Abstract
The well defined genetic architecture and metabolic network of Saccharomycescerevisiae make this organism a cornerstone for metabolomics research. Recent effortshave focused on robust sample preparation techniques, analytical tools to quantitatively identifyhundreds of metabolites at the same time, and elegant approaches for analyzing and interpreting thedata. While equally important, we focus here on approaches for extracting useful information fromthe data itself. We outline several statistical and mathematical methods that can be used to digestand validate the most important features in the data. These multivariate approaches are from eitherthe well established standard portfolio of statistical methods, or can be adapted from other areaswhere similar problems can be identified and where statistical and mathematical methods exist. Lookingforward, we also describe approaches for fusing metabolome data with other cellular measurements andnetwork structure to elucidate biosynthetic control mechanisms.
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References
Allen J, Davey HM, Broadhurst D, Heald JK, Rowland JJ, Oliver SG, Kell DB (2003) High-throughput classification of yeast mutants for functional genomics using metabolic footprinting. Nat Biotechnol 21:692–696
Alper H, Miyaoku K, Stephanopoulos G (2005) Construction of lycopene-overproducing E. coli strains by combining systematic and combinatorial gene knockout targets. Nat Biotechnol 23:612–616
Anderberg MR (1973) Cluster Analysis for Applications. Academic Press, New York, NY
Antoniou A (1993) Digital Filters: Analysis, Design, and Applications. McGraw-Hill, New York NY
Bartlett MS (1937) The statistical conception of mental factors. Br J Psychol 28:97–104
Brown M, Dunn WB, Ellis DI, Goodacre R, Handl J, Knowles JD, O'Hagan S, Spasiæ I, Kell DB (2005) A metabolome pipeline: from concept to data to knowledge. Metabolomics 1:39–51
Bylund D, Danielsson R, Malmquist G, Markides KE (2002) Chromatographic alignment by warping and dynamic programming as a pre-processing tool for PARAFAC modelling of liquid chromatography-mass spectrometry data. J Chromatogr A 961:237–244
Cai T, Zhang D, Ben-Amotz D (2001) Enhanced chemical classification of Raman images using multiresolution wavelet transformation. Appl Spectrosc 55:1124–1130
Çakir T, Patil KR, Onsan ZI, Ulgen KO, Kirdar B, Nielsen J (2006) Integration of metabolome data with metabolic networks reveals reporter reactions Mol Sys Biol 2:0050 doi:10.1038/msb4100085
Cameron DC, Altaras NE, Hoffman ML, Shaw AJ (1998) Metabolic engineering of propanediol pathways. Biotechnol Prog 14:116–125
Castrillo JI, Hayes A, Mohammed S, Gaskell SJ, Oliver SG (2003) An optimized protocol for metabolome analysis in yeast using direct infusion electrospray mass spectrometry. Phytochemistry 62:929–937
Castrillo JI, Oliver SG (2004) Yeast as a touchstone in post-genomic research: strategies for integrative analysis in functional genomics. J Biochem Mol Biol 37:93–106
Depczynski U, Jetter K, Molt K, Niemöller A (1997) The fast wavelet transform on compact intervals as a tool in chemometrics. I. Mathematical background. Chemom Intell Lab Syst 39:19–27
Dromey RG, Stefik MJ, Rindfleisch TC, Duffield AM (1976) Extraction of mass spectra free of background and neighboring component contributions from gas chromatography/mass spectrometry data. Anal Chem 48:1368–1375
Duda RO, Hart PE, Stork DG (2001) Pattern Classification. Wiley, ISBN 0471056693
Eilers PHC (2003) A perfect smoother. Anal Chem 75:3631–3636
Eilers PHC (2004) Parametric time warping. Anal Chem 76:404–411
Endy D (2005) Foundations for engineering biology. Nature 438:449–453
Fiehn O (2002) Metabolomics: the link between genotypes and phenotypes. Plant Mol Biol 48:155–171
Fiehn O, Weckwerth W (2003) Deciphering metabolic networks. Eur J Biochem 270:579–588
Fisher RA (1936) The use of multiple measures in taxonomic problems. Ann Eugenics 7:179–188
Fix E, Hodges JL (1951) Discriminatory analysis, nonparametric discrimination: Consistency properties. Technical Report Technical Report 4. USAF School of Aviation Medicine, Randolph Field TX
Forshed J, Schuppe-Koistinen I, Jacobsson SP (2003) Peak alignment of NMR signals by means of a genetic algorithm. Analytica Chimica Acta 487:189–199
Forster J, Famili I, Fu P, Palsson BO, Nielsen J (2003) Genome-scale reconstruction of the Saccharomyces cerevisiae metabolic network. Genome Res 13:244–253
Friedman JH, Stuetzle W (1981) Projection pursuit regression. J American Stat Assoc 76:817–823
Frisvad JC, Filtenborg O (1983) Classification of terverticillate penicillia based on profiles of mycotoxins and other secondary metabolites. Appl Environ Microbiol 46:1301–1310
Fung E, Wong WW, Suen JK, Bulter T, Lee SG, Liao JC (2005) A synthetic gene-metabolic oscillator. Nature 435:118–122
Giaever G, Chu AM, Ni L, Connelly C, Riles L, Veronneau S, Dow S, Lucau-Danila A, Anderson K, Andre B, Arkin AP, Astromoff A, El Bakkoury M, Bangham R, Benito R, Brachat S, Campanaro S, Curtiss M, Davis K, Deutschbauer A, Entian KD, Flaherty P, Foury F, Garfinkel DJ, Gerstein M, Gotte D, Guldener U, Hegemann JH, Hempel S, Herman Z, Jaramillo DF, Kelly DE, Kelly SL, Kotter P, LaBonte D, Lamb DC, Lan N, Liang H, Liao H, Liu L, Luo CY, Lussier M, Mao R, Menard P, Ooi SL, Revuelta JL, Roberts CJ, Rose M, Ross-Macdonald P, Scherens B, Schimmack G, Shafer B, Shoemaker DD, Sookhai-Mahadeo S, Storms RK, Strathern JN, Valle G, Voet M, Volckaert G, Wang CY, Ward TR, Wilhelmy J, Winzeler EA, Yang YH, Yen G, Youngman E, Yu KX, Bussey H, Boeke JD, Snyder M, Philippsen P, Davis RW, Johnston M (2002) Functional profiling of the Saccharomyces cerevisiae genome. Nature 418:387–391
Gilbert RJ, Goodacre R, Woodward AM, Kell DB (1997) Genetic programming: A novel method for the quantitative analysis of pyrolysis mass spectral data. Anal Chem 69:4381–4389
Goeddel DV, Kleid DG, Bolivar F, Heyneker HL, Yansura DG, Crea R, Hirose T, Kraszewski A, Itakura K, Riggs AD (1979) Expression in Escherichia coli of chemically synthesized genes for human insulin. Proc Natl Acad Sci USA 76:106–110
Goehner R (1978) Background subtract subroutine for spectral data. Anal Chem 50:1223–1225
Goffeau A, Barrell BG, Bussey H, Davis RW, Dujon B, Feldmann H, Galibert F, Hoheisel JD, Jacq C, Johnston M, Louis EJ, Mewes HW, Murakami Y, Philippsen P, Tettelin H, Oliver SG (1996) Life with 6000 genes. Science 274:546, 563–547
Gonzalez B, Francois J, Renaud M (1997) A Rapid and reliable method for metabolite extraction in yeast using boiling buffered ethanol. Yeast 13:1347–1356
Goodacre R, Vaidyanathan S, Dunn WB, Harrigan GG, Kell DB (2004) Metabolomics by numbers: acquiring and understanding global metabolite data. Trends Biotechnol 22:245–252
Grung B, Kvalheim OM (1995) Retention time adjustments of two-way chromatograms using Bessel's inequality. Anal Chim Acta 304:57–66
Hansen ME, Smedsgaard J (2004) A new matching algorithm for high resolution mass spectra. J Am Soc Mass Spectrom 15:1173–1180
Hansen ME, Smedsgaard J (2006) Automated work-flow for processing of high-resolution mass spectra from direct infusion fingerprinting. Metabolomics, (Submitted)
Hartigan J (1975) Clustering Algorithms. Wiley, New York NY
Hayes A, Zhang N, Wu J, Butler PR, Hauser NC, Hoheisel JD, Lim FL, Sharrocks AD, Oliver SG (2002) Hybridization array technology coupled with chemostat culture: Tools to interrogate gene expression in Saccharomyces cerevisiae. Methods 26:281–290
Herbrich R (2001) Learning Kernel Classifiers: Theory and Algorithms. MIT Press, ISBN 026208306X
Hertz HS, Hites RA, Biemann K (1971) Identification of mass spectra by computer searching a file of known spectra. Anal Chem 43:681–691
Hood L, Heath JR, Phelps ME, Lin B (2004) Systems biology and new technologies enable predictive and preventative medicine. Science 306:640–643
Isaacs FJ, Dwyer DJ, Collins JJ (2006) RNA synthetic biology. Nat Biotechnol 24:545–554
Ideker T, Thorsson V, Ranish JA, Christmas R, Buhler J, Eng JK, Bumgarner R, Goodlett DR, Aebersold R, Hood L (2001) Integrated genomic and proteomic analyses of a systematically perturbed metabolic network. Science 292:929–934
Jewett MC, Hofmann G, Nielsen J (2006) Fungal metabolite analysis in genomics and phenomics. Curr Opin Biotechnol 17:191–197
Johnson KJ, Wright BW, Jarman KH, Synoveca RE (2003) High-speed peak matching algorithm for retention time alignment of gas chromatographic data for chemometric analysis. J Chromatogr A 996:141–155
Karhunen J, Joutsensalo J (1995) Generalization of principal component analysis, optimization problems, and neural networks. Neural Netw 8:549–562
Kassidas A, MacGregor JF, Taylor PA (1998) Synchronization of batch trajectories using dynamic time warping. Amer Inst Chem Eng J 44:864–873
Kaufman L, Rousseeuw PJ (1990) Finding Groups in Data. Wiley
Kell DB, Darby RM, Draper J (2001) Genomic Computing. Explanatory Analysis of Plant Expression Profiling Data Using Machine Learning. Plant Phys 126:943–951
Kell DB (2002) Metabolomics and machine learning: explanatory analysis of complex metabolome data using genetic programming to produce simple, robust rules. Mol Biol Rep 29:237–241
Kell DB (2004) Metabolomics and systems biology: making sense of the soup. Curr Opin Microbiol 7:296–307
Kong H, Ye F, Lu X, Guo L, Tian J, Xu G (2005) Deconvolution of overlapped peaks based on the exponentially modified Gaussian model in comprehensive two-dimensional gas chromatography. Journal of Chromatography A 1086:160–164
de Koning W, van Dam K (1992) A method for the determination of changes of glycolytic metabolites in yeast on a subsecond time scale using extraction at neutral pH. Anal Biochem 204:118–123
Koza JR (1992) Genetic Programming: On the Programming of Computers by Means of Natural Selection. MIT Press, Cambridge, MA
Koza JR (1994) Genetic Programming II: Automatic Discovery of Reusable Programs. MIT Press, Cambridge, MA
Kümmel A, Panke S, Heinemann M (2006) Putative regulatory sites unraveled by network-embedded thermodynamic analysis of metabolome data. Mol Syst Biol 2:0034 doi:10.1038/msb4100074
Lafaye A, Labarre J, Tabet JC, Ezan E, Junot C (2005) Liquid chromatography-mass spectrometry and 15N metabolic labeling for quantitative metabolic profiling. Anal Chem 77:2026–2033
Lange HC, Eman M, van Zuijlen G, Visser D, van Dam JC, Frank J, de Mattos MJ, Heijnen JJ (2001) Improved rapid sampling for in vivo kinetics of intracellular metabolites in Saccharomyces cerevisiae. Biotechnol Bioeng 75:406–415
Lee TI, Rinaldi NJ, Robert F, Odom DT, Bar-Joseph Z, Gerber GK, Hannett NM, Harbison CT, Thompson CM, Simon I, Zeitlinger J, Jennings EG, Murray HL, Gordon DB, Ren B, Wyrick JJ, Tagne JB, Volkert TL, Fraenkel E, Gifford DK, Young RA (2002) Transcriptional regulatory networks in Saccharomyces cerevisiae. Science 298:799–804
Li J (2002) Comparison of the capability of peak functions in describing real chromatographic peaks. Journal of Chromatography A 952:63–70
Listgarten J, Nealy RM, Roweis ST, Emili A (2004) Multiple Alignment of Continuous Time Series. Advances in Neural Information Processing Systems 17. MIT Press, Cambridge, MA
Liu B, Sera Y, Matsubara N, Otsuka K, Terabe S (2003) Signal denoising and baseline correction by discrete wavelet transform for microchip capillary electrophoresis. Electrophoresis 24:3260–3265
MacQueen J (1966) Some methods for classification and analysis of multivariate observations. Proc Fifth Berkeley Symp University of California Press 1:281–297
Mager WH, Winderickx J (2005) Yeast as a model for medical and medicinal research. Trends Pharmacol Sci 26:265–273
Maleknia SD, Downard KM (2005) Charge ratio analysis method: approach for the deconvolution of electrospray mass spectra. Anal Chem 77:111–119
Malmquist G, Danielsson R (1994) Alignment of chromatographic profiles for principal component analysis: a prerequisite for fingerprinting methods. J Chromatogr A 687:71–88
Mardia KV, Kent JT, Bibby JM (1979) Multivariate Analysis. Academic Press, London
Mas S, Villas-Bôas SG, Hansen ME, Akesson M, Nielsen J (2006) A comparison of direct infusion MS and GC-MS for metabolic footprinting of yeast mutants. Biotechnol Bioeng, in press
Mashego MR, Wu L, Van Dam JC, Ras C, Vinke JL, Van Winden WA, Van Gulik WM, Heijnen JJ (2004) MIRACLE: mass isotopomer ratio analysis of U-13C-labeled extracts. A new method for accurate quantification of changes in concentrations of intracellular metabolites. Biotechnol Bioeng 85:620–628
Mashego MR, van Gulik WM, Vinke JL, Visser D, Heijnen JJ (2006) In vivo kinetics with rapid perturbation experiments in Saccharomyces cerevisiae using a second-generation BioScope. Metab Eng 8:370–383
Mazet V, Carteret C, Briea D, Idier J, Humbert B (2005) Background removal from spectra by designing and minimizing a non-quadratic cost function. Chemom Intell Lab Syst 76:121–133
McLafferty FW (1974) Probability based matching of mass spectra. Org Mass Spectrom 9:690–702
Mendes P (2002) Emerging bioinformatics for the metabolome. Brief Bioinform 3:134–145
Mitra SK (1998) Digital Signal Processing: A Computer-Based Approach. McGraw-Hill, New York NY
Nielsen J (2003) It is all about metabolic fluxes. J Bacteriol 185:7031–7035
Nielsen J, Oliver S (2005) The next wave in metabolome analysis. Trends Biotechnol 23:544–546
Nielsen NV, Carstensen JM, Smedsgaard J (1998) Aligning of single and multiple wavelength chromatographic profiles for chemometric data analysis using correlation optimized warping. J Chromatogr A 805:17–35
Patil KR, Nielsen J (2005) Uncovering transcriptional regulation of metabolism by using metabolic network topology. Proc Natl Acad Sci USA 102:2685–2689
Pearson K (1901) On Lines and Planes of Closest Fit to Systems of Points in Space. Phil Mag 2:559–572
Percival DB, Walden AT (2000) Wavelet Methods for Time Series Analysis. Cambridge University Press, Cambridge MA
Pir P, Kirdar B, Hayes A, Onsan ZY, Ulgen KO, Oliver SG (2006) Integrative investigation of metabolic and transcriptomic data. BMC Bioinformatics 7:203
Porro D, Sauer M, Branduardi P, Mattanovich D (2005) Recombinant protein production in yeasts. Mol Biotechnol 31:245–259
Pravdova V, Walczak B, Massart DL (2002) A comparison of two algorithms for warping of analytical signals. Anal Chim Acta 456:77–92
Raamsdonk LM, Teusink B, Broadhurst D, Zhang N, Hayes A, Walsh MC, Berden JA, Brindle KM, Kell DB, Rowland JJ, Westerhoff HV, Dam KV, Oliver SG (2001) A functional genomics strategy that uses metabolome data to reveal the phenotype of silent mutations. Nat Biotechnol 19:45–50
Ro DK, Paradise EM, Ouellet M, Fisher KJ, Newman KL, Ndungu JM, Ho KA, Eachus RA, Ham TS, Kirby J, Chang MC, Withers ST, Shiba Y, Sarpong R, Keasling JD (2006) Production of the antimalarial drug precursor artemisinic acid in engineered yeast. Nature 440:940–943
Roessner U, Wagner C, Kopka J, Trethewey RN, Willmitzer L (2000) Simultaneous analysis of metabolites in potato tuber by gas chromatography–mass spectrometry. Plant J 23:131–142
Rose AH, Harrison JS (1987–1995) The yeasts. Vol. 1–6, Academic Press, London, UK
Ross-Macdonald P, Coelho PS, Roemer T, Agarwal S, Kumar A, Jansen R, Cheung KH, Sheehan A, Symoniatis D, Umansky L, Heidtman M, Nelson FK, Iwasaki H, Hager K, Gerstein M, Miller P, Roeder GS, Snyder M (1999) Large-scale analysis of the yeast genome by transposon tagging and gene disruption. Nature 402:413–418
Round AJ, Aguilar MI, Hearn MTW (1994) High-performance liquid chromatography of amino acids, peptides and proteins: CXXXIII. Peak tracking of peptides in reversed-phase high-performance liquid chromatography. J Chromatogr A 661:61–75
Savitzky A, Golay MJE (1964) Smoothing and differentiation of data by simplified least squares procedures. Anal Chem 36:1627–1639
Shao X, Cai W, Pan Z (1999) Wavelet transform and its applications in high performance liquid chromatography (HPLC) analysis. Chemom Intell Lab Syst 45:249–256
Spellman PT, Sherlock G, Zhang MQ, Iyer VR, Anders K, Eisen MB, Brown PO, Botstein D, Futcher B (1998) Comprehensive identification of cell cycle-regulated genes of the yeast Saccharomyces cerevisiae by microarray hybridization. Mol Biol Cell 9:3273–3297
Stein SE (1995) Chemical Substructure Identification by Mass Spectral Library Searching. J Am Soc Mass Spectrom 6(8):644–655
Stein SE (1999) An Integrated Method for Spectrum Extraction and Compound Identification from Gas Chromatography/Mass Spectrometry Data. J Am Soc Mass Spectrom 10:770–781
Styczynski MP, Moxley JF, Tong LV, Walther JL, Jensen KL, Stephanopoulos GN (2007) Systematic identification of conserved metabolites in GC/MS data for metabolomics and biomarker discovery. Anal Chem 79:966–973
Sumner LW, Mendes P, Dixon RA (2003) Plant metabolomics: large-scale phytochemistry in the functional genomics area. Phytochemistry 62:817–836
Tan HW, Brown S (2002) Wavelet analysis applied to removing nonconstant, varying spectroscopic background in multivariate calibration. J Chemom 16:228–240
Tibshirani R, Hastie T, Narasimhan B, Soltys S, Shi G, Koong A, Le Q (2004) Sample Classification from Protein Mass Spectrometry, by “Peak Probability Contrasts”. Bioinformatics 20(17):3034–3044
Tomasi G, van den Bergand F, Andersson C (2004) Correlation optimized warping and dynamic time warping as preprocessing methods for chromatographic data. J Chemom 18:231–241
Torres-Lapasió JR, Baeza-Baeza JJ, García-Alvarez-Coque MC (1997) A Model for the Description, Simulation, and Deconvolution of Skewed Chromatographic Peaks. Anal Chem 69:3822–3831
Uetz P, Giot L, Cagney G, Mansfield TA, Judson RS, Knight JR, Lockshon D, Narayan V, Srinivasan M, Pochart P, Qureshi-Emili A, Li Y, Godwin B, Conover D, Kalbfleisch T, Vijayadamodar G, Yang M, Johnston M, Fields S, Rothberg JM (2000) A comprehensive analysis of protein-protein interactions in Saccharomyces cerevisiae. Nature 403:623–627
van Dam JC, Eman MR, Frank J, Lange HC, van Dedem GWK, Heijnen SJ (2002) Analysis of glycolytic intermediates in Saccharomyces cerevisiae using anion exchange chromatography and electrospray ionization with tandem mass spectrometric detection. Anal Chimica Acta 460:209–218
Van Dien S, Schilling CH (2006) Bringing metabolomics data into the forefront of systems biology. Mol Syst Biol 2:0035 doi:10.1038/msb4100078
Vickers T, Wambles R, Mann C (2001) Curve fitting and linearity: data processing in Raman spectroscopy. Appl Spectrosc 55:389–393
Villas-Bôas SG, Hojer-Pedersen J, Akesson M, Smedsgaard J, Nielsen J (2005a) Global metabolite analysis of yeast: evaluation of sample preparation methods. Yeast 22:1155–1169
Villas-Bôas SG, Moxley JF, Akesson M, Stephanopoulos G, Nielsen J (2005b) High-throughput metabolic state analysis: the missing link in integrated functional genomics of yeasts. Biochem J 388:669–677
Villas-Bôas SG, Mas S, Akesson M, Smedsgaard J, Nielsen J (2005c) Mass spectrometry in metabolome analysis. Mass Spectrom Rev 24:613–646
Vivó-Truyols G, Torres-Lapasió JR, Caballero RD, García-Alvarez-Coque MC (2002) Peak deconvolution in one-dimensional chromatography using a two-way data approach. J Chromatogr A 958:35–49
Vivó-Truyols G, Torres-Lapasió JR, van Nederkassel AM, Heyden YV, Massart DL (2005a) Automatic program for peak detection and deconvolution of multi-overlapped chromatographic signals Part I: Peak detection. J Chromatogr A 1096:133–145
Vivó-Truyols G, Torres-Lapasió JR, van Nederkassel AM, Heyden YV, Massart DL (2005b) Automatic program for peak detection and deconvolution of multi-overlapped chromatographic signals Part II: Peak model and deconvolution algorithms. Journal of Chromatography A 1096:146–155
Walczaka B, Wub W (2005) Fuzzy warping of chromatograms. Chemom Intell Lab Syst 77:173–180
Wang CP, Isenhour TL (1987). Time-warping algorithm applied to chromatographic peak matching gas-chromatography Fourier-transform infrared mass-spectrometry. Anal Chem 59:649–654
Winzeler EA, Shoemaker DD, Astromoff A, Liang H, Anderson K, Andre B, Bangham R, Benito R, Boeke JD, Bussey H, Chu AM, Connelly C, Davis K, Dietrich F, Dow SW, El Bakkoury M, Foury F, Friend SH, Gentalen E, Giaever G, Hegemann JH, Jones T, Laub M, Liao H, Davis RW (1999) Functional characterization of the S. cerevisiae genome by gene deletion and parallel analysis. Science 285:901–906
Wu L, Mashego MR, van Dam JC, Proell AM, Vinke JL, Ras C, van Winden WA, van Gulik WM, Heijnen JJ (2005) Quantitative analysis of the microbial metabolome by isotope dilution mass spectrometry using uniformly 13C-labeled cell extracts as internal standards. Anal Biochem 336:164–171
Wu L, Mashego MR, Proell AM, Vinke JL, Ras C, van Dam J, van Winden WA, van Gulik WM, Heijnen JJ (2006) In vivo kinetics of primary metabolism in Saccharomyces cerevisiae studied through prolonged chemostat cultivation. Metab Eng 8:160–171
Zhu H, Bilgin M, Bangham R, Hall D, Casamayor A, Bertone P, Lan N, Jansen R, Bidlingmaier S, Houfek T, Mitchell T, Miller P, Dean RA, Gerstein M, Snyder M (2001) Global analysis of protein activities using proteome chips. Science 293:2101–2105
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Jewett, M.C., Hansen, M.A.E., Nielsen, J. (2007). Data acquisition, analysis, and mining: Integrative tools for discerning metabolic function in Saccharomyces cerevisiae . In: Nielsen, J., Jewett, M.C. (eds) Metabolomics. Topics in Current Genetics, vol 18. Springer, Berlin, Heidelberg. https://doi.org/10.1007/4735_2007_0222
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