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Study

The axolotl genome and the evolution of key tissue formation regulators

Nowoshilow, Sergej; Schloissnig, Siegfried; Fei, Ji-Feng; Dahl, Andreas; Tanaka, Elly M.

Nature, 2018

Peer-reviewedgenomic studylaboratory

Assembly and annotation of the axolotl genome — at the time the largest animal genome sequenced — using long-read sequencing to resolve an assembly dominated by repetitive sequence, followed by analysis of gene families associated with limb development and regeneration.

Studied in
Ambystoma mexicanum
Sample size
whole-genome assembly

The axolotl genome is about 32 gigabases, roughly ten times the human genome, and its size comes overwhelmingly from expanded repetitive and intronic sequence rather than from extra genes. Several developmental regulators are missing or altered relative to other vertebrates, and a gene expressed specifically in the regenerating limb blastema was identified.

What it means

The authors' reading, and ours. Where they differ, that difference is the point.

How the authors put it

A reference genome makes the genetic basis of limb regeneration tractable, and shows that the capacity does not rest on a large expansion of novel genes.

How NatureHQ reads it

The size is the part that circulates and the composition is the part that matters. Ten times the human genome sounds like ten times the instructions and is nothing of the kind — it is mostly repeated sequence, and the gene count is ordinary. Whatever lets an axolotl rebuild a limb is not a pile of extra genes, which quietly rules out the simplest explanation people reach for.

  • A genome is a parts list rather than a mechanism; it constrains explanations without supplying one.
  • The assembly remains difficult in repetitive regions, and later versions revised it.
  • One laboratory strain, itself derived from a very small founding population.

What this study is used for on NatureHQ

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Published by: Nature PortfolioPublished in a Nature Portfolio journal.

doi.org/10.1038/nature25458

This reference was resolved automatically against Crossref on 2026-08-11.

NatureHQ summarises research in its own words and does not reproduce published text. Reviewed 2026-08-11.