2014-08-17 09:39:35
The function of hibernation is to save resources when food is not abundant.
In these summer days in which television stations try to refresh us with images of beaches in paradises, tax or not, or of places where it is not as hot as in the different country, that is, Spain, I thought that it might as well be I will also refresh you with a scientific topic. And, of course, what better refreshing topic than hibernation, obviously a topic I have never talked about here, not even in winter?
As those who have seen the movie Groundhog Day may know, hibernation is a state of, we could say, prolonged sleep that occurs in some animals, normally in the fall and winter months, and that lasts up to a little while. before the beginning of spring. Studies indicate that hibernation is characterized by a decrease in the speed of metabolism, slow breathing, lower heart rate, and a decrease in body temperature. I told you before that hibernation was refreshing.
The function of hibernation is to save resources when food is not abundant, so wasting energy to obtain it can be very expensive, even deadly. Generally, before hibernating, animals that do so need to store enough energy in the form of fat, which they achieve by gaining weight during the spring and summer, when food is easier to obtain. However, not only animals that live in cold latitudes hibernate; A species of Lemur from Madagascar also does it for no less than seven months a year, even though temperatures in Madagascar are never too cold. In some cases, therefore, hibernation must fulfill objectives for survival that are not yet well known.
Be that as it may, as a physiological process, entry and exit into the hibernation state must be regulated by specific hormones or proteins that, in turn, will be produced by the activity of particular genes. Indeed, studies carried out to date have revealed that three proteins produced exclusively by the liver and that act on the brain are essential. These three proteins are called HP-20, HP-25 and HP-27 (the initials HP stand for Hibernation Protein, and the number indicates the molecular size of each of them). When animals are hibernating, blood levels of these proteins are very low. However, the levels of these proteins are very high in the blood of animals that have left the hibernation state.
An interesting question that had not yet been elucidated was whether the genes that produce these proteins are also found in animals that do not hibernate, although they do not function in the same way in them. If so, it would be necessary to find out if perhaps these proteins regulate other periodic physiological functions, such as the entry into the breeding season in spring, for example.
Researchers at the John Hopkins University School of Medicine, in Baltimore, USA, manage to compare the genomes of several animal species and discover that the genes for the HP-20, HP-25 and HP-27 proteins are also found in the genomes of animals that do not hibernate, such as pigs, cows, elephants, dolphins, rabbits and sheep. However, other animals that also do not hibernate have lost these genes throughout their evolution. These animals include the mouse, the rat, the chicken, the dog and also us humans, who do not hibernate even when the professional soccer league ends.
By San Blas
What do these genes do in animals that do not hibernate and why have they been lost in some species of these types of animals, including ours? To begin to find out, the researchers analyze the levels of HP proteins in the blood of cows throughout the year and verify that they rise and fall in coordination with the seasons, with a maximum of their level occurring in February, back in the day of San Blas (equivalent in Spain to Groundhog Day), just when hibernating animals leave the state of hibernation. In other words, as long as they have the genes that produce them, the control of blood levels of HP proteins is similar in animals that hibernate and those that do not.
To test whether these proteins could still have an effect in animals that have lost the genes that produce them, researchers make them in the laboratory and inject them into mice. The animals treated in this way did not see their body temperature or heart rate affected, but their dietary calorie intake did increase. Consequently, even animals that have lost the genes for these proteins during their evolution continue to possess some of the molecular mechanisms that allow them to respond to their presence.
These studies, published in the Journal of Experimental Medicine, raise refreshing new questions: Why have certain animals that do not hibernate lost the genes that control this process and others have not? Why do animals that have lost them still retain certain genetic and molecular mechanisms that allow them to respond to the proteins produced by them? How do these mechanisms act to modulate body temperature and calorie intake? Could this knowledge be used to manipulate the physiological state of domestic animals, and even our own in conditions such as obesity? Let us hope that science never hibernates before obtaining answers to these and other questions.
NEW WORK BY JORGE LABORDA.
It can be purchased here:
Chained circumstances. Ed. Lulu
Other works by Jorge Laborda
One Moon, one civilization. Why the Moon tells us that we are alone in the Universe
One Moon one civilization why the Moon tells us we are alone in the universe
The intelligence funnel and other essays
#Cienciaes.com #Science #Groundhog