Deciphering neo-sex and B chromosome evolution by the draft genome of Drosophila albomicans Zhou, Qi Zhu, Hongmei Huang, Quanfei Zhao, Li Zhang, Guo J Roy, Scott W Beatriz Vicoso ; https://orcid.org/0000-0002-4579-8306 Xuan, Zhaolin Ruan, Jue Zhang, Yue Zhao, Ruoping Ye, Chen Zhang, Xiuqing Wang, Jùn Wang, Wen Bachtrog, Doris 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. BioMed Central 2012 info:eu-repo/semantics/article doc-type:Article Article http://purl.org/coar/resource_type/c_2df8fbb1 https://research-explorer.ista.ac.at/record/2073 Zhou Q, Zhu H, Huang Q, et al. Deciphering neo-sex and B chromosome evolution by the draft genome of Drosophila albomicans. <i>BMC Genomics</i>. 2012;13(1). doi:<a href="https://doi.org/10.1186/1471-2164-13-109">10.1186/1471-2164-13-109</a> info:eu-repo/semantics/altIdentifier/doi/10.1186/1471-2164-13-109 https://creativecommons.org/licenses/by/4.0/