Wallabies are adorable marsupials with an appetite for greens and veggies, mainly hopping around Papua New Guinea and Australia. The majority of these animals naturally have a brown or gray coat, enabling them to blend in with their surroundings and avoid predators.
While brown is their most common color, sometimes a white albino wallaby can pop out, even when their mother has the regular-colored fur. This phenomenon was not well understood, and despite numerous reports in the wild scientists have not been able to look at the animals DNA and figure it out.
That changed when a pale-skinned wallaby was born at Noichi Zoo in Japan, giving scientists a perfect candidate to find out more about. Samples were taken from the marsupial to get to the bottom of this mysterious phenomenon.
Cracking the case of the coat color
There are multiple genes that influence albinism in different organisms. Scientists identified the mutated TYR gene as the culprit in the wallaby. 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. The mutated TYR gene in these cases couldn’t carry out its intended function to produce pigment.
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 good way to imagine this is the process of copying and pasting a word in the middle of a tweet, causing the end of the text to be over the limit and therefore not being able to 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 story of this gene has not been mapped out, Koga’s team has gathered some valuable information. These types of retroviral mutations are present in every organism, being predicted to make up eight percent of the human genome and are thought to be very important players in evolution.
The virus DNA in this example of the walb gene changed the organism’s coat color. These mutations can also 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 elements across multiple species, the more understanding we will gain about evolution and disease. In turn, this will lead to better medical treatment and patient outcomes.
Source study: Genome – An endogenous retrovirus presumed to have been endogenized or relocated recently in a marsupial, the red-necked wallaby