The discovery of fetal-derived circulating nucleic acids in maternal plasma has opened up new opportunities for non-invasive prenatal diagnosis. This non-invasive means of obtaining fetal genetic materials is safer than invasive tissue-sampling procedures, which are associated with a small but finite chance of fetal loss. Over the past decade, the detection of fetal DNA in maternal plasma has evolved from dependency on discriminative genetic markers, such as Y-chromosome-specific loci or paternally-inherited polymorphisms, to detection of circulating RNA, fetal-specific methylation or by massively parallel sequencing. Fetal-specific methylation, or fetal epigenetic marker, does not require prior knowledge of the sex or polymorphic status of the fetus and thus can be applied in essentially all pergnancies. This thesis focuses on the development of this kind of marker for non-invasive monitoring and detection of pre-eclampsia and fetal aneuploidies. / The first part of this thesis describes the use of a reported fetal epigenetic marker, RASISF1A, to measure the fetal DNA concentrations in maternal plasma of pre-eclamptic subjects versus gestational-age-matched controls. The second part of this thesis describes a systematic search for potential epigenetic markers for pre-eclampsia and the second commonest fetal aneuploidy, trisomy 18. Numerous approaches for methylation profiling are described, such as methylation-specific polymerase chain reaction (MSP), bisulfite sequencing, a mass spectrometry-based platform (the Epityper assay), and methylated DNA immunoprecipitation coupled with tiling array analysis (MeDIP-chip). Using MeDIP-chip, I selected the most promising fetal epigenetic markers on chromosome 18, and further characterised their detection in maternal plasma. The final part of this thesis describes an approach called epigenetic-genetic (EGG) chromosome dosage for the detection of trisomy 18 based on those markers. I have demonstrated that it is feasible to detect fetal trisomy 18 by analysing maternal plasma in as early as the first trimester. / This thesis illustrates different strategies for methylation profiling and presented two examples of applying DNA methylation for the non-invasive prenatal assessment of pregnancy-associated disorders and fetal chromosomal aneuploidies. I envision that a similar strategy could be developed for other pregnancy-related diseases to broaden the application of epigenetic markers in non-invasive prenatal diagnosis. / Tsui, Wai Yi. / Adviser: Y.M. Dennis Lo. / Source: Dissertation Abstracts International, Volume: 73-02, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 198-221). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Giardia intestinalis is a parasitic protist that causes one of the most common diarrheal disease of parasite origin. The cell of Giardia contains two nuclei with unknown number of chromosomes until recently. Karyotype was determined five years ago using conventional cytogenetic method by Tůmová and collaborators. In my work, I assessed karyotype of four isolates, six lines and three clonal lines by the same method. It was confirmed, that two nuclei within one cell could differ in chromosome number, the differences found were 1, 2 or 6 chromosomes. Aneuploid number of chromosomes was found too. In case that both nuclei within single cell contained the same number of chromosomes, there were 10 chromosomes indentified in each nucleus. It was also revealed, that karyotype is not specific feature for different genetic groups (in this work assemblages A and E). Karyotype can be different even among lines and clonal populations derived from the same isolate. Changes in karyotype in the course of in vitro cultivation were detected within three populations. Results are discussed in relation to known facts.

Genomic integrity in mouse embryonic and induced pluripotent stem cells can be compromised by factors such as extended time in culture and cellular reprogramming. Surprising, only a few studies have thus far examined the accumulation of chromosomal imbalances in mouse pluripotent populations upon prolonged propagation in vitro. It is presumed that specific recurring genetic changes can confer selective growth advantage and resistance to apoptosis and/or differentiation to the affected cells, although the genes that drive these processes remain elusive. The presence of these changes in published studies can confound the analysis of the data and hinder the reproducibility of the results. At the transcriptional level, aneuploidy manifests as large chromosomal regions of aberrant gene expression. This thesis presents a method to identify these regions in large-scale datasets and interrogate for recurrent patterns. The present analysis shows that over half of the 315 mouse pluripotent samples examined carry whole or partial-chromosome spanning clusters of aberrant transcription. Furthermore, there are common gene expression changes across samples with any type of predicted aneuploidy and samples with chromosome-specific aberrations. These transcriptional signatures have been used to train classification models which can predict aneuploid samples with over 90% accuracy. This is an important step towards the development of a low-cost and reliable transcriptional validation assay for the presence of aneuploidy.

Abstract not available

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references (leaves 117-121). Also available on the Internet.

Dissertation (Ph.D.)--University of Toledo, 2009. / "In partial fulfillment of the requirements for the degree of Doctor of Philosophy in Biomedical Science." Title from title page of PDF document. Bibliography: p. 87-96.

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references (leaves 117-121). Also available on the Internet.

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 89-99).

No description available.

While the introduction of intracytoplasmic sperm injection (ICSI) has revolutionized the treatment of male infertility, concerns have been raised regarding the risk of chromosomal abnormalities in pregnancies derived from ICSI. Studies on sperm from infertile men have suggested that this population may produce higher rates of aneuploid sperm. Thus, we hypothesized that defects in early meiotic events may contribute to both male infertility and the production of aneuploid sperm. We used immunofluorescent techniques to observe the synapsis and recombination of chromosomes during meiosis, and fluorescent in-situ hybridization (FISH) to assess sperm aneuploidy. We analyzed testicular tissue from thirty-one men (10 fertile and 21 infertile men). We observed that ~36% (5/14) of men with impaired spermatogenesis displayed reduced genome-wide recombination. When all men were pooled, we observed an inverse correlation between the frequency of sex chromosome recombination and XY disomy in the sperm. We combined immunofluorescent and FISH techniques to study recombination patterns on chromosomes 13, 18 and 21 in fifteen men (5 fertile and 10 infertile men). Four of the infertile men displayed altered recombination distributions on at least one of the chromosome arms studied. Finally, we examined early meiotic events in two biopsies from an azoospermic t(8;13) carrier. While global recombination rates were not altered, recombination frequencies were reduced specifically on the rearranged chromosomes. Asynapsed quadrivalents were observed in 90% and 87% of pachytene nuclei from the first and second biopsies, respectively, and were frequently associated with the sex chromosomes. BRCA1 and γH2AX, two proteins implicated in meiotic sex chromosome inactivation, localized along asynapsed regions regardless of whether or not they were associated with the sex chromosomes, suggesting that regions of autosomal chromosomes that fail to synapse undergo transcriptional silencing in humans. In summary, we observed that a subset of infertile men display alterations in the number and position of meiotic crossovers, which may contribute to both infertility and an increased risk of sperm aneuploidy. The fidelity of synapsis is also a critical factor in determining the outcome of gametogenesis in humans, as the transcriptional inactivation of asynapsed regions may silence meiotic genes, leading to meiotic arrest and infertility.