Physical map of two tammar wallaby chromosomes: a strategy for mapping in non-model mammals.
Marsupials are especially valuable for comparative genomic studies of mammals. Two distantly related model marsupials have been sequenced: the South American opossum (Monodelphis domestica) and the tammar wallaby (Macropus eugenii), which last shared a common ancestor about 70 Mya. The six-fold opossum genome sequence has been assembled and assigned to chromosomes with the help of a cytogenetic map. A good cytogenetic map will be even more essential for assembly and anchoring of the two-fold wallaby genome. As a start to generating a physical map of gene locations on wallaby chromosomes, we focused on two chromosomes sharing homology with the human X, wallaby chromosomes X and 5. We devised an efficient strategy for mapping large conserved synteny blocks in non-model mammals, and applied this to generate dense maps of the X and 'neo-X' regions and to determine the arrangement of large conserved synteny blocks on chromosome 5. Comparisons between the wallaby and opossum chromosome maps revealed many rearrangements, highlighting the need for comparative gene mapping between South American and Australian marsupials. Frequent rearrangement of the X, along with the absence of a marsupial XIST gene, suggests that inactivation of the marsupial X chromosome does not depend on a whole-chromosome repression by a control locus.
Deakin
Janine E
JE
ARC Centre of Excellence for Kangaroo Genomics, Research School of Biological Sciences, The Australian National University, Canberra, ACT 0200, Australia. Janine.Deakin@anu.edu.au
Koina
Edda
E
Waters
Paul D
PD
Doherty
Ruth
R
Patel
Vidushi S
VS
Delbridge
Margaret L
ML
Dobson
Bianca
B
Fong
James
J
Hu
Yanqiu
Y
van den Hurk
Cecilia
C
Pask
Andrew J
AJ
Shaw
Geoff
G
Smith
Carly
C
Thompson
Katherine
K
Wakefield
Matthew J
MJ
Yu
Hongshi
H
Renfree
Marilyn B
MB
Graves
Jennifer A Marshall
JA
D000818:Animals; D001483:Base Sequence; D033481:Chromosomes, Mammalian / Q000235:genetics*; D017931:DNA Primers / Q000235:genetics; D017404:In Situ Hybridization, Fluorescence; D007614:Macropodidae / Q000235:genetics*; D015335:Molecular Probes / Q000235:genetics; D008969:Molecular Sequence Data; D020161:Physical Chromosome Mapping / Q000379:methods*; D017422:Sequence Analysis, DNA; D026801:Synteny / Q000235:genetics; D014960:X Chromosome / Q000235:genetics*; D049951:X Chromosome Inactivation / Q000235:genetics*
D017931:DNA Primers; D015335:Molecular Probes