Editor’s note: Science Scan is a roundup of recently published biotechnology-relevant research.
Hundreds of feet below the Beaverhead Mountains in Idaho, a team of geochemists and microbiologists has discovered a colony of unique, heat-loving microorganisms that may help answer the question of how life could survive on Mars. Their report appears in Nature, dated Jan. 17, 2002, under the title: “A hydrogen-based subsurface microbial community dominated by methanogens.”
Its senior author is Derek Lovley, head of microbiology at the University of Massachusetts in Amherst. The paper’s first author is biochemist/hydrologist Francis Chapelle of the U.S. Geological Survey in Columbia, S.C.
“There’s a controversy that’s been going on back to the beginning of the 20th century,” Chapelle told BioWorld Today, “about how life could have arisen on Earth or Mars or other extraterrestrial bodies. One hypothesis said that life or at least the first metabolism could have begun by coupling the oxidation of molecular hydrogen to inorganic carbon, which breeds carbon dioxide to produce methane. So where on Earth do we geologists look?
“One problem doing that kind of field research,” Chapelle explained, “is that the earth is so heavily permeated with the effects of photosynthesis. It’s very hard to find anywhere on our planet that is not contaminated with organic carbon or by molecular oxygen both generated by photosynthesis, resulting from sunlight.
“Sunlight is the primary energy source for life on earth,” observed Lovley. “Plants convert the sun’s energy to organic matter that other organisms then use for fuel. On Mars, or Jupiter’s moon Europa, and other planets or moons on which life might exist in our solar system, liquid water required by life is available only below the surface where the sun doesn’t shine. So if there is life, it must sustain itself with alternative energy sources. This study in Nature demonstrates for the first time that certain microorganisms can thrive in the absence of sunlight by using hydrogen gas released from deep in Earth’s surface as their energy source.”
Chapelle found that source and those microorganisms beginning five years ago at Lidy Hot Springs in southern Idaho.
“The spring has been there probably for 3 or 4 million years,” he said. “In the past it was a commercial spa, but is not now. The owner wanted to control the spring’s flow, as he uses the geothermal water [132 degrees F] to heat his buildings and generate electricity. In order to capture the flow, he drilled numerous bore holes down into the underlying rhyolite volcanic bedrock. At our request, he instrumented a 6-inch-wide bore hole by lining it down a couple of hundred meters [600-plus feet] with PVC pipe to get water samples that hadn’t been contaminated at the surface.” The resulting analysis determined that Archaea in the water outnumbered bacteria 99 to 1.
“The microbial community we found at the Idaho site,” Lovley pointed out, “is remarkably similar to what might be found below the surface of Mars. Now we can use our discovery to test hypotheses about hydrogen-based subsurface life, and develop strategies to search for similar microbial communities on other planets.”
Mice With Ataxic And Eye Symptoms Of Severe Vitamin E Deficiency Benefit By Its Restoration
Various vegetable oils, whole grain cereals and lettuce provide vitamin E also known as tocopherol in the diet. Its deficiency produces abortion in female rats and sterility in males. Extreme vitamin E deprivation in humans causes ataxia loss of muscle coordination. This is an autosomal recessive disease called ataxia vitamin E deficiency (AVED), often confused with Friederich ataxia, the commonest hereditary ataxia in Europe and North America.
Vitamin E is one of the most potent fat-soluble oxidants. A tocopherol transfer protein, a-TTP, helps maintain vitamin E levels in blood and body tissues. Japanese neuropathologists have detected mutations in the human gene for that protein in patients with AVED. They found these mutations to be a cause of retinitis pigmentosa as well as ataxia. The researchers tested the absence of the protein in knockout mice. Their report, in the Proceedings of the National Academy of Sciences (PNAS), dated Dec. 18, 2001, is titled: “Delayed-onset ataxia in mice lacking a-tocopherol transfer protein: Model for neuronal degeneration caused by chronic oxidative stress.”
These animals showed progressive ataxia and retinal degeneration beginning at 1 year of age without vitamin E, and these symptoms were reversed after they received supplemental vitamin E.
New Data On p53’s Molecular Strategy As Tumor Suppressor, Failure When Its Gene Is Mutated
Mutant variants of the tumor-suppressor p53 protein occur in more than half of all human cancers. The innocuously named protein p53 is a vital factor in regulating cell growth in the body, thus manning one of its strongest barricades against the uncontrolled growth of malignant tumors.
A paper in the journal Molecular Cell, dated December 2001, identifies an orchestrated series of molecular modifications to p53 essential for it to initiate the transcription of genes involved in growth control. The article is titled: “Acetylation of p53 activates transcription through recruitment of coactivators/histone acetyl transferases.”
“Our findings show that p53’s ability to suppress tumors depends on a cascade of molecular changes that occur after the molecule binds to the DNA,” observed molecular geneticist Shelley Berger, at the Wistar Institute in Philadelphia. “The data also outline,” she added, “a general mechanism by which many DNA-binding proteins, including other transcription factors like p53, might be regulated. These findings,” Berger concluded, “may suggest new ways to combat an array of cancers in which p53 is dysfunctional.”