Deciphering neo-sex and B chromosome evolution by the draft genome of Drosophila albomicans Journal Article

Author(s): Zhou, Qi; Zhu, Hongmei; Huang, Quanfei; Zhao, Li; Zhang, Guo J; Roy, Scott W; Vicoso, Beatriz; Xuan, Zhaolin; Ruan, Jue; Zhang, Yue; Zhao, Ruoping; Ye, Chen; Zhang, Xiuqing; Wang, Jùn; Wang, Wen; Bachtrog, Doris
Article Title: Deciphering neo-sex and B chromosome evolution by the draft genome of Drosophila albomicans
Abstract: Background: Drosophila albomicans is a unique model organism for studying both sex chromosome and B chromosome evolution. A pair of its autosomes comprising roughly 40% of the whole genome has fused to the ancient X and Y chromosomes only about 0.12 million years ago, thereby creating the youngest and most gene-rich neo-sex system reported to date. This species also possesses recently derived B chromosomes that show non-Mendelian inheritance and significantly influence fertility.Methods: We sequenced male flies with B chromosomes at 124.5-fold genome coverage using next-generation sequencing. To characterize neo-Y specific changes and B chromosome sequences, we also sequenced inbred female flies derived from the same strain but without B's at 28.5-fold.Results: We assembled a female genome and placed 53% of the sequence and 85% of the annotated proteins into specific chromosomes, by comparison with the 12 Drosophila genomes. Despite its very recent origin, the non-recombining neo-Y chromosome shows various signs of degeneration, including a significant enrichment of non-functional genes compared to the neo-X, and an excess of tandem duplications relative to other chromosomes. We also characterized a B-chromosome linked scaffold that contains an actively transcribed unit and shows sequence similarity to the subcentromeric regions of both the ancient X and the neo-X chromosome.Conclusions: Our results provide novel insights into the very early stages of sex chromosome evolution and B chromosome origination, and suggest an unprecedented connection between the births of these two systems in D. albomicans.
Keywords: B chromosome; Drosophila albomicans; Neo-sex chromosome
Journal Title: BMC Genomics
Volume: 13
Issue 1
ISSN: 1471-2164
Publisher: BioMed Central  
Date Published: 2012-03-22
Start Page: Article number:109
Copyright Statement: CC BY
DOI: 10.1186/1471-2164-13-109
Open access: yes (OA journal)