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Full-Text Articles in Molecular Biology

Epigenetic Mechanisms Governing Behavioral Reprogramming In The Ant Camponotus Floridanus, Riley John Graham Jan 2018

Epigenetic Mechanisms Governing Behavioral Reprogramming In The Ant Camponotus Floridanus, Riley John Graham

Publicly Accessible Penn Dissertations

Eusocial insect colonies divide behaviors among specialist groups called castes. In some species, caste identity is determined by the interaction of endogenous (e.g. genomic) and exogenous (e.g. juvenile hormone from nurses) signals during larval development, suggesting epigenetic mechanisms underlie plastic traits tied to caste identity. Previous work demonstrated a link between patterns of histone H3 lysine 27 acetylation (H3K27ac) and caste-specific gene expression in Major and Minor workers of the ant Camponotus floridanus, and we hypothesized caste-specific behaviors such as foraging may be similarly regulated by histone acetylation. To test this hypothesis, we fed mature (~30d old) Majors ...


The Human Heterochromatin Landscape: Genomic Subtypes, Bound Proteins, And Contributions To Cell Identity, Justin S. Becker Jan 2017

The Human Heterochromatin Landscape: Genomic Subtypes, Bound Proteins, And Contributions To Cell Identity, Justin S. Becker

Publicly Accessible Penn Dissertations

Large portions of mammalian genomes are packaged into structurally compact heterochromatin, which protects genome integrity and suppresses transcription of lineage-inappropriate genes. Characterization of heterochromatic regions has relied on genomic mapping of associated histone modifications, such as H3K9me3 and H3K27me3, and purification of proteins interacting with these modifications. Heterochromatic regions marked by H3K9me3 have been shown to impede gene activation during reprogramming to pluripotency, and I find that H3K9me3 domains can similarly impede conversion of fibroblasts to hepatocytes. However, both H3K9me3 and H3K27me3 can be found in transcriptionally active chromatin, limiting the accuracy of histone marks alone for identifying heterochromatin domains ...


Genomic Imprinting: Establishment, Maintenance And Stability Of Dna Methylation Imprints, Lara Kimberly Abramowitz Jan 2013

Genomic Imprinting: Establishment, Maintenance And Stability Of Dna Methylation Imprints, Lara Kimberly Abramowitz

Publicly Accessible Penn Dissertations

Genomic imprinting is an epigenetic phenomenon in which genes are monoallelicaly expressed according to their parent-of-origin. Imprinted expression entails marking parental chromosomes so that a specific parental allele is stably repressed or expressed. Differential DNA methylation is essential for marking and regulating imprinted genes and is often found at imprinting control regions (ICRs). These DNA methylation imprints must be maintained throughout early development despite genome-wide epigenetic reprogramming to allow for stable allelic expression in differentiated tissues. Moreover, marking of the alleles must be erased in the germline so that establishment of sex-specific marks can occur during gametogenesis. These processes are ...


Cellular Mechanisms Of Mammalian Liver Regeneration, Kilangsungla Yanger Jan 2013

Cellular Mechanisms Of Mammalian Liver Regeneration, Kilangsungla Yanger

Publicly Accessible Penn Dissertations

ABSTRACT

CELLULAR MECHANISMS OF MAMMALIAN LIVER REGENERATION

Kilangsungla Yanger

Ben Z. Stanger

The liver is an essential organ that aids in metabolic processes, protein synthesis and detoxification of harmful substances. As the centre for detoxification, the liver is able to compensate for this routine damage with its robust regenerative ability. All vertebrate livers, for example, can make up for tissue mass loss (via surgical excision of a portion of the liver) by replication of their differentiated cells within the remnant lobes. These differentiated cells include parenchymal cells such as the hepatocytes and biliary epithelial cells (BECs) and also non-parenchymal cells ...