Scientists have found that the African Killi fish has the ability, under unfavorable external conditions, to stop its development for a long time, sometimes exceeding its lifespan. The authors of the discovery believe that studying the mechanisms of this phenomenon will help find a way to stop aging in humans. The results are published in the journal Science.
The African Killi fish, or Nothobranchius furzeri, has the shortest life cycle of all animals. Inhabiting the short-lived lakes of Africa, it has adapted to unstable environmental conditions.
After the rainy season, temporary lakes form in the savannah, which dry up after five to six months. During this time, the Killi fish should grow, reach sexual maturity and lay eggs. And then the fun begins.
Eggs can lie at the bottom of a dry lake for several months or even years, waiting for new rains to start the development of fry. That is, the growth of the embryo is "paused" indefinitely. Such a genetic mechanism has been formed in killy fish over millions of years of evolution under conditions of periodic drought. Scientists believe that the study of this phenomenon, called diapause, could be of great importance in the search for mechanisms to control aging.
American and Canadian researchers led by Professor Anne Brunet from Stanford University studied the biological mechanisms of diapause in the African turquoise killy and found that this phenomenon is associated with the deactivation of genes involved in cell proliferation and organ development, while the activity of genes associated with muscle maintenance and metabolism, on the contrary increases during diapause.
Transcriptomic analysis showed that during diapause, the most activated genes are members of the Polycomb protein complex, in particular, the CBX7 protein. In the nucleus, CBX7 DNA binds to specific histones. According to the researchers, this binding affects the activity of a number of genes, including those involved in muscle function and metabolism, which helps maintain muscle throughout diapause.
"Diapause is a fascinating state of 'suspended life' that can preserve a complex organism for a long time without any visible compromise for later life," Brunet said in a press release.
The authors found that the suspension of development at the embryonic stage does not affect the future life span of the fish, its fertility in adulthood, or growth.
“It can be assumed that the inclusion of a state like diapause, or the use of the molecular mechanism of diapause in some adult tissues or cells may help to maintain them for a long time, - says the scientist. - From a fundamental point of view, it is interesting to understand how the accumulation of damage over time can be stopped or paused. The study of diapause gives us this opportunity."