HEYOKA MAGAZINE. ROBERT CHAMBERS

Scientists have discovered glycolaldehyde, a molecular cousin to table sugar, in an interstellar molecular cloud"The discovery of this sugar molecule in a cloud from which new stars are forming means it is increasingly likely that the chemical precursors to life are formed in such clouds long before planets develop around the stars," said Jan M. Hollis of the NASA Goddard Space Flight Center in Greenbelt, MD.

The National Radio Astronomy Observatory's 12 Meter Telescope was used by Jan Hollis (NASA/Goddard),

Frank J. Lovas (University of Illinois) and Philip R. Jewell (NRAO/Green Bank) to detect the sugar molecule glycolaldehyde in an interstellar molecular cloud. Credit: NRAO.

"This discovery may be an important key to understanding the formation of life on the early Earth," agreed Philip Jewell of the National Radio Astronomy Observatory (NRAO). Conditions in interstellar clouds may, in some cases, mimic the conditions on the early Earth, so studying the chemistry of interstellar clouds may help scientists understand how bio-molecules formed early in our planet's history. In addition, some scientists have suggested that Earth could have been "seeded" with complex molecules by passing comets, made of material from the interstellar cloud that condensed to form the Solar System.

Glycolaldehyde, an 8-atom molecule composed of carbon, oxygen and hydrogen, can combine with other molecules to form the more-complex sugars Ribose and Glucose. Ribose is a building block of nucleic acids such as RNA and DNA, which carry the genetic code of living organisms. Glucose is the sugar found in fruits. Glycolaldehyde contains exactly the same atoms, though

in a different molecular structure, as

methyl formate and acetic acid, both of which were detected previously in interstellar clouds. Glycolaldehyde is a simpler molecular cousin to table sugar, the scientists say.

Above: Glycolaldehyde, the simplest sugar, compared to more complex sugar forms that occur naturally (i.e., the D-sugars). Glycolaldehyde is the only member of the sugar family yet detected in interstellar clouds. Note that the structure of glycolaldehyde is contained in both Ribose and Glucose. Ribose sugars make up the backbone of the ribonucleic acid (RNA) molecule which is involved in protein synthesis in living cells. Glucose, the most common sugar, occurs in plant saps and fruits. Credit: NRAO.

The sugar molecule was detected in a large cloud of gas and dust some 26,000 light-years away, near the center of our Galaxy. Such clouds, often many light-years across, are the material from which new stars are formed. Though very rarefied by Earth standards, these interstellar clouds are the sites of complex chemical reactions that occur over hundreds of thousands or millions of years. So far, about 120 different molecules have been discovered in these clouds. Most of these molecules contain a small number of atoms, and only a few molecules with eight or more atoms have been found in interstellar clouds.

Right: Jan M. Hollis of the NASA Goddard Space Flight Center in Greenbelt, MD. Credit: NASA/GSFC

"Finding glycolaldehyde in one of these interstellar clouds means that such molecules can be formed even in very rarefied conditions," added Hollis. "We don't yet understand how it could be formed there. A combination of more astronomical observations and theoretical chemistry work will be required to resolve the mystery of how this molecule is formed in space."

"We hope this discovery inspires renewed efforts to find even more kinds of molecules, so that, with a better idea of the total picture, we may be able to deduce the details of the prebiotic chemistry taking place in interstellar clouds," Hollis said.

The discovery was made by detecting faint radio emission from the sugar molecules in the interstellar cloud. Molecules rotate end-for-end, and as they change from one rotational energy state to another, they emit radio waves at precise frequencies. The "family" of radio frequencies emitted by a particular molecule forms a unique "fingerprint" that scientists can use to identify that molecule. The scientists identified glycolaldehyde by detecting six frequencies of radio emission in what is termed the millimeter-wavelength region of the electromagnetic spectrum -- a region between more-familiar microwaves and infrared radiation.

Above: The giant molecular cloud, known as Sagittarius B2 (North), as seen by the NSF's Very Large Array (VLA) radio telescope in New Mexico. This is the cloud in which scientists using the 12 Meter Telescope detected the simple sugar molecule glycolaldehyde. This VLA image shows hydrogen gas in a region nearly 3 light-years across. The 12 Meter Telescope studied this region at much shorter wavelengths, which revealed the evidence of sugar molecules. CREDIT: R. Gaume, M. Claussen, C. De Pree, W.M. Goss, D. Mehringer, NRAO/AUI/NSF.

The NRAO 12 Meter Telescope used to detect the sugar molecule has been a pioneer instrument in the detection of molecules in space. Built in 1967, it made the first detections of dozens of the molecules now known to exist in space, including the important first discovery of carbon monoxide, now widely used by astronomers as a signpost showing regions where stars are being formed. It is scheduled to be closed at the end of July, in preparation for the Atacama Large Millimeter Array, an advanced system of 64 radio-telescope antennas in northern Chile now being developed by an international partnership.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

Clue To Obesity

The idea that obese people eat too much because they find food more palatable than lean people do has gained support from a new brain-imaging study at the U.S.Department of Energy's Brookhaven National Laboratory. The study reveals that the parts of the brain responsible for sensation in the mouth, lips, and tongue are more active in obese people than in normal-weight control subjects.

"This enhanced activity in brain regions involved with sensory processing of food could make obese people more sensitive to the rewarding properties of food, and could be one of the reasons they overeat," said Brookhaven physician Gene-Jack Wang, lead author of the study.

Wang acknowledges that obesity is a complex disease with many contributing factors, including genetics, abnormal eating behavior, lack of exercise, and cultural influences, as well as cerebral mechanisms, which are not yet fully understood. In a recent study, he and his team found that obese people have fewer brain receptors for dopamine, a neurotransmitter that helps produce feelings of satisfaction and pleasure, implying that obese people may eat to stimulate their underserved reward circuits, just as addicts do by taking drugs.

In that study, overall brain metabolism did not differ between obese and normal-weight controls. But because the sensory appeal of food can be so important in triggering the urge to eat, Wang and his team wondered whether obese people might have enhanced metabolic activity in specific brain regions, particularly those involved in the sensory processing of food.

To measure regional brain metabolism, the scientists used positron emission tomography (PET) after injecting volunteers (10 severely obese and 20 normal controls) with a radioactively labeled form of glucose, the brain's metabolic fuel. Known as FDG, this radiotracer (invented at Brookhaven) acts like glucose in the brain, concentrating in regions where metabolic activity is highest. The PET scanner picks up the radioactive signal to reveal where the FDG is located.

The scientists used a computer program to average the PET data from the subjects within each group, and then compared the obese subjects' average with the normal subjects' result. The program produced three-dimensional images highlighting areas where the obese group had higher metabolic activity than the normal-weight group.

The scientists then superimposed these images onto a magnetic resonance image (MRI) of the whole brain, as well as a diagram of the brain's somatosensory cortex, known as a homunculus. A homunculus graphically illustrates the relative number of sensory nerves innervating various parts of the body as well as where the input from these nerves is received on the somatosensory cortex.

The overlapping images revealed "hot spots" - indicating obese subjects' higher metabolic activity - in the regions of the parietal cortex where somatosensory input from the mouth, lips, and tongue is received. This is also an area involved with taste perception.

"The enhanced activation of these parietal regions in obese subjects is consistent with an enhanced sensitivity to food palatability, which is likely to increase the rewarding properties of food," Wang said.

Taken together with the earlier results on deficient reward circuits, this enhanced sensitivity could account for the powerful appeal and significance that food has for obese individuals.

The findings also suggest that pharmacological treatments known to decrease palatability might be useful along with behavioral therapies in reducing food intake in obese subjects.

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