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Related Concept Videos

Physiology of Enteric Nervous System and Gut Health01:05

Physiology of Enteric Nervous System and Gut Health

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The gastrointestinal tract, responsible for the digestion and absorption of nutrients, is safeguarded by the intestinal barrier, which consists of secretory, physical, and immune components. At the forefront is the secretory barrier, composed of essential elements such as mucus, gut microbiota, and defense proteins. They collaborate to break down food particles, facilitate nutrient absorption, and maintain optimal gut health. These secretory components ensure the smooth functioning of the...
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Among the three main modes of HGT—transformation, conjugation, and transduction—transduction is unique in that it is mediated by bacteriophages, or bacterial viruses.Transduction occurs in two ways. Generalized transduction occurs during the lytic cycle of a bacteriophage infection. In this process, bacteriophages infect bacterial cells, replicate within them, and ultimately cause cell lysis, releasing newly assembled virions. Occasionally, random fragments of the bacterial genome...
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Defense Mechanism Against Infection01:26

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Natural flora, body system defenses, and inflammation are natural barriers of the body against infectious agents regardless of previous exposure. Normal floras of the human body refer to the microbial population that colonizes the skin and mucous membranes.
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Mucosal Barrier of the Stomach01:25

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The gastric glands contain parietal cells that secrete hydrochloric acid (HCl) for digestion. The cells secrete HCl because it is highly corrosive and essential for breaking down food. To achieve this, they secrete hydrogen and chloride ions into the lumen of the gastric glands, which combine to form HCl.
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Renewal of Intestinal Stem Cells01:23

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The intestinal epithelial lining rapidly renews every 4 to 5 days. The renewal is facilitated by intestinal stem cells (ISCs) located at the base of the crypt– a gland located at the bottom of each villus. ISCs divide asymmetrically to form new stem cells and progenitor daughter cells. The daughter cells are called transit-amplifying (TA) cells which move upwards along the crypt and either differentiate into absorptive cells– the enterocytes or secretory cells– including the...
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Surface Membrane Barriers

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The skin and mucous membranes serve as the primary line of defense against pathogens by providing both physical and chemical protection. These barriers are essential in preventing the entry and establishment of microbes, thereby maintaining the integrity of the host.
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Related Experiment Video

Updated: Mar 1, 2026

Injections of Lipopolysaccharide into Mice to Mimic Entrance of Microbial-derived Products After Intestinal Barrier Breach
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Exploiting a host-commensal interaction to promote intestinal barrier function and enteric pathogen tolerance.

Virginia A Pedicord1,2, Ainsley A K Lockhart1, Kavita J Rangan2

  • 1Laboratory of Mucosal Immunology, The Rockefeller University, New York, NY, USA.

Science Immunology
|June 6, 2017
PubMed
Summary

A specific bacterium, Enterococcus faecium, enhances gut barrier defenses against pathogens like Salmonella Typhimurium and Clostridium difficile. Its unique enzyme, SagA, can be used to boost resistance to enteric infections.

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Area of Science:

  • Microbiology
  • Immunology
  • Gastroenterology

Background:

  • Commensal gut bacteria play a role in preventing infections.
  • Understanding the mechanisms of pathogen resistance mediated by specific commensal species is crucial for therapeutic development.

Purpose of the Study:

  • To investigate how the human commensal Enterococcus faecium protects against enteric infections.
  • To identify the specific bacterial factors and host mechanisms involved in this protection.

Main Methods:

  • Colonization of mice with Enterococcus faecium.
  • Analysis of host intestinal epithelial defense programs.
  • Identification of bacterial factors using genetic approaches.
  • Ectopic expression of bacterial factors in other bacteria.

Main Results:

  • Enterococcus faecium colonization enhances host intestinal epithelial defense against Salmonella Typhimurium.
  • Protection is mediated by the peptidoglycan hydrolase SagA and requires host pattern recognition receptors and antimicrobial peptides.
  • Ectopic expression of SagA confers resistance against Salmonella Typhimurium and Clostridium difficile.

Conclusions:

  • Enterococcus faecium enhances host barrier function to limit enteric pathogen pathogenesis.
  • The bacterial enzyme SagA is a key factor in mediating this protection.
  • Specific factors from commensal bacteria can be harnessed to improve host defense and combat distinct enteric infections.