期刊论文详细信息
Biotechnology for Biofuels
Dynamic metabolomics differentiates between carbon and energy starvation in recombinant Saccharomyces cerevisiae fermenting xylose
Basti Bergdahl1  Dominik Heer2  Uwe Sauer2  Bärbel Hahn-Hägerdal1  Ed WJ van Niel1 
[1] Applied Microbiology, Lund University, PO Box 124, SE-221 00, Lund, Sweden
[2] ETH Zurich, Zurich, 8093, Switzerland
关键词: Bioethanol;    Starvation;    Metabolic status;    Xylose fermentation;    Yeast metabolism;    Metabolomics;   
Others  :  798294
DOI  :  10.1186/1754-6834-5-34
 received in 2011-11-15, accepted in 2012-04-23,  发布年份 2012
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【 摘 要 】

Background

The concerted effects of changes in gene expression due to changes in the environment are ultimately reflected in the metabolome. Dynamics of metabolite concentrations under a certain condition can therefore give a description of the cellular state with a high degree of functional information. We used this potential to evaluate the metabolic status of two recombinant strains of Saccharomyces cerevisiae during anaerobic batch fermentation of a glucose/xylose mixture. Two isogenic strains were studied, differing only in the pathways used for xylose assimilation: the oxidoreductive pathway with xylose reductase (XR) and xylitol dehydrogenase (XDH) or the isomerization pathway with xylose isomerase (XI). The isogenic relationship between the two strains ascertains that the observed responses are a result of the particular xylose pathway and not due to unknown changes in regulatory systems. An increased understanding of the physiological state of these strains is important for further development of efficient pentose-utilizing strains for bioethanol production.

Results

Using LC-MS/MS we determined the dynamics in the concentrations of intracellular metabolites in central carbon metabolism, nine amino acids, the purine nucleotides and redox cofactors. The general response to the transition from glucose to xylose was increased concentrations of amino acids and TCA-cycle intermediates, and decreased concentrations of sugar phosphates and redox cofactors. The two strains investigated had significantly different uptake rates of xylose which led to an enhanced response in the XI-strain. Despite the difference in xylose uptake rate, the adenylate energy charge remained high and stable around 0.8 in both strains. In contrast to the adenylate pool, large changes were observed in the guanylate pool.

Conclusions

The low uptake of xylose by the XI-strain led to several distinguished responses: depletion of key metabolites in glycolysis and NADPH, a reduced GTP/GDP ratio and accumulation of PEP and aromatic amino acids. These changes are strong indicators of carbon starvation. The XR/XDH-strain displayed few such traits. The coexistence of these traits and a stable adenylate charge indicates that xylose supplies energy to the cells but does not suppress a response similar to carbon starvation. Particular signals may play a role in the latter, of which the GTP/GMP ratio could be a candidate as it decreased significantly in both strains.

【 授权许可】

   
2012 Bergdahl et al.; licensee BioMed Central Ltd.

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【 参考文献 】
  • [1]Nevoigt E: Progress in metabolic engineering ofSaccharomyces cerevisiae. Microbiol Mol Biol Rev 2008, 72:379-412.
  • [2]Lin Y, Tanaka S: Ethanol fermentation from biomass resources: Current state and prospects. Appl Microbiol Biotechnol 2006, 69:627-642.
  • [3]Wiselogel AE, Agblevor FA, Johnson DK, Deutch S, Fennell JA, Sanderson MA: Compositional changes during storage of large round switchgrass bales. Bioresour Technol 1996, 56:103-109.
  • [4]Perez DD, Guillemain A, Berthelot A, N'Guyen-The N, De Morogues F, Gomes C: Evaluation of forestry biomass quality for the production of second-generation biofuels. Cell Chem Technol 2010, 44:1-14.
  • [5]Sassner P, Galbe M, Zacchi G: Techno-economic evaluation of bioethanol production from three different lignocellulosic materials. Biomass Bioenerg 2008, 32:422-430.
  • [6]Van Vleet JH, Jeffries TW: Yeast metabolic engineering for hemicellulosic ethanol production. Curr Opin Biotechnol 2009, 20:300-306.
  • [7]Matsushika A, Inoue H, Kodaki T, Sawayama S: Ethanol production from xylose in engineeredSaccharomyces cerevisiaestrains: Current state and perspectives. Appl Microbiol Biotechnol 2009, 84:37-53.
  • [8]Hahn-Hagerdal B, Karhumaa K, Fonseca C, Spencer-Martins I, Gorwa-Grauslund MF: Towards industrial pentose-fermenting yeast strains. Appl Microbiol Biotechnol 2007, 74:937-953.
  • [9]Kern A, Tilley E, Hunter IS, Legisa M, Glieder A: Engineering primary metabolic pathways of industrial micro-organisms. J Biotechnol 2007, 129:6-29.
  • [10]Karhumaa K, Sanchez RG, Hahn-Hagerdal B, Gorwa-Grauslund MF: Comparison of the xylose reductase-xylitol dehydrogenase and the xylose isomerase pathways for xylose fermentation by recombinantSaccharomyces cerevisiae. Microb Cell Fact 2007, 6:5. BioMed Central Full Text
  • [11]Bengtsson O: Genetic traits beneficial for xylose utilization by recombinantSaccharomyces cerevisiae.Doctoral Thesis. Lund University, Division of Applied Microbiology 2008.
  • [12]Bruinenberg PM, de Bot PHM, van Dijken JP, Scheffers WA: NADH-linked aldose reductase - the key to anaerobic alcoholic fermentation of xylose by yeasts. Appl Microbiol Biotechnol 1984, 19:256-260.
  • [13]Bruinenberg PM, de Bot PHM, van Dijken JP, Scheffers WA: The role of redox balances in the anaerobic fermentation of xylose by yeasts. Appl Microbiol Biotechnol 1983, 18:287-292.
  • [14]Kotter P, Ciriacy M: Xylose fermentation bySaccharomyces cerevisiae. Appl Microbiol Biotechnol 1993, 38:776-783.
  • [15]van Maris AJA, Winkler AA, Kuyper M, de Laat W, van Dijken JP, Pronk JT: Development of efficient xylose fermentation inSaccharomyces cerevisiae: Xylose lsomerase as a key component. In Biofuels. Edited by Olsson L. Springer-Verlag Berlin, Berlin; 2007:179-204. [Scheper T (Series Editor): Advances in Biochemical Engineering/Biotechnology, vol 108.]
  • [16]Smedsgaard J, Nielsen J: Metabolite profiling of fungi and yeast: from phenotype to metabolome by MS and informatics. J Exp Bot 2005, 56:273-286.
  • [17]Delneri D, Brancia FL, Oliver SG: Towards a truly integrative biology through the functional genomics of yeast. Curr Opin Biotechnol 2001, 12:87-91.
  • [18]Heinemann M, Sauer U: Systems biology of microbial metabolism. Curr Opin Microbiol 2010, 13:337-343.
  • [19]Gerosa L, Sauer U: Regulation and control of metabolic fluxes in microbes. Curr Opin Biotechnol 2011, 22:566-575.
  • [20]Buescher JM, Moco S, Sauer U, Zamboni N: Ultrahigh performance liquid chromatography-tandem mass spectrometry method for fast and robust quantification of anionic and aromatic metabolites. Anal Chem 2010, 82:4403-4412.
  • [21]Karhumaa K, Hahn-Hägerdal B, Gorwa-Grauslund MF: Investigation of limiting metabolic steps in the utilization of xylose by recombinantSaccharomyces cerevisiaeusing metabolic engineering. Yeast 2005, 22:359-368.
  • [22]Parachin NS, Bergdahl B, van Niel EWJ, Gorwa-Grauslund MF: Kinetic modeling reveals current limitations in the production of ethanol from xylose by recombinantSaccharomyces cerevisiae. Metab Eng 2011, 13:508-517.
  • [23]Zamboni N, Kummel A, Heinemann M, anNET: A tool for network-embedded thermodynamic analysis of quantitative metabolome data. BMC Bioinformatics 2008, 9:199. BioMed Central Full Text
  • [24]Runquist D, Hahn-Hagerdal B, Bettiga M: Increased expression of the oxidative pentose phosphate pathway and gluconeogenesis in anaerobically growing xylose-utilizingSaccharomyces cerevisiae. Microb Cell Fact 2009, 8:49. BioMed Central Full Text
  • [25]de Koning W, van Dam K: A method for the determination of changes of glycolytic metabolites in yeast on a subsecond time scale using extraction at neutral pH. Anal Biochem 1992, 204:118-123.
  • [26]Zamboni N, Kummel A, Heinemann M: anNET: A tool for networkembedded thermodynamic analysis of quantitative metabolome data. BMC Bioinformatics 2008, 9:199. BioMed Central Full Text
  • [27]Mo M, Palsson B, Herrgard M: Connecting extracellular metabolomic measurements to intracellular flux states in yeast. BMC Syst Biol 2009, 3:37. BioMed Central Full Text
  • [28]Becker SA, Feist AM, Mo ML, Hannum G, Palsson BO, Herrgard MJ: Quantitative prediction of cellular metabolism with constraint-based models: the COBRA Toolbox. Nat Protocols 2007, 2:727-738.
  • [29]Wahlbom CF, Eliasson A, Hahn-Hägerdal B: Intracellular fluxes in a recombinant xylose-utilizingSaccharomyces cerevisiaecultivated anaerobically at different dilution rates and feed concentrations. Biotechnol Bioeng 2001, 72:289-296.
  • [30]Snitkin E, Dudley A, Janse D, Wong K, Church G, Segre D: Model-driven analysis of experimentally determined growth phenotypes for 465 yeast gene deletion mutants under 16 different conditions. Genome Biol 2008, 9:R140. BioMed Central Full Text
  • [31]Jankowski MD, Henry CS, Broadbelt LJ, Hatzimanikatis V: Group contribution method for thermodynamic analysis of complex metabolic networks. Biophys J 2008, 95:1487-1499.
  • [32]Klimacek M, Krahulec S, Sauer U, Nidetzky B: Limitations in xylosefermentingSaccharomyces cerevisiae, made evident through comprehensive metabolite profiling and thermodynamic analysis. Appl Environ Microbiol 2010, 76:7566-7574.
  • [33]Cipollina C, ten Pierick A, Canelas AB, Seifar RM, van Maris AJA, van Dam JC, Heijnen JJ: A comprehensive method for the quantification of the nonoxidative pentose phosphate pathway intermediates inSaccharomyces cerevisiaeby GC-IDMS. J Chromatogr B 2009, 877:3231-3236.
  • [34]Hynne F, Dano S, Sorensen PG: Full-scale model of glycolysis inSaccharomyces cerevisiae. Biophys Chem 2001, 94:121-163.
  • [35]Altintas MM, Eddy CK, Zhang M, McMillan JD, Kompala DS: Kinetic modeling to optimize pentose fermentation inZymomonas mobilis. Biotechnol Bioeng 2006, 94:273-295.
  • [36]Ball WJ, Atkinson DE: Adenylate energy charge inSaccharomyces cerevisiaeduring starvation. J Bacteriol 1975, 121:975-982.
  • [37]Klimacek M, Krahulec S, Sauer U, Nidetzky B: Limitations in xylose-fermentingSaccharomyces cerevisiae, made evident through comprehensive metabolite profiling and thermodynamic analysis. Appl Environ Microbiol 2010, 76:7566-7574.
  • [38]Wisselink HW, Cipollina C, Oud B, Crimi B, Heijnen JJ, Pronk JT, van Maris AJA: Metabolome, transcriptome and metabolic flux analysis of arabinose fermentation by engineeredSaccharomyces cerevisiae. Metab Eng 2010, 12:537-551.
  • [39]Karhumaa K, Fromanger R, Hahn-Hagerdal B, Gorwa-Grauslund MF: High activity of xylose reductase and xylitol dehydrogenase improves xylose fermentation by recombinantSaccharomyces cerevisiae. Appl Microbiol Biotechnol 2007, 73:1039-1046.
  • [40]Kuyper M, Toirkens MJ, Diderich JA, Winkler AA, van Dijken JP, Pronk JT: Evolutionary engineering of mixed-sugar utilization by a xylose-fermenting Saccharomyces cerevisiae strain. Fems Yeast Research 2005, 5:925-934.
  • [41]Sedlak M, Ho NWY: Characterization of the effectiveness of hexose transporters for transporting xylose during glucose and xylose co-fermentation by a recombinant Saccharomyces yeast. Yeast 2004, 21:671-684.
  • [42]Saloheimo A, Rauta J, Stasyk OV, Sibirny AA, Penttila M, Ruohonen L: Xylose transport studies with xylose-utilizing Saccharomyces cerevisiae strains expressing heterologous and homologous permeases. Appl Microbiol Biotechnol 2007, 74:1041-1052.
  • [43]Fonseca C, Olofsson K, Ferreira C, Runquist D, Fonseca LL, Hahn-Hagerdal B, Liden G: The glucose/xylose facilitator Gxf1 fromCandida intermediaexpressed in a xylose-fermenting industrial strain ofSaccharomyces cerevisiaeincreases xylose uptake in SSCF of wheat straw. Enzyme Microb Technol 2011, 48:518-525.
  • [44]Stephanopoulos G, Aristidou A, Nielsen J: Metabolic Engineering: Principles and Methodologies. Elsevier Academic Press, San Diego, CA, USA; 1998.
  • [45]Frick O, Wittmann C: Characterization of the metabolic shift between oxidative and fermentative growth inSaccharomyces cerevisiaeby comparative C-13 flux analysis. Microb Cell Fact 2005, 4:30. BioMed Central Full Text
  • [46]Gancedo JM, Lagunas R: Contribution of the pentose-phosphate pathway to glucose metabolism inSaccharomyces cerevisiae: A critical analysis on the use of labelled glucose. Plant Science Letters 1973, 1:193-200.
  • [47]Maaheimo H, Fiaux J, Çakar ZP, Bailey JE, Sauer U, Szyperski T: Central carbon metabolism ofSaccharomyces cerevisiaeexplored by biosynthetic fractional13C labeling of common amino acids. Eur J Biochem 2001, 268:2464-2479.
  • [48]Senac T, Hahn-Hägerdal B: Intermediary metabolite concentrations in xylulose-fermenting and glucose-fermentingSaccharomyces cerevisiaecells. Appl Environ Microbiol 1990, 56:120-126.
  • [49]Johansson B, Hahn-Hagerdal B: The non-oxidative pentose phosphate pathway controls the fermentation rate of xylulose but not of xylose inSaccharomyces cerevisiaeTMB3001. Fems Yeast Research 2002, 2:277-282.
  • [50]Chu BCH, Lee H: Genetic improvement ofSaccharomyces cerevisiaefor xylose fermentation. Biotechnol Adv 2007, 25:425-441.
  • [51]Evans PR, Farrants GW, Hudson PJ: Phosphofructokinase - structure and control. Philos Trans R Soc Lond B Biol Sci 1981, 293:53-62.
  • [52]Brauer MJ, Yuan J, Bennett BD, Lu W, Kimball E, Botstein D, Rabinowitz JD: Conservation of the metabolomic response to starvation across two divergent microbes. Proc Natl Acad Sci USA 2006, 103:19302-19307.
  • [53]Walther T, Novo M, Roessger K, Letisse F, Loret M-O, Portais J-C, Francois J-M: Control of ATP homeostasis during the respiro-fermentative transition in yeast. Mol Syst Biol 2010, 6:344.
  • [54]Kresnowati MTAP, van Winden WA, Almering MJH, ten Pierick A, Ras C, Knijnenburg TA, Daran-Lapujade P, Pronk JT, Heijnen JJ, Daran JM: When transcriptome meets metabolome: fast cellular responses of yeast to sudden relief of glucose limitation. Mol Syst Biol 2006, 2:49.
  • [55]Boles E, Zimmermann FK, Heinisch J: Different signals control the activation of glycolysis in the yeastSaccharomyces cerevisiae. Yeast 1993, 9:761-770.
  • [56]Mueller S, Boles E, May M, Zimmermann FK: Different internal metabolites trigger the induction of glycolytic gene expression in Saccharomyces cerevisiae. J Bacteriol 1995, 177:4517-4519.
  • [57]Barwell CJ, Woodward B, Brunt RV: Regulation of pyruvate kinase by fructose 1,6-diphosphate inSaccharomyces cerevisiae. Eur J Biochem 1971, 18:59-64.
  • [58]Gad A: Stimulation of yeast phosphofructokinase activity by Fructose 2,6-bisphosphate. Biochem Biophys Res Commun 1981, 102:985-991.
  • [59]Francois J, Vanschaftingen E, Hers HG: The mechanism by which glucose increases fructose 2,6-bisphosphate concentration inSaccharomyces cerevisiae- A cyclic-AMP-dependent activation of phosphofructokinase-2. Eur J Biochem 1984, 145:187-193.
  • [60]Busti S, Coccetti P, Alberghina L, Vanoni M: Glucose signaling-mediated coordination of cell growth and cell cycle inSaccharomyces cerevisiae. Sensors 2010, 10:6195-6240.
  • [61]Jeffries TW, Fady JH, Lightfoot EN: Effect of glucose supplements on the fermentation of xylose byPachysolen tannophilus. Biotechnology and Bioengineering 1985, 27:171-176.
  • [62]Ohgren K, Bengtsson O, Gorwa-Grauslund MF, Galbe M, Hahn-Hagerdal B, Zacchi G: Simultaneous saccharification and co-fermentation of glucose and xylose in steam-pretreated corn stover at high fiber content withSaccharomyces cerevisiaeTMB3400. Journal of Biotechnology 2006, 126:488-498.
  • [63]Krahulec S, Petschacher B, Wallner M, Longus K, Klimacek M, Nidetzky B: Fermentation of mixed glucose-xylose substrates by engineered strains ofSaccharomyces cerevisiae: Role of the coenzyme specificity of xylose reductase, and effect of glucose on xylose utilization. Microb Cell Fact 2010, 10:9-16.
  • [64]Braus GH: Aromatic amino acid biosynthesis in the yeastSaccharomyces-cerevisiae- a model system for the regulation of a eukaryotic biosynthetic pathway. Microbiol Rev 1991, 55:349-370.
  • [65]Mauricio JC, Pareja M, Ortega JM: Changes in the intracellular concentrations of the adenosine phosphates and nicotinamide adenine dinucleotides ofSaccharomyces cerevisiaeduring batch fermentation. World J Microbiol Biotechnol 1995, 11:196-201.
  • [66]Salusjarvi L, Pitkanen JP, Aristidou A, Ruohonen L, Penttila M: Transcription analysis of recombinantSaccharomyces cerevisiaereveals novel responses to xylose. Appl Biochem Biotechnol 2006, 128:237-261.
  • [67]Wahlbom CF, Hahn-Hagerdal B: Furfural, 5-hydroxymethyl furfural, and acetoin act as external electron acceptors during anaerobic fermentation of xylose in recombinantSaccharomyces cerevisiae. Biotechnol Bioeng 2002, 78:172-178.
  • [68]Wahlbom CF, Otero RRC, van Zyl WH, Hahn-Hagerdal B, Jonsson LJ: Molecular analysis of aSaccharomyces cerevisiaemutant with improved ability to utilize xylose shows enhanced expression of proteins involved in transport, initial xylose metabolism, and the pentose phosphate pathway. Appl Environ Microbiol 2003, 69:740-746.
  • [69]Jin YS, Laplaza JM, Jeffries TW: Saccharomyces cerevisiaeengineered for xylose metabolism exhibits a respiratory response. Appl Environ Microbiol 2004, 70:6816-6825.
  • [70]Camarasa C, Grivet JP, Dequin S: Investigation by 13C-NMR and tricarboxylic acid (TCA) deletion mutant analysis of pathways for succinate formation inSaccharomyces cerevisiaeduring anaerobic fermentation. Microbiology 2003, 149:2669-2678.
  • [71]Minard KI, McAlisterhenn L: Glucose-induced degradation of the MDH2 isozyme of malate dehydrogenase in yeast. J Biol Chem 1992, 267:17458-17464.
  • [72]Atkinson DE: Energy charge of adenylate pool as a regulatory parameter. Interaction with feedback modifiers. Biochemistry 1968, 7:4030-4034.
  • [73]Dombek KM, Ingram LO: Intracellular accumulation of AMP as a cause for the decline in rate of ethanol-production bySaccharomyces cerevisiaeduring batch fermentation. Appl Environ Microbiol 1988, 54:98-104.
  • [74]Knowles CJ: Microbial metabolic regulation by adenine nucleotide pools. In Microbial Energetics: Twenty-Seventh Symposium of the Society for General Microbiology. Edited by Haddock BA, Hamilton WA. Cambridge University Press, Cambridge; 1977:241-283.
  • [75]Chapman AG, Atkinson DE: Adenine nucleotide concentrations and turnover rates. Their correlation with biological activity in bacteria and yeast. In Advances in microbial physiology. Edited by Rose AH, Tempest DW. Academic Press, London; 1977:253-306.
  • [76]Johnston GC, Ehrhardt CW, Lorincz A, Carter BLA: Regulation of cell-size in the yeastSacchaormyces cerevisiae. J Bacteriol 1979, 137:1-5.
  • [77]Moore SA: Kinetic evidence for a critical rate of protein synthesis in theSaccharomyces cerevisiaeyeast cell cycle. J Biol Chem 1988, 263:9674-9681.
  • [78]Rudoni S, Colombo S, Coccetti P, Martegani E: Role of guanine nucleotides in the regulation of the Ras/cAMP pathway inSaccharomyces cerevisiae. BBA Mol Cell Res 2001, 1538:181-189.
  • [79]Iglesias-Gato D, Martin-Marcos P, Santos MA, Hinnebusch AG, Tamame M: Guanine nucleotide pool imbalance impairs multiple steps of protein synthesis and disrupts GCN4 translational control inSaccharomyces cerevisiae. Genetics 2011, 187:105-122.
  • [80]Yalowitz JA, Jayaram HN: Molecular targets of guanine nucleotides in differentiation, proliferation and apoptosis. Anticancer Res 2000, 20:2329-2338.
  • [81]Toda T, Uno I, Ishikawa T, Powers S, Kataoka T, Broek D, Cameron S, Broach J, Matsumoto K, Wigler M: In yeast, Ras proteins are controlling elements of adenylate cyclase. Cell 1985, 40:27-36.
  • [82]Thevelein JM: The Ras-adenylate cyclase pathway and cell cycle control inSaccharomyces cerevisiae. Antonie Van Leeuwenhoek 1992, 62:109-130.
  • [83]Kapp LD, Lorsch JR: The molecular mechanics of eukaryotic translation. Annu Rev Biochem 2004, 73:657-704.
  • [84]Cherkasova V, Qiu H, Hinnebusch AG: Snf1 promotes phosphorylation of the alpha subunit of eukaryotic translation initiation factor 2 by activating Gcn2 and inhibiting phosphatases Glc7 and Sit4. Molecular and Cellular Biology 2010, 30:2862-2873.
  • [85]Henderson JF, Paterson ARP: Nucleotide metabolism: an introduction. Academic Press, New York; 1973.
  • [86]Thompson FM, Atkinson DE: Response of nucleoside diphosphate kinase to adenylate energy charge. Biochem Biophys Res Commun 1971, 45:1581.
  • [87]Varma A, Freese EB, Freese E: Partial deprivation of GTP initiates meiosis and sporulation inSaccharomyces cerevisiae. Mol Gen Genet 1985, 201:1-6.
  • [88]Breton A, Pinson B, Coulpier F, Giraud MF, Dautant A, Daignan-Fornier B: Lethal accumulation of guanylic nucleotides inSaccharomyces cerevisiaeHPT1-deregulated mutants. Genetics 2008, 178:815-824.
  • [89]Saint-Marc C, Pinson B, Coulpier F, Jourdren L, Lisova O, Daignan-Fornier B: Phenotypic consequences of purine nucleotide imbalance inSaccharomyces cerevisiae. Genetics 2009, 183:529-538.
  • [90]Gonzalez B, Francois J, Renaud M: A rapid and reliable method for metabolite extraction in yeast using boiling buffered ethanol. Yeast 1997, 13:1347-1355.
  • [91]Miller JN, Miller JC: Statistics and Chemometrics for Analytical Chemistry. 5th edition. Pearson Education Limited, Harlow; 2005.
  • [92]Rousseeuw PJ: Tutorial to robust statistics. J Chemometr 1991, 5:1-20.
  • [93]Ortiz MC, Sarabia LA, Herrero A: Robust regression techniques - A useful alternative for the detection of outlier data in chemical analysis. Talanta 2006, 70:499-512.
  • [94]Scholz M, Selbig J: Visualization and analysis of molecular data. In Metabolomics. Humana Press, Totowa, USA; 2007:87-104. [Walker JM (Series Editor): Methods in Molecular Biology, vol 358.]
  • [95]Jolliffe IT: Principal component analysis. 2nd edition. Springer-Verlag, New York; 2002.
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