Mitochondrial DNA (mtDNA) is ideal for evolutionary analysis because of lack of recombination, a high substitution rate, and maternal inheritance. Previous analyses have been limited to short stretches of mtDNA, but in the 7 December Nature Ingman et al. present results based on complete mtDNA sequences of 53 humans of diverse origins (Nature 2000, 408:708-713). The greater detail allows the derivation of a phylogenetic tree for the sequences. Two pieces of data (the genetic distance between hum

In the December Nature Biotechnology Selinger et al. use an Escherichia coli oligonucleotide array with 30-base-pair resolution to detect antisense transcripts, new open reading frames (ORFs), and transcription starts and stops (Nat Biotechnol 2000, 18:1262-1268). The 295,936 elements of the array do not come without their problems. The sheer size and complexity of the array means that there is a huge amount of cross hybridization detected by missense probes. But the use of many probes within th

In the December 5 Proceedings of the National Academy of Sciences, Zou et al. find that only some of the processes of aging in the fly can be explained by increased oxidative stress (Proc Natl Acad Sci USA 2000, 97:13726-13731). Zou et al. analyze expression profiles of both aging flies and young flies exposed to the free-radical generator paraquat, using microarrays of approximately 8000 expressed sequence tags (ESTs) that cover 30-40% of the Drosophila genome. Of these ESTs, 43 are upregulated

In the December Nature Biotechnology Schwikowski et al. combine the large-scale two-hybrid analyses of Uetz et al. and Ito et al. with other published two-hybrid results to come up with a total of 2,709 interactions encompassing 2,039 different yeast proteins. The synthesis of these results yields a single large network of 2,358 interactions among 1,548 yeast proteins, with the next largest network containing only 19 proteins (Nat Biotechnol 2000, 18:1257-1261). Connections between proteins assi

Plants that recognize a pathogen induce both a local defense response and a long-lasting, broad spectrum disease resistance throughout the plant, termed systemic acquired resistance (SAR). In the December Nature Genetics Maleck et al. use microarrays to monitor transcriptional changes during development of SAR (Nat Genet 2000, 26:403-410). Of the 10,000 expressed sequence tags (ESTs) on the microarrays, representing 25-30% of all genes from Arabidopsis thaliana, 413 show changes of 2.5-fold or m

In the 30 November Nature, Kopp et al. report that altered regulation of the bric-a-brac (bab) gene drove the evolution of sexually dimorphic pigmentation in Drosophila (Nature 2000, 408:553-559). The fifth and sixth abdominal segments (A5 and A6) of male Drosophila melanogaster are fully pigmented, whereas those of the female or of males of many other Drosophila species are only partially pigmented. The D. melanogaster males discriminate strongly against females with extra pigmentation, so the

A return to ancestral conditions can result in evolutionary reversal, but it is not inevitable.

A mutant fluorescent protein that changes from green to red over time can indicate when transcription is turned on and off.

In the November 21 Proceedings of the National Academy of Sciences, Peterson et al. describe a screen for chemicals that can be used to interfere with, and time, developmental events in zebrafish (Proc Natl Acad Sci USA 2000, 97:12965-12969). Zebrafish eggs were arrayed three to a well in 96-well plates, along with one of 1,100 synthetic small molecules. The developing embryos were screened once a day for three days for defects in the central nervous system, the cardiovascular system, pigmentat

Two-hybrid assays are great for detecting protein-protein interactions, but they scale as the square of the number of candidate interactions. Screening every possible interaction in yeast would require examining approximately 3.6 x 107 pairs, which is why previous large-scale screens by Uetz et al. and Ito et al. have pooled libraries of constructs. In the November 21 Proceedings of the National Academy of Sciences, Newman et al. find that such approaches can miss a great number of valid interac

The demand for insulin fluctuates with blood glucose levels, presenting a special challenge for would-be gene therapists. In the 23 November Nature, Lee et al. present their solution, which causes remission of autoimmune diabetes in mice for at least 8 months (Nature 2000, 408:483-488). A truncated insulin gene removes the need for proteolytic processing, a hepatocyte-specific, glucose-responsive promoter supplies the correct dosage, and an adeno-associated virus (AAV) delivers the necessary DNA

Inducing death in the mother of your future children may not be the wisest way to maximize your contributions to the gene pool. And yet male flies do just that: their sperm (or, more correctly, their seminal fluid) increases the death rate of recipient females. In the November 21 Proceedings of the National Academy of Sciences, Civetta and Clark suggest that the polygamous nature of fly society provides an explanation for this puzzling behavior. They find that male flies that induce a greater mo