Evolution

Drosophila pigmentation evolution: divergent genotypes underlying convergent phenotypes. Wittkopp, P. J. et al. Proc. Natl Acad. Sci. USA 100, 1808–1813 (2003)

In this quantitative trait analysis, at least four loci were identified by marker association that contribute to the different pigmentation patterns that are observed in Drosophila novamexicana and Drosophila americana. Although the pigmentation in these species is similar to that seen in other Drosophila species that have been studied, the genetic basis of the convergent phenotypes is different. Of the four loci found, only one (ebony) had been previously associated with interspecific variation in pigmentation, showing that convergent phenotypes can result from divergent genotypes.

Gene Regulation

Genome-wide identification of in vivo Drosophila Engrailed-binding DNA fragments and related target genes. Solano, P. J. et al. Development 130, 1243–1254 (2003)

After ultraviolet crosslinking of DNA–protein interactions, the authors used a chromatin immunoprecipitation protocol to find potential targets of Engrailed in the Drosophila genome. There were 203 Engrailed-binding fragments situated in intergenic or intronic regions, and the putative target genes that were located near these binding sites were found to be involved in a wide range of developmental processes. Engrailed regulation was confirmed for 12 of the 14 genes, including frizzled2, by examining their expression in flies that ectopically expressed engrailed.

Technology

DNA molecule provides a computing machine with both data and fuel. Benenson, F. et al. Proc. Natl Acad. Sci. USA 4 March 2003 (10.1073/pnas.0535624100)

A discrete self-assembled metal array in artificial DNA. Tanaka, F. et al. Science 299, 1212–1213

Fifty years after the structure of DNA was determined, its unique chemical properties are increasingly being put to good use. Two new studies take advantage of DNA's highly selective base pairing to use it as a building block for supramolecular ensembles. By replacing hydrogen-bonded base pairs in the double helix with metal-bonded base pairs, Tanaka et al. assemble an array of five Cu2+ in the middle of the DNA. Uniquely, this method allows metal ions to be arrayed in solution and opens up the possibility of DNA-based nanodevices such as molecular magnets and wires. Benenson et al. focus on the potential of DNA for molecular computing. For the first time, they show that the energy generated by hydrolysis of the DNA backbone can drive a molecular computation. The authors suggest that the ability of DNA to act as an energetically efficient information-processing device helps to explain its selection as the mechanism for genetic information transfer.