Many fish species respond to cold temperatures by inducing mitochondrial biogenesis, reflected in an increase in the activity of the mitochondrial enzyme cytochrome c oxidase (COX). COX is composed of 13 subunits, 3 encoded by mtDNA and 10 encoded by nuclear genes. I used thermal acclimation/winter acclimatization to explore how fish muscle controls the synthesis of COX. In this study, I used real-time PCR to measure mRNA levels for the 10 nuclear-encoded COX genes and several transcriptional regulators. I compared the thermal response of two cyprinid species, the tropical zebrafish (Danio rerio, acclimated to 11 and 30°C) and the temperate redbelly dace (Phoxinus eos, winter and summer acclimatized). I hypothesized that (i) there would be an increase in COX activity in the cold- versus warm-acclimated fish and (ii) changes in COX activity would be paralleled in the transcript levels of the nuclear-encoded COX subunits as well as the master-regulators and transcription factors of mitochondrial biogenesis. Zebrafish COX activity did not change in the cold but the transcript levels of some subunits decreased up to 70%. Redbelly dace COX activity was 2.9-fold higher in winter fish and though nuclear-encoded subunits had higher transcript levels the increases did not parallel enzyme activity, ranging from 1.7- to 21-fold higher in winter. There also did not appear to be parallel patterns in mRNA for the transcriptional regulators. In zebrafish, when COX activity did not change, there was no significant change in PGC-1α mRNA. In redbelly dace, when COX activity was 2.9-fold higher, PGC-1α mRNA was 6.3-fold higher. These observations suggest that coordination of COX subunit expression is imperfect, implying that subsets of these genes are more important in determining the COX activity. I assert that those genes that are most likely the candidates for regulating COX activity are COX4 and COX5A as they are the first regulatory subunits incorporated into the holoenzyme. Though arguments can also be made for COX5B, 6A and 7B based on the parallels between changes in enzyme activity and transcript abundance as well as the position in which they are assembled into the enzyme complex. / Thesis (Master, Biology) -- Queen's University, 2010-08-10 11:35:35.352

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Fibroblast growth factor-2 (FGF-2) is expressed as high molecular weight (> 20 kDa, Hi-FGF-2), or low molecular weight, (18 kDa, Lo-FGF-2) isoforms with distinct functions in the heart and other tissues. Studies to-date have focused on Lo-FGF-2, while the biology of Hi-FGF-2 is less well understood. This work investigated potential autocrine and paracrine effects of rat and human Hi-FGF-2 on cardiac myocytes and non-myocytes (myofibroblasts). Using rat ventricular myofibroblast cultures stimulated with angiotensin II (Ang II), in the absence or presence of YVAD, a peptide inhibitor of caspase-1, it was shown that caspase-1 activity was required for the Ang II-stimulated Hi-FGF-2 secretion. Secreted rat Hi-FGF-2 was shown to be biologically active and capable of stimulating neonatal as well as adult cardiomyocyte hypertrophy in vitro. The effect of extracellular-acting Hi- versus Lo-FGF-2 on the secretome profile of rat cardiac myofibroblasts was compared. Conditioned media collected after stimulation with rat Hi- or Lo-FGF-2 were analyzed by mass spectroscopy (LC-MS/MS). Secretome profiles suggested that Hi-FGF-2 was more potent than Lo-FGF-2 in upregulating several matricellular and fibrosis-associated proteins, most prominently periostin, follistatin-like protein 1, plasminogen activator inhibitor-1, and tenascin. Human heart (atrial) tissue, pericardial fluid, and human heart-derived myofibroblasts were shown to accumulate predominantly Hi-FGF-2. Ang II up-regulated Hi-FGF-2 in human cells, via activation of: type 1 or type 2 Ang II receptors (AT-1R, AT-2R); the ERK pathway; and matrix metalloprotease-2. Neutralizing antibodies specific for Hi-FGF-2 (neu-AbHi-FGF-2) reduced expression of proteins associated with fibroblast-to-myofibroblast conversion and fibrosis. Blocking the autocrine action of Hi-FGF-2 on human cells with neu-AbHi-FGF-2 resulted in down-regulation of periostin, as well as α-smooth muscle actin, pro-collagen, embryonic smooth muscle myosin, and extra domain A fibronectin, consistent with a reversal from activated myofibroblast to fibroblast phenotype. Stimulation of human myofibroblasts with human Hi-FGF-2 was significantly more potent than Lo-FGF-2 in upregulating pro-interleukin-1β and plasminogen activator inhibitor-1, considered to be pro-inflammatory proteins. It is concluded that exported, extracellular-acting Hi-FGF-2 has pro-fibrotic, pro-inflammatory, and pro-hypertrophic properties, contributes to the ‘activated fibroblast’ phenotype, and represents a therapeutic target for prevention of maladaptive cardiac remodeling in humans.

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 158-182). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 158-182). Also available on the Internet.

Thesis (M.S.)--California Polytechnic State University, 2009. / Title from PDF title page; viewed on September 25, 2009. Major professor: Scott Hazelwood, Ph.D. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Engineering with a specialization in Biomedical Engineering." "September 2009." Includes bibliographical references (p. 72-74). Also available on microfiche.

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2010. / Committee Chair: Rudy Gleason; Committee Member: Raymond Vito; Committee Member: W. Robert Taylor. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (M.Phil.) - University of Queensland, 2005. / Includes bibliography.