RNA interference

MicroRNA matchmaking

Computational microRNA target prediction programs usually yield a large number of targets for each microRNA, and deciding which to choose for validation is difficult. Grimson et al. describe five new features that determine the pairing of a microRNA to its target. These features are incorporated into their target-discovery algorithm, TargetScan, and will provide a more stringent selection for microRNA-target pairs.

Grimson, A. et al. Mol. Cell 27, 91–105 (2007).

Microscopy

Target-locking microscopy

Several microscope systems can target-lock an object and image it as it moves randomly in three dimensions. But these methods generally treat the object as a point, which makes the tracking of large complex objects such as cells difficult. Lu et al. describe target-locking acquisition with realtime confocal (TARC) microscopy that can follow a cell moving in three dimensions even as it changes shape, size and orientation.

Lu, P.J. et al. Optics Express 15, 8702–8712 (2007).

Genomics

Mapping an abundance of SNPs

By resequencing the genomes of 15 different laboratory mouse strains, including 11 classical and 4 wild-derived ones, Frazer et al. identified more than 8 million unique single-nucleotide polymorphisms (SNPs) across the mouse genome with oligonucleotide arrays. They used the data to generate an ancestral haplotype map, available online (http://mouse.perlegen.com).

Frazer, K.A. et al. Nature 448, 1050–1053 published online 29 July 2007.

Purification and separation

Assaying sisterly cohesion

Sister chromatid cohesion is an essential process during cell division, requiring a multiprotein complex called cohesin. Ivanov and Nasmyth developed an in vitro system based on sucrose gradient centrifugation and gel electrophoresis, which allowed them to directly show that the cohesin ring in yeast affects sister chromatid cohesion by trapping the sisters within its ring.

Ivanov, D. & Nasmyth, K. Mol. Cell 27, 300–310 (2007).

Biosensors

Artificial tongues made from synthetic pores

There has been considerable interest in developing 'electronic tongues' for understanding the biology of taste and for developing sensing applications. Litvinchuk et al. report a universal stimulus-responsive pore to detect flavor molecules by using the concept of 'reactive amplifiers': molecules that react with analytes to enhance their pore-blocking ability and thus amplify the pore response.

Litvinchuk, S. et al. Nat. Mater. 6, 576–580 (2007).