DOCSLIB.ORG

Unit 3 Metazoa - Origin and Evolution

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Unit 3 Metazoa - Origin and Evolution UNIT 3 METAZOA - ORIGIN AND EVOLUTION Structure 3.1 Introduction Objectives 3.2 Levels of Body Organisation 3.3 Characteristics of Metazoa 3.4 Symmetry Asymmetrical and Spherical Radial and Biradial I Bilateral 3.5 Developmental Patterns Cleavage Fate of Blastopore 3.6 Germ Layers 3.7 Body Cavity and Coelom Pseudocoelom Coelom 3.8 Cephalisation and Segmentation 3.9 Origin and Evolution of Metazoa Syncytial Theory Colonial Theory Polyphyletic Theory Evolution of Metazoa 3.10 Summary 3.11 Terminal Questions 3.12 Answers 3.1 INTRODUCTION You have already seen in Unit-1 that in the two kingdom classification, the unicellular 'animals' used to be clubbed together under a single phylum Protozoa that constituted sub-kingdom - Protozoa. The rest of the animals, all multicellular, were grouped under the sub-kingdom Metazoa under various phyla (the corresponding grouping for plants was Protophyta and Metaphyta). However, under the present concept of Flve Kingdom Classification, this grouping has no relevance. Still, we often continue to use the term Metazoa to refer to the Animalia of the five kingdom classification. In th~sUn~t we start with an explanation of the levels of body organisation in animals and the baslc animal bodjr plan. However, diverse the different invertebrates and vertebrates may appear to the eye, it is possible to group them in four master body plans. These are the unicellular plan, the cell aggregate plan, blind sac plan and tube within a tube plan. The protozoans fall into the first category and the rest three structural plans are seen in the metazoans. We next list out the characteristic features of metazoans. We shall also discuss those features that are considered of fundamental importance for describing and understanding the structure and classification of any animal. These characters are: (i) cleavage patterns and number of genn layers it has been derived from; (ii) its body symmetry; (iii) nature of body cavity; (iv) segmentation and cephalisation,. It would be useful if you rev~se Block-3 of the course Developmental Biology (LSE-06) before reading this unit as most of the concepts discussed there would help you to understand this Unit better. In later sections of the unit we will consider the variou? theories related to origln and evolution of metazoans or the Animalia. Objectives After studying this unit you should be able to: describe various levels of body organisation of animals; e describe the various cleavage patterns found in animals; identify the various types of gem layers and describe the functions of their ~ctazor- mgin and ~volution derivatives; identify the animal groups based on their symmetry;. describe the different types of body cavities, segmentation, cephalisation and theu functional significance; classify animals on the basis of their structural organisation; discuss the origin and evolution of Animalia. 3.2 LEVELS OF BODY .ORGANISATION You have learnt in your earlier course LSE-01 about the levels of organisation of matter. You may recall that the smallest structural units of all matter are subatomic~particles, mainly electrons, protons and neutrons. The next larger units are atoms and many atoms get together to form combinations called compounds which are variously joined together to give a higher level of organisation called complexes of compounds. Such levels of matter can be viewed as a pyramid (Fig. 3.1). Chemical / compounds \ / Atoms \ Sub atomic particles Fig. 3.1: Levels of organisation of matter. b In this pyramid any given level contains all lower, levels as its,component and itself is 1 also a component of all higher levels. For example, atoms contain subatomic particles as components, and atoms are themselves components of chemical compounds. Similarly, in ;I living matter, complexes of compounds occur as submicroscopic and mic~oscopicbodies 4 called organelles, capable of carrying on specialised functions within the cell. Organisms which are made of just one cell are the simplest and the most primitive creatures called unicellular organisms. Their level of body organisation is at the lowest and is called protoplasmic level of body organisation. If we try and fit the metazoan body organisation into a pyramid mode, the protoplasmic level will be at the bottom. As the organisms evolved from unicellular to multicellular grade their level of body orianisation also changed from simple to complex. Fig. 3.2: Level of body organlaation. Look at the Figure 3.2, the next higher level of organisation is the cellular level. This is really an aggregation of cells that are functionally differentiated. A division of labour is evident so that some cells are specialised for reproduction some for nutrition. Among the metazoans, Placozoa and Mesozoa are.said to belong to the cellular level of body I organisation (Fig. 3.3 e and h). Diversity of Animal Life-I some authorities place the sponges (porifera) among this group too because they have (Organisation) several cell types differentiated for various fu'nctions but there is no true tissue orpanisation yet. (Fig. 3.3 c). The phylum Placozoa contains a single species of a minute marine animal Trichoplar adharens composed of a dorsal and ventral epithelial layer enclosing loose mesenchyme like cells. Mesozoans comprise some 50 species of small parasitic worms that have simple structures made up of 20-30 ciliated cells covering a few reproductive cells. Fig. 3.3: (a) Cellular level of body organisation in mesozoan - Rhopcllura. (after Hyman) (b) a placozoan (after Margurlis & Schwartz 1982) (c) L.S. asconoid sponge. As you already know a tissue is a group of cells similar in origin and structure that perform a specific function. The next level, is the tissue level of body organisation which can be seen in coelenterates (Cnidaria and Ctenophora). These are made up of two germ layers ectoderm forming epidermis and endoderm forming the gastrodemis. The jelly fishes and their relatives are considered as the beginning of tissue organisation - and an excellent example of tissues, in Cnidarians is the nerve net in which the nerve cells and their processes form a definite tissue structure with the function of coordination (Fig. 3.4). The next higher level of body organisation as seen in the pyramid is the organ. Organs are usually made up of more than one kind of tissues. This is already seen in some cnidarians, ctenophores and the flatworms or Platyhelminthes in which there are well defined organs such as the eye and reproductive organs (Fig. 3.5). Fig. 3.4: Tissue grade of organisation - nerve net in jelly fish. lenlacular shcalh - aboral canal Fig. 3.5: Organ level of organisation in a typical ctenophore. When organs work together to perform a specific function we have the highest level of body organisation i.e. the organ system level of body organisation. The systems are associated with basic body functions. This type of body organisation is seen for the first time in Platyhelminthes (Fig. 3.6) which have for example, a digestive system distinct from a well developed reproductive system. From this phylum to mammals, all animals have the highest level of body organisation. Metazoa - Origin and Evolutiorr Fig. 3.6: Organ system level of organisation in Plan& a) digestive system b) excretory systenl c) reproductive system. -- 3.3 CHARACTERISTICS OF METAZOA From Unit-2 you know that the unicellular protozoans are highly versatile and successful organisms that show remarkable organisation and division of labour within the confines of the single cell. This diversity is achieved by varying the structure of their organelles at the sub-cellular level. The Metazoa or the multicellular animals have achieved their structural diversity by varying lheir cells that have become specialised to perform different functions. These cells are normally incapable of independent existence. Let us list out some of the features that characterise metazoans. 1. Members of Metazoa possess a complex multicellular structural organization which may include the presence of tissues, organs and organ systems. 2. In the life history of metazoans, typically a fertilized egg passes through a blastula stage in the course of its early embryonic development before changing into an . adult. 3. Since metazoans are multicellular they are relatively larger in size than unicellular protozoans. Naturally, their ntitritional requirements are more and they have to search for food. Consequently, locomotion in metazoans is highly developed and for this purpose they have evolved contractile muscular elements and nervous structures. 4. The ability for locomotions has influenced the shape of the metazoan animals which in turn has conferred specific types of symmetries to metazoan groups. 5. Most of the metazoans show differentiation of the anterior end or head (cephalization); associated with cephalisation, there is the centralization of the nervous system in the head region. Although all metazoans share some characteristic features, their body plans differ in symmetry, internal organisation, developmental patterns and modes of formation of,body cavity. These differences provide us a means of grouping them or organising them into different phyla. Let 3s discuss these features one by 'one. All living organisms have some body shape and form. The general body plan of animals may be organized in one of several ways (Fig. 3.7 a-f). 59 Diversity of Animal Life-I IOrganisation) (b) actinophrys tentacular Ib p haryn y eal plane Flg. 3.7: Different types of body symmetries a) asymmetrical b) spherically symmetrical, (c-d) radially symmetrical. (e) biradially symmetrical (f) bilaterally symmetrical. Arrangement of parts or organs on either side of an imaginary dividing line or around a common axis or radially around a point so that opposite parts are mirror images of one another is called symmetry. There are two broad divisions of symmetry, (i) primary, or embryonic (ii) secondary, or adult. .The latter may or may not be the same as the primary one.
Load more

Recommended publications
  • Sak/Plk4 and Mitotic Fidelity
    Oncogene (2005) 24, 306–312 & 2005 Nature Publishing Group All rights reserved 0950-9232/05 $30.00 www.nature.com/onc Sak/Plk4 and mitotic fidelity Carol J Swallow1,2, Michael A Ko1,2, Najeeb U Siddiqui1,3,4, John W Hudson5 and James W Dennis*,1,3,4 1Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Ave. R988, Toronto, Ontario, Canada M5G 1X5; 2Department of Surgery, University of Toronto, Ontario, Canada; 3Department of Microbiology and Medical Genetics, University of Toronto, Ontario, Canada; 4Department of Laboratory Medicine and Pathobiology, University of Toronto, Ontario, Canada; 5Department of Biological Sciences, University of Windsor, Ontario, Canada Sak/Plk4 differs from other polo-like kinases in having (Fernebro et al., 2002). Mutation of classical tumor only a single polo box, which assumes a novel dimer fold suppressor genes follows the Knudsen 2-hit model, that localizes to the nucleolus, centrosomes and the whereby loss of the wild-type allele as a ‘second hit’ cleavage furrow.Sak expression increases gradually in S frequently results in relaxed cellular growth controls through M phase, and Sak is destroyed by APC/C (Knudson, 1971). Inherited cancer syndromes such as dependent proteolysis.Sak-deficient mouse embryos Li-Fraumeni (p53, Chk2) and ataxia telangiectasia arrest at E7.5 and display an increased incidence of (ATM) are examples of autosomal recessive mutations apoptosis and anaphase arrest.Sak þ /À mice are haploin- in checkpoint proteins that normally delay the cell cycle sufficient for tumor suppression, with spontaneous tumors in response to DNA damage and environmental stresses developing primarily in the liver with advanced age.
    [Show full text]
  • S41598-020-68694-9.Pdf
    www.nature.com/scientificreports OPEN Delayed cytokinesis generates multinuclearity and potential advantages in the amoeba Acanthamoeba castellanii Nef strain Théo Quinet1, Ascel Samba‑Louaka2, Yann Héchard2, Karine Van Doninck1 & Charles Van der Henst1,3,4,5* Multinuclearity is a widespread phenomenon across the living world, yet how it is achieved, and the potential related advantages, are not systematically understood. In this study, we investigate multinuclearity in amoebae. We observe that non‑adherent amoebae are giant multinucleate cells compared to adherent ones. The cells solve their multinuclearity by a stretchy cytokinesis process with cytosolic bridge formation when adherence resumes. After initial adhesion to a new substrate, the progeny of the multinucleate cells is more numerous than the sibling cells generated from uninucleate amoebae. Hence, multinucleate amoebae show an advantage for population growth when the number of cells is quantifed over time. Multiple nuclei per cell are observed in diferent amoeba species, and the lack of adhesion induces multinuclearity in diverse protists such as Acanthamoeba castellanii, Vermamoeba vermiformis, Naegleria gruberi and Hartmannella rhysodes. In this study, we observe that agitation induces a cytokinesis delay, which promotes multinuclearity. Hence, we propose the hypothesis that multinuclearity represents a physiological adaptation under non‑adherent conditions that can lead to biologically relevant advantages. Te canonical view of eukaryotic cells is usually illustrated by an uninucleate organization. However, in the liv- ing world, cells harbouring multiple nuclei are common. Tis multinuclearity can have diferent origins, being either generated (i) by fusion events between uninucleate cells or by (ii) uninucleate cells that replicate their DNA content without cytokinesis.
    [Show full text]
  • Arxiv:2011.01294V2 [Q-Bio.PE] 23 Nov 2020 of Body Plans
    Studying evolution of the primary body axis in vivo and in vitro Kerim Anlas1, Vikas Trivedi1;2;∗ The metazoan body plan is established during early embryogenesis via collective cell rearrangements and evolutionarily conserved gene networks, as part of a process com- monly referred to as gastrulation. While substantial progress has been achieved in terms of characterizing the embryonic development of several model organisms, underlying principles of many early patterning processes nevertheless remain enigmatic. Despite the diversity of (pre-)gastrulating embryo and adult body shapes across the animal kingdom, the body axes, which are arguably the most fundamental features, generally remain identical between phyla. Recently there has been a renewed appreciation of ex vivo and in vitro embryo-like systems to model early embryonic patterning events. Here, we briefly review key examples and propose that similarities in morphogenesis as well as associated gene expression dynamics may reveal an evolutionarily conserved developmental mode as well as provide further insights into the role of external or extraembryonic cues in shaping the early embryo. In summary, we argue that embryo-like systems can be employed to inform previously uncharted aspects of animal body plan evolution as well as associated patterning rules. 1. Introduction In this perspective, we outline metazoan body axes and con- Metazoans display vast morphological diversity, yet body served initial patterning genes Wnt and Bra/T, followed by a plans can universally be distilled to the presence of one to brief review and comparison of mostly recent embryo-like sys- three body axes. Contrasted with protists, a characteristic tems in an evolutionary context.
    [Show full text]
  • Nuclear and Genome Dynamics in Multinucleate Ascomycete Fungi
    Current Biology 21, R786–R793, September 27, 2011 ª2011 Elsevier Ltd All rights reserved DOI 10.1016/j.cub.2011.06.042 Nuclear and Genome Dynamics Review in Multinucleate Ascomycete Fungi Marcus Roper1,2, Chris Ellison3, John W. Taylor3, to enhance phenotypic plasticity [5] and is also thought to and N. Louise Glass3,* contribute to fungal virulence [6–8]. Recent and ongoing work reveals two fundamental chal- lenges of multinucleate fungal lifestyles, both in the presence Genetic variation between individuals is essential to evolu- and absence of genotypic diversity — namely, the coordina- tion and adaptation. However, intra-organismic genetic tion of populations of nuclei for growth and other behaviors, variation also shapes the life histories of many organisms, and the suppression of nucleotypic competition during including filamentous fungi. A single fungal syncytium can reproduction and dispersal. The potential for a mycelium to harbor thousands or millions of mobile and potentially harbor fluctuating proportions and distributions of multiple genotypically different nuclei, each having the capacity genotypes led some 20th century mycologists to argue for to regenerate a new organism. Because the dispersal of life-history models that focused on nuclei as the unit of asexual or sexual spores propagates individual nuclei in selection, and on the role of nuclear cooperation and compe- many of these species, selection acting at the level of tition in shaping mycelium growth and behavior [9,10].In nuclei creates the potential for competitive and coopera- particular, nuclear totipotency creates potential for conflict tive genome dynamics. Recent work in Neurospora crassa between heterogeneous nuclear populations within a myce- and Sclerotinia sclerotiorum has illuminated how nuclear lium [11,12].
    [Show full text]
  • Multinucleate Cell Angiohistiocytoma
    To protect the rights of the author(s) and publisher we inform you that this PDF is an uncorrected proof for internal business use only by the author(s), editor(s), reviewer(s), Elsevier and typesetter Toppan Best-set. It is not allowed to publish this proof online or in print. This proof copy is the copyright property of the publisher and is confidential until formal publication. These proofs may contain color(colour) figures. Those figures may print black and white in the final printed book if a color(colour) print product has not been planned. The color(colour) figures will appear in color(colour) in all electronic versions of this book. s0060 MULTINUCLEATE CELL ANGIOHISTIOCYTOMA s0065 Definition • Fibroblast-like and histiocyte-like mononuclear cells u0390 p0300 • A distinctive benign dermal proliferation composed • Thickened collagen bundles, frequently hyalinized u0395 of thin-walled capillaries and veins, admixed with • Occasional inflammatory cells, predominantly u0400 scattered multinucleated cells lymphocytes • Hemorrhage absent, no hemosiderin deposition u0405 s0070 Clinical features • Decreased elastic fibers in the dermis can be observed u0410 s0075 Epidemiology • Overlying epidermis normal, but can also be u0415 p0310 • Female predominance (F:M = 3 : 1) hyperplastic u0275 • Middle-aged adult patients • Proliferation restricted to upper and middermis u0420 s0080 Presentation Immunopathology/special stains s0100 p0325 • Slowly growing single or multiple firm, red-brown to • Multinucleated cells display variable CD68 positivity
    [Show full text]
  • Host-Parasite Relationships of Atalodera Spp. (Heteroderidae) M
    234 Journal of Nematology, Volume 15, No. 2, April 1983 and D. I. Edwards. 1972. Interaction of Meloidogyne 18. Volterra, V. 1931. Variations and fluctuations naasi, Pratylenchus penetrans, and Tylenchorhyn- of the number of individuals in animal species chus agri on creeping bentgrass. J. Nematol. 4:~ living together. Pp. 409-448 tn R. N. Chapman ed. 162-165. Animal ecology. New York: McGraw-Hill. Host-Parasite Relationships of Atalodera spp. (Heteroderidae) M. ]~'IUNDO-OCAMPOand J. G. BALDWIN r Abstract: Atalodera ucri, Wouts and Sher, 1971, and ,4. lonicerae, (Wonts, 1973) Luc et al., 1978, induce similar multinucleate syncytia in roots of golden bush and honeysuckle, respec- tively. The syncytium is initiated in the cortex; as it expands, it includes several partially delimited syncytial units and distorts vascular tissue. Outer walls of the syncytium are rela- tively smooth and thickest near the feeding site of the nematode; inner walls are interrupted by perforations which enlarge as syncytial units increa~ in size. The cytoplasm of the syncytium is granular and includes numermts plastids, mit(~chondria, vacuoles, Golgi, and a complex network of membranes. Nuclei are greatly enlarged and amoeboid in shape. Although more than one nucleus sometimes occur in a given syncytial unit, no mitotic activity was observed. Syncytia induced by species of Atalodera chiefly differ from those of Heterodera sensu lato by the absence of cell wall ingrowths; wall ingrowths increase solute transport and characterize transfer cells. In syncytia of Atalodera spp., a high incidence of pits and pit fields in walls adjacent to vasctdar elements suggests that in this case plasmodesmata provide the pathway for increased entry of sohttes.
    [Show full text]
  • Physarum Polycephalum (Plasmodial Slime Mold)
    Physarum polycephalum (plasmodial slime mold) Species: polycephalum Genus: Physarum Family: Physaraceae Order: Physarales Class: Myxomycetes Phylum: Mycetozoa Kingdom: Amoebozoa Conditions for Customer Ownership We hold permits allowing us to transport these organisms. To access permit conditions, click here. Never purchase living specimens without having a disposition strategy in place. There are currently no USDA permits required for this organism. In order to protect our environment, never release a live laboratory organism into the wild. Primary Hazard Considerations Always wash your hands thoroughly before and after you handle your cultures, or anything it has touched. It is recommended to use gloves when working with mold, fungus, or bacteria. Availability Physarum is available year round. Care Habitat • Plasmodial stage are shipped in a Petri dish on Physarum agar with oats. Your Physarum should be bright yellow in color, and fan shaped. If your Physarum takes on a different appearance it may be contaminated. Contaminated cultures occur when a foreign specimen (something other than Physarum) makes its way onto your culture. This culture should be stored at room temperature in a dark place. The culture should be viable for about 1–2 weeks in its current container. • Sclerotia are hardened masses of irregular form consisting of many minute cell-like components. These are shipped on cut strips of filter paper in a tube. The culture should be stored at room temperature and can be stored in this stage for several months. Care: • Physarum is subcultured onto Physarum agar, and is incubated at room temperature or 25 °C. To maintain viability, plasmodial Physarum should be subcultured weekly.
    [Show full text]
  • Mechanisms of Epithelial Morphogenesis and Integrity During Nematostella Vectensis Development and Shigella Pathogenesis by ASHL
    Mechanisms of epithelial morphogenesis and integrity during Nematostella vectensis development and Shigella pathogenesis BY ASHLEIGH E FRITZ Submitted to the graduate degree program in Cell Biology and Anatomy and the Graduate Faculty of the University of Kansas in partial fulfillment of the requirements for the degree of Doctor of Philosophy. ________________________________ Matthew C. Gibson, Ph.D., Co-Chair _______________________________ William H. Kinsey, Ph.D., Co-Chair ________________________________ Lane K. Christenson, Ph.D. _______________________________ Jennifer L. Gerton, Ph.D. ________________________________ Brenda J. Rongish, Ph.D. Date Defended: March 28, 2014 The Dissertation Committee for Ashleigh E Fritz certifies that this is the approved version of the following dissertation: Mechanisms of epithelial morphogenesis and integrity during Nematostella vectensis development and Shigella pathogenesis ________________________________ Matthew C. Gibson, Ph.D., Co-Chair ________________________________ William H. Kinsey, Ph.D., Co-Chair Date approved: April 4, 2014 ii Abstract The transition to animal multicellularity involved the evolution of single cells organizing into sheets of tissue. The advent of tissues allowed for specialization and diversification, which led to the formation of complex structures and a variety of body plans. These epithelial tissues undergo morphogenesis during animal development, and the establishment and maintenance of their polarity and integrity is crucial for homeostasis and prevention of pathogenesis.
    [Show full text]
  • The Role of DE-Cadherin During Cellularization, Germ Layer Formation and Early Neurogenesis in the Drosophila Embryo
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Developmental Biology 270 (2004) 350–363 www.elsevier.com/locate/ydbio The role of DE-cadherin during cellularization, germ layer formation and early neurogenesis in the Drosophila embryo Fay Wang, Karin Dumstrei, Thomas Haag, and Volker Hartenstein* Department of Molecular Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA Received for publication 24 November 2003; revised 4 March 2004; accepted 5 March 2004 Available online 15 April 2004 Abstract The Drosophila E-cadherin homolog, DE-cadherin, is expressed and required in all epithelial tissues throughout embryogenesis. Due to a strong maternal component of DE-cadherin, its early function during embryogenesis has remained elusive. The expression of a dominant negative DE-cadherin construct (UAS-DE-cadex) using maternally active driver lines allowed us to analyze the requirements for DE-cadherin during this early phase of development. Maternally expressed DE-cadex result in phenotype with variable expressivity. Most severely affected embryos have abnormalities in epithelialization of the blastoderm, resulting in loss of the blastodermal cells’ apico-basal polarity and monolayered structure. Another phenotypic class forms a rather normal blastoderm, but shows abnormalities in proliferation and morphogenetic movements during gastrulation and neurulation. Mitosis of the mesoderm occurs prematurely before invagination, and proliferation in the ectoderm, normally a highly ordered process, occurs in a random pattern. Mitotic spindles of ectodermal cells, normally aligned horizontally, frequently occurred vertically or at an oblique angle. This finding further supports recent findings indicating that, in the wild-type ectoderm, the zonula adherens is required for the horizontal orientation of mitotic spindles.
    [Show full text]
  • Slime Molds on Home Lawns
    LAWN & GARDEN Slime Molds on Home Lawns ► Slime molds rarely damage lawns, but their appearance is unsightly to homeowners. Learn the symptoms, cause, and control. Slime molds commonly occur on all warm- and cool- season turfgrasses across Alabama. Most slime mold causing fungi on turfgrasses belong to the genera of Physarum, Fuligo, and Mucilago. Slime molds are saprophytic fungal-like organisms that obtain their nutrients from dead or decaying organic matter in soil or thatch. Slime molds are most prevalent following prolonged periods of leaf wetness, which favors growth. Slime molds use living turfgrass strictly for structural support and rarely cause damage to lawns. However, the sudden appearance of the crusty, gray to black fruiting bodies of a slime mold on the leaves of a manicured lawn often causes homeowners a great deal of anxiety. At times, homeowners mistake slime mold appearance with chemical spills and become concerned about the health of their lawns. Alabama’s humid, warm climate is quite conducive to slime mold activity, particularly during extended periods of rain in late spring and summer. Areas with poor drainage and Figure 2. Slime mold pustules on residential turf. heavy thatch (dead turfgrass tissue lying between the green vegetation of the grass above and the root system below) also favor slime mold growth. Slime molds may Symptoms appear in the same area of a lawn from year to year. Various species of slime molds can result in the growth of many small, round pustules called sporangia (fruiting bodies) on turfgrass leaves in small circular to irregular patches, usually 4 to 8 inches in diameter (figure 1).
    [Show full text]
  • Real-Time Dynamics of Plasmodium NDC80 Reveals Unusual Modes of Chromosome Segregation During Parasite Proliferation
    bioRxiv preprint doi: https://doi.org/10.1101/767830; this version posted May 12, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. Real-time dynamics of Plasmodium NDC80 reveals unusual modes of chromosome segregation during parasite proliferation Mohammad Zeeshan1#, Rajan Pandey1#, David J.P. Ferguson2,3, Eelco C. Tromer4, Robert Markus1, Steven Abel5, Declan Brady1, Emilie Daniel1, Rebecca Limenitakis6, Andrew R. Bottrill7, Karine G. Le Roch5, Anthony A. Holder8, Ross F. Waller4, David S. Guttery9 and Rita Tewari1* 1School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham, NG7 2UH, UK; 2Nuffield Department of Clinical Laboratory Science, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, UK; 3Department of Biological and Medical Sciences, Faculty of Health and Life Science, Oxford Brookes University, Gipsy Lane, Oxford OX3 0BP, UK; 4Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK; 5Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, California, United States of America; 6Institute of Cell Biology, University of Bern, Bern 3012, Switzerland; 7School of Life Sciences, Gibbelt Hill Campus, University of Warwick, Coventry, CV4 7AL, UK; 8Malaria Parasitology Laboratory, The Francis Crick Institute, London, NW1 1AT, UK; 9Leicester Cancer Research Centre, University of Leicester, Leicester, LE2 7LX, UK. #These authors contributed equally: Mohammad Zeeshan, Rajan Pandey *For correspondence Rita Tewari: [email protected] Short title: Spatiotemporal Kinetochore dynamics in Plasmodium 1 bioRxiv preprint doi: https://doi.org/10.1101/767830; this version posted May 12, 2020.
    [Show full text]
  • Farrell Ofarrell Manuscript Preprint
    1 / 29 From egg to gastrula: How the Table of Contents 1. Introduction cell cycle is remodeled during 2. Early development in Drosophila the Drosophila mid-blastula 3. Transitions in embryonic regulation transition. 4. Why have a specialized, exceptionally rapid early cell cycle program? Jeffrey A. Farrell (1) and Patrick H. O’Farrell (2) 5. Achieving speed 5.1. Dependence only on maternal (1) Department of Molecular and Cellular contributions Biology Harvard University, Cambridge, MA 5.2. Lack of gap phases 02138 [email protected] 5.3. Rapid S phase (2) Department of Biophysics and 6. The consequences of speed Biochemistry, University of California, San 7. A mechanistic view of pre-MBT cell cycle Francisco 94158, [email protected] slowing Corresponding author: Patrick H. O’Farrell 7.1. DNA replication and the replication checkpoint time the pre-MBT cycles Running title: Slowing the cell cycle at the 7.2. Why does DNA replication slow MBT during the early cycles? 8. The dramatic lengthening of the cell Keywords: Drosophila, MBT, maternal zygotic cycle at the MBT transition, replication, G2, cell cycle 8.1. Cdc25 phosphatase activity determines the length of interphase 14 Abstract 8.2. Maternal Cdc25 is depleted via Many, if not most, embryos begin destruction of Cdc25/Twine protein development with extremely short cell 8.3. Inhibitory phosphorylation cycles that exhibit unusually rapid DNA collaborates with an inhibitor of Cdk1 replication and no gap phases. The 9. The transition is active and dependent commitment to the cell cycle in the early on transcription embryo appears to preclude many other 10.
    [Show full text]