DOCSLIB.ORG

A Decade of Imaging Cellular Motility and Interaction Dynamics in the Immune System REVIEW

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
A Decade of Imaging Cellular Motility and Interaction Dynamics in the Immune System REVIEW REVIEW riod have changed concepts of the relationship between tissue organization and the develop- ment of adaptive immunity, provided new in- A Decade of Imaging Cellular sights into how innate immune effectors carry out their search and destroy missions, yielded quanti- tative data that have altered previous models of Motility and Interaction Dynamics adaptive immune response development, and helped provide insight into the effect of gene mu- in the Immune System tations on immunity that could not have been gained by other means. Other studies have re- 1 2 3 Ronald N. Germain, *† Ellen A. Robey, *† Michael D. Cahalan *† vealed in colorful detail how immune cells in- teract with a diverse array of pathogens, the basis To mount an immune response, lymphocytes must recirculate between the blood and lymph for immunoregulation in secondary lymphoid tis- nodes, recognize antigens upon contact with specialized presenting cells, proliferate to expand a sues, and the effects of immunosuppressive drugs small number of clonally relevant lymphocytes, differentiate to antibody-producing plasma cells on immune cell behavior in vivo. In short, in situ or effector T cells, exit from lymph nodes, migrate to tissues, and engage in host-protective imaging has proved a powerful tool to investigate activities. All of these processes involve motility and cellular interactions—events that were the cellular dynamics of the immune response hidden from view until recently. Introduced to immunology by three papers in this journal in 2002, in lymphoid organs and in peripheral tissues in vivo live-cell imaging studies are revealing the behavior of cells mediating adaptive and (Fig. 1). Here, we try to synthesize the key con- innate immunity in diverse tissue environments, providing quantitative measurement of cellular ceptual advances that have come from this re- motility, interactions, and response dynamics. Here, we review themes emerging from such search, not seeking a comprehensive review of Downloaded from studies and speculate on the future of immunoimaging. the literature, but focusing on how the application of this technology has fundamentally changed uring embryonic development of com- nized for half a century (1), and the dynamic our understanding of immune system organiza- plex metazoans, rapid cell division, large- process of leukocyte extravasation from blood tion and physiology. We end with some thoughts scale movement of cells, and inductive to tissue studied using video imaging for nearly about the future. D http://science.sciencemag.org/ interactions result in further differentiation and 20 years (2), it is only in the past decade that specialization. These latter events depend great- multiplex, high-resolution, dynamic, in situ ex- Lymph Node Cellular Dynamics and the ly on cellular location and take account of both amination of this complex choreography of im- Initiation of T Cell Adaptive Immune Responses contact-dependent and soluble signals. But this mune cell motion, interaction, and function has Among the most striking findings to emerge from panoply of highly dynamic processes is largely been possible. Starting with a series of papers dynamic imaging analyses is the seemingly ran- absent from adult organisms, replaced by rela- in 2002, three of which appeared together in dom pattern of robust cellular migration exhib- tively stable tissue architectures and stereotypi- this journal (3–5), our understanding of how cell ited by many cell types under basal conditions cal spatial relocation of terminal cells in epithelial movement, positioning, and interaction contrib- and the efficiency with which cells direct their structures from basal progenitors. Neural net- ute to effective immune responses has undergone attention to particular targets by short- or long- works undergo local modifications and pruning, explosive growth using one- and, more common- range migrations during active immune responses. but wide-scale cell position changes and replace- ly, two-photon (2P) microscopy to visualize liv- T cells are able to crawl more rapidly than any on July 30, 2018 ment are rare. ing cells in vivo and in tissue explant preparations other cell type in the body. Similar amoeboid The cells of the immune system stand out (Box 1). The observations made during this pe- actin-based motility at a somewhat slower pace is against this general landscape in retaining many of the properties of the embryonic state. Aside from the initial seeding of some resident myeloid Liver and lymphoid cells into specific tissues and or- Brain Patrolling by immune cells, Skin gans, there is widespread movement throughout Infection infection Infection, transplantation, life of many cell types from bone marrow to the anti-tumor immunity thymus and secondary lymphoid organs, entry into a variety of tissue sites in response to damage or microbial invasion, extensive signaling through Small bowel transient contacts lasting minutes to hours, transient Dendritic cell trans-epithelial exchange of differentiation-inducing or viability- bacterial sampling sustaining information, and rapid cell division that rivals the rates seen during embryogenesis. Although the existence of circulating and Thymus tissue-invading immune cells has been recog- Bone marrow T cell development Memory T cell dynamics, Lymph nodes bone homeostasis 1Laboratory of Systems Biology, National Institute of Allergy T cell, B cell, dendritic cell dynamics, and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA. 2Department of Molecular and Cell Biology, antigen capture, infection University of California Berkeley, Berkeley, CA 94720, USA. 3Department of Physiology and Biophysics, University of Cal- ifornia Irvine, Irvine, CA 92697, USA. Fig. 1. Two-photon imaging of different anatomical sites in the mouse. Although early 2P studies of the immune system focused on T cell activation in the lymph node, in the past decade this approach has been *All authors contributed equally to this manuscript. †To whom correspondence should be addressed. E-mail: extended to a variety of different tissues, using both intravital imaging approaches and tissue explants. [email protected] (R.N.G.); [email protected] (E.A.R.); Processes that have been examined include immune responses to infection, immune homeostasis, [email protected] (M.D.C.) transplant immunology, antitumor immunology, and regulation of immune responses. 1676 29 JUNE 2012 VOL 336 SCIENCE www.sciencemag.org REVIEW the default status of B lymphocytes (4, 6), natural receptor 1 (S1P1); both G protein–coupled re- they acquire chemokinetic signals enabling more killer cells (7, 8), neutrophils (9, 10), and mono- ceptors ensure directed migration at the global rapid migration (25). These imaging data refined cytes (11). Collectively, these cells can be regarded level into and out of the lymph node (22). The earlier concepts based on static imaging that sug- as the explorers, using cell surface receptors to dynamic nature of lymphocyte movement as re- gested a possible role of the FRC network in sample the environment and responding with vealed by the earliest imaging studies of these guiding intranodal lymphocyte movement (26). altered motility when signals are transmitted. secondary lymphoid organs, first in explants Inflammatory chemokine production by DCs or On the other hand, antigen-presenting cells (4, 12) and then in intravital preparations (13, 23), DC-T cell combinations can also influence the (APCs), such as dendritic cells (DCs) (5, 12–16) demonstrated that lymphocytes actively migrate migration of T cells within the lymph node, lead- and Langerhans cells (17, 18), are generally sessile to pass from their entry sites at high endothelial ing to more directed movement on this network in tissue unless induced to migrate by microbial venules to their exit at efferent lymphatics. The (27, 28). On the APC side of the equation, in- or inflammatory signals (16, 18, 19), actively remarkably rapid pace of T cell movement while dividual resident and migratory DCs extend agile waving their DC processes and displaying on in the dense paracortical region of the node, how- dendrites and contact hundreds or thousands of their surface major histocompatibility complex ever, and the way in which the cells scanned for motile T cells per hour to enable efficient rep- (MHC)–encoded proteins a short-term historical antigen, were nonetheless unexpected. When ertoire scanning (14). Together these observa- record of pathogen invasion. When antigen re- viewed in time lapse, it looks chaotic; in fact, tions suggest that structural and chemical cues ceptors are engaged by antigen or chemokines, naïve T and B cell tracks are well described as a are used to enhance the likelihood that rare cells lymphocytes often stop (5, 12, 13, 20, 21)as random walk (4, 13, 23). When antigen is present, will colocalize and come into contact in the signals begin to transform seemingly random mo- however, T and B cells respond by altering their shortest possible time after antigen entry, driving tility into directed responses that reveal coordi- ongoing random migration, initiating interactions effective adaptive responses. nated cellular behavior, including local swarming that lead to antibody production, proliferation, Intravital imaging has also uncovered a pre- or directed migration from one region to another. differentiation to memory or effector cells, and viously unappreciated sequence of kinetic behav- Local motility can evolve into long-range migra- exit from
Load more

Recommended publications
  • Glossary - Cellbiology
    1 Glossary - Cellbiology Blotting: (Blot Analysis) Widely used biochemical technique for detecting the presence of specific macromolecules (proteins, mRNAs, or DNA sequences) in a mixture. A sample first is separated on an agarose or polyacrylamide gel usually under denaturing conditions; the separated components are transferred (blotting) to a nitrocellulose sheet, which is exposed to a radiolabeled molecule that specifically binds to the macromolecule of interest, and then subjected to autoradiography. Northern B.: mRNAs are detected with a complementary DNA; Southern B.: DNA restriction fragments are detected with complementary nucleotide sequences; Western B.: Proteins are detected by specific antibodies. Cell: The fundamental unit of living organisms. Cells are bounded by a lipid-containing plasma membrane, containing the central nucleus, and the cytoplasm. Cells are generally capable of independent reproduction. More complex cells like Eukaryotes have various compartments (organelles) where special tasks essential for the survival of the cell take place. Cytoplasm: Viscous contents of a cell that are contained within the plasma membrane but, in eukaryotic cells, outside the nucleus. The part of the cytoplasm not contained in any organelle is called the Cytosol. Cytoskeleton: (Gk. ) Three dimensional network of fibrous elements, allowing precisely regulated movements of cell parts, transport organelles, and help to maintain a cell’s shape. • Actin filament: (Microfilaments) Ubiquitous eukaryotic cytoskeletal proteins (one end is attached to the cell-cortex) of two “twisted“ actin monomers; are important in the structural support and movement of cells. Each actin filament (F-actin) consists of two strands of globular subunits (G-Actin) wrapped around each other to form a polarized unit (high ionic cytoplasm lead to the formation of AF, whereas low ion-concentration disassembles AF).
    [Show full text]
  • Marine Microplankton Ecology Reading
    Marine Microplankton Ecology Reading Microbes dominate our planet, especially the Earth’s oceans. The distinguishing feature of microorganisms is their small size, usually defined as less than 200 micrometers (µm); they are all invisible to the naked eye. As a group, sea microbes are extremely diverse, and extremely versatile with respect to their abilities to make and eat food. All marine microbes are too small to swim against the current and are therefore classified as plankton. First we will discuss several ways to classify marine microbes. 1. Size Planktonic marine organisms can be divided into the following size categories: Category Size femtoplankton <0.2 µm picoplankton 0.2-2 µm nanoplankton 2-20 µm microplankton 20-200 µm mesoplankton 200-2000 µm In this laboratory we are concerned with the microscopic portion of the plankton, less than 200 µm. These organisms are not visible to the naked eye (Figure 1). Figure 1. Size classes of marine plankton 2. Type A. Viruses Viruses are the smallest and simplest microplankton. They range from 0.01 to 0.3 um in diameter. Externally, viruses have a capsid, or protein coat. Viruses can also have simple or complex external morphologies with tail fibers and structures that are used to inject DNA or RNA into their host. Viruses have little internal morphology. They do not have a nucleus or organelles. They do not have chlorophyll. Inside a virus there is only nucleic acid, either DNA or RNA. Viruses do not grow and have no metabolism. Marine viruses are highly abundant. There are up to 10 billion in one liter of seawater! B.
    [Show full text]
  • Gastrointestinal Motility Physiology
    GASTROINTESTINAL MOTILITY PHYSIOLOGY JAYA PUNATI, MD DIRECTOR, PEDIATRIC GASTROINTESTINAL, NEUROMUSCULAR AND MOTILITY DISORDERS PROGRAM DIVISION OF PEDIATRIC GASTROENTEROLOGY AND NUTRITION, CHILDREN’S HOSPITAL LOS ANGELES VRINDA BHARDWAJ, MD DIVISION OF PEDIATRIC GASTROENTEROLOGY AND NUTRITION CHILDREN’S HOSPITAL LOS ANGELES EDITED BY: CHRISTINE WAASDORP HURTADO, MD REVIEWED BY: JOSEPH CROFFIE, MD, MPH NASPGHAN PHYSIOLOGY EDUCATION SERIES SERIES EDITORS: CHRISTINE WAASDORP HURTADO, MD, MSCS, FAAP [email protected] DANIEL KAMIN, MD [email protected] CASE STUDY 1 • 14 year old female • With no significant past medical history • Presents with persistent vomiting and 20 lbs weight loss x 3 months • Initially emesis was intermittent, occurred before bedtime or soon there after, 2-3 hrs after a meal • Now occurring immediately or up to 30 minutes after a meal • Emesis consists of undigested food and is nonbloody and nonbilious • Associated with heartburn and chest discomfort 3 CASE STUDY 1 • Initial screening blood work was unremarkable • A trial of acid blockade was started with improvement in heartburn only • Antiemetic therapy with ondansetron showed no improvement • Upper endoscopy on acid blockade was normal 4 CASE STUDY 1 Differential for functional/motility disorders: • Esophageal disorders: – Achalasia – Gastroesophageal Reflux – Other esophageal dysmotility disorders • Gastric disorders: – Gastroparesis – Rumination syndrome – Gastric outlet obstruction : pyloric stricture, pyloric stenosis •
    [Show full text]
  • JMY: Actin up in Cell Motility Migrate Faster in a Wound Healing Assay That Assesses Cell Motility
    RESEARCH HIGHLIGHTS Nature Reviews Molecular Cell Biology | AOP, published online 2 April 2009; doi:10.1038/nrm2678 — the area closest to the direction CYTOSKELETON of movement — in motile cells. This suggests a role for JMY in cell motility. Indeed, cells that overexpress JMY JMY: actin up in cell motility migrate faster in a wound healing assay that assesses cell motility. By contrast, Actin nucleation — the initial step in filaments. A study now identifies the knockdown of JMY decreases the rate the formation of new actin filaments p53 cofactor JMY as a novel actin of wound healing as a result of reduced — can be induced by the actin-related nucleation factor that combines the ...JMY actin nucleation. Significantly, JMY was protein 2/3 (Arp2/3) complex, which nucleating activities of these proteins specifically induced to the cell leading creates branched actin filaments, to promote cell motility. contributes to edge in response to wounding. Thus, and spire, which creates unbranched The authors observed a potential the assembly the activity of JMY as a transcriptional Arp2/3-activating sequence, WWWCA, of the actin cofactor and actin nucleation factor in JMY. WWWCA contains three repeats seems to be regulated by its cellular of the actin monomer-binding domain cytoskeleton localization. WH2, in addition to a domain that can and cell In short, the authors propose that bind actin and Arp2/3. Intriguingly, in motility... JMY contributes to the assembly of the vitro, JMY can both activate Arp2/3 and, actin cytoskeleton and cell motility by in the absence of Arp2/3, induce rapid first nucleating new filaments, using actin polymerization.
    [Show full text]
  • The Effect of Azide on Phototaxis in Chlamydomonas Reinhardi (Motility)
    Proc. Nat. Acad. Sci. USA Vol. 71, No. 5, pp. 1824-1827, May 1974 The Effect of Azide on Phototaxis in Chlamydomonas reinhardi (motility) ROBERT L. STAVIS Department of Molecular Biology, Division of Biological Sciences, Albert Einstein College of Medicine, Bronx, New York 10461 Communicated by Alfred Gilman, February 25, 1974 ABSTRACT Phototaxis in Chlamydomonas reinhardi section of a cuvette. The maximum rate of accumulation was specifically inhibited by azide. The effect of azide was divided by the concentration of cells rapid and reversible, and did not depend upon the intensity .(AOD8wo/min) (ODwo) of actinic light. Under conditions of completely inhibited is the phototaxis coefficient, a measure of phototaxis indepen- phototaxis, azide had no effect on the number of motile dent of cell density. The actinic light used in these studies was cells in the population or on the rate of motility. The an Osram 150-W xenon lamp in an Oriel 6137 lamp housing effect was not related to changes in oxygen uptake or (Oriel Corp. of America, Stamford, Conn.). Light below 350 cellular ATP concentration. Apparently, a cellular com- ponent or process specifically involved in phototaxis is nm or above 650 nm was excluded by filtering the light source inactivated by azide. with an Oriel C-722-3900 long-pass filter, a G-774-4450 band-pass filter, and a G-776-7100 infrared-absorbing filter. The stimulus-response system that mediates the tactic be- The resulting light had a maximum intensity at 445 nm, with havior of microorganisms may be thought of as consisting a half-maximum band width of about 100 nm and an intensity of components that function as stimulus receptor, a transmis- of about 100 J/m2 per see at the phototaxis cuvette.
    [Show full text]
  • Actin-Based Motility of Pathogenic Bacteria
    Journal of Cell Science 112, 1697-1708 (1999) 1697 Printed in Great Britain © The Company of Biologists Limited 1999 JCS9942 A comparative study of the actin-based motilities of the pathogenic bacteria Listeria monocytogenes, Shigella flexneri and Rickettsia conorii E. Gouin1, H. Gantelet1, C. Egile2, I. Lasa1,*, H. Ohayon3, V. Villiers1, P. Gounon3, P. J. Sansonetti2 and P. Cossart1,‡ 1Unité des Interactions Bactéries-Cellules, 2Unité de Pathogénie Microbienne Moléculaire, 3Station Centrale de Microscopie Electronique, Institut Pasteur, 25 and 28 Rue du Dr Roux, 75724 Paris Cedex 15, France *Present address: Dpto. Producción agraria, Universidad Pública de Navarra, Campus de Arrosadia s/n, Pamplona-31006, Spain ‡Author for correspondence (e-mail: [email protected]) Accepted 17 March; published on WWW 11 May 1999 SUMMARY Listeria monocytogenes, Shigella flexneri, and Rickettsia of actin with the S1 subfragment of myosin in infected cells conorii are three bacterial pathogens that are able to showed that the comet tails of Rickettsia have a structure polymerize actin into ‘comet tail’ structures and move strikingly different from those of L. monocytogenes or S. within the cytosol of infected cells. The actin-based flexneri. In Listeria and Shigella tails, actin filaments form motilities of L. monocytogenes and S. flexneri are known to a branching network while Rickettsia tails display longer require the bacterial proteins ActA and IcsA, respectively, and not cross-linked actin filaments. Immunofluorescence and several mammalian cytoskeleton proteins including studies revealed that the two host proteins, VASP and α- the Arp2/3 complex and VASP (vasodilator-stimulated actinin colocalized with actin in the tails of Rickettsia but phosphoprotein) for L.
    [Show full text]
  • Microbial Motility in 3-D Extending the Reach of Phase Contrast Microscopy to Track the Three- Dimensional Motility of Microbes from Woods Hole, MA
    Microbial Motility in 3-D Extending the reach of phase contrast microscopy to track the three- dimensional motility of microbes from Woods Hole, MA. Max Villa, Microbial Diversity 2016, Marine Biological Lab, Woods Hole, MA, Home Institution: Duke University, Durham, NC Abstract Bacteria solve complex 3D optimization problems to search for energy sources in oligotrophic environments. However, until now, accessing their 3D motility patterns has been limited to expensive and complex microscopy systems. Herein, a recent algorithm that using the diffraction patterns of out-of-focus bacteria to determine their Z-location is implemented and applied to a diverse collection of marine bacteria isolated from around Woods Hole, MA. Introduction We fundamentally rely on the concept of search. Google, Yahoo, Baidu and others have made search a modern necessity and changed our vernacular (“you can google it”). Microbial chemo- and phototaxis (“search”) in oligotrophic marine environments is essential to survival and to our understanding of how microbes influence the ecology of their environment. Patterns of microbial motility can help us better understand how bacteria sense and respond to chemical cues in their microenvironment.1,2, 3 Studying motility in the context of populations can provide insights into variations in their behavior across the population, so-called ‘bacterial individuality’.4,5 Finally, few models exist to quantitatively connect genetics to behavior. 6 High throughput tracking of bacteria is an ideal system for efficiently producing large datasets to probe the connection between behavior and genetics. A deep understanding of diverse microbial motility should lead to more predictive models of how microbes shape our environment.
    [Show full text]
  • Molecular Marine Microbiology
    J. Molec. Microbiol. Biotechnol. (1999) 1(1): 3-4. JMMBMarine Symposium Microbiology 3 Molecular Marine Microbiology Douglas H. Bartlett* describes the bacterial manufacturing of magnetic iron containing organelles (magnetosomes) within certain Center for Marine Biotechnology and Biomedicine benthic bacteria and their biotechnological promise in Scripps Institution of Oceanography products ranging from magnetic tapes to magnetic University of California, San Diego resonance imaging devices. La Jolla, CA 92093-0202, USA Two articles deal with mysterious motility mechanisms operating in marine microbes. Linda McCarter introduces surface-regulated phenomena, including swarming motility The following thirteen minireviews introduce some of the via lateral flagella, in the human pathogen and marine exciting milestones being covered in molecular marine resident, V. parahaemolyticus. Bianca Brahamsha details microbiology today, and in many cases, their biomedical the only known case of liquid motility in the absence of or biotechnological relevance. The issues covered include flagella, a phenotype displayed by many marine quorum and anti-quorum sensing, selected symbioses, Synechococcus species. DNA shuffling in the environment, the evolution and devel- The minireviews end with descriptions of the opment of novel motility mechanisms, hydrocarbon deg- adaptations of certain deep-sea prokaryotes to extremes radation, the interactions of microbes with metals, and of pressure and temperature. Kato and Qureshi present a adaptations to extremes of pressure and temperature. Al- taxomonic overview of deep-sea bacteria and genetic and though most of these topics are not exclusive to marine biophysical analyses of respiratory chain adaptations to realms, they all have as a common thread a profound rel- elevated pressure. My article describes genetic evidence evance to the ocean environment.
    [Show full text]
  • Normal Gastrointestinal Motility and Function Esophagus
    Normal Gastrointestinal Motility and Function "Motility" is an unfamiliar word to many people; it is used primarily to describe the contraction of the muscles in the gastrointestinal tract. Because the gastrointestinal tract is a circular tube, when these muscles contract, they close off the tube or make the opening inside smaller - they squeeze. These muscles can contract in a synchronized way to move the food in one direction (usually downstream, but occasionally upstream for short distances); this is called peristalsis. If you looked at the intestine, you would see a ring of contraction that moves along pushing contents ahead of it. At other times, the muscles in adjacent parts of the gastrointestinal tract squeeze more or less independently of each other: this has the effect of mixing the contents but not moving them up or down. Both kinds of contraction patterns are called motility. The gastrointestinal tract is divided into four distinct parts: the esophagus, stomach, small intestine, and large intestine (colon). They are separated from each other by special muscles called sphincters which normally stay tightly closed and which regulate the movement of food and food residues from one part to another. Each part of the gastrointestinal tract has a unique function to perform in digestion, and as a result each part has a distinct type of motility and sensation. When motility or sensations are not appropriate for performing this function, they cause symptoms such as bloating, vomiting, constipation, or diarrhea which are associated with subjective sensations such as pain, bloating, fullness, and urgency to have a bowel movement.
    [Show full text]
  • Bacterial Motility م.م رنا مشعل Bacterial Motility
    Bacterial Motility م.م رنا مشعل Bacterial Motility The ability of an organism to move by itself is called motility. A large number of bacteria are motile. Most possess one or more flagella on their surface that allow them to swim. Bacterial flagella are tiny hair like organelles of locomotion. Originating in the cytoplasm beneath the cell wall, they extend beyond the cell, usually equaling or exceeding it in length. Their fine protein structure requires special staining techniques for demonstrating them with the light microscope. Site of Flagella The pattern of flagellation is an important feature in identification of motile bacteria. Monotrichous is a single polar flagellum. Amphitrichous one or more flagella at both poles. Lophotrichous tufts of flagella at one end pole. Peritrichous flagella surrounding the perimeter of the cell. • Bacterial Motility Flagella compose from: . Filament – Composed of a protein called flagellin . Hook – Base of filament near cell wall . Basal Body - Anchors filament & hook to cell wal Types of movement : . Run : straight line movement occurs when the flagella rotates couter clockwise. Tumbles : turning the direction by clockwise movement of the flagella. Flagella are anchored by pairs of rings associated with the plasma membrane and cell wall. Gram positive bacteria have only the inner pair of rings. Motility testing Motility could be detected by: 1) Hanging Drop technique. 2) Flagella stain. 3) Semi-Solid media Inoculation. 1) Hanging Drop slide The slide for a hanging drop is ground with a concave well in the centre; the cover glass holds a drop of the suspension. When the cover glass is inverted over the well of the slide, the drop hangs from the glass in the hollow concavity of the slide.
    [Show full text]
  • Examination and Processing of Human Semen
    WHO laboratory manual for the Examination and processing of human semen FIFTH EDITION WHO laboratory manual for the Examination and processing of human semen FIFTH EDITION WHO Library Cataloguing-in-Publication Data WHO laboratory manual for the examination and processing of human semen - 5th ed. Previous editions had different title : WHO laboratory manual for the examination of human semen and sperm-cervical mucus interaction. 1.Semen - chemistry. 2.Semen - laboratory manuals. 3.Spermatozoa - laboratory manuals. 4.Sperm count. 5.Sperm-ovum interactions - laboratory manuals. 6.Laboratory techniques and procedures - standards. 7.Quality control. I.World Health Organization. ISBN 978 92 4 154778 9 (NLM classifi cation: QY 190) © World Health Organization 2010 All rights reserved. Publications of the World Health Organization can be obtained from WHO Press, World Health Organization, 20 Avenue Appia, 1211 Geneva 27, Switzerland (tel.: +41 22 791 3264; fax: +41 22 791 4857; e-mail: [email protected]). Requests for permission to reproduce or translate WHO publications— whether for sale or for noncommercial distribution—should be addressed to WHO Press, at the above address (fax: +41 22 791 4806; e-mail: [email protected]). The designations employed and the presentation of the material in this publication do not imply the expres- sion of any opinion whatsoever on the part of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. Dotted lines on maps represent approximate border lines for which there may not yet be full agreement. The mention of specifi c companies or of certain manufacturers’ products does not imply that they are endorsed or recommended by the World Health Organization in preference to others of a similar nature that are not mentioned.
    [Show full text]
  • The Two Motility Systems Ofmyxococcus Xanthus Show
    Proc. Natl. Acad. Sci. USA Vol. 90, pp. 3378-3382, April 1993 Microbiology The two motility systems of Myxococcus xanthus show different selective advantages on various surfaces (gliding bacterium/swarming/fruiting/video microscopy) WENYUAN SHI AND DAVID R. ZUSMAN Department of Molecular and Cell Biology, 401 Barker Hall, University of California, Berkeley, CA 94720 Communicated by Horace A. Barker, January 8, 1993 (received for review August 26, 1992) ABSTRACT Myxococcus xanthus, a bacterium that forms In this paper, we report that A-motility and S-motility show fruiting bodies, moves by gliding motility utilizing dual motility different selective advantages on different surfaces: A-mo- systems that differ both genetically and morphologically [sys- tility allows cells to move better than S-motility on relatively tem A, having at least 21 genetic loci and moving mainly single firm and dry surfaces, whereas S-motility allows cells to cells, and system S, having at least 10 genetic loci and moving move much better on relatively soft and wet surfaces. These groups (rafts) of cells] [Hodgkin, J. & Kaiser, D. (1979) Mol. results show that, like flagellated bacteria, the dual motility Gen. Genet. 172, 177-191]. In this study, we found that A- and systems in gliding bacteria allow cells to adapt to a variety of S-gliding-motility systems have different selective advantages physiological and ecological environments. on surfaces containing different concentrations of agar. We observed that colonies of A+S- cells (A-motile cells) swarmed better than A-S+ cells (S-motile cells) on relatively firm and MATERIALS AND METHODS dry surfaces (e.g., 1.5% agar).
    [Show full text]