Functional genomics

Open-reading frame sequence tags (OSTs) support the existence of at least 17,300 genes in C. elegans. Reboul, J. et al. Nature Genet. 27 , 332–336 (2001) [PubMed]

Homology-based annotation yields 1,042 new candidate genes in the Drosophila melanogaster genome. Gopal, S. et al. Nature Genet. 27 , 337–340 (2001) [PubMed]

The sequencing of several eukaryotic organisms' genomes has allowed new estimates of their gene number to be made — and there have been some surprises. Humans have fewer genes than expected, and worms have 50% more genes than flies have. The problem is that the tools used to make the predictions are not 100% reliable. Reboul et al. use an experimental strategy to test ∼1,000 of the gene predictions in C. elegans, and find supporting evidence for 70%. Gopal et al. use a bioinformatic strategy to closely look at the Drosophila genome and find evidence for 1,000 more genes. So, the difference (in gene number) between flies and worms might not be so large after all.

Plant genetics

Self incompatibility in the genus Arabidopsis : characterization of the S locus in the outcrossing A. lyrata and its autogamous relative A. thaliana. Kusaba, M. et al. Plant Cell 13 , 1–18 (2001) [PubMed]

Molecular studies of self incompatibility in the Brassica species have identified a gene complex, S, that controls their inability to self pollinate. To address how this complex evolved, these authors sequenced two S-locus genes from the self-incompatible (SI) A. lyrata plant. A phylogenetic analysis of these genes and their orthologues in the self-compatible A. thaliana and other SI Brassica species revealed that this locus has undergone several duplications since the Arabidopsis –Brassica split, and that self compatibility in A. thaliana is due to the inactivation of S-locus genes.

Expression profiling

Delineating developmental and metabolic pathways in vivo by expression profiling using the RIKEN set of 18,816 full-length enriched mouse cDNA arrays. Mika, R. et al. Proc. Natl Acad. Sci. USA 27 , 2199–2204 (2001) [PubMed]

In one of the first large-scale uses of this recently published resource (see In Brief in last month's issue), RIKEN researchers have arrayed almost 19,000 full-length, mouse cDNAs to analyse the expression profiles of 49 adult and embryonic mouse tissues. Cluster analysis identified sets of genes that were expressed ubiquitously or in similar groups of tissues and revealed that metabolic pathways are coordinately regulated throughout the mouse during development and adulthood. These expression profiles are available at a RIKEN database called READ.