Biology Commons^™

Intraspecific Variation In Two Cosmopolitan Myxomycetes, Didymium Squamulosum And Didymium Difforme (Physarales: Didymiaceae), Katherine Elizabeth Winsett

Graduate Theses and Dissertations

The myxomycetes (plasmodial slime molds or myxogastrids) are one of three groups considered to be true slime molds (class Eumycetozoa sensu Olive 1975). Two vegetative states--amoebae and plasmodia--along with a spore-producing fruiting body characterize the life cycle of the myxomycetes. These organisms are associated with decaying plant material and are found in all terrestrial habitats worldwide. A number of species are considered cosmopolitan, being found worldwide, where they are associated with a diversity of microhabitats and substrates. A review of the literature, including molecular investigations in all three groups of slime molds, is presented, and this is followed by four …

Preliminary Characterization Of Mitochondrial Atp-Sensitive Potassium Channel (Mitokatp) Activity In Mouse Heart Mitochondria, Venkat Raghav Aachi

Dissertations and Theses

Myocardial ischemia, infarction, heart failure and arrhythmias are the manifestations of coronary artery disease. Reduction of ischemic damage is a major concern of cardiovascular biology research. As per recent studies, the mitochondrial ATP-sensitive potassium channel (mitoK_ATP) opening is believed to play key role in the physiology of cardioprotection, protection against ischemia-reperfusion injury or apoptosis. However, the structural information of mitoK_ATP is not precisely known. Elucidating the structural integrity and functioning of the mitoK_ATP is therefore a major goal of cardiovascular biology research. The known structure and function of the cell ATP-sensitive potassium channel (cellK_ATP) …

How Do Animal Mitochondria Tolerate Water Stress?, Michael A. Menze, Steven C. Hand

Faculty Research & Creative Activity

The vast majority of animal species do not tolerate severe water stress, but the encysted embryo of the brine shrimp Artemia franciscana is an exceptionally useful organism to investigate physiological mechanisms for enduring extreme environmental insults. Any substantial reduction in cellular water poses a threat to survival. Nevertheless anhydrobiotic animals survive virtually complete loss of cellular water. The mechanisms that govern “life without water” (anhydrobiosis) are still not well understood. With certain exceptions, it seems that a recurring strategy for tolerating severe water loss involves the accumulation of both low molecular weight solutes (e.g. trehalose or other polyol) and highly …

How Do Animal Mitochondria Tolerate Water Stress?, Michael Menze, Steven Hand

Faculty and Staff Scholarship

The vast majority of animal species do not tolerate severe water stress, but the encysted embryo of the brine shrimp Artemia franciscana is an exceptionally useful organism to investigate physiological mechanisms for enduring extreme environmental insults. Any substantial reduction in cellular water poses a threat to survival. Nevertheless anhydrobiotic animals survive virtually complete loss of cellular water. The mechanisms that govern “life without water” (anhydrobiosis) are still not well understood. With certain exceptions, it seems that a recurring strategy for tolerating severe water loss involves the accumulation of both low molecular weight solutes (e.g. trehalose or other polyol) and highly …

Substrate And Regulation Of Mitochondrial Μ-Calpain, Aashish Joshi

University of Kentucky Doctoral Dissertations

μ -Calpain is localized to the mitochondrial intermembrane space. Apoptosisinducing factor (AIF), which executes caspase-independent cell death, is also localized to the mitochondrial intermembrane space. Following processing at the N-terminus, AIF becomes truncated (tAIF) and is released from mitochondria. The protease responsible for AIF processing has not been established. The same submitochondrial localization of mitochondrial μ-calpain and AIF gives support to the hypothesis that mitochondrial μ-calpain may be responsible for processing AIF. Atractyloside-induced tAIF release in rat liver mitochondria was inhibited by cysteine protease inhibitor MDL28170, but not by calpain inhibitors PD150606 or calpastatin. Moreover, μ-calpain immunoreactivity was difficult to …

Cardioprotective Signal Transduction To Mitochondria, Casey Lee Quinlan

Dissertations and Theses

Intracellular responses to external stimuli require reception of the message at the plasma membrane followed by encoding and transmission of the message to its effectors downstream. In this process, diverse cellular responses are mediated by many redundant molecular players. The apparent generality and redundancy of many kinases, such as the mitogen-activated protein kinases (MAPKs), suggests that signal transduction must gain specificity through tight regulation. Diffusion and random collisions of relevant signaling components seem insufficient to explain the multilayered complexity observed in cell signaling cascades. Emerging hypotheses suggest that signaling machinery may achieve enhanced specificity and control by exploiting the compartmentalization …

Effect Of Redox-Cycling Agents On Nitric Oxide Synthase Activity In Vitro And Modulation Of Protein Expression In Vivo: No Nitric Oxide Synthase In Mitochondria, Priya Venkatakrishnan

Open Access Theses & Dissertations

This Dissertation describes studies conducted in three areas dealing with the interaction of redox-active compounds with the flavin- and heme- containing enzyme, neuronal nitric oxide synthase (NOS). They are as follows:

I. Studies were initiated using extracts from several varieties of tobacco to identify constituent(s) that could interact with nNOS. Results from [¹⁴C]-L-arginine to [¹⁴C]-L-citrulline conversion assays to which tobacco extracts were individually added, indicate that there are nNOS inhibitors present in tobacco and they are non-polar, lipophilic and non-volatile in nature. In addition, results from assays in which the tobacco-derived redox-active compound, 2,3,6- …

Mitochondrial Biogenesis: Is An Old Dog Still Teaching Us New Tricks? Meeting On The Assembly Of The Mitochondrial Respiratory Chain, Rosemary A. Stuart, Peter Rehling

Biological Sciences Faculty Research and Publications

No abstract provided.

The Long And Winding Road: Influences Of Intracellular Metabolite Diffusion On Cellular Organization And Metabolism In Skeletal Muscle, Stephen T. Kinsey, Kristin M. Hardy, Bruce R. Locke

Biological Sciences

A fundamental principle of physiology is that cells are small in order to minimize diffusion distances for O₂ and intracellular metabolites. In skeletal muscle, it has long been recognized that aerobic fibers that are used for steady state locomotion tend to be smaller than anaerobic fibers that are used for burst movements. This tendency reflects the interaction between diffusion distances and aerobic ATP turnover rates, since maximal intracellular diffusion distances are ultimately limited by fiber size. The effect of diffusion distance on O₂ flux in muscle has been the subject of quantitative analyses for a century, but the …

Ultrafine Particle Initiation Of Lipid Peroxidation In Mitochondria, Josephine Kimberly Wells

Undergraduate Honors Theses

Studies have shown that car exhaust particles increase cellular oxidative stress (Li, 2002), and people who live in highly polluted areas have shown a higher incidence of cardiovascular disease (Beck, 2005). Recently a theory has been developed that ultrafine particles (< 0.1 µm in diameter) contained in the atmospheric pollution are responsible for initiating the adverse effects of damage and disease (Li, 2003).

Ultrafine particles (UFP), which make up 72% of the particle concentration in the air (Beck, 2005), typically originate from sources involving combustion, such as cars, forest fires, volcanoes and industry (USDHHS, 1995). The small size and abundance of UFPs provide ample surface area with an increased absorption for damaging substances such as iron or reactive organic compounds (Beck, 2005; …

A Reaction–Diffusion Analysis Of Energetics In Large Muscle Fibers Secondarily Evolved For Aerobic Locomotor Function, Kristin M. Hardy, Bruce R. Locke, Marilia Da Silva, Stephen T. Kinsey

Biological Sciences

The muscles that power swimming in the blue crab, Callinectes sapidus, grow hypertrophically, such that in juvenile crabs the cell diameters are

Does Intracellular Metabolite Diffusion Limit Post-Contractile Recovery In Burst Locomotor Muscle?, Stephen T. Kinsey, Pragyansri Pathi, Kristin M. Hardy, Amanda Jordan, Bruce R. Locke

Biological Sciences

Post-metamorphic growth in the blue crab entails an increase in body mass that spans several orders of magnitude. The muscles that power burst swimming in these animals grow hypertrophically, such that small crabs have fiber diameters that are typical of most cells (600μm). Thus, as the animals grow, their muscle fibers cross and greatly exceed the surface area to volume ratio (SA:V) and intracellular diffusion distance threshold that is adhered to by most cells. Large fiber size should not impact burst contractile function, but post-contractile recovery may be limited by low SA:V and excessive intracellular diffusion distances. A number of …

Trehalose Loading Through The Mitochondrial Permeability Transition Pore Enhances Desiccation Tolerance In Rat Liver Mitochondria., Xiang-Hong Liu, Alptekin Aksan, Michael Menze, Steven Hand, Mehmet Toner

Faculty and Staff Scholarship

Trehalose has extensively been used to improve the desiccation tolerance of mammalian cells. To test whether trehalose improves desiccation tolerance of mammalian mitochondria, we introduced trehalose into the matrix of isolated rat liver mitochondria by reversibly permeabilizing the inner membrane using the mitochondrial permeability transition pore (MPTP). Measurement of the trehalose concentration inside mitochondria using high perfOrmance liquid chromatography showed that the sugar permeated rapidly into the matrix upon opening the MPTP. The concentration of intra matrix trehalose reached 0.29 mmoVmg protein (-190 mM) in 5 min. Mitochondria, with and without trehalose loaded into the matrix, were desiccated in a …

Yeast Oxa1 Interacts With Mitochondrial Ribosomes: The Importance Of The C‐Terminal Region Of Oxa1, Lixia Jia, Mary Kathryn Dienhart, Mark Schramp, Matthew Mccauley, Kai Hell, Rosemary A. Stuart

Biological Sciences Faculty Research and Publications

The yeast mitochondrial Oxa1 protein is a member of the conserved Oxa1/YidC/Alb3 protein family involved in the membrane insertion of proteins. Oxa1 mediates the insertion of proteins (nuclearly and mitochondrially encoded) into the inner membrane. The mitochondrially encoded substrates interact directly with Oxa1 during their synthesis as nascent chains and in a manner that is supported by the associated ribosome. We have investigated if the Oxa1 complex interacts with the mitochondrial ribosome. Evidence to support a physical association between Oxa1 and the large ribosomal subunit is presented. Our data indicate that the matrix‐exposed C‐terminal region of Oxa1 plays an important …

Insertion Of Proteins Into The Inner Membrane Of Mitochondria: The Role Of The Oxa1 Complex, Rosemary A. Stuart

Biological Sciences Faculty Research and Publications

The inner mitochondrial membrane harbors a large number of proteins that display a wide range of topological arrangements. The majority of these proteins are encoded in the cell's nucleus, but a few polytopic proteins, all subunits of respiratory chain complexes are encoded by the mitochondrial genome. A number of distinct sorting mechanisms exist to direct these proteins into the mitochondrial inner membrane. One of these pathways involves the export of proteins from the matrix into the inner membrane and is used by both proteins synthesized within the mitochondria, as well as by a subset of nuclear encoded proteins. Prior to …

Oxa1p Acts As A General Membrane Insertion Machinery For Proteins Encoded By Mitochondrial Dna, Kai Hell, Walter Neupert, Rosemary A. Stuart

Biological Sciences Faculty Research and Publications

Oxa1p is a member of the conserved Oxa1/YidC/Alb3 protein family involved in the membrane insertion of proteins. Oxa1p has been shown previously to directly facilitate the export of the N‐terminal domains of membrane proteins across the inner membrane to the intermembrane space of mitochondria. Here we report on a general role of Oxa1p in the membrane insertion of proteins. (i) The function of Oxa1p is not limited to the insertion of membrane proteins that undergo N‐terminal tail export; rather, it also extends to the insertion of other polytopic proteins such as the mitochondrially encoded Cox1p and Cox3p proteins. These are …

Isolation And Characterization Of Four Linear Plasmids In Ascosphaera Aggregata, Dakun Xu

Biology

Four extrachromosomal DNA plasmids were isolated from the entomopathogenic fungus Ascosphaera aggregata and named as pAaL10, pAaL8, pAaL2.8, and pAaL2.6 based on their host, morphology and size. DNA hybridization results suggested that pAaL10, pAaL8, pAaL2.8, and pAaL2.6 are not homologous with pAaL, a plasmid isolated from Ascosphaera apis. Extraction of DNA from intact mitochondria followed by gel electrophoretic analysis suggests pAaL10, pAaL8, pAaL2.8, and pAaL2.6 are located within the mitochondria. From hybridization results it was concluded that each of pAaL10, pAaL8, pAaL2.8, and pAaL2.6 is not homologous to mitochondrial DNA. This implies that these plasmids are all self-replicating. Restriction …

Measurement Of Subcellular Ca2+ Redistribution In Cardiac Muscle In Situ: Time Resolved Rapid Freezing And Electron Probe Microanalysis, Meredith Bond, Mark D. Schluchter, Eva Keller, Christine S. Moravec

Scanning Microscopy

To directly assess the physiological roles of sarcoplasmic reticulum (SR) and miitochondria (MT), we have utilized energy dispersive electron probe microanalysis (EPMA) on ultrathin freeze-dried cryosections from isolated papillary muscles, rapidly frozen at precise time points of the contractile cycle. Using this approach, we can detect redistribution of subcellular Ca²⁺ during the cardiac contractile cycle. Changes in Ca²⁺ of less than 1.0 mmol/kg dry wt can be detected. By determining the variability of the Ca²⁺ measurements in preliminary experiments, we have also demonstrated that it is possible to optimize experimental design, i.e., to predict the number of …

Ultra-High Resolution Scanning Electron Microscopic Studies On The Sarcoplasmic Reticulum And Mitochondria In Various Muscles: A Review, Takuro Ogata, Yuichi Yamasaki

Scanning Microscopy

The three-dimensional structure of the sarcoplasmic reticulum (SR), transverse (T)-axial tubular system and mitochondria in various muscles was examined by means of ultra-high resolution scanning electron microscopy (SEM) after removal of the cytoplasmic matrices and myofilaments by the aldehyde-osmium-DMSO-osmium procedure. The striated muscles reviewed and presented are twitch and slow fibers of the frog, twitch and slow fibers of the chicken, twitch extrafusal fibers and intrafusal fibers of the rat, and cardiac muscle fibers of the rat and dog. In all of these striated muscle fibers, T-tubules run transversely and are coupled with terminal cisternae forming triads or dyads. Sarcotubules …

Scanning Electron Microscopy Of Intracellular Organelles In The Young Odontoblasts Of Rats, Yasutomo Iwai-Liao, Yoshikage Higashi, Masakazu Ishikawa, Hideaki Hori

Scanning Microscopy

Intracellular structures of the odontoblasts were studied by scanning electron microscopy (SEM) using a modified AODO (aldehyde prefixed-osmium-DMSO-osmium) method. Well-developed flattened and layered rER (rough endoplasmic reticulum), paved with its associated ribosomes on its outer surface, were clearly observed in the odontoblast. Branched tubular mitochondria with nodules and swollen endings, interposing between and passing through the fenestrated layered rER, were demonstrated in the functional cells. Oblique and cross-sections of both the rER system and tubular mitochondria showed orthodox configurations similar to those usually described in transmission electron microscopy (TEM) studies. Many finger-like projections constructing the cristae directing towards the inner …

Information And Misinformation Regarding Ischemia Of Heart Muscle Tissue. The Cause Of Cell Death During Blood Reperfusion And Reactivation Of Heart Muscle Tissue After Prolonged Ischemia, Fritiof S. Sjöstrand

Scanning Microscopy

An electron microscopic study of heart muscle tissue exposed to six hours ischemia and prepared according to the low denaturation embedding technique revealed a structural modification confined to the mitochondrial cristae. The modification consisted of a removal of Krebs cycle enzymes from the cristae. Reperfusion of the ischemic tissue after four hours ischemia led to extensive breakdown of the mitochondrial structure and contractility could not be restored. However, when after six hours ischemia the ischemic tissue was reperfused with blood, the composition of which had been modified to stimulate mitochondrial function, no additional structural changes were observed and contractility was …

Functional And Morphological Studies Of Mitochondria Exposed To Undecagold Clusters: Biologic Surfaces Labeling With Gold Clusters, E. Valdivia, C. Gabel, J. E. Reardon, C. A. Cajacob, H. Yang, R. S. Wehbi, G. L. Scott, P. A. Frey, L. A. Fahien

Scanning Microscopy

This study reports morphological and functional alterations observed in respiring isolated mitochondria when they are exposed to nonpenetrating, positive electrostatically charged synthetic undecagold clusters. Modification of the undecagold clusters positive charges change or prevent the functional effects and the binding to the outside surface of the mitochondria. The mitochondrial functional alterations are dependent on the oxidative phosphorylation capacity of the isolated organelles. The results of these experiments indicate that artificial undecagold may be useful to explore the molecular mechanisms of biological energy transducers which require electric charges separation, ionic fluxes, and electric surface properties.

An Analysis Of The Ph Tolerance And Substrate Preference Of Isolated Skeletal Muscle Mitochondria From Bufo Marinus And Rana Catesbeiana, Jeffrey Mark Duerr

Dissertations and Theses

The concept of maximal oxygen consumption (VO₂ max) implies that there is a limit to the amount of oxygen that can be consumed by an organism in a given time. Many attempts have been made to delineate exactly what factor or factors are limiting to VO₂ max. Current models focus on the steps over which oxygen must traverse in order to get from the ambient air to the mitochondria. However, no model has addressed the issue of whether or not carbon dioxide flux may impose a limit to VO₂ max. Impedance of carbon dioxide flux may have …

Intracellular Water Distribution And Aging As Examined By X-Ray Microanalysis, Thomas Von Zglinicki

Scanning Microscopy

The results reviewed here demonstrate that 1. the distribution of dry mass as observed in frozen-dried cryosections might be used as an unbiased measure of intracellular dry mass resp. water distributions in the tissue in vivo and 2. the well-known loss of water from cells during aging is solely due to a water loss from mitochondria without changes in the water content of all other components of the cell in the case of rat liver and heart muscle.

The reason for the water loss might be increased counter ion binding by membrane-bound enzymes due to decreased fluidity of the inner …