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. 2008;9(2):R30.
doi: 10.1186/gb-2008-9-2-r30. Epub 2008 Feb 12.

Genomic degradation of a young Y chromosome in Drosophila miranda

Doris Bachtrog  1 , Emily Hom, Karen M Wong, Xulio Maside, Pieter de Jong
Affiliations

Genomic degradation of a young Y chromosome in Drosophila miranda

Doris Bachtrog et al. Genome Biol. 2008.

Abstract

Background: Y chromosomes are derived from ordinary autosomes and degenerate because of a lack of recombination. Well-studied Y chromosomes only have few of their original genes left and contain little information about their evolutionary origin. Here, we take advantage of the recently formed neo-Y chromosome of Drosophila miranda to study the processes involved in Y degeneration on a genomic scale.

Results: We obtained sequence information from 14 homologous bacterial artificial chromosome (BAC) clones from the neo-X and neo-Y chromosome of D. miranda, encompassing over 2.5 Mb of neo-sex-linked DNA. A large fraction of neo-Y DNA is composed of repetitive and transposable-element-derived DNA (20% of total DNA) relative to their homologous neo-X linked regions (1%). The overlapping regions of the neo-sex linked BAC clones contain 118 gene pairs, half of which are pseudogenized on the neo-Y. Pseudogenes evolve significantly faster on the neo-Y than functional genes, and both functional and non-functional genes show higher rates of protein evolution on the neo-Y relative to their neo-X homologs. No heterogeneity in levels of degeneration was detected among the regions investigated. Functional genes on the neo-Y are under stronger evolutionary constraint on the neo-X, but genes were found to degenerate randomly on the neo-Y with regards to their function or sex-biased expression patterns.

Conclusion: Patterns of genome evolution in D. miranda demonstrate that degeneration of a recently formed Y chromosome can proceed very rapidly, by both an accumulation of repetitive DNA and degeneration of protein-coding genes. Our data support a random model of Y inactivation, with little heterogeneity in degeneration among genomic regions, or between functional classes of genes or genes with sex-biased expression patterns.

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Figures

Figure 1
Figure 1
Schematic overview of the genomic regions investigated on the neo-sex chromosomes, anchored on the D. pseudoobscura genomic annotation. Genes in grey represent pseudogenes on the neo-Y.
See this image and copyright information in PMC

References

    1. Bull JJ. Evolution of Sex Determining Mechanisms. Menlo Park, CA: Benjamin Cummings; 1983.
    1. Charlesworth B. The evolution of chromosomal sex determination and dosage compensation. Curr Biol. 1996;6:149–162. doi: 10.1016/S0960-9822(02)00448-7. - DOI - PubMed
    1. Rice WR. Evolution of the Y sex chromosome in animals. BioScience. 1996;46:331–343. doi: 10.2307/1312947. - DOI
    1. Charlesworth B, Jarne P, Assimacopoulos S. The distribution of transposable elements within and between chromosomes in a population of Drosophila melanogaster. III. Element abundances in heterochromatin. Genet Res. 1994;64:183–197. - PubMed
    1. Skaletsky H, Kuroda-Kawaguchi T, Minx PJ, Cordum HS, Hillier L, Brown LG, Repping S, Pyntikova T, Ali J, Bieri T, Chinwalla A, Delehaunty A, Delehaunty K, Du H, Fewell G, Fulton L, Fulton R, Graves T, Hou SF, Latrielle P, Leonard S, Mardis E, Maupin R, McPherson J, Miner T, Nash W, Nguyen C, Ozersky P, Pepin K, Rock S, et al. The male-specific region of the human Y chromosome is a mosaic of discrete sequence classes. Nature. 2003;423:825–837. doi: 10.1038/nature01722. - DOI - PubMed

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