| name | track-generation |
| description | This skill generates normalized BigWig (.bw) tracks (and/or fold-change tracks) from BAM files for ATAC-seq and ChIP-seq visualization. It handles normalization (RPM or fold-change) and Tn5 offset correction automatically. Use this skill when you have filtered and generated the clean BAM file (e.g. `*.filtered.bam`). |
Overview
This skill converts filtered BAM files into normalized signal tracks (BigWig) for genome browser visualization.
It supports both ATAC-seq and ChIP-seq datasets, automatically detecting genome assembly and chromosome size files.
Main steps include:
- Refer to the Inputs & Outputs section to check inputs and build the output architecture. All the output file should located in
${proj_dir}in Step 0. - Always use filtered BAM file (
*.filtered.bam) if available. - Normalize all tracks to 1 million mapped reads (RPM normalization).
- Generate the chrom.size file.
- For ATAC-seq, apply Tn5 offset correction (+4/−5) and generate normalized BigWig (RPM).
- For ChIP-seq, generat RPM-normalized track without applying Tn5 offset correction
Decision Tree
Step 0: Initialize Project
Call:
mcp__project-init-tools__project_init
with:
sample: alltask: track_generation
The tool will:
- Create
${sample}_track_generationdirectory. - Return the full path of the
${sample}_track_generationdirectory, which will be used as${proj_dir}.
Step 1: Generate Chromosome size file
Call:
mcp__bw-tools__generate_chrom_sizeswith:bam_file: Path for the BAM file for generating bigWig Tracksoutput_path: ${proj_dir}/temp/${sample}.chrom.sizes
Step 2: Calculate Scaling Factor
Call:
mcp__bw_tools__calculate_scaling_factorwith:bam_file: Path for the BAM file for generating bigWig Tracks
This step will store result as variable ${scale_factor}
Step 3: Create RPM-normalized BigWig scaled to 1M mapped reads.
- (Option 1) For ATAC-seq data: Apply the standard Tn5 shift (+4/-5bp)
Call:
mcp__bw_tools__bam_to_bigwigwith:bam_file: ${bam_file}chrom_sizes: ${proj_dir}/temp/${sample}.chrom.sizes (from Step 2)output_bw: ${proj_dir}/tracks/${sample_name}.RPM.bwscale_factor: ${scale_factor}shift_tn5: Truetemp_dir: ${proj_dir}/temp(Option 2) For ChIP-seq data: Do Not Apply the standard Tn5 shift by setting
shift_tn5as False