[CAT] "One way to skin a cat – same genes behind blotches of tabbies and king cheetahs"

[rfmcdonald]

Not Exactly Rocket Science's Ed Yong writes about the latest discoveries regarding the genetics of the patterns of cats' coats. It turns out that the same genes define coat patterns across the felid family.

Two teams of scientists, led by Greg Barsh from the HudsonAlpha Institute for Biotechnology and Stanford University, and Stephen O’Brien from the Frederick National Laboratory for Cancer Research have discovered the gene behind the king cheetah’s ink-stains. And it’s the same gene that turns a mackerel-striped tabby cat into a blotched “classic” one.

Back in 2010, Eduardo Eizirik, one of O’Brien’s team, found a small region of DNA that seemed to control the different markings in mackerel and blotched tabbies. But, we only have a rough draft of the cat genome, they couldn’t identify any specific genes within the area. The study caught the attention of Barsh, who had long been interested in understanding how cats get their patterns, from tiger stripes to leopard rosettes. The two teams started working together.

Christopher Kaelin and Xing Xu focused on the region that Eizirik had identified, using DNA samples taken from Californian feral cats that had been captured for sterilisation. By comparing mackerel and blotched individuals, the team found one gene that was responsible for the different markings. They dubbed it Taqpep. All blotched tabbies have one of two critical mutations in both their copies of Taqpep, while all mackerel cats have one or two unblemished versions.

Taqpep is also responsible for the king cheetah’s unmistakeable coat. Kaelin and Xu sequenced the gene in Kgosi, a captive king cheetah, and found another mutation in Taqpep, one that greatly enlarges the protein encoded by the gene.

Kaelin got in touch with Ann van Dyk, the woman who first identified that king cheetahs were a mutant version of the regular ones. She runs a cheetah conservation centre in South Africa that’s Kgosi, and all other captive kings, came from. By analysing all of her cheetahs, van Dyk confirmed that Kgosi’s Taqpep mutation is found in all the kings, and none of the 217 wild spotted cheetahs do.

Yong writes at length. Most interestingly to me, the research suggests that a theory of Alan Turing on animal coat patterns might be accurate.

[D]iffusing molecules are central to a longstanding explanation for animal patterns. Back in 1952, Alan Turing, the legendary computer scientist and code-breaker, suggested that animal skins could produce beautiful complex patterns through a lively tango between two molecules – an activator and an inhibitor. Both diffuse throughout the skin, and react with each other. Over short distances, the activator reinforces itself, but over longer distances, the inhibitor blocks it. Depending on how quickly they spread and how strongly they interact, they can produce everything from spots to blotches.

Scientists have tested Turing’s “reaction-diffusion” ideas in many different animals, but it has been next to impossible to find the actual activators or inhibitors. Barsh thinks that Taqpep (or rather, Tabulin) may be one of them, and the team is now looking into it further.

Wired Science's Brandom Keim has more.