Evolution of parasitism in the Apicomplexa: the genome sequence of Colpodella sp.-sc-2010-05-25
Evolution of parasitism in the Apicomplexa: the genome sequence of Colpodella sp.
Colpodella spp. are free-living, predatory flagellates. They are the closest known non-parasitic relatives of the Apicomplexa, which includes most notably the malaria parasites Plasmodium spp., but also various other parasites of Humans and livestock such as Theileria spp., Babesia spp., Toxoplasma gondii, Neospora caninum, Eimeria spp. Sarcocystis spp. and Cryptosporidium spp, as well as the Gregarines. With reference genomes in place for most of these parasitic Apicomplexa, a Colpodella genome sequence presents an opportunity to compare the parasites with a non-parasitic relative, and to compare the parasites with each other in the presence of an appropriate outgroup. Essentially, Colpodella offers us the best model of what the non-parasitic ancestor of extant Apicomplexa was like. It will enable us to better understand the similarities and differences between the parasite genomes, in terms of gene gain, loss and modification in their last common ancestor, i.e., at the origin of parasitism.. This data is part of a pre-publication release. For information on the proper use of pre-publication data shared by the Wellcome Trust Sanger Institute (including details of any publication moratoria), please see http://www.sanger.ac.uk/datasharing/
The purpose of a Colpodella genome sequence is to provide an 'outgroup' for comparative genomic analyses. Phylogenetic analysis has shown that the Colpodellidae are the natural sister clade to Apicomplexa sensu stricto, including the Gregarines (Kuvardina et al. 2002, Leander et al. 2003). As such, a Colpodella genome sequence will provide a model of the ancestral Apicomplexan to distinguish those derived parts of the parasite genomes (i.e., unique Apicomplexan adaptations) from those which are a legacy of the free-living ancestor. This objective can be resolved into three principal comparative issues: (i) Evolution of parasitism; to understand how the process of becoming parasitic changed the genome of the ancestral Apicomplexan in terms of innovation and loss of genomic repertoire; (ii) Origins of Apicomplexan adaptations; to identify the homologs encoding specialized cellular organelles and multi-copy protein families characteristic of Apicomplexan parasites in the non-parasite, and so better understand the homology between parasites. (iii) Apicomplexan disease; understanding how human and animal Apicomplexan parasites acquired their distinct pathological strategies. The WTSI is undertaking complete genome sequencing of genomic DNA from a single cell of Colpodella sp. ATCC50594 using Illumina technology. We intend to supplement this with whole-cell RNA sequencing, again using single-cell preparation and the Illumina platform.