Most of us who live on the planet have to make Earth through a period of cold weather for at least part of the year, and new research has identified a unique genetic mutation that makes up one-fifth we are more resistant to cold conditions.
This genetic shift inhibits the production of the protein α-actinin-3, which is important for skeletal muscle fiber: The protein is found only in fast-growing (or white) fibers and not in slow-growing fibers (or red).
Based on the results of the new study, people without α-actinin-3 have a higher proportion of slow-twitch needles, and one of the effects is that the body tends to retain energy by building muscle tone through a block- obstruction rather than shaking.
“This suggests that people without α-actinin-3 are better at keeping warm and, energy-wise, at surviving harsher weather, but there was no direct confirmatory evidence for this before, “says physicist Håkan Westerblad, from the Karolinska Institutet in Sweden.
“We can now show that the loss of this protein provides greater stability to cold and we have also found a mechanism for this.”
The researchers recruited 42 men to sit in 14-degree Celsius (57.2-degree Fahrenheit) water while their temperature and muscles were measured. The cold soak lasted 20 minutes at a time with a 10-minute break, for up to two hours in total.
The proportion of participants who were able to maintain their body temperature above 35.5 degrees Celsius (95.9 degrees Fahrenheit) was higher in those with the α-actinin-3 concentration compared to those without – 69 percent of volunteers versus 30 percent.
In other words, genetic mutation seemed to help these participants to conserve energy more efficiently and build more resistance to the cold.
The team also performed follow-up experiments in mice with the same mutation to determine if this mutation had something to do with increasing brown fat stores – a well-known heating substance in mammals – but that did not change. out to be.
People without α-actinin-3 may be better off for cold water swimming or a bout of winter weather, but it may also make them more vulnerable to obesity and type-2 diabetes if they are inactive, the researchers say. It may also increase the risk of falls as they get older, as fast-twitch fibers handle fast muscle movements.
“The change seems to have taken advantage of evolution during the migration to a colder climate, but in today’s society this potential for energy savings could increase the risk. [these] diseases, which we now want to turn our attention to, ”Westerblad said.
As previous research has shown, α-actinin-3 deficiency has increased throughout the population as humans have moved from warmer to colder times, although there are still questions as to whether this mutation present at birth and affecting infant mortality.
It is also interesting to note that athletes who excel in sports involving sprinting and strength (such as sprinting) are more likely to lack this α-actinin-3 deficiency, and for endurance sports the stats are reversed.
As for future research, the team wants to look at how all of this might work at the molecular level, as well as how it might affect muscle disease. For now, it is an important new discovery about this genetic mutation and the associated allele or gene form.
“These decisions provide the mechanism for the increase in [these gene variants’] frequency of how modern humans moved from Africa to the colder climate of central and northern Europe 50,000 years ago, ”the researchers concluded in their published paper.
The research was published in the American Journal of Human Genetics.