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Open Access Research

The genome and transcriptome of the enteric parasite Entamoeba invadens, a model for encystation

Gretchen M Ehrenkaufer1, Gareth D Weedall2, Daryl Williams2, Hernan A Lorenzi3, Elisabet Caler3, Neil Hall24* and Upinder Singh15*

Author affiliations

1 Division of Infectious Diseases, Department of Internal Medicine, Stanford University, Stanford, California, 94305, USA

2 Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool, UK

3 J Craig Venter Institute, Rockville, Maryland, L697ZB USA

4 Faculty of Science, King Abdulaziz University, Jeddah, 21589, SA

5 Department of Microbiology and Immunology, Stanford University, Stanford, California, 94305, USA

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Citation and License

Genome Biology 2013, 14:R77  doi:10.1186/gb-2013-14-7-r77

Published: 26 July 2013

Abstract

Background

Several eukaryotic parasites form cysts that transmit infection. The process is found in diverse organisms such as Toxoplasma, Giardia, and nematodes. In Entamoeba histolytica this process cannot be induced in vitro, making it difficult to study. In Entamoeba invadens, stage conversion can be induced, but its utility as a model system to study developmental biology has been limited by a lack of genomic resources. We carried out genome and transcriptome sequencing of E. invadens to identify molecular processes involved in stage conversion.

Results

We report the sequencing and assembly of the E. invadens genome and use whole transcriptome sequencing to characterize changes in gene expression during encystation and excystation. The E. invadens genome is larger than that of E. histolytica, apparently largely due to expansion of intergenic regions; overall gene number and the machinery for gene regulation are conserved between the species. Over half the genes are regulated during the switch between morphological forms and a key signaling molecule, phospholipase D, appears to regulate encystation. We provide evidence for the occurrence of meiosis during encystation, suggesting that stage conversion may play a key role in recombination between strains.

Conclusions

Our analysis demonstrates that a number of core processes are common to encystation between distantly related parasites, including meiosis, lipid signaling and RNA modification. These data provide a foundation for understanding the developmental cascade in the important human pathogen E. histolytica and highlight conserved processes more widely relevant in enteric pathogens.