• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 3
  • Tagged with
  • 27
  • 27
  • 27
  • 15
  • 8
  • 6
  • 6
  • 6
  • 6
  • 6
  • 5
  • 4
  • 4
  • 4
  • 4
  • 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.
11

Translational insights into the genetic etiology of mental health disorders: Examining risk factor models, neuroimaging, and current dissemination practices

Bourdon, Jessica L 01 January 2019 (has links)
Psychiatric genetics is a basic science field that has potential for practical application and effective translation. To date, translational frameworks utilized by this field have been linear (e.g., sequential) in nature, focusing on molecular genetic information. It is proposed that non-linear (e.g., socio-ecological) frameworks are a better way to immediately translate non-molecular genetic information. This dissertation explored the translation of psychiatric genetic information in two ways. First, a survey was sent to academic stakeholders to assess the state of the science regarding the translation of genetic information to the clinical care of mental health disorders. Findings from this indicate a translation-genetic competence gap whereby genetic knowledge reinforces linear frameworks and genetic competence is needed to achieve effective translation in this content area. Second, a new risk factor model for social anxiety was created that incorporated genetic, environmental, and neurophysiological risk factors (behavioral inhibition, parental bonding, emotion reactivity). Findings indicate that genetic etiology is more informative knowledge that can influence risk factor models and possibly prevention and intervention efforts for social anxiety. Overall this dissertation paves the way for examining the translational capacity of psychiatric genetics in a clinical setting. It constitutes the first examination of barriers to and a potential solution for the most effective translation of psychiatric genetic information.
12

THE ROLE OF ANGIOTENSINOGEN IN ATHEROSCLEROSIS AND OBESITY

Wu, Congqing 01 January 2014 (has links)
Angiotensinogen is the only known precursor in the renin-angiotensin system, a hormonal system best known as an essential regulator of blood pressure and fluid homeostasis. Angiotensinogen is sequentially cleaved by renin and angiotensin- converting enzyme to generate angiotensin II. As the major effector peptide, angiotensin II mainly function through angiotensin type 1 receptor. Angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and more recently renin inhibitors are widely known as the 3 classic renin-angiotensin system inhibitory drugs against hypertension and atherosclerosis. Here, we developed an array of regents to explore the effects of angiotensinogen inhibition. First, we demonstrated that genetic deficiency of angiotensinogen not only protected against hypercholesterolemia- induced atherosclerosis but also prevented diet-induced obesity. Then we found weekly intraperitoneal injection of antisense oligonucleotides against angiotensinogen remarkably surpressed body weight gain in mice fed a western diet, which was absent from classic renin-angiotensin system inhibition. The suppressed body weight gain was attributable to diminished body fat mass gain and enhanced energy expenditure. More excitingly, angiotensinogen antisense oligonucleotides regressed body weight gain on obese mice. Together, our findings revealed a unique feature of angiotensinogen inhibition beyond classic renin angiotensin inhibition and demonstrated therapeutic potentials of angiotensinogen antisense oligonucleotides against hypertension, atherosclerosis, and obesity. We also developed an in vivo system to explore the functional consequences of disrupting a conserved Cys18-Cys137 disulfide bridge in angiotensinogen. The formation of this disulfide bridge could trigger conformational changes in angiotensinogen, thereby facilitating renin cleavage of angiotensinogen. It was predicted that the redox-sensitive disulfide bridge might change the efficiency of angiotensinogen/renin reaction to release angiotensin II, thus modulate angiotensin II-dependent functions. We determined effects of the presence and absence of the disulfide bridge on angiotensin II concentrations and responses in mice expressing either native angiotensinogen or Cys18Ser, Cys137Ser mutated angiotensinogen in liver via adeno-associated viral vectors. Contrary to the prediction, disruption of Cys18-Cys137 disulfide bridge in angiotensinogen had no discernible effects on angiotensin II production and angiotensin II-dependent functions in mice.
13

Turn Me On or Off: A Study On Epigenetics and Merleau-Ponty in Angela Carter’s “The Lady of the House of Love”

Skarlinsky, Solsiree Lynn 30 March 2016 (has links)
This study aims to trace points of intersection between the too often divorced disciplines of literature, continental philosophy, and the hard sciences in Angela Carter’s “The Lady of the House of Love.” In short, this thesis will not only explore how such conversations surface within the short story, but will also serve as an explication of Maurice Merleau-Ponty’s philosophy of body and space, and the theory of epigenetics. Through these explications, the thesis itself will also gear one discipline towards the other as both theories intimately bind the environment with the body, and the body with the environment. Thus, the body and the environment are not separate and passive, but active and intertwined in a manner much like the aforementioned disciplines I posit are. Therefore, the goal of this thesis is to first postulate that such conversations between literature, philosophy, and science are already occurring, and as such, stress that such conversations need further discussion and exploration.
14

Dosage Compensation of Trisomy 21 and Its Implications for Hematopoietic Pathogenesis in Down Syndrome

Chiang, Jen-Chieh 06 November 2017 (has links)
Down Syndrome (DS), the most common aneuploidy seen in live-borns, is caused by trisomy for chromosome 21. DS imposes high risks for multiple health issues involving various systems of the body. The genetic complexity of trisomy 21 and natural variation between all individuals has impeded understanding of the specific cell pathologies and pathways involved. In addition, chromosomal disorders have been considered outside the hopeful progress in gene therapies for single-gene disorders. Here we test the feasibility of correcting imbalanced expression of genes across an extra chromosome by expression of a single gene, XIST, the key player in X chromosome inactivation. We targeted a large XIST transgene into one chromosome 21 in DS iPS cells, and demonstrated XIST RNA spreads and induces heterochromatin and gene silencing across that autosome in cis. By making XIST inducible, this allows direct comparison of effects of trisomy 21 expression on cell function and phenotypes. Importantly, XIST-induction during in vitro hematopoiesis normalized excess production of differentiated blood cell types (megakaryocytes and erythrocytes), known to confer high risk for myeloproliferative disorder and leukemia. In contrast, trisomy silencing enhances production of iPS and neural stem cells, consistent with DS clinical features. Further analysis revealed that trisomy 21 initially impacts the endothelial hematopoietic transition (EHT) to generate excess CD43+ progenitors, and also increases their colony forming potential. Furthermore, results provide evidence for a key role for enhanced IGF signaling, involving over-expression of non-chromosome 21 genes controlled by trisomy 21. Finally, experiments to examine trisomy effects on angiogenesis showed no effect on production of endothelial cells, but it remains unclear whether trisomic cells may differ in ability to form vessels. Collectively, this thesis demonstrates proof-of-principle for XIST-mediated “trisomy silencing”. Phenotypic improvement of hematopoietic and neural stem cells demonstrates the value for research into DS pathogenesis, but also provides a foundation of potential for future development of “chromosome therapy” for DS patients.
15

Effects of Reactive Oxygen Species on Life History Traits of Caenorhabditis elegans

Smith, Samson William 01 January 2012 (has links)
Evolutionary life history theory predicts that tradeoffs among fitness-related phenotypes will occur as a result of resource limitations and/or physiological constraints. Such tradeoffs are defined as the cost(s) incurred on one component of fitness (e.g., reproduction) by the increased expression of another fitness-related trait (e.g., longevity). Only recently have researchers begun to investigate the mechanistic bases of life history tradeoffs. A recent proposal is that reactive oxygen species (ROS) have a central role in shaping life history traits and tradeoffs. Research on disparate animal taxa has highlighted strong correlations between oxidative stress resistance and fitness-related life history traits, for example. Here, I use the model organism Caenorhabditis elegans to test several hypotheses concerning the effects of ROS on life history traits and the manifestation of life history tradeoffs. Additionally, I use heat stress and an alternate food source to explore the responses of life history traits to other forms of physiological stress. Relative fitness and other traits related to reproduction were found to be affected in mostly negative ways by increasing oxidative insult. Lifespan was surprisingly unaffected by oxidative stress, but was modified by temperature. In vivo ROS levels as measured by fluorescent microscopy reveal a tradeoff between antioxidant production and reproduction in this species.
16

OVEREXPRESSION/SILENCING OF SELECTED SOYBEAN GENES ALTERS RESISTANCE TO PATHOGENS

El-Habbak, Mohamed H. 01 January 2013 (has links)
Plant diseases remain a major obstruction to meeting the world’s increased demand for soybean oil and protein. Reducing the losses caused by diseases in order to improve crop production is a high priority for agricultural research. The need for novel strategies for plant disease control cannot be overstated. In the present study, selected defense-related genes were silenced and/or overexpressed in soybean using a virus-based vector and the resultant plants were tested for their responses to pathogens. The first part of the study focused on Rps1k (Resistance to Phytophthora sojae) gene. The two conserved domains encoding ‘P-Loop NTPase’ and ‘PLN03210’ of Rps1k were independently overexpressed. Stem inoculation assays for the overexpressing plants showed significant resistance to virulent races; 90% standing plants compared to 10% in controls. Lesion length was greatly restricted only in case of plants overexpressing ‘PLN03210’. Simultaneous silencing of Rps1k-1 and Rps1k-2 resulted in remarkable susceptibility to avirulent races when tested by a detached-leaf assay. The second part of the study entailed silencing/overexpression of the chlorophyllase genes GmCLH1 and GmCLH2 and testing the responses of the silenced/overexpressing plants to the sudden death pathogen Fusarium virguliforme. Four weeks post root inoculation, GmCLH2-silenced plants showed enhanced resistance while the GmCLH2-overexpressing plants exhibited markedly increased susceptibility when compared to empty vector control. RT-PCR assay of PR genes revealed elevated expression of PR2 and PR4 in GmCLH2-silenced plants. In the third part of the study, soybean plants silenced for a leucine-rich repeat receptor-like kinase (GmRLK3) gene were examined for their responses to different pathogens. Silencing of GmRLK3 enhanced susceptibility to infection with Alternaria tenuissima or Sclerotinia sclerotiorum as revealed by rapid disease progress on treated leaves. Surprisingly, silencing of GmRLK3 in known susceptible soybean cultivars rendered the silenced plants resistant to P. sojae. The ensuing partial resistance to P. sojae was consistent with results of RT-PCR assays that showed a significant increase in the transcript level of the osmotin-encoding gene (PR5a) in the GmRLK3-silenced plants. PR5a is considered a marker for systemic acquired resistance.
17

Functional Characterization of rai1 in Zebrafish

Beach, Joshua S 01 January 2015 (has links)
Smith-Magenis Syndrome (SMS; OMIM #182290) is a multiple congenital abnormality and intellectual disability (ID) disorder caused by either an interstitial deletion of the 17p11.2 region containing the retinoic acid induced-1 (RAI1) gene or a mutation of the RAI1 gene. Individuals diagnosed with SMS typically present characteristics such as ID, self-injurious behavior, sleep disturbance, ocular and otolaryngological abnormalities, craniofacial and skeletal abnormalities, neurological and behavioral abnormalities, as well as other systemic defects and manifestations. Previous work by Vyas in 2009 showed temporal expression of rai1 in zebrafish embryos as early as 9 hpf. We hypothesize that there is maternal rai1 expression as early as zero hours post fertilization in wild type embryos. Using end-point PCR, we found that in fact there is maternal rai1 expression is detectable as early as 2 hours post fertilization (hpf) in wild type zebrafish embryos. Furthermore, we quantified rai1 expression using qPCR and found that rai1 expression declines significantly after 6 hpf. We hypothesize that a down regulation of rai1 or loss of rai1 will lead to morphological phenotypes, especially if that loss of rai1 function occurs during the earliest stages of zebrafish embryogenesis. Using a rai1morpholino oligonucleotide (MO), we found a loss of rai1 expression did not induce a morphological phenotype in in wild type embryos; furthermore, we also found that a loss of maternal rai1 expression did not induce a morphological phenotype as well. Utilizing a mutant rai1 zebrafish line, we found that both rai1 +/fh370 progeny nor rai1 fh370/fh370 progeny exhibited a morphological phenotype and that downstream targets such as bdnf were not affected by a reduction or complete loss of rai1. Prior research has shown that retinoic acid (RA) can induce rai1 expression. We hypothesize that RA can induce expression of rai1 during zebrafish embryogenesis. Using wild type fish and a rai1 in situ hybridization probe, we found that RA treatment at 25 hpf induced expression of rai1. The construction of a rai1 overexpression vector used for overexpression studies was started. Further development of GFP expression vector and zebrafish rai1 antibody are needed to determine if the morpholino is reducing rai1 protein expression.
18

Acclimatization of the Tropical Reef Coral Acropora millepora to Hyperthermal Stress

Bellantuono, Anthony John 05 September 2013 (has links)
The demise of reef-building corals potentially lies on the horizon, given ongoing climate change amid other anthropogenic environmental stressors. If corals cannot acclimatize or adapt to changing conditions, dramatic declines in the extent and health of the living reefs are expected within the next half century. The primary and proximal global threat to corals is climate change. Reef-building corals are dependent upon a nutritional symbiosis with photosynthetic dinoflagellates belonging to the group Symbiodinium. The symbiosis between the cnidarian host and algal partner is a stress-sensitive relationship; temperatures just 1°C above normal thermal maxima can result in the breakdown of the symbiosis, resulting in coral bleaching (the loss of Symbiodinium and/or associated photopigments) and ultimately, colony death. As ocean temperatures continue to rise, corals will either acclimatize or adapt to changing conditions, or will perish. By experimentally preconditioning the coral Acropora millepora via sublethal heat treatment, the coral acquired thermal tolerance, resisting bleaching during subsequent hyperthermal stress. The complex nature of the coral holobiont translates to multiple possible explanations for acclimatization: acquired thermal tolerance could potentially originate from the host itself, the Symbiodinium, or from the bacterial community associated with the coral. By examining the type of in hospite Symbiodinium and the bacterial community prior acclimation and after thermal challenge, it is shown that short-term acclimatization is not due to a distinct change in the dinoflagellate or prokaryote community. Though the microbial partnerships remain without considerable flux in preconditioned corals, the host transcriptome is dynamic. One dominant pattern was the apparent tuning of gene expression observed between preconditioned and non-preconditioned treatments, showing a modulated transcriptomic response to stress. Additionally several genes were upregulated in association with thermal tolerance, including antiapoptotic genes, lectins, and oxidative stress response genes. Upstream of two of these thermal tolerance genes, inhibitor of NFκB and mannose-binding lectin, DNA polymorphisms were identified which vary significantly between the northern and southern Great Barrier Reef. The impact of these mutations in putative promoter regions remains to be seen, but variation across thermally-disparate geography serves to generate hypotheses regarding the role of regulatory element evolution in a coral adaptation context.
19

Patterns of Morphological Plasticity in Metriaclima zebra and Danio rerio Suggest Differently Canalized Phenotypes Due to Form-Function Relationships

Jockel, Dylan 29 October 2019 (has links)
In order to ascertain the degree of compatibility in developmental restructuring and behavioral plasticity between two fish species frequently made subject of laboratory research (Metriaclima zebra & Danio rerio), alternative trophic niche exposure experiments utilizing novel three-prong feeding treatments were conducted to obtain morphometric data, which demonstrated both species do bear some degree of plasticity. The results are somewhat complicated by differences in locality of detectable restructuring, which may be due to disparity in the form-function relationship for each species’ lineage. Each is notable in the manner of respective species’ jaw protrusion, as it is driven by anterior kinethmoid rotation in D. rerio. as opposed to force imparted upon the rostral cartilage of the premaxilla’s articular process in M zebra. Each is markedly distinct in the pharyngeal jaw as well, as zebrafish (also toothless at the oral jaw) bear teeth only on the lower set at the posterior of the mouth, while cichlids bear teeth on all jaws and additionally possess a unique, fused lower pharyngeal jaw. However, accounting for this difference in experimental models does allow for direct comparison, both at the morphological/behavioral and potentially the genetic level, though additional research is necessary. The evidence provided here also provides encouragement that more nuanced approaches to laboratory trophic niche exposure experiments could elucidate further evidence on the nature of phenotypic plasticity.
20

Genomic and Transcriptomic Investigation of Endemic Burkitt Lymphoma and Epstein Barr Virus

Kaymaz, Yasin 31 July 2017 (has links)
Endemic Burkitt lymphoma (eBL) is the most common pediatric cancer in malaria-endemic equatorial Africa and nearly always contains Epstein-Barr virus (EBV), unlike sporadic Burkitt Lymphoma (sBL) that occurs with a lower incidence in developed countries. Despite this increased burden the study of eBL has lagged. Additionally, while EBV was isolated from an African Burkitt lymphoma tumor 50 years ago, however, the impact of viral variation in oncogenesis is just beginning to be fully explored. In my thesis research, I focused on investigating molecular genetics of the endemic form of this lymphoma with a particular emphasis on the role of the virus and its variation in pathogenesis using novel sequencing and bioinformatic strategies. First, we sought to understand pathogenesis by investigating transcriptomes using RNA sequencing (RNAseq) from 30 primary eBL tumors and compared to sBL tumors. BL tumor samples were prospectively obtained from 2009 until 2012 in Kenya. Within eBL tumors, minimal expression differences were found based on anatomical presentation site, in-hospital survival rates, and EBV genome type; suggesting that eBL tumors are homogeneous without marked subtypes. The outstanding difference detected using surrogate variable analysis was the significantly decreased expression of key genes in the immunoproteasome complex in eBL tumors carrying type 2 EBV compared to type 1 EBV. Secondly, in comparison to previously published pediatric sBL specimens, the majority of the expression and pathway differences were related to the PTEN/PI3K/mTOR signaling pathway and was correlated most strongly with EBV status rather than the geographic designation. Moreover, the common mutations were observed significantly less frequently in eBL tumors harboring EBV type 1, with mutation frequencies similar between tumors with EBV type 2 and without EBV. In addition to the previously reported genes, we identified a set of new genes mutated in BL. Overall, these suggested that EBV, particularly EBV type 1, supports BL oncogenesis alleviating the need for particular driver mutations in the human genome. Second, we sought to comprehensively define sequence variations of EBV across the viral genome in eBL tumor cells and normal infections, and correlate variations with clinical phenotypes and disease risk. We investigated the whole genome sequence of EBV from primary tumors (N=41) and plasma from eBL patients (N=21) as well as EBV in the blood of healthy children (N=29) within the same malaria endemic region. We conducted a genome wide association analysis study with viral genomes of healthy kids and BL kids. Furthermore, we found that the frequencies of EBV types among healthy kids were at equal levels while they were skewed in favor of type 1 (70%) among eBL kids. To pinpoint the fundamental divergence between viral genome subtypes, type 1 and type 2, we constructed phylogenetic trees comparing to all public EBV genomes. The pattern of variation defined the substructures correlated with the subtypes. This investigation not only deciphers the puzzling pathogenic differences between subtypes but also helps to understand how these two EBV types persist in the population at the same time. Overall, this research provides insight into the molecular underpinning of eBL and the role of EBV. It further provides the groundwork and means to unravel the complexity of EBV population structure and provide insight into the viral variation that may influence oncogenesis and outcomes in eBL and other EBV-associated diseases. In addition, genomic and mutational analyses of Burkitt lymphoma tumors identify key differences based on viral content and clinical outcomes suggesting new avenues for the development of prognostic molecular biomarkers and therapeutic interventions.

Page generated in 0.0635 seconds