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Lucas et al. report the visualization of V(D)J recombination of the immunoglobulin heavy-chain gene (Igh) in living pro-B cells. Despite the huge distances separating V coding sequences from D-J sequences (~2 Mb), the authors document an astonishingly rapid rate of remote associations. The key to speed is contraction of the Igh chromosomal domain. These findings provide a foundation for understanding long-range regulatory interactions in a variety of developmental processes, including the patterning of vertebrate limbs.

Comparative genome analyses reveal that organismal complexity scales not with gene number but with gene regulation. Recent efforts indicate that the human genome likely contains hundreds of thousands of enhancers, with a typical gene embedded in a milieu of tens of enhancers. Proliferation of cis-regulatory DNAs is accompanied by increased complexity and functional diversification of transcriptional machineries recognizing distal enhancers and core promoters and by the high-order spatial organization of genetic elements. We review progress in unraveling one of the outstanding mysteries of modern biology: the dynamic communication of remote enhancers with target promoters in the specification of cellular identity.

Research has been conducted on maternal Dorsal regulatory gradient in Drosophila embryo tissues. The characterization of Dorsal target enhancers has been carried out in investigating the basis for gene expression gradient thresholds, and the details are reported.

Recent research reveals that developmental aspects of ascidian larva and vetebrate tadpole demonstrate similarities at evolutionary and molecular levels. Data indicate that same genes are preferentially expressed in both ascidian and vetebrate notochord and nervous systems.

Results demonstrate that the cis-regulatory sequence termed the promoter targeting sequence (PTS) aids distal enhancers to overcome blocking by Fab-8 insulator. Data further suggest that PTS mediates conversion of dominant, long-rage insulators into local regulatory elements.

The novel Rel-containing gene in Drosophila, which is a dorsal-related immunity factor (Dif), is responsible for Drosophila's immunity. Dif is capable of binding CecA1 cecropin promoters kappa-B-like motifs. Dif proteins accumulate in the nucleus of larvae when it is damaged by manual puncture or injected with Escherichia coli. Dif is usually found in the cytoplasm of fat bodies.

The effects of the binding affinities and cooperative interactions of signaling molecules or transcription factors in cell fate specification during development were investigated. The study protocol involved site-directed mutagenesis combined with P transformation assays. The results showed that dosage-sensitive interactions between the dorsal morphogen (dl) and basic-helix-loop-helix proteins delimit threshold responses to the dl gradient, which initiates the formation of mesoderm, neuroectoderm and dorsal ectoderm during development.