Poster Presentation Society for Molecular Biology and Evolution Conference 2016

Testing the parent-of-origin hypothesis in dasyurid telomere length dimorphism (#573)

Emory Ingles 1 , Janine Deakin 1
  1. Institute for Applied Ecology, University of Canberra, Canberra, ACT, Australia

The marsupial family Dasyuridae is characterised by an unusual and non-random pattern of telomere length distributions. On any given chromosome pair, one homologue will have short and the other long telomeres. In males, it is always the Y chromosome that has long telomeres, leading to the hypothesis that the distribution of telomere length is based on parental origin of chromosomes (the parent-of-origin hypothesis). This project aims to test this hypothesis, in particular using Tasmanian devils, antechinus, quoll and dunnart species. Because marsupials inactivate the paternally-derived X chromosome in females as part of a dosage compensation mechanism, it is possible to identify the parent origin of sex chromosomes in females using epigenetic immunofluorescence. Specifically, the maternally-derived active X is hypermethylated, the paternally-derived inactive X hypomethylated, and there is differential staining of the histone active marks H3K9ac, H4Kac, H3K4me2 between the active and inactive X chromosomes. In conjunction with telomere quantitative fluorescence in situ hybridisation (qFISH) to determine telomere length at the chromosome level, this will allow us to test if telomere length is correlated with chromosome parent origin in female individuals. Preliminary results for methylation staining on devil and quoll support the parent-of-origin hypothesis, with the paternally derived, hypomethylated X being the homologue with long telomeres. To test for any male specific telomere elongation prior to fertilisation, telomere qFISH will further be used to investigate changes in telomere length throughout the male germ line, as well as in sperm. Taken together, these experiments will provide insight into the workings and regulation of telomere length dimorphism in dasyurid species.