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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Cytosine Methylation of an Ancient Satellite Family in the Wild Beet Beta procumbens

Schmidt, Martin, Hense, Sarah, Minoche, André E., Dohm, Juliane C., Himmelbauer, Heinz, Schmidt, Thomas, Zakrzewski, Falk 20 May 2020 (has links)
DNA methylation is an essential epigenetic feature for the regulation and maintenance of heterochromatin. Satellite DNA is a repetitive sequence component that often occurs in large arrays in heterochromatin of subtelomeric, intercalary and centromeric regions. Knowledge about the methylation status of satellite DNA is important for understanding the role of repetitive DNA in heterochromatization. In this study, we investigated the cytosine methylation of the ancient satellite family pEV in the wild beet Beta procumbens. The pEV satellite is widespread in species-specific pEV subfamilies in the genus Beta and most likely originated before the radiation of the Betoideae and Chenopodioideae. In B. procumbens , the pEV subfamily occurs abundantly and spans intercalary and centromeric regions. To uncover its cytosine methylation, we performed chromosome-wide immunostaining and bisulfite sequencing of pEV satellite repeats. We found that CG and CHG sites are highly methylated while CHH sites show only low levels of methylation. As a consequence of the low frequency of CG and CHG sites and the preferential occurrence of most cytosines in the CHH motif in pEV monomers, this satellite family displays only low levels of total cytosine methylation.
32

Methylome Analysis: From Computation Workflow Development to Implementation in a Breast Cancer Prevention Trial

Frankhouser, David E. January 2017 (has links)
No description available.
33

Untersuchung des transkriptionellen Mechanismus der Igf2- Überexpression in Patched-assoziierten Tumoren / Investigation of the transcriptional mechanism of the Igf2-overexpression in Patched-associated tumours

Bauer, Regine 02 May 2006 (has links)
No description available.
34

Establishment and maintenance of the DNA methylation pattern in the human alpha-globin cluster

Gaentzsch, Ricarda E. G. January 2013 (has links)
DNA methylation is an epigenetic modification that plays an important role in development and differentiation. The patterns of DNA methylation are largely established in early embryogenesis and maintained during development. Abnormal DNA methylation patterns have been associated with many human diseases, including cancer. Despite its importance, little is currently known about the mechanisms that determine DNA methylation patterns throughout the genome. To shed light on the molecular mechanisms that regulate DNA methylation, this study investigates whether DNA methylation patterns are established and maintained normally when human DNA is placed into a heterologous murine environment as opposed to its natural, endogenous chromosomal environment. Here, a previously generated transgenic mouse model, containing 117 kb of human DNA bearing the human α-globin cluster and all of its known regulatory elements, was analysed. The pattern of DNA methylation of the endogenous human α-globin cluster was compared with that of the transgenic cluster in the background of mouse embryonic stem cells (ESCs) and tissues. It was found that, although the normal human DNA methylation pattern was largely established and maintained in a mouse background, the region immediately around the human α-globin genes themselves is generally less methylated in mouse compared to human ESCs. It was found that regions adjacent and up to 2kb from the CpG islands (CGIs), so-called CGI shores, were unusually hypomethylated: this seems to be the result of an extension of CGIs in humanised mouse (hm) ESCs compared to human (h) ESCs. Furthermore, this hypomethylation appeared to increase during development in both erythroid and non-erythoid cells. To identify any cis-regulatory sequences responsible for the hypomethylated state of human CGI shores in the mouse, 2-4 kb human test sequences containing the CGI associated with the human α-globin 2 (α2) gene and its adjacent hypomethylated shore were re-integrated into the mouse α-globin locus via recombination-mediated cassette exchange (RMCE). Human CGI shores became hypomethylated in the context of the re-integrated test sequences, indicating that the appearance of hypomethylation is determined by the underlying human DNA sequence in the test fragments. In summary, the data presented here reveal that human CGIs become extended when placed in a mouse background leading to hypomethylation of human CGI shores in the mouse compared to the pattern of methylation at the normal endogenous human locus. These findings suggest that species-specific factors determine DNA methylation near CGIs. The transgenic mouse model provides an excellent system to dissect out species-specific regulation of CGI shore methylation. Furthermore, this study lays the foundation for future experiments addressing the role of DNA methylation in regulating human gene expression in the murine context, and examining the validity of transgenic mouse models for the study of human gene regulation.
35

A Novel Approach to Identify Candidate Imprinted Genes in Humans

Shapiro, Jonathan 21 March 2012 (has links)
Many imprinted genes are necessary for normal human development. Approximately 70 imprinted genes have been identified in humans. I developed a novel approach to identify candidate imprinted genes in humans using the premise that imprinted genes are often associated with nearby parent-of-origin-specific DNA differentially methylated regions (DMRs). I identified parent-of-origin-specific DMRs using sodium bisulfite-based DNA (CpG) methylation profiling of uniparental tissues, mature cystic ovarian teratoma (MCT) and androgenetic complete hydatidiform mole (AnCHM), and biparental tissues, blood and placenta. In support of this approach, the CpG methylation profiling led to the identification of parent-of-origin-specific differentially methylated CpG sites (DMCpGs) in known parent-of-origin-specific DMRs. I found new DMRs for known imprinted genes NAP1L5 and ZNF597. Most importantly, I discovered many new DMCpGs, which were associated with nearby genes, i.e., candidate imprinted genes. Allelic expression analyses of one candidate imprinted gene, AXL, suggested polymorphic imprinting of AXL in human blood.
36

A Novel Approach to Identify Candidate Imprinted Genes in Humans

Shapiro, Jonathan 21 March 2012 (has links)
Many imprinted genes are necessary for normal human development. Approximately 70 imprinted genes have been identified in humans. I developed a novel approach to identify candidate imprinted genes in humans using the premise that imprinted genes are often associated with nearby parent-of-origin-specific DNA differentially methylated regions (DMRs). I identified parent-of-origin-specific DMRs using sodium bisulfite-based DNA (CpG) methylation profiling of uniparental tissues, mature cystic ovarian teratoma (MCT) and androgenetic complete hydatidiform mole (AnCHM), and biparental tissues, blood and placenta. In support of this approach, the CpG methylation profiling led to the identification of parent-of-origin-specific differentially methylated CpG sites (DMCpGs) in known parent-of-origin-specific DMRs. I found new DMRs for known imprinted genes NAP1L5 and ZNF597. Most importantly, I discovered many new DMCpGs, which were associated with nearby genes, i.e., candidate imprinted genes. Allelic expression analyses of one candidate imprinted gene, AXL, suggested polymorphic imprinting of AXL in human blood.

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