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How life might evolve with “exotic” biochemistry and solvents

September 19, 2009 By admin Leave a Comment

London, September 18 (ANI): Scientists at a new interdisciplinary research group in Austria are working to uncover how life might evolve with “exotic” biochemistry and solvents, such as sulfuric acid instead of water.

The research group for Alternative Solvents as a Basis for Life Supporting Zones in (Exo-) Planetary Systems was established by the University of Vienna.

Traditionally, planets that might sustain life are looked for in the ‘habitable zone’, the region around a star in which Earth-like planets with carbon dioxide, water vapor and nitrogen atmospheres could maintain liquid water on their surfaces.

Consequently, scientists have been looking for biomarkers produced by extraterrestrial life with metabolisms resembling the terrestrial ones, where water is used as a solvent and the building blocks of life, amino acids, are based on carbon and oxygen.

However, these may not be the only conditions under which life could evolve.

“It is time to make a radical change in our present geocentric mindset for life as we know it on Earth,” said scientist Johannes Leitner.

“Even though this is the only kind of life we know, it cannot be ruled out that life forms have evolved somewhere that neither rely on water nor on a carbon and oxygen based metabolism,” he added.

One requirement for a life-supporting solvent is that it remains liquid over a large temperature range.

Water is liquid between 0 degree Celsius and 100 degrees C, but other solvents exist which are liquid over more than 200 degrees C.

Such a solvent would allow an ocean on a planet closer to the central star.

The reverse scenario is also possible. A liquid ocean of ammonia could exist much further from a star.

Furthermore, sulfuric acid can be found within the cloud layers of Venus and it is now known that lakes of methane/ethane cover parts of the surface of the Saturnian satellite Titan.

Consequently, the discussion on potential life and the best strategies for its detection is ongoing and not only limited to exoplanets and habitable zones.

The newly established research group at the University of Vienna, together with international collaborators, will investigate the properties of a range of solvents other than water, including their abundance in space, thermal and biochemical characteristics as well as their ability to support the origin and evolution of life supporting metabolisms. (ANI)

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Higher metabolism doesn’t mean shorter lifespan: Study

March 10, 2009 By admin Leave a Comment

Washington, Mar 10(ANI): A new study, led by Lobke Vaanholt (University of Groningen, The Netherlands), has cast significant doubt on the theory that a higher metabolism means a shorter lifespan.

In the study, the researchers found that mice with increased metabolism live just as long as those with slower metabolic rates.

The theory that fast-living animals die young, known as the rate-of-living theory, was first proposed in the 1920s.

The faster you expend energy, the faster you age, and the sooner you die. It remained a prominent theory of aging until recently, when comparisons across broad animal groups cast doubt on it.

For instance, birds have significantly higher metabolisms than mammals of similar size, yet the birds live much longer.

Vaanholt’s study was designed to test the rate-of-living theory among individuals of one species-mice.

For the study, Vaanholt and her team followed two groups of mice through their entire lives.

One group’s environment was kept at 71 degrees Fahrenheit (22 degrees Celsius), and the other group’s at 50 degrees Fahrenheit (10 degrees Celsius).

The colder group had to expend more energy to maintain body temperature, and according to the rate-of-living theory, should therefore die sooner than the warm group.

However, that’s not what happened.

“Despite a 48 percent increase in overall daily energy expenditure and a 64 percent increase in mass-specific energy expenditure throughout adult life, mice in the cold lived just as long on average as mice in warm temperatures. These results strengthen existing doubts about the rate-or-living theory,” the authors said.

The study has been published in the journal Physiological and Biochemical Zoology. (ANI)

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Why some people become fat and others don’t

January 19, 2009 By Rajesh Leave a Comment

London, Jan 19 (ANI): Researchers at Imperial College London, the French National Research Institute CNRS and other international institutions have discovered three new genetic variations that increase the risk of obesity, giving new insight into the reasons why some people become fat and others don’t.

They suggest that if each acted independently, these variants could be responsible for up to 50 percent of cases of severe obesity.

According to researchers, the new findings should ultimately provide the tools to predict which young children are at risk of becoming obese.

For the study, the researchers looked at the genetic makeup of obese children under six and morbidly obese adults, most of whom had been obese since childhood or adolescence, and compared this with age matched people of normal weight.

The researchers discovered three previously unidentified genetic variations that increase the risk of severe obesity significantly.

The gene variant most strongly linked to childhood obesity and adult morbid obesity in the study is located near the PTER gene, the function of which is not known.

This variant is estimated to account for up to a third of all childhood obesity, and a fifth of all cases of adult obesity.

The second variant linked to child and adult obesity is found in the NPC1 gene.

Previous studies in mice have suggested that this gene has a role in controlling appetite, as mice with a non-functioning NPC1 gene suffer late-onset weight loss and have poor food intake.

This gene variant accounts for around 10 per cent of all childhood obesity and about 14 per cent of adult morbid obesity cases.

The final variant is found near the MAF gene, which controls the production of the hormones insulin and glucagon, as well as chains of amino acids called glucagon-like peptides.

These hormones and peptides are known to play key roles in people’s metabolisms by metabolising glucose and carbohydrates in the body. Also, glucagon and glucagon-like peptides appear to have a strong effect on people’s ability to feel ‘full’ or satiated after eating.

This variant accounts for about 6 per cent of early-onset obesity in children, and 16 per cent of adult morbid obesity.

The researchers reached their conclusions by conducting a genome-wide association study of 1,380 Europeans with early-onset childhood obesity and adult morbid obesity, and 1,416 age-matched normal weight controls.

The study revealed 38 genetic markers with a strong association to a higher than normal body mass index, which the researchers evaluated in 14,186 Europeans, identifying three mutations that are significantly linked to obesity.

The study is published in the journal Nature Genetics. (ANI)

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