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Heslop-Harrison G, Nakabayashi K, Espinosa-Ruiz A, Robertson F, Baines R, Thompson CRL, Hermann K, Alabadí D, Leubner-Metzger G, Williams RSB. Functional mechanism study of the allelochemical myrigalone A identifies a group of ultrapotent inhibitors of ethylene biosynthesis in plants. PLANT COMMUNICATIONS 2024:100846. [PMID: 38460510 DOI: 10.1016/j.xplc.2024.100846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 12/21/2023] [Accepted: 02/14/2024] [Indexed: 03/11/2024]
Abstract
Allelochemicals represent a class of natural products released by plants as root, leaf, and fruit exudates that interfere with the growth and survival of neighboring plants. Understanding how allelochemicals function to regulate plant responses may provide valuable new approaches to better control plant function. One such allelochemical, Myrigalone A (MyA) produced by Myrica gale, inhibits seed germination and seedling growth through an unknown mechanism. Here, we investigate MyA using the tractable model Dictyostelium discoideum and reveal that its activity depends on the conserved homolog of the plant ethylene synthesis protein 1-aminocyclopropane-1-carboxylic acid oxidase (ACO). Furthermore, in silico modeling predicts the direct binding of MyA to ACO within the catalytic pocket. In D. discoideum, ablation of ACO mimics the MyA-dependent developmental delay, which is partially restored by exogenous ethylene, and MyA reduces ethylene production. In Arabidopsis thaliana, MyA treatment delays seed germination, and this effect is rescued by exogenous ethylene. It also mimics the effect of established ACO inhibitors on root and hypocotyl extension, blocks ethylene-dependent root hair production, and reduces ethylene production. Finally, in silico binding analyses identify a range of highly potent ethylene inhibitors that block ethylene-dependent response and reduce ethylene production in Arabidopsis. Thus, we demonstrate a molecular mechanism by which the allelochemical MyA reduces ethylene biosynthesis and identify a range of ultrapotent inhibitors of ethylene-regulated responses.
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Affiliation(s)
- George Heslop-Harrison
- Centre for Biomedical Sciences, Department of Biological Sciences, Royal Holloway University of London, Egham TW20 0EX, UK
| | - Kazumi Nakabayashi
- Centre for Plant Molecular Sciences, Department of Biological Sciences, Royal Holloway University of London, Egham TW20 0EX, UK
| | - Ana Espinosa-Ruiz
- Instituto de Biología Molecular y Celular de Plantas (CSIC-UPV), 46022 Valencia, Spain
| | - Francesca Robertson
- Centre for Biomedical Sciences, Department of Biological Sciences, Royal Holloway University of London, Egham TW20 0EX, UK; Centre for Plant Molecular Sciences, Department of Biological Sciences, Royal Holloway University of London, Egham TW20 0EX, UK
| | - Robert Baines
- Centre for Life's Origins and Evolution, Department of Genetics, Evolution and Environment, University College London, London, UK
| | - Christopher R L Thompson
- Centre for Life's Origins and Evolution, Department of Genetics, Evolution and Environment, University College London, London, UK
| | | | - David Alabadí
- Instituto de Biología Molecular y Celular de Plantas (CSIC-UPV), 46022 Valencia, Spain
| | - Gerhard Leubner-Metzger
- Centre for Plant Molecular Sciences, Department of Biological Sciences, Royal Holloway University of London, Egham TW20 0EX, UK
| | - Robin S B Williams
- Centre for Biomedical Sciences, Department of Biological Sciences, Royal Holloway University of London, Egham TW20 0EX, UK.
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Forget M, Adiba S, De Monte S. Single-cell phenotypic plasticity modulates social behavior in Dictyostelium discoideum. iScience 2023; 26:106783. [PMID: 37235054 PMCID: PMC10206496 DOI: 10.1016/j.isci.2023.106783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 02/09/2023] [Accepted: 04/26/2023] [Indexed: 05/28/2023] Open
Abstract
In Dictyostelium chimeras, "cheaters" are strains that positively bias their contribution to the pool of spores, i.e., the reproductive cells resulting from development. On evolutionary time scales, the selective advantage; thus, gained by cheaters is predicted to undermine collective functions whenever social behaviors are genetically determined. Genotypes; however, are not the sole determinant of spore bias, but the relative role of genetic and plastic differences in evolutionary success is unclear. Here, we study chimeras composed of cells harvested in different phases of population growth. We show that such heterogeneity induces frequency-dependent, plastic variation in spore bias. In genetic chimeras, the magnitude of such variation is not negligible and can even reverse the classification of a strain's social behavior. Our results suggest that differential cell mechanical properties can underpin, through biases emerging during aggregation, a "lottery" in strains' reproductive success that may counter the evolution of cheating.
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Affiliation(s)
- Mathieu Forget
- Institut de Biologie de l’Ecole Normale Supérieure, Département de Biologie, Ecole Normale Supérieure, CNRS, INSERM, PSL Research University, Paris, France
- Department of Evolutionary Theory, Max Planck Institute for Evolutionary Biology, Plőn, Germany
| | - Sandrine Adiba
- Institut de Biologie de l’Ecole Normale Supérieure, Département de Biologie, Ecole Normale Supérieure, CNRS, INSERM, PSL Research University, Paris, France
| | - Silvia De Monte
- Institut de Biologie de l’Ecole Normale Supérieure, Département de Biologie, Ecole Normale Supérieure, CNRS, INSERM, PSL Research University, Paris, France
- Department of Evolutionary Theory, Max Planck Institute for Evolutionary Biology, Plőn, Germany
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3
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Holstein TW. The role of cnidarian developmental biology in unraveling axis formation and Wnt signaling. Dev Biol 2022; 487:74-98. [DOI: 10.1016/j.ydbio.2022.04.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 04/07/2022] [Accepted: 04/11/2022] [Indexed: 12/12/2022]
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Arias Del Angel JA, Nanjundiah V, Benítez M, Newman SA. Interplay of mesoscale physics and agent-like behaviors in the parallel evolution of aggregative multicellularity. EvoDevo 2020; 11:21. [PMID: 33062243 PMCID: PMC7549232 DOI: 10.1186/s13227-020-00165-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 09/08/2020] [Indexed: 12/12/2022] Open
Abstract
Myxobacteria and dictyostelids are prokaryotic and eukaryotic multicellular lineages, respectively, that after nutrient depletion aggregate and develop into structures called fruiting bodies. The developmental processes and resulting morphological outcomes resemble one another to a remarkable extent despite their independent origins, the evolutionary distance between them and the lack of traceable homology in molecular mechanisms. We hypothesize that the morphological parallelism between the two lineages arises as the consequence of the interplay within multicellular aggregates between generic processes, physical and physicochemical processes operating similarly in living and non-living matter at the mesoscale (~10-3-10-1 m) and agent-like behaviors, unique to living systems and characteristic of the constituent cells, considered as autonomous entities acting according to internal rules in a shared environment. Here, we analyze the contributions of generic and agent-like determinants in myxobacteria and dictyostelid development and their roles in the generation of their common traits. Consequent to aggregation, collective cell-cell contacts mediate the emergence of liquid-like properties, making nascent multicellular masses subject to novel patterning and morphogenetic processes. In both lineages, this leads to behaviors such as streaming, rippling, and rounding-up, as seen in non-living fluids. Later the aggregates solidify, leading them to exhibit additional generic properties and motifs. Computational models suggest that the morphological phenotypes of the multicellular masses deviate from the predictions of generic physics due to the contribution of agent-like behaviors of cells such as directed migration, quiescence, and oscillatory signal transduction mediated by responses to external cues. These employ signaling mechanisms that reflect the evolutionary histories of the respective organisms. We propose that the similar developmental trajectories of myxobacteria and dictyostelids are more due to shared generic physical processes in coordination with analogous agent-type behaviors than to convergent evolution under parallel selection regimes. Insights from the biology of these aggregative forms may enable a unified understanding of developmental evolution, including that of animals and plants.
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Affiliation(s)
- Juan A Arias Del Angel
- Laboratorio Nacional de Ciencias de La Sostenibilidad, Instituto de Ecología, Universidad Nacional Autónoma de México, Mexico City, Mexico.,Centro de Ciencias de La Complejidad, Universidad Nacional Autónoma de México, Mexico City, Mexico.,Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY 10595 USA.,Programa de Doctorado en Ciencias Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | | | - Mariana Benítez
- Laboratorio Nacional de Ciencias de La Sostenibilidad, Instituto de Ecología, Universidad Nacional Autónoma de México, Mexico City, Mexico.,Centro de Ciencias de La Complejidad, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Stuart A Newman
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY 10595 USA
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5
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Wu Y, Cooper KM. Elastic modulus of Dictyostelium is affected by mechanotransduction. J Biol Phys 2019; 45:293-305. [PMID: 31363883 DOI: 10.1007/s10867-019-09529-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 07/09/2019] [Indexed: 11/28/2022] Open
Abstract
The stiffness of adherent mammalian cells is regulated by the elasticity of substrates due to mechanotransduction via integrin-based focal adhesions. Dictyostelium discoideum is an ameboid protozoan model organism that does not carry genes for classical integrin and can adhere to substrates without forming focal adhesions. It also has a life cycle that naturally includes both single-cellular and multicellular life forms. In this article, we report the measurements of the elastic modulus of single cells on varied substrate stiffnesses and the elastic modulus of the multicellular "slug" using atomic force microscopy (AFM) as a microindenter/force transducer. The results show that the elastic modulus of the Dictyostelium cell is regulated by the stiffness of the substrate and its surrounding cells, which is similar to the mechanotransduction behavior of mammalian cells.
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Affiliation(s)
- Yan Wu
- Department of Engineering Physics, University of Wisconsin-Platteville, 1 University Plaza, Platteville, WI, 53818, USA
| | - Kate M Cooper
- Department of Biology, Loras College, 1450 Alta Vista Street, Dubuque, IA, 52001, USA.
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A telomerase with novel non-canonical roles: TERT controls cellular aggregation and tissue size in Dictyostelium. PLoS Genet 2019; 15:e1008188. [PMID: 31237867 PMCID: PMC6592521 DOI: 10.1371/journal.pgen.1008188] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 05/10/2019] [Indexed: 11/19/2022] Open
Abstract
Telomerase, particularly its main subunit, the reverse transcriptase, TERT, prevents DNA erosion during eukaryotic chromosomal replication, but also has poorly understood non-canonical functions. Here, in the model social amoeba Dictyostelium discoideum, we show that the protein encoded by tert has telomerase-like motifs, and regulates, non-canonically, important developmental processes. Expression levels of wild-type (WT) tert were biphasic, peaking at 8 and 12 h post-starvation, aligning with developmental events, such as the initiation of streaming (~7 h) and mound formation (~10 h). In tert KO mutants, however, aggregation was delayed until 16 h. Large, irregular streams formed, then broke up, forming small mounds. The mound-size defect was not induced when a KO mutant of countin (a master size-regulating gene) was treated with TERT inhibitors, but anti-countin antibodies did rescue size in the tert KO. Although, conditioned medium (CM) from countin mutants failed to rescue size in the tert KO, tert KO CM rescued the countin KO phenotype. These and additional observations indicate that TERT acts upstream of smlA/countin: (i) the observed expression levels of smlA and countin, being respectively lower and higher (than WT) in the tert KO; (ii) the levels of known size-regulation intermediates, glucose (low) and adenosine (high), in the tert mutant, and the size defect's rescue by supplemented glucose or the adenosine-antagonist, caffeine; (iii) the induction of the size defect in the WT by tert KO CM and TERT inhibitors. The tert KO's other defects (delayed aggregation, irregular streaming) were associated with changes to cAMP-regulated processes (e.g. chemotaxis, cAMP pulsing) and their regulatory factors (e.g. cAMP; acaA, carA expression). Overexpression of WT tert in the tert KO rescued these defects (and size), and restored a single cAMP signaling centre. Our results indicate that TERT acts in novel, non-canonical and upstream ways, regulating key developmental events in Dictyostelium.
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Alam F, Kumar S, Varadarajan KM. Quantification of Adhesion Force of Bacteria on the Surface of Biomaterials: Techniques and Assays. ACS Biomater Sci Eng 2019; 5:2093-2110. [DOI: 10.1021/acsbiomaterials.9b00213] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Fahad Alam
- Biomaterials Processing and Characterization Laboratory, Materials Science and Engineering, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
- Department of Mechanical and Materials Engineering, Khalifa University of Science and Technology, Masdar Institute, Masdar City, Abu Dhabi United Arab Emirates
| | - Shanmugam Kumar
- Department of Mechanical and Materials Engineering, Khalifa University of Science and Technology, Masdar Institute, Masdar City, Abu Dhabi United Arab Emirates
| | - Kartik M. Varadarajan
- Department of Orthopaedic Surgery, Harvard Medical School, A-111, 25 Shattuck Street, Boston, Massachusetts 02115, United States
- Department of Orthopaedic Surgery, Harris Orthopaedics Laboratory, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts 02114, United States
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Matsushita K. Emergence of collective propulsion through cell-cell adhesion. Phys Rev E 2018; 97:042413. [PMID: 29758663 DOI: 10.1103/physreve.97.042413] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Indexed: 11/07/2022]
Abstract
The mechanisms driving the collective movement of cells remain poorly understood. To contribute toward resolving this mystery, a model was formulated to theoretically explore the possible functions of polarized cell-cell adhesion in collective cell migration. The model consists of an amoeba cell with polarized cell-cell adhesion, which is controlled by positive feedback with cell motion. This model cell has no persistent propulsion and therefore exhibits a simple random walk when in isolation. However, at high density, these cells acquire collective propulsion and form ordered movement. This result suggests that cell-cell adhesion has a potential function, which induces collective propulsion with persistence.
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9
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Shear force-based genetic screen reveals negative regulators of cell adhesion and protrusive activity. Proc Natl Acad Sci U S A 2017; 114:E7727-E7736. [PMID: 28847951 DOI: 10.1073/pnas.1616600114] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The model organism Dictyostelium discoideum has greatly facilitated our understanding of the signal transduction and cytoskeletal pathways that govern cell motility. Cell-substrate adhesion is downstream of many migratory and chemotaxis signaling events. Dictyostelium cells lacking the tumor suppressor PTEN show strongly impaired migratory activity and adhere strongly to their substrates. We reasoned that other regulators of migration could be obtained through a screen for overly adhesive mutants. A screen of restriction enzyme-mediated integration mutagenized cells yielded numerous mutants with the desired phenotypes, and the insertion sites in 18 of the strains were mapped. These regulators of adhesion and motility mutants have increased adhesion and decreased motility. Characterization of seven strains demonstrated decreased directed migration, flatness, increased filamentous actin-based protrusions, and increased signal transduction network activity. Many of the genes share homology to human genes and demonstrate the diverse array of cellular networks that function in adhesion and migration.
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10
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Matsushita K. Cell-alignment patterns in the collective migration of cells with polarized adhesion. Phys Rev E 2017; 95:032415. [PMID: 28415314 DOI: 10.1103/physreve.95.032415] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Indexed: 06/07/2023]
Abstract
Dictyostelium discoideum (Dd) utilizes inhomogeneities in the distribution of cell-cell adhesion molecules on cell membranes for collective cell migration. A simple example of an inhomogeneity is a front-side (leading-edge) polarization in the distribution at the early streaming stage. Experiments have shown that the polarized cell-cell adhesion induces side-by-side contact between cells [Beug et al., Nature (London) 274, 445 (1978)NATUAS0028-083610.1038/274445a0]. This result is counterintuitive, as one would expect cells to align front to front in contact with each other on the basis of front-side polarization. In this work, we theoretically examine whether front-side polarization induces side-by-side contact in collective cell migration. We construct a model for expressing cells with this polarization based on the two-dimensional cellular Potts model. By a numerical simulation with this model, we find cell-cell alignment wherein cells form lateral arrays with side-by-side contacts as observed in the experiments.
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11
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Huber RJ, Myre MA, Cotman SL. Aberrant adhesion impacts early development in a Dictyostelium model for juvenile neuronal ceroid lipofuscinosis. Cell Adh Migr 2016; 11:399-418. [PMID: 27669405 DOI: 10.1080/19336918.2016.1236179] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Neuronal ceroid lipofuscinosis (NCL), also known as Batten disease, refers to a group of severe neurodegenerative disorders that primarily affect children. The most common subtype of the disease is caused by loss-of-function mutations in CLN3, which is conserved across model species from yeast to human. The precise function of the CLN3 protein is not known, which has made targeted therapy development challenging. In the social amoeba Dictyostelium discoideum, loss of Cln3 causes aberrant mid-to-late stage multicellular development. In this study, we show that Cln3-deficiency causes aberrant adhesion and aggregation during the early stages of Dictyostelium development. cln3- cells form ∼30% more multicellular aggregates that are comparatively smaller than those formed by wild-type cells. Loss of Cln3 delays aggregation, but has no significant effect on cell speed or cAMP-mediated chemotaxis. The aberrant aggregation of cln3- cells cannot be corrected by manually pulsing cells with cAMP. Moreover, there are no significant differences between wild-type and cln3- cells in the expression of genes linked to cAMP chemotaxis (e.g., adenylyl cyclase, acaA; the cAMP receptor, carA; cAMP phosphodiesterase, pdsA; g-protein α 9 subunit, gpaI). However, during this time in development, cln3- cells show reduced cell-substrate and cell-cell adhesion, which correlate with changes in the levels of the cell adhesion proteins CadA and CsaA. Specifically, loss of Cln3 decreases the intracellular level of CsaA and increases the amount of soluble CadA in conditioned media. Together, these results suggest that the aberrant aggregation of cln3- cells is due to reduced adhesion during the early stages of development. Revealing the molecular basis underlying this phenotype may provide fresh new insight into CLN3 function.
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Affiliation(s)
- Robert J Huber
- a Department of Biology , Trent University , Peterborough , Ontario , Canada
| | - Michael A Myre
- b Department of Biological Sciences , University of Massachusetts Lowell , Lowell , Massachusetts , USA
| | - Susan L Cotman
- c Center for Human Genetic Research, Massachusetts General Hospital , Harvard Medical School , Boston , Massachusetts , USA
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Bastounis E, Álvarez-González B, del Álamo JC, Lasheras JC, Firtel RA. Cooperative cell motility during tandem locomotion of amoeboid cells. Mol Biol Cell 2016; 27:1262-71. [PMID: 26912787 PMCID: PMC4831880 DOI: 10.1091/mbc.e15-12-0836] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 02/08/2016] [Indexed: 01/11/2023] Open
Abstract
Tandem pairs of Dictyostelium cells migrate synchronously with an ~54-s time delay between the formation of their frontal protrusions. Each cell establishes two active adhesions, with the trailing cell reusing the location of the adhesions of the leading cell. This coordinated motility is mechanically driven and aided by cell–cell adhesions. Streams of migratory cells are initiated by the formation of tandem pairs of cells connected head to tail to which other cells subsequently adhere. The mechanisms regulating the transition from single to streaming cell migration remain elusive, although several molecules have been suggested to be involved. In this work, we investigate the mechanics of the locomotion of Dictyostelium tandem pairs by analyzing the spatiotemporal evolution of their traction adhesions (TAs). We find that in migrating wild-type tandem pairs, each cell exerts traction forces on stationary sites (∼80% of the time), and the trailing cell reuses the location of the TAs of the leading cell. Both leading and trailing cells form contractile dipoles and synchronize the formation of new frontal TAs with ∼54-s time delay. Cells not expressing the lectin discoidin I or moving on discoidin I–coated substrata form fewer tandems, but the trailing cell still reuses the locations of the TAs of the leading cell, suggesting that discoidin I is not responsible for a possible chemically driven synchronization process. The migration dynamics of the tandems indicate that their TAs’ reuse results from the mechanical synchronization of the leading and trailing cells’ protrusions and retractions (motility cycles) aided by the cell–cell adhesions.
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Affiliation(s)
- Effie Bastounis
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093-0380
| | - Begoña Álvarez-González
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA 92093-0380
| | - Juan C del Álamo
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA 92093-0380
| | - Juan C Lasheras
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA 92093-0380 Department of Bioengineering, Jacobs School of Engineering, University of California, San Diego, La Jolla, CA 92093-0380
| | - Richard A Firtel
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093-0380
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Mohamed W, Ray S, Brazill D, Baskar R. Absence of catalytic domain in a putative protein kinase C (PkcA) suppresses tip dominance in Dictyostelium discoideum. Dev Biol 2015; 405:10-20. [PMID: 26183108 DOI: 10.1016/j.ydbio.2015.05.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Revised: 04/06/2015] [Accepted: 05/28/2015] [Indexed: 12/22/2022]
Abstract
A number of organisms possess several isoforms of protein kinase C but little is known about the significance of any specific isoform during embryogenesis and development. To address this we characterized a PKC ortholog (PkcA; DDB_G0288147) in Dictyostelium discoideum. pkcA expression switches from prestalk in mound to prespore in slug, indicating a dynamic expression pattern. Mutants lacking the catalytic domain of PkcA (pkcA(-)) did not exhibit tip dominance. A striking phenotype of pkcA- was the formation of an aggregate with a central hollow, and aggregates later fragmented to form small mounds, each becoming a fruiting body. Optical density wave patterns of cAMP in the late aggregates showed several cAMP wave generation centers. We attribute these defects in pkcA(-) to impaired cAMP signaling, altered cell motility and decreased expression of the cell adhesion molecules - CadA and CsaA. pkcA(-) slugs showed ectopic expression of ecmA in the prespore region. Further, the use of a PKC-specific inhibitor, GF109203X that inhibits the activity of catalytic domain phenocopied pkcA(-).
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Affiliation(s)
- Wasima Mohamed
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - Sibnath Ray
- Department of Biological Sciences, Center for Translational and Basic Research, Hunter College and The Graduate Center of the City University of New York, New York, NY 10065, USA
| | - Derrick Brazill
- Department of Biological Sciences, Center for Translational and Basic Research, Hunter College and The Graduate Center of the City University of New York, New York, NY 10065, USA
| | - Ramamurthy Baskar
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India.
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Root of Dictyostelia based on 213 universal proteins. Mol Phylogenet Evol 2015; 92:53-62. [PMID: 26048704 DOI: 10.1016/j.ympev.2015.05.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 05/18/2015] [Accepted: 05/19/2015] [Indexed: 01/03/2023]
Abstract
Dictyostelia are common soil microbes that can aggregate when starved to form multicellular fruiting bodies, a characteristic that has also led to their long history of study and widespread use as model systems. Ribosomal RNA phylogeny of Dictyostelia identified four major divisions (Groups 1-4), none of which correspond to traditional genera. Group 1 was also tentatively identified as sister lineage to the other three Groups, although not consistently or with strong support. We tested the dictyostelid root using universal protein-coding genes identified by exhaustive comparison of six completely sequenced dictyostelid genomes, which include representatives of all four major molecular Groups. A set of 213 genes are low-copy number in all genomes, present in at least one amoebozoan outgroup taxon (Acanthamoeba castellanii or Physarum polycephalum), and phylogenetically congruent. Phylogenetic analysis of a concatenation of the deduced protein sequences produces a single topology dividing Dictyostelia into two major divisions: Groups 1+2 and Groups 3+4. All clades in the tree are fully supported by maximum likelihood and Bayesian inference, and all alternative roots are unambiguously rejected by the approximately unbiased (AU) test. The 1+2, 3+4 root is also fully supported even after deleting clusters with strong individual support for this root, or concatenating all clusters with low support for alternative roots. The 213 putatively ancestral amoebozoan proteins encode a wide variety of functions including 21 KOG categories out of a total of 25. These comprehensive analyses and consistent results indicate that it is time for full taxonomic revision of Dictyostelia, which will also enable more effective exploitation of its unique potential as an evolutionary model system.
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Assembly of the TgrB1-TgrC1 cell adhesion complex during Dictyostelium discoideum development. Biochem J 2014; 459:241-9. [PMID: 24490801 DOI: 10.1042/bj20131594] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
In Dictyostelium discoideum, TgrB1 and TgrC1 are partners of a heterophilic cell-adhesion system. To investigate its assembly process, the split GFP complementation assay was used to track the oligomeric status of both proteins. The ability of TgrC1 to form cis-homodimers spontaneously was demonstrated by fluorescence complementation studies and confirmed by chemical cross-linking. In contrast, TgrB1 failed to form cis-homodimers in the absence of TgrC1. Treatment of cell aggregates with antibodies against TgrB1 or TgrC1 did not affect TgrC1 dimerization, but inhibited TgrB1 dimer formation, suggesting that TgrB1 cis-homodimerization is dependent on trans-interaction with TgrC1. When TgrB1 and TgrC1 conjugated with the complementary halves of GFP were co-expressed in cells, cis-heterodimers were not detected. However, weak FRET signals were detected in cells expressing TgrB1-RFP and TgrC1-GFP, suggesting that TgrB1 dimers and TgrC1 dimers were arranged juxtapose to each other in the adhesion complex. The results of the present study suggest that the assembly process is initiated upon trans-interaction of monomeric TgrB1 with TgrC1 homodimers on adjacent cells, which triggers the formation of TgrB1 dimers. The homodimerization of TgrB1 in turn induces the clustering of TgrB1 and TgrC1, and the coalescence of TgrB1-TgrC1 clusters results in the formation of large adhesion complexes.
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Garcia T, Brunnet LG, De Monte S. Differential adhesion between moving particles as a mechanism for the evolution of social groups. PLoS Comput Biol 2014; 10:e1003482. [PMID: 24586133 PMCID: PMC3937110 DOI: 10.1371/journal.pcbi.1003482] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2013] [Accepted: 12/13/2013] [Indexed: 11/18/2022] Open
Abstract
The evolutionary stability of cooperative traits, that are beneficial to other individuals but costly to their carrier, is considered possible only through the establishment of a sufficient degree of assortment between cooperators. Chimeric microbial populations, characterized by simple interactions between unrelated individuals, restrain the applicability of standard mechanisms generating such assortment, in particular when cells disperse between successive reproductive events such as happens in Dicyostelids and Myxobacteria. In this paper, we address the evolutionary dynamics of a costly trait that enhances attachment to others as well as group cohesion. By modeling cells as self-propelled particles moving on a plane according to local interaction forces and undergoing cycles of aggregation, reproduction and dispersal, we show that blind differential adhesion provides a basis for assortment in the process of group formation. When reproductive performance depends on the social context of players, evolution by natural selection can lead to the success of the social trait, and to the concomitant emergence of sizeable groups. We point out the conditions on the microscopic properties of motion and interaction that make such evolutionary outcome possible, stressing that the advent of sociality by differential adhesion is restricted to specific ecological contexts. Moreover, we show that the aggregation process naturally implies the existence of non-aggregated particles, and highlight their crucial evolutionary role despite being largely neglected in theoretical models for the evolution of sociality. Although pervasive in the living world, collective behavior is a puzzle for evolutionary biology. The genetic traits that sustain it are costly for their carriers and make them vulnerable to the exploitation of asocial “free-riders” that benefit from the group without contributing to its cohesion. This paradox has spawned an extensive literature mainly concerned with elaborate cooperative behaviors that might be inoperant for simple biological entities such as microbes. We model successive life cycles of aggregation, reproduction and dispersal in a biological population combining a statistical physics approach to mimic the group formation process and an evolutionary game theory approach to account for the conflict between individual competition and collective success. Our results show a parsimonious way to the advent of sociality based on differential physical adhesion in organisms deprived of complex cognitive abilities. We also stress the key role of ungrouped individuals and specify the conditions on motion properties that make sociality possible. In detailing a mechanism akin to promote social behavior in microbes in the absence of genealogical relatedness, our work might shed light on both the maintenance of facultative multicellular lifestyles and the evolutionary origins of multicellularity.
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Affiliation(s)
- Thomas Garcia
- CNRS UMR 7625 Écologie et Évolution, École Normale Supérieure, Paris, France
- CNRS UMR 7625 Écologie et Évolution, Université Pierre et Marie Curie-Paris 6, Paris, France
- * E-mail:
| | | | - Silvia De Monte
- CNRS UMR 8197 INSERM U1024, Institut de Biologie de l'École Normale Supérieure (IBENS), Paris, France
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TgrC1 mediates cell–cell adhesion by interacting with TgrB1 via mutual IPT/TIG domains during development of Dictyostelium discoideum. Biochem J 2013; 452:259-69. [DOI: 10.1042/bj20121674] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Cell–cell adhesion plays crucial roles in cell differentiation and morphogenesis during development of Dictyostelium discoideum. The heterophilic adhesion protein TgrC1 (Tgr is transmembrane, IPT, IG, E-set, repeat protein) is expressed during cell aggregation, and disruption of the tgrC1 gene results in the arrest of development at the loose aggregate stage. We have used far-Western blotting coupled with MS to identify TgrB1 as the heterophilic binding partner of TgrC1. Co-immunoprecipitation and pull-down studies showed that TgrB1 and TgrC1 are capable of binding with each other in solution. TgrB1 and TgrC1 are encoded by a pair of adjacent genes which share a common promoter. Both TgrB1 and TgrC1 are type I transmembrane proteins, which contain three extracellular IPT/TIG (immunoglobulin, plexin, transcription factor-like/transcription factor immunoglobulin) domains. Antibodies raised against TgrB1 inhibit cell reassociation at the post-aggregation stage of development and block fruiting body formation. Ectopic expression of TgrB1 and TgrC1 driven by the actin15 promoter leads to heterotypic cell aggregation of vegetative cells. Using recombinant proteins that cover different portions of TgrB1 and TgrC1 in binding assays, we have mapped the cell-binding regions in these two proteins to Lys537–Ala783 in TgrB1 and Ile336–Val360 in TgrC1, corresponding to their respective TIG3 and TIG2 domain.
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18
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Ivanova VP, Kovaleva ZV, Anokhina VV, Krivchenko AI. The effect of a collagen tripeptide fragment (GER) on fibroblast adhesion and spreading depends on properties of an adhesive surface. ACTA ACUST UNITED AC 2013. [DOI: 10.1134/s1990519x13010057] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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19
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Schäfer E, Tarantola M, Polo E, Westendorf C, Oikawa N, Bodenschatz E, Geil B, Janshoff A. Chemotaxis of Dictyostelium discoideum: collective oscillation of cellular contacts. PLoS One 2013; 8:e54172. [PMID: 23349816 PMCID: PMC3547869 DOI: 10.1371/journal.pone.0054172] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Accepted: 12/07/2012] [Indexed: 01/11/2023] Open
Abstract
Chemotactic responses of Dictyostelium discoideum cells to periodic self-generated signals of extracellular cAMP comprise a large number of intricate morphological changes on different length scales. Here, we scrutinized chemotaxis of single Dictyostelium discoideum cells under conditions of starvation using a variety of optical, electrical and acoustic methods. Amebas were seeded on gold electrodes displaying impedance oscillations that were simultaneously analyzed by optical video microscopy to relate synchronous changes in cell density, morphology, and distance from the surface to the transient impedance signal. We found that starved amebas periodically reduce their overall distance from the surface producing a larger impedance and higher total fluorescence intensity in total internal reflection fluorescence microscopy. Therefore, we propose that the dominant sources of the observed impedance oscillations observed on electric cell-substrate impedance sensing electrodes are periodic changes of the overall cell-substrate distance of a cell. These synchronous changes of the cell-electrode distance were also observed in the oscillating signal of acoustic resonators covered with amebas. We also found that periodic cell-cell aggregation into transient clusters correlates with changes in the cell-substrate distance and might also contribute to the impedance signal. It turned out that cell-cell contacts as well as cell-substrate contacts form synchronously during chemotaxis of Dictyostelium discoideum cells.
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Affiliation(s)
- Edith Schäfer
- Institute of Physical Chemistry, Georg-August-University Göttingen, Göttingen, Germany
| | - Marco Tarantola
- Laboratory for Fluid Dynamics, Pattern Formation and Biocomplexity (LFPB), Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany
| | - Elena Polo
- Institute of Physical Chemistry, Georg-August-University Göttingen, Göttingen, Germany
| | - Christian Westendorf
- Laboratory for Fluid Dynamics, Pattern Formation and Biocomplexity (LFPB), Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany
| | - Noriko Oikawa
- Laboratory for Fluid Dynamics, Pattern Formation and Biocomplexity (LFPB), Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany
| | - Eberhard Bodenschatz
- Laboratory for Fluid Dynamics, Pattern Formation and Biocomplexity (LFPB), Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany
- Institute of Nonlinear Dynamics, Georg-August-University Göttingen, Göttingen, Germany
| | - Burkhard Geil
- Institute of Physical Chemistry, Georg-August-University Göttingen, Göttingen, Germany
| | - Andreas Janshoff
- Institute of Physical Chemistry, Georg-August-University Göttingen, Göttingen, Germany
- * E-mail:
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20
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Parfrey LW, Lahr DJG. Multicellularity arose several times in the evolution of eukaryotes (Response to DOI 10.1002/bies.201100187). Bioessays 2013; 35:339-47. [DOI: 10.1002/bies.201200143] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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21
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Evolution and diversity of dictyostelid social amoebae. Protist 2011; 163:327-43. [PMID: 22209334 DOI: 10.1016/j.protis.2011.09.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Revised: 09/08/2011] [Accepted: 09/18/2011] [Indexed: 11/23/2022]
Abstract
Dictyostelid social amoebae are a large and ancient group of soil microbes with an unusual multicellular stage in their life cycle. Taxonomically, they belong to the eukaryotic supergroup Amoebozoa, the sister group to Opisthokonta (animals + fungi). Roughly half of the ~150 known dictyostelid species were discovered during the last five years and probably many more remain to be found. The traditional classification system of Dictyostelia was completely overturned by cladistic analyses and molecular phylogenies of the past six years. As a result, it now appears that, instead of three major divisions there are eight, none of which correspond to traditional higher-level taxa. In addition to the widely studied Dictyostelium discoideum, there are now efforts to develop model organisms and complete genome sequences for each major group. Thus Dictyostelia is becoming an excellent model for both practical, medically related research and for studying basic principles in cell-cell communication and developmental evolution. In this review we summarize the latest information about their life cycle, taxonomy, evolutionary history, genome projects and practical importance.
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Zhao ZM, Reynolds AB, Gaucher EA. The evolutionary history of the catenin gene family during metazoan evolution. BMC Evol Biol 2011; 11:198. [PMID: 21740572 PMCID: PMC3141441 DOI: 10.1186/1471-2148-11-198] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Accepted: 07/08/2011] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Catenin is a gene family composed of three subfamilies; p120, beta and alpha. Beta and p120 are homologous subfamilies based on sequence and structural comparisons, and are members of the armadillo repeat protein superfamily. Alpha does not appear to be homologous to either beta or p120 based on the lack of sequence and structural similarity, and the alpha subfamily belongs to the vinculin superfamily. Catenins link the transmembrane protein cadherin to the cytoskeleton and thus function in cell-cell adhesion. To date, only the beta subfamily has been evolutionarily analyzed and experimentally studied for its functions in signaling pathways, development and human diseases such as cancer. We present a detailed evolutionary study of the whole catenin family to provide a better understanding of how this family has evolved in metazoans, and by extension, the evolution of cell-cell adhesion. RESULTS All three catenin subfamilies have been detected in metazoans used in the present study by searching public databases and applying species-specific BLAST searches. Two monophyletic clades are formed between beta and p120 subfamilies using Bayesian phylogenetic inference. Phylogenetic analyses also reveal an array of duplication events throughout metazoan history. Furthermore, numerous annotation issues for the catenin family have been detected by our computational analyses. CONCLUSIONS Delta2/ARVCF catenin in the p120 subfamily, beta catenin in the beta subfamily, and alpha2 catenin in the alpha subfamily are present in all metazoans analyzed. This implies that the last common ancestor of metazoans had these three catenin subfamilies. However, not all members within each subfamily were detected in all metazoan species. Each subfamily has undergone duplications at different levels (species-specific, subphylum-specific or phylum-specific) and to different extents (in the case of the number of homologs). Extensive annotation problems have been resolved in each of the three catenin subfamilies. This resolution provides a more coherent description of catenin evolution.
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Affiliation(s)
- Zi-Ming Zhao
- School of Biology, Georgia Institute of Technology, Atlanta, GA 30332, USA
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23
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Siu CH, Sriskanthadevan S, Wang J, Hou L, Chen G, Xu X, Thomson A, Yang C. Regulation of spatiotemporal expression of cell-cell adhesion molecules during development of Dictyostelium discoideum. Dev Growth Differ 2011; 53:518-27. [DOI: 10.1111/j.1440-169x.2011.01267.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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24
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Sriskanthadevan S, Zhu Y, Manoharan K, Yang C, Siu CH. The cell adhesion molecule DdCAD-1 regulates morphogenesis through differential spatiotemporal expression in Dictyostelium discoideum. Development 2011; 138:2487-97. [PMID: 21561987 DOI: 10.1242/dev.060129] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
During development of Dictyostelium, multiple cell types are formed and undergo a coordinated series of morphogenetic movements guided by their adhesive properties and other cellular factors. DdCAD-1 is a unique homophilic cell adhesion molecule encoded by the cadA gene. It is synthesized in the cytoplasm and transported to the plasma membrane by contractile vacuoles. In chimeras developed on soil plates, DdCAD-1-expressing cells showed greater propensity to develop into spores than did cadA-null cells. When development was performed on non-nutrient agar, wild-type cells sorted from the cadA-null cells and moved to the anterior zone. They differentiated mostly into stalk cells and eventually died, whereas the cadA-null cells survived as spores. To assess the role of DdCAD-1 in this novel behavior of wild-type and mutant cells, cadA-null cells were rescued by the ectopic expression of DdCAD-1-GFP. Morphological studies have revealed major spatiotemporal changes in the subcellular distribution of DdCAD-1 during development. Whereas DdCAD-1 became internalized in most cells in the post-aggregation stages, it was prominent in the contact regions of anterior cells. Cell sorting was also restored in cadA(-) slugs by exogenous recombinant DdCAD-1. Remarkably, DdCAD-1 remained on the surface of anterior cells, whereas it was internalized in the posterior cells. Additionally, DdCAD-1-expressing cells migrated slower than cadA(-) cells and sorted to the anterior region of chimeric slugs. These results show that DdCAD-1 influences the sorting behavior of cells in slugs by its differential distribution on the prestalk and prespore cells.
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Affiliation(s)
- Shrivani Sriskanthadevan
- The Banting and Best Department of Medical Research, University of Toronto, Toronto, ON M5S 1A8, Canada
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25
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Mujumdar N, Inouye K, Nanjundiah V. The trishanku gene and terminal morphogenesis in Dictyostelium discoideum. Evol Dev 2010; 11:697-709. [PMID: 19878291 DOI: 10.1111/j.1525-142x.2009.00377.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Multicellular development in the social amoeba Dictyostelium discoideum is triggered by starvation. It involves a series of morphogenetic movements, among them being the rising of the spore mass to the tip of the stalk. The process requires precise coordination between two distinct cell types-presumptive (pre-) spore cells and presumptive (pre-) stalk cells. Trishanku (triA) is a gene expressed in prespore cells that is required for normal morphogenesis. The triA(-) mutant shows pleiotropic effects that include an inability of the spore mass to go all the way to the top. We have examined the cellular behavior required for the normal ascent of the spore mass. Grafting and mixing experiments carried out with tissue fragments and cells show that the upper cup, a tissue that derives from prestalk cells and anterior-like cells (ALCs), does not develop properly in a triA(-) background. A mutant upper cup is unable to lift the spore mass to the top of the fruiting body, likely due to defective intercellular adhesion. If wild-type upper cup function is provided by prestalk and ALCs, trishanku spores ascend all the way. Conversely, Ax2 spores fail to do so in chimeras in which the upper cup is largely made up of mutant cells. Besides proving that under these conditions the wild-type phenotype of the upper cup is necessary and sufficient for terminal morphogenesis in D. discoideum, this study provides novel insights into developmental and evolutionary aspects of morphogenesis in general. Genes that are active exclusively in one cell type can elicit behavior in a second cell type that enhances the reproductive fitness of the first cell type, thereby showing that morphogenesis is a cooperative process.
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Affiliation(s)
- Nameeta Mujumdar
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore 560012, India.
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26
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Swarbrick JD, Cubeddu L, Ball GE, Curmi PMG, Gooley AA, Williams KL, Mabbutt BC. NMR assignment of prespore specific antigen--a cell surface adhesion glycoprotein from Dictyostelium discoideum. BIOMOLECULAR NMR ASSIGNMENTS 2009; 3:1-3. [PMID: 19636933 DOI: 10.1007/s12104-008-9126-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2008] [Accepted: 10/21/2008] [Indexed: 05/28/2023]
Abstract
Presopore-specific antigen (PsA) is a cell surface glycoprotein of the cellular slime mould Dictyostelium discoidum implicated in cell adhesion. The (15)N, (13)C and (1)H chemical shift assignments of PsA were determined from multidimensional, multinuclear NMR experiments. Resonance assignments have been made for both the N-terminal globular domain and its attached O-glycosylated PTVT linker motif.
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Affiliation(s)
- James D Swarbrick
- Department of Chemistry & Biomolecular Sciences, Macquarie University, Sydney, NSW, Australia.
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27
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Abstract
Wnt proteins mediate the transduction of at least three major signaling pathways that play central roles in many early and late developmental decisions. They control diverse cellular behaviors, such as cell fate decisions, proliferation, and migration, and are involved in many important embryological events, including axis specification, gastrulation, and limb, heart, or neural development. The three major Wnt pathways are activated by ligands, the Wnts, which clearly belong to the same gene family. However, their signal is then mediated by three separate sets of extracellular, cytoplasmic, and nuclear components that are pathway-specific and that distinguish each of them. Homologs of the Wnt genes and of the Wnt pathways components have been discovered in many eukaryotic model systems and functional investigations have been carried out for most of them. This review extracts available data on the Wnt pathways, from the protist Dictyostelium discoideum to humans, and provides from an evolutionary prospective the overall molecular and functional conservation of the three Wnt pathways and their activators throughout the eukaryotic superkingdom.
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28
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Abstract
Although Wnt signaling is ubiquitous within the animal phylogenetic group, it is unclear how it evolved. Genes related to the components of Wnt pathway are found in other eukaryotes and one of the most studied of these non-metazoan organisms is the social amoeba Dictyostelium discoideum. This organism contains the enzyme GSK-3 and a beta -catenin homolog, Aardvark (Aar). Both are required to regulate pattern formation during multi-cellular stages of Dictyostelium development. Aar is also required for formation of adherens junctions, as seen in animals. Finally, analysis of the completed Dictyostelium genome shows there to be 16 Frizzled (Fz) gene homologs. This chapter discusses Dictyostelium development and the role of these proteins.
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Affiliation(s)
- Adrian J Harwood
- Cardiff School of Biosciences, Cardiff University, Cardiff, Wales, UK
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29
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Kim J, Heslop-Harrison P, Postlethwaite I, Bates DG. Stochastic noise and synchronisation during dictyostelium aggregation make cAMP oscillations robust. PLoS Comput Biol 2007; 3:e218. [PMID: 17997595 PMCID: PMC2065893 DOI: 10.1371/journal.pcbi.0030218] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Accepted: 09/25/2007] [Indexed: 11/18/2022] Open
Abstract
Stable and robust oscillations in the concentration of adenosine 3′, 5′-cyclic monophosphate (cAMP) are observed during the aggregation phase of starvation-induced development in Dictyostelium discoideum. In this paper we use mathematical modelling together with ideas from robust control theory to identify two factors which appear to make crucial contributions to ensuring the robustness of these oscillations. Firstly, we show that stochastic fluctuations in the molecular interactions play an important role in preserving stable oscillations in the face of variations in the kinetics of the intracellular network. Secondly, we show that synchronisation of the aggregating cells through the diffusion of extracellular cAMP is a key factor in ensuring robustness of the oscillatory waves of cAMP observed in Dictyostelium cell cultures to cell-to-cell variations. A striking and quite general implication of the results is that the robustness analysis of models of oscillating biomolecular networks (circadian clocks, Ca2+ oscillations, etc.) can only be done reliably by using stochastic simulations, even in the case where molecular concentrations are very high. The molecular network, which underlies the oscillations in the concentration of adenosine 3′, 5′-cyclic monophosphate (cAMP) during the aggregation phase of starvation-induced development in Dictyostelium discoideum, achieves remarkable levels of robust performance in the face of environmental variations and cellular heterogeneity. However, the reasons for this robustness remain poorly understood. Tools and concepts from the field of control engineering provide powerful methods for uncovering the mechanisms underlying the robustness of these types of biological systems. Using such methods, two important factors contributing to the robustness of cAMP oscillations in Dictyostelium are revealed. First, stochastic fluctuations in the molecular interactions of the intracellular network, arising from random or directional noise and biological sources, play an important role in preserving stable oscillations in the face of variations in the kinetics of the network. Second, synchronisation of the aggregating cells through the diffusion of extracellular cAMP appears to be a key factor in ensuring robustness to cell-to-cell variations of the oscillatory waves of cAMP observed in Dictyostelium cell cultures. The conclusions have important general implications for the robustness of oscillating biomolecular networks (whether seen at organism, cell, or intracellular levels and including circadian clocks or Ca2+ oscillations, etc.), and suggest that such analysis can be conducted more reliably by using models including stochastic simulations, even in the case where molecular concentrations are very high.
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Affiliation(s)
- Jongrae Kim
- Control and Instrumentation Group, Department of Engineering, University of Leicester, Leicester, United Kingdom.
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30
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Barth C, Le P, Fisher PR. Mitochondrial biology and disease in Dictyostelium. INTERNATIONAL REVIEW OF CYTOLOGY 2007; 263:207-52. [PMID: 17725968 DOI: 10.1016/s0074-7696(07)63005-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The cellular slime mold Dictyostelium discoideum has become an increasingly useful model for the study of mitochondrial biology and disease. Dictyostelium is an amoebazoan, a sister clade to the animal and fungal lineages. The mitochondrial biology of Dictyostelium exhibits some features which are unique, others which are common to all eukaryotes, and still others that are otherwise found only in the plant or the animal lineages. The AT-rich mitochondrial genome of Dictyostelium is larger than its mammalian counterpart and contains 56kb (compared to 17kb in mammals) encoding tRNAs, rRNAs, and 33 polypeptides (compared to 13 in mammals). It produces a single primary transcript that is cotranscriptionally processed into multiple monocistronic, dicistronic, and tricistronic mRNAs, tRNAs, and rRNAs. The mitochondrial fission mechanism employed by Dictyostelium involves both the extramitochondrial dynamin-based system used by plant, animal, and fungal mitochondria and the ancient FtsZ-based intramitochondrial fission process inherited from the bacterial ancestor. The mitochondrial protein-import apparatus is homologous to that of other eukaryote, and mitochondria in Dictyostelium play an important role in the programmed cell death pathways. Mitochondrial disease in Dictyostelium has been created both by targeted gene disruptions and by antisense RNA and RNAi inhibition of expression of essential nucleus-encoded mitochondrial proteins. This has revealed a regular pattern of aberrant mitochondrial disease phenotypes caused not by ATP insufficiency per se, but by chronic activation of the universal eukaryotic energy-sensing protein kinase AMPK. This novel insight into the cytopathological mechanisms of mitochondrial dysfunction suggests new possibilities for therapeutic intervention in mitochondrial and neurodegenerative diseases.
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Affiliation(s)
- Christian Barth
- Department of Microbiology, La Trobe University, Melbourne VIC 3086, Australia
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31
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Rai M, Xiong Y, Singleton CK. Disruption of the ifkA and ifkB genes results in altered cell adhesion, morphological defects and a propensity to form pre-stalk O cells during development of Dictyostelium. Differentiation 2006; 74:583-95. [PMID: 17177855 DOI: 10.1111/j.1432-0436.2006.00085.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
IfkA and ifkB are two GCN2-like genes present in Dictyostelium. Disruption of either gene alone results in subtle developmental defects. However, disruption of ifkA and ifkB within the same strain results in severe morphological and patterning defects in the developing double null cells. The mutant cells aggregate in streams that give tightly clumped mounds. Fingers form from the mounds but remain attached to one another, especially at their bases. The fingers culminate to give fused and entangled structures lacking proper stalk but containing some spores. The morphological defects are consistent with an enhanced cell-cell and cell-substrate adhesiveness of the developing double null cells, which may result in inappropriate cell contacts and altered cell motility and sorting properties. In ifkA/ifkB nulls, cell type proportioning and patterning is altered in favor of ALC/pstO cell types. The bias toward the ALC/pstO cell types may be due, in part, to the nuclear localization of the transcription factor STATc in growing ifkA/ifkB null cells. STATc normally becomes localized to the nucleus during finger formation and only within the pre-stalk O zone. The precocious nuclear localization seen in the mutant cells may predispose the cells to a ALC/pstO cell fate. The findings indicate that IfkA and IfkB have redundant functions in Dictyostelium morphogenesis that involve maintaining proper cell-cell and cell-substrate adhesion and the equilibrium between different cell types for proper spatial patterning.
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Affiliation(s)
- Meena Rai
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235-1634, USA
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32
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Lin Z, Sriskanthadevan S, Huang H, Siu CH, Yang D. Solution structures of the adhesion molecule DdCAD-1 reveal new insights into Ca2+-dependent cell-cell adhesion. Nat Struct Mol Biol 2006; 13:1016-22. [PMID: 17057715 DOI: 10.1038/nsmb1162] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2006] [Accepted: 10/03/2006] [Indexed: 02/06/2023]
Abstract
DdCAD-1 is a novel Ca(2+)-dependent cell adhesion molecule that lacks a hydrophobic signal peptide and a transmembrane domain. DdCAD-1 is expressed by the social amoeba Dictyostelium discoideum at the onset of development. It is synthesized as a soluble protein and then transported to the plasma membrane by contractile vacuoles. Here we describe the novel features of the solution structures of Ca(2+)-free and Ca(2+)-bound monomeric DdCAD-1. DdCAD-1 contains two beta-sandwich domains, belonging to the betagamma-crystallin and immunoglobulin fold classes, respectively. Whereas the N-terminal domain has a major role in homophilic binding, the C-terminal domain tethers the protein to the cell membrane. From structural and mutational analyses, we propose a model for the Ca(2+)-bound DdCAD-1 dimer as a basis for understanding DdCAD-1-mediated cell-cell adhesion at the molecular level. Our results provide new insights into Ca(2+)-dependent mechanisms for cell-cell adhesion.
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Affiliation(s)
- Zhi Lin
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543
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33
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Secko DM, Siu CH, Spiegelman GB, Weeks G. An activated Ras protein alters cell adhesion by dephosphorylating Dictyostelium DdCAD-1. MICROBIOLOGY-SGM 2006; 152:1497-1505. [PMID: 16622066 DOI: 10.1099/mic.0.28709-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
RasG-regulated signal transduction has been linked to a variety of growth-specific processes and appears to also play a role in the early development of Dictyostelium discoideum. In an attempt to uncover some of the molecular components involved in Ras-mediated signalling, several proteins have been described previously, including the cell adhesion molecule DdCAD-1, whose phosphorylation state was affected by the expression of the constitutively activated RasG, RasG(G12T). Here it has been shown that a cadA null strain lacks the phosphoproteins that were tentatively identified as DdCAD-1, confirming its previous designation. Further investigation revealed that cells expressing RasG(G12T) exhibited increased cell-cell cohesion, concomitant with reduced levels of DdCAD-1 phosphorylation. This increased cohesion was DdCAD-1-dependent and was correlated with increased localization of DdCAD-1 at the cell surface. DdCAD-1 phosphorylation was also found to decrease during Dictyostelium aggregation. These results revealed a possible role for protein phosphorylation in regulating DdCAD-1-mediated cell adhesion during early development. In addition, the levels of DdCAD-1 protein were substantially reduced in a rasG null cell line. These results indicate that RasG affects both the expression and dephosphorylation of DdCAD-1 during early development.
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Affiliation(s)
- David M Secko
- Department of Microbiology and Immunology, University of British Columbia, Life Sciences Centre, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z4, Canada
| | - Chi-Hung Siu
- Banting and Best Department of Medical Research, and Department of Biochemistry, University of Toronto, Toronto, Ontario M5G 1L6, Canada
| | - George B Spiegelman
- Department of Microbiology and Immunology, University of British Columbia, Life Sciences Centre, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z4, Canada
| | - Gerald Weeks
- Department of Microbiology and Immunology, University of British Columbia, Life Sciences Centre, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z4, Canada
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34
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Muramoto T, Urushihara H. Small GTPase RacF2 affects sexual cell fusion and asexual development in Dictyostelium discoideum through the regulation of cell adhesion. Dev Growth Differ 2006; 48:199-208. [PMID: 16573737 DOI: 10.1111/j.1440-169x.2006.00857.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cells of Dictyostelium discoideum become sexually mature when submerged and in darkness, and fuse with opposite mating-type cells as gametes. The gene for a Rho GTPase, RacF2, is one of the extremely gamete-enriched genes (>100-fold) identified by us previously. Here, we isolated knockout, overexpression, constitutively active and dominant negative mutants of RacF2, and analyzed their phenotypes. These mutants showed anomalies in the extent of sexual cell fusion and asexual development as well as in EDTA-sensitive cell-cell adhesion. It is suggested that RacF2 controls the process of sexual and asexual development through the regulation of cellular adhesiveness. An analysis of the expression of all 18 rac family genes by real-time polymerase chain reaction revealed that four additional genes, rac1b, rac1c, racF1 and racG, were induced during maturation, suggesting their possible involvement in sexual cell interactions.
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Affiliation(s)
- Tetsuya Muramoto
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan.
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35
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Coates JC, Laplaze L, Haseloff J. Armadillo-related proteins promote lateral root development in Arabidopsis. Proc Natl Acad Sci U S A 2006; 103:1621-6. [PMID: 16434475 PMCID: PMC1360535 DOI: 10.1073/pnas.0507575103] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Armadillo/beta-catenin and related proteins have important functions during animal and Dictyostelium development, regulating cell differentiation, proliferation, and adhesion. Armadillo-repeat-containing proteins also exist in plants, but the majority have unknown roles. The Arabidopsis genes that show greatest sequence homology to Armadillo/beta-catenin are called ARABIDILLO-1 and -2. Here, we demonstrate that ARABIDILLO-1 and -2 promote lateral root development. arabidillo-1/-2 mutants form fewer lateral roots, and ARABIDILLO-1-overexpressing lines produce more lateral roots than wild-type seedlings. ARABIDILLO-yellow fluorescent protein fusions are nuclear. ARABIDILLO proteins contain an F-box motif, and thus may target other proteins for proteasomal degradation. Overexpression of ARABIDILLO-1 protein fragments, including F-box fragments, in wild-type seedlings reduces lateral root formation to the level of the arabidillo-1/-2 mutant. We have shown that plant beta-catenin-related proteins regulate root development. We suggest that ARABIDILLO proteins may target an inhibitor of lateral root development for degradation and propose that Arabidopsis beta-catenin-related proteins define a previously uncharacterized pathway that promotes root branching.
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Affiliation(s)
- Juliet C Coates
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.
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36
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Williams JG, Noegel AA, Eichinger L. Manifestations of multicellularity: Dictyostelium reports in. Trends Genet 2005; 21:392-8. [PMID: 15975432 DOI: 10.1016/j.tig.2005.05.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2004] [Revised: 02/08/2005] [Accepted: 05/03/2005] [Indexed: 12/21/2022]
Abstract
The recent release of the Dictyostelium genome sequence is important because Dictyostelium has become a much-favoured model system for cell and developmental biologists. The sequence has revealed a remarkably high total number of approximately 12 500 genes, only a thousand fewer than are encoded by Drosophila. Previous protein-sequence comparisons suggested that Dictyostelium is evolutionarily closer to animals and fungi than to plants, and the global protein sequence comparison, now made possible by the genome sequence, confirms this. This review focuses on several classes of proteins that are shared by Dictyostelium and animals: a highly sophisticated array of microfilament components, a large family of G-protein-coupled receptors and a diverse set of SH2 domain-containing proteins. The presence of these proteins strengthens the case for a relatively close relationship with animals and extends the range of problems that can be addressed using Dictyostelium as a model organism.
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Affiliation(s)
- Jeffrey G Williams
- School of Life Sciences, University of Dundee, MSI/WTB Complex, Dow Street, Dundee DD1 5EH. Scotland, UK.
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37
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Fache S, Dalous J, Engelund M, Hansen C, Chamaraux F, Fourcade B, Satre M, Devreotes P, Bruckert F. Calcium mobilization stimulatesDictyostelium discoideumshear-flow-induced cell motility. J Cell Sci 2005; 118:3445-57. [PMID: 16079287 DOI: 10.1242/jcs.02461] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Application of hydrodynamic mild shear stress to adherent Dictyostelium discoideum vegetative cells triggers active actin cytoskeleton remodeling resulting in net cell movement along the flow. The average cell speed is strongly stimulated by external calcium (Ca2+, K50%=22 μM), but the directionality of the movement is almost unaffected. This calcium concentration is ten times higher than the one promoting cell adhesion to glass surfaces (K50%=2 μM). Addition of the calcium chelator EGTA or the Ca2+-channel blocker gadolinium (Gd3+) transiently stops cell movement. Monitoring the evolution of cell-surface contact area with time reveals that calcium stimulates cell speed by increasing the amplitude of both protrusion and retraction events at the cell edge, but not the frequency. As a consequence, with saturating external calcium concentrations, cells are sensitive to very low shear forces (20 pN; σ=0.1 Pa). Moreover, a null-mutant lacking the unique Gβ subunit does not respond to external Ca2+ changes (K50%>1000 μM), although the directionality of the movement is comparable with that of wild-type cells. Furthermore, cells lacking the inositol 1,4,5-trisphosphate receptor (IP3-receptor) exhibit a markedly reduced Ca2+ sensitivity. Thus, calcium release from internal stores and calcium entry through the plasma membrane modulate cell speed in response to shear stress.
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Affiliation(s)
- Sébastien Fache
- Structures et Propriétés des Architectures Moléculaires (UMR 5919 CNRS), Département de Recherche Fondamentale sur la Matière Condensée, CEA-Grenoble, DRFMC/SI3M, 17 rue des Martyrs, 38054 Grenoble Cedex 09, France
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38
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Abstract
Cell adhesion is a basic property of animal cells, but is also present in many other eukaryotes. Did cell adhesion systems arise independently in different eukaryotic groups, or do they share common origins? Recent results show that cell adhesion proteins related to cadherin, IgG-like CAM and C-type lectin are present both in sponges, the most distant animal branch, and in eukaryote groups outside the metazoan lineage, indicating that these forms of adhesion arose prior to animal evolution. Furthermore, proteins containing features of animal adhesion systems, such as Fas-1 and thrombospondin domains, are distributed throughout the eukaryotes and function in cell adhesion.
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Affiliation(s)
- Adrian Harwood
- MRC Laboratory of Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT.
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Cohen M, Joester D, Geiger B, Addadi L. Spatial and temporal sequence of events in cell adhesion: from molecular recognition to focal adhesion assembly. Chembiochem 2005; 5:1393-9. [PMID: 15457530 DOI: 10.1002/cbic.200400162] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A new concept that attributes a pivotal role to the pericellular coat in the regulation of the early stages of cell adhesion is presented. Quick, adaptable, and transient adhesion through multiple cooperative weak interactions provides the cell with an additional level of modulation in the decision-making process that precedes the commitment to adhesion at a particular site. Hyaluronan emerges as a modulator of cell adhesion in certain cells, mediating binding or repulsion through its polyelectrolyte character, in addition to its chirality and molecular-recognition properties. The biophysical properties of hyaluronan as well as its ultrastructural organization are analyzed in relation to this proposed function.
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Affiliation(s)
- Miriam Cohen
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
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40
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Bowers-Morrow VM, Ali SO, Williams KL. Comparison of molecular mechanisms mediating cell contact phenomena in model developmental systems: an exploration of universality. Biol Rev Camb Philos Soc 2004; 79:611-42. [PMID: 15366765 DOI: 10.1017/s1464793103006389] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Are there universal molecular mechanisms associated with cell contact phenomena during metazoan ontogenesis? Comparison of adhesion systems in disparate model systems indicates the existence of unifying principles. Requirements for multicellularity are (a) the construction of three-dimensional structures involving a crucial balance between adhesiveness and motility; and (b) the establishment of integration at molecular, cellular, tissue, and organismal levels of organization. Mechanisms for (i) cell-cell and cell-substrate adhesion, (ii) cell movement, (iii) cell-cell communication, (iv) cellular responses, (v) regulation of these processes, and (vi) their integration with patterning, growth, and other developmental processes are all crucial to metazoan development, and must have been present for the emergence and radiation of Metazoa. The principal unifying themes of this review are the dynamics and regulation of cell contact phenomena. Our knowledge of the dynamic molecular mechanisms underlying cell contact phenomena remains fragmentary. Here we examine the molecular bases of cell contact phenomena using extant model developmental systems (representing a wide range of phyla) including the simplest i.e. sponges, and the eukaryotic protist Dictyostelium discoideum, the more complex Drosophila melanogaster, and vertebrate systems. We discuss cell contact phenomena in a broad developmental context. The molecular language of cell contact phenomena is complex; it involves a plethora of structurally and functionally diverse molecules, and diverse modes of intermolecular interactions mediated by protein and/or carbohydrate moieties. Reasons for this are presumably the necessity for a high degree of specificity of intermolecular interactions, the requirement for a multitude of different signals, and the apparent requirement for an increasingly large repertoire of cell contact molecules in more complex developmental systems, such as the developing vertebrate nervous system. However, comparison of molecular models for dynamic adhesion in sponges and in vertebrates indicates that, in spite of significant differences in the details of the way specific cell-cell adhesion is mediated, similar principles are involved in the mechanisms employed by members of disparate phyla. Universal requirements are likely to include (a) rapidly reversible intermolecular interactions; (b) low-affinity intermolecular interactions with fast on-off rates; (c) the compounding of multiple intermolecular interactions; (d) associated regulatory signalling systems. The apparent widespread employment of molecular mechanisms involving cadherin-like cell adhesion molecules suggests the fundamental importance of cadherin function during development, particularly in epithelial morphogenesis, cell sorting, and segregation of cells.
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41
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Powell RR, Temesvari LA. Involvement of a Rab8-like protein of Dictyostelium discoideum, Sas1, in the formation of membrane extensions, secretion and adhesion during development. MICROBIOLOGY-SGM 2004; 150:2513-2525. [PMID: 15289548 DOI: 10.1099/mic.0.27073-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Establishment of cell-cell adhesions, regulation of actin, and secretion are critical during development. Rab8-like GTPases have been shown to modulate these cellular events, suggesting an involvement in developmental processes. To further elucidate the function of Rab8-like GTPases in a developmental context, a Rab8-related protein (Sas1) of Dictyostelium discoideum was examined, the expression of which increases at the onset of development. Dictyostelium cell lines expressing inactive (N128I mutant) and constitutively active (Q74L mutant) Sas1 as green fluorescent protein (GFP)-Sas1 chimeras were generated. Cells expressing Sas1Q74L displayed numerous actin-rich membrane protrusions, increased secretion, and were unable to complete development. In particular, these cells demonstrated a reduction in adhesion as well as in the levels of a cell adhesion molecule, gp24 (DdCAD-1). In contrast, cells expressing Sas1N128I exhibited increased cell-cell adhesion and increased levels of gp24. Counting factor is a multisubunit signalling complex that is secreted in early development and controls aggregate size by negatively regulating the levels of cell adhesion molecules, including gp24. Interestingly, the Sas1Q74L mutant demonstrated increased levels of extracellular countin, a subunit of counting factor, suggesting that Sas1 may regulate trafficking of counting factor components. Together, the data suggest that Sas1 may be a key regulator of actin, adhesion and secretion during development.
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Affiliation(s)
- Rhonda R Powell
- Department of Biological Sciences, 132 Long Hall, Clemson University, Clemson, SC 29634, USA
| | - Lesly A Temesvari
- Department of Biological Sciences, 132 Long Hall, Clemson University, Clemson, SC 29634, USA
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42
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Chisholm RL, Firtel RA. Insights into morphogenesis from a simple developmental system. Nat Rev Mol Cell Biol 2004; 5:531-41. [PMID: 15232571 DOI: 10.1038/nrm1427] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Rex L Chisholm
- Cell and Molecular Biology, Center for Genetic Medicine, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, Illinois 60611, USA.
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43
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Escalante R, Moreno N, Sastre L. Dictyostelium discoideum developmentally regulated genes whose expression is dependent on MADS box transcription factor SrfA. EUKARYOTIC CELL 2004; 2:1327-35. [PMID: 14665466 PMCID: PMC326651 DOI: 10.1128/ec.2.6.1327-1335.2003] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The MADS box transcription factor SrfA is required for spore differentiation in Dictyostelium discoideum. srfA null strains form rounded spores that do not resist adverse environmental conditions. Five genes whose expression is dependent on SrfA have been isolated by differential hybridization. One of these genes, sigC, is identical to phg1b, previously characterized in mutants with altered adhesive properties and found to encode a nine-transmembrane-domain protein. This gene is transcribed into two mRNAs as the result of alternative splicing of two internal exons. The slower-migrating mRNA codes for a shorter protein that lacks the first transmembrane fragment and is not expressed in srfA null strains. The other four genes (sigA, sigB, sigD, and 45D) are expressed only during late developmental stages. In situ hybridization experiments showed that expression of sigA, sigB, and sigD is restricted to the sorus of developing structures. sigA codes for a homologue of malate dehydrogenase that converts pyruvate to malate to replenish the tricarboxylic acid cycle. sigB encodes a protein with significant similarity to the GP63 metalloproteinase of Leishmania, leishmanolysin. The sequence of SigD is highly similar to that of several spore coat proteins of D. discoideum, and it may play a role in that structure. The gene 45D codes for an RNA-binding protein homologue whose expression is also dependent on the GATA transcription factor stalky (StkA). The expression of sigB is also dependent on both SrfA and StkA. The expression of 45D, but not of sigA, sigB, sigC, and sigD, can be induced in srfA null cells by constitutive protein kinase A activation. Strains in which either sigA, sigB, or sigD is disrupted were isolated and found to form spores that are not detectably different from those of wild-type strains.
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Affiliation(s)
- Ricardo Escalante
- Instituto de Investigaciones Biomédicas, CSIC/UAM, 28029 Madrid, Spain
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44
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Tsujioka M, Yoshida K, Inouye K. Talin B is required for force transmission in morphogenesis of Dictyostelium. EMBO J 2004; 23:2216-25. [PMID: 15141168 PMCID: PMC419915 DOI: 10.1038/sj.emboj.7600238] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2003] [Accepted: 04/21/2004] [Indexed: 11/08/2022] Open
Abstract
Talin plays a key role in the assembly and stabilisation of focal adhesions, but whether it is directly involved in force transmission during morphogenesis remains to be elucidated. We show that the traction force of Dictyostelium cells mutant for one of its two talin genes talB is considerably smaller than that of wild-type cells, both in isolation and within tissues undergoing morphogenetic movement. The motility of mutant cells in tightly packed tissues in vivo or under strong resistance conditions in vitro was lower than that of wild-type cells, but their motility under low external force conditions was not impaired, indicating inefficient transmission of force in mutant cells. Antibody staining revealed that the talB gene product (talin B) exists as small units subjacent to the cell membrane at adhesion sites without forming large focal adhesion-like assemblies. The total amount of talin B on the cell membrane was larger in prestalk cells, which exert larger force than prespore cells during morphogenesis. We conclude that talin B is involved in force transmission between the cytoskeleton and cell exterior.
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Affiliation(s)
- Masatsune Tsujioka
- Department of Botany, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Kunito Yoshida
- Department of Botany, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Kei Inouye
- Department of Botany, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, Japan
- Department of Botany, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan. Tel.: +81 75 753 4130; Fax: +81 75 753 4137; E-mail:
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45
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Katoh M, Shaw C, Xu Q, Van Driessche N, Morio T, Kuwayama H, Obara S, Urushihara H, Tanaka Y, Shaulsky G. An orderly retreat: Dedifferentiation is a regulated process. Proc Natl Acad Sci U S A 2004; 101:7005-10. [PMID: 15103019 PMCID: PMC406456 DOI: 10.1073/pnas.0306983101] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Differentiation is a highly regulated process whereby cells become specialized to perform specific functions and lose the ability to perform others. In contrast, the question of whether dedifferentiation is a genetically determined process, or merely an unregulated loss of the differentiated state, has not been resolved. We show here that dedifferentiation in the social amoeba Dictyostelium discoideum relies on a sequence of events that is independent of the original developmental state and involves the coordinated expression of a specific set of genes. A defect in one of these genes, the histidine kinase dhkA, alters the kinetics of dedifferentiation and uncouples the progression of dedifferentiation events. These observations establish dedifferentiation as a genetically determined process and suggest the existence of a developmental checkpoint that ensures a return path to the undifferentiated state.
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Affiliation(s)
- Mariko Katoh
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
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46
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Kibler K, Svetz J, Nguyen TL, Shaw C, Shaulsky G. A cell-adhesion pathway regulates intercellular communication during Dictyostelium development. Dev Biol 2004; 264:506-21. [PMID: 14651934 DOI: 10.1016/j.ydbio.2003.08.025] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cell adhesion molecules play an important physical role in shaping the structure of multicellular organisms. Recent studies show that they also play a role in intracellular and intercellular signaling. We describe a cell adhesion pathway that is mediated by the intercellular communication genes comC, lagC, and lagD during Dictyostelium development. Disruptions of these genes result in strains that are unable to generate spores when developed in a pure population but are capable of sporulation when developed in chimerae with wild-type cells. In contrast, any pair-wise chimera of the three mutants fails to form spores. We postulate that the wild-type cells supply the mutant cells with a signal that partially rescues their sporulation. We also propose that the three mutants are deficient in the production of that signal, suggesting that the three genes function in one signaling pathway. In support of that notion, the mutant cells share common non-cell-autonomous prespore and prestalk-specific defects and a common pattern of developmental progression and regression. We provide transcriptional and functional evidence for a network in which comC inhibits lagC and activates lagD expression, lagC and lagD are mutually inductive, and the cell adhesion gene lagC is the terminal node in this signaling network.
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Affiliation(s)
- Kirsten Kibler
- Graduate Program in Developmental Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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47
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Takano A, Akaza Y, Hasegawa Y, Issaeva M, Masamune Y, Kodaira KI, Shinohara H, Yasukawa H. Expression of Genes Coding for Cell-Cell Adhesion Proteins in Dictyostelium discoideum Mutants that Form Small Fruiting Bodies. Microbes Environ 2004. [DOI: 10.1264/jsme2.19.76] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Akinori Takano
- Division of Bioengineering, Faculty of Engineering, Toyama University
| | - Yuya Akaza
- Division of Bioengineering, Faculty of Engineering, Toyama University
| | - Yasuna Hasegawa
- Division of Bioengineering, Faculty of Engineering, Toyama University
| | - Marina Issaeva
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Kanazawa University
| | - Yukito Masamune
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Kanazawa University
| | - Ken-ichi Kodaira
- Division of Bioengineering, Faculty of Engineering, Toyama University
| | - Hiroaki Shinohara
- Division of Bioengineering, Faculty of Engineering, Toyama University
| | - Hiro Yasukawa
- Division of Bioengineering, Faculty of Engineering, Toyama University
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48
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Kibler K, Nguyen TL, Svetz J, Van Driessche N, Ibarra M, Thompson C, Shaw C, Shaulsky G. A novel developmental mechanism in Dictyostelium revealed in a screen for communication mutants. Dev Biol 2003; 259:193-208. [PMID: 12871696 DOI: 10.1016/s0012-1606(03)00204-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We performed a screen for signaling genes by selecting mutant strains of Dictyostelium that fail to develop spores in a pure population but sporulate well in chimerae with wild type cells. We found 9 strains whose sporulation was induced up to 10 million-fold in chimerae. Most strains were also able to sporulate in chimerae with each other, but 2 pairs failed to do so, suggesting that the genes in each pair participate in the production of 1 signal. One of the pairs, comD and comB, is described in detail. Sequence analysis revealed that both genes encode putative membrane proteins. ComD is predicted to have 15 transmembrane domains, and ComB has a region of high similarity to the Rab family of small GTPases and 1 transmembrane domain. Similarities between the developmental regulation and cell-type specificity of the genes' expression, the terminal developmental morphology, and the expression pattern of cell-type specific markers in the mutants suggest that comD and comB participate in 1 signal production pathway. This idea is also supported by a high similarity between the global transcriptional profiles of the mutant strains. Differences between the mutant phenotypes late in development suggest that comD and comB participate in separate processes as well. comD has a cell-autonomous role in the specialization of a novel prespore cell type, whereas comB has a cell-autonomous role in prestalk A cell differentiation.
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Affiliation(s)
- Kirsten Kibler
- Graduate Program in Developmental Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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49
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Amaroli A, Gallus L, Passalacqua M, Falugi C, Viarengo A, Delmonte Corrado MU. Detection of cholinesterase activities and acetylcholine receptors during the developmental cycle of Dictyostelium discoideum. Eur J Protistol 2003. [DOI: 10.1078/0932-4739-00912] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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50
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Abstract
Dictyostelium genome sequencing predicts an unexpectedly large number of genes. Many are absent from yeast but present in animals and presumably support cellular abilities not found in yeast. Prominent amongst these abilities is chemotaxis, where great strides are being made in understanding how cells orient in a gradient and mobilise their cytoskeleton for movement. In multicellular development, a regulatory scheme for proportioning prespore and prestalk-O cells has emerged.
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Affiliation(s)
- Robert R Kay
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge, UK.
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