Figure 1: X chromosome dosage compensation. Dosage compensation balances expression of the X chromosomes between males and females and equalizes expression between the X and autosomes. In male flies, the single X chromosome is upregulated. C. elegans upregulates the X chromosomes in hermaphrodites and males, and the dosage compensation complex functions in hermaphrodites to downregulate transcription two-fold. The X chromosomes are upregulated in female and male mammals, but one X chromosome is inactivated in females. Green text indicates upregulation, and red text indicates downregulation. Yellow boxes depict chromosomes that are targeted by specific dosage compensation mechanisms.