Two extra chromosomal genomes of Leucocytozoon caulleryi; complete nucleotide sequences of the mitochondrial genome and existence of the apicoplast genome

Abstract

We analyzed extra chromosomal genomes of avian blood protozoa, Leucocytozoon caulleryi. One of the genomes, the mitochondrial genome was completely sequenced resulting 5,959 bp in length. This genome contained the identical gene organization and contents to that of other avian blood protozoa previously analyzed: three functional genes for cytochrome c oxidase subunit I, III, and cytochrome b with following sets of discontinuous and scrambled 15 ribosomal subunit RNA genes. In addition, the mitochondrial genome was estimated to have the tandem repeated structure as well as previously found in avian Plasmodium species. Furthermore, we found partial gene sequences of apicoplast DNA, another extra chromosomal genome, from L. caulleryi. These sequences were estimated as partial caseinolytic protease C and elongation factor Tu A genes. This report is the first description of two extra chromosomal genomes of L. caulleryi.

Characterization of the complete mitochondrial genomes of five Eimeria species from domestic chickens

“…Previous studies of the mt genomes of some other Apicomplexa parasites have revealed that the putative transcriptional direction of 3 protein-coding genes is usually different. For example, in L. caulleryi, Plasmodium gallinaceum, P. juxtanucleare and Theileria equi, the putative transcriptional direction of the cox3 gene was opposite to other two protein-coding genes (Omori et al, 2007;Omori et al, 2008;Hikosaka et al, 2010a,b), but in the present study, the putative direction of translation for 3 genes (cox1, cox3 and cytb) was the same in all six Eimeria species. Phylogenetic analyses of six Eimeria species with related Apicomplexa parasites based on concatenated mitochondrial nucleotide sequences of the cytb and cox1 genes revealed two distinct groups: the Haemosporina/Eimeriina clade and the Piroplasmida clade with high statistical support (Fig.…”

“…All of the 3 protein-coding genes (cox1, cox3 and cytb) have the same and complete termination codon (TAA), which was not consistent with the arrangement in the mt genomes of some other Apicomplexa parasites for which an abbreviated stop codon, such as TA or T were used. Furthermore, the cox1 and cox3 of L. caulleryi had a nonstandard initiation codon CTA and TTG, respectively (Omori et al, 2008). Previous studies of the mt genomes of some other Apicomplexa parasites have revealed that the putative transcriptional direction of 3 protein-coding genes is usually different.…”

“…The nucleotide sequences and inferred amino acid sequences for each of the 3 mt proteins of Eimeria spp. were compared with that of Leucocytozoon caulleryi (Omori et al, 2008). The identity of the nucleotide and amino acid sequences among the six Eimeria species were 88.3-98.5% and 91.3-99.1%, respectively.…”

“…Sequences were assembled manually with other mt genome sequences available from other apicomplexans (Feagin et al, 1992(Feagin et al, , 1997Jongwutiwes et al, 2005;Omori et al, 2007;Omori et al, 2008;Hikosaka et al, 2010a,b) using Clustal X 1.83 (Thompson et al, 1997). Ribosomal RNA genes and protein-coding genes were identified by comparison with the mt genome of E. tenella reported recently (Hikosaka et al, 2010b).…”

“…To date, quite a number of complete mitochondrial DNA sequences have been published for metazoan organisms, including vertebrates (Hu et al, 2002;Park et al, 2007). Although complete mt genome sequences are available for a range of helminths, such as Schistosoma, Echinococcus and Toxocara (Nakao et al, 2002;Le et al, 2002;Littlewood et al, 2006;Li et al, 2008a), only limited complete mtDNA sequences have been published for parasitic protozoons of socioeconomic importance (Feagin et al, 1992;Kairo et al, 1994;Feagin et al, 1997;Jongwutiwes et al, 2005;Omori et al, 2007;Omori et al, 2008;Perkins, 2008;Hikosaka et al, 2010a;Iwagami et al, 2010). In particular, the complete mt genomes of the species in the sub-order Eimeriina are not available except for E. tenella (Hikosaka et al, 2010b).…”