title: Mapping the distribution of the telomeric sequence (T2AG3)n in the 2n = 14 ancestral marsupial complement and in the macropodines (Marsupialia: Macropodidae) by fluorescence in situ hybridization.
abstract: In this study we test the theory that the presence of the conserved vertebrate telomeric sequence (T(2)AG(3))(n) at the centromeres of Australian marsupial 2n = 14 complements is evidence that these karyotypes are recently derived, which is contrary to the generally held view that the 2n = 14 karyotype is ancestral for Australasian and American marsupials. Here we compare the distribution of the (T(2)AG(3))( n ) sequence and constitutive heterochromatin in the presumed ancestral 2n = 14 complement and in complements with known rearrangements. We found that where there were moderate to large amounts of constitutive heterochromatin, the distribution of the (T(2)AG(3))(n) sequence reflected its presence as a native component of satellite DNA rather than its involvement in past rearrangements. The presence of centromeric heterochromatin in all Australian 2n = 14 complements therefore suggests that centromeric sites of the (T(2)AG(3))(n) sequence do not represent evidence for recent rearrangements.
authors.affiliation: Department of Biological Sciences, Macquarie University, New South Wales 2109, Australia.
authors.forename: C J
authors.initials: CJ
authors.lastname: Metcalfe
authors.forename: M D B
authors.initials: MD
authors.lastname: Eldridge
authors.forename: P G
authors.initials: PG
authors.lastname: Johnston
mesh_terms: D000818:Animals; D020223:Chromosome Painting; D015321:Gene Rearrangement / Q000235:genetics; D007614:Macropodidae / Q000235:genetics*; D018598:Minisatellite Repeats / Q000235:genetics*; D013045:Species Specificity; D016615:Telomere / Q000235:genetics*