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Related Concept Videos

Complement System01:27

Complement System

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The complement system is a group of approximately 20 plasma proteins that strengthen the body's defenses against infections through opsonization, inflammation, and cell lysis. Opsonization involves coating pathogens with complement proteins, making them more recognizable and facilitating phagocyte engulfment. Certain complement proteins induce inflammation that attracts immune cells to the site of infection. Cell lysis involves the destruction of pathogens through the formation of a...
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A complementation test is a simple cross to identify whether the two mutations are located on the same gene or different genes. It was first performed by Edward Lewis in the 1940s while working on fruit flies. He developed the test to identify the location and arrangement of different mutations on chromosomes.
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Tissue-specific transcription factors contribute to diverse cellular functions in mammals. For example, the gene for beta globin, a major component of hemoglobin, is present in all cells of the body. However, it is only expressed in red blood cells because the transcription factors that can bind to the promoter sequences of the beta globin gene are only expressed in these cells. Tissue-specific transcription factors also ensure that mutations in these factors may impair only the function of...
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The escape velocity of an object is defined as the minimum initial velocity that it requires to escape the surface of another object to which it is gravitationally bound and never to return. For example, what would be the minimum velocity at which a satellite should be launched from the Earth's surface such that it just escapes the Earth's gravitational field?
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To escape the Earth's gravity, an object near the top of the atmosphere at an altitude of 100 km must travel away from Earth at 11.1 km/s. This speed is called the escape velocity. The temperature at which gas molecules attain the rms speed, which is equal to the escape velocity, can be estimated by using the equation for the average kinetic energy of the gas molecules. According to the kinetic theory of gas, the average kinetic energy of the gas molecules is proportional to its...
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Transcription elongation is a dynamic process that alters depending upon the sequence heterogeneity of the DNA being transcribed. Hence, it is not surprising that the elongation complex's composition also varies along the way while transcribing a gene.
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Related Experiment Video

Updated: Jan 25, 2026

Depletion of Specific Cell Populations by Complement Depletion
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Enterococcus faecalis Escapes Complement-Mediated Killing via Recruitment of Complement Factor H.

Youssif M Ali1,2, Robert B Sim3, Wilhelm Schwaeble2

  • 1Department of Microbiology and Immunology, Faculty of Pharmacy, Mansoura University, Egypt.

The Journal of Infectious Diseases
|May 7, 2019
PubMed
Summary
This summary is machine-generated.

Enterococcus faecalis bloodstream infections are common in critically ill patients. This study shows E. faecalis evades complement-mediated phagocytosis by binding Factor H, hindering the alternative pathway.

Keywords:
Enterococcus faecalisFactor Hcomplement system

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Area of Science:

  • Immunology
  • Microbiology
  • Infectious Diseases

Background:

  • Enterococcus faecalis is a major cause of bloodstream infections in critically ill patients.
  • The complement system, activated via classical (CP), lectin (LP), or alternative pathways (AP), is crucial for clearing bacteria like E. faecalis.

Purpose of the Study:

  • To investigate the mechanisms by which E. faecalis interacts with the complement system.
  • To understand how E. faecalis evades immune responses during infection.

Main Methods:

  • A mouse model of enterococcus peritonitis was used.
  • Mice were treated with anti-Factor H (FH) antibodies or isotype control before challenge with E. faecalis.
  • Bacterial burden in blood and organs was assessed.

Main Results:

  • Complement recognition molecules C1q, CL-11, and ficolin-A bind E. faecalis, activating the CP and LP.
  • E. faecalis recruits FH to its surface, effectively evading the AP.
  • Significant C3b deposition occurred via CP and LP, but not AP.

Conclusions:

  • E. faecalis actively avoids complement-mediated phagocytosis by the AP.
  • The bacterium sequesters host Factor H to inhibit the AP, contributing to its pathogenicity.