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Biondo M, Panuzzo C, Ali SM, Bozzaro S, Osella M, Bracco E, Pergolizzi B. The Dynamics of Aerotaxis in a Simple Eukaryotic Model. Front Cell Dev Biol 2021; 9:720623. [PMID: 34888305 PMCID: PMC8650612 DOI: 10.3389/fcell.2021.720623] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 10/13/2021] [Indexed: 01/09/2023] Open
Abstract
In aerobic organisms, oxygen is essential for efficient energy production, and it acts as the last acceptor of the mitochondrial electron transport chain and as regulator of gene expression. However, excessive oxygen can lead to production of deleterious reactive oxygen species. Therefore, the directed migration of single cells or cell clumps from hypoxic areas toward a region of optimal oxygen concentration, named aerotaxis, can be considered an adaptive mechanism that plays a major role in biological and pathological processes. One relevant example is the development of O2 gradients when tumors grow beyond their vascular supply, leading frequently to metastasis. In higher eukaryotic organisms, aerotaxis has only recently begun to be explored, but genetically amenable model organisms suitable to dissect this process remain an unmet need. In this regard, we sought to assess whether Dictyostelium cells, which are an established model for chemotaxis and other motility processes, could sense oxygen gradients and move directionally in their response. By assessing different physical parameters, our findings indicate that both growing and starving Dictyostelium cells under hypoxic conditions migrate directionally toward regions of higher O2 concentration. This migration is characterized by a specific pattern of cell arrangement. A thickened circular front of high cell density (corona) forms in the cell cluster and persistently moves following the oxygen gradient. Cells in the colony center, where hypoxia is more severe, are less motile and display a rounded shape. Aggregation-competent cells forming streams by chemotaxis, when confined under hypoxic conditions, undergo stream or aggregate fragmentation, giving rise to multiple small loose aggregates that coordinately move toward regions of higher O2 concentration. By testing a panel of mutants defective in chemotactic signaling, and a catalase-deficient strain, we found that the latter and the pkbR1null exhibited altered migration patterns. Our results suggest that in Dictyostelium, like in mammalian cells, an intracellular accumulation of hydrogen peroxide favors the migration toward optimal oxygen concentration. Furthermore, differently from chemotaxis, this oxygen-driven migration is a G protein-independent process.
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Affiliation(s)
- Marta Biondo
- Department of Physics, INFN, University of Turin, Turin, Italy
| | - Cristina Panuzzo
- Department of Clinical and Biological Science, University of Turin, Turin, Italy
| | - Shahzad M Ali
- Department of Clinical and Biological Science, University of Turin, Turin, Italy
| | - Salvatore Bozzaro
- Department of Clinical and Biological Science, University of Turin, Turin, Italy
| | - Matteo Osella
- Department of Physics, INFN, University of Turin, Turin, Italy
| | - Enrico Bracco
- Department of Oncology, University of Turin, Turin, Italy
| | - Barbara Pergolizzi
- Department of Clinical and Biological Science, University of Turin, Turin, Italy
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The Dictyostelium discoideum GPHR ortholog is an endoplasmic reticulum and Golgi protein with roles during development. EUKARYOTIC CELL 2014; 14:41-54. [PMID: 25380752 DOI: 10.1128/ec.00208-14] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Dictyostelium discoideum GPHR (Golgi pH regulator)/Gpr89 is a developmentally regulated transmembrane protein present on the endoplasmic reticulum (ER) and the Golgi apparatus. Transcript levels are low during growth and vary during development, reaching high levels during the aggregation and late developmental stages. The Arabidopsis ortholog was described as a G protein-coupled receptor (GPCR) for abscisic acid present at the plasma membrane, whereas the mammalian ortholog is a Golgi apparatus-associated anion channel functioning as a Golgi apparatus pH regulator. To probe its role in D. discoideum, we generated a strain lacking GPHR. The mutant had different growth characteristics than the AX2 parent strain, exhibited changes during late development, and formed abnormally shaped small slugs and fruiting bodies. An analysis of development-specific markers revealed that their expression was disturbed. The distributions of the endoplasmic reticulum and the Golgi apparatus were unaltered at the immunofluorescence level. Likewise, their functions did not appear to be impaired, since membrane proteins were properly processed and glycosylated. Also, changes in the external pH were sensed by the ER, as indicated by a pH-sensitive ER probe, as in the wild type.
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Omosigho NN, Swaminathan K, Plomann M, Müller-Taubenberger A, Noegel AA, Riyahi TY. The Dictyostelium discoideum RACK1 orthologue has roles in growth and development. Cell Commun Signal 2014; 12:37. [PMID: 24930026 PMCID: PMC4094278 DOI: 10.1186/1478-811x-12-37] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Accepted: 06/06/2014] [Indexed: 12/19/2022] Open
Abstract
Background The receptor for activated C-kinase 1 (RACK1) is a conserved protein belonging to the WD40 repeat family of proteins. It folds into a beta propeller with seven blades which allow interactions with many proteins. Thus it can serve as a scaffolding protein and have roles in several cellular processes. Results We identified the product of the Dictyostelium discoideum gpbB gene as the Dictyostelium RACK1 homolog. The protein is mainly cytosolic but can also associate with cellular membranes. DdRACK1 binds to phosphoinositides (PIPs) in protein-lipid overlay and liposome-binding assays. The basis of this activity resides in a basic region located in the extended loop between blades 6 and 7 as revealed by mutational analysis. Similar to RACK1 proteins from other organisms DdRACK1 interacts with G protein subunits alpha, beta and gamma as shown by yeast two-hybrid, pulldown, and immunoprecipitation assays. Unlike the Saccharomyces cerevisiae and Cryptococcus neoformans RACK1 proteins it does not appear to take over Gβ function in D. discoideum as developmental and other defects were not rescued in Gβ null mutants overexpressing GFP-DdRACK1. Overexpression of GFP-tagged DdRACK1 and a mutant version (DdRACK1mut) which carried a charge-reversal mutation in the basic region in wild type cells led to changes during growth and development. Conclusion DdRACK1 interacts with heterotrimeric G proteins and can through these interactions impact on processes specifically regulated by these proteins.
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Affiliation(s)
| | | | | | | | - Angelika A Noegel
- Institute of Biochemistry I, Medical Faculty, Center for Molecular Medicine Cologne (CMMC) and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50931 Köln, Germany.
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Benabentos R, Hirose S, Sucgang R, Curk T, Katoh M, Ostrowski EA, Strassmann JE, Queller DC, Zupan B, Shaulsky G, Kuspa A. Polymorphic members of the lag gene family mediate kin discrimination in Dictyostelium. Curr Biol 2009; 19:567-72. [PMID: 19285397 DOI: 10.1016/j.cub.2009.02.037] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Revised: 01/02/2009] [Accepted: 02/04/2009] [Indexed: 01/01/2023]
Abstract
Self and kin discrimination are observed in most kingdoms of life and are mediated by highly polymorphic plasma membrane proteins. Sequence polymorphism, which is essential for effective recognition, is maintained by balancing selection. Dictyostelium discoideum are social amoebas that propagate as unicellular organisms but aggregate upon starvation and form fruiting bodies with viable spores and dead stalk cells. Aggregative development exposes Dictyostelium to the perils of chimerism, including cheating, which raises questions about how the victims survive in nature and how social cooperation persists. Dictyostelids can minimize the cost of chimerism by preferential cooperation with kin, but the mechanisms of kin discrimination are largely unknown. Dictyostelium lag genes encode transmembrane proteins with multiple immunoglobulin (Ig) repeats that participate in cell adhesion and signaling. Here, we describe their role in kin discrimination. We show that lagB1 and lagC1 are highly polymorphic in natural populations and that their sequence dissimilarity correlates well with wild-strain segregation. Deleting lagB1 and lagC1 results in strain segregation in chimeras with wild-type cells, whereas elimination of the nearly invariant homolog lagD1 has no such consequences. These findings reveal an early evolutionary origin of kin discrimination and provide insight into the mechanism of social recognition and immunity.
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Affiliation(s)
- Rocio Benabentos
- Graduate Program in Cell and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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Matsuoka S, Kuwayama H, Ikeno D, Oyama M, Maeda M. Defect in peroxisomal multifunctional enzyme MFE1 affects cAMP relay in Dictyostelium. Dev Growth Differ 2005; 46:195-9. [PMID: 15066197 DOI: 10.1111/j.1440-169x.2004.00732.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have previously reported that cells of Dictyostelium discoideum lacking the fatty acid oxidation enzyme MFE1 accumulate excess cyclopropane fatty acids from ingested bacteria. Cells in which mfeA(-) is disrupted fail to develop when grown in association with bacteria but form normal fruiting bodies when grown in axenic media. Bacterially grown mfeA(-) cells express the genes for the cyclic AMP (cAMP) receptor (carA) and adenylyl cyclase (acaA) but fail to respond to a cAMP pulse by synthesis of additional cAMP which normally relays the signal. Moreover, they do not accumulate the adhesion protein, gp80, which is encoded by the cAMP-induced gene, csaA. As a consequence, they do not acquire developmentally regulated EDTA-resistant cell-cell adhesion. When mutant cells are mixed with wild-type cells and allowed to develop together, they co-aggregate and differentiate into both spores and stalk cells. Thus, most of the developmental consequences of excess cyclopropane fatty acids appear to result from impaired cAMP relay.
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Affiliation(s)
- Satomi Matsuoka
- Department of Biology, Graduate School of Science, Osaka University, 1-16 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
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6
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Mangiarotti G. Induction of ribosomal subunits misassembly by antisense RNAs to control cell growth. Exp Cell Res 2000; 259:266-73. [PMID: 10942598 DOI: 10.1006/excr.2000.4956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The assembly of ribosomal subunits starting from free ribosomal RNA and protein of Dictyostelium discoideum was induced in vitro in the presence of several oligoribonucleotides complementary to defined sequences of ribosomal RNA. The reconstituted particles had a full complement of ribosomal proteins, but did not function in an in vitro protein synthesis system and were disassembled following interaction with mRNA. The same result was obtained in vivo by fusing the oligodeossiribonucleotides coding for the selected oligoribonucleotides to the promoter of the gene coding for contact site A protein. This gene is expressed only in the first part of development. Transfected growing cells, transferred in developing buffer in the presence of pulses of cAMP, accumulated significant amounts of the oligoribonucleotides. When retransferred to the growth medium, they grew progressively more slowly, until their doubling time doubled, apparently due to the availability of a limiting amount of functional ribosomes. To avoid disassembly of misassembled subunits (G. Mangiarotti et al., 1997, J. Biol. Chem. 272, 27818-27822), two oligoribonucleotides complementary to sequences present at the 5' ends of pre-17S and pre-26S RNAs were also induced to accumulate during early development with the same technique. When transfected cells were retransferred to the growth medium, their rate of growth declined rapidly to zero and cells died, apparently because they were unable to disassemble misassembled ribosomal subunits and avoid their entry into polyribosomes. This technique to perturb protein synthesis, arrest cell growth, and cause cell suicide will be tested in abnormally growing animal cells.
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Affiliation(s)
- G Mangiarotti
- Dipartimento di Fisiopatologia Clinica, University of Torino, Via Genova 3, Torino, 10126, Italy
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Chien S, Chung CY, Sukumaran S, Osborne N, Lee S, Ellsworth C, McNally JG, Firtel RA. The Dictyostelium LIM domain-containing protein LIM2 is essential for proper chemotaxis and morphogenesis. Mol Biol Cell 2000; 11:1275-91. [PMID: 10749929 PMCID: PMC14846 DOI: 10.1091/mbc.11.4.1275] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
We have identified limB, a gene encoding a novel LIM domain-containing protein, LIM2, in a screen for genes required for morphogenesis. limB null cells aggregate, although poorly, but they are unable to undergo morphogenesis, and the aggregates arrest at the mound stage. limB null cells exhibit an aberrant actin cytoskeleton and have numerous F-actin-enriched microspikes. The cells exhibit poor adhesion to a substratum and do not form tight cell-cell agglomerates in suspension. Furthermore, limB null cells are unable to properly polarize in chemoattractant gradients and move very poorly. Expression of limB from a prestalk-specific but not a prespore-specific promoter complements the morphogenetic defects of the limB null strain, suggesting that the limB null cell developmental defect results from an inability to properly sort prestalk cells. LIM2 protein is enriched in the cortex of wild-type cells, although it does not colocalize with the actin cytoskeleton. Our analysis indicates that LIM2 is a new regulatory protein that functions to control rearrangements of the actin cytoskeleton and is required for cell motility and chemotaxis. Our findings may be generally applicable to understanding pathways that control cell movement and morphogenesis in all multicellular organisms. Structure function studies on the LIM domains are presented.
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Affiliation(s)
- S Chien
- Section of Cell and Developmental Biology, Division of Biology, Center for Molecular Genetics, University of California, San Diego, USA
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8
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Chubb JR, Wilkins A, Thomas GM, Insall RH. The Dictyostelium RasS protein is required for macropinocytosis, phagocytosis and the control of cell movement. J Cell Sci 2000; 113 ( Pt 4):709-19. [PMID: 10652263 DOI: 10.1242/jcs.113.4.709] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Endocytosis and cell migration both require transient localised remodelling of the cell cortex. Several lines of evidence suggest a key regulatory role in these activities for members of the Ras family of small GTPases. We have generated Dictyostelium cells lacking one member of this family, RasS, and the mutant cells are perturbed in endocytosis and cell migration. Mutant amoebae are defective in phagocytosis and fluid-phase endocytosis and are impaired in growth. Conversely, the rasS(-)cells show an enhanced rate of cell migration, moving three times faster than wild-type controls. The mutant cells display an aberrant morphology, are highly polarised, carry many elongated actin protrusions and show a concomitant decrease in formation of pinocytic crowns on the cell surface. These morphological aberrations are paralleled by changes in the actin cytoskeleton, with a significant proportion of the cortical F-actin relocalised to prominent pseudopodia. Rapid migration and endocytosis appear to be mutually incompatible and it is likely that RasS protein is required to maintain the normal balance between these two actin-dependent processes.
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Affiliation(s)
- J R Chubb
- MRC Laboratory for Molecular Cell Biology, Department of Physiology, University College London, Gower Street, London WC1E 6BT, UK
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Aubry L, Firtel R. Integration of signaling networks that regulate Dictyostelium differentiation. Annu Rev Cell Dev Biol 1999; 15:469-517. [PMID: 10611970 DOI: 10.1146/annurev.cellbio.15.1.469] [Citation(s) in RCA: 137] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In Dictyostelium amoebae, cell-type differentiation, spatial patterning, and morphogenesis are controlled by a combination of cell-autonomous mechanisms and intercellular signaling. A chemotactic aggregation of approximately 10(5) cells leads to the formation of a multicellular organism. Cell-type differentiation and cell sorting result in a small number of defined cell types organized along an anteroposterior axis. Finally, a mature fruiting body is created by the terminal differentiation of stalk and spore cells. Analysis of the regulatory program demonstrates a role for several molecules, including GSK-3, signal transducers and activators of transcription (STAT) factors, and cAMP-dependent protein kinase (PKA), that control spatial patterning in metazoans. Unexpectedly, two component systems containing histidine kinases and response regulators also play essential roles in controlling Dictyostelium development. This review focuses on the role of cAMP, which functions intracellularly to mediate the activity of PKA, an essential component in aggregation, cell-type specification, and terminal differentiation. Cytoplasmic cAMP levels are controlled through both the regulated activation of adenylyl cyclases and the degradation by a phosphodiesterase containing a two-component system response regulator. Extracellular cAMP regulates G-protein-dependent and -independent pathways to control aggregation as well as the activity of GSK-3 and the transcription factors GBF and STATa during multicellular development. The integration of these pathways with others regulated by the morphogen DIF-1 to control cell fate decisions are discussed.
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Affiliation(s)
- L Aubry
- CEA-Grenoble DBMS/BBSI, France
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10
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Stocker S, Hiery M, Marriott G. Phototactic migration of Dictyostelium cells is linked to a new type of gelsolin-related protein. Mol Biol Cell 1999; 10:161-78. [PMID: 9880334 PMCID: PMC25161 DOI: 10.1091/mbc.10.1.161] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The molecular and functional characterization of a 125-kDa Ca2+-extractable protein of the Triton X-100-insoluble fraction of Dictyostelium cells identified a new type of a gelsolin-related molecule. In addition to its five gelsolin segments, this gelsolin-related protein of 125 kDa (GRP125) reveals a number of unique domains, two of which are predicted to form coiled-coil regions. Another distinct attribute of GRP125 concerns the lack of sequence elements known to be essential for characteristic activities of gelsolin-like proteins, i.e. the severing, capping, or nucleation of actin filaments. The subcellular distribution of GRP125 to vesicular compartments suggests an activity of GRP125 different from actin-binding, gelsolin-related proteins. GRP125 expression is tightly regulated and peaks at the transition to the multicellular pseudoplasmodial stage of Dictyostelium development. GRP125 was found indispensable for slug phototaxis, because slugs fail to correctly readjust their orientation in the absence of GRP125. Analysis of the GRP125-deficient mutant showed that GRP125 is required for coupling photodetection to the locomotory machinery of slugs. We propose that GRP125 is essential in the natural environment for the propagation of Dictyostelium spores. We also present evidence for further representatives of the GRP125 type in Dictyostelium, as well as in heterologous cells from lower to higher eukaryotes.
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Affiliation(s)
- S Stocker
- Max-Planck-Institute for Biochemistry, D-82152 Martinsried, Germany
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11
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Verkerke-Van Wijk I, Kim JY, Brandt R, Devreotes PN, Schaap P. Functional promiscuity of gene regulation by serpentine receptors in Dictyostelium discoideum. Mol Cell Biol 1998; 18:5744-9. [PMID: 9742091 PMCID: PMC109160 DOI: 10.1128/mcb.18.10.5744] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/1998] [Accepted: 06/30/1998] [Indexed: 11/20/2022] Open
Abstract
Serpentine receptors such as smoothened and frizzled play important roles in cell fate determination during animal development. In Dictyostelium discoideum, four serpentine cyclic AMP (cAMP) receptors (cARs) regulate expression of multiple classes of developmental genes. To understand their function, it is essential to know whether each cAR is coupled to a specific gene regulatory pathway or whether specificity results from the different developmental regulation of individual cARs. To distinguish between these possibilities, we measured gene induction in car1 car3 double mutant cell lines that express equal levels of either cAR1, cAR2, or cAR3 under a constitutive promoter. We found that all cARs efficiently mediate both aggregative gene induction by cAMP pulses and induction of postaggregative and prespore genes by persistent cAMP stimulation. Two exceptions to this functional promiscuity were observed. (i) Only cAR1 can mediate adenosine inhibition of cAMP-induced prespore gene expression, a phenomenon that was found earlier in wild-type cells. cAR1's mediation of adenosine inhibition suggests that cAR1 normally mediates prespore gene induction. (ii) Only cAR2 allows entry into the prestalk pathway. Prestalk gene expression is induced by differentiation-inducing factor (DIF) but only after cells have been prestimulated with cAMP. We found that DIF-induced prestalk gene expression is 10 times higher in constitutive cAR2 expressors than in constitutive cAR1 or cAR3 expressors (which still have endogenous cAR2), suggesting that cAR2 mediates induction of DIF competence. Since in wild-type slugs cAR2 is expressed only in anterior cells, this could explain the so far puzzling observations that prestalk cells differentiate at the anterior region but that DIF levels are actually higher at the posterior region. After the initial induction of DIF competence, cAMP becomes a repressor of prestalk gene expression. This function can again be mediated by cAR1, cAR2, and cAR3.
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Affiliation(s)
- I Verkerke-Van Wijk
- Cell Biology Section, Institute for Molecular Plant Sciences, University of Leiden, 2333 AL Leiden, The Netherlands
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12
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Bracco E, Peracino B, Noegel AA, Bozzaro S. Cloning and transcriptional regulation of the gene encoding the vacuolar/H+ ATPase B subunit of Dictyostelium discoideum. FEBS Lett 1997; 419:37-40. [PMID: 9426215 DOI: 10.1016/s0014-5793(97)01425-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The main function of vacuolar H+ ATPases in eukaryotic cells is to generate proton and electrochemical gradients across the membrane of inner compartments. We have isolated the gene encoding the B subunit of Dictyostelium discoideum vacuolar H+ ATPase (vatB) and analyzed its transcriptional regulation. The deduced protein comprises 493 amino acids with a calculated molecular mass of 54874 Da. The predicted protein sequence is highly homologous to previously determined V/H+ ATPase B subunit sequences. The protein is encoded by a single gene in the Dictyostelium genome. The gene is maximally expressed during growth and it decreases during the first hours of development. Gene expression is rapidly enhanced by phagocytosis, but not by fluid-phase endocytosis. Acidic and alkaline conditions affect vatB gene expression differently.
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Affiliation(s)
- E Bracco
- Dipartimento di Scienze Cliniche e Biologiche, Università di Torino, Ospedale S. Luigi Gonzaga, Orbassano-Turin, Italy
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13
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Rivero F, Köppel B, Peracino B, Bozzaro S, Siegert F, Weijer CJ, Schleicher M, Albrecht R, Noegel AA. The role of the cortical cytoskeleton: F-actin crosslinking proteins protect against osmotic stress, ensure cell size, cell shape and motility, and contribute to phagocytosis and development. J Cell Sci 1996; 109 ( Pt 11):2679-91. [PMID: 8937986 DOI: 10.1242/jcs.109.11.2679] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We generated Dictyostelium double mutants lacking the two F-actin crosslinking proteins alpha-actinin and gelation factor by inactivating the corresponding genes via homologous recombination. Here we investigated the consequences of these deficiencies both at the single cell level and at the multicellular stage. We found that loss of both proteins severely affected growth of the mutant cells in shaking suspension, and led to a reduction of cell size from 12 microns in wild-type cells to 9 microns in mutant cells. Moreover the cells did not exhibit the typical polarized morphology of aggregating Dictyostelium cells but had a more rounded cell shape, and also exhibited an increased sensitivity towards osmotic shock and a reduced rate of phagocytosis. Development was heavily impaired and never resulted in the formation of fruiting bodies. Expression of developmentally regulated genes and the final developmental stages that were reached varied, however, with the substrata on which the cells were deposited. On phosphate buffered agar plates the cells were able to form tight aggregates and mounds and to express prespore and prestalk cell specific genes. Under these conditions the cells could perform chemotactic signalling and cell behavior was normal at the onset of multicellular development as revealed by time-lapse video microscopy. Double mutant cells were motile but speed was reduced by approximately 30% as compared to wild type. These changes were reversed by expressing the gelation factor in the mutant cells. We conclude that the actin assemblies that are formed and/or stabilized by both F-actin crosslinking proteins have a protective function during osmotic stress and are essential for proper cell shape and motility.
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Affiliation(s)
- F Rivero
- Max-Planck-Institut für Biochemie, Martinsried, Germany
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14
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Schuster SC, Noegel AA, Oehme F, Gerisch G, Simon MI. The hybrid histidine kinase DokA is part of the osmotic response system of Dictyostelium. EMBO J 1996; 15:3880-9. [PMID: 8670893 PMCID: PMC452086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
We have used PCR to identify a Dictyostelium homolog of the bacterial two-component system. The gene dokA codes for a member of the hybrid histidine kinase family which is defined by the presence of conserved amino acid sequence motifs corresponding to an N-terminal receptor domain, a central kinase and a C-terminal response regulator moiety. Potential function of the regulator domain was demonstrated by phosphorylation in vitro. dokA mutants are deficient in the osmoregulatory pathway, resulting in premature cell death under high osmotic stress. Under less stringent osmotic conditions, cells grow at a normal rate, but development at the multicellular stage is altered. dokA is a member of a family of histidine kinase-like genes that play regulatory roles in eukaryotic cell function.
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Affiliation(s)
- S C Schuster
- Abteilung fur Membranebiochemie, Max-Planck-Institut für Biochemie, 82152 Martinsried, Germany
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15
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Lipke PN. Cell adhesion proteins in the nonvertebrate eukaryotes. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 1996; 17:119-57. [PMID: 8822803 DOI: 10.1007/978-3-642-80106-8_7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- P N Lipke
- Department of Biological Sciences, Hunter College of the City University of New York, New York 10021, USA
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Wetterauer BW, Salger K, Carballo-Metzner C, MacWilliams HK. Cell-density-dependent repression of discoidin in Dictyostelium discoideum. Differentiation 1995; 59:289-97. [PMID: 8882814 DOI: 10.1046/j.1432-0436.1996.5950289.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
When Dictyostelium discoideum cells are grown on bacteria, their natural food source, the discoidin genes are induced by cell-density-sensing factors before the food supply is exhausted [11, 18], and expression increases continuously thereafter. This regulation pattern is changed when cells are grown in axenic medium: the discoidins are induced at a considerably lower cell density and are no longer expressed in stationary phase [13]. We have investigated this phenomenon further and show that repression begins when cells are still in exponential growth. It occurs at the level of transcription and involves an element of the discoidin I gamma promoter for which no function has previously been described. Since the effect of high cell density can be mimicked by conditioned medium, it appears that the repression is due to an extracellular signal. This signal is neither ammonia, nor folate, nor cAMP, the known repressors of discoidin expression.
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Affiliation(s)
- B W Wetterauer
- Zoologisches Institut der Ludwig-Maximilians-Universität, München, Germany
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17
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Yoshida M, Matsui T, Fuse G, Ouchi S. Carbohydrate structures of the cell adhesion molecule, contact site A, from Dictyostelium discoideum. FEBS Lett 1993; 318:305-9. [PMID: 8440387 DOI: 10.1016/0014-5793(93)80534-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We determined the carbohydrate structures of contact site A from Dictyostelium discoideum. The carbohydrate moieties of contact site A were released by hydrazinolysis. Fractionation of the deacidified oligosaccharide mixture by Bio-Gel P-4 column chromatography revealed that it was composed of four major oligosaccharides. Their respective structures were determined by sequential exoglycosidase digestion. It is known that contact site A consists of two kinds of carbohydrates, I and II. Taking together the previous and the present results, it was deduced that carbohydrate I comprises N-linked oligosaccharides and carbohydrate II O-linked ones. Furthermore, the relative molar contents of GalNAc and GlcNAc in reducing terminal suggested that contact site A contains 67% of N-linked and 33% of O-linked oligosaccharides.
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Affiliation(s)
- M Yoshida
- Research Institute of Food Science, Kinki University, Higashi-Osaka, Japan
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18
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McPherson CE, Singleton CK. V4, a gene required for the transition from growth to development in Dictyostelium discoideum. Dev Biol 1992; 150:231-42. [PMID: 1312963 DOI: 10.1016/0012-1606(92)90238-c] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The V4 gene of Dictyostelium discoideum is regulated in a nutrient-dependent manner and is deactivated immediately upon the onset of development. V4 is expressed only during growth, but its expression is not required for growth. We propose that the V4 gene product plays a role in the transition from growth to development. We have tested this hypothesis by antisense mutagenesis. Cells transformed with a V4 antisense construct contained no detectable endogenous V4 mRNA. These cells grew normally, but they failed to aggregate. Under conditions which normally promote development, V4 antisense transformants failed to deactivate vegetative-specific genes. These cells also were unable to induce the expression of the cAMP cell surface receptor, the cyclic nucleic phosphodiesterase, and contact sites A, all of which are normally induced under such conditions. Surprisingly, cells transformed with a V4 sense construct displayed a similar morphological and biochemical phenotype as the antisense cells, whereas cells transformed with the parental vector exhibited a normal biochemical and morphological phenotype. These results demonstrate that expression of the V4 gene during growth is required for the proper initiation of development.
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MESH Headings
- 3',5'-Cyclic-AMP Phosphodiesterases/genetics
- Amino Acid Sequence
- Animals
- Base Sequence
- Chloramphenicol O-Acetyltransferase/genetics
- Chloramphenicol O-Acetyltransferase/metabolism
- DNA, Fungal/genetics
- DNA, Fungal/isolation & purification
- Dictyostelium/genetics
- Dictyostelium/growth & development
- Genes, Fungal
- Molecular Sequence Data
- Plasmids
- Promoter Regions, Genetic
- RNA, Antisense
- RNA, Fungal/genetics
- RNA, Fungal/isolation & purification
- RNA, Messenger/genetics
- Receptors, Cyclic AMP/genetics
- Recombinant Proteins/metabolism
- Restriction Mapping
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Affiliation(s)
- C E McPherson
- Department of Molecular Biology, Vanderbilt University, Nashville, Tennessee 37235
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19
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Witke W, Schleicher M, Noegel AA. Redundancy in the microfilament system: abnormal development of Dictyostelium cells lacking two F-actin cross-linking proteins. Cell 1992; 68:53-62. [PMID: 1732064 DOI: 10.1016/0092-8674(92)90205-q] [Citation(s) in RCA: 126] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We generated by gene disruption Dictyostelium cells that lacked both the F-actin cross-linking proteins, alpha-actinin and gelation factor. Several major cell functions, such as growth, chemotaxis, phagocytosis, and pinocytosis, were apparently unaltered. However, in all double mutants, development was greatly impaired. After formation of aggregates, cells were very rarely able to form fruiting bodies. This ability was rescued when mutant and wild-type strains were mixed in a ratio of 70 to 30. The developmental program in the mutant was not arrested, since the expression pattern of early and late genes remained unchanged. Development of the mutant was rendered normal when a functional alpha-actinin gene was introduced and expressed, showing the morphogenetic defect to be due to the absence of the two F-actin cross-linking proteins. These findings suggest the existence of a functional network allowing mutual complementation of certain actin-binding proteins.
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Affiliation(s)
- W Witke
- Max Planck Institute for Biochemistry, Martinsried, Federal Republic of Germany
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20
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Döring V, Schleicher M, Noegel A. Dictyostelium annexin VII (synexin). cDNA sequence and isolation of a gene disruption mutant. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(19)47401-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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21
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Purification and cDNA-derived sequence of adenylosuccinate synthetase from Dictyostelium discoideum. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)52269-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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22
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Chandrasekhar A, Rotman M, Kraft B, Soll DR. Developmental mechanisms regulating the rapid decrease in a cohesion glycoprotein mRNA in Dictyostelium function primarily at the level of mRNA degradation. Dev Biol 1990; 141:262-9. [PMID: 2210035 DOI: 10.1016/0012-1606(90)90382-s] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
During the morphogenetic program in Dictyostelium discoideum, the transcript of the gene encoding the cohesion glycoprotein gp80 accumulates to a maximum level between 4 and 6 hr, (just prior to the onset of aggregation), remains high between 6 and 10 hr (the ripple to loose aggregate stages), and then decreases to less than 10% of the maximum level between 10 and 12 hr (the tight aggregate stage). The level of gp80 transcript also decreases precipitously at the time of the erasure event in the program of dedifferentiation, or when cAMP is added to a dedifferentiating cell population prior to the erasure event. In the dedifferentiation-defective mutant HI4, the cAMP-stimulated system for rapidly reducing the level of gp80 transcript is intact, but the mechanism functioning at the time of the erasure event is defective, demonstrating that the two reduction mechanisms are dissociable. By comparing the levels of gp80 transcript with the levels of in vitro transcription of the gene in isolated nuclei, it is demonstrated that the rapid reduction of gp80 transcript immediately after aggregation and immediately after addition of 10(-4) M cAMP are the result of increased transcript degradation. The rapid reduction of gp80 transcript at the erasure event may also be due to increased transcript degradation, but transcriptional regulation cannot be completely ruled out in this case.
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23
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Wiesmüller L, Noegel AA, Bârzu O, Gerisch G, Schleicher M. cDNA-derived sequence of UMP-CMP kinase from Dictyostelium discoideum and expression of the enzyme in Escherichia coli. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)39331-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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24
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Abstract
In recent years considerable progress has been made in the identification and characterization of molecules that mediate cell adhesion during animal development. This review attempts to pick out from the vast amount of information in this rapidly expanding field some of the key features of adhesion molecules, to present ideas about their role in development, and to indicate the directions in which the field is now moving.
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Affiliation(s)
- H Anderson
- Department of Zoology, University of California, Davis 95616
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25
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26
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Müller-Taubenberger A, Westphal M, Noegel A, Gerisch G. A developmentally regulated gene product from Dictyostelium discoideum shows high homology to human alpha-L-fucosidase. FEBS Lett 1989; 246:185-92. [PMID: 2540036 DOI: 10.1016/0014-5793(89)80280-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A cDNA library of poly(A+)-RNA has been prepared from membrane-bound polysomes of Dictyostelium discoideum and screened for clones hybridizing to mRNA species that encode developmentally regulated proteins. The clone investigated in this paper recognizes a 1.8 kb transcript that accumulates strongly between the growth phase and aggregation stage. Stimulation of cells with pulses of cAMP enhances the accumulation. The amino acid sequence derived from a complete cDNA and from a genomic clone displays extensive sequence identity to human liver alpha-L-fucosidase. The D. discoideum DNA sequence encodes a 50.5 kDa polypeptide with a hydrophobic signal peptide at the N-terminus. Antibodies against a synthetic peptide corresponding to amino acids 262-275 of the deduced protein sequence recognize a developmentally regulated 50 kDa protein in D. discoideum that is recovered in the particulate fraction.
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27
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28
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André E, Lottspeich F, Schleicher M, Noegel A. Severin, gelsolin, and villin share a homologous sequence in regions presumed to contain F-actin severing domains. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(19)35412-2] [Citation(s) in RCA: 109] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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29
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Bloodgood RA, Salomonsky NL, Reinhart FD. Use of carbohydrate probes in conjunction with fluorescence-activated cell sorting to select mutant cell lines of Chlamydomonas with defects in cell surface glycoproteins. Exp Cell Res 1987; 173:572-85. [PMID: 3691676 DOI: 10.1016/0014-4827(87)90296-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Two carbohydrate-binding probes (the lectin concanavalin A and the anti-carbohydrate monoclonal antibody FMG-1) have been utilized in conjunction with fluorescence-activated cell sorting to select cell lines of Chlamydomonas reinhardtii that contain defects in cell surface-exposed glycoproteins. Two very different selection strategies (sorting cells with the lowest binding for the FMG-1 monoclonal antibody or the highest binding of concanavalin A) yield a class of mutant cells that exhibit a total lack of binding of the monoclonal antibody to cell wall and plasma membrane glycoproteins along with an increased affinity for concanavalin A. Detailed characterization of one such mutant cell line, designated L-23, is provided. The subtle glycosylation defect exhibited by this cell line does not alter the ability of the affected glycoproteins to be targeted to the flagellar membrane and does not affect the expression of flagellar surface motility, a phenomenon that appears to involve the major concanavalin A-binding glycoprotein of the flagellar membrane. This approach has general applicability for dissecting the role of carbohydrate epitopes in the targeting and function of any cell surface glycoprotein for which suitable carbohydrate probes are available.
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Affiliation(s)
- R A Bloodgood
- Department of Anatomy and Cell Biology, University of Virginia School of Medicine, Charlottesville 22908
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30
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Bozzaro S, Hagmann J, Noegel A, Westphal M, Calautti E, Bogliolo E. Cell differentiation in the absence of intracellular and extracellular cyclic AMP pulses in Dictyostelium discoideum. Dev Biol 1987. [DOI: 10.1016/0012-1606(87)90412-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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31
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Bozzaro S, Merkl R, Gerisch G. Cell adhesion: its quantification, assay of the molecules involved, and selection of defective mutants in Dictyostelium and Polysphondylium. Methods Cell Biol 1987; 28:359-85. [PMID: 3600412 DOI: 10.1016/s0091-679x(08)61657-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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