From sequence to chromosome: The tip of the X chromosome of D. melanogaster

Abstract

One of the rewards of having a Drosophila melanogaster whole-genome sequence wilt be the potential to understand the molecular bases for structural features of chromosomes that have been a long-standing puzzle. Analysis of 2.6 megabases of sequence from the tip of the X chromosome of Drosophila identifies 273 genes. Cloned DNAs from the characteristic bulbous structure at the tip of the X chromosome in the region of the broad complex display an unusual pattern of in situ hybridization. Sequence analysis revealed that this region comprises 154 kilobases of DNA flanked by 1.2- kilobases of inverted repeats, each composed of a 350 - base pair satellite related element. Thus, some aspects of chromosome structure appear to be revealed directly within the DNA sequence itself.