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Medical College researchers find dinosaur clues in fat
April 24, 2008A team of researchers at New York Medical College has discovered why birds, unlike mammals, lack a tissue that is specialized to generate heat. A paper published April 21, 2008 in the online peer-reviewed journal BMC Biology contains the surprising implication that the same lack of heat-generating tissue may have contributed to the extinction of dinosaurs.
The paper, "The brown adipocyte differentiation pathway in birds: an evolutionary road not taken," was written by Stuart A. Newman, Ph.D., professor of cell biology and anatomy, Nadejda Mezentseva, a Ph.D. candidate at New York Medical College, and Jaliya Kumaratilake, Ph.D., University of Adelaide, Australia.
Humans, like all mammals, have two kinds of adipose tissue, white fat and brown fat. White fat is used for storing energy-rich fuels, while brown fat generates heat. Hibernating bears have a lot of brown fat, as do human infants, who have much more than adults, relative to their body size. Infants' brown fat protects them from hypothermia. Clinicians would like to find ways of making adult white fat behave more like brown fat so that we could burn, rather than store, energy.
While most mammals have a key gene called UCP1, which is responsible for the heat-generation function of brown fat, birds do not. The researchers found they could induce a specific type of stem cell in chicken embryos to produce differentiated cells that are structured and behave like brown fat. These chicken cells can even activate a UCP1 gene if presented with one from a mouse.
The ability to produce brown fat evolved in a common ancestor of birds and mammals, but the ability to generate heat was lost in the group that gave rise to birds and lizards after it separated from the mammalian lineage (the researchers found the lizard genome similarly lacks a UCP1 gene). This strongly implies that dinosaurs, which diverged from birds even later than lizards, also lacked brown fat.
New York Medical College
While most mammals have a key gene called UCP1, which is responsible for the heat-generation function of brown fat, birds do not. The researchers found they could induce a specific type of stem cell in chicken embryos to produce differentiated cells that are structured and behave like brown fat. These chicken cells can even activate a UCP1 gene if presented with one from a mouse.
The ability to produce brown fat evolved in a common ancestor of birds and mammals, but the ability to generate heat was lost in the group that gave rise to birds and lizards after it separated from the mammalian lineage (the researchers found the lizard genome similarly lacks a UCP1 gene). This strongly implies that dinosaurs, which diverged from birds even later than lizards, also lacked brown fat.
New York Medical College
Mammal Current Events and Mammal News RSSFunny, you don't look related
When Charles Darwin visited the Falkland Islands during the voyage of the Beagle in 1835, he saw a wolf-like species, wrote about it in his diaries and correctly commented that it was being hunted in such large numbers that it would soon become extinct.
Chinese and American paleontologists discover a new Mesozoic mammal
An international team of paleontologists has discovered a new species of mammal that lived 123 million years ago in what is now the Liaoning Province in northeastern China.
Early hominid first walked on two legs in the woods
Among the many surprises associated with the discovery of the oldest known, nearly complete skeleton of a hominid is the finding that this species took its first steps toward bipedalism not on the open, grassy savanna, as generations of scientists - going back to Charles Darwin - hypothesized, but in a wooded landscape.
CU-Boulder team identifies DNA barcodes to help track illegal trading of wildlife products
Researchers from several institutions including the University of Colorado at Boulder have sequenced DNA "barcodes" for as many as 25 hunted wildlife species, providing information that can be used to better monitor the elusive trade of wildlife products, or bushmeat.
Sheep that shed light on personality differences
The team led by Denis Reale, a professor in the Department of Biological Sciences at UQAM and Canada Research Chair in Behavioural Ecology, recently completed a study showing the link between personality, survival and reproductive success in male bighorn sheep.
Mice living in sandy hills quickly evolved lighter coloration
In a vivid illustration of natural selection at work, scientists at Harvard University have found that deer mice living in Nebraska's Sand Hills quickly evolved lighter coloration after glaciers deposited sand dunes atop what had been much darker soil. The work is described this week in the journal Science.
Hundreds of New Species Discovered in Fragile Eastern Himalayas
Over 350 new species including the world's smallest deer, a "flying frog" and a 100 million-year old gecko have been discovered in the Eastern Himalayas, a biological treasure trove now threatened by climate change.
Climate caused biodiversity booms and busts in ancient plants and mammals
A period of global warming from 53 million to 47 million years ago strongly influenced plants and animals, spurring a biodiversity boom in western North America, researchers from three research museums report in a paper published online this week in the Proceedings of the National Academy of Sciences.
Naming evolution's winners and losers
Mammals and many species of birds and fish are among evolution's "winners," while crocodiles, alligators and a reptile cousin of snakes known as the tuatara are among the losers, according to new research by UCLA scientists and colleagues.
Bizarre walking bat has ancient heritage
A bizarre New Zealand bat that is as much at home walking four-legged on the ground as winging through the air had an Australian ancestor 20 million years ago with the same rare ability, a new study has found.
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