Aquatic, tailed amphibians called newts have large genomes harboring many repeat elements. How these elements shape the genome and relate to newts’ unique regeneration ability remains unknown. In new research, scientists from Karolinska Institute and elsewhere produced a chromosome-scale genomic sequence for the Iberian ribbed newt (Pleurodeles waltl).
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Brown et al. present the chromosome-scale assembly of the 20.3 Gb genome of the Iberian ribbed newt (Pleurodeles waltl), with a unprecedented contiguity and completeness among giant genomes. Image credit: Brown et al., doi: 10.1016/j.xgen.2025.100761.
Also known as gallipato or Spanish ribbed newt, the Iberian ribbed newt is a species of newt endemic to Spain, Portugal and Morocco.
The species is known for its broad flattened head and sharp ribs which can puncture through its sides.
Males measure up to 31 cm (12.2 inches) and females up to 29 cm (11.4 inches). Specimens from northern Africa are smaller than those from European populations.
“The Iberian ribbed newt boasts an impressive regenerative roster, capable of rebuilding lost limbs and regenerating damaged tissues in complex organs, including brain, heart, and eye,” said Karolinska Institute’s Professor András Simon and colleagues.
“Use of this model species would be greatly enhanced by a high-quality genome assembly and annotation.”
“This has, however, been a challenge, primarily due to the large genome size of 20 Gb and considerable enrichment in repeat element sequences.”
The authors found that repeat elements make up 74% of the genomic content in the Iberian ribbed newt.
“This has been a technical challenge, but we succeeded with a detailed mapping which is more comprehensive than in any other species with a similar genome size,” Professor Simon said.
“We determined the exact positions of both protein-coding and non-coding sequences on each chromosome,” said Karolinska Institute Ph.D. student Ketan Mishra.
“We also identified which protein-coding genes are missing in the newt’s genome or have more copies than other species.”
“The results are an important resource for researchers in several fields, such as genome evolution, regenerative and developmental biology, as well as cancer biology.”
“The next step in the research is to focus on functional studies, where we will manipulate molecular processes to determine how these affect the regenerative ability.”
“We also plan to conduct comparative studies with other species to further understand these mechanisms.”
The findings appear in the journal Cell Genomics.
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Thomas Brown et al. Chromosome-scale genome assembly reveals how repeat elements shape non-coding RNA landscapes active during newt limb regeneration. Cell Genomics, published online January 27, 2025; doi: 10.1016/j.xgen.2025.100761
