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Volumn 34, Issue 5, 1998, Pages 798-811

Distribution of intracellular nitrogen in marine microalgae: Basis for the calculation of specific nitrogen-to-protein conversion factors

Author keywords

Amino acids; Batch cultures; Chlorophyll; Intracellular inorganic nitrogen; Marine microalgae; Nitrogen to protein conversion factors; Nucleic acids; Total nitrogen; Total protein

Indexed keywords

MICROALGA; NITROGEN; NUTRIENT USE;

EID: 0031729595     PISSN: 00223646     EISSN: None     Source Type: Journal    
DOI: 10.1046/j.1529-8817.1998.340798.x     Document Type: Article
Times cited : (139)

References (55)
  • 1
    • 2942645572 scopus 로고
    • Effect of nitrate-N incorporation on the composition of the intracellular amino-acid pool of N-deprived Tetraselmis marina
    • Al-Amoudi, A. & Flynn, K. J. 1989. Effect of nitrate-N incorporation on the composition of the intracellular amino-acid pool of N-deprived Tetraselmis marina. Br. Phycol. 24:53-61.
    • (1989) Br. Phycol. , vol.24 , pp. 53-61
    • Al-Amoudi, A.1    Flynn, K.J.2
  • 3
    • 0003995078 scopus 로고
    • Washington, D.C.
    • Association of Official Analytical Chemists - AOAC. 1990. Official Methods of Analysis, 15th ed. Washington, D.C., 556 pp.
    • (1990) Official Methods of Analysis, 15th Ed.
  • 4
    • 85063425631 scopus 로고
    • Nutritional properties of microalgae: Potential and constraints
    • Richmond A. [Ed.] CRC Press, Boca Raton, Florida
    • Becker, E. W. 1986. Nutritional properties of microalgae: potential and constraints. In Richmond A. [Ed.] Handbook of Microalgal Mass Culture. CRC Press, Boca Raton, Florida, pp. 339-419.
    • (1986) Handbook of Microalgal Mass Culture , pp. 339-419
    • Becker, E.W.1
  • 5
    • 0008023995 scopus 로고
    • Variations in biochemical parameters of Heterocapsa sp. and Olisthodiscus luteus grown in 12:12 light:dark cycles. I. Cell cycle and nucleic acid composition
    • Berdalet, E., Latasa, M. & Estrada, M. 1992. Variations in biochemical parameters of Heterocapsa sp. and Olisthodiscus luteus grown in 12:12 light:dark cycles. I. Cell cycle and nucleic acid composition. Hydrobiologia 238:139-17.
    • (1992) Hydrobiologia , vol.238 , pp. 139-217
    • Berdalet, E.1    Latasa, M.2    Estrada, M.3
  • 6
    • 0028093989 scopus 로고
    • Effects of nitrogen and phosphorus starvation on nucleic acids and protein content of Heterocapsa sp
    • _ 1994. Effects of nitrogen and phosphorus starvation on nucleic acids and protein content of Heterocapsa sp. J. Plankton Res. 16:303-16.
    • (1994) J. Plankton Res. , vol.16 , pp. 303-316
  • 7
    • 34250081684 scopus 로고
    • A comparison of Lowry, Bradford and Smith protein assay using different protein standards and protein isolated from the marine diatom Thalassiosira pseudonana
    • Berges, J. A., Fisher, A. E. & Harrison, P. J. 1993. A comparison of Lowry, Bradford and Smith protein assay using different protein standards and protein isolated from the marine diatom Thalassiosira pseudonana. Mar. Biol. 115:187-93.
    • (1993) Mar. Biol. , vol.115 , pp. 187-193
    • Berges, J.A.1    Fisher, A.E.2    Harrison, P.J.3
  • 8
    • 0017184389 scopus 로고
    • A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein dye-binding
    • Bradford, M. 1976. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein dye-binding. Anal. Biohem. 72:248-54.
    • (1976) Anal. Biohem. , vol.72 , pp. 248-254
    • Bradford, M.1
  • 9
    • 0026046693 scopus 로고
    • The amino-acid and sugar composition of 16 species of microalgae used in mariculture
    • Brown, M. R. 1991. The amino-acid and sugar composition of 16 species of microalgae used in mariculture. J. Exp. Mar. Biol. Ecol. 145:79-99.
    • (1991) J. Exp. Mar. Biol. Ecol. , vol.145 , pp. 79-99
    • Brown, M.R.1
  • 10
    • 0000532229 scopus 로고
    • The gross and the amino acid compositions of batch and semi-continuous cultures of Isochrysis sp. (clone T.ISO), Pavlova lutheri and Nannochloropsis oculata
    • Brown, M. R., Garland, C. D., Jeffrey, S. W., Jameson, I. D. & Leroi, J. M. 1993. The gross and the amino acid compositions of batch and semi-continuous cultures of Isochrysis sp. (clone T.ISO), Pavlova lutheri and Nannochloropsis oculata. J. Appl. Phycol. 5:285-96.
    • (1993) J. Appl. Phycol. , vol.5 , pp. 285-296
    • Brown, M.R.1    Garland, C.D.2    Jeffrey, S.W.3    Jameson, I.D.4    Leroi, J.M.5
  • 11
    • 0000888751 scopus 로고
    • Evaluation of methods for the separation and analysis of proteins and free amino acids in phytoplankton samples
    • Clayton, J. R., Jr., Dortch, Q., Thorensen, S. & Ahmed, S. I. 1988. Evaluation of methods for the separation and analysis of proteins and free amino acids in phytoplankton samples. J. Plankton Res. 10:341-58.
    • (1988) J. Plankton Res. , vol.10 , pp. 341-358
    • Clayton Jr., J.R.1    Dortch, Q.2    Thorensen, S.3    Ahmed, S.I.4
  • 12
    • 84988201573 scopus 로고
    • Amino acid and total protein content of the edible mushroom Cantharellus cibarius (Fries)
    • Danell, E. & Eaker, D. 1992. Amino acid and total protein content of the edible mushroom Cantharellus cibarius (Fries). J. Sci. Food Agric. 60:333-7.
    • (1992) J. Sci. Food Agric. , vol.60 , pp. 333-337
    • Danell, E.1    Eaker, D.2
  • 13
    • 0002929101 scopus 로고
    • National Biomedical Research Foundation, Washington, D.C.
    • Dayhoff, M. O. 1972. Atlas of Protein Sequences and Structure, Vol. 5. National Biomedical Research Foundation, Washington, D.C., 179 pp.
    • (1972) Atlas of Protein Sequences and Structure , vol.5
    • Dayhoff, M.O.1
  • 14
    • 49049135253 scopus 로고
    • Effects of growth conditions on accumulation of internal pools of nitrate, ammonium, amino acids and protein in three marine diatoms
    • Dortch, Q. 1982. Effects of growth conditions on accumulation of internal pools of nitrate, ammonium, amino acids and protein in three marine diatoms. J. Exp. Mar. Biol. Ecol. 61:243-64.
    • (1982) J. Exp. Mar. Biol. Ecol. , vol.61 , pp. 243-264
    • Dortch, Q.1
  • 15
    • 0000052187 scopus 로고
    • Species differences in accumulation of nitrogen pools in phytoplankton
    • Dortch, Q., Clayton, J. R., Jr., Thorensen, S. S. & Ahmed, S. I. 1984. Species differences in accumulation of nitrogen pools in phytoplankton. Mar. Biol. 81:237-50.
    • (1984) Mar. Biol. , vol.81 , pp. 237-250
    • Dortch, Q.1    Clayton Jr., J.R.2    Thorensen, S.S.3    Ahmed, S.I.4
  • 16
    • 0022169402 scopus 로고
    • Nitrogen storage and use of biochemical indices to assess nitrogen deficiency and growth rate in natural plankton population
    • Dortch, Q., Clayton, J. R., Jr., Thorensen, S. S., Cleveland, J. S., Bressler, S. L. & Ahmed, S. I. 1985. Nitrogen storage and use of biochemical indices to assess nitrogen deficiency and growth rate in natural plankton population. J. Mar. Res. 43: 437-64.
    • (1985) J. Mar. Res. , vol.43 , pp. 437-464
    • Dortch, Q.1    Clayton Jr., J.R.2    Thorensen, S.S.3    Cleveland, J.S.4    Bressler, S.L.5    Ahmed, S.I.6
  • 17
    • 0002271256 scopus 로고
    • RNA/DNA ratios and DNA concentrations as indicators of growth rate and biomass in planktonic marine organisms
    • Dortch, Q., Roberts, T. L., Clayton, J. R., Jr. & Ahmed, S. I. 1983. RNA/DNA ratios and DNA concentrations as indicators of growth rate and biomass in planktonic marine organisms. Mar. Ecol. Prog. Ser. 13:61-71.
    • (1983) Mar. Ecol. Prog. Ser. , vol.13 , pp. 61-71
    • Dortch, Q.1    Roberts, T.L.2    Clayton Jr., J.R.3    Ahmed, S.I.4
  • 19
    • 38249040956 scopus 로고
    • Biomass production and biochemical composition in mass cultures of the marine microalga Isochrysis galbana Parke at varying nutrient concentrations
    • Fabregas, J., Herrero, C., Cabezas, B. & Abalde, J. 1986. Biomass production and biochemical composition in mass cultures of the marine microalga Isochrysis galbana Parke at varying nutrient concentrations. Aquaculture 53:101-13.
    • (1986) Aquaculture , vol.53 , pp. 101-113
    • Fabregas, J.1    Herrero, C.2    Cabezas, B.3    Abalde, J.4
  • 20
    • 0001789432 scopus 로고
    • Biomass production and variation in the biochemical profile (total protein, carbohydrates, RNA, lipids and fatty acids) of seven marine microalgae
    • Fernández-Reiriz, M. J., Perez-Camacho, A., Ferreiro, M. J., Blanco, J., Planas, M., Campos, M. J. & Labarta, U. 1989. Biomass production and variation in the biochemical profile (total protein, carbohydrates, RNA, lipids and fatty acids) of seven marine microalgae. Aquaculture 83:17-37.
    • (1989) Aquaculture , vol.83 , pp. 17-37
    • Fernández-Reiriz, M.J.1    Perez-Camacho, A.2    Ferreiro, M.J.3    Blanco, J.4    Planas, M.5    Campos, M.J.6    Labarta, U.7
  • 21
    • 0028038415 scopus 로고
    • Carbon-nitrogen relations at whole-cell and free-amino-acid levels during hatch growth of Isocrysis galbana (Primnesiophyceae) under conditions of altering light and dark
    • Flynn, K. J., Davidson, K. & Leftley, J. W. 1994. Carbon-nitrogen relations at whole-cell and free-amino-acid levels during hatch growth of Isocrysis galbana (Primnesiophyceae) under conditions of altering light and dark. Mar. Biol. 118:229-37.
    • (1994) Mar. Biol. , vol.118 , pp. 229-237
    • Flynn, K.J.1    Davidson, K.2    Leftley, J.W.3
  • 22
    • 51249161767 scopus 로고
    • Changes in fatty acids, amino acids and carbon/nitrogen biomass during nitrogen starvation of ammonium- and nitrate-grown Isochrysis galbana
    • Flynn, K. J., Garrido, J. L., Zapata, M., Öpik, H. & Hipkin, C. R. 1992. Changes in fatty acids, amino acids and carbon/nitrogen biomass during nitrogen starvation of ammonium- and nitrate-grown Isochrysis galbana. J. Appl. Phycol. 4:95-104.
    • (1992) J. Appl. Phycol. , vol.4 , pp. 95-104
    • Flynn, K.J.1    Garrido, J.L.2    Zapata, M.3    Öpik, H.4    Hipkin, C.R.5
  • 23
    • 84986431736 scopus 로고
    • Nitrogen-to-protein conversion factors for some common edible mushrooms
    • Fujihara, S., Katsuga, A., Aoyagi, Y. & Sugahara, T. 1995. Nitrogen-to-protein conversion factors for some common edible mushrooms. J. Food Sci. 60:1.045-7.
    • (1995) J. Food Sci. , vol.60 , pp. 1045-1047
    • Fujihara, S.1    Katsuga, A.2    Aoyagi, Y.3    Sugahara, T.4
  • 24
    • 0021572941 scopus 로고
    • Proximate biochemical composition and caloric content calculated from elemental CHN analysis: A stoichiometric concept
    • Gnaiger, E. & Bitterlich, G. 1984. Proximate biochemical composition and caloric content calculated from elemental CHN analysis: a stoichiometric concept. Oecologia 62:289-98.
    • (1984) Oecologia , vol.62 , pp. 289-298
    • Gnaiger, E.1    Bitterlich, G.2
  • 27
    • 0001927234 scopus 로고
    • Effects of nutrient and light limitation on the biochemical composition of phytoplankton
    • Harrison, P. J., Thompson, P. A. & Calderwood, G. S. 1990. Effects of nutrient and light limitation on the biochemical composition of phytoplankton. J. Appl. Phycol. 2:45-56.
    • (1990) J. Appl. Phycol. , vol.2 , pp. 45-56
    • Harrison, P.J.1    Thompson, P.A.2    Calderwood, G.S.3
  • 28
    • 0024249409 scopus 로고
    • Variation of the amino acid scores and of the nitrogen-to-protein conversion factors in barley grain as a function of nitrogen content as compared with wheat and rye
    • Huet, J. C., Baudet, J., Kaab, L. B. B. & Mossé, J. 1988. Variation of the amino acid scores and of the nitrogen-to-protein conversion factors in barley grain as a function of nitrogen content as compared with wheat and rye. Plant Foods Hum. Nutr. 38:175-88.
    • (1988) Plant Foods Hum. Nutr. , vol.38 , pp. 175-188
    • Huet, J.C.1    Baudet, J.2    Kaab, L.B.B.3    Mossé, J.4
  • 29
    • 0001396452 scopus 로고
    • New spectrophotometric equations for determining chlorophylls a, b, c1 and c2 in higher plants, algae and natural phytoplankton
    • Jeffrey, S. W. & Humphrey, G. F. 1975. New spectrophotometric equations for determining chlorophylls a, b, c1 and c2 in higher plants, algae and natural phytoplankton. Biochem. Physiol. Pflanz. 167:191-4.
    • (1975) Biochem. Physiol. Pflanz. , vol.167 , pp. 191-194
    • Jeffrey, S.W.1    Humphrey, G.F.2
  • 30
    • 0002548108 scopus 로고
    • Factors for converting percentages of nitrogen in foods and feeds into percentages of protein
    • Jones, D. B. 1931. Factors for converting percentages of nitrogen in foods and feeds into percentages of protein. USDA Circ. 183:1-21.
    • (1931) USDA Circ. , vol.183 , pp. 1-21
    • Jones, D.B.1
  • 32
    • 0026000120 scopus 로고
    • Photosynthetic quotients, new production and net community production in the open ocean
    • Laws, E. A. 1991. Photosynthetic quotients, new production and net community production in the open ocean. Deep-Sea Res. 38:143-67.
    • (1991) Deep-Sea Res. , vol.38 , pp. 143-167
    • Laws, E.A.1
  • 33
    • 0031568311 scopus 로고    scopus 로고
    • Changes in biochemical profile of Tetraselmis gracilis. I. Comparison of two culture media
    • Lourenço, S. O., Lanfer Marquez, U. M., Mancini-Filho, J., Barbarino, E. & Aidar, E. 1997. Changes in biochemical profile of Tetraselmis gracilis. I. Comparison of two culture media. Aquaculture 148:153-68.
    • (1997) Aquaculture , vol.148 , pp. 153-168
    • Lourenço, S.O.1    Lanfer Marquez, U.M.2    Mancini-Filho, J.3    Barbarino, E.4    Aidar, E.5
  • 36
    • 0000051087 scopus 로고
    • Nitrogen-to-protein conversion factors for tropical plant samples
    • Milton, K. & Dintzis, F. R. 1981. Nitrogen-to-protein conversion factors for tropical plant samples. Biotropica 13:177-84.
    • (1981) Biotropica , vol.13 , pp. 177-184
    • Milton, K.1    Dintzis, F.R.2
  • 37
    • 0000745311 scopus 로고
    • An evaluation of fluorescence techniques for measuring DNA and RNA in marine microorganisms
    • Mordy, C. W. & Carlson, D. J. 1991. An evaluation of fluorescence techniques for measuring DNA and RNA in marine microorganisms. Mar. Ecol. Prog. Ser. 73:283-93.
    • (1991) Mar. Ecol. Prog. Ser. , vol.73 , pp. 283-293
    • Mordy, C.W.1    Carlson, D.J.2
  • 38
    • 33751553722 scopus 로고
    • Nitrogen to protein conversion factor for ten cereals and six legumes or oilseeds. A reappraisal of its definition and determination. Variation according to species and to seed proteic content
    • Mossé, J. 1990. Nitrogen to protein conversion factor for ten cereals and six legumes or oilseeds. A reappraisal of its definition and determination. Variation according to species and to seed proteic content. J. Agric. Food Chem. 38:18-24.
    • (1990) J. Agric. Food Chem. , vol.38 , pp. 18-24
    • Mossé, J.1
  • 39
    • 0009773491 scopus 로고
    • The amino acid composition of whole sorghum grain in relation to its nitrogen content
    • Mossé, J., Baudet, J. & Huet, J. C. 1988. The amino acid composition of whole sorghum grain in relation to its nitrogen content. Cereal Chem. 65:271-7.
    • (1988) Cereal Chem. , vol.65 , pp. 271-277
    • Mossé, J.1    Baudet, J.2    Huet, J.C.3
  • 40
    • 84986845425 scopus 로고
    • Relationship between amino acid composition and nitrogen of foxtail (Italian) millet (Setaria italica) grain of different varieties
    • _ 1989. Relationship between amino acid composition and nitrogen of foxtail (Italian) millet (Setaria italica) grain of different varieties. J. Sci. Food Agric. 46:383-92.
    • (1989) J. Sci. Food Agric. , vol.46 , pp. 383-392
  • 41
    • 84985266671 scopus 로고
    • Amino acid profiles of common cultivated mushrooms including the identification of N-(N-γ-L-glutamyl-3-sulfo-L-alanyl)glycine in Flammulina velutipes
    • Ogawa, T., Oka, Y. & Sasaoka, K. 1987. Amino acid profiles of common cultivated mushrooms including the identification of N-(N-γ-L-glutamyl-3-sulfo-L-alanyl)glycine in Flammulina velutipes. J. Food Sci. 52:135-8.
    • (1987) J. Food Sci. , vol.52 , pp. 135-138
    • Ogawa, T.1    Oka, Y.2    Sasaoka, K.3
  • 42
    • 0020669405 scopus 로고
    • Determination of total protein
    • Peterson, G. L. 1983. Determination of total protein. Methods Enzymol. 91:95-119.
    • (1983) Methods Enzymol. , vol.91 , pp. 95-119
    • Peterson, G.L.1
  • 43
    • 51249178131 scopus 로고
    • Effect of light intensity in the biochemical and fatty acid composition of Isochrysis sp. and Nannochloropsis oculata for use in tropical aquaculture
    • Renaud, S. M., Parry, D. L., Thinh, L. V., Kuo, C., Padovan, A. & Sammy, N. 1991. Effect of light intensity in the biochemical and fatty acid composition of Isochrysis sp. and Nannochloropsis oculata for use in tropical aquaculture. J. Appl. Phycol. 3:43-53.
    • (1991) J. Appl. Phycol. , vol.3 , pp. 43-53
    • Renaud, S.M.1    Parry, D.L.2    Thinh, L.V.3    Kuo, C.4    Padovan, A.5    Sammy, N.6
  • 44
    • 0030250707 scopus 로고    scopus 로고
    • Determination of protein in foods: Comparison of net protein and crude protein (N X 6.25) values
    • Salo-Väänänen, P. P. & Koivistoinen, P. E. 1996. Determination of protein in foods: comparison of net protein and crude protein (N X 6.25) values. Food Chem. 57:27-31.
    • (1996) Food Chem. , vol.57 , pp. 27-31
    • Salo-Väänänen, P.P.1    Koivistoinen, P.E.2
  • 45
    • 32844460538 scopus 로고
    • Amino acid composition and nitrogen-to-protein conversion factors for animal and plant foods
    • Sosulski, F. W. & Imafidon, G. I. 1990. Amino acid composition and nitrogen-to-protein conversion factors for animal and plant foods. J. Agric. Food. Chem. 38:1.351-6.
    • (1990) J. Agric. Food. Chem. , vol.38 , pp. 1351-1356
    • Sosulski, F.W.1    Imafidon, G.I.2
  • 46
    • 0025211779 scopus 로고
    • Quantification of protein
    • Stoscheck, C. M. 1990. Quantification of protein. Methods Enzymol. 182:50-68.
    • (1990) Methods Enzymol. , vol.182 , pp. 50-68
    • Stoscheck, C.M.1
  • 47
    • 0001709206 scopus 로고
    • Comparison of methods for extracting intracellular pools of inorganic nitrogen from marine phytoplankton
    • Thorensen, S. S., Dortch, Q. & Ahmed, S. I. 1982. Comparison of methods for extracting intracellular pools of inorganic nitrogen from marine phytoplankton. J. Plankton Res. 4:695-704.
    • (1982) J. Plankton Res. , vol.4 , pp. 695-704
    • Thorensen, S.S.1    Dortch, Q.2    Ahmed, S.I.3
  • 49
    • 0001100329 scopus 로고
    • Cell characteristics and biochemical composition of Dunaliella primolecta Butcher conditioned at different concentrations of dissolved nitrogen
    • Uriarte, I., Farías, A., Hawkins, A. J. S. & Bayne, B. L. 1993. Cell characteristics and biochemical composition of Dunaliella primolecta Butcher conditioned at different concentrations of dissolved nitrogen. J. Appl. Phycol. 5:447-53.
    • (1993) J. Appl. Phycol. , vol.5 , pp. 447-453
    • Uriarte, I.1    Farías, A.2    Hawkins, A.J.S.3    Bayne, B.L.4
  • 50
    • 0001975364 scopus 로고
    • Experiments in the large scale culture of the larvae of Ostrea edulis
    • Ser. 2
    • Walne, P. R. 1966. Experiments in the large scale culture of the larvae of Ostrea edulis. Fish. Invest. (Lond.) (Ser. 2) 25:1-53.
    • (1966) Fish. Invest. (Lond.) , vol.25 , pp. 1-53
    • Walne, P.R.1
  • 51
    • 0023338642 scopus 로고
    • Total nitrogen determination of various sample types: A comparison of Hach, Kjeltec and Kjeldahl methods
    • Watkins, K. L., Veum, T. L. & Krause, G. F. 1987. Total nitrogen determination of various sample types: a comparison of Hach, Kjeltec and Kjeldahl methods. J. Assoc. Off. Anal. Chem. 70:410-2.
    • (1987) J. Assoc. Off. Anal. Chem. , vol.70 , pp. 410-412
    • Watkins, K.L.1    Veum, T.L.2    Krause, G.F.3
  • 52
    • 0001542790 scopus 로고
    • Biochemical composition and energy content of six species of phytoplankton used in mariculture of bivalves
    • Whyte, J. C. N. 1987. Biochemical composition and energy content of six species of phytoplankton used in mariculture of bivalves. Aquaculture 60:231-41.
    • (1987) Aquaculture , vol.60 , pp. 231-241
    • Whyte, J.C.N.1
  • 53
    • 0030063494 scopus 로고    scopus 로고
    • Protein contents, amino acid compositions and nitrogen-to-protein conversion factors for cassava roots
    • Yeoh, H. H. & Truong, V. D. 1996. Protein contents, amino acid compositions and nitrogen-to-protein conversion factors for cassava roots. J. Sci. Food Agric. 70:51-4.
    • (1996) J. Sci. Food Agric. , vol.70 , pp. 51-54
    • Yeoh, H.H.1    Truong, V.D.2
  • 54
    • 0028049137 scopus 로고
    • Leaf protein contents and nitrogen-to-protein conversion factors for 90 plant species
    • Yeoh, H. H. & Wee, Y. C. 1994. Leaf protein contents and nitrogen-to-protein conversion factors for 90 plant species. Food Chem. 49:245-50.
    • (1994) Food Chem. , vol.49 , pp. 245-250
    • Yeoh, H.H.1    Wee, Y.C.2
  • 55
    • 0004232308 scopus 로고    scopus 로고
    • Prentice Hall, Inc., Upper Saddle River, New Jersey
    • Zar, J. H. 1996. Biostatistical Analysis, 3rd ed. Prentice Hall, Inc., Upper Saddle River, New Jersey, 920 pp.
    • (1996) Biostatistical Analysis, 3rd Ed.
    • Zar, J.H.1


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