Now showing items 16346-16365 of 20330

    • The role of sugar polyols in environmental stress protection

      Bohnert, Hans J.; Shen, Bo (The University of Arizona., 1997)
      Although the protective effects of polyols against environmental stress have been demonstrated, mechanisms through which protection is accomplished are unknown. In this dissertation, the potential functions of sugar polyols in osmotic stress protection have been investigated. The function of mannitol as a hydroxyl radical scavenger in plant cells has been tested by using a transgenic plant approach. The presence of mannitol in transgenic plant cells enhanced the hydroxyl radical scavenging capacity and protected phosphoribulokinase from oxidative inactivation. Transgenic plants showed increased resistance to methylviologen (MV)-induced oxidative stress, as documented by increased retention of chlorophyll in transgenic leaf tissue following MV treatment. In addition, mesophyll cells from transgenic plants exhibited higher CO₂ fixation than wild type. It was concluded that mannitol localized in chloroplasts can supplement endogenous radical scavenging mechanisms and reduce oxidative damage of cells by hydroxyl radicals. The role of polyols in osmotic adjustment was evaluated in yeast. A bacterial mannitol-1-phosphate dehydrogenase gene and an apple sorbitol-6-phosphate dehydrogenase gene were introduced into a glycerol-deficient yeast mutant. The presence of sorbitol and mannitol in transformants provided remarkable protection against salt stress. However, this protection was much less than the protection provided by the same concentration of glycerol in the transformants of glycerol-3-P dehydrogenase gene (GPD1). The reduced protection by mannitol and sorbitol suggested that osmotic adjustment by glycerol was either not sufficient for acquisition of salt tolerance or that glycerol had specific functions for which mannitol and sorbitol could not substitute. To understand the role of glycerol in salt tolerance, salt-tolerant suppressor mutants were isolated from the glycerol-deficient mutants. One such suppressor mutant, sr13, partially suppressed the salt-sensitive phenotype of the glycerol-deficient mutant, most likely, due to the double amount of K⁺ accumulated under salt stress. The accumulation of K⁺ and extrusion of Na⁺ in sr13 were not inhibited by a calcineurin inhibitor (FK506), suggesting SR13 may function downstream of the calcineurin signaling pathway or in a separate pathway that regulated ion homeostasis under salt stress.
    • Role of Surface Molecules in Campylobacter jejuni Colonization and Virulence in Chickens

      Joens, Lynn A.; Echevarría-Núñez, Lisbeth E.; Viswanathan, V. K.; Reggiardo, Carlos; Ravishankar, Sadhana; Joens, Lynn A. (The University of Arizona., 2012)
      Campylobacter spp. is one of the two major causes of foodborne illness throughout the world. Campylobacter accounts for the most common causes of diarrheal illness caused by bacterial pathogens worldwide and in the United States. It is estimated that Campylobacter diarrheal illness affects about 2.4 million persons every year with an estimated cost of treatment and loss of productivity exceeding $1 billion annually. Previous work in our laboratory on biofilms has demonstrated the presence pilus-like surface-associated structures disseminating from the cell wall of C. jejuni isolates not expressing flagella (flaAB mutants). To further investigate this finding, bioinformatics analysis, purification and identification of genes involved in the expression of surface-associated structures as well as mutational analysis of putative genes were performed. We identified two important poultry colonization factors in C. jejuni. These studies might provide insights in understanding the pathogenesis of C. jejuni. Moreover, it will provide a new target for potential vaccine development against C. jejuni infection in poultry production system. Thus directly impacting the number of C. jejuni infection in humans.
    • Role of Synaptic and Non-Synaptic Mechanisms Underlying Motor Neuron Control

      Fuglevand, Andrew J.; Revill, Ann; Bailey, E. Fiona; Fellous, Jean-Marc; Fregosi, Ralph; Levine, Richard; Fuglevand, Andrew J. (The University of Arizona., 2011)
      While motor neuron activity has been studied for many decades, the relative contribution of synaptic and non-synaptic mechanisms underlying this activity during natural behaviors is not well understood. Thus, the goal of this dissertation was to further understand the role of non-synaptic properties of motor neurons during voluntary activity. In particular, I considered three non-synaptic properties: persistent inward currents (PICs) that boost synaptic inputs, spike-threshold accommodation that affects recruitment threshold as excitation rates of rise slow, and spike-frequency adaptation that leads to a decrease in firing rate despite constant excitation levels. Computer simulations were employed to understand the potential effect that these properties could have on firing rate behavior. In particular, the focus was on paired motor unit recordings where a lower threshold motor unit’s firing rate served as a proxy for synaptic drive, and differences in firing rate (ΔF) were compared at a higher threshold unit’s recruitment and derecruitment. While ΔF has been used by others to estimate PIC activation, the simulation results indicated that each of these non-synaptic mechanisms could lead to positive ΔF. Furthermore, by varying contraction speed and duration it seemed possible to determine which property contributes to ΔF in vivo. The results from human experiments indicated that adaptation is most likely the predominant contributor to ΔF during natural behaviors. Additionally, positive ΔF was even observed in the genioglossus muscle of the tongue, where the role of PICs has been debated. These results suggested that ΔF may not the best method to detect PICs during natural behaviors. As such, I also considered whether there might be another metric to infer PIC activation during natural behaviors. Motor unit firing rates tend to plateau, or saturate, despite continued force increase, and one hypothesis is that PICs contribute to this behavior. Indeed, motor unit firing rate saturation was diminished by the addition of inhibition, which should have limited PIC activation. Therefore, this final study provided possible evidence for PIC activation during natural behaviors. Overall, this dissertation highlights that non-synaptic properties of motor neurons are activated during natural behaviors and that they contribute significantly to firing rate output.
    • The Role Of T Cells In Postmenopausal Hypertension

      Brooks, Heddwen; Pollow, Dennis, Jr.; Brooks, Heddwen; Lynch, Ronald; Konhilas, John; Frelinger, Jeffrey (The University of Arizona., 2016)
      The rate and severity of hypertension are much lower in women than men of a similar age. However, the incidence of hypertension and its complications increase dramatically after menopause, matching and then surpassing that of age-matched males. While current anti-hypertensive therapeutics can improve blood pressure in males, they have proven to be less effective in postmenopausal women. Clinical trials in menopausal women utilizing hormone replacement therapy have also produced controversial results, thus other approaches are necessary to control blood pressure in women after menopause. Targeting the endothelin system can attenuate hypertension in male mice, and components of this system are known to be upregulated in females after menopause. Recent evidence in male mice also demonstrates that T lymphocytes promote the development of hypertension. However, research into the role of the endothelin and immune systems during hypertension in females is lacking, and is necessary to better understand how blood pressure regulation changes after menopause and identify novel targets for anti-hypertensive drug development. Therefore, we sought to determine how the progression to menopause in the novel VCD mouse model of menopause impacts the degree of angiotensin II (Ang II) hypertension and whether antagonizing the ET-1 system could attenuate hypertension in menopausal animals. We also hypothesized that prevention of T cell-mediated responses contributes to sex differences in hypertension and that the increased degree of hypertension after menopause requires T cells. To determine how the gradual progression to menopause in VCD-treated mice impacts hypertension, we infused Ang II into premenopausal and VCD-treated peri- and postmenopausal animals. Compared to premenopausal mice, Ang II-induced hypertensive responses were significantly increased after menopause, but were unchanged during the perimenopause transition. 17𝛽-estradiol replacement during perimenopause prevented the increased hypertensive response in menopausal animals, demonstrating that upregulation of hypertension in this model is driven by the loss of estrogen-induced protective actions. To test the hypothesis that ETA receptor-mediated signaling promotes postmenopausal hypertension, VCD-treated menopausal mice were administered either the ETA receptor antagonist ABT-627, 17𝛽-estradiol replacement, or vehicle. The increased hypertensive response in menopausal mice was equally prevented by either ETA receptor antagonism or 17𝛽-estradiol replacement, supporting the notion that ET-1-targetted drugs may improve blood pressure control in postmenopausal women. To address the hypothesis that prevention of T cell-mediated responses contributes to sex differences in hypertension, Ang II was infused into T cell-deficient male and premenopausal or VCD-treated menopausal female Rag-1^(-/-) mice with or without CD3⁺ T cell adoptive transfer. The results support this hypothesis, demonstrating that T cells promote the increased hypertensive response in males, and that the T cell-dependent response is prevented in premenopausal females, establishing sex differences in hypertension. After menopause, T cells are required for the increase in hypertension. To test the hypothesis that anti-inflammatory regulatory T cells are required for resistance against hypertension in premenopausal females, PC-61 was administered to deplete regulatory T cells during 14 days of Ang II infusion. We found that regulatory T cell depletion significantly increased the degree of Ang II hypertension, supporting a critical anti-hypertensive role for regulatory T cells in premenopausal female mice.
    • Role of the Adaptive Immune System in Angiotensin II Induced Vascular Remodeling and Stiffening

      Larson, Douglas F.; Tawinwung, Supannikar; Vanderah, Todd W.; Lybarger, Lonnie P.; Larmonier, Nicolas; Larson, Douglas F. (The University of Arizona., 2013)
      Elevation of blood pressure leads to structural and functional alterations in vasculature, resulting in increased arterial stiffness, which in turn is a predictor of future hypertension and cardiovascular risks. Angiotensin II (Ang II) plays a crucial role in blood pressure regulation. In addition to its hemodynamic effects, Ang II activates both innate and adaptive immunity. The objective of this study is to define the roles of CD4⁺ T lymphocyte subsets in the progression of vascular remodeling and stiffening induced by Ang II. A mouse model of Ang II infusion was used to induce hypertension and vascular diseases. In the WT mice, Ang II infusion led to an increased aortic stiffness within 7 days of the treatment as well as an increase in aortic remodeling within 14 days of the treatment. Interestingly, RAG1(-/-) mice, lacking functional T and B lymphocytes were prevented from the vascular stiffening and remodeling caused by Ang II. Characterization of T cell subsets in the perivascular aortic infiltrates showed that there was a sequential activation of peri-arotic Th1 and Th17 during the time course of Ang II treatment, which was associated with the initial increased aortic stiffness and the subsequent remodeling, respectively. To extend the concept, roles of suppressive regulatory T cells (Tregs) were further examined. Proliferation of Tregs was successfully induced in vivo using a cytokine complex of IL-2 and anti-IL-2 mAb clone JES6-1. Ang II-infused mice that received the IL-2/anti-IL-2 complex exhibited a reduced vascular remodeling and stiffening caused by Ang II. Stimulation of Tregs with the IL-2/anti-IL-2 complex also suppressed the Th1 and Th17 responses and reduced immune cells infiltrates in the aortas. Since hypertension is closely related to the kidney and renal homeostasis is also tightly regulated by Ang II, the kidney function was determined in this Ang II-hypertensive model. In the wild type mice, two weeks infusion of Ang II resulted in an increased glomerular filtration rate (GFR) whereas immunodeficient RAG1(-/-) mice exhibited a marked decrease in GFR. Subsequent experiments showed that Th17 was crucial in renal hemodynamic response to Ang II, partly by regulating secretion of vasodilatory prostaglandin E₂.
    • THE ROLE OF THE ARIZONA STATE BOARD OF EDUCATION FROM 1961 THROUGH 1970

      Cool, Brent Alden, 1931- (The University of Arizona., 1971)
    • The role of the chorale in the oratorios and symphonies of Felix Mendelssohn-Bartholdy

      Chamberlain, Bruce; Holtan, Eric Howard (The University of Arizona., 2005)
      The Lutheran chorale fascinated Felix Mendelssohn-Bartholdy (1809-1947) to the extent that it became a signature element in some of his major works. The purpose of this study is to examine how and why he incorporated chorales and "pseudo-chorales" in three oratorios (Paulus, Op. 36, 1836; Elijah, Op. 70, 1846; Christus, Op. 97, 1847, unfinished), and two symphonies (#2 "Lobgesang" Op. 52, 1840; #5 "Reformation," 1830, Op. 107, publ. posth.) It also considers the effects of these issues on musical performance. Four influences upon Mendelssohn's inclusion of the chorale form are investigated: the music of J. S. Bach (1685--1750); Friedrich Schleiermacher (1768-1834, theologian); Johann Wolfgang von Goethe (1749-1832, author and poet); and Karl Friedrich Schinkel (1781-1841, painter and architect). The five works are analyzed in an attempt to illustrate how these influences led Mendelssohn to introduce chorales, with or without texts, with the intention of more fully engaging his audiences in the sacred drama the works produce, a supposition that has important implications for the musical phrasing, vocal color, articulation, dynamics, tempi, and momentum within and between movements. An over-arching purpose of this study is to provide a basis for more informed performances of Mendelssohn's oratorios and symphonies--a clearer understanding of his motives for including the chorale form is a logical beginning. While the influence of Bach's music on Mendelssohn--especially St. Matthew Passion with its extensive use of the chorale--is generally accepted, there is much debate about Mendelssohn's theological proclivities and their influence on his music. Mendelssohn's letters indicate that it is Schleiermacher's Christo-centric theology--not a Jewish or humanistic approach as propounded by other--that explains Mendelssohn's faith and explicates one of the motivations/purposes in his life. The comprehension of this motivation, especially relating to his use of chorales, is prerequisite to the effective interpretation of Mendelssohn's chorale-based works. Goethe and Schinkel, as leaders of the neoclassical trend in the arts and undeniable influences on Mendelssohn, provided additional encouragement for Mendelssohn's employment of the older musical form. This formative confluence led Mendelssohn to adopt the chorale as the emblem of his musical, theological, and philosophical ideals.
    • The role of the community level worker in Papago Indian development

      Van Willigen, John (The University of Arizona., 1971)
    • The role of the cytoskeleton in protein body formation in maize endosperm cells

      Larkins, Brian A.; Clore, Amy Menning, 1969- (The University of Arizona., 1997)
      The proper distribution of proteins is important for the development and function of both individual cells and whole organisms. Relatively little is known about the mechanisms of protein localization in plant cells. Protein body formation in maize endosperm provides a useful system in which to study these mechanisms. Maize endosperm is a specialized tissue that accumulates starch and storage proteins and ultimately provides nutrients for the germinating seedling. The storage proteins, called zeins, are cotranslationally inserted into the rough endoplasmic reticulum (RER) where they aggregate into spherical protein bodies. Previous studies have suggested that the cytoskeleton may play a role in protein body formation, since actin, the protein synthesis factor EF-1α (which associates with the cytoskeleton in other systems), and polysomes, including zein polysomes, were found associated with protein bodies following endosperm homogenization. To determine whether the cytoskeleton, EF-1α, and protein bodies are associated in situ, these components were visualized in intact endosperm cells. By using indirect immunofluorescence and confocal microscopy, changes were documented in the distributions of EF-1α, actin, and microtubules during development. The protein bodies are found enmeshed in EF-1α and actin and are juxtaposed with a multidirectional array of microtubules. In addition, actin and EF-1α appear to exist in a complex. Finally, actin bundling assays demonstrated that maize EF-1α is capable of bundling actin in vitro. Therefore, EF-1α may organize actin around protein bodies. One possible role of the cytoskeletal network around protein bodies is the transport and or anchoring of zein mRNAs to sites of protein body formation. To test this hypothesis, in situ hybridization experiments were conducted in the presence and absence of cytoskeleton disrupting agents. The results suggest that while the zein mRNAs may associate with the RER at random sites, a cytoskeleton-dependent transport mechanism may be utilized to traffick them to the RER surface. To more convincingly demonstrate a role of the cytoskeleton in zein mRNA localization, microinjection and visualization of zein mRNAs in the presence and absence of intact cytoskeletal elements is required. Methods for microinjecting maize endosperm cells with such mRNAs were devised and preliminary results are described.
    • THE ROLE OF THE ERYTHROCYTE IN THE TRANSMISSION AND PATHOGENESIS OF MURINE LEUKEMIAS

      Reilly, Christopher Aloysius, 1942- (The University of Arizona., 1968)
    • THE ROLE OF THE FEDERAL GOVERNMENT IN HISTORIC PRESERVATION

      Somers, Gary Fred (The University of Arizona., 1979)
    • THE ROLE OF THE HIGH SCHOOL DEPARTMENT CHAIRMAN

      Sovereign, Keith Morton, 1936- (The University of Arizona., 1969)
    • THE ROLE OF THE HIGH SCHOOL PRINCIPAL IN CURRICULUM DEVELOPMENT

      Afandī, Muḥammad Muḥammad Ḥāmid (The University of Arizona., 1962)
    • Role of the interface in metal solvent extraction kinetics.

      Chamupathi, Virittamulla Gamage. (The University of Arizona., 1987)
      Interfacially active reagents are utilized in metal solvent extraction processes and it is therefore important to understand the role of the liquid-liquid interface in the study of the kinetics and equilibria of extraction. The diffusion problems encountered in the traditional apparatus were overcome by using a high speed stirring apparatus. The microporous teflon membrane phase separator permitted more accurate measurements of interfacial areas, characterization of extraction kinetics of metal chelates, and a greater understanding of the phase separation mechanism. In contrast to the neutral ligands, the anionic ligand of dithizones and substituted dithizones showed significant interfacial adsorption at the chloroform/water interface as monitored spectro-photometrically. Equilibrium studies on p-halodithizones indicated that the adsorption constant increased as the substituent was altered from chloro to bromo to iodo, and with the distribution ratio of the ligand. Kinetic studies on dithizone and p-iododithizone with Ni(II) and Zn(II) indicated that the extent of participation of the interface in solvent extraction kinetics of these metal ions is dictated by the interfacial activity of the extractant and the mechanisms of the rate limiting step in the bulk aqueous and interfacial regions.
    • The role of the interface in the kinetics and mechanism of liquid-liquid extraction.

      Freiser, Henry; Dietz, Mark L.; Salzman, W. R.; Burke, M. F.; Fernando, Quintus; Miller, Walter B. (The University of Arizona., 1989)
      When solutions of various metal 8-quinolinolates or beta-diketonates in an organic solvent were contacted with an aqueous phase and vigorously stirred to generate a large interfacial area, a reversible decrease in the organic phase concentration of the complex was observed. The magnitude of this decrease varied with interfacial area, solvent, temperature, and the nature and concentration of the complex. Analysis of the phenomenon using the Langmuir isotherm showed that the concentration change may be explained by adsorption of significant quantities of the complexes at the increased liquid-liquid interface generated by stirring. Such adsorption was found to complicate extraction kinetics measurements using the high-speed stirring technique when the product chelate is interfacially active, distorting the absorbance/time profile from which rate constants are derived, altering the interfacial area in the reaction vessel, and displacing reactant molecules from the interface. Neutral surfactants were observed to have similar effects. Chelate adsorption was also demonstrated to affect metal ion extraction equilibria, shifting the pH 1/2 value associated with a given metal ion. The magnitude of this shift was found to depend on the concentration of the chelate, its interfacial adsorption constant, and interfacial area. Differences in the pH 1/2 shift were shown to serve as a means of separating metal ions. Studies of the rate of nickel extraction by 8-quinolinols showed that the distribution constant and interfacial activity of the ligand are important factors governing the balance between bulk and interfacial pathways in the extraction. The interfacial rate constant for a given ligand was independent of organic solvent and was typically 10 times larger than the corresponding bulk value, indicating that the interface, although essentially aqueous in character, is a more conducive medium for the reaction of the metal ion and ligand.
    • ROLE OF THE INTERFACE IN THE KINETICS AND MECHANISM OF SOLVENT EXTRACTION SYSTEMS (DITHIZONE, OXINE, INTERFACIAL AREA, DISPERSION).

      Freiser, Henry; APRAHAMIAN, EDWARD, JR. (The University of Arizona., 1985)
      A high speed stirring apparatus was constructed for following the kinetics of metal ion extraction by chelating agents. The semi-automated system is capable of measuring reactions with half lives of 20 seconds or more with data being collected every second. Experimental data obtained with the device are superior to those collected by batch shakers, fixed interface cells, falling drop, or other stirring devices. The use of a microporous Teflon membrane phase separator along with the thermodynamic relation, the Gibbs Equation, enabled the measurement of drop sizes in a two phase liquid-liquid dispersion. This allowed the determination of the quantity of interfacial area as a function of stir rate. The effect of interfacial area on the rate of extraction of five different chelating agents with various divalent metal ions was determined in this study. The role of the interfacial area in extraction kinetics was found in a system where diffusional effects are negligible. This information provides an answer to the question of whether the rate determining step of extraction occurs in either the bulk aqueous phase or in the interfacial region. The proportionality between rate and specific interfacial area was employed to find the magnitude of the contributions of the bulk and interfacial components and also allowed the calculation of the individual rate constants. Evaluation of the bulk and interfacial rate constants yields important fundamental information as to the chemical nature and differences between the chloroform/water interface and the bulk aqueous phase. The results appear to illustrate that the interface is a more conducive medium for reaction between metal and ligand than the aqueous phase. The role of foreign species, namely nonionic surfactants, on the rate of extraction was investigated to explore their applicability in solvent extraction. Nonionic surfactants were found to enhance the rates of extraction to different extents in different metal systems.
    • The Role of the Left Temporal Lobe in Naming and Semantic Knowledge

      Beeson, Pelagie M; Antonucci, Sharon Mary; Beeson, Pelagie M; Katsanis, Emmanuel; Lybarger, Lonnie; Riggs, Michael W.; So, Magdalene (The University of Arizona., 2005)
      Background: Anomia is often demonstrated by individuals who sustain damage to the left inferior temporal lobe. The nature of the anomia in individuals with damage to anterior regions of the left temporal lobe (BA 38, 21, 20) has been associated with degradation to semantic knowledge (semantic anomia), while damage to regions farther posterior (BA 37) has been associated with disconnection between preserved semantic knowledge and access to phonological word forms (pure anomia). However, evidence of semantic anomia often comes from individuals with cortical damage that extends beyond left temporal regions, so that it remains unclear whether unilateral damage to this area will result in semantic degradation. Aims: The aim of this study was to examine naming performance in individuals with focal damage to anterior versus posterior regions of the left inferior temporal lobe to determine whether there is a difference in the nature of the observed anomia. Methods: Eight individuals who underwent left anterior temporal lobectomy (L ATL) and eight individuals who sustained left posterior cerebral artery infarcts (L PCA) completed a battery of language measures that assessed lexical retrieval and semantic processing. Sixteen age-and-education matched controls also completed this battery. High resolution structural brain scans were collected for each individual who sustained brain damage. Performance on behavioral measures was examined relative to lesion size and location using statistical analyses. Results: Naming performance ranged from severely impaired to unimpaired in both groups of brain damaged individuals. Both the L ATL and L PCA groups demonstrated well preserved semantic knowledge during lexical retrieval tasks and assessments of semantic knowledge. Naming performance was correlated with lesion volume. Furthermore, a relationship between percent damage to inferior temporal regions, BAs 20 and 21, and naming performance was observed. Conclusion: The behavioral and neuroanatomical evidence indicated that individuals with unilateral damage to left inferior temporal cortex, regardless of anterior versus posterior lesion location, do not demonstrate semantic anomia. These findings suggest that, even in the presence of severe naming impairment, unilateral damage to left inferior temporal cortex is not sufficient to significantly degrade semantic knowledge.
    • The role of the mitochondrial thioredoxin-2 system in cell function

      Powis, Garth; Nonn, Larisa (The University of Arizona., 2003)
      The hypothesis upon which this research is based is that the mitochondrial thioredoxin-2 system, which consists of mitochondrial thioredoxin-2 (Trx-2), mitochondrial thioredoxin reductase (TrxR-2) and mitochondrial thioredoxin peroxidase (Prdx-3), protects cells against apoptosis and regulates cell growth via mitochondrial redox homeostasis. Trx-2 mRNA was found expressed in a panel of cancer cell lines and Trx-2 protein is localized exclusively to the mitochondria. An alternate splice form of Trx-2 lacking exon 2 was identified that does not yield protein. Forced overexpression of Trx-2 in cell lines by using constitutive and inducible promoter systems increased mRNA levels, but did not yield an increase in Trx-2 protein. The role of Trx-2 in mammalian development was examined by generating a mouse deficient in Trx-2. Massive apoptosis, exencephaly and early embryonic lethality was seen in the Trx-2(-/-) homozygous embryos. Trx-2(-/-) embryonic fibroblasts were not viable under normal growth conditions, but could be rescued with maintenance in hypoxia. Trx-2(-/-) cells were also lacking mature cytochrome c, implicating Trx-2 in cytochrome c biogenesis. The Trx-2(+/-) heterozygous mice, which appear normal, had an increased sensitivity to some forms of oxidative toxicity (eg. acute doxorubicin) compared to the wild-type mice. To investigate the role of Prdx-3, WEHI7.2 cells with overexpression of Prdx-3 were generated by stable transfection. Overexpression of Prdx-3 inhibited cell proliferation, reduced cellular hydrogen peroxide levels and altered the mitochondrial membrane potential. Prdx-3 overexpression protected the cell from various drug-induced and hypoxia-induced apoptosis. Prdx-3 protein degradation was decreased during hypoxia, leading to a longer half-life under hypoxic conditions. Additionally, Prdx-3 protein levels were increased in a RCC4 cells expressing wild-type VHL compared to RCC4 cells with mutant VHL.
    • The Role of the Monkey Amygdala in the Autonomic Expression of Emotion

      Gothard, Katalin M.; Spitler, Kevin M.; Gothard, Katalin M.; Fugelvand, Andrew; Nadel, Lynn; Allen, John J.B. (The University of Arizona., 2007)
      The skin conductance response is involved in the preparation for and response to stimuli with emotional significance. The neural mechanisms responsible for the generation of the skin conductance response are not well understood despite the common use of this signal as an index of emotional response. Data from anatomical, lesion, and neuroimaging studies in humans suggest that the amygdala, a component of the brain circuit for emotion, plays a critical role in the generation of the skin conductance response. Here we employ a novel combination of existing techniques to understand the stimuli that elicit skin conductance responses in the monkey and the neural mechanisms in the amygdala that participate in its generation. We recorded skin conductance responses in monkeys trained to perform a passive image viewing task. This paradigm is a staple of human emotion research but to date has not been adapted to the monkey. In addition, skin conductance responses to these stimuli were recorded in conjunction with single unit responses from the amygdala. This study addresses the relationship between the activity of single neurons recorded from identified nuclei of the monkey amygdala and autonomic responses. Neurons in multiple nuclei of the amygdala showed reliable changes in neuronal discharge prior to the skin conductance response. These neurons were primarily in the dorsal nuclei of the amygdala, which confirms predictions made from anatomical and neuroimaging data. It is suggested that these changes in neuronal discharge may correspond to the generation of this autonomic component of the expression of emotion.