Rockfish is served on menus around the Pacific Rim, with little thought about fish’s origin or which of the 137 species will be done; it’s often described simply as rockfish or, inaccurately, as rock cod or red snapper. However, this seemingly insignificant fish among the longest-living vertebrates on the planet bears clues about the genes that control longevity as well as the benefits and drawbacks of living longer.
Biologists at the University of California, Berkeley, compare the genomes of nearly two-thirds of the known species of rockfish that inhabit coastal waters around the Pacific Ocean in a study published this week in the journal Science, revealing some of the genetic differences that underpin their widely varying lifespans.
Some rockfish, such as the colorful calico rockfish (Sebastes dallii), survive for less than a decade. In contrast, the rough eye rockfish (Sebastes aleutianus), which may be found from Japan to the Aleutian Islands, can live for more than 200 years on the seabed in cold, deep coastal waters.
Their enormous variety of lifespans, not to mention variances in size, lifestyle, and ecological niche, which scientists term phenotypes, developed during a mere 10 million years, making it one of the most rapid radiations among all fishes.
To investigate the genetic determinants of lifespan in rockfish, the researchers collected tissue samples and occasionally taste samples from 88 different species and sequenced their whole genomes using a cutting-edge method known as Pacbio, or SMRT, sequencing.
They discovered several genes linked to more extended longevity. Some of these genes require adaptations to living at higher depths and becoming more extensive, both of which are linked to a longer lifespan. The findings also emphasize the drawbacks of a long lifetime, such as smaller populations, which are also evident in mammals, with short-lived rats considerably outnumbering long-lived elephants.
According to senior author Peter Sudmant, an associate professor of integrative biology at UC Berkeley, “we found both the genetic origins and effects of adaptation to high lifetime.” Such a collection of species is unique and see how their phenotypic has evolved through time and the genetic changes that drive that phenotype and how that phenotype feeds back and impacts the genetic diversity of that population.
Sudmant admits that many of the biochemical processes connected with longevity discovered by him and his colleagues had previously been identified in genetic analyses of variation within a single animal species, albeit their work does implicate numerous novel genes in these pathways. Nonetheless, the spontaneous variety within this one species of fish spread throughout the Pacific Ocean uniquely captures most of the various genetic elements that determine lifespan.
The finding has ramifications for our knowledge of human longevity as well. Few researchers discovered that longer-lived species have more immune regulating genes, known as butyrophilins, than shorter-lived ones. Because the immune system regulates inflammation and increasing inflammation has been linked to human aging, the findings indicate genes that might be therapeutic targets to prevent age-related damage in the body.
He believes that there is an opportunity here to look at nature, observe how natural adaptations have influenced longevity, and consider how those same kinds of genes function in our bodies.