Black bears hibernate for seven months a year, yet during this time they retain their muscle mass and remain generally healthy.
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They hibernate most of the year, more exactly between five and seven months per year. The black bears are then in a state of controlled hypothermia: they lower their body temperaturedecrease their heart rate, fall into a kind of sleep lethargic and survive without eating or drinking. But even more, “they maintain their functions physical with a atrophy minimal skeletal muscle and metabolic dysfunction,” describes a study recently published in PLOS.
The study authors wondered what was in the blood of these bears that allowed them to keep so well. Because, for humans, such a state of lethargy for such a long duration inexorably leads to a significant loss of muscular mass. The Japanese team then carried out tests on muscle cells human skeletons, by injecting them with serum black bear blood, either collected during the active period or during hibernation. Then they waited and observed the effect on these cells.
An unknown factor in the blood
The result is there: the cells that received bear serum in hibernation have seen their content protein increase dramatically in 24 hours! Conversely, for those who received active bear serum, the natural process of muscle protein breakdown was not stopped. “We indicated that “a certain factor” present in the serum of hibernating bears can regulate the metabolism proteins in cultured human skeletal muscle cells and contribute to the maintenance of mass muscularconcludes physiologist Mitsunori Miyazaki of the University of Hiroshima. However, the identification of this factor has not yet been carried out”.
The researchers assume, however, that everything is at the level of ” I’inhibition of the protein degradation system”that is to say the proteolysis. In the future, they intend to focus on the formal identification of the mechanism at play with the blood serum of black bears. According to them, this would make it possible to develop “new approaches to prevent atrophy and weakness of skeletal muscles in man”.
The grizzly bear, a powerful and very impressive animal Grizzly bear coats can reach a thickness of six centimeters and they shed their winter fur by rubbing against trees. They have an imposing physique with massive legs and shoulders. Their mass varies from 190 to 350 kg for the male and from 125 to 200 kg for the female. Some species can reach weights of 850 kg.© David Bittner, all rights reserved
The kodiak bear is the largest subspecies of brown bear To gain the trust of a bear, here a kodiak bear (Ursus arctos middendorffi) which is the largest subspecies of brown bear (Ursus arctos), you have to show a lot of patience. They behave like humans: they are wary, cautious and reserved. So to have the opportunity to approach one, David Bittner always takes the time to let him get used to him, to talk to him, but above all never to rush things. It is the animal that comes to Man and not the other way around.© David Bittner, all rights reserved
Crunchy but dangerous… Man must respect it Of the eight species of bears that exist on all continents, six are part of the 23% of mammals threatened with extinction. Only the American black bear and the brown bear (the grizzly bear) seem to be spared species for the moment (except in certain communities located in southern Europe and central Asia. In July, August and September, you can observe the bears, they can be “cute”, but you must never forget that they are on their territory and that Man is only their guest. It is important to respect them and to respect them. protected from hunting.They are the jewels of Mother Nature.© David Bittner, all rights reserved
Alaska, an ideal landscape for brown bears The brown bear – like the grizzly bear – and the black bear are species of bear found in North America, especially in Alaska where the country has nature reserves. They prefer semi-open terrain and do well in mountainous areas. The islands of the Kodiak Archipelago, near the south coast of Alaska, have an almost polar climate with cool temperatures, fog, persistent winds and very heavy rainfall throughout the year. It is an ideal habitat for bears.© David Bittner, all rights reserved
The bear and the fox, friends or foes? Bears can reach speeds of 55 to over 66 km/h. During the winter period, they accumulate nearly 200 kg of fat and shelter in crevices or caves to enter a state of lethargy or hibernation depending on the species. Here, in this sublime photo, is it a possible prey? Bears can sometimes be carnivorous…© David Bittner, all rights reserved
Get to know the many bears individually “Over the years and after spending several months with literally hundreds of encounters with sometimes the same bears, some of them feed and sleep beside me. But, to get there, it takes time, a lot of time, and when you see photos showing me close to a bear, you have to know that it is a special bear, one of the few, in which I trust. Believe me. »© David Bittner, all rights reserved
The standing brown bear provides him with better vision Standing, the bears measure between 1.5 and 3 meters. It is estimated that their vision is similar to that of humans but their hearing is finer. Their sense of smell is also extremely more developed. They frequently stand on their hind legs, which allows them to see and smell better, and it gives them a more imposing posture during a confrontation.© David Bittner, all rights reserved
Red salmon, a delight for the kodiak bear Bears are omnivores, they feed on plants, roots, shoots but also fish, insects and small mammals. Grizzlies also hunt large animals like bison, oxen and may prey on black bears. Their favorite dish is still sockeye salmon.© David Bittner, all rights reserved
Dazzling encounter: contact is made The grizzly bear is an omnivorous mammal and scientists estimate their population to be between 30,000 and 45,000 individuals in the wild. It is considered a subspecies of the brown bear and is very common in the United States and Canada. In North America, 70% of their population is sheltered in Alaska. “The summer of 2002 will stay with me forever. I was simply overwhelmed with what I saw this year. Entering a world that few have seen. But above all, experiencing things with bears that very few people, if any, have ever experienced… It’s an indescribable feeling for me to be so close to bears. »© David Bittner, all rights reserved
The mating period in brown bears Grizzlies breed from the age of 4 to 5 years old, but despite everything, females do not have young until they are 9 years old. Each year, at the end of spring, the male mates with different females and gestation lasts about seven months. The female can give birth to up to four cubs which will be nursed until their 18th month. The bear breeds during the months of May and June, sometime after their hibernation period. The male searches for his female by pursuing her with hoarse sounds that can be heard from far away. It can happen that another male enters the game, and the fights can be very dangerous, leaving serious wounds© David Bittner, all rights reserved
In Alaska, lakes and streams are essential for the favorite meal of brown bears The brown bear was once native to Asia and Europe in addition to North America but has become extinct in many areas. Its current total population is estimated at around 200,000 individuals worldwide, including more than 30,000 in the United States and more than 20,000 in Canada. This region of Alaska is essential for the brown bear, which feeds mainly on sockeye salmon, which it can find in abundance, both in the rivers, lakes and streams of the region.© David Bittner, all rights reserved
grizzly bear claws The claws of grizzly bears are long and slightly curved, preventing them from being as good climbers as black bears, for example, however some individuals manage to climb trees to find honey. They also use their claws to fight, to search for food and also to mark their territory on tree trunks. Each of its legs ends in a finger with a long, strong, non-retractable claw, which measures 5 to 7 cm in front and 3 to 5 cm in back.© David Bittner, all rights reserved
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