Stem-cell 'symphony' creates patterns in feathers

Complex and vibrant bird plumage inspired Darwin's concept of sexual selection as well as many a poem and painting. But feather patterns are not directly coded in DNA, and only now has it become clear how birds pull off the feat: it is the result of a tightly choreographed team effort involving stem cells.

The researchers who made the discovery say it could one day help us grow organs from scratch, without the need to put cells on scaffolds that provide the correct shape ? although others are sceptical.

Cheng-Ming Chuong from the University of Southern California in Los Angeles and colleagues found a collection of stem cells at the base of feather follicles that give rise to melanocytes: cells that produce the pigment melanin.

The find mirrors a similar discovery in mammalian hair follicles a decade ago. But hair colour is a one-dimensional property, changing only along the hair's length. In a feather, colour can vary in three dimensions to create stripes or spots in the barbs that can appear different depending on which side of the feather you observe them from.

Looking more closely at the stem cells, Chuong worked out how they are linked with such fine control over feather colour. The cells sit in a ring and work together to change the pattern of melanocytes from the front to the back of the feather follicle, from the centre to the outside of the follicle, and over time as the feather grows.

"Like a symphony"

These three variables interplay with a fourth: production of a peptide called agouti by a layer of peripheral pulp found within feather follicles. Agouti inhibits melanocytes and so generates white ? unpigmented ? regions in the feather. For complex patterns, all four of these variables are "choreographed" at once in an intricate sequence, says Chuong. "You have [something] like a symphony there," he says.

"I think it's a very significant piece of work," says Rick Sturm from the University of Queensland in Brisbane, an expert in human pigmentation. He says he is surprised at the level of stem cell complexity in feather follicles.

The underlying motivation in figuring out how feather patterns are created was to understand how stem cells create complex patterns at all, explains Chuong. "We believe the fundamental principles of organised patterns are shared in different organs."

Melissa Little, also at the University of Queensland, leads research on kidney morphogenesis ? how kidneys get their shape. She thinks it's a stretch to say that the new study will help efforts to grow complex organs.

"We're already asking, how do you get those complex structures?" she says. "I think it's a jump if they think this is applicable to different systems."

Chuong disagrees. "People can take stem cells and make lung cells but they can't make the shape [of a lung]," he says. This month, for example, new kidneys were grown in the lab from stem cells, but they had to be grown on a scaffold obtained from an existing kidney.

"Getting into the control of morphogenesis is really the frontier of stem cell science," says Chuong. "The pigment pattern here is being used because it is experimental and manipulable."

Journal reference: Science, DOI: 10.1126/science.1230374

If you would like to reuse any content from New Scientist, either in print or online, please contact the syndication department first for permission. New Scientist does not own rights to photos, but there are a variety of licensing options available for use of articles and graphics we own the copyright to.

Have your say

Only subscribers may leave comments on this article. Please log in.

Only personal subscribers may leave comments on this article

Subscribe now to comment.

All comments should respect the New Scientist House Rules. If you think a particular comment breaks these rules then please use the "Report" link in that comment to report it to us.

If you are having a technical problem posting a comment, please contact technical support.

Source: http://feeds.newscientist.com/c/749/f/10897/s/2b2c3e5a/l/0L0Snewscientist0N0Carticle0Cdn234390Estemcell0Esymphony0Ecreates0Epatterns0Ein0Efeathers0Bhtml0Dcmpid0FRSS0QNSNS0Q20A120EGLOBAL0Qonline0Enews/story01.htm

troy tulowitzki katie couric good morning america the rock vs john cena acm awards 2012 january jones ncaa final game reba mcentire