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The latest findings from aging research
What do African killifishes have to do with human aging? Nothing at all at first glance. Nevertheless, a research team from the Max Planck Institute recognized a genetic principle of aging in fish that apparently also applies to humans. Accordingly, our lifespan is limited by harmful mutations in the genome.
Researchers at the Max Planck Institute for Biology of Aging examined the genetic makeup of 45 different species of the African killifish. The fish is interesting because it has a different life expectancy depending on the location. The Max Planck team searched and found the genetic causes for the fluctuating life expectancy within this species and was able to draw conclusions about human aging based on the principle discovered. The results were recently presented in the "Cell" science journal.
Aquarium residents provide information about aging
In this country, egg-laying tooth carp (killifish) are known as popular inhabitants of aquariums. The fish, originally from Africa, has a genetic peculiarity. There are large fluctuations in the lifespan within his species. The local conditions in which the fish grow up obviously have a major impact on genetics and therefore also on age. But what distinguishes long-lived killifish from their short-lived relatives?
Accumulating mutations accelerate the aging process
Some types of egg-laying tooth carp can only live for a few months, while others can live for several years. The research team at the Max Planck Institute for Biology of Aging analyzed the genetics of 45 different species of killifish to solve the riddle of the different life expectancies. The team discovered a fundamental mechanism of genetics by which harmful mutations accumulate in the genome. According to the study, these accumulations mean that some fish age faster and are more short-lived. The same mechanism has also been demonstrated in humans.
Why are there short-lived species?
One might think that a longer life is generally an advantage for all species, since more offspring can be bred in a longer time. However, some killifish species have shown that certain genes that shorten the life of fish have been passed down through generations. The natural selection did not favor a longer lifespan. Research director Dario Riccardo Valenzano explains why this is so: "African killifishes live in a variety of habitats, from rainforests to dry savannah forests." Depending on how much water is available in the area, they either live long or short.
Experiments of nature
The researchers showed how the availability of water in the region was reflected in the genetics of the fish. "This diversity in life is like an experiment by nature on different survival strategies," reports Valenzano. This makes the killifish a unique system for studying the evolution of aging.
Bloated genome leads to short life
"The fish do not seem to be short-lived because this is good for them or because they adapt to their environment, but because they live and breed longer in longer rainy seasons," summarizes the study director. They recognized this principle on the basis of genetic analyzes. The researchers found that short-lived species have a bloated genome that is full of repeating DNA sequences. As a result, harmful mutations accumulated in the fish, which had a negative effect on DNA repair, metabolic control and energy production. Genes that control the aging process were also affected by the mutations.
Some genes are particularly important for old age
Accordingly, certain genes only appear to play a stronger role in old age. Since the fish in water-poor regions did not reach their full age anyway due to the local conditions, the natural selection for genes that are important in old age simply did not seem to work as efficiently. "It doesn't matter whether a mutation makes the fish sick in old age, because they have already multiplied and transferred this mutation to their offspring," said the head of research. This explains the bloated genome and the accumulation of harmful mutations in short-lived killifish.
What does that mean for humans?
Further investigations showed that this principle also occurs in humans. As the team documented, harmful mutations also accumulate in humans, especially in the genes associated with aging. "We found that the frequency of harmful mutations in a gene goes hand in hand with when the gene is read," emphasizes Valenzano. Human genes that only play a role in old age are therefore more likely to cause more harmful gene variants. In doing so, the researchers also discovered new connections between genes and aging, which were previously not known to be connected with the aging process at all. (vb)
Also read: The aging process slowed down! This therapy clearly slowed down aging.
Author and source information
This text corresponds to the requirements of the medical literature, medical guidelines and current studies and has been checked by medical doctors.
Graduate editor (FH) Volker Blasek
- Max Planck Institute for Biology of Aging: Neutral evolution shapes life expectancy and aging (accessed: 04.07.2019), age.mpg.de
- Dario Riccardo Valenzano / Rongfeng Cui / Tania Medeiros / u.a .: Relaxed Selection Limits Lifespan by Increasing Mutation Load, Cell, 2019, cell.com