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Description
In somatic cells, the mitotic spindle apparatus is centrosomal and several isoforms of Protein Kinase C (PKC) have been associated with the mitotic spindle, but their role in stabilizing the mitotic spindle is unclear. Other protein kinases such as, Glycogen Synthase Kinase 3â (GSK3â) also have been shown to be associated with the mitotic spindle. In the study in chapter 2, we show the enrichment of active (phosphorylated) PKCæ at the centrosomal region of the spindle apparatus in metaphase stage of 3T3 cells. In order to understand whether the two kinases, PKC and GSK3â are associated with the mitotic spindle, first, the co-localization and close molecular proximity of PKC isoforms with GSK3â was studied in metaphase cells. Second, the involvement of inactive GSK3â in maintaining an intact mitotic spindle was shown. Third, this study showed that addition of a phospho-PKCæ specific inhibitor to cells can disrupt the mitotic spindle microtubules. The mitotic spindle at metaphase in mouse fibroblasts appears to be maintained by PKCæ acting through GSK3â. The MAPK pathway has been implicated in various functions related to cell cycle regulation. MAPKK (MEK) is part of this pathway and the extracellular regulated kinase (ERK) is its known downstream target. GSK3â and PKCæ also have been implicated in cell cycle regulation. In the study in chapter 3, we tested the effects of inhibiting MEK on the activities of ERK, GSK3â, PKCæ, and á-tubulin. Results from this study indicate that inhibition of MEK did not inhibit GSK3â and PKCæ enrichment at the centrosomes. However, the mitotic spindle showed a reduction in the pixel intensity of microtubules and also a reduction in the number of cells in each of the M-phase stages. A peptide activation inhibitor of ERK was also used. Our results indicated a decrease in mitotic spindle microtubules and an absence of cells in most of the M-phase stages. GSK3â and PKCæ enrichment were however not inhibited at the centrosomes. Taken together, the kinases GSK3â and PKCæ may not function as a part of the MAPK pathway to regulate the mitotic spindle.
ContributorsChakravadhanula, Madhavi (Author) / Capco, David G. (Thesis advisor) / Chandler, Douglas (Committee member) / Clark-Curtiss, Josephine (Committee member) / Newfeld, Stuart (Committee member) / Arizona State University (Publisher)
Created2012
Description
First-semester student retention is a constant priority for undergraduate institutions. The transition to the collegiate level, and to a new scholastic program and format, is frequently challenging academically and socially—for this reason, many first-semester course schedules for incoming freshman undergraduates feature an introductory seminar to ease transition to an undergraduate lifestyle. Arizona State University features a required “Careers in the Life Sciences” course for its first-semester School of Life Sciences students, which has had tractable results in first semester student retention and academic success. Here, we evaluate a component of the seminar, the peer-mentorship program, for its efficacy in students’ first semester experience. Analysis of self-reports from 168 first-semester “mentees” and their 25 mentors indicates frequency of mentee-mentor contact was the best indicator of a higher first semester GPA, comfort with academic resources and study habits, and desire to engage in extracurricular activities and internships. These data indicate that access to a mentor who actively engages and verbally connects with their mentees is a valuable component of first-semester student academic integration and retention.
ContributorsMathews, Ian T. (Author) / Capco, David (Thesis director) / Clark-Curtiss, Josephine (Committee member) / Harrell, Carita (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2014-05