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Awards in Focus Chromosome segregation in the Archaea domain of life Archaea evolved as the third domain of life billions of years ago, but they are a relatively recent addition to the map of the universal tree of living organisms. Their discovery 34 years ago represented a major biological milestone. Archaea are unicellular organisms that populate our planet together with bacteria and eukaryotes. Both bacteria and Archaea are prokaryotes, i.e. their genetic material is not wrapped by a membrane into a separate compartment, called nucleus, which is instead a defining hallmark of eukaryotes (baker yeast, fungi, algae, plants, animals and humans to mention some). Initially isolated from extreme ecosystems, Archaea are now known to be ubiquitous, constituting a considerable fraction of the biosphere. For example, it has been reported that the world ocean alone contains approximately 1.3 x 1028 archaeal cells; this is an enormous number. To provide a comparison, the estimated number of grains of sand on all the beaches on earth is 7.5 x 1018, a quantity still much smaller as compared with that of marine archaeal cells. Their ubiquity and abundance make them key players in regulating global biogeochemical cycles on Earth. From a functional and mechanistic standpoint, Archaea are a mosaic of tesserae from bacteria and eukaryotes, but they are also characterised by unique molecular features like methane production. Hyperthermophilic archaea are super microbes thriving at 80ºC and higher temperatures in hot springs, volcanoes, deep sea vents and exhibiting unusual properties, which make these organisms valuable for the development of novel biotechnological applications, but also extremely interesting for basic studies on life pushed to extremes. Despite the significant progress made in decoding molecular mechanisms in these organisms in the last three decades, to date no information is available on the fundamental process of chromosome segregation in Archaea and the subject remains a black box awaiting investigation. Genome segregation is a crucial stage of the life cycle of every cell; the genetic material is first duplicated, then separated and equally distributed into the two daughter cells. We intend to analyse this process in the hyperthermophilic archaeon Sulfolobus solfataricus (see figure below), whose genome harbours genes that encode excellent candidates for a minimalist chromosome segregation machine. The project will exploit in vivo and in vitro approaches to construct a multifaceted picture of the chromosome segregation engine of S. solfataricus. We will start with genetics: the classic genetic method to discover the function of a gene is to delete it from the genome and examine which defects emerge in the organism under scrutiny. We will delete the candidate genes and inspect the phenotype (‘observable characteristics’ from the Greek verb ‘phainein’ meaning ‘to appear’) of the mutant S. solfataricus cells by fluorescence microscopy. The proteins encoded by the candidate genes will then be probed by undertaking biochemical and biophysical investigations. The blend of interdisciplinary approaches will ensure exciting contributions to unravel the molecular mechanisms underpinning chromosome segregation in Sulfolobus species, paving the way toward a more systematic exploration of this topic in the third domain of life. Dr Daniela Barillà University of York Daniela was awarded a Research Project Grant in June 2011; providing £143,618 over 36 months. Sulfolobus solfataricus cells. (A) Cells stained with a fluorescent dye called DAPI that binds to their chromosome. (B) Bright field micrograph of the same cells. (C) Overlay of DAPI-stained and bright field images. Scale bar = 1µm. Images courtesy of Brett McLeod.