Science Sunday: Arctic Ice, Mars Water, Space Aliens

How low can it go?
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Arctic sea ice reached its minimum extent for 2007 on September 16, and was the lowest since satellite record-keeping began almost 30 years ago, according to the University of Colorado-Boulder’s National  Snow and Ice Data Center.

Compared to the long-term minimum average, the extent was lower by about one million square miles, an  area about the size of Alaska and Texas combined.

“The amount of ice loss this year absolutely stunned us because it didn’t just beat all previous records, it completely shattered them,” said CU-Boulder senior scientist Mark Serreze of NSIDC.

“Scientists blame the declining Arctic sea ice on rising concentrations of greenhouse gases that have elevated temperatures from 2 degrees F to 7 degrees F across the arctic and strong natural variability in Arctic sea ice,” said the researchers in a CU news release.

“The CU-Boulder research group said determining the annual minimum sea ice is difficult until the melt season has decisively ended. But the team has recorded five days of little change, and even slight gains in Arctic sea ice extent this September, so reaching a lower minimum for 2007 seems unlikely.”

Alien space monsters

Bacterial pathogens grown in space showed substantial differences in molecular genetic and phenotypic responses compared with the same bacteria grown in identical conditions on earth.

A large group of researchers that included Louis Stodieck of the University of Colorado’s Bioserve group found that 167 gene transcripts and 73 proteins changed expression in the pathogen Salmonella typhimurium that was grown on board the space shuttle, compared with an earth-grown sample of the bacteria. The changes in the genetics were in the direction of a more virulent strain.

The study discovered that an important regulatory protein, Hfq, may be a key molecule responsible for the increased virulence due to space flight. “Hfq is a protein that binds to and regulates a number of regulatory RNAs, which in turn, control gene expression,” said Arizona State University Prof. Cheryl Nickerson, one of the leaders of the study. “Our studies suggest that there may be a role for these regulatory RNAs in the cellular response to the physical and mechanical forces found in space flight, which are relevant to conditions that cells encounter here on Earth during the normal course of their life cycles.”

These results have important implications for human health since Salmonella (and other gut-related bacterial pathogens) are a leading cause of food-borne illness and infectious disease, especially in the developing world. Nickerson’s group further highlights Hfq as a potential therapeutic target, since no vaccine currently exists for Salmonella food-borne infections in humans. In addition, the space flight studies may shed new light on why Salmonella has become increasingly resistant to antibiotic treatment, said an ASU release.

Water on Mars

Back when people first looked at Mars in telescopes, they thought they saw canals on the planet, which they took to mean it was inhabited. The canals were a mistake, it turns out, but the hope of finding evidence for some form of life on Mars lives on, primarily because it’s believed the planet once had water.

A large group of researchers that include a couple of CU scientists have looked at photos and data form the Mars Reconnaissance Orbiter, finding evidence of “fluvial modification of geologically recent mid-latitude gullies.” That is, maybe the action of water.

They could not, however, verify the speculation that Mars was once home to large ancient oceans.

Mars has braided channels and a “gully morphologies … similar to water-carved features on Earth.

“We are not aware of common terrestrial processes besides running water that could explain all of these observations,” the scientists conclude in a paper published in the September 21 issue of the journal Science.

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Many gullies on Mars include braided channels, terraces and other features that are similar to water-carved features on Earth. Color (here and in other figures) is constructed from red and blue-green band passes and exaggerated as compared with natural color. Downslope direction is toward the bottom of (A) and the lower left of (B) and (C). These images are from the Mars Reconnaissance Orbiter