Brown giant pandas reappeared in Qinling Mountains. Could it be that relatives from Qizi’s hometown have come?

Produced by: Science Popularization China

Author: Zhao Jidong (Shaanxi Institute of Zoology)

Producer: China Science Expo

Editor's note: In order to decode the latest mysteries of life science, the China Science Popularization Frontier Science Project has launched a series of articles called "New Knowledge of Life", which selects cutting-edge achievements in the field of life science and interprets them in plain language as soon as possible. Let us delve into the world of life and explore infinite possibilities.

Recently, staff at Shaanxi Changqing National Nature Reserve discovered a brown giant panda from massive infrared camera data!

Wild brown giant panda photographed in the reserve

(Photo source: Shaanxi Changqing National Nature Reserve)

The Mystery of the Brown Panda

According to records, the first clear record of a brown giant panda was in 1985. Researchers found a dying giant panda in a river valley at an altitude of 1,200m in Foping County, Shaanxi Province. It was later diagnosed with enteritis. The ears, eye circles and hair on the limbs of this giant panda are reddish brown. Professor Pan Wenshi, a giant panda researcher, named it "Dandan". "Dan" is homophonic with "Dan", which means unique and also means that its hair is red.

The brown giant panda Dandan was found suffering from enteritis

(Image source: Document 1)

After "Dandan" was sent to the zoo for breeding, she soon married another male black and white giant panda named "Wanwan", but the offspring they gave birth to were all normal black and white.

Since Dandan was rescued, researchers have successively observed wild brown pandas in the Foping Nature Reserve and Changqing Nature Reserve in Shaanxi Province. Until the big star Qizi was discovered, this rare color of brown pandas once again aroused people's curiosity, and researchers are eager to solve the mystery of fur color change.

The "Qi Zai" who eats carrots

(Photo source: People's Daily Online reporter Sun Ting)

"Qizi" was still a baby when he was discovered. He was sent to the Shaanxi Rare Wildlife Rescue and Breeding Research Center for rescue. He currently lives in the Qinling Sibao Science Park in Zhouzhi County, Shaanxi Province. He is the only captive brown giant panda in the world.

When Qizai was first discovered, he was still a baby. Both his parents are wild giant pandas.

(Photo source: China Broadcasting Network)

Uncovering the secret of brown

Some people believe that brown giant pandas may be albinos. Recently, a research team from the Institute of Zoology, Chinese Academy of Sciences and Jiangxi Agricultural University used years of accumulated data and sequencing methods to uncover the secret of brown giant pandas.

Researchers have found that the brown and white hair of giant pandas is controlled by an autosomal recessive inheritance pattern , and the Bace2 gene mutation on chromosome 1 of giant pandas is the genetic basis for the change in hair color. Simply put, if two normal black and white giant pandas carry the brown hair gene (Bace2 +/-), they have a chance to produce brown and white offspring (Bace2 -/-), while homozygous black and white giant pandas (Bace2 +/+) cannot produce brown and white offspring.

Giant panda Bace2 wild-type homozygous or heterozygous individuals (above), giant panda Bace2 homozygous deletion individuals and their hair (below, Qizi)

(Image source: Document 2)

The researchers also used gene editing technology to knock out the genes in the homologous region of the experimental mice and found that the Bace2 gene deletion mutation would reduce the number of melanosomes in the mouse hair, causing the black mice's hair to turn brown.

Gene knockout mouse model reveals that Bace2 deficiency reduces the number of melanosomes in mouse hair

(Image source: Document 2)

Human albinism is divided into oculocutaneous albinism (OCA) and ocular albinism (OA). The former is an autosomal recessive inheritance, while the latter is an X-linked recessive inheritance. The specific classification and clinical manifestations are complex, and involve many mutant genes, which is different from the Bace2 gene deletion in brown giant pandas.

Children with albinism (right)

(Image source: VEER)

Human albinism is also accompanied by abnormal symptoms, such as lack of iris pigment, poor vision, photophobia, skin sensitivity to ultraviolet rays, etc. Some types of albinism are also accompanied by chronic inflammation or fibrosis of organs. After years of breeding, the giant panda "Qizi" is currently very healthy and no similar symptoms have been reported.

Among the bears, there is another type of bear with a special color. It is a subspecies of the American black bear - the Kermode bear, also known as the Spirit bear, that lives in the Great Bear Rainforest in Canada.

Spirit bear (Ursus americanus kermodei) living in Canada's Great Bear Rainforest

(Image source: circa1983)

Like brown giant pandas, spirit bears are not true albino animals. They are healthy, with normal pigmentation in their skin and eyes. Apart from their fur color, their other physiological functions are the same as those of black American black bears.

A spirit bear competing with its black counterpart for salmon

(Image credit: Paul Nicklen)

The white variant of the American black bear is caused by a mutation in the melanocortin receptor 1 (mc1r). Similarly, the white trait is also recessive, and both parents must carry the mutation to give birth to a white individual.

A female black bear with her two cubs, one of which is a spirit bear

(Photo source: Pacific Wild)

In the Great Bear Rainforest of North America, spirit bears have formed a stable population of white individuals, but the total number is only 400-1,200.

Spirit Bear Deep in the Great Bear Rainforest

(Image source: circa1983)

The local residents regarded the spirit bears as gods and avoided being disturbed by too many visitors, so the spirit bears were not discovered until modern scientific surveys. In 2016, the British Columbia government of Canada announced that 85% of the core area of ​​the Great Bear Rainforest would be permanently protected.

I don’t know when brown pandas will form a stable population in the wild, and then there will be more pandas to take color photos of!

References

[1]. Pan Wenshi. The Long Road. 1998. Jiangsu Science and Technology Press.

[2]. Guan D, Sun S, Song L, Zhao P, Nie Y, Huang X, Zhou W, Yan L, Lei Y, Hu Y, Wei F. Taking a color photo: A homozygous 25-bp deletion in Bace2 may cause brown-and-white coat color in giant pandas. Proceedings of the National Academy of Sciences, 2024, 121: e2317430121.

[3]. Brown Giant Panda Dandan[J]. Shaanxi Forestry, 2005(S1): 34.

[4]. Biography of Pandas. [Documentary]. Pan Wenshi; Lü Zhi. 2010. CCTV.com.

[5]. Ritland K, Newton C, Marshall HD. Inheritance and population structure of the white-phased "Kermode" black bear. Current Biology. 2001, 11(18): 1468-1472.

[6]. Kermode bear or spirit bear. (22 March, 2022). Bear Protection Network.