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Biological evidence of genetic exchange in Entamoeba histolytica
P G Sargeaunt1, T F Jackson, S R Wiffen
1Department of Medical Protozoology, London School of Hygiene and Tropical Medicine, UK.
Abstract:
The demonstration of a new zymodeme of Entamoeba histolytica produced in culture from cloned isolates suggested possible genetic exchange in this parasite. We have attempted to substantiate that finding by using rats as biological hosts. Clones were made from 3 separate isolates of E. histolytica, each established in culture from liver pus or faeces. After enzyme characterization these clones, of zymodemes II, XIV and XIX, were paired in each of the 3 possible combinations and the mixtures injected into the caecum of rats. Clones of new or hybrid zymodemes were produced as well as the original parents, with one exception, the mixture of XIV and XIX, from which only one of the parents was recovered. The hybrids produced included zymodeme XX, observed previously, and zymodeme XI, a naturally occurring zymodeme that has in the past been recovered only from subjects with invasive amoebiasis.
Insights
Genetic exchange in Entamoeba histolytica was investigated using rat models. Researchers found evidence of hybrid zymodemes, suggesting genetic recombination occurs in this parasitic organism.
Area of Science:
- Medical Parasitology
- Molecular Biology
- Genetics
Background:
- Cloned isolates of Entamoeba histolytica produced a new zymodeme, suggesting potential genetic exchange.
- Entamoeba histolytica is an intestinal parasite that causes amoebiasis.
Purpose of the Study:
- To substantiate the possibility of genetic exchange in Entamoeba histolytica.
- To investigate the genetic recombination of Entamoeba histolytica zymodemes in a biological host.
Main Methods:
- Cloned isolates of Entamoeba histolytica (zymodemes II, XIV, XIX) were generated from liver pus or faeces.
- Paired combinations of these clones were injected into the caecum of rats.
- Enzyme characterization was used to identify resulting zymodemes.
Main Results:
- New and hybrid zymodemes were produced in rats, alongside the original parent zymodemes.
- A notable exception was the mixture of zymodemes XIV and XIX, from which only one parent was recovered.
- Hybrid zymodemes included previously observed zymodeme XX and naturally occurring zymodeme XI.
Conclusions:
- The study provides evidence for genetic exchange and recombination in Entamoeba histolytica within a biological host.
- The recovery of zymodeme XI, typically associated with invasive amoebiasis, from experimental hybrids warrants further investigation.
- These findings contribute to understanding the genetic diversity and evolution of Entamoeba histolytica.