@article{1513,
  abstract     = {Insects of the order Hemiptera (true bugs) use a wide range of mechanisms of sex determination, including genetic sex determination, paternal genome elimination, and haplodiploidy. Genetic sex determination, the prevalent mode, is generally controlled by a pair of XY sex chromosomes or by an XX/X0 system, but different configurations that include additional sex chromosomes are also present. Although this diversity of sex determining systems has been extensively studied at the cytogenetic level, only the X chromosome of the model pea aphid Acyrthosiphon pisum has been analyzed at the genomic level, and little is known about X chromosome biology in the rest of the order.

In this study, we take advantage of published DNA- and RNA-seq data from three additional Hemiptera species to perform a comparative analysis of the gene content and expression of the X chromosome throughout this clade. We find that, despite showing evidence of dosage compensation, the X chromosomes of these species show female-biased expression, and a deficit of male-biased genes, in direct contrast to the pea aphid X. We further detect an excess of shared gene content between these very distant species, suggesting that despite the diversity of sex determining systems, the same chromosomal element is used as the X throughout a large portion of the order. },
  author       = {Pal, Arka and Vicoso, Beatriz},
  journal      = {Genome Biology and Evolution},
  number       = {12},
  pages        = {3259 -- 3268},
  publisher    = {Oxford University Press},
  title        = {{The X chromosome of hemipteran insects: Conservation, dosage compensation and sex-biased expression}},
  doi          = {10.1093/gbe/evv215},
  volume       = {7},
  year         = {2015},
}

@article{1577,
  abstract     = {Contrary to the pattern seen in mammalian sex chromosomes, where most Y-linked genes have X-linked homologs, the Drosophila X and Y chromosomes appear to be unrelated. Most of the Y-linked genes have autosomal paralogs, so autosome-to-Y transposition must be the main source of Drosophila Y-linked genes. Here we show how these genes were acquired. We found a previously unidentified gene (flagrante delicto Y, FDY) that originated from a recent duplication of the autosomal gene vig2 to the Y chromosome of Drosophila melanogaster. Four contiguous genes were duplicated along with vig2, but they became pseudogenes through the accumulation of deletions and transposable element insertions, whereas FDY remained functional, acquired testis-specific expression, and now accounts for ∼20% of the vig2-like mRNA in testis. FDY is absent in the closest relatives of D. melanogaster, and DNA sequence divergence indicates that the duplication to the Y chromosome occurred ∼2 million years ago. Thus, FDY provides a snapshot of the early stages of the establishment of a Y-linked gene and demonstrates how the Drosophila Y has been accumulating autosomal genes.},
  author       = {Carvalho, Antonio and Vicoso, Beatriz and Russo, Claudia and Swenor, Bonnielin and Clark, Andrew},
  journal      = {PNAS},
  number       = {40},
  pages        = {12450 -- 12455},
  publisher    = {National Academy of Sciences},
  title        = {{Birth of a new gene on the Y chromosome of Drosophila melanogaster}},
  doi          = {10.1073/pnas.1516543112},
  volume       = {112},
  year         = {2015},
}