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Figure 2 | BMC Bioinformatics

Figure 2

From: Detecting overlapping coding sequences in virus genomes

Figure 2

Six-frame sliding window plot. Example output plot for the 'Six-frame sliding window plots' option (same sequences as in Figure 1). This is a plot of the ∑tree log (LR) statistic calculated in a sliding window along the alignment in each of the six possible read-frames. In each window, the null model is that 'only the known CDS(s) are coding' while the alternate model is that 'both the window and the known CDS(s) are coding'. Panel 1 shows the positions of alignment gaps in each of the input sequences (labelled at right), while panel 2 shows the positions of stop codons in each of the six possible read-frames in each of the input sequences. Panel 3 shows the ∑tree log (LR) statistic in each window in the +0 frame (relative to reference sequence nt 1). The width of each window is indicated by horizontal grey lines (if the reference sequence contains alignment gaps within the window, then the window will appear enlarged in alignment coordinates). The horizontal dashed line is at zero. Panel 4 shows the positions of stop codons in the +0 frame in all the input sequences (same order as in panel 1). Panels 5, 7, 9, 11 and 13 show the same information as panel 3, but for the +1, +2, -0, -1 and -2 frames, respectively. Similarly, panels 6, 8, 10, 12 and 14 show the same information as panel 4, but for the +1, +2, -0, -1 and -2 frames, respectively. Panel 15 shows the known CDSs (here none were entered). Panel 16 shows the summed mean sequence divergence (mutations per nt) at each alignment position (see caption to Figure 1). (See website for more details.) Extended regions of positive signal in panels 3, 5, 7, 9, 11 and 13 indicate potential CDSs (i.e. other than those identified in the null model). In this particular plot, no known CDS(s) were entered, i.e. the null model is that the whole genome is non-coding. Hence the actual Luteovirus CDSs have clear positive signals. Note that several of the reverse read-frames show a false positive signal when they are in the -2 frame relative to a forward read-frame CDS (see website for details).

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