Surprising new function for small RNAs in evolution. An international research team in including Christian Schlötterer and Alistair McGregor of the Vetmeduni Vienna has discovered a completely new mechanism by which evolution can change the appearance of an organism. The researchers found that the number of hairs on flies' legs varies according to the level of activity of a so-called microRNA. The results, published in the journal Current Biology, shed a completely new light on the molecular mechanisms of evolution. It has long been known that certain proteins, known as transcription factors, directly control the way in which information is read from DNA. As a result, it is widely believed that changes in genes encoding such proteins underlie the mechanisms responsible for evolutionary adaptation. The idea that small RNA molecules, so-called microRNAs, may play an important part in evolutionary changes to animals' appearance is completely new.
Small and large bald patches Schlötterer is naturally excited by the findings. Early-Earth cells modeled to show how first life forms might have packaged RNA. Researchers at Penn State University have developed a chemical model that mimics a possible step in the formation of cellular life on Earth four-billion years ago. Using large "macromolecules" called polymers, the scientists created primitive cell-like structures that they infused with RNA -- the genetic coding material that is thought to precede the appearance of DNA on Earth -- and demonstrated how the molecules would react chemically under conditions that might have been present on the early Earth.
The journal Nature Chemistry is posting the research as an Advance Online Publication on 14 October 2012. In modern biology, all life, with the exception of some viruses, uses DNA as its genetic storage mechanism. According to the "RNA-world" hypothesis, RNA appeared on Earth first, serving as both the genetic-storage material and the functional molecules for catalyzing chemical reactions, then DNA and proteins evolved much later. Ancient enzymes function like nanopistons to unwind RNA. Molecular biologists at The University of Texas at Austin have solved one of the mysteries of how double-stranded RNA is remodeled inside cells in both their normal and disease states.
The discovery may have implications for treating cancer and viruses in humans. The research, which was published this week in Nature, found that DEAD-box proteins, which are ancient enzymes found in all forms of life, function as recycling "nanopistons. " They use chemical energy to clamp down and pry open RNA strands, thereby enabling the formation of new structures. "If you want to couple fuel energy to mechanical work to drive strand separation, this is a very versatile mechanism," said co-author Alan Lambowitz, the Nancy Lee and Perry R.
Bass Regents Chair in Molecular Biology in the College of Natural Sciences and Director of the Institute for Cellular and Molecular Biology. "Once the second domain is latched on to the RNA," said Mallam, "and the first has got its ATP, the 'piston' comes down. Simpler times: Did an earlier genetic molecule predate DNA and RNA?
In the chemistry of the living world, a pair of nucleic acids -- DNA and RNA -- reign supreme. As carrier molecules of the genetic code, they provide all organisms with a mechanism for faithfully reproducing themselves as well as generating the myriad proteins vital to living systems. Yet according to John Chaput, a researcher at the Center for Evolutionary Medicine and Informatics, at Arizona State University's Biodesign Institute®, it may not always have been so. Chaput and other researchers studying the first tentative flickering of life on earth have investigated various alternatives to familiar genetic molecules. These chemical candidates are attractive to those seeking to unlock the still-elusive secret of how the first life began, as primitive molecular forms may have more readily emerged during the planet's prebiotic era.
Nearly every organism on earth uses DNA to encode chunks of genetic information in genes, which are then copied into RNA. Locked down, RNA editing yields odd fly behavior. At the level of proteins, organisms can adapt by editing their RNA -- and an editor can even edit itself. Brown University scientists working with fruit flies found that "locking down" the self-editing process at two extremes created some strange behaviors. They also found that the process is significantly affected by temperature.
Because a function of RNA is to be translated as the genetic instructions for the protein-making machinery of cells, RNA editing is the body's way of fine-tuning the proteins it produces, allowing us to adapt. The enzyme ADAR, which does this editing job in the nervous system of creatures ranging from mice to men, even edits itself. In a new study that examined the self-editing process and locked it down at two extremes in fruit flies, Brown University scientists found some surprising insights into how this "fine-tuning of the fine-tuner" happens, including bizarre behavioral effects that come about when the self-editor can't edit.
Take mating, for instance. 3-D RNA modeling opens scientific doors. Dokholyan lab researchers publish a paper in the April 16, 2012 issue of Nature Methods demonstrating the structure and function of RNA molecules and paving the way to develop targets for new therapeutics. In a paper published April 16, 2012 in the journal Nature Methods, a team from the University of North Carolina at Chapel Hill demonstrates a simple, cost-effective technique for three-dimensional RNA structure prediction that will help scientists understand the structures, and ultimately the functions, of the RNA molecules that dictate almost every aspect of human cell behavior.
When cell behavior goes wrong, diseases -- including cancer and metabolic disorders -- can be the result. Over the past five decades, scientists have described more than 80,000 protein structures, most of which are now publicly available and provide important information to medical researchers searching for targets for drug therapy. "With Dr. Strange cousins: Molecular alternatives to DNA, RNA offer new insight into life’s origins. Living systems owe their existence to a pair of information-carrying molecules: DNA and RNA. These fundamental chemical forms possess two features essential for life: they display heredity -- meaning they can encode and pass on genetic information, and they can adapt over time, through processes of Darwinian evolution. A long-debated question is whether heredity and evolution could be performed by molecules other than DNA and RNA.
John Chaput, a researcher at ASU's Biodesign Institute, who recently published an article in Nature Chemistry describing the evolution of threose nucleic acids, joined a multidisciplinary team of scientists from England, Belgium and Denmark to extend these properties to other so-called xeno-nucleic acids or XNAs. The group demonstrates for the first time that six of these unnatural nucleic acid polymers are capable of sharing information with DNA. Their results appear in the current issue of Science.