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Description
Many factors are at play within the genome of an organism, contributing to much of the diversity and variation across the tree of life. While the genome is generally encoded by four nucleotides, A, C, T, and G, this code can be expanded. One particular mechanism that we examine in this thesis is modification of bases—more specifically, methylation of Adenine (m6A) within the GATC motif of Escherichia coli. These methylated adenines are especially important in a process called methyl-directed mismatch repair (MMR), a pathway responsible for repairing errors in the DNA sequence produced by replication. In this pathway, methylated adenines identify the parent strand and direct the repair proteins to correct the erroneous base in the daughter strand. While the primary role of methylated adenines at GATC sites is to direct the MMR pathway, this methylation has also been found to affect other processes, such as gene expression, the activity of transposable elements, and the timing of DNA replication. However, in the absence of MMR, the ability of these other processes to maintain adenine methylation and its targets is unknown.
To determine if the disruption of the MMR pathway results in the reduced conservation of methylated adenines as well as an increased tolerance for mutations that result in the loss or gain of new GATC sites, we surveyed individual clones isolated from experimentally evolving wild-type and MMR-deficient (mutL- ;conferring an 150x increase in mutation rate) populations of E. coli with whole-genome sequencing. Initial analysis revealed a lack of mutations affecting methylation sites (GATC tetranucleotides) in wild-type clones. However, the inherent low mutation rates conferred by the wild-type background render this result inconclusive, due to a lack of statistical power, and reveal a need for a more direct measure of changes in methylation status. Thus as a first step to comparative methylomics, we benchmarked four different methylation-calling pipelines on three biological replicates of the wildtype progenitor strain for our evolved populations.
While it is understood that these methylated sites play a role in the MMR pathway, it is not fully understood the full extent of their effect on the genome. Thus the goal of this thesis was to better understand the forces which maintain the genome, specifically concerning m6A within the GATC motif.
To determine if the disruption of the MMR pathway results in the reduced conservation of methylated adenines as well as an increased tolerance for mutations that result in the loss or gain of new GATC sites, we surveyed individual clones isolated from experimentally evolving wild-type and MMR-deficient (mutL- ;conferring an 150x increase in mutation rate) populations of E. coli with whole-genome sequencing. Initial analysis revealed a lack of mutations affecting methylation sites (GATC tetranucleotides) in wild-type clones. However, the inherent low mutation rates conferred by the wild-type background render this result inconclusive, due to a lack of statistical power, and reveal a need for a more direct measure of changes in methylation status. Thus as a first step to comparative methylomics, we benchmarked four different methylation-calling pipelines on three biological replicates of the wildtype progenitor strain for our evolved populations.
While it is understood that these methylated sites play a role in the MMR pathway, it is not fully understood the full extent of their effect on the genome. Thus the goal of this thesis was to better understand the forces which maintain the genome, specifically concerning m6A within the GATC motif.
ContributorsBoyer, Gwyneth (Author) / Lynch, Michael (Thesis director) / Behringer, Megan (Committee member) / Geiler-Samerotte, Kerry (Committee member) / School of Life Sciences (Contributor) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
The current study investigated whether intermittent restraint stress (IRS) would impair fear extinction learning and lead to increased anxiety and depressive- like behaviors and then be attenuated when IRS ends and a post- stress rest period ensues for 6 weeks. Young adult, male Sprague Dawley rats underwent restraint stress using wire mesh (6hr/daily) for five days with two days off before restraint resumed for three weeks for a total of 23 restraint days. The groups consisted of control (CON) with no restraint other than food and water restriction yoked to the restrained groups, stress immediate (STR-IMM), which were restrained then fear conditioned soon after the end of the IRS paradigm, and stress given a rest for 6 weeks before fear conditioning commenced (STR-R6). Rats were fear conditioned by pairing a 20 second tone with a footshock, then given extinction training for two days (15 tone only on each day). On the first day of extinction, all groups discriminated well on the first trial, but then as trials progressed, STR-R6 discriminated between tone and context less than did CON. On the second day of extinction, STR- IMM froze more to context in the earlier trials than compared to STR-R6 and CON. As trials progressed STR-IMM and STR-R6 froze more to context than compared to CON. Together, CON discriminated between tone and context better than did STR-IMM and STR-R6. Sucrose preference, novelty suppressed feeding, and elevated plus maze was performed after fear extinction was completed. No statistical differences were observed among groups for sucrose preference or novelty suppressed feeding. For the elevated plus maze, STR-IMM entered the open arms and the sum of both open and closed arms fewer than did STR- R6 and CON. We interpret the findings to suggest that the stress groups displayed increased hypervigilance and anxiety with STR-R6 exhibiting a unique phenotype than that of STR-IMM and CON.
ContributorsShah, Vrishti Bimal (Author) / Conrad, Cheryl (Thesis director) / Newbern, Jason (Committee member) / Judd, Jessica (Committee member) / School of Life Sciences (Contributor) / Sanford School of Social and Family Dynamics (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Limited research has analyzed how culture might influence the utilization of social support. To address this deficiency, the present study investigated preferences for social support among East-Asian, Hispanic, and White participants. In this set of studies, a comprehensive social support taxonomy was constructed in order to better identify and conceptualize the various support subtypes found in the literature. Based on the taxonomy, a questionnaire measure for preferences of different types of social support was developed. Participants were asked to rate how helpful they would find each supportive action made by a friend or family member on a seven-point Likert scale. Based on the responses of 516 Amazon Mechanical Turk workers, a five-factor solution for an 18-item scale emerged from a factor analysis. The social support subscales supported by the factor analysis were emotional, tangible, self-referencing, reappraisal, and distraction. The questionnaire was used to assess similarities and differences among East-Asian, Hispanic, and White participants in terms of preferences for providing and receiving social support. Based on the results of 299 college-age students, an analysis of variance on individually standardized ("ipsatized") responses was conducted in order to eliminate the positioning effect of culture. A main effect of ethnicity (p=.05) and an interaction between ethnicity and sex (p=.02) were significant for the preference of tangible social support. A main effect of ethnicity (p=.04) and an interaction between ethnicity and sex (p=.05) were significant for the preference of reappraisal social support. Clinical implications of our research findings are discussed.
ContributorsCampagna, Allegra Xiu Hong (Author) / Shiota, Michelle N. (Thesis director) / Campos, Belinda (Committee member) / Yee, Claire (Committee member) / School of Life Sciences (Contributor) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Students Organize for Syria (SOS) is the student led initiative for Syria. With 18 registered chapters across the United States, this student organization is targeting a multidimensional cause by different means. Though it is now a national movement, it started off with one group at Arizona State University, with one student. Zana Alattar, founder and student director of SOS, tells the story of how she took an ASU organization, Save Our Syrian Freedom (SOS Freedom), to the national level as SOS. As a pre-medical student, she also combines her work in human rights with her future in healthcare. After all, health and human rights have long maintained a synergistic relationship.
ContributorsAlattar, Zana (Author) / Graff, Sarah (Thesis director) / McClurg, Sharolyn (Committee member) / School of Molecular Sciences (Contributor) / School of Social Transformation (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Many bacteria actively import environmental DNA and incorporate it into their genomes. This behavior, referred to as transformation, has been described in many species from diverse taxonomic backgrounds. Transformation is expected to carry some selective advantages similar to those postulated for meiotic sex in eukaryotes. However, the accumulation of loss-of-function alleles at transformation loci and an increased mutational load from recombining with DNA from dead cells create additional costs to transformation. These costs have been shown to outweigh many of the benefits of recombination under a variety of likely parameters. We investigate an additional proposed benefit of sexual recombination, the Red Queen hypothesis, as it relates to bacterial transformation. Here we describe a computational model showing that host-pathogen coevolution may provide a large selective benefit to transformation and allow transforming cells to invade an environment dominated by otherwise equal non-transformers. Furthermore, we observe that host-pathogen dynamics cause the selection pressure on transformation to vary extensively in time, explaining the tight regulation and wide variety of rates observed in naturally competent bacteria. Host-pathogen dynamics may explain the evolution and maintenance of natural competence despite its associated costs.
ContributorsPalmer, Nathan David (Author) / Cartwright, Reed (Thesis director) / Wang, Xuan (Committee member) / Sievert, Chris (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
The relationship of attachment style to both the selection and efficacy of emotion management strategies in adult dyadic contexts is not well elucidated. In non-romantic contexts, the interplay between emotion management and individual attachment style may provide a better understanding of how affect can be mitigated in daily life. The present study investigated these interactions by studying 56 pairs of college age women who were close friends. Participants were asked to have a conversation about a current source of concern/distress to one partner, while seated in the laboratory. After the conversation, participants were asked to report their subjective experience of several emotions during the conversation, such as ‘sadness,’ ‘joy,’ and ‘fear.’ Participants were also asked to complete a questionnaire assessing adult attachment style, specifically attachment anxiety and avoidance. Behavior during the conversation was coded for co-rumination and co-cognitive reappraisal by the “listener.” Listener attachment insecurity showed a trending association with increased use of co-detached reappraisal, for both avoidance (p=0.14) and anxiety (p=0.14). Listener attachment insecurity also predicted lower use of co-rumination, for both anxiety (p=0.10) and avoidance (p=0.02). Speaker attachment insecurity moderated the relationship between co-detached reappraisal and speaker emotion. Greater co-detached reappraisal predicted higher reports of non-fear negative and positive emotions, but only for high-avoidance speakers. Greater co-detached reappraisal also predicted greater non-fear negative emotions among speakers high, but not low, on attachment anxiety. Greater listener use of co-positive reappraisal was associated with higher reports of speaker fear; this effect was not moderated by speaker attachment style. These findings are discussed in relation to theoretical conceptions of attachment style, and in terms of the impact of context on emotion.
ContributorsJakob, Nicholas (Co-author) / Tolmachoff, Georgeanne (Co-author) / Shiota, Michelle (Thesis director) / Luecken, Linda (Committee member) / Yee, Claire (Committee member) / School of Life Sciences (Contributor) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Human subject research is a sensitive ethical topic in today's society, and with good cause. The history of human subject research is full of tragedy and wrongdoing, which is what has led to the firm restrictions we presently have. At the same time, we also acknowledge the value behind human subject research and the information science can obtain from such endeavors. This project analyzes this conundrum through a narrative describing a group of scientists who choose to ignore some of the laws and regulations concerning human subject research in order to pursue neurological based research for a "greater good." In the novella, the scientists end up harming several people while performing their illegal research, but are able to obtain successful results. However, the group is eventually caught, and end up having to face the consequences of their actions. The situations and interactions the story presents are meant to juxtapose both sides of the human subject research ethical argument in a unique way in order to allow the reader to critically think through the argument themselves and form their own opinions on the matter.
ContributorsPirotte, Benjamin Daniel (Author) / Finn, Edward (Thesis director) / Cook, Paul (Committee member) / McGregor, Joan (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor) / School of Historical, Philosophical and Religious Studies (Contributor)
Created2015-05
Description
An introduction to neuroscientific thought aimed at an audience that is not educated in biology. Meant to be readable and easily understood by anyone with a high school education. The first section is completed in its entirety, with outlines for the proposed final sections to be completed over the next few years.
ContributorsNelson, Nicholas Alan (Author) / Olive, M. Foster (Thesis director) / Brewer, Gene (Committee member) / Barrett, The Honors College (Contributor) / Department of Psychology (Contributor) / School of Life Sciences (Contributor) / School of Historical, Philosophical and Religious Studies (Contributor)
Created2014-05
Description
In this study, we propose and then assess the efficacy of a new approach to static suspension to correct for facial paralysis. Our method involves placing barbed sutures through the superficial muscular aponeurotic system (SMAS) and anchoring them in the temporal fascia parallel to the underlying facial muscles. We first analyzed the ability of this procedure to improve facial symmetry by comparing the degree of asymmetry between the paralyzed and unaffected sides of a patient's face (N=10) prior to and following surgery. Then, to determine if symmetry is improved as a result of placing the sutures parallel to the direction of facial muscle forces, we measured the vectors of levator labii superioris and zygomaticus major in cadaver hemifaces (N=3) and compared them to the angles of the vectors of correction from the patient sample to angles of muscle vectors in three facial hemispheres from cadaver controls. Results indicate that: (1) facial symmetry was significantly improved in these patients and (2) this improvement. We conclude that, compared to existing protocols, our novel surgical method is a better means of static suspension for reconstruction following onset of facial paralysis as it is simple to perform, easy to replicate, able to be post-operatively adjusted in-office, has a good long-term prognosis, and, as we have demonstrated, effectively corrects the appearance of asymmetry by working with the underlying facial anatomy.
ContributorsLeach, Garrison Alecsander (Co-author) / Joganic, Jessica (Co-author) / Hooft, Nicole (Co-author) / Joganic, Edward (Co-author, Committee member) / Foy, Joseph (Thesis director) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
This paper encompasses part of the complex topic of relationships between consumers, organic products, and advertising in America with a particular focus on Tempe, Arizona. Background research included in this paper includes how the term "organic" was developed and regulated to fit the federal standards that are implied through the use of the USDA organic label that was introduced in October of 2002. Further research considers the factors that have empirically and overwhelmingly contributed to motivations of attitude development and purchasing behaviors of the average organic consumer in America, tracking changes and potential causes over the past several decades. A large proportion of this paper analyzes the results of a survey conducted in Tempe between late 2014 and early 2015. This survey, shown in the appendices, includes responses from 310 Tempe consumers regarding questions of demographics, knowledge and perception of organic products, perceived access to organic products, consumer values, and purchasing behaviors. The results of the survey reflect the values displayed in previous studies on national surveys, with some discrepancies that appear to set Tempe apart from the national average. However, the results of the survey are limited by their exclusion and limited parsing of multiple confounds. Additionally, the respondents of the survey were not proportionate to the actually population of Tempe and therefore cannot be accurately generalized to the Tempe population as a whole. The third and final section of this paper deals with the relationship between advertisers and consumers. This considers how advertising helps to develop product values and perceptions through various methods. Future directions for advertising of organic products is also addressed, as advertisers can potentially become a source of developing scientific information if properly utilized. Further directives and gaps in research are addressed in the final portion of the paper and include how to increase consumer knowledge, the problems faced by organic advocates, what is important about what we already know, and where to go from here.
ContributorsAttanasio, Amber-Leigh Lace (Author) / Brian, Jennifer (Thesis director) / Phillips, Elizabeth Capaldi (Committee member) / Barrett, The Honors College (Contributor) / Department of Psychology (Contributor) / School of Life Sciences (Contributor)
Created2015-05