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Wojnacki J, Lujan AL, Brouwers N, Aranda-Vallejo C, Bigliani G, Rodriguez MP, Foresti O, Malhotra V. Tetraspanin-8 sequesters syntaxin-2 to control biphasic release propensity of mucin granules. Nat Commun 2023; 14:3710. [PMID: 37349283 PMCID: PMC10287693 DOI: 10.1038/s41467-023-39277-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Accepted: 06/06/2023] [Indexed: 06/24/2023] Open
Abstract
Agonist-mediated stimulated pathway of mucin and insulin release are biphasic in which rapid fusion of pre-docked granules is followed by slow docking and fusion of granules from the reserve pool. Here, based on a cell-culture system, we show that plasma membrane-located tetraspanin-8 sequesters syntaxin-2 to control mucin release. Tetraspanin-8 affects fusion of granules during the second phase of stimulated mucin release. The tetraspanin-8/syntaxin-2 complex does not contain VAMP-8, which functions with syntaxin-2 to mediate granule fusion. We suggest that by sequestering syntaxin-2, tetraspanin-8 prevents docking of granules from the reserve pool. In the absence of tetraspanin-8, more syntaxin-2 is available for docking and fusion of granules and thus doubles the quantities of mucins secreted. This principle also applies to insulin release and we suggest a cell type specific Tetraspanin/Syntaxin combination is a general mechanism regulating the fusion of dense core granules.
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Affiliation(s)
- José Wojnacki
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Barcelona, Spain
| | - Agustin Leonardo Lujan
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Barcelona, Spain
| | - Nathalie Brouwers
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Barcelona, Spain
| | - Carla Aranda-Vallejo
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Gonzalo Bigliani
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Barcelona, Spain
| | - Maria Pena Rodriguez
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Barcelona, Spain
| | - Ombretta Foresti
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Barcelona, Spain
| | - Vivek Malhotra
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Barcelona, Spain.
- Universitat Pompeu Fabra (UPF), Barcelona, Spain.
- ICREA, Barcelona, Spain.
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2
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The ulcerative colitis-associated gene FUT8 regulates the quantity and quality of secreted mucins. Proc Natl Acad Sci U S A 2022; 119:e2205277119. [PMID: 36252012 PMCID: PMC9618082 DOI: 10.1073/pnas.2205277119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mucins are the main macrocomponents of the mucus layer that protects the digestive tract from pathogens. Fucosylation of mucins increases mucus viscoelasticity and its resistance to shear stress. These properties are altered in patients with ulcerative colitis (UC), which is marked by a chronic inflammation of the distal part of the colon. Here, we show that levels of Fucosyltransferase 8 (FUT8) and specific mucins are increased in the distal inflamed colon of UC patients. Recapitulating this FUT8 overexpression in mucin-producing HT29-18N2 colonic cell line increases delivery of MUC1 to the plasma membrane and extracellular release of MUC2 and MUC5AC. Mucins secreted by FUT8 overexpressing cells are more resistant to removal from the cell surface than mucins secreted by FUT8-depleted cells (FUT8 KD). FUT8 KD causes intracellular accumulation of MUC1 and alters the ratio of secreted MUC2 to MUC5AC. These data fit well with the Fut8-/- mice phenotype, which are protected from UC. Fut8-/- mice exhibit a thinner proximal colon mucus layer with an altered ratio of neutral to acidic mucins. Together, our data reveal that FUT8 modifies the biophysical properties of mucus by controlling levels of cell surface MUC1 and quantity and quality of secreted MUC2 and MUC5AC. We suggest that these changes in mucus viscoelasticity likely facilitate bacterial-epithelial interactions leading to inflammation and UC progression.
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Cantero-Recasens G, Butnaru CM, Brouwers N, Mitrovic S, Valverde MA, Malhotra V. Sodium channel TRPM4 and sodium/calcium exchangers (NCX) cooperate in the control of Ca 2+-induced mucin secretion from goblet cells. J Biol Chem 2018; 294:816-826. [PMID: 30482841 DOI: 10.1074/jbc.ra117.000848] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 11/21/2018] [Indexed: 01/08/2023] Open
Abstract
Regulated mucin secretion is essential for the formation of the mucus layer that protects the underlying epithelial cells from foreign particles. Alterations in the quantity or quality of secreted mucins are therefore detrimental to airway and colon physiology. Based on various biochemical assays in several human cell lines, we report here that Na+/Ca2+ exchanger 2 (NCX2) works in conjunction with transient receptor potential cation channel subfamily M member 4 (TRPM4), and perhaps TRPM5, Na+ channels to control Ca2+-mediated secretion of both mucin 2 (MUC2) and MUC5AC from HT29-18N2 colonic cancer cells. Differentiated normal bronchial epithelial (NHBE) cells and tracheal cells from patients with cystic fibrosis (CFT1-LC3) expressed only TRPM4 and all three isoforms of NCXs. Blocking the activity of TRPM4 or NCX proteins abrogated MUC5AC secretion from NHBE and CFT1-LC3 cells. Altogether, our findings reveal that NCX and TRPM4/TRPM5 are both required for mucin secretion. We therefore propose that these two proteins could be potential pharmacological targets to control mucus-related pathologies such as cystic fibrosis.
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Affiliation(s)
- Gerard Cantero-Recasens
- From the Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain
| | - Cristian M Butnaru
- From the Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain
| | - Nathalie Brouwers
- From the Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain
| | - Sandra Mitrovic
- the University Hospital of Basel, Clinical Chemistry, Petersgraben 4, 4031 Basel, Switzerland
| | - Miguel A Valverde
- the Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, 08003 Barcelona, Catalonia, Spain, and
| | - Vivek Malhotra
- From the Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain, .,the Universitat Pompeu Fabra (UPF), Barcelona, Spain.,the Institució Catalana de Recerca i Estudis Avançats (ICREA), Pg. Lluis Companys 23, 08010 Barcelona, Spain
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Mitrovic S, Nogueira C, Cantero-Recasens G, Kiefer K, Fernández-Fernández JM, Popoff JF, Casano L, Bard FA, Gomez R, Valverde MA, Malhotra V. TRPM5-mediated calcium uptake regulates mucin secretion from human colon goblet cells. eLife 2013; 2:e00658. [PMID: 23741618 PMCID: PMC3667631 DOI: 10.7554/elife.00658] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Accepted: 04/23/2013] [Indexed: 12/23/2022] Open
Abstract
Mucin 5AC (MUC5AC) is secreted by goblet cells of the respiratory tract and, surprisingly, also expressed de novo in mucus secreting cancer lines. siRNA-mediated knockdown of 7343 human gene products in a human colonic cancer goblet cell line (HT29-18N2) revealed new proteins, including a Ca(2+)-activated channel TRPM5, for MUC5AC secretion. TRPM5 was required for PMA and ATP-induced secretion of MUC5AC from the post-Golgi secretory granules. Stable knockdown of TRPM5 reduced a TRPM5-like current and ATP-mediated Ca(2+) signal. ATP-induced MUC5AC secretion depended strongly on Ca(2+) influx, which was markedly reduced in TRPM5 knockdown cells. The difference in ATP-induced Ca(2+) entry between control and TRPM5 knockdown cells was abrogated in the absence of extracellular Ca(2+) and by inhibition of the Na(+)/Ca(2+) exchanger (NCX). Accordingly, MUC5AC secretion was reduced by inhibition of NCX. Thus TRPM5 activation by ATP couples TRPM5-mediated Na(+) entry to promote Ca(2+) uptake via an NCX to trigger MUC5AC secretion. DOI:http://dx.doi.org/10.7554/eLife.00658.001.
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Affiliation(s)
- Sandra Mitrovic
- Department of Cell and Developmental Biology , Centre for Genomic Regulation , Barcelona , Spain
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Perez-Vilar J, Mabolo R, McVaugh CT, Bertozzi CR, Boucher RC. Mucin granule intraluminal organization in living mucous/goblet cells. Roles of protein post-translational modifications and secretion. J Biol Chem 2005; 281:4844-55. [PMID: 16377632 DOI: 10.1074/jbc.m510520200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Recent studies suggest that the mucin granule lumen consists of a matrix meshwork embedded in a fluid phase. Secretory products can both diffuse, although very slowly, through the meshwork pores and interact noncovalently with the matrix. Using a green fluorescent protein-mucin fusion protein (SHGFP-MUC5AC/CK) as a FRAP (fluorescence recovery after photobleaching) probe, we have assessed in living mucous cells the relative importance of different protein post-translational modifications on the intragranular organization. Long term inhibition of mucin-type O-glycosylation, sialylation, or sulfation altered SHGFP-MUC5AC/CK characteristic diffusion time (t(1/2)), whereas all but sulfation diminished its mobile fraction. Reduction of protein disulfide bonds with tris(hydroxypropyl)phosphine resulted in virtually complete immobilization of the SHGFP-MUC5AC/CK intragranular pool. However, when activity of the vacuolar H+-ATPase was also inhibited, disulfide reduction decreased SHGFP-MUC5AC/CK t((1/2)) while diminishing its intraluminal concentration. Similar FRAP profiles were observed in granules that remained in the cells after the addition of a mucin secretagogue. Taken together these results suggest that: (a) the relative content of O-glycans and intragranular anionic groups is crucial for protein diffusion through the intragranular meshwork; (b) protein-protein, rather than carbohydrate-mediated, interactions are responsible for binding of SHGFP-MUC5AC/CK to the immobile fraction, although the degree of matrix O-glycosylation and sialylation affects such interactions; (c) intragranular organization does not depend on covalent multimerization of mucins or the presence of native disulfide bonds in the intragranular mucin/proteins, but rather on specific protein-mediated interactions that are important during the early stages of mucin matrix condensation; (d) alterations of the intragranular matrix precede granule discharge, which can be partial and, accordingly, does not necessarily involve the disappearance of the granule.
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Affiliation(s)
- Juan Perez-Vilar
- Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina, Chapel Hill, North Carolina 27599-7248, USA.
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Perez-Vilar J, Ribeiro CMP, Salmon WC, Mabolo R, Boucher RC. Mucin granules are in close contact with tubular elements of the endoplasmic reticulum. J Histochem Cytochem 2005; 53:1305-9. [PMID: 15923355 DOI: 10.1369/jhc.5b6713.2005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Live cell imaging methods were used to characterize goblet cells expressing a MUC5AC domain fused to enhanced green fluorescent protein that labels the granule lumen. Golgi complex and endosome/lysosome elements largely resided in the periphery of the granular mass. On the contrary, a tubular meshwork of endoplasmic reticulum (ER) was in close contact with the mucin granules. This meshwork could be identified in fixed native human bronchial goblet cells labeled with an anti-calreticulin antibody. The potential biological significance of this ER network for mucin secretion is discussed.
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Affiliation(s)
- Juan Perez-Vilar
- Cystic Fibrosis/Pulmonary Research and Treatment Center, School of Medicine, University of North Carolina at Chapel Hill, 27599-7248, USA.
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Perez-Vilar J, Olsen JC, Chua M, Boucher RC. pH-dependent intraluminal organization of mucin granules in live human mucous/goblet cells. J Biol Chem 2005; 280:16868-81. [PMID: 15718243 DOI: 10.1074/jbc.m413289200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To study the mechanism of gel-forming mucin packaging within mucin granules, we generated human mucous/goblet cells stably expressing a recombinant MUC5AC domain fused to green fluorescent protein (GFP). The fusion protein, named SHGFP-MUC5AC/CK, accumulated in the granules together with native MUC5AC. Inhibition of protein synthesis or disorganization of the Golgi complex did not result in diminished intragranular SHGFP-MUC5AC/CK signals, consistent with long-term storage of the fusion protein. However, SHGFP-MUC5AC/CK was rapidly discharged from the granules upon incubation of the cells with ATP, an established mucin secretagogue. Several criteria indicated that SHGFP-MUC5AC/CK was not covalently linked to endogenous MUC5AC. Analysis of fluorescence recovery after photobleaching suggested that the intragranular SHGFP-MUC5AC/CK mobile fraction and mobility were significantly lower than in the endoplasmic reticulum lumen. Incubation of the cells with bafilomycin A1, a specific inhibitor of the vacuolar H+-ATPase, did not alter the fusion protein mobility, although it significantly increased (approximately 20%) the intragranular SHGFP-MUC5AC/CK mobile fraction. In addition, the granules in bafilomycin-incubated cells typically exhibited a heterogeneous intraluminal distribution of the fluorescent fusion protein. These results are consistent with a model of mucin granule intraluminal organization with two phases: a mobile phase in which secretory proteins diffuse as in the endoplasmic reticulum lumen but at a lower rate and an immobile phase or matrix in which proteins are immobilized by noncovalent pH-dependent interactions. An intraluminal acidic pH, maintained by the vacuolar H+-ATPase, is one of the critical factors for secretory protein binding to the immobile phase and also for its organization.
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Affiliation(s)
- Juan Perez-Vilar
- Cystic Fibrosis/Pulmonary Research and Treatment Center, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599-7248, USA.
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Rodríguez BL, Rojas A, Campos J, Ledon T, Valle E, Toledo W, Fando R. Differential interleukin-8 response of intestinal epithelial cell line to reactogenic and nonreactogenic candidate vaccine strains of Vibrio cholerae. Infect Immun 2001; 69:613-6. [PMID: 11119564 PMCID: PMC97930 DOI: 10.1128/iai.69.1.613-616.2001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In this study, we analyzed whether attachment of Vibrio cholerae vaccine strains to human intestinal epithelial cells can induce an interleukin-8 (IL-8) response. The IL-8 transcripts were detected by PCR amplification of reverse-transcribed mRNA, and the gene product secretion was measured by an enzyme-linked immunosorbent assay. Infection of monolayers of the undifferentiated HT29-18N2 cell line with reactogenic (JBK70 and 81) and nonreactogenic (CVD103HgR and 638) vaccine strains of V. cholerae resulted in markedly higher IL-8 expression by epithelial cells exposed to reactogenic strains than by cells exposed to the nonreactogenic strains. Additionally, epithelial cells produced IL-8 transcripts following stimulation with cholera vaccine strains in a concentration-dependent manner. These results represent a new insight into the inflammatory component of reactogenicity and could be used as a predictive marker of vaccine reactogenicity prior to human testing.
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Affiliation(s)
- B L Rodríguez
- Departamento de Genética, Centro Nacional de Investigaciones Científicas, La Habana, Cuba.
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9
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Abstract
Cyclosporine is a potent immunosuppressant used in the treatment of ulcerative colitis and keratoconjunctivitis sicca. Neither the etiologies of these diseases nor the mechanism by which cyclosporine exerts its therapeutic effect is well understood. Since both diseases are linked by a common decrease in mucin-filled goblet cells, this study tests a hypothesis that cyclosporine acts directly on goblet cells to promote their differentiation and production of secretory mucins. The HT29-18N2 human colon adenocarcinoma cell line, which is capable of forming monolayers of well-differentiated goblet cells, was used as a model system. Cyclosporine induced a dose-dependent increase in intracellular mucin stores. A 2-week exposure to 1 microM cyclosporine resulted in an average increase in mucin volume of 94%. This increase resulted from both a higher percentage of cells with mucin stores and an increased volume of mucin per cell. PSC-833, a nonimmunosuppressive analog of cyclosporine, also increased mucin production. The intracellular accumulation of mucin was not a result of reduced secretion, since the time required for the release of pulse-radiolabeled glycoproteins was similar for both control and cyclosporine-treated monolayers. The effect of cyclosporine was not mediated by the drug's previously documented abilities to decrease cellular proliferation rates, inhibit calmodulin, antagonize prolactin receptor binding, or modulate prostaglandin production.
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Affiliation(s)
- T E Phillips
- Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211-7400, USA.
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Stanley CM, Phillips TE. Selective secretion and replenishment of discrete mucin glycoforms from intestinal goblet cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:G191-200. [PMID: 10409167 DOI: 10.1152/ajpgi.1999.277.1.g191] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Antibodies against MUC2, MUC3, and MUC5AC peptide epitopes stained the secretory contents of all goblet cells in the human colon-derived HT29-18N2 cell line. In contrast, four carbohydrate-specific monoclonal antibodies stained mucin glycoforms in consistent subsets of goblet cells. Cholinergic agonist-evoked decreases in total mucin stores were not always mirrored by proportional changes in mucin glycoforms in the same monolayers. Selective secretion of mucin glycoforms did not result from differences in receptor distribution, since cholinergic stimulation was found to increase intracellular free calcium in all cells and selective secretion was also observed when the cells were directly stimulated with the protein kinase C activator phorbol myristate acetate. The results demonstrate that goblet cells cycle through transient periods in which their exocytotic response is unresponsive to cholinergic or protein kinase C-mediated stimuli. Goblet cells replenished intracellular mucin stores to control levels within 1 h, but the relative proportion of mucin glycoforms was not always restored until 24 h after stimulation.
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Affiliation(s)
- C M Stanley
- Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211-7400, USA
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Bruno JG, Holwitt E, Kiel JL. Electrophoretic pattern changes in macrophage cell lines due to culture in protein-free medium. In Vitro Cell Dev Biol Anim 1998; 34:447-9. [PMID: 9661046 DOI: 10.1007/s11626-998-0076-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Bénitez JA, Spelbrink RG, Silva A, Phillips TE, Stanley CM, Boesman-Finkelstein M, Finkelstein RA. Adherence of Vibrio cholerae to cultured differentiated human intestinal cells: an in vitro colonization model. Infect Immun 1997; 65:3474-7. [PMID: 9234816 PMCID: PMC175493 DOI: 10.1128/iai.65.8.3474-3477.1997] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Choleragenic vibrios adhered to and multiplied on monolayers of the highly differentiated mucin-secreting cell line HT29-18N2. Their adherence followed first-order kinetics, was dependent on the concentration of vibrios, and was partially inhibited by lipopolysaccharide. Comparison of genetically modified vibrios showed that flagella, an active toxR gene, and the virulence cassette were not essential for initial binding. Inactivation of the hemagglutinin/protease increased binding. This highly differentiated human intestinal cell line provides a versatile new approach for studying major events occurring during intestinal colonization: adherence, multiplication, and detachment.
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Affiliation(s)
- J A Bénitez
- Centro Nacional de Investigaciones Científicas, Havana, Cuba
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