The giant axolotl genome uncovers the evolution, scaling, and transcriptional control of complex gene loci

The axolotl, a salamander, has an enormous genome, ten times larger than a human's. This research assembled the axolotl genome to study how chromosomes are organized and how genes are regulated across such a vast expanse of DNA. The researchers used a method called Hi-C to map how different parts of the axolotl genome contact each other. This helped them piece together the fragmented genome sequences into chromosome-scale structures. The study found that even though the axolotl genome is huge, the way genes are organized and regulated is similar to other animals, like humans, but scaled up. This suggests that basic genetic mechanisms are conserved even with large genome size differences.

• 1
  The chromosome-scale assembly of the 32 Gb axolotl genome was achieved using Hi-C contact data.
• 2
  Analysis of the Major Histocompatibility Complex (MHC) region revealed conserved syntenic arrangements with other vertebrates and lineage-specific amplifications of certain gene families.
• 3
  Topologically Associating Domains (TADs) and long-distance regulatory elements, such as those controlling Fgf8, are expanded in the axolotl genome, scaling 20- to 50-fold compared to humans, while maintaining similar organizational dynamics.