Researchers find dinosaur clues in fat

Apr 23, 2008

A 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.

Source: New York Medical College

Explore further: Giant anteaters kill two hunters in Brazil

add to favorites email to friend print save as pdf

Related Stories

Burmese pythons prove elusive prey in Florida challenge

Feb 27, 2013

Strapped to Billy Bullard's hip was a machete he'd bought at a yard sale. In his fist were 4-foot-long metal snake tongs. Attached to the tongs was a high-resolution waterproof camera he called a "snake-cam."

'Smart' potty or dumb idea? Wacky gadgets at CES

Jan 09, 2013

From the iPotty for toddlers to the 1,600-pound (725-kilogram) mechanical spider and the host of glitch-ridden "smart" TVs, the International CES show is a forum for gadget makers to take big—and bizarre—chances.

Recommended for you

Giant anteaters kill two hunters in Brazil

2 hours ago

Giant anteaters in Brazil have killed two hunters in separate incidents, raising concerns about the animals' loss of habitat and the growing risk of dangerous encounters with people, researchers said.

Rising temperatures can be hard on dogs

20 hours ago

The "dog days of summer" are here, but don't let the phrase fool you. This hot time of year can be dangerous for your pup, says a Kansas State University veterinarian.

User comments : 0