November 8, 2012 - Jackson Hole, Wyoming
Scientists believe that prior to the advent of DNA as the earth's primary genetic material, earlyforms of life used RNA to encode genetic instructions. What sort of genetic molecules did liferely on before RNA?
The answer may be AEG, a small molecule when linked into chains form a hypotheticalbackbone for Peptide Nucleic Acids, which have been hypothesized as the first geneticmolecules. Synthetic AEG has been studied by the pharmaceutical industry as a possible genesilencerto stop or slow certain genetic diseases. The only problem with the theory is that up tonow, AEG has been unknown from nature.
A team of scientists from the USA and Sweden announced that they have discovered AEGwithin cyanobacteria which are believed to be some of the most primitive organisms on earth.Cyanobacteria sometimes appear as mats or scums on the surface of reservoirs and lakesduring hot summer months. Their tolerance for extreme habitats is remarkable, ranging from thehot springs of Yellowstone to the tundra of the Arctic.
"Our discovery of AEG in cyanobacteria was unexpected," explains Dr. Paul Alan Cox, coauthoron the paper that appeared today in the journal PLOS ONE. The American team, is based at theInstitute for Ethnomedicine in Jackson Hole, and serve as adjunct faculty at Weber StateUniversity in Ogden, Utah.
"While we were writing our manuscript," Cox says, "we learned that our colleagues atthe Stockholm University Department of Analytical Chemistry had made a similar discovery, sowe asked them to join us on the paper."
To determine how widespread AEG production is among cyanobacteria, the scientists analyzedpristine cyanobacterial cultures from the Pasteur Culture Collection of Paris, France. They alsocollected samples of cyanobacteria from Guam, Japan, Qatar, as well as in the Gobi desert ofMongolia, the latter sample being collected by famed Wyoming naturalist Derek Craighead. Allwere found to produce AEG.
Professor Leopold Ilag and his student Liying Jiang at Stockholm University's Department ofAnalytical Chemistry analyzed the same samples and came up with identical results:cyanobacteria produce AEG. While the analysis is certain, its significance for studies of theearliest forms of life on earth remains unclear. Does the production of AEG by cyanobacteriarepresent an echo of the earliest life on earth?
"We just don't have enough data yet to draw that sort of conclusion," reports Cox. "However thepharmaceutical industry has been exploring synthetic AEG polymers for potential use in genesilencing, so I suspect we have much more to learn."
Source: Weber State University