Wallabies are adorable marsupials with an appetite for greens and veggies. The majority of these animals can be found hopping around Papua New Guinea or Australia and naturally have a brown or gray coat, enabling them to blend in with their surroundings and avoid predators.
While brown wallabies are the most common, a white albino baby can occasionally pop out—even when their mother has regular-colored fur! Despite numerous reports of these pale-coated creatures in the wild, up until recently, the phenomenon was not well understood. This is due to scientists not being able to get a close enough look at these rare wallabies’ DNA to properly investigate the genetic culprit.
That changed when a healthy, pale-skinned wallaby was born at Noichi Zoo in Japan. The birth of this little one provided researchers with the perfect chance to find out more. Samples were taken from the marsupial to get to the bottom of this mystery.
Cracking the case of the coat color
In different animals, there are a range of genes that influence the chance of being born with albinism. Through a series of genetic tests, scientists were able to identify the mutated TYR gene as the reason behind wallaby albinism.
Previous studies have also associated this gene with albinism in humans, certain llamas, mice, cats, donkeys, and more. TYR has a role in producing melanin, the pigment that controls skin, hair, and eye color. When a mutation appears in this gene, it cannot carry out its intended function to produce pigment, resulting in the pale complexions we associate with the disorder.
When the scientists looked at exactly what was going on in the wallaby genome, they found something unusual. An extra DNA fragment that had inserted itself right in the place where the gene was supposed to be, removing two-thirds of its function. A great way to understand this is to imagine you copied and pasted a sentence in the middle of a tweet. The extra words would push the end of the text over the limit and therefore not be included in the post.
Where did the DNA come from?
The source of this insertion mutation actually comes from a type of virus called a retrovirus. The organism sneakily inserted its genetic material into the wallaby to trick the host into replicating its DNA for it. More details are discussed in the paper published in Genome.
“We found this inserted fragment in a wallaby, which we fittingly named walb,” mentions Akihiko Koga, who led the research team at Kyoto University.
Why is this research important?
While the full history and impact of this mutated gene have not yet been figured out, Koga’s team has gathered some valuable information. These types of mutations are present in every animal, including humans! Retroviral DNA is predicted to make up eight percent of the human genome and is thought to have played an extremely critical role in evolution.
The viral DNA in this example of the walb gene changed the organism’s coat color, making it easier for predators to spot. However, these mutations can cause much bigger problems in other places. Researchers suspect that retroviral insertions may be to blame for many unexplained diseases, including inflammatory and neurological conditions.
The more information we have about these genetic elements across multiple species, the deeper our understanding of evolution and disease can grow. In turn, this will lead to the advancement of medical treatments and patient outcomes.
Source study: Genome – An endogenous retrovirus presumed to have been endogenized or relocated recently in a marsupial, the red-necked wallaby
