bio-chipseq-spike-in-normalization

bio-chipseq-spike-in-normalization is a skill for Claude Code, Codex from GPTomics/bioSkills. It costs 175 tokens per session (4,672 once invoked), scanned A, original, MIT.

A guide to normalising ChIP-seq and CUT&RUN or CUT&Tag data with spike-in material: extra reference DNA added to each experiment. This makes signal changes between conditions more quantitatively comparable.

In plain words
What is it for?
Use it to calculate scaling factors from Drosophila or E. coli reference reads and apply them in tools such as DiffBind, DESeq2, edgeR, or deepTools.
Why use it?
Standard normalisation can hide global increases or decreases in DNA-binding signal; spike-in reads provide an external reference for scaling the results.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: positional $N argument.

Good fit Use it to calculate scaling factors from Drosophila or E. coli reference reads and apply them in tools such as DiffBind, DESeq2, edgeR, or deepTools.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/gptomics/bioskills/spike-in-normalization
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add GPTomics/bioSkills --skill spike-in-normalization
Clone the repo
git clone --depth 1 https://github.com/GPTomics/bioSkills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for bio-chipseq-spike-in-normalization

README.md
[![agentmods](https://agentmods.dev/badge/skills/gptomics/bioskills/spike-in-normalization/github.svg)](https://agentmods.dev/skills/gptomics/bioskills/spike-in-normalization)
Your own site
<a href="https://agentmods.dev/skills/gptomics/bioskills/spike-in-normalization"><img src="https://agentmods.dev/badge/skills/gptomics/bioskills/spike-in-normalization/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for bio-chipseq-spike-in-normalization

Your own site · 80×15
<a href="https://agentmods.dev/skills/gptomics/bioskills/spike-in-normalization"><img src="https://agentmods.dev/badge/skills/gptomics/bioskills/spike-in-normalization.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 175 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,672 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00175 $0.04672
Opus 5 $0.00088 $0.02336
Sonnet 5 $0.00035 $0.00934
Haiku 4.5 $0.00017 $0.00467

Measured 6d ago against content hash 59a3f4da425f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

bio-chipseq-spike-in-normalization scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

chip-seq/spike-in-normalization/SKILL.md · 349 lines

How it starts

The opening of the file, as written. The whole thing — 349 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Version Compatibility

Reference examples tested with: DiffBind 3.20+, DESeq2 1.42+, edgeR 4.0+, csaw 1.36+, ChIPseqSpikeInFree 1.6+, SpikChIP 1.0+, SpikeFlow (NAR Genom Bioinform 2024), samtools 1.19+, bowtie2 2.5+.

ChIP-seq Spike-In Normalization

"Account for global signal changes that defeat standard normalization" -> Add exogenous reference chromatin (Drosophila for human/mouse ChIP-Rx; E. coli carryover for CUT&RUN/CUT&Tag) at fixed concentration BEFORE IP, derive scaling factors from spike-in read counts, and apply at the read or size-factor level (never to peak counts) to enable quantitative cross-condition comparison.

  • CLI: align reads to combined target + spike genome; count spike reads via samtools view -c
  • R (DiffBind integration): dba.normalize(obj, spikein = TRUE)
  • R (DESeq2 / edgeR): sizeFactors(dds) <- 1 / scale_factors (note inverse)
  • CLI (deepTools tracks): bamCoverage --scaleFactor <derived> (use alone; --normalizeUsing compounds with it)
  • Wrapper: SpikeFlow (Snakemake; 2024) automates end-to-end
  • Post-hoc detection: ChIPseqSpikeInFree (when no spike-in was added)

The fundamental rule: spike-in scaling is applied at the READ level (via size factors or --scaleFactor), never multiplied into peak counts. This is a common implementation error in published spike-in ChIP.

When Spike-In Is Required

Experimental design Spike-in needed?
HDAC inhibitor -> global H3K27ac increase Yes
BET inhibitor (JQ1, OTX015) -> global BRD4 / H3K27ac decrease Yes
EZH2 inhibitor -> global H3K27me3 loss Yes
DNMT inhibitor -> global 5mC loss; downstream histone mark shifts Yes
Target factor knockdown / degron Yes (or matched-input subtraction)
Cell-cycle synchronization / arrest Yes
Dosage titration Yes
Standard TF perturbation, local rebinding expected No (reads-in-peaks RLE works)
Histone mark cross-cell-type comparison Recommended
CUT&RUN/CUT&Tag standard E. coli carryover (automatic); deliberate Drosophila for high-stakes
Replicate-only experiment, no condition comparison No

Read the full file on GitHub · 349 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 6d ago First seen · 349 lines · 175 tokens per session scan A 59a3f4da425f

Subscribe to this mod's changes

bio-chipseq-spike-in-normalization is a skill published in the GitHub repository GPTomics/bioSkills (1,199 stars, last pushed 25d ago), licensed MIT. It adds 175 tokens to every session and 4,672 once invoked, about $0.0009 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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