Open AccessIncomplete dosage compensation in an evolving Drosophila sex chromosome.
Author(s) -
Ed Strobel,
Claus Pelling,
Norman Arnheim
Publication year - 1978
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.75.2.931
Subject(s) - dosage compensation , gene dosage , biology , chromosome , x chromosome , drosophila (subgenus) , genetics , autosome , rna , y chromosome , gene , x inactivation , gene expression
Cellular autoradiography was used to measure relative rates of chromosomal RNA synthesis and to examine the regulatory phenomenon of X-linked dosage compensation in Drosophila miranda, a species containing two distinct, nonhomologous X chromosomes (X1 and X2). The X1 chromosome was found to be dosage-compensated, since the rate of RNA synthesis along the single X1 chromosome in males equaled that of both X1 chromosomes in females. Unlike other sex chromosomes that have been studied, the more recently evolved X2 heterochromosome exhibited regional differences in transcriptional activity when males and females were compared. The distal 10% of the X2 was not dosage-compensated, whereas the majority of an interior segment, representing 30% of the X2 chromosome's length, was found to be dosage-compensated. Our data are consistent with the idea that the evolution of X2 dosage compensation has paralleled the differentiation of the X2 sex chromosome. In addition, gene rearrangement seems to have accompanied the acquisition of a dosage-compensory mechanism in the X2.