The chromosome geographer A public meeting with biologist Thomas Cremer at SISSA 21 October 2013 Wednesday 23 October, 2.30 pm, Main Lecture Hall, SISSA Among the most interesting discoveries in recent decades, the one that cellular DNA does not appear as a shapeless tangle, but rather is arranged into discrete “geographic” territories may be considered truly revolutionary. The first to suggest these chromosome “maps” was Thomas Cremer, a scientist whose studies represent a milestone in the fields of biology and genetics. Cremer will be giving a public lecture at SISSA, on Wednesday October 23. When DNA is not condensed in the shape of a double rod (that is, for most of its lifetime) it is diluted inside the cell nucleus in an apparently messy tangle. Biologists had long suspected that there might be some order to that mess, but they had to wait for Thomas Cremer’s studies to demonstrate it and suggest that this arrangement served a specific function. The cells of our body are, in fact, differentiated by function (for example, liver cells behave in a completely different manner from nerve cells). This difference lies in the ability of a certain cell type to synthesize a given range of proteins, depending on its function. And yet, to some extent, “all cells are born the same”, since they all contain the individual’s complete genome (at least all somatic cells do, while gametes contain only half). What changes is the portion of DNA which is active in the process of protein synthesis in each type of cell. Cremer’s merit has been to understand that the geographic arrangement of DNA has to do with the turning on and off of genes. For example, the regions that are most “tightly packed” are the least active ones, while the opposite is true for those where the mesh appears looser. Cremer is also one of the pioneers of a DNA mapping technique known as fluorescence in situ hybridization (FISH), which has become a standard in laboratories that study DNA. The technique involves inserting molecules – which become fluorescent when illuminated with light at specific wavelengths – into DNA fragments to check whether these are active or silent. Cremer will be talking about all this at the colloquium to be held in the Main Lecture Hall of SISSA, on Wednesday October 23, at 2.30 pm. Cremer’s talk will be given in English. IMAGES: Nucleosome: Credits Richard Wheeler (Zephyris) 2005: http://bit.ly/1geU5l8 Contact: Press room: [email protected] Tel: (+39) 040 3787557 | (+39) 340-­‐5473118, (+39) 333-­‐5275592 via Bonomea, 265 34136 Trieste More information about SISSA: www.sissa.it