The discovery of a possible hibernation hormone in the brain may unlock the mystery behind the dormant state, researchers reported in Cell. Hibernation allows animals from bears to rodents to survive unscathed–in a state of suspended animation–under the harshest of winter conditions.

If the findings in chipmunks are confirmed, the hormone would represent the first essential brain signal governing the seasonal adaptation, according to the researchers.

As hibernation factors endow animals with an incredible ability to cope under otherwise lethal conditions–ratcheting down their metabolic rate to survive on limited energy reserves and withstanding extreme cardiovascular and oxygen stresses–the candidate hormone might also pave the way toward clinical therapies that lend humans the same kind of protection, they added.

The researchers earlier found that concentrations of “hibernation-specific protein” complex (HPc) decline in the blood of hibernating chipmunks. The team now reports evidence that the level of HPc in the brain increases at the onset of hibernation independently of changes in body temperature. Moreover, treatments that block HP activity in the animals’ brains cuts hibernation short.

“One of the most curious biological phenomena in mammals is their ability to hibernate circannually, which allows them to survive unusually low body temperatures at or near freezing,” said study author Noriaki Kondo of Mitsubishi Kagaku Institute of Life Sciences in Japan. Scientists have attempted for decades to identify substances responsible for hibernation in the blood and organs of hibernating animals but have met with little success, the researchers said.

“Although the functions of HP remain to be clarified, the current observations lead us to propose the involvement of the protein complex in the regulation of energy metabolism and/or biological defenses during hibernation–crucial events for adapting to the severe physiological state,” Kondo said.

In the current study, the researchers first demonstrated that hibernation in chipmunks is strictly controlled by an individual’s internal circannual rhythm even under conditions of constant cold. In 20 hibernators examined throughout their lives, concentrations of HPc in the blood started to decrease prior to hibernation and remained low throughout the inactive state. Hibernation ended after blood HPc levels rose.

Further study revealed an inverse relationship between HPc levels in the blood and brain. While HPc levels dipped in blood, the putative hormone rose dramatically in cerebral spinal fluid, they reported. Likewise, HPc levels decreased abruptly in spinal fluid when hibernation terminated.

The researchers also found that blocking the activity of one of the HP complex proteins in the brain with antibody greatly decreased the hibernation time during which the chipmunks maintained a lowered body temperature, suggesting its critical role in the brain’s capacity for dormancy.

The researchers propose that HPc in the blood is actively transported into the spinal fluid in response to the animals’ natural rhythm. The hibernation complex might also play a role in the seasonal behavior changes of animal species that do not hibernate, the researchers suggested.

For example, the complex could moderate physiological events such as reproduction in seasonally breeding mammals and migration in birds, they said. Even humans can maintain seasonal rhythms as exhibited by seasonal affective disorder, a recurrent depression characterized by increased sleep, overeating, and weight gain–behaviors similar to those seen in hibernators, Kondo noted.

“Hibernation is an extreme response to a seasonal environment, yet we knew almost nothing about how it is timed, nor how vital cellular functions are sustained in the face of plummeting body temperature,” wrote Michael Hastings in a preview. The researchers now “identify a liver-derived protein complex as an essential coordinator of this adaptation to the depredations of winter.”

“The finding has more than passing biological interest because understanding how tissues cope with the cardiovascular and oxidative stresses associated with hibernation or torpor may have direct clinical relevance,” he added.

For example, he wrote, such a protective program might be exploited in transplant and vascular surgery. Scientists have suggested that hibernation therapy might effectively preserve donor organs for weeks or months.

Hibernation has also been found to protect animals from a wide range of potential threats, from muscle disuse to cancer, the study authors said. Therefore, hibernation therapy might confer protective effects in other clinical arenas as well.

The new findings could lead to “potential pharmacological applications in humans to the prevention of lethal diseases, such as hypothermia, ischemia, muscle atrophy, bacterial infection, and tumorigenesis, which has been observed during hibernation in hibernators,” the researchers said.

“These studies may further stimulate the exploration of new techniques for cryosurgery of the heart and brain, as well as the development of hypothermia treatment that is effective for preventing brain ischemic damage.” In cryosurgery, physicians use extreme cold to destroy abnormal tissue, such as cancerous tumors.

Noriaki Kondo of Kanagawa Academy of Science and Technology (KAST) in Machida, Tokyo; Tsuneo Sekijima of Kanagawa Academy of Science and Technology (KAST) in Machida, Tokyo and Niigata University in Niigata, Japan; Jun Kondo of Kanagawa Academy of Science and Technology (KAST) in Machida, Tokyo and Mitsubishi-Tokyo Pharmaceuticals Inc. Yokohama Research Center, Kanagawa, Japan; Nobuhiko Takamatsu of Kanagawa Academy of Science and Technology (KAST) in Machida, Tokyo and Kitasato University in Kanagawa, Japan; Kazuo Tohya of Kansai College of Oriental Medicine in Osaka, Japan; and Takashi Ohtsu of Kanagawa Academy of Science and Technology (KAST) in Machida, Tokyo and Kanagawa Cancer Center Research Institute in Yokohama, Japan. This work was supported, in part, by the National Space Development Agency of Japan.

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An international team of astronomers has discovered within the heart of a nearby spiral galaxy a quasar whose light spectrum indicates that it is billions of light years away. The finding poses a cosmic puzzle: How could a galaxy 300 million light years away contain a stellar object several billion light years away?

The team’s findings, which were presented today in San Diego at the January meeting of the American Astronomical Society and which will appear in the February 10 issue of the Astrophysical Journal, raise a fundamental problem for astronomers who had long assumed that the “high redshifts” in the light spectra of quasars meant these objects were among the fastest receding objects in the universe and, therefore, billions of light years away.

“Most people have wanted to argue that quasars are right at the edge of the universe,” said Geoffrey Burbidge, a professor of physics and astronomer at the University of California at San Diego’s Center for Astrophysics and Space Sciences and a member of the team. “But too many of them are being found closely associated with nearby, active galaxies for this to be accidental. If this quasar is physically associated with this galaxy, it must be close by.”

Astronomers generally estimate the distances to stellar objects by the speed with which they are receding from the earth. That recession velocity is calculated by measuring the amount the star’s light spectra is shifted to the lower frequency, or red end, of the light spectrum. This physical phenomenon, known as the Doppler Effect, can be experienced by someone standing near train tracks when the whistle or engine sounds from a moving train becomes lower in pitch, or sound frequency, as the train travels past.

Astronomers have used redshifts and the known brightness of stars as fundamental yardsticks to measure the distances to stars and galaxies. However, Burbidge said they have been unable to account for the growing number of quasi-stellar objects, or quasars—intense concentrations of energy believed to be produced by the swirling gas and dust surrounding massive black holes—with high redshifts that have been closely associated with nearby galaxies.

“If it weren’t for this redshift dilemma, astronomers would have thought quasars originated from these galaxies or were fired out from them like bullets or cannon balls,” he added.

The discovery reported by the team of astronomers, which includes his spouse, E. Margaret Burbidge, another noted astronomer and professor of physics at UCSD, is especially significant because it is the most extreme example of a quasar with a very large redshift in a nearby galaxy.

“No one has found a quasar with such a high redshift, with a redshift of 2.11, so close to the center of an active galaxy,” said Geoffrey Burbidge.

Margaret Burbidge, who reported the team’s finding at the meeting, said the quasar was first detected by the ROSAT X-ray satellite operated by the Max-Planck Institute for Astrophysics in Garching, Germany and found to be closely associated with the nucleus of the spiral galaxy NGC 7319. That galaxy is unusual because it lies in a group of interacting galaxies called Stephan’s Quintet.

Using a three-meter telescope operated by the University of California at Lick Observatory in the mountains above San Jose and the university’s 10-meter Keck I telescope on Mauna Kea in Hawaii, she and her team measured the redshifts of the spiral galaxy and quasar and found that the quasar appears to be interacting with the interstellar gas within the galaxy.

Because quasars and black holes are generally found within the most energetic parts of galaxies, their centers, the astronomers are further persuaded that this particular quasar resides within this spiral galaxy. Geoffrey Burbidge added that the fact that the quasar is so close to the center of this galaxy, only 8 arc seconds from the nucleus, and does not appear to be shrouded in any way by interstellar gas make it highly unlikely that the quasar lies far behind the galaxy, its light shining through the galaxy near its center by “an accident of projection.”

“If this quasar is close by, its redshift cannot be due to the expansion of the universe,” he adds. “If this is the case, this discovery casts doubt on the whole idea that quasars are very far away and can be used to do cosmology.”

Other members of the team, besides Geoffrey and Margaret Burbidge, included Vesa Junkkarinen, a research physicist at UCSD; Pasquale Galianni of the University of Lecce in Italy; and Halton Arp and Stefano Zibetti of the Max-Planck Institute for Astrophysics in Garching, Germany.

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Astronomers have at last found definitive evidence that the universe’s first dust – the celestial stuff that seeded future generations of stars and planets – was forged in the explosions of massive stars.

The findings, made with NASA’s Spitzer Space Telescope, are the most significant clue yet in the longstanding mystery of where the dust in our very young universe came from. Scientists had suspected that exploding stars, or supernovae, were the primary source, but nobody had been able to demonstrate that they can create copious amounts of dust – until now. Spitzer’s sensitive infrared detectors have found 10,000 Earth masses worth of dust in the blown-out remains of the well-known supernova remnant Cassiopeia A.

“Now we can say unambiguously that dust – and lots of it – was formed in the ejecta of the Cassiopeia A explosion. This finding was possible because Cassiopeia A is in our own galaxy, where it is close enough to study in detail,” said Jeonghee Rho of NASA’s Spitzer Science Center at the California Institute of Technology in Pasadena. Rho is the lead author of a new report about the discovery appearing in the Jan. 20 issue of the Astrophysical Journal.

Space dust is everywhere in the cosmos, in our own neck of the universe and all the way back billions of light-years away in our infant universe. Developing stars need dust to cool down enough to collapse and ignite, while planets and living creatures consist of the powdery substance. In our nearby universe, dust is pumped out by dying stars like our sun. But back when the universe was young, sun-like stars hadn’t been around long enough to die and leave dust.

That’s where supernovae come in. These violent explosions occur when the most massive stars in the universe die. Because massive stars don’t live very long, theorists reasoned that the very first exploding massive stars could be the suppliers of the unaccounted-for dust. These first stars, called Population III, are the only stars that formed without any dust.

Other objects in addition to supernovae might also contribute to the universe’s first dust. Spitzer recently found evidence that highly energetic black holes, called quasars, could, together with supernovae, manufacture some dust in their winds.

Rho and her colleagues analyzed the Cassopeia A supernova remnant, located about 11,000 light-years away. Though this remnant is not from the early universe, its proximity to us makes it easier to address the question of whether supernovae have the ability to synthesize significant amounts of dust. The astronomers analyzed the infrared light coming from Cassiopeia A using Spitzer’s infrared spectrograph, which spreads light apart to reveal the signatures of different elements and molecules. “Because Spitzer is extremely sensitive to dust, we were able to make high-resolution maps of dust in the entire structure,” said Rho.

The map reveals the quantity, location and composition of the supernova remnant’s dust, which includes proto-silicates, silicon dioxide, iron oxide, pyroxene, carbon, aluminium oxide and other compounds. One of the first things the astronomers noticed was that the dust matches up perfectly with the gas, or ejecta, known to have been expelled in the explosion. This is the smoking gun indicating the dust was freshly made in the ejecta from the stellar blast. “Dust forms a few to several hundred days after these energetic explosions, when the temperature of gas in the ejecta cools down,” said Takashi Kozasa, a co-author at the Hokkaido University in Japan.

The team was surprised to find freshly-made dust deeper inside the remnant as well. This cooler dust, mixed in with gas referred to as the unshocked ejecta, had never been seen before.

All the dust around the remnant, both warm and cold, adds up to about three percent of the mass of the sun, or 10,000 Earths. This is just enough to explain where a large fraction, but not all, of the universe’s early dust came from. “Perhaps at least some of the unexplained portion is much colder dust, which could be observed with upcoming telescopes, such as Herschel,” said Haley Gomez, a co-author at University of Wales, Cardiff. The Herschel Space Observatory, scheduled to launch in 2008, is a European Space Agency mission with significant NASA participation.

Rho also said that more studies of other supernovae from near to far are needed to put this issue to rest. She notes that the rate at which dust is destroyed – a factor in determining how much dust is needed to explain the dusty early universe – is still poorly understood.

The principal investigator of the research program, and a co-author of the paper, is Lawrence Rudnick of the University of Minnesota, Twin Cities. Other co-authors include W.T. Reach of the Spitzer Science Center; J. D. Smith of the Steward Observatory, Tucson, Ariz.; T. Delaney of the Massachusetts Institute of Technology, Cambridge; J.A. Ennis of the University of Minnesota; and A. Tappe of the Spitzer Science Center and the Harvard Smithsonian Center for Astrophysics, Cambridge, Mass.

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