Meet Qizai: not only is he thoroughly friend-shaped, but he’s also quite the mystery man. The giant panda is one of just seven brown and white members of the species ever reported, and the only one in captivity. The reason for this unusual coloring had long eluded scientists – but with the help of genetics, the mystery now appears to be solved.
A team of researchers set out to determine whether any differences in the DNA of brown pandas could explain their unusual fur color. As part of this genetic detective work, they sequenced the genomes of 35 giant pandas; this included two brown pandas (one of whom was our boy Qizai), and the two family trios they belonged to, as well as regular black and white pandas.
In comparing the resulting sequences, the team identified what they believe to be the gene involved: Bace2. This gene encodes an enzyme that’s involved in chopping up amyloid precursor protein, a molecule perhaps best known for its role in Alzheimer’s disease.
The brown pandas were found to have two identical copies of a particular variant of Bace2, both missing 25 base pairs (the building blocks of DNA, often simply represented by letters), suggesting it could play a role in their fur color.
The researchers didn’t stop there though. In search of validation for their findings, they also sequenced the DNA of another 192 black and white pandas, with the analysis revealing that none had two copies of that same variation in Bace2. When they further created mice with the mutation, using a method called CRISPR-Cas9, the resulting mice had light fur.
But how does this mutation lead to brown pandas like Qizai?
“Our investigation revealed that this mutation reduced the number and size of melanosomes of the hairs in knockout mice and possibly in the brown panda, further leading to the hypopigmentation,” the researchers write in their paper.
Melanosomes are specialized structures within cells – the fancy term being organelles – responsible for the production and storage of melanin, a type of pigment that can determine the color of skin and hair or fur.
Thus, a mutation in Bace2 might affect melanosomes in pandas, and consequently give them brown and white fur instead of black and white. The next step for the researchers is to investigate this theory and figure out how it might work – Qizai is still keeping some cards close to his chest.
That being said, the current research is a pretty big first step in solving the puzzle of these rare pandas. Qizai the brown panda might have lost a bit of his mystery, but he’s definitely clawed something back in scientific progress.
The study is published in the journal PNAS.
Source Link: Mystery Of World’s Only Captive Brown And White Panda Solved With Genetics
