Molecular phylogenetic analysis inHammondia-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.

Molecular phylogeny of Toxoplasmatinae: comparison between inferences based on mitochondrial and apicoplast genetic sequences

“…This is a parasite isolated from a rodent (Akodon montensis) that is native to Brazil and was obtained as previously described (DUBEY et al, 2003b). DNA from the Neospora hughesi Oregon isolate (DUBEY et al, 2001), Hammondia hammondi (isolate 300) and two genetically divergent lineages of Hammondia heydorni (isolates 376 and BR) were obtained as described elsewhere (MONTEIRO et al, 2007).…”

“…The aim of this paper was to demonstrate the suitability of these molecular markers for studying the genetic variability and phylogenetic relationships among members of the Toxoplasmatinae subfamily. Phylogenies within Toxoplasmatinae have been greatly investigated with other molecular markers (MUGRIDGE et al, 1999;ELLIS et al, 1999;MONTEIRO et al, 2007;SOARES et al, 2011).…”

Prospects for elucidating the phylogeny of the Apicomplexa

“…Clearly, there will be some major re-definition of taxonomic groups throughout the Apicomplexa. Furthermore, even some smaller genera are rendered paraphyletic by the recognition of economically important pathogens as separate genera; for example, the relationship between Hammondia and both Neospora caninum and Toxoplasma gondii (Monteiro et al, 2007). This can lead to serious conflicts between the scientific requirements of classification and the more pragmatic requirements of end-users ( Slapeta et al, 2002;Pérez-Tris et al, 2005 Perkins et al, 2007).…”

“…However, they also occur when there is a distant outgroup, as the branch connecting the ingroup and outgroup will be much longer than the within-ingroup branches (e.g. Schrenzel et al, 2005;Monteiro et al, 2007). It is worth noting that the common practice of performing multiple analyses of the same data set (e.g.…”

“…Alternatively, the phenotypic data might have been over-simplified, by combining several independent characters into one complex character; or the data set may have been incomplete or inaccurate. Within the Apicomplexa, molecular data indicate that Hammondia hammondi is closely related to Toxoplasma gondii while Hammondia heydorni is related to Neospora caninum (Monteiro et al, 2007). Therefore, the characters upon which these three genera were originally based need to be re-evaluated, including the location of the tissue cysts (brain versus muscles) and the type of heteroxeny (facultative versus obligate); and both of these characters have been successfully re-evaluated.…”