Post Content Researchers claim that the Greenland sharks have equipped themselves with an efficient DNA repair mechanism, which protects them from tumours, and an efficient immune system(Image: Wikimedia Commons)
The world’s longest-living vertebrate, the Greenland shark, lives a slow life; its heart beats just once every 12 seconds. A new research study examines that their heart can beat for centuries without any age-related degeneration.
Their swimming pace is at an average speed of just a foot per second. Astonishingly, every year they grow at a rate of just 0.4 inches a year.Thriving in deep, freezing waters, they reach their sexual maturity at the age of 150 years old. The gigantic sea animal has evolved to live a sluggish life to extend its lifespan to about 200, 400, or more years.
Scientists have discovered that despite biological aging, the sharks have maintained their eyesight and vision, eliminating the possible speculation that they are blind. The slow-moving “sleeper sharks” have functional eyesight adaptable to low light. Studies on their life span may likely give clues about extending human life.
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Insights from the Study at Superior Normal School (SNS)
The study conducted at the Biology Laboratory at the Superior Normal School (SNS) by Alessandro Cellerino and his colleagues in Italy focused on the new investigation of the hearts of the Greenland Sharks. The vital organs of the Greenland sharks were analysed. The heart tissue was compared with that of the belly lantern shark, which is smaller in size and has a shorter life span. The contrast was further developed to enhance the research by analysing the African turquoise killifish, an organism model used by scientists to understand accelerated aging.
Researchers claim that the Greenland sharks have equipped themselves with an efficient DNA repair mechanism, which protects them from tumours, and an efficient immune system, ensuring that the sharks ‘ traits of the sharks defy their age. Despite its slow growth every year, it grows to sixteen feet long. Living in incredibly cold deep waters, its genomes are reportedly full of genes evolved for cancer suppression, anti-inflammatory properties, and a strong DNA repair mechanism.
The study, which included the contrast between the three organisms, revealed that the Greenland Sharks between the ages of 100 and 155 years had a weakened heart. The researchers stated through writing that the heart had severe fibrosis due to scar tissue accumulating, and the stiffness further restricts and impairs the movement of pumping as they age.
The team discovered that cardiomyocytes, the cells responsible for the pumping of the heart, had lipofuscin in massive amounts. Lipofuscin is an age-related pigment whose production occurs when damaged cell machinery does not break down properly. The analysis also revealed that cardiac mitochondria had been damaged, which is responsible for powering the cells and overseeing lysosomes, whose functionality ensures that cellular materials are broken down. Ageing indicators were missing in the comparison with other organisms in the study, the belly lantern shark and the African turquoise killifish.
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Challenging the Myth of Biological Immortality
“All in all, the analysed Greenland shark samples showed clearly recognisable signs of classic ageing at the molecular and tissue level. This proves that ageing processes also take place in the heart tissue of this species,” read the paper published on April 23.
The locomotive ability of the shark to hunt and capture its prey was not affected. This finding was confirmed by selected specimens collected by longline fishing in Greenland.
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The shark’s heart has a remarkable ability to function despite aging due to lower blood pressure compared to other organisms, and the unique structure of the ventral aorta. Furthermore, the elasticity of the heart muscle adds to the surprising mechanism.
“The shark’s resilience to ageing could help scientists better understand longevity in vertebrates, including humans. These findings may also inform translational approaches to mitigate age-related cardiac decline in humans,” the paper read. The study provides substantial evidence for present and future findings about the longest-living vertebrates on Earth.
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(This article is curated by Salonee Kulkarni, who is an Intern with The Indian Express.)
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