Gene Regulation

Substrate-induced gene expression screening of environmental metagenome libraries for isolation of catabolic genes

Uchiyama et al. present a new technique for the identification of genes induced by a catabolite of interest: substrate-induced gene expression screening (SIGEX). Genomic fragments from an organism of interest are cloned into an operon-trap GFP expression vector, and FACS is used to separate clones in which the presence of a particular catabolite induces expression.

Uchiyama, T. et al. Nat. Biotechnol., 23, 88–93 (2005).

Virology

Synchronized infection of cell cultures by magnetically controlled virus

Current strategies for the retroviral infection of cultured cells rely on the diffusion of viral particles. By coating lentivirus with iron oxide nanoparticles and using a magnetic field to draw the coated viruses to the cell monolayer, Haim et al. demonstrate a dramatically enhanced rate of association, suggesting the possibility of tightly synchronized studies of the infection process.

Haim, H. et al. J. Virol. 79, 622–625 (2004).

Imaging and Visualization

Tumor imaging by proteolytic activation of cell-penetrating peptides

Previous studies have demonstrated that relatively simple cell-penetrating peptides (CPPs) can facilitate passage through cell membranes by an associated 'cargo' molecule. Jiang et al. further enhance this technology, creating CPPs that rely on proteolytic cleavage for activation and demonstrating their capacity to label tumor cells.

Jiang, T. et al. Proc. Natl. Acad. Sci. USA 51, 17867–17872 (2004).

DNA Cloning and Amplification

Accurate multiplex gene synthesis from programmable DNA microchips

Oligonucleotide synthesis can be a costly and error-prone process. Tian et al. present a microarray-based strategy for the rapid and affordable synthesis, amplification and purification of oligonucleotides. They demonstrate the rapid production of highly accurate oligonucleotides and their application to the synthesis of a variety of full-length genes.

Tian, J. et al. Nature 432, 1050–1054 (2004).

Genomics

Global identification of human transcribed sequences with genome tiling arrays

Bertone et al. demonstrate the use of a human genome tiling array for the large-scale investigation of transcriptional activity. cDNA derived from liver mRNA was hybridized against arrays representing roughly 1.5 Gb of nonrepetitive genomic sequence, confirming numerous known and predicted genes, and revealing over 10,000 previously unidentified transcribed sequences.

Bertone, P. et al. Science 306, 2242–2246 (2004).