title: The apicoplast genomes of two taxonomic units of Babesia from sheep.
abstract: The apicoplast (ap) is a unique, non-photosynthetic organelle found in most apicomplexan parasites. Due to the essential roles that this organelle has, it has been widely considered as target for drugs against diseases caused by apicomplexans. Exploring the ap genomes of such parasites would provide a better understanding of their systematics and their basic molecular biology for therapeutics. However, there is limited information available on the ap genomes of apicomplexan parasites. In the present study, the ap genomes of two operational taxonomic units of Babesia (known as Babesia sp. Lintan [Bl] and Babesia sp. Xinjiang [Bx]) from sheep were sequenced, assembled and annotated using a massive parallel sequencing-based approach. Then, the gene content and gene order in these ap genomes (∼30.7kb in size) were defined and compared, and the genetic differences were assessed. In addition, a phylogenetic analysis of ap genomic data sets was carried out to assess the relationships of these taxonomic units with other apicomplexan parasites for which complete ap genomic data sets were publicly available. The results showed that the ap genomes of Bl and Bx encode 59 and 57 genes, respectively, including 2 ribosomal RNA genes, 25 transfer RNA genes and 30-32 protein-encoding genes, being similar in content to those of Babesia bovis and B. orientalis. Ap gene regions that might serve as markers for future epidemiological and population genetic studies of Babesia species were identified. Using sequence data for a subset of six protein-encoding genes, a close relationship of Bl and Bx with Babesia bovis from cattle and B. orientalis from water buffalo was inferred. Although the focus of the present study was on Babesia, we propose that the present sequencing-bioinformatic approach should be applicable to organellar genomes of a wide range of apicomplexans of veterinary importance.
authors.affiliation: State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Gansu, PR China; Faculty of Veterinary Science, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Gansu, PR China.
authors.forename: Guiquan
authors.initials: G
authors.lastname: Guan
authors.affiliation: Faculty of Veterinary Science, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Pasi K
authors.initials: PK
authors.lastname: Korhonen
authors.affiliation: Faculty of Veterinary Science, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Anson V
authors.initials: AV
authors.lastname: Koehler
authors.affiliation: Faculty of Veterinary Science, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Ross S
authors.initials: RS
authors.lastname: Hall
authors.affiliation: Faculty of Veterinary Science, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Neil D
authors.initials: ND
authors.lastname: Young
authors.affiliation: State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Gansu, PR China. Electronic address: yinhong@caas.cn.
authors.forename: Hong
authors.initials: H
authors.lastname: Yin
authors.affiliation: Faculty of Veterinary Science, The University of Melbourne, Parkville, Victoria, Australia. Electronic address: robinbg@unimelb.edu.au.
authors.forename: Robin B
authors.initials: RB
authors.lastname: Gasser
mesh_terms: D000818:Animals; D063546:Apicoplasts / Q000235:genetics*; D001403:Babesia / Q000235:genetics*; D016054:DNA, Protozoan / Q000235:genetics; D018503:Genome, Protozoan / Q000235:genetics*; D012756:Sheep / Q000469:parasitology
chemical_list: D016054:DNA, Protozoan
keywords: Apicoplast genome; Babesia/babesiosis; Bioinformatics; Illumina sequencing; Relationships; Therapeutics