In the December 19 Proceedings of the National Academy of Sciences, Kawashima et al. compare their sequence of Thermoplasma volcanium with existing genomic sequences of seven other archaeons, and find that thermophiles adapt to increasing heat by clustering purines and pyrimidines, and by making more basic proteins (Proc Natl Acad Sci USA 2000, 97:14257-14262). The frequency of purine or pyrimidine dinucleotides in the genomic sequences rises with increasing optimum growth temperature (OGT), as

Immunization with amyloid-beta peptide reduces the learning deficits seen in mouse models of Alzheimer's disease.

In the 15 December Science, Laub et al. find that a full 19% of the genome of the bacterium Caulobacter crescentus is subject to cell-cycle-specific regulation (Science 2000, 290:2144-2148). A surprising number of genes are induced, as in yeast, just before they are needed. Other genes, such as those directing the construction of the flagella and pilus, are induced in transcriptional cascades, with the order of induction reflecting the order of assembly of the respective apparatus. Laub et al. a

magazine's 'Person of the Year'.

In the 15 December Science, Vision et al. find that four large-scale duplication events, followed by gene loss, have shaped the Arabidopsis genome (Science 2000, 290:2114-2116). The duplication events are identified by first delineating 103 duplicated blocks containing seven or more genes. These duplicates are then assigned an age based on the sequence divergence between copies. The duplicates fall into four main age groups, all dating to the Mesozoic era (65 to 245 million years ago), which was

Previous analyses of the circadian clock in the plant Arabidopsis thaliana have turned up just a few genes regulated by the clock. In the 15 December Science, Harmer et al. use oligonucleotide-based arrays to find a vast new collection of clock-regulated genes (Science 2000, 290:2110-2113). Using probes derived from tissue harvested every four hours, and an array representing 8,200 different genes, Harmer et al. find that 453 genes (6%) fit a cosine test wave with a period between 20 and 28 hour

In the 15 December Science, Riechmann et al. compare transcriptional regulators from plants (Arabidopsis thaliana), animals (the worm Caenorhabditis elegans and the fly Drosophila melanogaster) and fungi (Saccharomyces cerevisiae). They conclude that new motifs, shuffled motifs, and old motifs put to new uses make plant transcriptional regulation very different from that found in other eukaryotes (Science 2000, 290:2105-2110). Arabidopsis has, by their estimation, 1,533 transcriptional regulator

gives us an idea of how plants function.

Haploid yeast cells bud next to the site of the previous division (axial pattern), but diploid yeast cells bud from their poles (bipolar pattern). In the 8 December Science, Chen et al. propose that the Rax2 protein marks the cortex to provide a landmark for bipolar budding (Science 2000, 290:1975-1978). Rax2 is an integral membrane protein, discovered following a hunt for mutants defective in bipolar budding. Late in the cell cycle, Rax2 protein localizes to rings associated with division sites

Male side-blotched lizards (Uta stansburiana) have three heritable throat colors, associated with three divergent mating strategies. In the 19 December Proceedings of the National Academy of Sciences, Zamudio and Sinervo find that these alternative mating strategies can stably coexist because, as in a game of rock, paper, scissors, each strategy has strengths over one other, and weaknesses in the face of the third (Proc Natl Acad Sci USA 2000, published online ahead of print). The strategy of bl

A slime mold, like metazoans, has a beta-catenin involved both in signaling and in forming adherens junctions.

Rhodopsin is essential for photoreceptor survival. In the 8 December Science Chang and Ready report that rhodopsin's essential function is to organize actin and thus direct the photoreceptor's morphogenesis (Science 2000, 290:1978-1980). An actin structure separates the photosensitive rhabdomere membranes from the rest of the cell; without this structure the cell collapses in on itself. Chang and Ready find that a dominant-negative Drosophila Rho guanosine triphosphatase, Drac1, mimics these deg