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Fig. 2 | Malaria Journal

Fig. 2

From: Metabolic alterations in the erythrocyte during blood-stage development of the malaria parasite

Fig. 2

Global metabolomics of uninfected (uRBC) and parasite-infected erythrocyte (iRBC) cultures. a Heatmap of metabolite abundances in uRBC and iRBC at 0, 8, 16, 24, 32, and 40 h. Each of the 501 rows represents a distinct metabolite. There are four replicates for each time point. Orange indicates an abundance level of a metabolite greater than the median value, which is computed across uRBCs and iRBCs, whereas blue indicates an abundance level lower than the median. b Principal component analysis of metabolomic data from uRBCs (black) and iRBCs (red). The uRBC and iRBC data separated along the first (PC1), second (PC2), and third (PC3) principal components, with the maximum separation occurring between the ellipses labelled ‘16–40 h’ and ‘16–32 h,’ respectively. The uRBC data formed two clusters: 0–8 h and 16–40 h. Ellipses are drawn only to visually highlight uRBC and iRBC data that were clustered together; they do not reflect the confidence intervals of the clusters. The ellipses labelled ‘16–32 h’ and ‘16–40 h’ contain 12 and 16 data points, respectively, although they are not discernible because of overlap among some of the data points. The percentage of the total data variance explained by each principal component is shown in parentheses along each axis. c Average variance (σ2) of metabolite abundance at a given time point within replicates. First, the variance within replicates is computed for the abundance of a given metabolite and then the average across all metabolites is computed for each time point. The average variance is shown in black for uRBCs and in red for iRBCs. The dotted horizontal line shows the mean of the average variance, which is ~ 4%. d The average fold change (\( \overline{\text{FC}} \)) in metabolite abundance between different time points. The fold change in the kth metabolite at time point ‘j’ against time point ‘i’ is computed as \( {\text{m}}_{\text{k}}^{\text{j}} / {\text{m}}_{\text{k}}^{\text{i}} \), where i and j are each set to 0, 8, 16, 24, 32, or 40 h. Hence, each element ij indicates the average metabolite fold change computed using the dataset at time points i and j, where N denotes the total number of metabolites. Compared to the average metabolite fold changes in uRBCs, those in iRBCs are more pronounced at all sampled time points. The results are shown on a log2 scale. e Hierarchical clustering analysis (HCA) of the metabolomic data in a after averaging the metabolite abundances among the replicates. The colour scheme and scale are as shown in a. Metabolites were clustered based on the Euclidean distance similarity of their temporal profiles. HCA identified five distinct clusters, which are shown in distinct colours with a corresponding number. Generally, within each cluster, metabolites that were downregulated in uRBCs were upregulated in iRBCs and vice versa

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