Immunochemistry

Using plants to make a better antibody

It is well known that the efficacy of an antibody can be influenced by modifying the glycosylation pattern. Cox et al. describe a new approach to optimize antibody glycan configuration by using a genetically modified aquatic plant, Lemna minor, in which several components of the glycosylation machinery have been silenced. This robust system led to the generation of antibodies with optimized activity, containing only a single major N-glycan species.

Cox, K.M. et al. Nat. Biotechnol. 24, 1591–1597 (2006).

Protein biochemistry

Experimental validation of computational design

In contrast to error-prone PCR, a more 'intelligent' way to introduce new function onto protein scaffolds is to use computational tools to design and optimize a library of alternative protein sequences. Few of these libraries, however, have been experimentally characterized. Treynor et al. report the systematic evaluation of seven library-design algorithms with the goal of introducing shifted fluorescence emission to GFP variants.

Treynor, T.P. et al. Proc. Natl. Acad. Sci. USA 104, 48–53 (2007).

Genomics

Sorting out Mos1 insertion mutants in worms

Mutants exist for about a quarter of Caenorhabditis elegans genes. As a complement to other large-scale mutant screens, Duverger et al. present a high-throughput approach to generating Mos1 transposon insertion mutants. Using a combination of fluorescence sorting, a liquid-handling robot and parallel cultivation of several thousand strains in liquid culture, they generated more than 17,500 homozygous insertional mutants.

Duverger, Y. et al. Nucleic Acids Res.; published online 12 December 2006.

Imaging and visualization

Imaging bacterial infections in vivo

Using near-infrared fluorescent zinc(II) dipicolyamine–based dyes that specifically target Gram-positive bacterial cell surfaces, Leevy et al. show that bacterial infections can be imaged in living mice at a tissue depth of more than two centimeters. They introduced the dye into the bloodstream of mice and found that it accumulated at a site of local Staphylococcus aureus infection.

Leevy, W.M. et al. J. Am. Chem. Soc. 128, 16476–16477 (2006).

Microfluidics

Optimizing experiments the microfluidic way

Using crystallization trials of membrane proteins as a proof-of-principle system, Li et al. demonstrate a simple microfluidics approach for simultaneous screening and optimization of experimental parameters in nanoliter volumes. They combined reagents in a controlled manner in microfluidic channels to generate hundreds of 10-nl droplets, each representing an individual experiment. They obtained protein crystals diffracting at 1.9–2.5 Å, validating the approach.

Li, L. et al. Proc. Natl. Acad. Sci. USA 103, 19243–19248 (2006).