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Output files of Shiba/SnakeShiba

The output directory of Shiba contains the following sub directories:

  • annotation: Assembled GTF file.
  • events: Text files of alternative splicing events.
  • junctions: Junction read counts.
  • results: Results of differential expression and splicing analysis.
  • plots: Plots of alternative splicing events.

The following sub directories are added when SnakeShiba is used:

  • benchmark: Benchmarking results.
  • log: Log files of each step.

Files in results/splicing

  • PSI_[SE,FIVE,THREE,MXE,RI,MSE,AFE,ALE].txt: Results of differential splicing analysis.
  • PSI_matrix_[sample,group].txt: PSI values of each event for all samples or groups. Blank cells indicate that the event did not pass the minimum read count threshold.
  • summary.txt: Numbers of the differentially spliced events for each splicing and event type.

Column description of PSI_*.txt

  • event_id: ID of the event.
  • pos_id: Positional ID of the event. This is useful for comparing the same event across different Shiba runs.
  • strand: Strand of the event (+ or -).
  • gene_id: Gene ID.
  • gene_name: Gene name.
  • label: Label of the event type (annotated or unannotated).
  • ref_PSI: PSI of the reference group.
  • alt_PSI: PSI of the alternative group.
  • dPSI: Delta PSI (alt_PSI - ref_PSI).
  • q: P-value of Fisher's exact test adjusted by the Benjamini-Hochberg method.
  • Diff events: Flag of if the event is differentially spliced between the reference and alternative groups (Yes or No).

PSI_SE.txt

SE
Skipped exon
  • exon: Genomic coordinates of the skipped exon.
  • intron_a: Genomic coordinates of the left-side inclusive intron of the skipped exon.
  • intron_b: Genomic coordinates of the right-side inclusive intron of the skipped exon.
  • intron_c: Genomic coordinates of the exclusive intron of the skipped exon.
  • ref_junction_a: Junction read counts of the left-side inclusive intron of the skipped exon in the reference group.
  • ref_junction_b: Junction read counts of the right-side inclusive intron of the skipped exon in the reference group.
  • ref_junction_c: Junction read counts of the exclusive intron of the skipped exon in the reference group.
  • alt_junction_a: Junction read counts of the left-side inclusive intron of the skipped exon in the alternative group.
  • alt_junction_b: Junction read counts of the right-side inclusive intron of the skipped exon in the alternative group.
  • alt_junction_c: Junction read counts of the exclusive intron of the skipped exon in the alternative group.
  • OR_junction_a: Odds ratio comparing junction read counts of the left-side inclusive intron to those of the exclusive intron, reference group against alternative group.
  • p_junction_a: P-value of Fisher's exact test for the junction read counts of the left-side inclusive intron to those of the exclusive intron, reference group against alternative group.
  • OR_junction_b: Odds ratio comparing junction read counts of the right-side inclusive intron to those of the exclusive intron, reference group against alternative group.
  • p_junction_b: P-value of Fisher's exact test for the junction read counts of the right-side inclusive intron to those of the exclusive intron, reference group against alternative group.
  • p_maximum: Greater of the two P-values of Fisher's exact tests.

PSI_FIVE.txt and PSI_THREE.txt

FIVE_THREE
Alternative 5' and 3' splice sites
  • exon_a: Genomic coordinates of the longer exon using more internal splice site.
  • exon_b: Genomic coordinates of the shorter exon using less internal splice site.
  • intron_a: Genomic coordinates of the intron associated with the longer exon.
  • intron_b: Genomic coordinates of the intron associated with the shorter exon.
  • ref_junction_a: Junction read counts of the intron associated with the longer exon in the reference group.
  • ref_junction_b: Junction read counts of the intron associated with the shorter exon in the reference group.
  • alt_junction_a: Junction read counts of the intron associated with the longer exon in the alternative group.
  • alt_junction_b: Junction read counts of the intron associated with the shorter exon in the alternative group.
  • OR: Odds ratio comparing junction read counts of the intron associated with the longer exon to those of the intron associated with the shorter exon, reference group against alternative group.
  • p: P-value of Fisher's exact test for the junction read counts of the intron associated with the longer exon to those of the intron associated with the shorter exon, reference group against alternative group.

PSI_MXE.txt

MXE
Mutually exclusive exons
  • exon_a: Genomic coordinates of the left-side mutually exclusive exon.
  • exon_b: Genomic coordinates of the right-side mutually exclusive exon.
  • intron_a1: Genomic coordinates of the left-side inclusive intron of the left-side mutually exclusive exon.
  • intron_a2: Genomic coordinates of the right-side inclusive intron of the left-side mutually exclusive exon.
  • intron_b1: Genomic coordinates of the left-side inclusive intron of the right-side mutually exclusive exon.
  • intron_b2: Genomic coordinates of the right-side inclusive intron of the right-side mutually exclusive exon.
  • ref_junction_a1: Junction read counts of the left-side inclusive intron of the left-side mutually exclusive exon in the reference group.
  • ref_junction_a2: Junction read counts of the right-side inclusive intron of the left-side mutually exclusive exon in the reference group.
  • ref_junction_b1: Junction read counts of the left-side inclusive intron of the right-side mutually exclusive exon in the reference group.
  • ref_junction_b2: Junction read counts of the right-side inclusive intron of the right-side mutually exclusive exon in the reference group.
  • alt_junction_a1: Junction read counts of the left-side inclusive intron of the left-side mutually exclusive exon in the alternative group.
  • alt_junction_a2: Junction read counts of the right-side inclusive intron of the left-side mutually exclusive exon in the alternative group.
  • alt_junction_b1: Junction read counts of the left-side inclusive intron of the right-side mutually exclusive exon in the alternative group.
  • alt_junction_b2: Junction read counts of the right-side inclusive intron of the right-side mutually exclusive exon in the alternative group.
  • OR_a1b1: Odds ratio comparing junction read counts of the left-side inclusive intron of the left-side mutually exclusive exon to those of the left-side inclusive intron of the right-side mutually exclusive exon, reference group against alternative group.
  • p_a1b1: P-value of Fisher's exact test for the junction read counts of the left-side inclusive intron of the left-side mutually exclusive exon to those of the left-side inclusive intron of the right-side mutually exclusive exon, reference group against alternative group.
  • OR_a1b2: Odds ratio comparing junction read counts of the left-side inclusive intron of the left-side mutually exclusive exon to those of the right-side inclusive intron of the right-side mutually exclusive exon, reference group against alternative group.
  • p_a1b2: Odds ratio comparing junction read counts of the left-side inclusive intron of the left-side mutually exclusive exon to those of the right-side inclusive intron of the right-side mutually exclusive exon, reference group against alternative group.
  • OR_a2b1: Odds ratio comparing junction read counts of the right-side inclusive intron of the left-side mutually exclusive exon to those of the left-side inclusive intron of the right-side mutually exclusive exon, reference group against alternative group.
  • p_a2b1: Odds ratio comparing junction read counts of the right-side inclusive intron of the left-side mutually exclusive exon to those of the left-side inclusive intron of the right-side mutually exclusive exon, reference group against alternative group.
  • OR_a2b2: Odds ratio comparing junction read counts of the right-side inclusive intron of the left-side mutually exclusive exon to those of the right-side inclusive intron of the right-side mutually exclusive exon, reference group against alternative group.
  • p_a2b2: Odds ratio comparing junction read counts of the right-side inclusive intron of the left-side mutually exclusive exon to those of the right-side inclusive intron of the right-side mutually exclusive exon, reference group against alternative group.
  • p_maximum: Greater of the four P-values of Fisher's exact tests.

PSI_RI.txt

RI
Reteined intron
  • exon_a: Genomic coordinates of the left-side exon.
  • exon_b: Genomic coordinates of the right-side exon.
  • exon_c: Genomic coordinates of the exon containing the retained intron.
  • intron_a: Genomic coordinates of the retained intron.
  • ref_junction_a: Junction read counts of the intron in the reference group.
  • ref_junction_a_start: The left-side exon-intron junction read counts of the retained intron in the reference group.
  • ref_junction_a_end: The right-side exon-intron junction read counts of the retained intron in the reference group.
  • alt_junction_a: : Junction read counts of the intron in the alternative group.
  • alt_junction_a_start: The left-side exon-intron junction read counts of the retained intron in the alternative group.
  • alt_junction_a_end: The right-side exon-intron junction read counts of the retained intron in the alternative group.
  • OR_junction_a_start: Odds ratio comparing the left-side exon-intron junction read counts to the intron junction read counts, reference group against alternative group.
  • p_junction_a_start: P-value of Fisher's exact test for the left-side exon-intron junction read counts to the intron junction read counts, reference group against alternative group.
  • OR_junction_a_end: Odds ratio comparing the right-side exon-intron junction read counts to the intron junction read counts, reference group against alternative group.
  • p_junction_a_end: P-value of Fisher's exact test for the right-side exon-intron junction read counts to the intron junction read counts, reference group against alternative group.
  • p_maximum: Greater of the two P-values of Fisher's exact tests.

PSI_MSE.txt

MSE
Multiple skipped exons
  • mse_n: Number of skipped exons.
  • exon: Genomic coordinates of the skipped exons, separated by semi-colons from the left to the right (e.g., chr1:75790152-75790274;chr1:75790446-75790517).
  • intron: Genomic coordinates of the associated introns of the skipped exons, separated by semi-colons from the left to the right and the last one is the exclusive intron (e.g., chr1:75790057-75790152;chr1:75790274-75790446;chr1:75790517-75791285;chr1:75790057-75791285).
  • ref_junction: Junction read counts of the associated introns of the skipped exons in the reference group, separated by semi-colons from the left to the right and the last one is the exclusive intron (e.g., 25;20;32;489).
  • alt_junction: Junction read counts of the associated introns of the skipped exons in the alternative group, separated by semi-colons from the left to the right and the last one is the exclusive intron (e.g., 386;438;703;598).
  • OR_junction: Odds ratio comparing junction read counts of the associated inclusive introns of the skipped exons to those of the exclusive intron, reference group against alternative group, separated by semi-colons from the left to the right (e.g., 0.07920361952594382;0.05584036006760605;0.055665610718888085).
  • p_juntion: P-value of Fisher's exact test for the junction read counts of the associated inclusive introns of the skipped exons to those of the exclusive intron, reference group against alternative group, separated by semi-colons from the left to the right (e.g., 3.0283773991245187e-54;2.488569122823104e-66;3.7054604961481054e-93).

PSI_AFE.txt and PSI_ALE.txt

AFE_ALE
Alternative first and last exons
  • exon_a: Genomic coordinates of the distal exon.
  • exon_b: Genomic coordinates of the proximal exon.
  • intron_a: Genomic coordinates of the intron associated with the distal exon.
  • intron_b: Genomic coordinates of the intron associated with the proximal exon.
  • ref_junction_a: Junction read counts of the intron associated with the distal exon in the reference group.
  • ref_junction_b: Junction read counts of the intron associated with the proximal exon in the reference group.
  • alt_junction_a: Junction read counts of the intron associated with the distal exon in the alternative group.
  • alt_junction_b: Junction read counts of the intron associated with the proximal exon in the alternative group.
  • OR: Odds ratio comparing junction read counts of the intron associated with the distal exon to those of the intron associated with the proximal exon, reference group against alternative group.
  • p: P-value of Fisher's exact test for the junction read counts of the intron associated with the distal exon to those of the intron associated with the proximal exon, reference group against alternative group.

when ttest is true

  • <sample>_PSI: PSI of the sample. Blank cells indicate that the event did not pass the minimum read count threshold.
  • p_ttest: P-value of Welch's t-test for the PSI of the reference and alternative groups. Please note that the P-value is not adjusted for multiple testing.

Files in results/expression

  • counts.txt: Read counts for all samples.
  • TPM.txt: TPM values for all samples.
  • CPM.txt: CPM values for all samples.
  • DEG.txt: Results of differential expression analysis by DESeq2.

Files in results/pca

  • tpm_pca.tsv: Principal components for TPM matrix.
  • tpm_contribution.tsv: Contribution to each principal component for TPM matrix.
  • psi_pca.tsv: Principal components for PSI matrix.
  • psi_contribution.tsv: Contribution to each principal component for PSI matrix.

An example of output directory structure

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output
├── annotation
│   └── assembled_annotation.gtf
├── events
│   ├── EVENT_AFE.txt
│   ├── EVENT_ALE.txt
│   ├── EVENT_FIVE.txt
│   ├── EVENT_MSE.txt
│   ├── EVENT_MXE.txt
│   ├── EVENT_RI.txt
│   ├── EVENT_SE.txt
│   └── EVENT_THREE.txt
├── junctions
│   ├── junctions.bed
│   └── logs
│       ├── featureCounts.log
│       └── regtools.log
├── plots
│   ├── data
│   │   ├── bar_AFE.html
│   │   ├── bar_ALE.html
│   │   ├── bar_FIVE.html
│   │   ├── bar_MSE.html
│   │   ├── bar_MXE.html
│   │   ├── bar_RI.html
│   │   ├── bar_SE.html
│   │   ├── bar_THREE.html
│   │   ├── pca_PSI.html
│   │   ├── pca_TPM.html
│   │   ├── scatter_AFE.html
│   │   ├── scatter_ALE.html
│   │   ├── scatter_FIVE.html
│   │   ├── scatter_MSE.html
│   │   ├── scatter_MXE.html
│   │   ├── scatter_RI.html
│   │   ├── scatter_SE.html
│   │   ├── scatter_THREE.html
│   │   ├── volcano_AFE.html
│   │   ├── volcano_ALE.html
│   │   ├── volcano_FIVE.html
│   │   ├── volcano_MSE.html
│   │   ├── volcano_MXE.html
│   │   ├── volcano_RI.html
│   │   ├── volcano_SE.html
│   │   └── volcano_THREE.html
│   └── summary.html
└── results
    ├── expression
    │   ├── counts.txt
    │   ├── CPM.txt
    │   ├── DEG.txt
    │   ├── logs
    │   │   ├── DESeq2.log
    │   │   └── featureCounts.log
    │   ├── TPM_CPM.xlsx
    │   └── TPM.txt
    ├── pca
    │   ├── psi_contribution.tsv
    │   ├── psi_pca.tsv
    │   ├── tpm_contribution.tsv
    │   └── tpm_pca.tsv
    └── splicing
        ├── PSI_AFE.txt
        ├── PSI_ALE.txt
        ├── PSI_FIVE.txt
        ├── PSI_matrix_group.txt
        ├── PSI_matrix_sample.txt
        ├── PSI_MSE.txt
        ├── PSI_MXE.txt
        ├── PSI_RI.txt
        ├── PSI_SE.txt
        ├── PSI_THREE.txt
        └── summary.txt