeo
authors.affiliation: Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas, United States of America.
authors.forename: Brad R
authors.initials: BR
authors.lastname: Weeks
authors.affiliation: Division of Nephrology, Department of Medicine, University of Kentucky, Lexington, Kentucky, United States of America.
authors.forename: Florence
authors.initials: F
authors.lastname: Lima
authors.affiliation: Department of Health and Kinesiology, Texas A&M University, College Station, Texas, United States of America.
authors.forename: Susan A
authors.initials: SA
authors.lastname: Bloomfield
authors.affiliation: Department of Cell Biology and Physiology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America.
authors.forename: M Andrea
authors.initials: MA
authors.lastname: Azcarate-Peril
authors.affiliation: Human Health and Performance Directorate, NASA Lyndon B. Johnson Space Center, Houston, Texas, United States of America.
authors.forename: Sara R
authors.initials: SR
authors.lastname: Zwart
authors.affiliation: Human Health and Performance Directorate, NASA Lyndon B. Johnson Space Center, Houston, Texas, United States of America.
authors.forename: Scott M
authors.initials: SM
authors.lastname: Smith
authors.affiliation: Intercollegiate Faculty of Genetics, Texas A&M University, College Station, Texas, United States of America; Nutrition & Food Science Department, Texas A&M University, College Station, Texas, United States of America.
authors.forename: Nancy D
authors.initials: ND
authors.lastname: Turner
mesh_terms: D000818:Animals; D041963:Bacteroidetes / Q000235:genetics / Q000302:isolation & purification; D001483:Base Sequence; D000068016:Eubacteriales / Q000235:genetics / Q000302:isolation & purification; D003106:Colon / Q000382:microbiology*; D015169:Colony Count, Microbial; D005260:Female; D000068536:Bacillota / Q000235:genetics / Q000302:isolation & purification; D000069196:Gastrointestinal Microbiome / Q000235:genetics*; D015870:Gene Expression; D006706:Homeostasis / Q000502:physiology*; D007413:Intestinal Mucosa / Q000382:microbiology*; D056546:Lactobacillales / Q000235:genetics / Q000302:isolation & purification; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D012336:RNA, Ribosomal, 16S / Q000235:genetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013026:Space Flight; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism; D014893:Weightlessness; D018474:Weightlessness Simulation
chemical_list: D012336:RNA, Ribosomal, 16S; D016212:Transforming Growth Factor beta