EMBL – Annual Report 2011-2012
The Annual Report is published once a year in July after having been approved by EMBL Council. It covers the past academic year and puts research at EMBL into a broad context of current molecular biology to make it comprehensible to a wide, non-specialist audience. The Director General's Report covers important organisational and strategic aspects as well as the Director General's responses to the Scientific Advisory Committee reviews of EMBL Scientific Units that were carried out during the previous calendar year. The Scientific Report presents a selection of scientific stories from research at EMBL during the past year. It is written in a simple language to be understandable for a broad audience.
26 EMBL Annual Report 11·12 has come up with two analogous methods of suppressing the disruptive actions of transpo- sons: one locks transposon DNA into an inac- tive state by adding chemical tags called me- thyl groups so that they cannot jump around, whereas the other silences any rogue transpo- sons that might still roam the cell. These biological solutions for policing genom- ic vandals might sound simple, but their im- plementation is not — not surprising given the complexity of how transposons wreak genomic havoc in the first place. One method they use is a form of ‘copy and paste’ that, like normal gene expression, be- gins with the process of transcription, in which the DNA of a transposon is used as a template to produce a long RNA molecule. In ordinary gene expression, this RNA would contain the instructions for assembling a pro- tein, but transposon RNAs do not serve this purpose. Instead, they are used by an enzyme called reverse transcriptase to recreate the original DNA molecule, after which it can be pasted into another part of the genome. The new experiments focused on this intricate copy-and-paste variety of transposon, and the ways in which their activity is regulated. Previous research in fruit flies had suggested a complex picture of transposon regulation. In the first step, enzymes called Piwi proteins use their endonuclease or ‘slicer’ activity to cut Y ou may be deeply attached to the li- brary of books stored on your iPad or Kindle, but we all carry a much more profound digital library within our cells: our genome, which comprises 23 books (chro- mosomes) that together contain more than 25 000 chapters (coding genes). Yet the integrity of this library is under con- stant threat from genetic vandals called transposons. These are bits of DNA that can jump from location to location and insert themselves into meaningful paragraphs of genetic text, turning them into gibberish and rendering genes useless. Previous research has shown that a failure to keep transposon activity in check leads to sterility, so dealing with this threat is a biological priority. In two papers published back-to-back in Nature last year, three independent groups at EMBL-EBI, Monterotondo and Grenoble provided new insights into just how this is achieved. Both libraries and cells have to protect their precious stores of information. In a tradition- al library, valuable books can be preserved in a number of ways. Some may be locked in secure cases to prevent anyone getting their hands on them in the first place; in addi- tion, the library can hire guards to patrol the bookshelves to catch anyone who might wish to steal or deface their contents. The stud- ies reported in Nature suggest that evolution Guardians of the genome Libraries – of books and genes – need protection.