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Genome-wide analyses of transcriptional output in eukaryotes have revealed an unanticipated transcriptome complexity. These findings imply a complex, interleaved genomic organization, in which individual sequences carry multiple and overlapping informational content. The authors discuss the evidence for, and functional and evolutionary consequences of, this organization.
Genome-wide discovery and characterization of core promoters has revealed that most mammalian genes are transcribed from multiple promoters, each of them starting from multiple nucleotide positions, not directed by a TATA box. The authors propose a new classification of promoters.
Powerful tools for carrying out large-scale genetic-interaction screens have made budding yeast a leading model system for understanding gene networks. Studies in yeast also provide a basis for extending our understanding to networks in more complex eukaryotes.
The transcription regulation networks that control gene expression consist of a series of recurring logical wiring patterns — network motifs. By understanding the properties of these simple motifs we can start to understand the complexity of whole networks.
Although they do not get cancer naturally, genetically manipulatedDrosophila melanogasterare a useful model for studying tumours. Recent results highlight the importance of asymmetric cell division and proper spindle alignment for preventing stem cells from giving rise to tumours.
Some structures, such as mammalian forelimbs and bird wings, are obviously homologous, but the basis of this is often elusive as the developmental genes involved are not homologous. The author argues that it is instead the gene regulatory networks that are homologous.
New approaches to the derivation of human embryonic stem cells are being developed, with the aim of getting around the ethical questions that surround standard techniques. But are any of these new methods really free from ethical objections?
