| DS Description
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Raw data files of LC-MS apparatus are conv … Raw data files of LC-MS apparatus are converted to a peak table using COWtool (Nielsen et al. 1998) and self-made Perl scripts. The data of ions generated from Trp other than protonated molecule (m/z 205 [M+H]+), e.g. sodium adduct, isotope and fragment ions, were excluded from the peak intensity table before statistical analyses. Blank cells in the table were filled with a value of ‘1000’ as the ion intensity of noise level. Student’s t-test and calculation of the correlation coefficient for data analysis were performed using Microsoft Excel 2000. Independent component analysis (ICA) was performed with a web-based tool, MetaGeneAlyse (http://metagenealyse.mpimpgolm.mpg.de/) (Scholz et al. 2004). All peak intensity data in the peak table were logarithmically transformed for ICA. Hierarchical clustering analysis was performed using TMeV version 4.0 (Saeed et al. 2006). sing TMeV version 4.0 (Saeed et al. 2006).
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