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Gene amplification in Entamoeba histolytica
M Báez-Camargo1, R Gharaibeh, A M Riverón
1Department of Experimental Pathology, CINVESTAV, México, Mexico.
Invasion & Metastasis
|January 1, 1996
Summary
Entamoeba histolytica, a cause of amebiasis, shows DNA amplification similar to cancer cells. Researchers observed unique DNA structures, proposing an "onion skin" model for this gene amplification process.
Area of Science:
- Molecular Biology
- Parasitology
- Genetics
Background:
- Entamoeba histolytica is the protozoan parasite causing human amebiasis.
- Unscheduled DNA amplification is a known phenomenon in transformed mammalian cells.
Purpose of the Study:
- To investigate DNA amplification in Entamoeba histolytica.
- To characterize the molecular events and structures involved in DNA amplification in this protozoan.
Main Methods:
- Transmission electron microscopy (TEM) was used to visualize DNA structures.
- Analysis of DNA content in different clones of E. histolytica (strain HM1:IMSS).
- Pulse field gel electrophoresis (PFGE) to separate DNA fragments.
Main Results:
- TEM revealed linear, circular, and concentric circular DNA molecules indicative of DNA amplification.
- Observed events include loop formation via recombination, replication bubbles, and nested circles.
- Multicircle complexes formed without distant DNA recombination.
- Clones showed varying DNA content, with differences in rDNA gene copy numbers between parental and daughter clones (A and C2).
Conclusions:
- Entamoeba histolytica exhibits DNA amplification mechanisms analogous to transformed mammalian cells.
- A novel "onion skin" model is proposed to explain gene amplification in E. histolytica based on observed TEM data.