New chromosome-level reference genomes for complex species
Researchers have assembled the first chromosome-level reference genome for the highly endangered Saimaa ringed seal, mapping its genetic structure to aid conservation efforts for the small freshwater population. Concurrently, a separate team has published four new long-read genome assemblies for the cannabis plant, combining them with existing data to construct a comprehensive 66-haplotype pangenome graph that captures structural variations across different cultivars.
Science··Midday
Sequencing the Saimaa ringed seal
Researchers at the University of Eastern Finland and the University of Oulu have mapped the first chromosome-level reference genome for the highly endangered Saimaa ringed seal. Using a skin sample from a living male seal named Tuukka, the team assembled 2.35 billion base pairs across all 17 chromosomes, encompassing approximately 21,800 genes. This high-resolution genomic resource establishes a precise foundation for tracking inbreeding and identifying inherited defects within the isolated freshwater population, which is currently limited to just a few hundred individuals in Finland's Lake Saimaa.[1]
Genetic adaptations to freshwater
Beyond providing a structural map, the complete Saimaa ringed seal genome reveals specific evolutionary shifts tied to the animal's restricted environment. The analysis highlights distinct genetic adaptations in genes responsible for ion transport, kidney function, and olfactory systems, which the researchers attribute directly to the subspecies' long-term survival in a freshwater habitat. These detailed genetic markers offer conservation teams a much sharper tool for monitoring the genetic diversity and long-term viability of the remaining fragmented population.[1]
Mapping cannabis variations
In a parallel effort to map complex genetic variations, a separate study has published four new haplotype-resolved, chromosome-scale genome assemblies for the cannabis plant. Using long-read sequencing data across four specific cultivars, researchers combined these new structures with previously published assemblies to construct a comprehensive 66-haplotype pangenome graph. Spanning 6.48 billion base pairs and nearly 15 million single-nucleotide variants, this reference-free graph captures structural variations across different lineages, though the researchers caution that the older sequencing chemistry utilized limits base-level accuracy in the final output.[2]
