Global ETD Search

1	Optimization of Cytogenetic and Physical mapping of Culicinae genomes Yang, Fan 02 March 2011 (has links) Understanding chromosome structure and genome organization of Culicine mosquitoes can potentially contribute to the development of novel approaches to vector control. However, because of highly repetitive nature of the Aedes and Culex genomes, the structure of their polytene chromosomes is damaged by ectopic contacts that make the analysis difficult. Mitotic chromosomes from imaginal discs of 4th instar larvae of Aedes aegypti were tested as a source for the physical genome mapping for this mosquito. Chromosomes in imaginal discs are 10 times more abundant than chromosomes in nervous ganglia, and they do not accumulate chromosomal mutation as cell line chromosomes do. Prometaphase chromosomes in imaginal discs of Ae. aegypti are 4-5 times longer than metaphase chromosomes and can provide higher resolution for physical mapping. Cold temperature (+16°C) was proven to increase the number of the chromosomes. Hypotonic solution treatment of live larvae was proven to elongate chromosomes and improve banding patterns. We differentially stained these mitotic chromosomes with Giemsa and YOYO-1 to revile the banding pattern. We applied fluorescent in situ hybridization (FISH) procedure developed for human chromosomes to Ae. aegypti chromosomes. A strain from Culex pipiens, Cx. quinquefasciatus and their hybrids from the natural population in Virginia was successfully colonized in the laboratory. This strain can be used as a reliable source for cytogenetic studies. / Master of Science in Life Sciences Culex pipiens Complex Aedes aegypti Mitotic Chromosome Imaginal Discs Prometaphase Chromosome Genome Mapping
2	Functional Characterization of a Cathepsin L in Drosophila Melanogaster Dong, Qian 01 July 2015 (has links) The Drosophila dorsal Air Sac Primordium (ASP) is a tracheal tube that invasively grows toward and into the wing imaginal disc. The unfolding of Drosophila wing is a process following eclosion with a cuticular bilayer replacing epithelial cells originally packing the wing. We reasoned that protease functions might be needed for the invasion of ASP into the wing imaginal disc as well as the rearrangement of epithelia cells during wing unfolding. Our study is particularly focused on understanding the role of a Cathepsin L like cysteine protease (CP1) in the development of dorsal ASP and wing development of Drosophila melanogaster. To analyze the function of CP1, we overexpressed and knocked down CP1, respectively, using UAS-GAL4 system in combination with RNA interference technology. We found that both the knockdown and overexpression of CP1 in ASP resulted in perturbed growth, migration and weakened invasion of ASPs. We further explored the mechanism by which CP1 regulates ASP development and found that CP1 is capable of degrading collagen IV, a component of extracellular matrix. For wing development, we observed that both the knockdown and overexpression of CP1 in wing imaginal discs interrupted with normal wing development. In summary, our study demonstrated that CP1 facilitates the normal development of ASPs by degrading extracellular matrix and regulates wing development via a complex network of signaling pathways and protein interactions. Knowledge gained from this study has the potential to help us better understand the invasion of tumor cells through the extracellular matrix in humans. Biology Cell and Developmental Biology
3	Death is Not the End: The Role of Reactive Oxygen Species in Driving Apoptosis-induced Proliferation Fogarty, Caitlin E. 02 June 2015 (has links) Apoptosis-induced proliferation (AiP) is a compensatory mechanism to maintain tissue size and morphology following unexpected cell loss during normal development, and may also be a contributing factor to cancer growth and drug resistance. In apoptotic cells, caspase-initiated signaling cascades lead to the downstream production of mitogenic factors and the proliferation of neighboring surviving cells. In epithelial Drosophila tissues, the Caspase-9 homolog Dronc drives AiP via activation of Jun N-terminal kinase (JNK); however, the specific mechanisms of JNK activation remain unknown. Using a model of sustained AiP that produces a hyperplastic phenotype in Drosophila eye and head tissue, I have found that caspase-induced activation of JNK during AiP depends on extracellular reactive oxygen species (ROS) generated by the NADPH oxidase Duox. I found these ROS are produced early in the death-regeneration process by undifferentiated epithelial cells that have initiated the apoptotic cascade. I also found that reduction of these ROS by mis-expression of extracellular catalases was sufficient to reduce the frequency of overgrowth associated with our model of AiP. I further observed that extracellular ROS attract and activate Drosophila macrophages (hemocytes), which may in turn trigger JNK activity in epithelial cells by signaling through the TNF receptor Grindelwald. We propose that signaling back and forth between epithelial cells and hemocytes by extracellular ROS and Grindelwald drives compensatory proliferation within the epithelium, and that in cases of persistent signaling, such as in our sustained model of AiP, hemocytes play a tumor promoting role, driving overgrowth. Apoptosis Apoptosis-induced Proliferation Cancer Caspase Catalase Cell death Chronic Inflammation c-Jun Kinase (JNK) Signaling Dcp-1 DrICE Drosophila Dronc Duox Hemocytes Imaginal Discs Non-apoptotic functions Phoenix Rising Reactive Oxygen Species Regeneration Regulatory Feedback Loop TNF Signaling Tumor Associated Macrophages Wound Healing Cancer Biology Developmental Biology

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