@article{Khan01092006,
author = {Khan, Asis and Böhme, Ulrike and Kelly, Krystyna A. and Adlem, Ellen and Brooks, Karen and Simmonds, Mark and Mungall, Karen and Quail, Michael A. and Arrowsmith, Claire and Chillingworth, Tracey and Churcher, Carol and Harris, David and Collins, Matthew and Fosker, Nigel and Fraser, Audrey and Hance, Zahra and Jagels, Kay and Moule, Sharon and Murphy, Lee and O'Neil, Susan and Rajandream, Marie-Adele and Saunders, David and Seeger, Kathy and Whitehead, Sally and Mayr, Thomas and Xuan, Xuenan and Watanabe, Junichi and Suzuki, Yutaka and Wakaguri, Hiroyuki and Sugano, Sumio and Sugimoto, Chihiro and Paulsen, Ian and Mackey, Aaron J. and Roos, David S. and Hall, Neil and Berriman, Matthew and Barrell, Bart and Sibley, L. David and Ajioka, James W.}, 
title = {Common inheritance of chromosome Ia associated with clonal expansion of Toxoplasma gondii},
volume = {16}, 
number = {9}, 
pages = {1119-1125}, 
year = {2006}, 
doi = {10.1101/gr.5318106}, 
abstract ={
Toxoplasma gondii is a globally distributed protozoan parasite that can infect virtually all warm-blooded animals and humans. Despite the existence of a sexual phase in the life cycle, T. gondii has an unusual population structure dominated by three clonal lineages that predominate in North America and Europe, (Types I, II, and III). These lineages were founded by common ancestors ~10,000 yr ago. The recent origin and widespread distribution of the clonal lineages is attributed to the circumvention of the sexual cycle by a new mode of transmission—asexual transmission between intermediate hosts. Asexual transmission appears to be multigenic and although the specific genes mediating this trait are unknown, it is predicted that all members of the clonal lineages should share the same alleles. Genetic mapping studies suggested that chromosome Ia was unusually monomorphic compared with the rest of the genome. To investigate this further, we sequenced chromosome Ia and chromosome Ib in the Type I strain, RH, and the Type II strain, ME49. Comparative genome analyses of the two chromosomal sequences revealed that the same copy of chromosome Ia was inherited in each lineage, whereas chromosome Ib maintained the same high frequency of between-strain polymorphism as the rest of the genome. Sampling of chromosome Ia sequence in seven additional representative strains from the three clonal lineages supports a monomorphic inheritance, which is unique within the genome. Taken together, our observations implicate a specific combination of alleles on chromosome Ia in the recent origin and widespread success of the clonal lineages of T. gondii.
}, 
URL = {http://genome.cshlp.org/content/16/9/1119.abstract}, 
eprint = {http://genome.cshlp.org/content/16/9/1119.full.pdf+html}, 
journal = {Genome Research} 
}