Have you ever, thinking about ageing, just wanted to stop time? Have you ever wanted to press one huge pause? You must have watched series and movies about vampires that do not age but remain beautiful and youthful for a long time. If you thought such a thing could not be achieved, you were wrong. The best evidence for this is the species Nothobranchius furzeri.
Nothobranchius furzeri inhabits ponds in Mozambique and Zimbabwe, which disappear during the dry season for several months, and the fish remain without their habitat until the rain returns. However, the species has adapted extremely well to such an extreme environment. It accomplishes this in a way that its life cycle consists of two very different phases: the fast-growing phase and the diapause.
After hatching, the individuals grow rapidly, reach sexual maturity in less than a month, and age rapidly. This fast-growing phase occurs during the rainy season and is very important so that individuals can reproduce rapidly while water is still present. This is extremely important for the survival of the species in question. Since such adults live from 4 to 6 months, the vast majority of them die during the rainy season, so the upcoming drying of the pond does not pose a great threat to them.
Embryos stop their development during the dry months. They are uniquely adapted to survive in dry mud during the dry season. We say that they are in a state of diapause, in which they can be from 5 months to 2 years. In the state of diapause, all developmental processes are stopped and the embryos are protected from prolonged drought. They remain in this state until the next rainy season when the ponds are refilled with water.
Diapause is a specialized condition characterized by temporary cessation of development and high tolerance to various living conditions and is essential for the protection of offspring from adverse environments.
A team of scientists analysed embryos in diapause to determine which genes are active [ 2]. Although young embryos developed muscles and the heart and brain before entering diapause, genes involved in organ development and cell proliferation were excluded after entering it. Some other genes were active. The researchers found that an activated CBX7 gene suppressed genes involved in metabolism, but activated those important for muscle maintenance and for staying in diapause. Embryos without the CBX7 gene had previously come out of diapause, and their muscles began to decline after a month. These studies showed that embryos not only passively waited for better living conditions but also maintained their own underdevelopment through various processes. This two-phase life cycle is also present in laboratory conditions with constantly present water, indicating that entry into diapause is controlled by genes.
However, not all embryos enter diapause. Some naturally skip the state of diapause and continue to develop if they are provided with the living conditions to do so (e.g., growing in a laboratory setting).
This research could help scientists discover how to treat age-related diseases and learn how to preserve human organs in the long run.
2.How African turquoise killifish press the pause button on aging, 2020, https://www.sciencenews.org, accessed 24.12.2020