A bird's-eye view of sex chromosome dosage compensation.
Intensive study of a few genetically tractable species with XX/XY sex chromosomes has produced generalizations about the process of sex chromosome dosage compensation that do not fare well when applied to ZZ/ZW sex chromosome systems, such as those in birds. The inherent sexual imbalance in dose of sex chromosome genes has led to the evolution of sex-chromosome-wide mechanisms for balancing gene dosage between the sexes and relative to autosomal genes. Recent advances in our knowledge of avian genomes have led to a reexamination of sex-specific dosage compensation (SSDC) in birds, which is less effective than in known XX/XY systems. Insights about the mechanisms of SSDC in birds also suggest similarities to and differences from those in XX/XY species. Birds are thus offering new opportunities for studying dosage compensation in a ZZ/ZW system, which should shed light on the evolution of SSDC more broadly.
Arnold
Arthur P
AP
Department of Physiological Science and Laboratory of Neuroendocrinology of the Brain Research Institute, University of California, Los Angeles, California 90095, USA. arnold@ucla.edu
Itoh
Yuichiro
Y
Melamed
Esther
E
D000818:Animals; D005075:Biological Evolution; D001717:Birds / Q000235:genetics*; D002645:Chickens / Q000235:genetics; D004303:Dosage Compensation, Genetic; D005260:Female; D053263:Gene Regulatory Networks; D006801:Humans; D008297:Male; D008957:Models, Genetic; D012730:Sex Chromosomes / Q000235:genetics*