Microfluidics

Understanding the curious mating habits of yeast

The mitogen-activated protein kinase (MAPK) pathway in Saccharomyces cerevisiae is responsible for sensing mating pheromones sent out by other yeast cells. To investigate the quantitative regulation of the MAPK-regulated yeast pheromone response, Paliwal et al. developed a unique microfluidic device, which allowed them to load cells into test chambers, expose them to linear concentration gradients of pheromone, and monitor gene expression and phenotypic changes in individual cells.

Paliwal, S. et al. Nature 446, 46–51 (2007).

Proteomics

Label-free analysis of protein complexes

Rinner et al. describe MasterMap, a computational platform to aid in the quantitative analysis of protein complexes with label-free mass spectrometry. MasterMap is used to collect and compare multiple mass spectral analyses of protein complexes isolated via coimmunoprecipitation. Spectral features that differ from run to run, representing changes in interactions of the complex, can be selected for further analysis by tandem mass spectrometry. The approach is promising for large-scale protein interaction network mapping.

Rinner, O. et al. Nat. Biotechnol. 25, 345–352 (2007).

Genomics

SNP discovery in non-model organisms

Single nucleotide polymorphisms (SNPs) are the most common type of genetic mutation. For non-model organisms with yet unsequenced genomes, however, SNP discovery is extremely difficult. Orsini et al. describe a method to detect and isolate SNP markers by exploiting the ability of the Mu transposition machinery to target mismatched DNA sites. The method led them to find 164 SNPs in the genome of the Glanville fritillary butterfly.

Orsini, L. et al. Nucleic Acids Res.; published online 20 February 2007.

Cell Biology

Crossing biological barriers with nanotubes

Carbon nanotubes are hot scientific property, with touted potential applications ranging from the industrial to the therapeutic. In a preliminary step toward characterizing their therapeutic potential, Kostarelos et al. performed an extensive study investigating the uptake of functionalized carbon nanotubes in a variety of cell types, including yeast and fungi.

Kostarelos, K. et al. Nat. Nanotechnol. 2, 108–113 (2007).

Spectroscopy

ssNMR spectroscopy for whole biological assemblies

Magic-angle spinning solid-state NMR (MAS ssNMR) spectroscopy is used in determining the structures of molecules that cannot easily be dissolved in solution, for example, of membrane-bound proteins. By using MAS ssNMR, Goldbourt et al. determined the secondary structure of the major coat protein subunit of the filamentous bacteriophage Pf1 on the intact phage, which retained infectivity after the NMR experiment.

Goldbourt, A. et al. J. Am. Chem. Soc. 129, 2338–2344 (2007).