Caloric restriction (CR) is known to extend life-span in many species, and is thought to work by slowing metabolism and thus the generation of toxic reactive oxygen species. In the 22 September Science Lin et al. report that yeast also grow longer under conditions of CR (Science 2000, 289:2126-2128). Yeast on low-glucose plates, or with a defect in the glucose-activated protein kinase A (PKA) pathway, divide for more generations before senescing. The histone deacetylase and silencing protein Sir

The nuclei used in cloning may not go through all the changes that normally reset a gamete nucleus, and thus there have been fears of premature aging and shortened telomeres (an age-related phenomenon) in cloned animals. Indeed, shortened telomeres have been seen in cloned sheep, although the reverse is true for cloned cows. Now in the 21 September Nature Wakayama et al. report that mice reiteratively cloned for up to six generations show no signs of premature aging or shortening of telomeres (N

The expression of Wnt signaling proteins in the head organizer of Hydra, a freshwater polyp, suggests that Wnt was central in the evolution of axial differentiation.

Worm proteins required for nonsense-mediated mRNA decay are also required for maintenance of RNA interference.

Cuckoos lay eggs that mimic the eggs of other bird species; those eggs are then looked after by the unsuspecting foster parent. Cuckoos have been divided into races based on the identity of the egg type that the females mimic. In the 14 September Nature Gibbs et al. report that only female cuckoos observe 'race' boundaries (Nature 2000, 407:183-186). Mitochondrial DNA, which is passed solely through the female line, occurs in race-specific haplotypes. But nuclear DNA, which segregates through bo

The 2000 Albert Lasker Medical Research Awards, announced in New York on September 17, will put further pressure on the Nobel Foundation to grant a Nobel Prize for work related to the cell cycle.

Molecular phylogenies of bacteria are mostly built on the analysis of conserved molecules such as 16S ribosomal RNA. But there is evidence for horizontal gene transfer of photosynthesis genes, so any debate about the origin of photosynthesis must look directly at the evolution of that gene group, independent of its bacterial host. This is what Xiong et al. undertake in the September 8 Science, using 100 kb of newly generated sequence that identifies many genes for photosynthetic pigment synthesi

Proteins of the major histocompatibility complex (MHC) are involved in cell-cell recognition: they bind and present antigens in the immune system. But, at least in mice, they are also involved in odor-based recognition between individuals. Mice tend to mate with MHC-dissimilar mice (to maintain MHC diversity) and nest with MHC-similar mice. In the September 12 Proceedings of the National Academy of Sciences Yamazaki et al. report that mothers recognize and preferentially retrieve MHC-similar pup

Two papers in the September 8 Science are a testament to the speed at which biological chip formats and standards are evolving. Taton et al. expand on their established method for detecting DNA hybridization using gold nanoparticles attached to a probe (Science 2000, 289:1757-1760). The previous system took advantage of a color change induced upon nanoparticle aggregation, but a new method of nanoparticle-promoted reduction of a silver(I) substrate allows for signal amplification and detection u

In the 7 September Nature Shigenobu et al. report the complete sequence of Buchnera, an obligate resident of aphid cells (Nature 2000, 407:81-86). The sequence suggests that this bacterium is on its way to becoming an organelle. Buchnera looks most like Escherichia coli, but with a genome one seventh the size. It lacks genes for most regulatory proteins and for the biosynthesis of nonessential amino acids, cell-surface components (including lipopolysaccharides and phospholipids), and crucial DNA

Protein arrays are lagging behind in their implementation relative to DNA arrays because proteins are harder to produce and keep active. But in the September Nature Biotechnology de Wildt et al. describe the use of robotic spotting to produce antibody arrays, using bacterial colonies that produce single-chain antibodies (Nat. Biotechnol. 2000, 18:989-994). Up to 18,342 antibody clones can be screened at one time, and the same antibody-producing cells can easily be spotted onto up to 15 replicate

In the 1 September Science Lang et al. argue that two single-domain biosynthetic enzymes appear to have evolved from gene duplication, followed by fusion, followed by a second gene duplication (Science 2000, 289:1546-1550). Both of the proteins, HisA and HisF, can be broken down into two half beta/alpha barrels. The four half barrels can be superimposed on each other, revealing 22% identical or similar residues. As both enzymes bind biphosphate substrates, each half barrel has a phosphate-bindin