Bulk RNA-seq
Overview
This skill orchestrates a complete, defensible bulk RNA-seq differential-expression study, from raw sequencing reads to enriched pathways and figures. It is a router, not a reimplementation: most stages already have dedicated skills in this repo, and this skill connects them in the right order, fills the one real gap (raw reads → a gene-level counts matrix), and enforces the design and QC decisions that determine whether the final result is trustworthy.
"Defensible" means three things, applied throughout:
- Reproducible — pinned pipeline/tool versions, containers where possible, recorded parameters, fixed random seeds.
- Quality-gated — QC is inspected and acted on before, during, and after quantification, not skipped.
- Statistically sound — adequate replication, a design that matches the biology, counts handled correctly, and FDR-controlled testing.
The pipeline is: FastQC/trim → align/quant (STAR/Salmon) → counts → DE (pydeseq2) → enrichment (pathway-enrichment) → figures.
When to Use This Skill
Use this skill when the user wants to:
- Go from FASTQ files (or a sequencing run) to differentially expressed genes and pathways.
- Run or configure
nf-core/rnaseq, or align/quantify with STAR, Salmon, or featureCounts. - Turn Salmon/STAR/featureCounts output into a counts matrix ready for DESeq2/PyDESeq2.
- Design or sanity-check a bulk RNA-seq experiment (replicates, batch, strandedness) before committing compute.
- Scope an end-to-end RNA-seq analysis and decide which tools and skills to chain.
This is bulk RNA-seq (samples = biological specimens). For single-cell/nuclei data use scanpy; for the DE statistics alone use pydeseq2; for enrichment alone use pathway-enrichment.
The Pipeline at a Glance
flowchart TD
fastq["Raw FASTQ + samplesheet"] --> qc["FastQC + MultiQC"]
qc --> trim["Trim: fastp / Trim Galore"]
trim --> align["Align + quant: STAR and/or Salmon"]
align --> counts["Gene-level counts matrix"]
counts --> de["Differential expression"]
de --> enrich["Pathway / GSEA enrichment"]
de --> fig["Figures"]
enrich --> fig
nfcore["nf-core/rnaseq via nextflow skill"] -.->|"path A"| align
manual["Standalone recipes (this skill)"] -.->|"path B"| align
bridge["build_counts_matrix.py (this skill)"] -.-> counts
pydeseq2skill["pydeseq2 skill"] -.-> de
pwskill["pathway-enrichment skill"] -.-> enrich
vizskill["scientific-visualization skill"] -.-> fig