Deep-sea rockfish that lives up to 200 years sheds light on genes linked to long lifespan

The genomes of some species of Pacific Ocean rockfishes, that can live up to 200 years, can help find drug targets to slow down age-related damages in the human body, shows new research.

The findings, published in the journal Science on Thursday, shed light on the characteristics of the genomes of such fishes and on the process of ageing in such vertebrates.

The rockfishes, which are among the longest-living vertebrates on Earth, hold clues to genes that determine lifespans and the advantages and disadvantages of living longer, said scientists, including those from the University of California (UC), Berkeley in the US.

Several of the rockfish inhabiting coastal waters around the Pacific Ocean, that were studied, have extreme lifespans spanning decades.

Researchers assessed tissue samples and sequenced the completed genomes of about 88 species of rockfish to get a better understanding of their genes.

The research uncovered some of the genetic differences that highlight widely varying lifespans across the species of the fishes, the scientists noted.

Several vertebrates – including reptiles, birds and mammals – have an astounding diversity of lifespans from a few weeks to over 200 years.

Some of the ageing mechanisms of their bodies, including inflammation and immune system degradation, are linked to human health and disease.

Some of these rockfishes, such as the colourful Calico, live for little more than a decade. Others in the genus Sebastes, like the Rougheye rockfish found from Japan to the Aleutian Islands, can hang out on the seabed in cold, deep coastal waters for more than 200 years, the study pointed out.

“Humans live longer than most vertebrates, but long-lived rockfish can offer humans strategies for improvement,” scientists, including Vera Gorbunova from the University of Rochester in the US, wrote in a separate commentary related to the study.

“Genetic adaptations found in rockfish illustrate that strategies that improve DNA repair and control inflammation may extend life span and health span,” they added.

The wide range of lifespans among the rockfish species and their phenotype traits – differences in size, lifestyle and ecological niche – evolved over a mere 10 million years, a very short span in evolutionary time scale, the scientists said.

In the study, the researchers found a variety of genes associated with longer lifespan, some of which also involve adaptions to living at greater depth and growing larger.

The scientists took care to separate out the genetic variations that allowed the fish to adapt to deeper, colder waters and grow to larger sizes, as these adaptations themselves have the side effect of slowing down metabolism and increasing lifespans.

Some longer-living species had more genes modulating the immune system — particularly a group called Butyrophilins — than shorter-living species.

Since the immune system is involved in regulating inflammation, and increased inflammation is linked to ageing, scientists said the findings may help discover human genes that could be targeted with drugs to slow age-related damages in the body.

Based on the analysis, variations associated with longevity mainly involved three types of rockfish genes.

An enrichment in the number of genes for repairing DNA, variations in many genes that regulate insulin, which has long been known to influence lifespan and an enrichment for genes that modulate the immune system were the three types pointed out by the scientists.

More genes involved in repairing DNA could help protect against cancer and those linked to the immune system could help ward off infections, including cancer, they explained.

While some rockfish species extended their lifespan by simply adapting to deeper, colder waters and increasing their size, the longest-living species boosted their lifespan even further by tweaking their DNA repair, insulin signalling and immune-modulation genes, the scientists pointed out.

“There is an opportunity here to look in nature and see how natural adaptations have shaped lifespan and to think about how those same sorts of genes are acting in our own bodies,” the study’s senior author Peter Sudmant, from UC Berkeley, said in a statement.

The researchers also found some hints of trade offs associated with longer lifespans in some of the rockfish species such as smaller population size.

Drawing a comparison with mammals, the scientists said this was akin to rats, which have short lifespans, vastly outnumbering elephants that live longer.

“In this study, we identified both the genetic causes and consequences of adaptation to extreme lifespan,” Dr Sudmant said.

“It’s very exciting to be able to look at a group of species and see how their phenotype has been shaped through time and the genetic changes that drive that phenotype, and simultaneously, how that phenotype then feeds back and influences the genetic diversity of that population,” he added.

While some of the genes found in the study, that were linked to longevity, had already been discovered, the researchers said the new findings within this one genus of fish provide fresh insights on ageing.

“You could think of rockfish as sort of the perfect storm. in some ways, both on an individual level — having individual fish able to live for a really long time because of size and depth adaptations — but also just having all these different species that are showing these different trends,” Dr Sudmant said.

“They’re a perfect set of individuals to look at, where other people just had a single species to look at.”