TY  - JOUR
A1  - Khan, Asis
A1  - Böhme, Ulrike
A1  - Kelly, Krystyna A.
A1  - Adlem, Ellen
A1  - Brooks, Karen
A1  - Simmonds, Mark
A1  - Mungall, Karen
A1  - Quail, Michael A.
A1  - Arrowsmith, Claire
A1  - Chillingworth, Tracey
A1  - Churcher, Carol
A1  - Harris, David
A1  - Collins, Matthew
A1  - Fosker, Nigel
A1  - Fraser, Audrey
A1  - Hance, Zahra
A1  - Jagels, Kay
A1  - Moule, Sharon
A1  - Murphy, Lee
A1  - O'Neil, Susan
A1  - Rajandream, Marie-Adele
A1  - Saunders, David
A1  - Seeger, Kathy
A1  - Whitehead, Sally
A1  - Mayr, Thomas
A1  - Xuan, Xuenan
A1  - Watanabe, Junichi
A1  - Suzuki, Yutaka
A1  - Wakaguri, Hiroyuki
A1  - Sugano, Sumio
A1  - Sugimoto, Chihiro
A1  - Paulsen, Ian
A1  - Mackey, Aaron J.
A1  - Roos, David S.
A1  - Hall, Neil
A1  - Berriman, Matthew
A1  - Barrell, Bart
A1  - Sibley, L. David
A1  - Ajioka, James W.
T1  - Common inheritance of chromosome Ia associated with clonal expansion of Toxoplasma gondii
Y1  - 2006/09/01 
JF  - Genome Research 
JO  - Genome Research 
SP  - 1119 
EP  - 1125 
DO  - 10.1101/gr.5318106 
VL  - 16 
IS  - 9 
UR  - http://genome.cshlp.org/content/16/9/1119.abstract 
N2  - 
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.
 
ER  -