In the December 18 Proceedings of the National Academy of Sciences, Xavier Morin and colleagues describe a gene-trap strategy that generates green fluorescent protein (GFP) fusions and allows the study of protein distribution and subcellular localization in living flies (Proc Natl Acad Sci USA 2001, 98:15050-15055).They created a protein-trap transposon (PTT), a P element containing an artificial exon encoding GFP and flanked by splice acceptor and donor sequences. They derived over 600 fluoresc

Arbuscular mycorhizal fungi, which have lived for 400 million years without sex, present a challenge to evolutionary theories about the role of sex. In the December 13 Nature Gerrit Kuhn and colleagues at the University of Lausanne, Switzerland, discuss genetic variation within Arbuscular mycorhizal fungus individuals, which contain hundreds of inherited nuclei (Nature 2001, 414:745-748).They carried out specific DNA-DNA FISH (fluorescent in situ hybridization) analysis to show that fungal spore

The parasite Trypanosoma brucei can exploit antigenic variation of its VSG coat proteins to avoid detection by the mammalian host. In the December 13 Nature, Miguel Navarro and Keith Gull from the University of Manchester, UK, provide a mechanism for mono-allelic VSG expression (Nature 2001, 409:759-763).They investigated the role of RNA polymerase I (pol I) and nuclear compartmentalization in VSG expression. They used antibodies against T. brucei pol I, to identify a 'pol I body' outside the nu

The vast majority of genes in the yeast genome are non-essential suggesting significant functional redundancy. In the December 14 Science, Amy Tong and colleagues describe an approach for high-throughput synthetic-lethal analysis in yeast (Science 2001, 294:2364-2368).They developed an ordered array of about 4,700 viable gene-deletion mutants and generated haploid double-mutants; they called this strategy synthetic genetic array (SGA) analysis. Tong et al. tested a query strain with a deletion i

Telomeres protect the ends of chromosomes and prevent chromosomal end-to-end fusions. The DNA-dependent protein kinase (DNA-PK) has been implicated in DNA repair and telomere maintenance. In the December 18 Proceedings of the National Academy of Sciences, David Gilley and colleagues at the Lawrence Berkeley National Laboratory report the use of knockout mice to examine the function of the DNA-PK catalytic subunit (Proc Natl Acad Sci USA 2001, 98:15084-15088).Analysis of fibroblast and primary cu

The mechanisms underlying the innate immune system are highly conserved from flies to mammals. In the December 18 Proceedings of the National Academy of Sciences, Phil Irving and colleagues describe a genome-wide screen for genes induced in Drosophila following infection with bacteria or fungi (Proc Natl Acad Sci USA 2001, 98:15119-15124).They performed oligonucleotide-array gene-profiling analysis on material from flies inoculated with Gram-negative or Gram-positive bacteria or with the fungi B

Adeno-associated virus is an attractive vector for gene therapy as it is non-pathogenic and integrates into a specific site in the human genome. In the December 11 Early Edition of the Proceedings of the National Academy of Sciences, Toni Cathomen and colleagues, at The Salk Institute for Biological Studies in California describe a genetic screen for cellular proteins that can bind to a viral DNA sequence important for replication and integration (Proc Natl Acad Sci USA, 2001 10.1073/pnas.261567

Non-invasive imaging of reporter gene expression offers a powerful tool for monitoring spatial and temporal expression in live animals (or people). One limitation of such techniques is the low expression of genes driven by tissue-specific promoters. In the December 4 Proceedings of the National Academy of Sciences, Iyer et al. describe using a two-step transcriptional amplification (TSTA) approach to amplify the signal for non-invasive detection (Proc Natl Acad Sci USA 2001, 98:14595-14600).They

Two genes have been found to down-regulate the non-homologous end-joining pathway in meiotic diploid yeast cells.

Some transposable elements can be beneficial and others may persist in the genomes of sexually reproducing eukaryotes even if they are deleterious. In the December 4 Proceedings of the National Academy of Sciences, Irina Arkhipova and Hilary Morrison report the characterization of retrotransposons in the Giardia lamblia genome (Proc Natl Acad Sci USA 2001, 98:14497-14502).G. lamblia is a protozoan parasite, one of the earliest-branching eukaryotes, and is thought to be asexual. Arkhipova and Mor

The genes down-regulated by the glial cell-line-derived neurotrophic factor may account for the factor's inhibition of neurite growth.

Transcript profiling identifies groups of genes associated with different developmental stages during the formation of wood in trees.