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Post by Deleted on Mar 28, 2018 15:31:58 GMT -5
Pretty much what the title is asking. Does anyone have any data regarding the brown bear's immune system? I ask this because I read in some old threads (yuku) that hunters rarely poisoned these animals, and often preferred traps or just shooting them.
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Post by Polar on Mar 28, 2018 19:26:44 GMT -5
Bears have a higher amount of both red blood cells and white blood cells than most other carnivores, which increases endurance and immunity. Also greater hemoglobin per unit of blood plasma which increases oxygen transfer speed to the lungs. Greater oxygen transfer speed can also indicate faster cellular regeneration and more immediate immune response.
Very interesting topic contrary to the "versus" topics that are popping up. We should discuss more of bear morphology, both general and molecular.
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Post by Polar on Mar 28, 2018 19:45:43 GMT -5
Body Temperature during Hibernation Is Highly Correlated with a Decrease in Circulating Innate Immune Cells in the Brown Bear (Ursus arctos): A Common Feature among Hibernators?"The state of lowered metabolism during hibernation in mammals is a showcase of cell preservation strategies for muscle, bone, and the circulatory and innate immune systems. Hibernating mammals tolerate extremes in organ perfusion, oxygen saturation, temperature, immobilization, and calorie intake - which in combination would be lethal to humans. Hibernators may therefore act as reverse translational models for human health and disease.
In most hibernating mammals, torpor phases are interrupted by euthermic arousal phases (reviewed in: (1)). During torpor, metabolism is severely depressed but hibernation also involves the inhibition of thermogenesis, leading to a considerable decrease in body temperature (Tb). The induction of torpor begins with lowering of the metabolic rate, followed by hypothermia as the Tb drifts downward (reviewed in: (1-3)). Various degrees of cold torpor have been observed over a phylogenetically wide range of mammals and is most drastic in bats and rodents. The champion of all torpid mammals is the hibernating arctic ground squirrel (Urocitellus parryii, previously called Spermophilus parryii), which exhibits body temperatures as low as -2.9°C (4).
In a recent paper by Bouma et al. (5), the current knowledge of the immune system of hibernating mammals was reviewed. Although there are few data from this field, one of the most striking phenomena is the reduced number of circulating leukocytes found in all hibernating mammals studies so far. The studies reviewed by Bouma et al. (5), finding leukopenia in hibernating mammals, were all conducted on small species, including the European hamster (Cricetus cricetus), European hedgehog (Erinaceus europeaus), European ground squirrel (Spermophilus citellus), arctic ground squirrel (Urocitellus parryii), and the thirteen-lined ground squirrel (Ictidomys tridecemlineatus, previously called Spermophilus tridecemlineatus); all species in which Tb drops drastically during hibernation. The authors (5) raised the question of whether the reduced number of circulating leukocytes in mammalian hibernators is due to torpor per se or secondarily to the low Tb. Most recently, the same authors showed that, at least in small species (Syrian and Djungarian hamsters), Tb during hibernation indeed controls leukopenia (6).
The brown bear (Ursus arctos) is an exception among hibernators. The definition of hibernation as a temporary physiological state, characterized by a controlled lowering of the metabolic rate, as well as a dramatic drop in Tb (1), does not strictly apply to the brown bear. Instead, the bear has been classified as a hibernator based on the length of the torpid period (5-7 months in Scandinavia) (7-9). However, in a recent study on black bears (Ursus americanus), it was shown that bears are true hibernators; involving processes of both metabolic and thermal regulation (10). Whereas the bear's body temperature remains relatively stable during hibernation with a less dramatic drop in comparison to other hibernators (from 37°C in summer to 33-30°C in winter) (10, 11), the absolute metabolic rate in the bear is substantially reduced by 75%, and it takes several weeks after emergence for metabolic rate to return to normal levels (10). The slight Tb lowering in hibernating black bears is uncoupled from metabolic suppression (10), and, most recently, it was demonstrated that the expression of a number of genes involved in regulating the metabolism is adjusted during winter hibernation (12). By this, the bear offers a unique opportunity to further elucidate whether immune depression during hibernation is primarily caused by a lowered Tb or might be intrinsic to torpor per se.
In the present study, we examined immune cell counts in peripheral blood of 13 free-ranging Scandinavian brown bears during hibernation and again during the active period in summer. The results were compared to data from the literature available on different species on immune function during hibernation."Bears immune systems appear to get weaker during hibernation. Makes sense because: 1) Less energy expenditure, thus less need for food access during hibernation. 2) Not much exposure to outside elements during hibernation.
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Post by brobear on Mar 28, 2018 20:51:46 GMT -5
Farmers, ranchers, and shepherds killed millions of predators in the American West including bears with Strychnine poisoning. Also with steel traps and of course guns and dogs.
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Post by Deleted on Apr 6, 2018 12:10:16 GMT -5
Farmers, ranchers, and shepherds killed millions of predators in the American West including bears with Strychnine poisoning. Also with steel traps and of course guns and dogs. I have read that killing bears through use of poisons wasn't very effective and wasn't commonly used much compared to simply shooting them. |
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Post by Polar on Apr 6, 2018 12:41:06 GMT -5
The following is an interesting article about the immune systems of polar bears and how their immune systems will adapt to the bacteria and bio-mass types commonly found across the Arctic shore into North America, in case the ice floes completely melt:
Polar bears and the threat of disease" Genetic studies show that polar bears have “A relatively naïve immune system,” according to research wildlife biologist Todd Atwood, who heads the U.S. Geological Survey – Alaska Science Center Polar Bear Research Program. When polar bears are forced ashore they face new threats from disease.
Polar bears, marine predators known for traversing arctic sea ice to hunt seals, rarely interact with terrestrial species such as caribou. Atwood outlined “From a disease perspective, the sea ice acts as a structural barrier to the vectoring of certain disease agents.” Polar bears’ naïve immune systems haven’t encountered a wide variety of diseases. “They can be particularly vulnerable to novel infectious agents because they don’t have that genetic diversity for their immune system to recognize these different infectious agents and mount an immune response.”
Changing habitat = new risks
Polar bears face new disease threats. The polar bears’ world is changing. In 2008 polar bears were listed as threatened under the Endangered Species Act, which afforded the bears new protections. It is worth noting that, according to the National Wildlife Federation, polar bears were the first vertebrate species to be listed by the U.S. Endangered Species Act as threatened by extinction primarily due to global warming.
Polar bears travel arctic pack ice to hunt seals, their primary prey; ongoing depletion of sea ice extent and thickness causes complications for the species. “A consequence of climate change is that we are losing that sea ice habitat that served as a structural barrier and bears are responding in ways that are probably exposing them to new risk factors,” Atwood said.
Atwood called sea ice conditions volatile and highly dynamic. “The big concern is that that period of time when quality sea ice habitat is unavailable to polar bears is getting longer and longer.” When there’s no ice along Alaska’s north shore, individuals from the southern Beaufort Sea polar bear population have two choices: either swim to the distant pack ice or remain and scavenge along the coast. Unusual amounts of time spent scavenging brings polar bears into contact with species and disease threats their immune system isn’t necessarily equipped for. Atwood stated “We’re concerned that we’re seeing this climate-mediated increase of onshore occurrence and that then is exposing bears to novel risk factors that they haven’t been historically exposed to.”
Alaska called a crossroads
When polar bears feed alongside birds at sites where the remains of subsistence-harvested bowhead whales are aggregated on Alaska’s northern coast, they may be encountering risks from distant regions of the world. Alaska serves as a destination for millions of migratory birds that travel to the state from all around the world. Traveling animals as well as increasing amounts of human tourism and shipping opportunities can carry pathogens and toxins to the Arctic environment. “A number of ecological epidemiologists have made the prediction that we will see range expansion of parasites and infectious agents northward. And we’re seeing some of the early examples of that with the increased toxoplasma [parasite] exposure,” in polar bears, Atwood reported.
Coxiella
In the last 4 or 5 years scientists have noted polar bear exposure to infectious agents already to known to be present in the Arctic: brucella, phocine distemper and canine distemper. What’s more, “We’ve also seen exposure to infectious agents previously undocumented in polar bears.” One of those is Coxiella burnetii, a bacterial pathogen that causes disease in animals and humans.
The World Health Organization reports: “Infectious diseases are caused by pathogenic microorganisms, such as bacteria, viruses, parasites or fungi; the diseases can be spread, directly or indirectly, from one person to another. Zoonotic diseases are infectious diseases of animals that can cause disease when transmitted to humans.”
Atwood: “Coxiella is a bacterium that is the causative agent of the disease called Q fever― a zoonotic disease that can move back and forth between humans and wildlife,” Atwood illuminated. Coxiella is highly pathogenic, which means it’s capable of causing disease and spreads easily. “It was weaponized by the U.S. bioweapons program in the 1950’s because of its high pathogenicity.” Atwood said “It causes like your typical flu-like disease in people. And we don’t know what type of disease it causes in wildlife but we do know that it can interfere with reproduction.”
Reproductive interference is one more pressure on a species already listed as threatened.
Blood record
Polar bear exposure to Coxiella burnetii was documented in 2013 in the southern Beaufort Sea population. Atwood described: the previous northernmost known case was in northern fur seals in the Pribolof islands, “So it’s made a pretty big jump in range from that animal into our neck of the Arctic. We don’t know what the population level consequences of that are, we don’t know how they are being exposed.” To help answer those questions the researchers accessed the USGS archive of polar bear blood samples taken during routine captures since the mid-eighties. “We started looking back in time to see where we can locate the first instance of exposure and we’re far from having that done. But we have found a case as early as 2007.” Atwood’s team looks to understand “Is increased exposure a result of the changing behaviors bears exhibit because of loss of sea ice habitat? And also does it have population level implications?”
Monitoring
In order to keep tabs on polar bear health and on the status of disease in the Arctic, Atwood noted “We need to start really ramping up our monitoring capabilities now. If we are not monitoring, we’re not going to be able to detect an increase trend or prevalence or, more importantly, detect things that are occurring that historically have not been here.”
The status of polar bear health has implications for human populations as well. Polar bears are apex predators situated at the top of the food chain; accordingly, they are impacted by the health and status of the organisms below them in the food chain. Humans in the Arctic, especially those following a subsistence lifestyle, are similarly apex predators. Polar bears are called sentinels of ecosystem health– their status gives us insight into the status and well-being of other species, including humans." |
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Post by brobear on Apr 20, 2018 10:00:24 GMT -5
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Post by brobear on Sept 8, 2018 8:14:29 GMT -5
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Post by brobear on Mar 8, 2019 6:45:38 GMT -5
epiphany - A grizzly will never turn his back on carrion. No matter the flies crawling on the carcass or how many maggots are crawling through it, to a grizzly this is prime-rib. Therefore, he pretty-much needs a strong immune system. Any thoughts on this?
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Post by King Kodiak on Mar 8, 2019 7:07:59 GMT -5
epiphany - A grizzly will never turn his back on carrion. No matter the flies crawling on the carcass or how many maggots are crawling through it, to a grizzly this is prime-rib. Therefore, he pretty-much needs a strong immune system. Any thoughts on this?
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Post by King Kodiak on Mar 8, 2019 7:10:08 GMT -5
Study: Panda immune system more resilient than previously understood New research shows giant pandas have a stronger immune system than previously known, because the panda immune system develops different antigens depending on where it lives. This genetic diversity is a natural defense against extinction, because it means a single pathogen cannot wipe out the entire population. The study shows pandas are more genetically diverse than Bengal tigers, Namibian cheetahs and other endangered species. Pandas have been listed on the International Union for the Conservation of Nature's endangered species lists since 1990, but the new findings show that they might be more resilient to environmental change than researchers believed. The study focused on the pandas' major histocompatibility complex (MHC). They chose this section of the genome because it is the only one that adapts to environment. Other parts of the genome remain standard across a species and are therefore not indicative of genetic diversity. www.cbsnews.com/news/study-panda-immune-system-more-resilient-than-previously-understood/ |
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Post by Deleted on Mar 11, 2019 8:13:43 GMT -5
Brown bears indeed have very powerful saliva. |
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Post by brobear on Nov 7, 2019 8:54:58 GMT -5
www.sciencedaily.com/releases/2017/10/171030084745.htm Bears not bothered by diet high in saturated fats Grizzlies show no clinical signs of disease following short-term consumption of saturated fats but scientists question long-term health. Campgrounds and cottages are getaways for humans. They are also locations where grizzly bears are acquiring appetites for human foods that are high in saturated fats. Diets high in saturated fats are associated with many diseases in humans. Does the health of a bear suffer too? A new study published today in the Canadian Journal of Zoology found that captive bears fed a diet high in saturated fats and low in "healthy" polyunsaturated fats did not show symptoms of disease typically observed in humans eating foods high in saturated fats such as insulin resistance, a precursor to type 2 diabetes. The article, "Systemic effects of a high saturated fat diet in grizzly bears (Ursus arctos horribilis)" by Danielle Rivet, Lynne Nelson, Chantal Vella, Heiko Jansen, and Charles Robbins was published today in the Canadian Journal of Zoology.
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Post by brobear on Apr 26, 2020 7:20:09 GMT -5
en.wikipedia.org/wiki/Bear Mortality Hunters with shot bear, Sweden, early 20th century. This photograph is in the Nordic Museum. Bears do not have many predators. The most important are humans, and as they started cultivating crops, they increasingly came in conflict with the bears that raided them. Since the invention of firearms, people have been able to kill bears with greater ease. Felids like the tiger may also prey on bears, particularly cubs, which may also be threatened by canids. Bears are parasitized by eighty species of parasites, including single-celled protozoans and gastro-intestinal worms, and nematodes and flukes in their heart, liver, lungs and bloodstream. Externally they have ticks, fleas and lice. A study of American black bears found seventeen species of endoparasite including the protozoan Sarcocystis, the parasitic worm Diphyllobothrium mansonoides, and the nematodes Dirofilaria immitis, Capillaria aerophila, Physaloptera sp., Strongyloides sp. and others. Of these, D. mansonoides and adult C. aerophila were causing pathological symptoms. By contrast, polar bears have few parasites; many parasitic species need a secondary, usually terrestrial, host, and the polar bear's life style is such that few alternative hosts exist in their environment. The protozoan Toxoplasma gondii has been found in polar bears, and the nematode Trichinella nativa can cause a serious infection and decline in older polar bears. Bears in North America are sometimes infected by a Morbillivirus similar to the canine distemper virus. They are susceptible to infectious canine hepatitis (CAV-1), with free-living black bears dying rapidly of encephalitis and hepatitis.
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Post by brobear on Jul 5, 2021 11:21:13 GMT -5
See, "Dietary biology of the brown bear" in the brown bear section. Brown bears, among their huge assortment of food choices, consumes carrion whenever found. The microbes which all carrion is infested with would kill a human. It takes a strong immune system to feed regularly on carrion. Consider also that a bear, especially a brown bear, finds himself in fights often either with other bears or other wild beasts. They seem to heal efficiently even from horrible wounds.
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Post by OldGreenGrolar on Jul 5, 2021 17:20:46 GMT -5
Brown bear’s have medicine of their own. O doubt one often gets sick. |
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Post by brobear on Jul 5, 2021 17:31:39 GMT -5
Brown bear’s have medicine of their own. O doubt one often gets sick. Pictured is a very good book, an easy read filled with interesting bear facts. The author tells of how the Mama Bear teaches her cubs what they should and should not eat. She teaches them about natural medicines for specific illnesses. I highly recommend this book to all bear enthusiasts.  |
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Post by brobear on Jul 9, 2021 3:30:59 GMT -5
The only living things that I hate are the parasites. "Parasitism is a kind of symbiosis, a close and persistent long-term biological interaction between a parasite and its host."
It's difficult for me to even imagine how difficult life can be for a wild animal infested with ticks, fleas, worms, etc.; especially those living in forests and swamps. These are the only living creatures that, if I had the power to do so, I would terminate from existence.
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Post by OldGreenGrolar on Jul 9, 2021 6:52:45 GMT -5
The only living things that I hate are the parasites. "Parasitism is a kind of symbiosis, a close and persistent long-term biological interaction between a parasite and its host." It's difficult for me to even imagine how difficult life can be for a wild animal infested with ticks, fleas, worms, etc.; especially those living in forests and swamps. These are the only living creatures that, if I had the power to do so, I would terminate from existence. It is interesting that most parasites are invertebrates. |
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Post by brobear on Jul 9, 2021 7:40:19 GMT -5
The only living things that I hate are the parasites. "Parasitism is a kind of symbiosis, a close and persistent long-term biological interaction between a parasite and its host." It's difficult for me to even imagine how difficult life can be for a wild animal infested with ticks, fleas, worms, etc.; especially those living in forests and swamps. These are the only living creatures that, if I had the power to do so, I would terminate from existence. It is interesting that most parasites are invertebrates. Yes; "Low-Lifes" |
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