DOCSLIB.ORG

Characterization of the Desiccation Tolerance and Potential for Fomite Spread of Streptococcus Pneumoniae

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

Characterization of the Desiccation Tolerance and Potential for Fomite Spread of Streptococcus pneumoniae A thesis submitted by Rebecca L. Walsh In partial fulfillment of the requirements for the degree of Doctor of Philosophy in Molecular Microbiology TUFTS UNIVERSITY Sackler School of Graduate Biomedical Sciences February, 2015 Adviser: Andrew Camilli ABSTRACT Streptococcus pneumoniae is the causative agent of diseases such as otitis media, pneumonia, and bacterial meningitis. Historically, published literature asserted that pneumococcal transmission occurs via direct contact with respiratory secretions from infected individuals, yet spread of other respiratory tract pathogens has been linked to fomites. As the only known reservoir of S. pneumoniae is the human upper respiratory tract, little work has investigated its capacity to survive in the environment. Environmental persistence often depends on an ability to withstand desiccation. A knowledge gap exists regarding the viability of vegetative cells, particularly those of major human pathogens, post dehydration. In an era where nosocomial infections are increasingly common, this has become an important area of study. The goal of this work is to characterize the ability of S. pneumoniae to withstand desiccation. We hypothesize that fomites serve as an alternate source of pneumococcal transmission. To test our hypothesis, we ask three central questions. Can S. pneumoniae survive desiccation? Is S. pneumoniae infectious after desiccation? And which genes or pathways are involved in desiccation tolerance? Here, we describe the development of a desiccation protocol using plate-grown S. pneumoniae. We show that pneumococci can survive at least 28 days of desiccation under ambient conditions, survival is independent of polysaccharide capsule, and desiccation is a more complicated phenomenon than starvation alone. Multiple serotypes survive desiccation, suggesting that this is a species-wide ability encoded by the core pneumococcal genome. Finally, S. pneumoniae retains infectivity in a mouse model of colonization, lending support to the fomite transmission hypothesis. ii To explore the pathways correlated with desiccation tolerance, we constructed a transposon insertion library, which was desiccated for two and four days, after which we performed the Tn-seq method, a high throughput sequencing and quantitation of the transposon junctions. By comparing the frequency of reads for each insertion in the pre- and post-desiccation samples, we determined the importance of each gene for S. pneumoniae’s desiccation survival. Of 12 genes selected for further study, mutants in genes encoding the UvrABC nucleotide excision repair complex, SpxB (pyruvate oxidase), SodA (superoxide dismutase), MscS (mechanosensitive channel of small conductance), and cardiolipin synthase all display phenotypes in stress assays. We demonstrate that S. pneumoniae’s desiccation tolerance is tied to its ability to withstand stresses, including those imposed by osmotic changes and reactive oxygen species, leading to a need for DNA damage repair. iii ACKNOWLEDGEMENTS I must begin by thanking my advisor, Andrew Camilli, who has been my mentor throughout this challenging, and also very rewarding, journey. He has at times been my teacher, my taskmaster, and my biggest champion. Without his insight, enthusiasm, understanding, and encouragement, I would not be at this point. His love for science is contagious, and a constant reminder to me to be passionate about my own work. He also recognizes the importance of perspective, and is very supportive of and interested in lab members’ non-scientific pursuits. Andy, you have made your lab a wonderful place for my graduate career. My graduate work has been improved significantly with input from my committee members Ralph Isberg, Carol Kumamoto, and Joan Mecsas. Thank you for your critical evaluations, your helpful suggestions, and your encouragement along the way. On a daily basis, the Camilli lab members inspired and supported me. In small group discussions, lab meetings, and practice talks, I always received valuable feedback and reassurances. Thank you to all the other S. pneumoniae researchers for your help (and sometimes your samples) – Tim van Opijnen, Katie Price, Revati Masilamani, Mara Shainheit, Chelsea Witte, Neil Greene, Ankur Dalia, and Ellie Fleming. Thank you to my various small group members – Ayman Ismail, Bharathi Patimalla, Kim Seed, Mimi Yen, Heather Kamp, Chelsea, Revati, and Ellie. Thank you to Dave Lazinksi for your suggestions and your crazy bank of knowledge. Thank you to Bharathi for your tireless help with the many mouse experiments. Thank you to lab managers Marc Kimball and Trish Winterfield for being ordering and organizing whizzes. Thank you to past and present members of the Lion Bay – Evan Bradley, Revati, Chelsea, and Mimi – for iv making our end of the lab a blast, whether with musical sing-alongs, Disney paraphernalia, venting sessions, or anything to do with our mascot Sir Percival Riggle. The members of the Molecular Microbiology Program and Department of Molecular Biology and Microbiology are outstanding; thank you to the students, faculty, post-docs, and staff for making it such a collaborative, nurturing, and fun environment. I also need to thank my classmates – Andrew Hempstead, Julia (Murphy) Keith, and Jessica Silverman. From studying together first year, to commiserating about research woes, to wrapping up our graduate work, I couldn’t imagine a better group for me to have experienced all of this with. To my close friends that I’ve made during my time here – Dana, Katie, Marc, Revati, EmilyKate, Stephanie, Julia, Erin, and Mimi – thank you for all of the great memories. Thank you to Greg Priebe for being a wonderful mentor in my years after college, and for pushing me to go after this. Thanks to friends, near and far, for being so positive and understanding – Shaunagh, Penny, Laura and Tom, Marc and Amy, and many more. Finally, and most importantly, thank you to my family who have been unwavering in their belief in me. Jill and Paul, thank you for your reminders that I would get through this. Special thanks to Bobbie, who would have been so excited for me. Mom and Dad, thank you for everything; there are no words. My parents instilled a love of learning and science in all of us, and have been my biggest cheerleaders in everything I do. Lisa and Michael, thank you for your emails, texts, and conversations (scientific and otherwise) that have helped me through this. Gavin, it’s been a long road, and your perspective, confidence, patience, and encouragement continue to amaze me. Thank you for your love and your support. v TABLE OF CONTENTS Abstract ........................................................................................................................... ii Acknowledgements ....................................................................................................... iv Table of Contents .......................................................................................................... vi List of Tables ................................................................................................................. ix List of Figures ..................................................................................................................x List of Abbreviations ................................................................................................... xii CHAPTER 1: Introduction ...........................................................................................1 1.1 Streptococcus pneumoniae ...............................................................................2 1.1.1 Capsule and disease .....................................................................................5 1.1.2 Cell membrane and cardiolipin ....................................................................7 1.2 Bacterial transmission via fomites ..................................................................8 1.3 Desiccation tolerance .....................................................................................13 1.3.1 Desiccation-tolerant bacteria .....................................................................13 1.3.2 Effect of relative humidity .........................................................................14 1.3.3 Effect of season ..........................................................................................17 1.3.4 Effect of cell density ..................................................................................18 1.3.5 Preventative responses to desiccation ........................................................18 1.3.6 Genes identified with roles in desiccation tolerance ..................................20 1.4 Stress response ...............................................................................................23 1.4.1 Oxidative stress response ...........................................................................25 1.4.2 DNA damage repair ...................................................................................28 1.4.3 Competence ................................................................................................31 1.4.4 Protein protection .......................................................................................32 1.4.5 Osmotic stress response .............................................................................33 1.5 Pneumococcal desiccation tolerance ............................................................36
Recommended publications
  • The Rcs Phosphorelay May Regulate the E. Coli Capsule Response to Sublethal Streptomycin Treatment

    The Rcs Phosphorelay May Regulate the E. Coli Capsule Response to Sublethal Streptomycin Treatment

    Journal of Experimental Microbiology and Immunology (JEMI) Copyright © April 2015, M&I UBC The Rcs Phosphorelay May Regulate the E. coli Capsule Response to Sublethal Streptomycin Treatment Iris Luo, Josh Wiebe, Yunan Liu Department of Microbiology and Immunology, University of British Columbia The Escherichia coli colanic acid capsule produced by the cps gene confers resistance in the presence of sublethal antibiotic concentrations. However, the exact mechanism of capsule gene regulation in reaction to the presence of antibiotics is unknown. The two main proposed cps regulation pathways both involve the Rcs phosphorelay system, but differ regarding dependence on RpoS for cps transcription. In this study, we explored the changes in capsule formation and antibiotic resistance in response to treatment with sublethal concentrations of streptomycin using deletion mutants of the two proposed regulation pathways. Wild type, Δ rcsB, Δ rpoS, and Δ cps. E. coli strains were incubated in sublethal concentrations of streptomycin. When examined with MIC assays, the deletion mutants showed higher levels of antibiotic resistance compared to wild type strains of E. coli. We also demonstrated that capsule production was induced under sublethal streptomycin conditions with Maneval staining. Furthermore, qPCR detection of cps transcription indicated downregulation in Δ rcsB strains and upregulation in Δ rpoS after streptomycin treatment. Together, these results suggest that E. coli streptomycin resistance is not dependent on capsule production, and that rcsB and rpoS may both play a role in cps regulation when treated with sublethal doses of streptomycin. Escherichia coli are rod shaped bacteria capable of producing a polysaccharide capsule. The capsule is important for protection from desiccation, survival during oxidative stress, bacterial virulence, and antibiotic resistance (1).
  • Desiccation Tolerance and Drought Acclimation in the Antarctic Collembolan Cryptopygus Antarcticus

    Desiccation Tolerance and Drought Acclimation in the Antarctic Collembolan Cryptopygus Antarcticus

    Journal of Insect Physiology 54 (2008) 1432–1439 Contents lists available at ScienceDirect Journal of Insect Physiology journal homepage: www.elsevier.com/locate/jinsphys Desiccation tolerance and drought acclimation in the Antarctic collembolan Cryptopygus antarcticus Michael A. Elnitsky a,b,*, Joshua B. Benoit c, David L. Denlinger c, Richard E. Lee Jr.a a Department of Zoology, Miami University, Oxford, OH 45056, United States b Department of Biology, Mercyhurst College, Erie, PA 16546, United States c Department of Entomology, The Ohio State University, Columbus, OH 43210, United States ARTICLE INFO ABSTRACT Article history: The availability of water is recognized as the most important determinant of the distribution and Received 9 June 2008 activity of terrestrial organisms within the maritime Antarctic. Within this environment, arthropods Received in revised form 30 July 2008 may be challenged by drought stress during both the austral summer, due to increased temperature, Accepted 4 August 2008 wind, insolation, and extended periods of reduced precipitation, and the winter, as a result of vapor pressure gradients between the surrounding icy environment and the body fluids. The purpose of the Keywords: present study was to assess the desiccation tolerance of the Antarctic springtail, Cryptopygus Desiccation antarcticus, under ecologically-relevant conditions characteristic of both summer and winter along the Drought acclimation Collembola Antarctic Peninsula. In addition, this study examined the physiological changes and effects of mild Cold-hardiness drought acclimation on the subsequent desiccation tolerance of C. antarcticus.Thecollembolans À1 Cryoprotective dehydration possessed little resistance to water loss under dry air, as the rate of water loss was >20% h at 0% relative humidity (RH) and 4 8C.
  • The Evolution of Freeze Tolerance in a Historically Tropical Snail Alice B

    The Evolution of Freeze Tolerance in a Historically Tropical Snail Alice B

    Louisiana State University LSU Digital Commons LSU Doctoral Dissertations Graduate School 2010 The evolution of freeze tolerance in a historically tropical snail Alice B. Dennis Louisiana State University and Agricultural and Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_dissertations Recommended Citation Dennis, Alice B., "The ve olution of freeze tolerance in a historically tropical snail" (2010). LSU Doctoral Dissertations. 1003. https://digitalcommons.lsu.edu/gradschool_dissertations/1003 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Doctoral Dissertations by an authorized graduate school editor of LSU Digital Commons. For more information, please [email protected]. THE EVOLUTION OF FREEZE TOLERANCE IN A HISTORICALLY TROPICAL SNAIL A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in The Department of Biological Sciences by Alice B. Dennis B.S., University of California, Davis 2003 May, 2010 ACKNOWLEDGEMENTS There are many people who have helped make this dissertation possible. I would first like to thank my advisor, Michael E. Hellberg, for his support and guidance. Comments and discussion with my committee: Drs. Sibel Bargu Ates, Robb T. Brumfield, Kenneth M. Brown, and William B. Stickle, have been very helpful throughout the development of this project. I would also like to thank those whose guidance helped lead me down this path, particularly Rick Grosberg, John P. Wares and Alex C. C. Wilson.
  • Advances in Understanding of Desiccation Tolerance of Lichens and Lichen-Forming Algae

    Advances in Understanding of Desiccation Tolerance of Lichens and Lichen-Forming Algae

    plants Review Advances in Understanding of Desiccation Tolerance of Lichens and Lichen-Forming Algae Francisco Gasulla *, Eva M del Campo, Leonardo M. Casano and Alfredo Guéra * Department of Life Sciences, Universidad de Alcalá, Alcalá de Henares, 28802 Madrid, Spain; [email protected] (E.M.d.C.); [email protected] (L.M.C.) * Correspondence: [email protected] (F.G.); [email protected] (A.G.) Abstract: Lichens are symbiotic associations (holobionts) established between fungi (mycobionts) and certain groups of cyanobacteria or unicellular green algae (photobionts). This symbiotic association has been essential in the colonization of terrestrial dry habitats. Lichens possess key mechanisms involved in desiccation tolerance (DT) that are constitutively present such as high amounts of polyols, LEA proteins, HSPs, a powerful antioxidant system, thylakoidal oligogalactolipids, etc. This strategy allows them to be always ready to survive drastic changes in their water content. However, several studies indicate that at least some protective mechanisms require a minimal time to be induced, such as the induction of the antioxidant system, the activation of non-photochemical quenching including the de-epoxidation of violaxanthin to zeaxanthin, lipid membrane remodeling, changes in the proportions of polyols, ultrastructural changes, marked polysaccharide remodeling of the cell wall, etc. Although DT in lichens is achieved mainly through constitutive mechanisms, the induction of protection mechanisms might allow them to face desiccation stress in a better condition. The proportion and relevance of constitutive and inducible DT mechanisms seem to be related to the ecology at which lichens are adapted to. Citation: Gasulla, F.; del Campo, E.M; Casano, L.M.; Guéra, A.
  • Desiccation Tolerance of Adult Stem Cells in the Presence of Trehalose and Glycerol

    Desiccation Tolerance of Adult Stem Cells in the Presence of Trehalose and Glycerol

    The Open Biotechnology Journal, 2008, 2, 211-218 211 Open Access Desiccation Tolerance of Adult Stem Cells in the Presence of Trehalose and Glycerol Surbhi Mittal and Ram V. Devireddy* Bioengineering Laboratory, Department of Mechanical Engineering, Louisiana State University, Baton Rouge, LA, USA Abstract: Development of protocols for storing desiccated cells at ambient temperatures offers tremendous economic and practical advantages over traditional storage procedures like cryopreservation and freeze-drying. As a first step for devel- oping such procedures for adult stem cells, we have measured the post-rehydration membrane integrity (PRMI) of two passages, Passage-0 (P0) and Passage-1 (P1), of human adipose-derived stem cells (ASCs). ASCs were dried using a con- vective stage at three different drying rates (slow, moderate and rapid) in D-PBS with trehalose (50 mM) and glycerol (384 mM). ASCs were incubated in the drying media for 30 mins prior to drying at the prescribed rate on the convective stage for 30 mins. After drying, the ASCs were stored for 48 hrs in three different conditions: i) at ambient temperature, ii) in plastic bags at ambient temperature and iii) in vacuum sealed plastic bags at ambient temperature. PRMI was as- sessed after incubating the rehydrated ASCs with stromal medium for a further 48 hrs. Our measurements show that the PRMI of ASCs was: i) higher when ASCs were dried slowly; ii) increased when they were stored in vacuum as opposed to at ambient or in plastic bags; and iii) decreased with increasing passage of ASCs, i.e. under similar drying and storage conditions P0 ASCs had higher PRMI than P1 ASCs.
  • Bacillus Subtilis

    Bacillus Subtilis

    Das Phagenschock-Protein LiaH aus Bacillus subtilis Dissertation der Fakultät für Biologie der Ludwig-Maximilians-Universität München Vorgelegt von aus Leisnig München April 2012 1. Gutachter: Prof. Dr. Thorsten Mascher 2. Gutachterin: Prof. Dr. Ute Vothknecht Tag der Abgabe: 10.04.2012 Tag der mündlichen Prüfung: 31.10.2012 Eidesstattliche Versicherung und Erklärung Hiermit versichere ich an Eides statt, dass die vorliegende Dissertation von mir selbständig und ohne unerlaubte Hilfe angefertigt wurde. Zudem wurden keine anderen als die angegebenen Quellen verwendet. Außerdem versichere ich, dass die Dissertation keiner anderen Prüfungskommission vorgelegt wurde und ich mich nicht anderweitig einer Doktorprüfung ohne Erfolg unterzogen habe. München, den 10.04.2012 ____________________________ Diana Wolf „Nichts beflügelt die Wissenschaft so, wie der Schwatz mit Kollegen auf dem Flur.“ Arno Penzias (*1933), amerik. Physiker, 1978 Nobelpreis Inhaltsverzeichnis Inhaltsverzeichnis Publikationsliste IV Abkürzungsverzeichnis V Zusammenfassung VII Summary IX Kapitel I: Einleitung 1 I.1. Aufbau der bakteriellen Zellwand 1 I.2. Zellwandbiosynthese 2 I.3. Die Zellwand als Ziel von antibiotisch wirkenden Substanzen 5 I.4. Die Zellhüllstressantwort in Gram-positiven Bakterien am Beispiel B. subtilis 8 I.5. Das LiaFSR-Dreikomponentensystem in B. subtilis 11 I.5.1. Induktion des LiaFSR-3KS 12 I.5.2. Regulation und Funktion des LiaFSR-3KS 12 I.6. Die Zellhüllstressantwort in Gram-negativen Bakterien am Beispiel E. coli 14 I.7. Die Phagenschock-Antwort in E. coli 16 I.7.1. Induktion der Phagenschock-Antwort 17 I.7.2. Regulation der Phagenschock-Antwort 18 I.7.3. Rolle der Phagenschock-Antwort im Energiestoffwechsel 20 I.8. Die Phagenschock-Antwort in anderen Organismen 20 I.8.1.
  • Metabolic Shift from Glycogen to Trehalose Promotes Lifespan

    Metabolic Shift from Glycogen to Trehalose Promotes Lifespan

    Metabolic shift from glycogen to trehalose promotes PNAS PLUS lifespan and healthspan in Caenorhabditis elegans Yonghak Seoa, Samuel Kingsleya, Griffin Walkera, Michelle A. Mondouxb, and Heidi A. Tissenbauma,c,1 aDepartment of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School (UMMS), Worcester, MA 01605; bDepartment of Biology, College of the Holy Cross, Worcester, MA 01610; and cProgram in Molecular Medicine, UMMS, Worcester, MA 01605 Edited by Gary Ruvkun, Massachusetts General Hospital, Boston, MA, and approved February 13, 2018 (received for review August 10, 2017) As Western diets continue to include an ever-increasing amount of dition of trehalose to the standard E. coli diet promotes longevity sugar, there has been a rise in obesity and type 2 diabetes. To avoid (27) in contrast to the toxicity caused by the addition of glucose metabolic diseases, the body must maintain proper metabolism, even (5–8). Furthermore, mutants have been identified that are long on a high-sugar diet. In both humans and Caenorhabditis elegans, lived and store increased trehalose (27). Therefore, an association excess sugar (glucose) is stored as glycogen. Here, we find that ani- between longevity and trehalose has been established. Mammals do mals increased stored glycogen as they aged, whereas even young not store sugar as trehalose but do possess the enzyme trehalase to adult animals had increased stored glycogen on a high-sugar diet. breakdown ingested trehalose (28). Further, oral supplementation Decreasing the amount of glycogen storage by modulating the C. of trehalose has been shown to improve glucose tolerance in in- elegans glycogen synthase, gsy-1, a key enzyme in glycogen synthe- dividuals at high risk for developing type 2 diabetes (29) and can sis, can extend lifespan, prolong healthspan, and limit the detrimental improve recovery from traumatic brain injury in mice (30).
  • Geographic Variation in Adult and Embryonic Desiccation Tolerance In

    Geographic Variation in Adult and Embryonic Desiccation Tolerance In

    bioRxiv preprint doi: https://doi.org/10.1101/314351; this version posted October 21, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. Geographic variation in adult and embryonic desiccation tolerance in a terrestrial-breeding frog Rudin-Bitterli, T.S.1,2 *, Evans, J.P.1,2 & Mitchell, N.J.1 1 - School of Biological Sciences, The University of Western Australia, Crawley, Western Australia 6009, Australia 2 - Centre for Evolutionary Biology, The University of Western Australia, Crawley, Western Australia 6009, Australia Keywords: amphibians, desiccation tolerance, intra-specific variation, climate change, adaptation, phenotypic plasticity, environmental sensitivity 1 bioRxiv preprint doi: https://doi.org/10.1101/314351; this version posted October 21, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. ABSTRACT Intra-specific variation in the ability of individuals to tolerate environmental perturbations is often neglected when considering the impacts of climate change. Yet this information is potentially crucial for mitigating any deleterious effects of climate change on threatened species. Here we assessed patterns of intra-specific variation in desiccation tolerance in the frog Pseudophryne guentheri, a terrestrial-breeding species experiencing a drying climate. Adult frogs were collected from six populations across a rainfall gradient and their dehydration and rehydration rates were assessed.
  • Membrane and Lipid Metabolism Plays an Important Role in Desiccation Resistance in the Yeast Saccharomyces Cerevisiae

    Membrane and Lipid Metabolism Plays an Important Role in Desiccation Resistance in the Yeast Saccharomyces Cerevisiae

    Membrane and lipid metabolism plays an important role in desiccation resistance in the yeast Saccharomyces cerevisiae Qun Ren University of Wyoming Rebecca Brenner University of Wyoming Thomas C. Boothby University of Wyoming Zhaojie Zhang ( [email protected] ) University of Wyoming https://orcid.org/0000-0001-6790-6243 Research article Keywords: anhydrobiosis, desiccation tolerance, endoplasmic reticulum, lipid droplets, lipid metabolism, mitochondria, vacuole Posted Date: October 27th, 2020 DOI: https://doi.org/10.21203/rs.3.rs-48916/v3 License: This work is licensed under a Creative Commons Attribution 4.0 International License. Read Full License Version of Record: A version of this preprint was published on November 10th, 2020. See the published version at https://doi.org/10.1186/s12866-020-02025-w. Page 1/23 Abstract Background Anhydrobiotes, such as the yeast Saccharomyces cerevisiae, are capable of surviving almost total loss of water. Desiccation tolerance requires an interplay of multiple events, including preserving the protein function and membrane integrity, preventing and mitigating oxidative stress, maintaining certain level of energy required for cellular activities in the desiccated state. Many of these crucial processes can be controlled and modulated at the level of organelle morphology and dynamics. However, little is understood about what organelle perturbations manifest in desiccation-sensitive cells as a consequence of drying or how this differs from organelle biology in desiccation-tolerant organisms undergoing anhydrobiosis. Results In this study, electron and optical microscopy was used to examine the dynamic changes of yeast cells during the desiccation process. Dramatic structural changes were observed during the desiccation process, including the diminishing of vacuoles, decrease of lipid droplets, decrease in mitochondrial cristae and increase of ER membrane, which is likely caused by ER stress and unfolded protein response.
  • Cuticular Lipid Mass and Desiccation Rates in Glossina Pallidipes: Interpopulation Variation Russell A

    Cuticular Lipid Mass and Desiccation Rates in Glossina Pallidipes: Interpopulation Variation Russell A

    Entomology Publications Entomology 2007 Cuticular lipid mass and desiccation rates in Glossina pallidipes: interpopulation variation Russell A. Jurenka Iowa State University, [email protected] John S. Terblanche Stellenbosch University C. Jaco Klok Stellenbosch University Steven L. Chown Stellenbosch University Elliot S. Krafsur Iowa State University Follow this and additional works at: http://lib.dr.iastate.edu/ent_pubs Part of the Biochemistry Commons, Entomology Commons, Genetics Commons, and the Structural Biology Commons The ompc lete bibliographic information for this item can be found at http://lib.dr.iastate.edu/ ent_pubs/276. For information on how to cite this item, please visit http://lib.dr.iastate.edu/ howtocite.html. This Article is brought to you for free and open access by the Entomology at Iowa State University Digital Repository. It has been accepted for inclusion in Entomology Publications by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Cuticular lipid mass and desiccation rates in Glossina pallidipes: interpopulation variation Abstract Tsetse flies, Glossina pallidipes (Diptera: Glossinidae) are said to have strong dispersal tendencies. Gene flow among these populations is estimated to be the theoretical equivalent of no more than one or two reproducing flies per generation, thereby raising the hypothesis of local regimes of natural selection. Flies were sampled from four environmentally diverse locations in Kenya to determine whether populations are homogeneous in desiccation tolerance and cuticular lipids. Cuticular hydrocarbon fractions known to act as sex pheromones do not differ among populations, thereby eliminating sexual selection as an isolating mechanism. Cuticular lipid quantities vary among populations and are not correlated with prevailing temperatures, humidities, and normalized density vegetation indices.
  • Effects of Starvation and Desiccation on Energy Metabolism in Desert and Mesic Drosophila M.T

    Effects of Starvation and Desiccation on Energy Metabolism in Desert and Mesic Drosophila M.T

    Journal of Insect Physiology 49 (2003) 261–270 www.elsevier.com/locate/jinsphys Effects of starvation and desiccation on energy metabolism in desert and mesic Drosophila M.T. Marron a,1, T.A. Markow b, K.J. Kain a,2, A.G. Gibbs a,∗ a Department of Ecology and Evolutionary Biology, University of Arizona, 1041 E. Lowell St., Tucson, AZ 85721, USA b Center for Insect Science, University of Arizona, 1037 E. Lowell St., Tucson, AZ 85721, USA Received 23 July 2002; received in revised form 11 December 2002; accepted 11 December 2002 Abstract Energy availability can limit the ability of organisms to survive under stressful conditions. In Drosophila, laboratory experiments have revealed that energy storage patterns differ between populations selected for desiccation and starvation. This suggests that flies may use different sources of energy when exposed to these stresses, but the actual substrates used have not been examined. We measured lipid, carbohydrate, and protein content in 16 Drosophila species from arid and mesic habitats. In five species, we measured the rate at which each substrate was metabolized under starvation or desiccation stress. Rates of lipid and protein metab- olism were similar during starvation and desiccation, but carbohydrate metabolism was several-fold higher during desiccation. Thus, total energy consumption was lower in starved flies than desiccated ones. Cactophilic Drosophila did not have greater initial amounts of reserves than mesic species, but may have lower metabolic rates that contribute to stress resistance. 2003 Elsevier Science Ltd. All rights reserved. Keywords: Carbohydrate; Desiccation; Drosophila; Energetics; Lipid; Metabolic rate; Starvation; Stress resistance 1.
  • The Reduction of T7 Phage Adsorption in Escherichia Coli B23 Cells Treated with Sub-Lethal Levels of Kanamycin

    The Reduction of T7 Phage Adsorption in Escherichia Coli B23 Cells Treated with Sub-Lethal Levels of Kanamycin

    Journal of Experimental Microbiology and Immunology (JEMI) Vol. 13:89-92 Copyright © April 2009, M&I UBC The Reduction of T7 Phage Adsorption in Escherichia coli B23 Cells Treated with Sub-Lethal Levels of Kanamycin Joanne Bleackley, Jesse Cooper, Monica Kaminski and Stephanie Sandilands Department of Microbiology & Immunology, UBC The production of capsular material has been implicated as a bacterial defence mechanism against certain antibiotics and against phage adsorption. The capsule acts to block the phage from binding to its receptor on the bacterial cell which effectively inhibits phage adsorption. Previously, it has been shown that exposing Escherichia coli B23 cells to sub-inhibitory levels of the antibiotic kanamycin results in an increase in extracellular polysaccharide production, possibly in the form of a capsule. In the current study, this phenomenon was investigated using T7 phage adsorption as a model to assess the presence of a capsule. Phage adsorption assays were performed on both E. coli B23 cells treated with sub-lethal levels of kanamycin for 1 hour and untreated cells. T7 phage adsorption was shown to be diminished in E. coli treated with antibiotic, as compared to those which had not been treated with antibiotic. This decrease in phage adsorption to the antibiotic treated cells suggests that the induced extracellular polysaccharide produced by these cells is part of the capsule. Thus, this work provides further insight into the likely nature of the induced-extracellular polysaccharide produced by these cells following antibiotic treatment. Bacteria have developed mechanisms to adapt to phage adsorption (17). Binding of T7 phage to LPS changes in their environment.