This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Researchers at the University of Eastern Finland and the University of Oulu have produced the first chromosome-level reference genome for the Saimaa ringed seal. The sequence of every chromosome in the seal's entire genome has now been read and assembled into virtual maps, including its gene content.
The genome provides a unique perspective on the species' genetic makeup and adaptation to its freshwater environment. It also supports evidence-based conservation. The work was presented on the preprint server bioRxiv.
A reference genome is a model—as the name suggests—a point of comparison against which genomic data from other individuals can be analyzed. It is a carefully assembled representation of what the genome of a species typically looks like, how it is organized into chromosomes, the order of its DNA sequences and which genes it contains. "Reference genomes are like maps of a species' genetic information," explains professor Jaakko Pohjoismäki from the University of Eastern Finland.
"A map is only a representation of the terrain, but it still helps us navigate. In the same way, a reference genome helps researchers understand where different genes are located and how individuals differ from one another genetically. Detailed information about genes can also reveal functional differences between species." Unlike most reference genomes, the newly published genome comes from a living Saimaa ringed seal.
The male seal Tuukka was captured in 2023 as part of genetic translocations aimed at safeguarding the remaining genetic diversity of the population. A small skin sample was collected from Tuukka, from which a cell line was established in the laboratory. This provided high-quality DNA with the precision required to determine the sequence of the genome.
The cell line preserves Tuukka's unique genetic makeup in living form, benefiting not only current research and conservation efforts but also future generations of researchers. The Saimaa ringed seal genome is 2.35 billion base pairs long and consists of 17 chromosomes, including the sex chromosomes. It contains approximately 21,800 genes, slightly more than the human genome does.
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