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DNA Barcoding of Apicomplexa: Mitochondrial Evolution across the Phylum

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dc.contributor.advisor Barta, R. John Ogedengbe, Mosunmola Elina 2015-08-24T18:59:18Z 2015-08-24T18:59:18Z 2015-08 2015-07-28 2015-08-24
dc.description.abstract The parasitic phylum Apicomplexa contains thousands of species identified historically using morphology, morphometrics and host/tissue associations. Diagnostic stages of apicomplexan parasites are difficult to identify morphologically; thus, classical methods were supplemented with molecular techniques. Broadly applicable molecular markers that could support species identification and phylogenetic studies were sorely needed. “DNA barcoding” utilizes short, standardized DNA sequence obtained from the mitochondrial (mt) cytochrome c oxidase subunit I (COI) gene. Lack of PCR primers suitable for apicomplexan parasites limited mt COI use. Research reported herein tested utility of mt COI sequences for identification and phylogenetics of tissue (i.e. Sarcocystidae), eimeriid (e.g. Eimeriidae, Lankesterellidae) and adeleid coccidia (i.e. Hepatozoon and other haemogregarines). Degenerate primers of broad specificities generated mt COI DNA barcodes that, with few exceptions (notably Cystoisospora spp.), identified any enteric (e.g. Isospora, Cyclospora, Eimeria) or tissue (e.g. Toxoplasma, Hammondia, Sarcocystis) coccidium. The mt COI locus is recommended as a suitable DNA barcoding target for coccidian parasites of veterinary and zoonotic importance. Complete mt genomes of >20 eimeriid and adeleid coccidia were sequenced. More 17 species representing 6 genera of eimeriid (Eimeria, Isospora, Caryospora, Cyclospora, Lankesterella) and adeleid coccidia (Hepatozoon catesbianae) were sequenced. Eimeriid mt genomes (~ 6,000 bases) are predominantly circular-mapping possessing 3 protein-coding genes (CDS) and rDNA fragments in conserved order; only Cyclospora cayetanensis, a human pathogen, had a linear mt genome possessing a 5´-terminal hairpin and 3´-terminus with telomere-like repetitive elements. Gene orders and directions were largely conserved within, but divergent between, major groups of apicomplexan parasites. Phylogenetic analyses using mt CDS sequences (i.e. partial mt COI or concatenated CDS sequences) with or without nuclear 18S rDNA sequences suggest combined nu 18S rDNA and mt COI sequences (analysed using partitioned data with suitable nucleotide substitution models for each partition) provide robust evolutionary hypotheses for these parasites. Taxonomic solutions addressing paraphylies identified in phylogenetic analyses were proposed. The mt genomes of Apicomplexa possess divergent structures and gene arrangements. Mitochondrial COI sequences were concluded to be better species-level markers than the widely used nu 18S rDNA locus; mt COI sequences had utility in both diagnostic and phylogenetic studies. en_US
dc.description.sponsorship OVC PhD Scholarship en_US
dc.language.iso en en_US
dc.rights Attribution-NonCommercial-NoDerivs 2.5 Canada *
dc.rights.uri *
dc.subject Parasites en_US
dc.subject Phylum Apicomplexa en_US
dc.subject Coccidia en_US
dc.subject Eimeriidae en_US
dc.subject Sarcocystidae en_US
dc.subject Morphology en_US
dc.subject Morphometrics en_US
dc.subject DNA Barcoding en_US
dc.subject Cytochrome c oxidase subunit 1 en_US
dc.subject nuclear 18S rDNA en_US
dc.subject Identification en_US
dc.subject Delimitation en_US
dc.subject Genetic marker en_US
dc.subject Mitochondrial genome en_US
dc.subject Sequencing en_US
dc.subject Cloning en_US
dc.subject Diversity en_US
dc.subject Mini genomes en_US
dc.subject Circular mapping genomes en_US
dc.subject Linear concatemer en_US
dc.subject Genome rearrangements en_US
dc.subject Molecular Phylogenetics en_US
dc.subject Monophyly en_US
dc.subject Paraphyly en_US
dc.subject Taxonomy en_US
dc.subject Evolution en_US
dc.title DNA Barcoding of Apicomplexa: Mitochondrial Evolution across the Phylum en_US
dc.type Thesis en_US Pathobiology en_US Doctor of Philosophy en_US Department of Pathobiology en_US
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Attribution-NonCommercial-NoDerivs 2.5 Canada Except where otherwise noted, this item's license is described as Attribution-NonCommercial-NoDerivs 2.5 Canada