Scientists unravel the mystery of rare brown giant pandas
Scientists have uncovered the genetic reason behind the unique brown-and-white coat of the rare giant pandas found exclusively in China's Qinling Mountains. A study in the journal PNAS revealed that this coat color results from natural variation rather than inbreeding, which could aid in breeding these pandas in captivity, as the species is considered vulnerable.
Brown pandas' unique coat color linked to gene mutation
Led by Dr. Fuwen Wei and Dr. Dengfeng Guan, the study found that a 25-bp deletion in the Bace2 gene causes a distinct coat color. This mutation was present in two Qinling pandas but not in those from Sichuan province, where most giant pandas live. Wei stated that the genetic mutation is "more likely to be a result of natural variation rather than inbreeding," as Qizai, a captive brown panda, had unrelated parents.
Microscopy and transmission electron microscopy analysis
The team analyzed Qizai's fur using microscopy and transmission electron microscopy, comparing it to hair samples from three black-and-white pandas. They discovered that Qizai's brown fur had fewer and smaller melanosomes, which determine skin and hair pigment in mammals. Additionally, these melanosomes were more likely to be irregularly shaped, leading to the identification of the mutation responsible for the coat color.
CRISPR-Cas9 gene-editing tool confirms findings
To verify their findings, researchers used the CRISPR-Cas9 gene-editing tool to remove the genetic sequence causing the Bace2 gene mutation in 78 lab mice. This change reduced the number and size of melanosomes in the mice, resulting in light brown coat color. Wei explained that this confirms the deletion's potential to alter coat color in mammals, making it highly likely that the mutation affects brown pandas' coat color.
Implications for brown panda conservation and breeding
This study offers valuable insights into breeding rare brown pandas, which hold significant scientific and ornamental value. Tiejun Wang, an associate professor at the University of Twente who was not involved in the study, praised the team's efforts and called the discovery a "positive development" for those concerned about the species. Further research on brown pandas and knockout mouse models will provide more information on the functional effects of this mutation.
