Scientists identify gene that forms fur patterns in cats

From leopard spots to tiger stripes, the fur patterns in cats are among the most immediately recognizable marks in the animal kingdom.

Now, researchers have identified the gene behind these models.

Analysis of skin samples from cat embryos at different stages of development has helped experts at the HudsonAlpha Institute for Biotechnology in Huntsville, Alabama, explore the genetics behind the wide array of cat brands.

After birth, newborn cats, from the humble tabby to the spotted leopard, have the same pattern and coat color that they will have all their lives.

The team found that the signaling molecule encoded by the Dkk4 gene is behind the decorations of a variety of animals, such as leopards, tigers and cheetahs.

The differences in the expression of the molecule while the embryo is still developing lead to the variety of patterns produced during subsequent hair growth.

It might theoretically be possible to use this information to conceive cats with specific patterns, but the researchers caution against the idea.

“I’m not very keen on promoting a mechanism for people to make designer cats if it comes at the expense of animal health,” lead author Professor Gregory Barsh told New Scientist.

Analysis of skin samples from non-viable cat embryos at different stages of development has helped experts at the HudsonAlpha Institute for Biotechnology in Huntsville, Ala., Explore the genetics behind the wide array of cat brands

The evolution and process behind the beauty of wild and companion cats has long fascinated scientists, including the author of this new study, Professor Gregory Barsh.

The US-based expert wanted to track when these patterns start to develop and found that it was while the embryo was still developing.

Previous research has shown that color patterns in domestic cats appear during hair growth when groups of adjacent hair follicles produce different types of pigments.

However, the developmental process that determines whether a hair follicle produces black or yellow melanin remains uncertain.

Prof Barsh said: “From leopards to giraffes to zebras, the developmental biology of the self-organized color pattern in mammals is an unsolved mystery,” adding that “they are available in a variety of sizes. and a range of varied fur colors and patterns “.

“Black striped tigers on an orange or white background roam the grasslands of Southeast Asia and India.

“Spotted cheetahs hunt antelopes through the brush of Africa. Jaguars with their rosette-patterned coats stalk their prey throughout South America and Latin America.

“And domesticated cats of many colors and coat patterns bask in the sun in living rooms around the world.”

Different hues – such as black, brown, yellow, or even red – are known to appear when adjacent follicles produce particular melanin pigments.

But the process of their determination has remained unclear. In the study, the US team scanned skin samples from non-viable embryos from feral cats.

They were at different stages of development and would otherwise have been rejected, with genetic analysis of individual cells and proteins in sections of tissue revealing that the Dkk4 gene played the key role.

The shape and color of the resulting pattern during hair growth has been traced back to the signaling molecule of this gene.

Professor Barsh said the gene “had mutated in cats with patterns checked”.

The breeds, known as the Abyssinian or the Servaline Savannah, have a salt and pepper coat instead of the traditional stripes or spots.

“Complex color patterns are a defining aspect of morphological diversity in cats,” said Prof Barsh, adding that “early in development we identify stripe-like alterations in the thickness of the epidermis preceded by of a pre-model of gene expression “.

He added: “Our results provide a molecular understanding of how the leopard got its spots. They suggest that similar mechanisms underlie the periodic color pattern and hair follicle spacing and identify targets for various pattern variations in other mammals.

For example, cheetahs are born with the same number of spots as they will be when they are adults. They just get bigger.

After birth, newborn cats, from the humble tabby to the spotted leopard or tiger (pictured), have the same pattern and coat color that they will have all their lives. Image bank

Intricate arrangements of alternating patches of light and dark hair, as seen in a cheetah, jaguar, or ocelot, are called periodic color patterns.

They are difficult to study because there is no real equivalent in model organisms.

Professor Barsh, an expert in animal morphology, said: “The genes that control simple color variation, like albinism or melanism, are mostly the same in all mammals.

“However, the biology underlying the mammalian color model has long been a mystery, one in which we have now gained new knowledge using domestic cats.”

The Nature Communications study sheds new light on rosette-shaped markings on leopards and stripes on tigers.

Dr Chris Kaelin, senior scientist at Alpha Hudson, said: “Our analysis identifies a network of molecules involved in pattern formation.

“Several of the molecules, including Dkk4, are known to work in a coordinated fashion as activators and inhibitors, just as Alan Turing predicted 70 years ago.”

Lab member Dr Kelly McGowan said: “Our results suggest that even before pigment-producing melanocyte cells enter the epidermis, the cells are predestined to signal a specific fur color.

“By understanding the window of development and the type of cell in which the establishment of color patterns occurs, we were able to deepen and discover the molecules involved in pattern development. “

Previous work has shown that coat color genes are involved in many other important biological pathways, some of which are relevant to human health.

Dr Kaelin added, “Our findings paved the way for understanding the onset of biodiversity on an evolutionary timescale – the genetic differences that are responsible for tiger stripes, cheetah spots and leopard rosettes. .

“As the work of Rudyard Kipling suggests, these fundamental questions inspire appreciation of natural diversity among a large audience in a way that discussions of conservation practices do not. ‘

The results were published in the journal Nature Communications.