Public Release: 

Sex chromosomes have reverted to autosomes multiple times in flies

Results help explain puzzling features of 'dot chromosome'

Genetics Society of America

In previous research (Nature, July 2013), UC Berkeley scientists Beatriz Vicoso, Ph.D., and Doris Bachtrog, Ph.D., determined that genes on the so-called "dot chromosome," or fourth chromosome, of the fruit fly Drosophilia melanogaster are X-linked in three other related fly species.

These and other findings revealed that the fruit fly's "dot chromosome" had descended from a differentiated X chromosome and suggests that several of the chromosome's puzzling features are remnants of its heritage as a sex chromosome. For example, the expression levels of genes on the "dot chromosome" generally are higher in female than in male fly embryos during early development.

At the GSA Drosophila Research Conference, Drs. Vicoso and Bachtrog will present evidence of many reversals of sex chromosome to autosome in flies. They identified nine independently evolved sex chromosomes in a wider variety of species than had previously been examined and determined that these newly formed X-chromosomes have become dosage compensated, to balance the relative gene expression between males and females.

Drs. Bachtrog and Vicoso also found evidence of female-biased expression of these chromosomes in the gonads, as expected if sexual antagonism in the form of opposing selective pressures in males versus females played an important role in shaping the expression of this chromosome.


Abstract title: "Frequent sex chromosome transitions in Dipterans." Beatriz Vicoso, Doris Bachtrog. UC Berkeley, Berkeley, CA.



Founded in 1931, the Genetics Society of America (GSA) is the professional scientific society for genetics researchers and educators. The Society's more than 5,000 members worldwide work to deepen our understanding of the living world by advancing the field of genetics, from the molecular to the population level. GSA promotes research and fosters communication through a number of GSA-­‐sponsored conferences including regular meetings that focus on particular model organisms. GSA publishes two peer-­‐reviewed, peer-­edited scholarly journals: GENETICS, which has published high quality original research across the breadth of the field since 1916, and G3: Genes|Genomes|Genetics, an open-­access journal launched in 2011 to disseminate high quality foundational research in genetics and genomics. The society also has a deep commitment to education and fostering the next generation of scholars in the field. For more information about GSA, please visit Also follow GSA on Facebook at and on Twitter @GeneticsGSA.

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