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Genetic switch of parrot color diversity revealed

Genetic switch of parrot color diversity revealed

Nov. 5 () –

An international team of scientists published in the journal Science the discovery of a “switch” in parrots’ DNA that controls their wide range of colors.

“Parrots are unique birds in many ways, including the way they produce their vibrant diversity of colors,” explains Professor Simon Yung Wa Sin, co-author from the School of Biological Sciences at the University of Hong Kong (HKU).

“Parrots do their own thing when it comes to color,” add in a statement Dr. Roberto Arbore of BIOPOLIS-CIBIO and co-lead author of the study.

Although other birds also produce yellow and red feathers, parrots evolved unique pigments, called psittacofulvins (from ancient Greek “psittakós,” meaning parrot, and Latin “fulvus,” meaning reddish yellow). “Parrots combine these pigments with others to create vibrant yellows, reds and greens, which makes these animals some of the most colorful in nature“he says.

Parrots are common pets in millions of homes around the world and are prized for their color and intelligence. But for all their showiness, it was not well understood how these birds developed a unique way of creating their color palette.

“This is a great mystery for both scientists and bird lovers,” explains Professor Miguel Carneiro, lead author of BIOPOLIS-CIBIO, who adds: “and it relates to a key question for all of biology: How does diversity arise in nature?

To answer this fundamental question, scientists began by showing that, in all major lineages of parrots, the yellow and red feathers They correspond to two specific pigments that do not occur in other birds.

“Although there were some indications in the literature about the existence of two chemical forms of psittacofulvins, at first we had a hard time believing what we were seeing in the results, side by side, with complete clarity, for the first time. Only with genetic data did everything start to make sense“says Dr. Jindrich Brejcha from the Faculty of Sciences at Charles University in Prague, another of the first co-authors.

To delve deeper, the scientists focused on a species with natural red or yellow shapes, a phenomenon that is extremely rare in nature.

“The dusky lory is native to the jungles of New Guinea, but we had to drive a few kilometers from our laboratory in Portugal, as local certified breeders helped us obtain samples to study the color genetics in this species,” said Pedro Miguel Araújo of the University of Coimbra, who co-led the research, added: “The solution to our study was almost next door.”

The scientists discovered that only one protein controlled the color difference in lorises, a type of aldehyde dehydrogenase (or ALDH), essential “tools” for detoxification in complex organisms; For example, they contribute to the elimination of alcohol in the liver of humans.

Dr. Soraia Barbosa, also lead co-author of BIOPOLIS-CIBIO, explains: “Parrot feathers They found a way to ‘borrow’ this proteinusing it to transform red psittacofulvins into yellow.” According to the scientist, “This works like a dial, in which greater activity of the protein translates into a less intense red color.”

To understand the general role of this protein in controlling plumage color in other parrot species, scientists studied another parrot, the rosy-faced lovebird, a species that displays green (i.e., yellow containing psittacofulvin) and red spots. in the plumage.

“The rosy-faced lovebird is a family parrot that provides an excellent system to study the genes that determine color difference between the red and yellow plumage spots that contain psittacofulvin,” said Simon Yung Wa Sin, who led the team from HKU’s School of Biological Sciences, which included Dr. Alison Cloutier and research assistant Emily Shui Kei Poon.

They found that the same aldehyde dehydrogenase gene in lovebirds is expressed at high levels in yellow feathers containing psittacofulvin, but not in red ones. “When this gene is expressed at a high level, psittacofulvins turn from red to yellow,” explains Yung Wa Sin.

To demonstrate this simple marking mechanism, scientists turned to an even better-known parrot, the budgerigar, and, for the first time in the world, explored how individual cells turn different genes on or off throughout feather growth. identifying a small number of cells that use this detoxifying protein to control pigment conversion.

Final validation came when scientists genetically modified yeast with the parrot color gene. “Incredibly, our modified yeast produced parrot colors, demonstrating that this gene is sufficient to explain how parrots control the amount of yellow and red in their feathers,” says Professor Joseph C. Corbo, a professor at the University of Washington in St .Louis.

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