title: Molecular phylogenetic analysis in Hammondia-like organisms based on partial Hsp70 coding sequences.
abstract: The 70 kDa heat-shock protein (Hsp70) sequences are considered one of the most conserved proteins in all domains of life from Archaea to eukaryotes. Hammondia heydorni, H. hammondi, Toxoplasma gondii, Neospora hughesi and N. caninum (Hammondia-like organisms) are closely related tissue cyst-forming coccidians that belong to the subfamily Toxoplasmatinae. The phylogenetic reconstruction using cytoplasmic Hsp70 coding genes of Hammondia-like organisms revealed the genetic sequences of T. gondii, Neospora spp. and H. heydorni to possess similar levels of evolutionary distance. In addition, at least 2 distinct genetic groups could be recognized among the H. heydorni isolates. Such results are in agreement with those obtained with internal transcribed spacer-1 rDNA (ITS-1) sequences. In order to compare the nucleotide diversity among different taxonomic levels within Apicomplexa, Hsp70 coding sequences of the following apicomplexan organisms were included in this study: Cryptosporidium, Theileria, Babesia, Plasmodium and Cyclospora. Such analysis revealed the Hammondia-like organism to be the lowest divergent group when compared to other groups within the phylum Apicomplexa. In conclusion, the Hsp70 coding sequences proved to be a valuable genetic marker for phylogenetic reconstruction and may constitute a good candidate to be used with other genes for species phylogeny within this group of organisms.
authors.affiliation: Departamento de Medicina Veterinária Preventiva e Saúde Animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, Av. Prof. Dr. Orlando Marques de Paiva, 87, CEP 05508-900, São Paulo, SP, Brazil.
authors.forename: R M
authors.initials: RM
authors.lastname: Monteiro
authors.forename: L J
authors.initials: LJ
authors.lastname: Richtzenhain
authors.forename: H F J
authors.initials: HF
authors.lastname: Pena
authors.forename: S L P
authors.initials: SL
authors.lastname: Souza
authors.forename: M R
authors.initials: MR
authors.lastname: Funada
authors.forename: S M
authors.initials: SM
authors.lastname: Gennari
authors.forename: J P
authors.initials: JP
authors.lastname: Dubey
authors.forename: C
authors.initials: C
authors.lastname: Sreekumar
authors.forename: L B
authors.initials: LB
authors.lastname: Keid
authors.forename: R M
authors.initials: RM
authors.lastname: Soares
mesh_terms: D000818:Animals; D001483:Base Sequence; D003044:Coccidia / Q000235:genetics*; D014644:Genetic Variation; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics*; D010802:Phylogeny
chemical_list: D018840:HSP70 Heat-Shock Proteins