Study Explaining Diversity of Color Patterns in Feathers Published in Science

Birds, with their beautiful and varied plumage, are a class of animal that comprises one of the largest numbers of species. Yet, scientists have long been unable to explain the reason birds were able to evolve such an endless variety of color patterns in their feathers.

Using the black-feathered Taiwan Country Chicken as a subject, an interdisciplinary team of NTU researchers discovered that melanocyte stem cells are concealed at the base of a feather. They also found that these stem cells have a horizontallydistributed, ring-like arrangement that allows for the flexible regulation of pigment patterns both temporally and spatially. This research finally explains the reason behind the wondrous diversity of pigment patterning in bird plumage and how feathers achieve pattern variations from the tip to the base and from left to right.

The team’s outstanding findings were published in the article, “Topology of Feather Melanocyte Progenitor Niche Allows Complex Pigment Patterns to Emerge,” in the worldrenowned journal Science this past April.

One of the authors of this study, Prof. Sung-Jan Lin of the Institute of Biomedical Engineering, pointed out that the evolution of feathers commenced during the Jurassic period and that it was dinosaurs that evolved the first feathers before going on to evolve gradually into modernday birds. We know now that dinosaurs already displayed a diversity of color patterns in their plumage during the Jurassic period, but what was the crucial transformation that allowed later feathers to develop the beautiful variety of colors and patterns we see today?

This study was conducted by researchers from the NTU Research Center for Developmental Biology and Regenerative Medicine under the leadership of Honorary Director Cheng-Ming Chuong. Scientists at the University of Southern California and Indiana University School of Medicine as well as independent research scholars in the United States also cooperated on the project. National Chung Hsing University played a vital role, as well, by providing its special breed of Taiwanese chicken.

Many scientists attempted to answer this question during the previous century, however none of them succeeded in arriving at an acceptable conclusion. This failure was primarily due to the fact that melanocyte stem cells in feathers lack pigment. This means that common biopsies cannot be used to identify these stem cells or their stem cell niche.

Prof. Lin and his research team used methods derived from the study of stem cells and molecular biology to develop molecular probes and markers that permitted them to find evidence of melanocyte stem cells in the black-feathered Taiwan Country Chicken. The investigators discovered that melanocyte stem cells are hidden in non-pigmented epidermis at the base of a feather. This was a finding that overturned the old concepts that scholars had held during the last century. Moreover, the team’s discovery revealed the importance of topobiology for the regulation of stem cells.