© TIBETAN MASTIFF 2024
Powered By Tibetan Mastiff owners of AU/NZ 2024

Did you know?

The Dalai Lama had eight Tibetan Mastiffs guarding his summer residence at Norblinka - two dogs at each entrance. The earliest record of these dogs in England was in 1828 when one was presented to London Zoo - and then the Viceroy of India sent one to Queen Victoria in 1847. In 1970, the breed found another role when Nepalese drug smugglers used them to ship illegal drugs into the US in the bottom of their dog crates. Strangely customs officials weren’t particularly keen to search them!

Tibetan Mastiffs in Australia

The first Tibetan Mastiff pair were imported into Australia in early 1983 by Dick and Pauline Leeton of South Australia. A light gold male (Ausables Tudorhill Dalai Dallas) and a black and tan bitch (Ausables Tudorhill Lama Panda). These dogs spent 12 months in quarantine in England prior to coming to Australia and were shown extensively during that time. They were the first Tibetan Mastiffs to appear at Crufts in 50 years and both won first in their respective classes. Shortly after this a second bitch, black in colour (Qassaba Ausables Matilda Tilly), was imported from the UK. These three formed the strong basis of the Tibetan Mastiff breed in Australia. Time immemorial Tibet has always been so isolated, that it’s impossible to say how or when TMs came to be. We know that for millennia they were the mighty guardians of the Himalayas, and it’s thought that they’re the progenitor of all modern mastiffs. Evidence suggests that early travellers to Tibet were sometimes given these giants as gifts, which were used to create the mastiff breeds of the Middle East and Europe.

News

TIBETAN

MASTIFF

-

Majestic

and

Exotic

Canine

that

are

sure

to

take

your

breath

away!

A breed unique in its own right

The Tibetan Mastiff exhibits a unique combination of physical traits that make it stand out. From its beautiful colours and long coat, to its strong and noble stance, the Tibetan Mastiff is truly a sight to behold.

Unconditional love and devotion

As loving companions, Tibetan Mastiffs are known for their loyalty and devotion to their family. They're intelligent dogs that will do whatever they can to please their owners, making them great family pets.

A personality all their own

Tibetan Mastiffs are independent thinkers who have minds of their own. They can be stubborn at times but still remain gentle and loving with their humans. They're also fearless guardians who will protect their pack with no hesitation. The Tibetan with its large size, long coat, and beautiful tail, its sure to turn heads wherever he goes. But if that's all you're looking for in a dog, the Tibetan Mastiff is not the breed for you. The Tibetan Mastiff is a loving, gentle, and patient breed that has been working closely with humans for centuries. This has made him very sophisticated in the ways he understands people. He's a hard worker, fearless, and loyal, and his large size and substance make him the perfect guard dog. Centuries of breeding for that specific task has perfected him as a protector.

Genetic Study on High-Altitude Adaptation

A recent study has uncovered fascinating details about the Tibetan Mastiff's ability to survive in the harsh, high-altitude environments of the Himalayas. Genetic analysis revealed that Tibetan Mastiffs have specific mutations inherited from Tibetan wolves, enhancing their ability to absorb and release oxygen more effectively. These genetic traits allow them to thrive in environments where other breeds would struggle due to low oxygen levels. The study found that these mutations significantly affect hemoglobin production, making Tibetan Mastiffs highly suited to high-altitude living, a characteristic that has helped define the breed over thousands of years. (livescience.com) .

Crufts 2024 and Tibetan Mastiffs

The 2024 Crufts show included notable appearances by Tibetan Mastiffs, demonstrating their enduring appeal and continued presence in competitive dog shows. The event featured the breed's distinct qualities, showcasing their powerful, independent nature and impressive guarding instincts. This exposure helps maintain interest in the breed and reinforces their reputation as one of the world's most formidable guardian dogs. (Archaeology Magazine) .

Survival and Breeding with Tibetan Wolves

Further research indicated that at some point in their evolutionary history, Tibetan Mastiffs interbred with Tibetan wolves. This interbreeding passed on crucial genetic traits that enhance their endurance and physical resilience at high altitudes. These unique adaptations make Tibetan Mastiffs not only symbolically linked to their wild counterparts but also genetically suited to the challenging environments of their origin. (https://www.science.org/) . These findings underline the importance of preserving the breed's traditional traits while appreciating its extraordinary evolutionary journey. For more information on the genetic study and other news, you can explore additional details on the Live Science website .

Focus on Preservation Amidst Modern

Challenges

Efforts by breed clubs and dedicated breeders continue to focus on preserving the Tibetan Mastiff’s historical traits amidst modern challenges, including the commercialization and cross-breeding seen in some regions. Organizations like ATMA stress the importance of breeding responsibly to maintain the integrity and authenticity of the Tibetan Mastiff, ensuring that its ancient qualities remain intact for future generations. (Tibetan Mastiff Org) . These updates reflect the ongoing commitment to maintaining the Tibetan Mastiff’s legacy as a majestic and resilient breed. For more detailed information on these topics, you can explore the American Tibetan Mastiff Association and related studies on high-altitude adaptation.

Tibetan Mastiff Behaviour and Training:

Tibetan Mastiffs are serious, dignified, and independent dogs. They require an assertive leader who can provide consistent training and socialization to manage their protective instincts. The breed is naturally territorial and can be aloof with strangers, making early socialization critical to prevent excessive aggression. While they are calm and quiet indoors, they excel in outdoor environments where they can patrol their territory. Tibetan Mastiffs are not ideal for first-time owners due to their strong-willed nature and need for space and supervision. (Your Pure- bred Puppy).

The Tibetan Mastiff and the Kekhor

In the highlands of Tibet, it’s not uncommon to see a Tibetan Mastiff wearing a traditional collar known as a Kekhor or ske’kor. This unique accessory combines the words “ske” (neck) and “kor” (circle), reflecting its function as a neck collar. Made from yak hair dyed red—though some can be black, yellow, or multi-colored—the Kekhor is more than just a ceremonial decoration. Some collars even feature bells or ancient elements like Yak caudal vertebras to reinforce their structure, highlighting their historical significance. Ancient Origins and Practical Uses The Kekhor has a long and storied history in Tibetan culture. The great Erdene Zuu temple, built in 1585 by Abtai Sain Khan, includes frescoes depicting dogs wearing Kekhors, indicating their ancient origins. Traditionally, the Kekhor serves several important purposes: Breed Identification: The Kekhor helps identify a dog as a purebred Tibetan Mastiff, a vital feature in areas where these dogs play critical roles as guardians. Visual Recognition: From a distance, the Kekhor helps owners distinguish their dogs from wildlife, such as bears, due to the collar’s distinct appearance. Intimidation of Predators: The large, fluttering yak hair makes the dog appear even more imposing, potentially deterring predators. In the wild, Tibetan Mastiffs face threats from snow leopards and wolves, and the Kekhor can make them look more formidable. Neck Protection: Beyond aesthetics, Tibetan owners believe that the Kekhor offers extra protection to the dog’s neck during attacks from predators, acting as a barrier against bites. Modern Appeal and Considerations Kekhors are not just functional; they are also visually stunning and sometimes used as decorative elements in homes. Although available commercially, it’s essential for buyers to be aware of their authentic nature. Freshly made Kekhors often have a strong odor reminiscent of yaks in a barnyard, which can be quite pungent. Many people choose to air out new Kekhors outdoors until the scent neutralizes.

The First Tibetan Mastiff in America

While the Tibetan Mastiff was officially recognized by the American Kennel Club (AKC) in 2007, the breed's presence in the United States dates back to much earlier, with one of the most notable introductions involving President Dwight D. Eisenhower. In the 1950s, the Dalai Lama gifted Eisenhower a 10-month-old male and an 8-month-old female Tibetan Mastiff as a diplomatic gesture. The Dalai Lama, who famously kept eight Tibetan Mastiffs to guard his summer residence in Norbulinka, shared his appreciation for the breed through this rare and prestigious gift. However, Eisenhower, not in a position to care for the dogs, passed them on to a U.S. senator. The senator raised the dogs and eventually gifted one to the renowned explorer Lowell Thomas. These dogs, described as voracious eaters consuming “four pounds of fresh meat at each meal,” became foundational ancestors of many Tibetan Mastiffs in the United States today. This early entry into American soil not only highlighted the breed’s significance as a diplomatic gift but also set the stage for the Tibetan Mastiff’s gradual recognition and popularity in the Western world. Their unique blend of loyalty, guarding instincts, and ancient heritage continues to captivate enthusiasts and dog lovers alike. Tibetan Mastiff by Judith Stein – This piece of history is chronicled by Judith Stein, an expert who has documented the breed's journey and significance, reflecting on how these majestic guardians made their mark far from their Himalayan origins.
BONO - Temzin
MOMOA - Temzin
MOMOA - Temzin
THUNDER - Temzin

Mindful, Present

We deeply respect traditional knowledge about Tibetan breeds, especially insights from His Eminence, the 5th Gonsar Rinpoche. Born in Shigatse, Tibet in 1949, Rinpoche is a spiritual leader in the Gonsar Tulku lineage and a practitioner of the Hayagriva Tantras. According to Rinpoche, black and tan Tibetan Mastiffs are particularly favored as guard dogs due to their intimidating appearance. The dark coloring is believed to deter intruders with a strong “don’t even think about entering this house” impact. The tan spots above their eyes, known as “four eyes,” give the illusion that the dog is always alert, even while resting, and are believed to possess mystical properties that protect against evil spirits, such as demons. These spiritual beliefs reinforce the breed’s role as a guardian not just of homes, but also of the spiritual well-being of its owners. Rinpoche’s teachings highlight the importance of these colors and markings in Tibetan culture, emphasizing that they are more than mere aesthetics; they are symbols of the dog’s protective nature, both physically and metaphysically. The Tibetan Mastiff’s role extends beyond guarding property to include safeguarding the spiritual space of its surroundings. This belief in the mystical protective power of the Tibetan Mastiff continues to influence color preferences in the breed today, alongside the AKC’s recognized colors of black, brown, blue/grey, and gold, all with or without tan markings. The Tibetan Mastiff’s imposing presence, enhanced by the Kekhor collars and its distinctive coloring, not only serves as a visual deterrent to potential intruders but also connects the breed deeply with Tibetan spiritual and cultural traditions. These dogs are seen as more than guardians; they are living symbols of ancient wisdom and protective energy, cherished in their homeland and beyond.

For millennia, the massive Tibetan Mastiff has laid literal claim to the label “top dog.”

The fierce breed, which boasts a lionesque mane and can reach 70 kgs, has long protected Himalayan flocks of sheep from Tibetan wolves and other predators lurking upward of 15,000 feet above sea level — heights no other domestic breed can survive. Prior research suggests the Tibetan mastiff took an evolutionary shortcut by breeding with the Tibetan wolf, which had already adapted to the altitude by evolving more efficient hemoglobin: the protein that snares oxygen in the bloodstream and distributes it to organs. The University of Nebraska–Lincoln’s Jay Storz, Tony Signore and colleagues have now determined that sleeping with the enemy granted the Tibetan mastiff a hemoglobin architecture that catches and releases oxygen about 50% more efficiently than in other dog breeds. Signore reached the conclusion after testing the Tibetan mastiff hemoglobin against that of multiple domestic breeds, including Storz’s own half-Great Pyrenees, half-Irish wolfhound. “At altitude, the problem is taking in oxygen, because there’s just less of it,” said Signore, a postdoctoral researcher working in Storz’s lab. “If you think of hemoglobin like an oxygen magnet, this magnet’s just stronger.” The Nebraska researchers, who collaborated with colleagues at Qinghai University in China, already knew that the Tibetan mastiff’s hemoglobin included changes in two amino acids — slight modifications to the structure of the protein — that are present in the Tibetan wolf but absent in all other dog breeds. By engineering and then testing hemoglobins that contained both amino acid mutations vs. just one or the other, the team discovered that both mutations are crucial to the adaptive change in hemoglobin performance. When either mutation was absent, the hemoglobin performed no differently than that of other dog breeds. “There had been no direct evidence documenting that, yes, these two unique mutations have some beneficial physiological effect that is likely to be adaptive at high altitude,” said Storz, professor of biological sciences and author of a recent book on hemoglobin. “What we’ve discovered is one of the reasons why the Tibetan mastiff is so different from other dogs. And that’s because it’s borrowed a few things from Tibetan wolves.” Those two amino acid mutations originate from a gene segment that the Tibetan wolf passed to the mastiff via cross-breeding. But the new study also suggests that the gene segment itself came from an inactive gene a so-called pseudo-gene that lay dormant in the wolf subspecies for probably thousands of years. At some point, the pseudo-gene segment harboring the two mutations was copied and pasted into the corresponding segment of a similar but active gene, which then reformatted the Tibetan wolf’s hemoglobin. Because those mutations came from an inactive gene one with no physiological effects on the wolf they weren’t initially subject to the pressures of natural selection. In this instance, though, the mutations just so happened to improve the oxygen-binding capacity of hemoglobin, raising the Tibetan wolf’s survival odds. That encouraged the passage of the gene segment through subsequent generations of the wolf and, eventually, to the Tibetan mastiff. “They wouldn’t have conferred any benefit under normal circumstances,” Storz said. “It was just (that) this conversion event occurred in an environmental context where the increase in hemoglobin-oxygen affinity would have been beneficial. So mutations that otherwise would have been either neutral or even detrimental actually had a positive fitness effect.” Storz said there are few other documented cases where an initially inconsequential or adverse mutation ultimately benefited an organism as its environment changed. And most such cases have involved experimental studies on micro-organisms in the lab. “This is a nice example of the effect involving vertebrate animals and the natural environment,” he said. The researchers reported their findings in the journal Molecular Biology and Evolution. Storz and Signore authored the study with Nebraska’s Hideaki Moriyama, associate professor of biological sciences, along with Qinghai University’s Ri-Li Ge, Ying-Zhong Yang, Quan-Yu Yang and Ga Qin. The team received support from the National Science Foundation and the National Institutes of Health under grant No. HL087216. NEWS.UNL.EDU By Scott Schrage | University Communication and Marketing
Powered By Tibetan Mastiff owners of AU/NZ 2024
KHAAN - Temzin
KHAAN - Temzin
TANE - Temzin
TANE - Temzin
© TIBETAN MASTIFF 2024
Powered By Tibetan Mastiff owners of AU/NZ 2024

Did you know?

The Dalai Lama had eight Tibetan Mastiffs guarding his summer residence at Norblinka - two dogs at each entrance. The earliest record of these dogs in England was in 1828 when one was presented to London Zoo - and then the Viceroy of India sent one to Queen Victoria in 1847. In 1970, the breed found another role when Nepalese drug smugglers used them to ship illegal drugs into the US in the bottom of their dog crates. Strangely customs officials weren’t particularly keen to search them!

Tibetan Mastiffs in Australia

The first Tibetan Mastiff pair were imported into Australia in early 1983 by Dick and Pauline Leeton of South Australia. A light gold male (Ausables Tudorhill Dalai Dallas) and a black and tan bitch (Ausables Tudorhill Lama Panda). These dogs spent 12 months in quarantine in England prior to coming to Australia and were shown extensively during that time. They were the first Tibetan Mastiffs to appear at Crufts in 50 years and both won first in their respective classes. Shortly after this a second bitch, black in colour (Qassaba Ausables Matilda Tilly), was imported from the UK. These three formed the strong basis of the Tibetan Mastiff breed in Australia. Time immemorial Tibet has always been so isolated, that it’s impossible to say how or when TMs came to be. We know that for millennia they were the mighty guardians of the Himalayas, and it’s thought that they’re the progenitor of all modern mastiffs. Evidence suggests that early travellers to Tibet were sometimes given these giants as gifts, which were used to create the mastiff breeds of the Middle East and Europe.

News

TIBETAN

MASTIFF

-

Majestic

and

Exotic

Canine

that

are

sure

to

take

your

breath

away!

A breed unique in its own right

The Tibetan Mastiff exhibits a unique combination of physical traits that make it stand out. From its beautiful colours and long coat, to its strong and noble stance, the Tibetan Mastiff is truly a sight to behold.

Unconditional love and devotion

As loving companions, Tibetan Mastiffs are known for their loyalty and devotion to their family. They're intelligent dogs that will do whatever they can to please their owners, making them great family pets.

A personality all their own

Tibetan Mastiffs are independent thinkers who have minds of their own. They can be stubborn at times but still remain gentle and loving with their humans. They're also fearless guardians who will protect their pack with no hesitation. The Tibetan with its large size, long coat, and beautiful tail, its sure to turn heads wherever he goes. But if that's all you're looking for in a dog, the Tibetan Mastiff is not the breed for you. The Tibetan Mastiff is a loving, gentle, and patient breed that has been working closely with humans for centuries. This has made him very sophisticated in the ways he understands people. He's a hard worker, fearless, and loyal, and his large size and substance make him the perfect guard dog. Centuries of breeding for that specific task has perfected him as a protector.

Genetic Study on High-Altitude Adaptation

A recent study has uncovered fascinating details about the Tibetan Mastiff's ability to survive in the harsh, high-altitude environments of the Himalayas. Genetic analysis revealed that Tibetan Mastiffs have specific mutations inherited from Tibetan wolves, enhancing their ability to absorb and release oxygen more effectively. These genetic traits allow them to thrive in environments where other breeds would struggle due to low oxygen levels. The study found that these mutations significantly affect hemoglobin production, making Tibetan Mastiffs highly suited to high-altitude living, a characteristic that has helped define the breed over thousands of years. (livescience.com) .

Crufts 2024 and Tibetan Mastiffs

The 2024 Crufts show included notable appearances by Tibetan Mastiffs, demonstrating their enduring appeal and continued presence in competitive dog shows. The event featured the breed's distinct qualities, showcasing their powerful, independent nature and impressive guarding instincts. This exposure helps maintain interest in the breed and reinforces their reputation as one of the world's most formidable guardian dogs. (Archaeology Magazine) .

Survival and Breeding with Tibetan Wolves

Further research indicated that at some point in their evolutionary history, Tibetan Mastiffs interbred with Tibetan wolves. This interbreeding passed on crucial genetic traits that enhance their endurance and physical resilience at high altitudes. These unique adaptations make Tibetan Mastiffs not only symbolically linked to their wild counterparts but also genetically suited to the challenging environments of their origin. (https://www.science.org/) . These findings underline the importance of preserving the breed's traditional traits while appreciating its extraordinary evolutionary journey. For more information on the genetic study and other news, you can explore additional details on the Live Science website .

Focus

on

Preservation

Amidst

Modern

Challenges

Efforts by breed clubs and dedicated breeders continue to focus on preserving the Tibetan Mastiff’s historical traits amidst modern challenges, including the commercialization and cross-breeding seen in some regions. Organizations like ATMA stress the importance of breeding responsibly to maintain the integrity and authenticity of the Tibetan Mastiff, ensuring that its ancient qualities remain intact for future generations. (Tibetan Mastiff Org) . These updates reflect the ongoing commitment to maintaining the Tibetan Mastiff’s legacy as a majestic and resilient breed. For more detailed information on these topics, you can explore the American Tibetan Mastiff Association and related studies on high-altitude adaptation.

The Tibetan Mastiff and the Kekhor

In the highlands of Tibet, it’s not uncommon to see a Tibetan Mastiff wearing a traditional collar known as a Kekhor or ske’kor. This unique accessory combines the words “ske” (neck) and “kor” (circle), reflecting its function as a neck collar. Made from yak hair dyed red—though some can be black, yellow, or multi-colored—the Kekhor is more than just a ceremonial decoration. Some collars even feature bells or ancient elements like Yak caudal vertebras to reinforce their structure, highlighting their historical significance. Ancient Origins and Practical Uses The Kekhor has a long and storied history in Tibetan culture. The great Erdene Zuu temple, built in 1585 by Abtai Sain Khan, includes frescoes depicting dogs wearing Kekhors, indicating their ancient origins. Traditionally, the Kekhor serves several important purposes: Breed Identification: The Kekhor helps identify a dog as a purebred Tibetan Mastiff, a vital feature in areas where these dogs play critical roles as guardians. Visual Recognition: From a distance, the Kekhor helps owners distinguish their dogs from wildlife, such as bears, due to the collar’s distinct appearance. Intimidation of Predators: The large, fluttering yak hair makes the dog appear even more imposing, potentially deterring predators. In the wild, Tibetan Mastiffs face threats from snow leopards and wolves, and the Kekhor can make them look more formidable. Neck Protection: Beyond aesthetics, Tibetan owners believe that the Kekhor offers extra protection to the dog’s neck during attacks from predators, acting as a barrier against bites. Modern Appeal and Considerations Kekhors are not just functional; they are also visually stunning and sometimes used as decorative elements in homes. Although available commercially, it’s essential for buyers to be aware of their authentic nature. Freshly made Kekhors often have a strong odor reminiscent of yaks in a barnyard, which can be quite pungent. Many people choose to air out new Kekhors outdoors until the scent neutralizes.
BONO - Temzin

Tibetan Mastiff Behaviour and Training:

Tibetan Mastiffs are serious, dignified, and independent dogs. They require an assertive leader who can provide consistent training and socialization to manage their protective instincts. The breed is naturally territorial and can be aloof with strangers, making early socialization critical to prevent excessive aggression. While they are calm and quiet indoors, they excel in outdoor environments where they can patrol their territory. Tibetan Mastiffs are not ideal for first-time owners due to their strong- willed nature and need for space and supervision. (Your Pure-bred Puppy).

The First Tibetan Mastiff in America

While the Tibetan Mastiff was officially recognized by the American Kennel Club (AKC) in 2007, the breed's presence in the United States dates back to much earlier, with one of the most notable introductions involving President Dwight D. Eisenhower. In the 1950s, the Dalai Lama gifted Eisenhower a 10-month-old male and an 8-month- old female Tibetan Mastiff as a diplomatic gesture. The Dalai Lama, who famously kept eight Tibetan Mastiffs to guard his summer residence in Norbulinka, shared his appreciation for the breed through this rare and prestigious gift. However, Eisenhower, not in a position to care for the dogs, passed them on to a U.S. senator. The senator raised the dogs and eventually gifted one to the renowned explorer Lowell Thomas. These dogs, described as voracious eaters consuming “four pounds of fresh meat at each meal,” became foundational ancestors of many Tibetan Mastiffs in the United States today. This early entry into American soil not only highlighted the breed’s significance as a diplomatic gift but also set the stage for the Tibetan Mastiff’s gradual recognition and popularity in the Western world. Their unique blend of loyalty, guarding instincts, and ancient heritage continues to captivate enthusiasts and dog lovers alike. Tibetan Mastiff by Judith Stein This piece of history is chronicled by Judith Stein, an expert who has documented the breed's journey and significance, reflecting on how these majestic guardians made their mark far from their Himalayan origins.
MOMOA - Temzin
THUNDER - Temzin

Mindful, Present

We deeply respect traditional knowledge about Tibetan breeds, especially insights from His Eminence, the 5th Gonsar Rinpoche. Born in Shigatse, Tibet in 1949, Rinpoche is a spiritual leader in the Gonsar Tulku lineage and a practitioner of the Hayagriva Tantras. According to Rinpoche, black and tan Tibetan Mastiffs are particularly favored as guard dogs due to their intimidating appearance. The dark coloring is believed to deter intruders with a strong “don’t even think about entering this house” impact. The tan spots above their eyes, known as “four eyes,” give the illusion that the dog is always alert, even while resting, and are believed to possess mystical properties that protect against evil spirits, such as demons. These spiritual beliefs reinforce the breed’s role as a guardian not just of homes, but also of the spiritual well-being of its owners. Rinpoche’s teachings highlight the importance of these colors and markings in Tibetan culture, emphasizing that they are more than mere aesthetics; they are symbols of the dog’s protective nature, both physically and metaphysically. The Tibetan Mastiff’s role extends beyond guarding property to include safeguarding the spiritual space of its surroundings. This belief in the mystical protective power of the Tibetan Mastiff continues to influence color preferences in the breed today, alongside the AKC’s recognized colors of black, brown, blue/grey, and gold, all with or without tan markings. The Tibetan Mastiff’s imposing presence, enhanced by the Kekhor collars and its distinctive coloring, not only serves as a visual deterrent to potential intruders but also connects the breed deeply with Tibetan spiritual and cultural traditions. These dogs are seen as more than guardians; they are living symbols of ancient wisdom and protective energy, cherished in their homeland and beyond.

For millennia, the massive Tibetan Mastiff has

laid literal claim to the label “top dog.”

The fierce breed, which boasts a lionesque mane and can reach 70 kgs, has long protected Himalayan flocks of sheep from Tibetan wolves and other predators lurking upward of 15,000 feet above sea level heights no other domestic breed can survive. Prior research suggests the Tibetan mastiff took an evolutionary shortcut by breeding with the Tibetan wolf, which had already adapted to the altitude by evolving more efficient hemoglobin: the protein that snares oxygen in the bloodstream and distributes it to organs. The University of Nebraska–Lincoln’s Jay Storz, Tony Signore and colleagues have now determined that sleeping with the enemy granted the Tibetan mastiff a hemoglobin architecture that catches and releases oxygen about 50% more efficiently than in other dog breeds. Signore reached the conclusion after testing the Tibetan mastiff hemoglobin against that of multiple domestic breeds, including Storz’s own half-Great Pyrenees, half-Irish wolfhound. “At altitude, the problem is taking in oxygen, because there’s just less of it,” said Signore, a postdoctoral researcher working in Storz’s lab. “If you think of hemoglobin like an oxygen magnet, this magnet’s just stronger.” The Nebraska researchers, who collaborated with colleagues at Qinghai University in China, already knew that the Tibetan mastiff’s hemoglobin included changes in two amino acids slight modifications to the structure of the protein that are present in the Tibetan wolf but absent in all other dog breeds. By engineering and then testing hemoglobins that contained both amino acid mutations vs. just one or the other, the team discovered that both mutations are crucial to the adaptive change in hemoglobin performance. When either mutation was absent, the hemoglobin performed no differently than that of other dog breeds. “There had been no direct evidence documenting that, yes, these two unique mutations have some beneficial physiological effect that is likely to be adaptive at high altitude,” said Storz, professor of biological sciences and author of a recent book on hemoglobin. “What we’ve discovered is one of the reasons why the Tibetan mastiff is so different from other dogs. And that’s because it’s borrowed a few things from Tibetan wolves.” Those two amino acid mutations originate from a gene segment that the Tibetan wolf passed to the mastiff via cross-breeding. But the new study also suggests that the gene segment itself came from an inactive gene a so-called pseudo-gene that lay dormant in the wolf subspecies for probably thousands of years. At some point, the pseudo-gene segment harboring the two mutations was copied and pasted into the corresponding segment of a similar but active gene, which then reformatted the Tibetan wolf’s hemoglobin. Because those mutations came from an inactive gene one with no physiological effects on the wolf they weren’t initially subject to the pressures of natural selection. In this instance, though, the mutations just so happened to improve the oxygen-binding capacity of hemoglobin, raising the Tibetan wolf’s survival odds. That encouraged the passage of the gene segment through subsequent generations of the wolf and, eventually, to the Tibetan mastiff. “They wouldn’t have conferred any benefit under normal circumstances,” Storz said. “It was just (that) this conversion event occurred in an environmental context where the increase in hemoglobin-oxygen affinity would have been beneficial. So mutations that otherwise would have been either neutral or even detrimental actually had a positive fitness effect.” Storz said there are few other documented cases where an initially inconsequential or adverse mutation ultimately benefited an organism as its environment changed. And most such cases have involved experimental studies on micro-organisms in the lab. “This is a nice example of the effect involving vertebrate animals and the natural environment,” he said. The researchers reported their findings in the journal Molecular Biology and Evolution. Storz and Signore authored the study with Nebraska’s Hideaki Moriyama, associate professor of biological sciences, along with Qinghai University’s Ri-Li Ge, Ying-Zhong Yang, Quan-Yu Yang and Ga Qin. The team received support from the National Science Foundation and the National Institutes of Health under grant No. HL087216. NEWS.UNL.EDU By Scott Schrage | University Communication and Marketing
KHAAN - Temzin
KHAAN - Temzin
TANE - Temzin
TANE - Temzin