Marsupial Genome Sequences: Providing Insight into Evolution and Disease

Abstract

Marsupials (metatherians), with their position in vertebrate phylogeny and their unique biological features, have been studied for many years by a dedicated group of researchers, but it has only been since the sequencing of the first marsupial genome that their value has been more widely recognised. We now have genome sequences for three distantly related marsupial species (the grey short-tailed opossum, the tammar wallaby, and Tasmanian devil), with the promise of many more genomes to be sequenced in the near future, making this a particularly exciting time in marsupial genomics. The emergence of a transmissible cancer, which is obliterating the Tasmanian devil population, has increased the importance of obtaining and analysing marsupial genome sequence for understanding such diseases as well as for conservation efforts. In addition, these genome sequences have facilitated studies aimed at answering questions regarding gene and genome evolution and provided insight into the evolution of epigenetic mechanisms. Here I highlight the major advances in our understanding of evolution and disease, facilitated by marsupial genome projects, and speculate on the future contributions to be made by such sequences.

Global DNA Methylation patterns on marsupial and devil facial tumour chromosomes

“…We examined the distribution of DNA cytosine methylation on male and female chromosomes of three distantly related, model marsupial species [ 15 ] using an immunofluorescent staining approach. Methylation status of male tammar wallaby [ 3 ] and male opossum fibroblasts [ 2 ] has previously been determined and were therefore used in this study as controls for the technique.…”

Chromosome Evolution in Marsupials

“…Among even the most distantly related eutherians, gene content and gene order are typically highly conserved, with rodents and cetartiodactyls being exceptions [ 33 , 34 ]. In contrast, gene order on the X chromosome of marsupials is not conserved, with a high degree of rearrangement being observed between opossum, devil and tammar wallaby X chromosomes [ 31 , 35 ]. In rodents and cetartiodactyls, rearrangements of the X chromosome have been proposed to be associated with repetitive and/or duplicated sequences, which may have facilitated rearrangement [ 34 , 36 ].…”

Epigenetics and transcription regulation during eukaryotic diversification: the saga of TFIID

“…Furthermore, Macropus eugenii (wallabies) or Monodelphis domestica (opossums) do not have a TAF9 duplication. These two organisms belong to the marsupialia and are the closest relatives of the placentalia (Deakin 2012). Hence, TAF9 was duplicated later than TAF5 and TAF6.…”