Large scale RNAi screens at low cost
Nature Methods
A cost-effective resource for RNA interference (RNAi) that allows the effective reduction of gene expression is presented online this week in Nature Methods.
RNAi is a process by which short stretches of RNA knock down the expression of specific genes. To trigger this process at will, scientists most commonly use synthetic so called small interfering (si)RNAs. Their advantage is that they can be designed to precisely target a sequence of choice within a gene; their disadvantage is that they are expensive. A large RNAi screen that targets many genes is thus financially impossible for a lot of academic laboratories. Frank Buchholz and colleagues have previously developed a method to generate siRNAs enzymatically, which makes them a lot cheaper but does not allow targeting of a particular sequence within a gene. Instead, the method creates a random pool of various siRNAs, some more effective than others, directed against a gene of interest. This presented a conundrum to many researchers who were intrigued by an easily accessible resource but doubted its efficacy in large screens. Buchholz and colleagues now introduce a selection step in their enzymatic synthesis process that makes the pool of enzymatically generated siRNAs more specific. The group shows that these enzymatically generated siRNAs work equally well, if not better than synthetic siRNAs in a large RNAi screen, at a fraction of the cost.
CONTACT
Frank Buchholz (Max Planck Institute of Molecular Cell Biology and Genetics
AG Buchholz, Pfotenhauer Str. 108, Dresden, 01307 Germany)
Tel +49 351 210 2888 E-mail: buchholz@mpi-cbg.de
Brain cells seen in context
Nature Methods
A microscopic technique that allows imaging of large tissue samples such as brain sections or whole embryos at good resolution is presented online this week in Nature Methods.
Many biologists are looking for ways to use microscopes to examine ever smaller objects, but this comes at the cost of losing the bigger picture, researchers for example, can see a tiny section of the brain at high resolution but information about the connections between different regions are lost. Hans Ulrich Dodt and colleagues now present a technique that allows imaging of large volumes while retaining a high-enough resolution to still see subcellular structures - such as the dendrites of neurons - within a large brain volume.
Their method has two essential components. One is submerging the tissue in a solution that scatters light in the same way the tissue does which allows light a clear passage through the sample. The other is illumination with a sheet of light coming from two sources at opposite sides of the sample. This allows a rapid scanning of the tissue across its three-dimensional structure and fast image acquisition. This technique will be important not only for neuroscientists to image connectivity in the brain but also for developmental biologists who want to study whole embryos.
CONTACT
Hans Ulrich Dodt (Max-Planck Institute, Munich, Germany)
Tel: +49 89 30622 344; E-mail: dodt@mpipsykl.mpg.de
PRESS CONTACTS
For North America and Canada
Katie McGoldrick, Nature Washington
Tel: +1 202 737 2355; E-mail: k.mcgoldrick@naturedc.com
For Japan, Korea, China, Singapore and Taiwan
Rinoko Asami, Nature Tokyo
Tel: +81 3 3267 8751; E-mail: r.asami@naturejpn.com
For the UK/Europe/other countries not listed above
Ruth Francis, Nature London
Tel: +44 20 7843 4562; E-mail: r.francis@nature.com
For media inquiries relating to editorial content/policy for Nature Methods, please contact the journal directly
Michael Eisenstein, Nature Methods (New York)
Tel: +1 212 726 9317; E-mail: methods@natureny.com
Nature Publishing Group (NPG) is a division of Macmillan Publishers Ltd, dedicated to serving the academic and professional scientific community. NPG's flagship title, Nature, is the world's most highly-cited weekly multidisciplinary journal and was first published in 1869. Other publications include Nature research journals, Nature Reviews, Nature Clinical Practice, and a range of prestigious academic journals, including society-owned publications.
NPG is a global company, with headquarters in London and offices in New York, San Francisco, Washington DC, Boston, Tokyo, Paris, Munich and Basingstoke. For more information, please go to www.nature.com
