Behavioural genetics

Molecular analysis of flies selected for aggressive behavior. Dierick, H. A. & Greenspan, R. J. Nature Genet. 13 August 2006 (doi:10.1038/ng1864)

This study shows that aggressive behaviour in fruitflies is associated with specific genetic changes. Selective breeding was used to create a population of fighting fruitflies, and differences in gene expression levels relative to an unselected control population were used to identify candidate genes. Mutant flies carrying a mutation in Cyp6a20, which encodes a cytochrome P450 that is a member of a protein family involved in the recognition of odour, were particularly aggressive, indicating that sensitivity to smell could be the trigger for violence.

Gene expression

Transcript-assisted transcriptional proofreading. Zenkin, N. et al. Science 313, 518–520 (2006)

The accuracy of RNA polymerase (RNAP)-mediated transcription is essential for error-free gene expression. Mechanistic studies using synthetic analogues of DNA–RNA elongation complexes show that RNAP has an intrinsic proofreading activity that is activated when a nucleotide is erroneously incorporated during RNA elongation. The misincorporated nucleotide stimulates hydrolysis of the penultimate phosphodiester linkage, and so participates in its own excision. These findings help to explain the fidelity of transcription, and suggest that a similar self-correcting mechanism might have allowed accurate replication of RNA genomes earlier in evolution.

Epigenetics

Human imprinted chromosomal regions are historical hot-spots of recombination. Sandovici, I. et al. PLoS Genet. 2, e101 (2006)

The authors used computational and biochemical approaches to investigate the relationship between the rates of human meiotic recombination and genomic imprinting. They found that imprinted regions had more linkage disequilibrium (LD) units and smaller haplotype blocks than flanking non-imprinted regions. Moreover, their detailed analysis of an imprinted region on chromosome 11 showed a remarkable correspondence between sites of meiotic recombination and steps in LD maps. These results support the role of specific sequences and epigenetic factors as determinants of recombination hot spots.

Systems biology

In vivo robustness analysis of cell division cycle genes in Saccharomyces cerevisiae. Moriya, H. et al. PLoS Genet. 2, e111 (2006)

Robustness is a property of biological systems that ensures their function when parameters such as gene expression levels or temperature are perturbed. To test the upper limit of gene expression levels, the authors devised a genetic screen in budding yeast called 'genetic tug-of-war'. ORFs were cloned into a plasmid with a copy number that normally exceeds 100; a reduced copy number indicated the upper expression limit of that gene under given conditions. When applied to cell-cycle-related genes, the method was used to evaluate and refine previously generated computer models of the cell cycle in yeast.