Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--Rutgers University, 2009. / "Graduate Program in Cell and Developmental Biology." Includes bibliographical references (p. 185-197).

Thesis (M.S.)--The University of North Carolina at Greensboro, 2010. / Directed by Amy Adamson; submitted to the Dept. of Biology. Title from PDF t.p. (viewed Jul. 12, 2010). Includes bibliographical references (p. 42-48).

Thesis (M.S.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains vi, 90 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 79-90).

Thesis (Ph. D.)--University of Chicago, Committee on Cancer Biology, December 2002. / Includes bibliographical references. Also available on the Internet.

Thèse (M.Sc.) -- Université Laval, 1998. / Bibliogr.: f. [66]-80. Publié aussi en version électronique.

Centro Universitário de Patos de Minas / Caryocar brasiliense is a plant popularly known as pequi, native from the Brazilian cerrado , and is widely used in Brazilian cookery. Its fruit presents a high level - carotenes (which is a pro-vitamin A), retinol and vitamin C. These are efficient antioxidizing components, and they scavenging free radicals and prevent mutagenic action of physical and chemical agents. However, in high concentrations it may have mutagenic and recombinogenic effects. So to valuate the genotoxic effects of the pequi we prepared aqueous extracts of pequi (AEP) in concentrations of 1%, 5% and 10%. For this we used the wing spot test in Drosophila melanogaster (Somatic Mutation And Recombination Test SMART). The SMART was fulfilled through the following crossings: 1) standard cross (ST); flare3 virgin females (flr3/TM3, Bds) were crossed with mwh/mwh males; 2) HB High Bioactivation Cross which ORR (ORR, flr3/TM3, Bds) virgin females were crossed with mwh/mwh males. From these crossings, we obtained two kinds of descendents: marked heterozygote (MH - mwh +/+ flr3); balanced heterozygote (BH - mwh +/+TM3, Bds). 72-hour larvae from both crossings were treated with different concentrations of AEP (1%, 5% e 10%). Distilled water and doxorubicin (DXR) (0,125mg/mL) were respectively used as negative and positive controls. The present study aimed the valuating the genotoxic effects of AEP and its antigenotoxic effects against the genotoxic action of DXR (0,125mg/mL). The results obtained demonstrated that AEP induced a statistically significant increase in the frequency of mutant spots, when compared to negative control in all concentrations of HB crossi and only in the concentration of 10 % of ST crossi. In the analysis of HB descendents, we observed a recombinogenic effect of AEP, only when metabolized by P-450. When associated to DXR, there may be an overpotentiality of the genotoxic effect of this chemotherapy. This way, we may conclude that, in these experimental conditions and in the tested concentrations, the aqueous extract of pequi presented a mutagenic and recombinogenic potential. / A Caryocar brasiliense é uma planta, conhecida popularmente como pequi, nativa do cerrado brasileiro, amplamente utilizada na culinária brasileira. O fruto do pequizeiro apresenta alto teor de carotenos (que é uma pro-vitamina A) e retinol e vitamina C. Esses compostos são eficientes antioxidantes, seqüestrando radicais livres e prevenindo a ação mutagênica de agentes físicos e químicos. Contudo, em altas concentrações, podem ter efeitos recombinogênicos e mutagênicos. Para avaliar os efeitos genotóxicos do pequi foram preparados extratos aquosos do pequi (EAP) nas concentrações de 1%; 5% e 10%. Para tanto, utilizou-se o teste da mancha da asa em Drosophila melanogaster (Somatic Mutation And Recombination Test SMART). O SMART foi realizado por meio dos seguintes cruzamentos: 1) cruzamento Padrão (ST Standard Cross): fêmeas virgens flare3 (flr3/TM3, Bds) foram cruzadas com machos mwh/mwh; 2) cruzamento de alta bioativação (HB High Bioactivation Cross ), no qual fêmeas virgens ORR (ORR, flr3/TM3, Bds) foram cruzadas com machos mwh/mwh. Desses cruzamento foram obtidos dois tipos de descendentes: heterozigoto marcado (MH - mwh +/+ flr3); heterozigoto balanceado (BH - mwh +/+ TM3, Bds). Larvas de 72 horas, de ambos cruzamentos, foram tratadas com diferentes concentrações de EAP (1%, 5% e 10%). Como controles negativo e positivo foram utilizados, respectivamente, água destilada e doxorrubicina (DXR) (0,125mg/mL). O trabalho teve como objetivo avaliar os efeitos genotóxicos do EAP e seus efeitos antigenotóxicos contra a ação genotóxica da DXR (0,125mg/mL). Os resultados obtidos demonstraram que o EAP induziu um aumento, estatisticamente significativo, na freqüência de manchas mutantes quando comparado com o controle negativo em todas as concentrações do cruzamento HB e somente na concentração de 10% do cruzamento ST. Na análise dos descentes BH observou-se efeito recombinogênico, do EAP, somente quanto metabolizado pelas P-450. Quando associado a DXR ocorre uma potencialização do efeito genotóxico desse quimioterápico. Portanto, pode-se concluir que, nestas condições experimentais e nas concentrações testadas, o extrato aquoso de pequi apresentou um potencial mutagênico e recombinogênico. / Mestre em Genética e Bioquímica

Transposable elements (TEs) are mutagenic mobile DNA sequences whose excision and insertion are powerful drivers of evolution. Some TE families are known to target specific genome features, and studying their insertion preferences can provide information about both TE biology and the state of the genome at these locations. To investigate this, collecting large numbers of insertion sites for TEs in natural populations is required. Genome resequencing data can potentially provide a rich source of such insertion sites. The field of detecting these "non-reference" TE insertions is an active area of research, with many methods being released and no comprehensive review performed. To drive forward knowledge of TE biology and the field of non-reference TE detection, we created McClintock, an integrated pipeline of six TE detection methods. McClintock lowers the barriers against use of these methods by automating the creation of the diverse range of input files required whilst also setting up all methods to run simultaneously and standardising the output. To test McClintock and its component methods, it was run on both simulated and real Saccharomyces cerevisiae data. Tests on simulated data reveal the general properties of component methods' predictions as well as the limitations of simulated data for testing software systems. Overlap between results from the McClintock component methods show many insertions detected by only one method, highlighting the need to run multiple TE detection methods to fully understand a resequenced sample. Utilising the well characterised properties of S. cerevisiae TE insertion preferences, real yeast population resequencing data can act as a biological validation for the predictions of McClintock. All component methods recreated previously known biological properties of S. cerevisiae TE insertions in natural population data. To demonstrate the versatility of McClintock, we applied the system to Drosophila melanogaster resequencing data. 27 Schneider's cell lines were sequenced and analysed with McClintock. In addition to demonstrating the scalability of McClintock to larger genomes with more TE families, this exposed ongoing transposition in S2 cell lines. Likewise, the use of non-reference TE insertions as variable sites allowed us to recreate the relationships between S2 sub-lines, confirming that S1, S2, and S3 were most likely established separately. The results also suggest that there are several S2 sub-lines in use and that these sub-lines can differ from each other in TE content by hundreds of non-reference TE copies. Overall this thesis demonstrates that the McClintock pipeline can highlight problems in TE detection from genome data as well as revealing that much can still be learned from this data source.

Adipokinetic hormones (AKHs) are neuropeptides from the arthropod AKH/RPCH (adipokinetic hormone/ red pigment concentrating hormone) family. The typical AKH is an octa-, nona- or decamer that is synthesized, stored and released by the neurosecretory cells of the corpora cardiaca (CC) connected to the brain and primarily involved in the mobilization of energy reserves from the fat body in insects. In addition to its well established role in energy metabolism, AKH has also been implicated to be involved in stress responses specifically to oxidative stress. Oxidative stress induced elevation of AKH levels as well as a modulation of biomarkers of oxidative damage following exogenous application of AKH have been demonstrated. However, the discrete steps involved in the mode of action of AKH in triggering an anti-oxidative response is far from clear. Given the role of AKH as a neuroendocrine factor that mediates a response to oxidative stress, the mode of action of AKH at the sub-cellular level was investigated. Using isolated central nervous system (brain) as an in vitro model, we establish that AKH can potentiate an anti-oxidative response to oxidative stress. Further, we also demonstrate that AKH uses a conserved signal transduction mechanism involving both protein kinase C (PKC) and cyclic adenosine monophosphate (cAMP) and by mobilizing both intra as well as extra-cellular Ca2+ stores to elaborate its anti-oxidative response. Finally, using the genetically tractable fruit fly Drosophila melanogaster, we demonstrate through RNAi mediated knockdown of AKH synthesis as well as overexpression of AKH using the GAL4/UAS system, that the fork-head box transcription factor (dFoXO) might function downstream of AKH signaling in its stress responsive role. These results implicate AKH as a stress hormone while offering possibilities to further identify specific regulatory mechanisms and downstream effector molecules. Since stress signaling pathways are conserved, insights obtained from such studies on insects will offer some unique avenues for understanding stress responses and related pathologies in vertebrates including humans.

Oxidative stress is caused by an imbalance between high production of reactive oxygen species and ability of organism to detoxify them or counteract their effects. The chromosomal ends telomeres - are specialized nucleoprotein structures protecting chromosome ends from DNA damage. Telomeres of Drosophila melanogaster are arrays of specific non-long terminal repeated (LTR) retrotransposons HeT-A, TART and TAHRE. This thesis evaluates effects of exposure of paraquat, which is a strong oxidative stress inducer, on telomere length and transcription activity in Drosophila.