Birds of a feather may flock together, but the feathers of birds differ altogether.
New research from an international team led by USC scientists set out to learn how feathers developed and helped birds spread across the world. Flight feathers, in particular, are masterpieces of propulsion and adaptation, helping penguins swim, eagles soar and hummingbirds hover.
Despite such diversity, the feather shares a common core design: a one-style-fits-all model with option trims for specialized performance. This simplicity and flexibility found in nature holds promise for engineers looking for better ways to build drones, wind turbines, medical implants and other advanced materials.
Those findings, published today in Cell, offer an in-depth look at the form and function of a feather based on a comparative analysis of their physical structure, cellular composition and evolution. The study compares feathers of 21 bird species from around the world.
Weve always wondered how birds can fly in so many different ways, and we found the difference in flight styles is largely due to the characteristics of their flight feathers, said Cheng-Ming Chuong, the studys lead author and a developmental biologist in the Department of Pathology at the Keck School of Medicine of USC. We want to learn how flight feathers are made so we can better understand nature and learn how biological architecture principles can benefit modern technology.
To gain a comprehensive understanding of the flight feather, Chuong formed a multi-disciplinary international team with Wen Tau Juan, a biophysicist at the Integrative Stem Cell Center, China Medical University in Taiwan. The work involved experts in stem cells, molecular biology, anatomy, physics, bioimaging, engineering, materials science, bioinformatics and animal science. The bird species studied include ostrich, sparrow, eagle, chickens, ducks, swallow, owl, penguin, peacock, heron and hummingbird, among others.
They compared feathers using fossils, stem cells and flight performance characteristics. They focused on the feather shaft, or rachis, that supports the feather much like a mast holds a sail, bearing the stress between wind and wing. They also focused on the vane, the lateral branches astride the shaft that give the feather its shape to flap the air. And they examined how evolution shaped the barbs, ridges and hooks that help a feather hold its form and lock with adjacent feathers like Velcro to form a wing. The goal was to understand how a simple filament appendage on dinosaurs transformed into a three-level branched structure with different functions.
We want to learn how flight feathers are made so we can better understand nature and learn how biological architecture principles can benefit modern technology.
Cheng-Ming Chuong
For birds such as ducks, eagles and sparrows that fly in different modes, the scientists noted significant differences in the feather shaft compared to ground-hugging birds. On the rigid exterior, the shaft cortex was thinner and lightweight, while the interior was filled with porous cells resembling bubble wrap, aligned into bands of various orientations and reinforced with ridges that operate like tiny lateral beams. Together, it forms a light, hollow and buoyant structure to enable flight. Cross-sections of feather shafts of different birds show highly specialized shapes and orientations of the inner core and outer cortex.
The flight feather is made of two highly adaptable architectural modules, light and strong materials that can develop into highly adaptable configurations, Chuong said.
The researchers discovered two different molecular mechanisms guiding feather growth. Cortex thickness was governed by bone morphogenetic proteins, which are molecular signals for tissue growth. The porous feather interior, or medulla, relied upon a different mechanism known as transforming growth factor-beta (TGF-b). Both components originate as stem cells in the birds skin.
By contrast, feathers in flightless birds were simpler, consisting of a dense cortex exterior that is more rigid and sturdy with fewer internal struts and cells found in flying birds. The features were especially pronounced for penguins, which use wings as paddles under the water.
As part of the study, the researchers looked at 100 million-year-old feathers, found embedded in amber in Myanmar. These fossils show early feathers lacked one key feature that modern birds have. Specifically, the researchers report that fossil feathers had barb branches and barbules, which form a feather vane by overlapping, but not hooklets. The hooklets, which act like clasps to turn fluffy feathers into a tight flat plane for high-performance flight, evolved later. The scientists also identified WNT2B, another growth factor, as the agent that controls hooklet formation. These also originated from epidermal stem cells.
Taken together, the findings show how feathered dinosaurs and early birds could form a primitive vane by overlapping barbule plates, although that wasnt aerodynamically fit to carry much load. As more complex composite features occurred in the wing, it got heavier, so feather shafts became stronger yet more lightweight, which led to stiffer feathers and sturdy wings that powered flight to carry birds around the world.
Our findings suggest the evolutionary trends of feather shaft and vane are balanced for the best flight performance of an individual bird and become part of the selective basis of speciation, the study said. The principles of functional architectures we studied here may also stimulate bio-inspired designs and fabrication of future composite materials for architectures of different scales, including wind turbines, artificial tissues, flying drones.
Chuong and Juan are co-leaders of the 31-person team, joined by co-authors Randall B. Widelitz, Shuo Wang, Michael Habib, Ting-Xin Jiang, Zhong-Lai Luo and Ping Wu of the Keck School of Medicine of USC; Wei-Ling Chang, Hao Wu, Yung-Chi Lai, Ming Xing Lei, and Shih-Chieh Hung of the China Medical University Hospital in Taiwan; Ming-You Shie, Jui-Ting Hsu, Heng-Li Huang and Yi-Wen Chen of the China Medical University, Taiwan; Chih-Feng Chen, Ping Chi Tang, Hus Chen Cheng, and Yen-Cheng Lin of the National Chung Hsing University in Taiwan; How-Jen Gu, Yu-Kun Chiu, Tse-Yu Lin, Shun-Min Yang, Tsung-Tse Lee, J.C. Tsai and Yeu-Kuang Hwu of the Institute of Physics, Academia Sinica, Taiwan; Cheng-Te Yao of the Endemic Species Research Institute, Taiwan; Shyh-Jou Shieh of the National Cheng Kung University, Taiwan; Ang Li of the University of Texas, Arlington.
Work at USC was supported by the National Institutes of Health (AR 047364, AR 060306) while team members in Taiwan were supported by grants from their own institutes and the Taiwan government.
More stories about: Biology, Research
Read the original post:
How birds fly: New USC study examines the evolution of flight feathers - USC News
- Politics of Stem Cell Research - May 7th, 2011 [May 7th, 2011]
- Obama Ends Funding Ban for Stem Cell Research - May 8th, 2011 [May 8th, 2011]
- Stem Cell Research: A Father's Fight - May 10th, 2011 [May 10th, 2011]
- Human Embryonic stem cell research - May 11th, 2011 [May 11th, 2011]
- Frost Over The World - Stem Cell Research and Turkey -26 Oct - May 20th, 2011 [May 20th, 2011]
- McCain Favors Embryonic Stem Cell Research - May 20th, 2011 [May 20th, 2011]
- US divided over stem cell research reversal - 09 Mar 09 - May 21st, 2011 [May 21st, 2011]
- The Politics and Promise of Stem Cell Research - May 22nd, 2011 [May 22nd, 2011]
- Inside Story - Obama to end stem cell research ban - March 9 - Part1 - May 30th, 2011 [May 30th, 2011]
- Cardiovascular Therapies: Spotlight on Stem Cell Research - Douglas Boyd - June 3rd, 2011 [June 3rd, 2011]
- The Human Embryo and Embryonic Stem Cell Biology: Spotlight on Stem Cell Research - June 3rd, 2011 [June 3rd, 2011]
- US appeals court lifts stem cell research ban - June 7th, 2011 [June 7th, 2011]
- Trailer for Mapping Stem Cell Research: Terra Incognita - June 9th, 2011 [June 9th, 2011]
- Politics: President Obama on Stem Cell Research - June 10th, 2011 [June 10th, 2011]
- Stem Cell Research Documentary - June 11th, 2011 [June 11th, 2011]
- TEDxSingapore - Susan Lim - Hype and hope of stem cell research - June 13th, 2011 [June 13th, 2011]
- Lou Gehrig's Disease (ALS): Spotlight on Stem Cell Research - Wrapup - June 14th, 2011 [June 14th, 2011]
- The Next Frontier in Stem Cell Research - June 17th, 2011 [June 17th, 2011]
- Robert Klein: Stem Cell Research - June 22nd, 2011 [June 22nd, 2011]
- Fibrocell Stem-Cell Wrinkle Smoother Wins FDA Clearance - June 23rd, 2011 [June 23rd, 2011]
- The Politics of Stem Cell Research - June 23rd, 2011 [June 23rd, 2011]
- A Dose of Reality on Alternative Stem Cell Treatments: What you don't know can hurt you - June 28th, 2011 [June 28th, 2011]
- Governor Tim Pawlenty Discusses Stem Cell Research - June 30th, 2011 [June 30th, 2011]
- The EU and stem cell research - July 5th, 2011 [July 5th, 2011]
- Parkinson's Disease: Spotlight on Stem Cell Research - Jeff Bronstein - July 6th, 2011 [July 6th, 2011]
- Cardiovascular Therapies: Spotlight on Stem Cell Research - Yung-Wei Chi - July 7th, 2011 [July 7th, 2011]
- Spotlight on Cancer Stem Cell Research - July 11th, 2011 [July 11th, 2011]
- A Stem Cell Story - July 12th, 2011 [July 12th, 2011]
- Bishop Blair bars support for Komen breast cancer group - July 13th, 2011 [July 13th, 2011]
- Stem Cell Research In Toronto - July 14th, 2011 [July 14th, 2011]
- Arthritis: Spotlight on Stem Cell Research - Introduction - July 14th, 2011 [July 14th, 2011]
- Huntington's Disease: Spotlight on Stem Cell Research 2007 - Han Keirstead - July 15th, 2011 [July 15th, 2011]
- TMconfUK2011-08 - Stem Cell Research in the UK - Prof Charles Ffrench-Constant - July 16th, 2011 [July 16th, 2011]
- UCSF opens stem cell research building - July 16th, 2011 [July 16th, 2011]
- HIV/AIDS: Spotlight on Stem Cell Research - John Zaia - July 17th, 2011 [July 17th, 2011]
- Deafness: Spotlight on Stem Cell Research - Ebenezer Yamoah - July 22nd, 2011 [July 22nd, 2011]
- Spotlight on Basic Stem Cell Research - Irv Weissman - July 25th, 2011 [July 25th, 2011]
- Diabetes: Spotlight on Stem Cell Research - Peter Butler - July 27th, 2011 [July 27th, 2011]
- Parkinson's Disease: Spotlight on Stem Cell Research - Arnold Kriegstein - July 27th, 2011 [July 27th, 2011]
- HIV/AIDS: Spotlight on Stem Cell Research - Loren Leeds - July 27th, 2011 [July 27th, 2011]
- Alzheimer's Disease: Spotlight on Stem Cell Research - Leeza Gibbons - August 2nd, 2011 [August 2nd, 2011]
- Geron's Embryonic Stem Cell Clinical Trial for Spinal Cord Injury - August 3rd, 2011 [August 3rd, 2011]
- The Skin Gun stem cell research - August 10th, 2011 [August 10th, 2011]
- Deafness: Spotlight on Stem Cell Research - Karen Doyle - August 10th, 2011 [August 10th, 2011]
- Stem Cell Research: Huntington's Disease - August 14th, 2011 [August 14th, 2011]
- Adult and Non-Embryonic Stem Cell Research Conference at Notre Dame - August 20th, 2011 [August 20th, 2011]
- Stemcell Research and Aging - Panel 1 - August 22nd, 2011 [August 22nd, 2011]
- Texans for Stem Cell Research Learn for Life: KXAN Coverage Aired August 16th, 2011 - August 24th, 2011 [August 24th, 2011]
- Stem Cell Research: Macular Degeneration - September 18th, 2011 [September 18th, 2011]
- Brilliant Minds - Stem Cell Research | Tomorrow Today - September 25th, 2011 [September 25th, 2011]
- Ethics of Stem Cell Research (1) - September 29th, 2011 [September 29th, 2011]
- Legal and Public Policy Dimensions of Stem Cell Research - September 29th, 2011 [September 29th, 2011]
- Stem cell symposium - October 2nd, 2011 [October 2nd, 2011]
- StemCONN 2011, The Latest in Stem Cell Research - October 6th, 2011 [October 6th, 2011]
- Arthritis: Spotlight on Stem Cell Research - Mark Genovese - October 7th, 2011 [October 7th, 2011]
- Judy Roberson: Patient advocates drive stem cell scientists - October 8th, 2011 [October 8th, 2011]
- Sam Harris - Stem Cells and Morality - October 8th, 2011 [October 8th, 2011]
- Stem Cell Research, Ethics and Religion - October 9th, 2011 [October 9th, 2011]
- Stem Cells: Fulfilling the Promise - 2011 CIRM Grantee Meeting - October 10th, 2011 [October 10th, 2011]
- The Skin Gun (Stem Cell research to replace burnt off skin. Done in 3 days!) - October 13th, 2011 [October 13th, 2011]
- Alzheimer's Stem Cell Research Patient Advocate Spotlight: The Faces of Neurodegenerative Disease - Video - October 18th, 2011 [October 18th, 2011]
- Life in the Balance: Perspectives on Stem Cell Research - Video - October 18th, 2011 [October 18th, 2011]
- Stem Cell Research Funding Halt - Video - October 19th, 2011 [October 19th, 2011]
- Vatican lending hand in adult stem cell research - Video - October 20th, 2011 [October 20th, 2011]
- First Spinal-Cord Surgery With Stem Cells - Video - October 21st, 2011 [October 21st, 2011]
- Michael J. Fox Embryonic Stem Cell Research - Video - October 22nd, 2011 [October 22nd, 2011]
- stem cell research - Video - October 22nd, 2011 [October 22nd, 2011]
- Gayle Atteberry - Cloning - November 5th, 2011 [November 5th, 2011]
- It Takes Nerve: UC Irvine - Sue - November 6th, 2011 [November 6th, 2011]
- Embryonic Stem Cell Research - Video - November 9th, 2011 [November 9th, 2011]
- Adult Stem Cell Research Far Ahead of Embryonic - Video - November 10th, 2011 [November 10th, 2011]
- Is stem cell research a growing concern .flv - Video - November 10th, 2011 [November 10th, 2011]
- Forbes Discusses Stem Cell Research - Video - November 14th, 2011 [November 14th, 2011]
- Stem Cell Research Presentation - Video - November 16th, 2011 [November 16th, 2011]
- Benedict XVI: No embryonic stem cell research - Video - November 28th, 2011 [November 28th, 2011]
- Batten Disease: Spotlight on Stem Cell Research - A Father's Story - Video - November 30th, 2011 [November 30th, 2011]
- CIS 111 Digital Media Project - Stem Cell Research - Video - December 13th, 2011 [December 13th, 2011]
- Regenerative Medicine and Applications of Stem Cell Research - Video - December 20th, 2011 [December 20th, 2011]
- Stem Cell Research Today: Larry Goldstein - CIRM Science Writer's Seminar - Video - December 22nd, 2011 [December 22nd, 2011]
- CIRM Bridges Award: Building California's Stem Cell Research Workforce - Video - December 22nd, 2011 [December 22nd, 2011]