DOSAGE COMPENSATION IN FLIES AND WORMS - THE UPS AND DOWNS OF X-CHROMOSOME REGULATION

Dosage compensation ensures that individuals with a single X chromosom e have the same amount of most X-linked gene products as those with tw o. In Drosophila, this equalization is achieved by a two-fold enhancem ent of the lever of transcription of the X in males (XY) relative to e ach X chromosome in females (XX). In Caenorhabditis, equalization of X -linked gene products between hermaphrodites (XX) and males (XO) is ac hieved by decreasing the activity of genes in the former. These two di fferent solutions to the common problem of unequal dosage of X-linked genes in different sexes provide invaluable paradigms for the study of gene regulation at the level of chromatin remodeling. (C) Current Bio logy Ltd ISSN 0959-437X.