Within the field of mitochondrial DNA (mtDNA) analysis, heteroplasmy is a widely-recognized and yet poorly-understood event. Heteroplasmy is defined as the presence of more than one mitochondrial genome within a tissue sample from a single individual, such that the mtDNA sequence shows the presence of a mixed base or regions of homologous bases that vary in length. Due to the highly conserved nature of the mitochondrial genome, these heteroplasmic events occur at a variety of well-documented hotspots, a majority of which occur within the hypervariable control region that flanks the origin of replication. This control region is the same area that is tested in forensic mtDNA analysis, and is the most useful for establishing the link between evidentiary samples and maternally-related individuals due to the polymorphisms that accumulate in this region. However, when heteroplasmic events are uncovered in forensic mtDNA analysis, issues arise due to the lack of clear understanding of the origin of heteroplasmy. The occurrence of mtDNA heteroplasmy between different tissues within a single individual has been well-established, and heteroplasmic events have been shown to increase with age. However, what is presently unclear is whether or not mtDNA heteroplasmy exists within a single cell when heteroplasmy is present within a tissue. In this regard, three possibilities exist; 1) a single cell contains a solitary pool of mtDNA genomes (defined as homoplastic), and heteroplasmy exists as a mixture of different homoplastic cells within tissue, 2) a single cell contains a mixture of multiple mtDNA genomes, and heteroplasmy is present within a single cell, or 3) heteroplasmic tissue contains a mixture of homoplastic and heteroplasmic cells due to random cellular distribution throughout the tissue. To investigate this question, laser dissection microscopy will be used to isolate individual cells from a tissue sample with known mtDNA heteroplasmy. Typing of single nucleotide polymorphisms at specific hotspots within the HVI region will then be done to detect possible mtDNA heteroplasmy within a single cell.
|Commitee:||Kobilinsky, Lawrence, Prinz, Mechthild, Schmidt-Glenewinkel, Thomas, Umback, Noelle|
|School:||City University of New York|
|School Location:||United States -- New York|
|Source:||DAI-B 74/03(E), Dissertation Abstracts International|
|Subjects:||Molecular biology, Biochemistry|
|Keywords:||Forensics, Heteroplasmy, Hypervariable region I, Laser dissection microscopy, Mitochondrial DNA, Single nucleotide polymorphism|
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