Hox genes are a group of approximately 40 genes that control the anterior-posterior axial development in all animals that show such polarity. Much interest surrounds the precise regulation of this complex patterning, which depends inter alia upon qualitative and quantitative differences in Hox gene product levels in different tissues at different times. The expression pattern of this group of genes is described as temporal colinearity—genes are expressed in time in the same order that they appear on the genome—but the mechanism by which this transcription ordering is achieved has been unclear. In the July 15
Cathy Holding(cholding@hgmp.mrc.ac.uk)