XY and ZW: Is Meiotic Sex Chromosome Inactivation the Rule in Evolution?

Howard Hughes Medical Institute, Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA.
PLoS Genetics (Impact Factor: 8.17). 06/2009; 5(5):e1000493. DOI: 10.1371/journal.pgen.1000493
Source: PubMed
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: How introns are lost from eukaryotic genomes during evolution remains an enigmatic question in biology. By comparative genome analysis of five Caenorhabditis and eight Drosophila species, we found that the likelihood of intron loss is highly influenced by the degree of sequence homology at exon-intron junctions: a significant elevated degree of microhomology was observed for sequences immediately flanking those introns that were eliminated from the genome of one or more sub-species. This determinant was significant even at individual nucleotides. We propose that microhomology-mediated DNA repair underlies this phenomenon which we termed microhomology-mediated intron loss (MMIL). This hypothesis is further supported by the observations that in both species i) smaller introns are preferentially lost over longer ones and ii) genes that are highly transcribed in germ cells, and are thus more prone to DNA double strand breaks, display elevated frequencies of intron loss. Our data also testify against a prominent role for reverse transcriptase-mediated intron loss (RTMIL) in metazoans.
    Genome Biology and Evolution 06/2013; 5(6). DOI:10.1093/gbe/evt088 · 4.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Sex chromosome drivers are selfish elements that subvert Mendel's first law of segregation and therefore are overrepresented among the products of meiosis. The sex-biased progeny produced then fuels an extended genetic conflict between the driver and the rest of the genome. Many examples of sex chromosome drive are known, but the occurrence of this phenomenon is probably largely underestimated because of the difficulty to detect it. Remarkably, nearly all sex chromosome drivers are found in two clades, Rodentia and Diptera. Although very little is known about the molecular and cellular mechanisms of drive, epigenetic processes such as chromatin regulation could be involved in many instances. Yet, its evolutionary consequences are far-reaching, from the evolution of mating systems and sex determination to the emergence of new species. Copyright © 2014 Cold Spring Harbor Laboratory Press; all rights reserved.
    Cold Spring Harbor perspectives in biology 12/2014; DOI:10.1101/cshperspect.a017616 · 8.23 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The causes of the large effect of the X chromosome in reproductive isolation and speciation have long been debated. Charlesworth et al. (1987) demonstrated that X-linked loci are expected to have higher rates of adaptive evolution than autosomal loci if new beneficial mutations are on average recessive. Reproductive isolation should therefore evolve faster when contributing loci are located on the X chromosome (the faster-X hypothesis). In this study, we have analysed genome-wide nucleotide polymorphism data from the house mouse subspecies Mus musculus castaneus and nucleotide divergence from Mus famulus and Rattus norvegicus to compare rates of adaptive evolution for autosomal and X-linked protein-coding genes. We found significantly faster adaptive evolution for X-linked loci, particularly for genes with expression in male-specific tissues, but autosomal and X-linked genes with expression in female-specific tissues evolve at similar rates. We also estimated rates of adaptive evolution for genes expressed during spermatogenesis, and found that X-linked genes that escape meiotic sex chromosome inactivation (MSCI) show rapid adaptive evolution. Our results suggest that faster-X adaptive evolution is either due to net recessivity of new advantageous mutations or due to a special gene content of the X chromosome which regulates male function and spermatogenesis. We discuss how our results help to explain the large effect of the X chromosome in speciation.
    Genetics 12/2013; 196(4). DOI:10.1534/genetics.113.158246 · 4.87 Impact Factor

Preview (2 Sources)

1 Download
Available from