Sex and the single chromosome

Adv Genet. 2002;46:1-24. doi: 10.1016/s0065-2660(02)46002-6.


Just as homology can trigger a chain of events as described in many of the chapters of this volume, sometimes a lack of homology causes a crisis of a different sort. So it is for the single X chromosome in XY males in many species. Divergent sex chromosome pairs, such as the X and Y chromosomes in mammals and in fruit flies, are thought to have evolved from homologous autosomes. During evolution, the Y chromosome has retained little coding capacity, leaving the male with reduced gene dosage for many functions encoded by the X chromosome. In this chapter we focus on dosage compensation in Drosophila, in which most X-linked genes are upregulated by a male-specific ribonucleoprotein complex. This complex is thought to recognize the X chromosome through approximately 35 dispersed chromatin entry sites and then spread in cis to dosage compensate most genes on the X chromosome.

Publication types

  • Comparative Study
  • Review

MeSH terms

  • Animals
  • Biological Evolution
  • Chromatin / genetics
  • DNA-Binding Proteins
  • Dosage Compensation, Genetic
  • Drosophila / genetics
  • Drosophila Proteins / genetics
  • Female
  • Male
  • Mammals / genetics
  • Models, Genetic
  • Nuclear Proteins / genetics
  • Protein Biosynthesis
  • Sex Chromosomes / genetics*
  • Sex Determination Processes
  • Transcription Factors / genetics
  • Y Chromosome / genetics


  • Chromatin
  • DNA-Binding Proteins
  • Drosophila Proteins
  • Nuclear Proteins
  • Transcription Factors
  • msl-2 protein, Drosophila