They act as a kind of protective cap for the genome, because with each cell division, the DNA thread of a chromosome shortens a bit. As long as only the telomeres lose their length, this is not a problem for the cell. However, if they are below a critical length, the next cell division would lose important genetic information - time for the cell to protect its neighbors and the body to initiate its suicide program. The length of the telomeres, like a molecular clock, can provide information about the age of a cell.
Appearance of dormouse
The scientists around Thomas Ruf and Claudia Bieber from the University of Veterinary Medicine Vienna are now focusing on this molecular clock. Their subjects were 19 dormice, who lived in an outdoor enclosure near the university. 12 of the animals were not even one year old at the beginning of the study and were still growing. The rest were adults and between three and six years old. display
For their study, the scientists extracted three tissue samples from each dormouse: one in September before the start of the more than eight-month hibernation phase, one in June after hibernation and one in August, ie the most active time of the year in which the animals are intensively up Foraging and also giving birth to their young. The team then compared the telomere length of the different samples and calculated how much the chromosome ends had changed each day during each period.
Why easy if complicated is another option?
The first thing that the scientists noticed in the analysis was: one should not - in a figurative sense - lump all the dormice together. Because in the young animals, the data looked completely different than the older ones. With them, the telomere length decreased drastically during the summer, during the active phase, while it hardly changed in the resting phase in winter. In the case of adult rodents, on the other hand, there was a slight decrease in length in winter, while telomeres even increased in length during the summer. Growth is likely to play an important role in the young, the team explains - it provides significantly more cell divisions and also higher metabolic activity, both of which result in faster shortening of the telomeres. In the older group, however, the influence of telomerase, an enzyme that counteracts the inevitable shortening, seems to predominate.
Despite these complications in the evaluation, the researchers also found a direct relationship between telomere length and hibernation when comparing the individual animals. The more weight the dormouse had lost during the winter, the faster their telomeres shortened. In turn, weight loss is a measure of the rodents' activity: the more they wake up from their deep sleep, the more their metabolism needs to work and the more body fat they consume. One could therefore sum up: The telomere degradation and thus the aging process were slower in the animals, which had the deepest and undisturbed hibernation, more than their more restless conspecifics. The hibernation is thus apparently a special physical condition, which serves in times of bad external conditions to conserve all resources and to keep the body as fit as possible for the next phase of activity.Christopher Turbill (University of Western Sydney) et al .: Journal of the Royla Society: Biology Letters, doi: 10.1098 / rsbl.2012.1095 © science.de - Ilka Lehnen-Beyel