Year's comments for 2006.

The end of the twentieth century marked the beginning of a unique period in microbiology, such that microorganisms are now being studied from both ends of the biological spectrum: as the driving forces behind biological processes in the biosphere and as microscopic laboratories for studying these and other processes at the molecular level [2]. Microbes pervade most biological disciplines, and they have been the subject of increasing media attention due to both their positive and negative aspects. Thus, commenting on the achievements in the field of microbiology in 2006 as well as on the news related to microbiology published in the mass media would fill an entire issue of INTERNATIONAL MICROBIOLOGY. Therefore, let us focus on just a few of this year’s highlights. In its Year’s Comments for 2005, INTERNATIONAL MICROBIOLOGY noted the Nobel Prize in Physiology or Medicine, which was awarded to the discoverers of the role of Helicobacer pylori as the causal agent of gastric ulcers (Fig 1). In 2006, two Nobel Prizes (Physiology or Medicine, and Chemistry) were also related to microbiology. The Nobel Prize in Physiology or Medicine was awarded to Andrew Z. Fire, from Stanford University, and Craig C Mello, from the University of Massachusetts-Worcester, for their discovery of “RNA interference—gene silencing by double-stranded RNA”. Since this mechanism for controlling the flow of genetic information occurs in plants, animals, and humans, it may seem, at first glance, to have nothing to do with microbiology. However, RNA interference plays a major role in defending not only these organisms against viruses, but also “lower” organisms. In RNA interference, the presence of double-stranded RNA molecules in the cell triggers the biochemical machinery to degrade those mRNA molecules that carry a sequence identical to that of the doublestranded RNA. As a result, the mRNA from a specific gene is degraded. The disappearance of those mRNA molecules silences the corresponding gene, and the respective protein is no longer produced. Thus, cells infected by doublestranded RNA viruses are able to overcome the infection when the RNA of the infecting virus is degraded by means of RNA interference. The 2006 Nobel Prize in Chemistry was awarded to Roger Kornberg, from Stanford University, for his fundamental studies of the molecular basis of eukaryotic transcription. Kornberg has worked on transcription since 1974, when he was a postdoctoral student with Francis Crick and Aaron Klug, at the British Medical Research Council in Cambridge, UK. Kornberg chose Saccharomyces cerevisiae as the model organism for his research. The breakthrough Mercè Piqueras