Chromosome Research

, Volume 14, Issue 2, pp 139–150

An XX/XY sex microchromosome system in a freshwater turtle, Chelodina longicollis (Testudines: Chelidae) with genetic sex determination

Authors

    • Comparative Genomics Group, Research School of Biological SciencesThe Australian National University
  • Nicole Valenzuela
    • Department of Ecology, Evolution, and Organismal BiologyIowa State University
  • Frank Grützner
    • Comparative Genomics Group, Research School of Biological SciencesThe Australian National University
  • Ikuo Miura
    • Institute for Amphibian Biology, Graduate School of ScienceHiroshima University
  • Arthur Georges
    • Institute for Applied EcologyUniversity of Canberra
  • Russell L. Burke
    • Department of BiologyHofstra University
  • Jennifer A. Marshall Graves
    • Comparative Genomics Group, Research School of Biological SciencesThe Australian National University
Article

DOI: 10.1007/s10577-006-1029-6

Cite this article as:
Ezaz, T., Valenzuela, N., Grützner, F. et al. Chromosome Res (2006) 14: 139. doi:10.1007/s10577-006-1029-6

Abstract

Heteromorphic sex chromosomes are rare in turtles, having been described in only four species. Like many turtle species, the Australian freshwater turtle Chelodina longicollis has genetic sex determination, but no distinguishable (heteromorphic) sex chromosomes were identified in a previous karyotyping study. We used comparative genomic hybridization (CGH) to show that C. longicollis has an XX/XY system of chromosomal sex determination, involving a pair of microchromosomes. C-banding and reverse fluorescent staining also distinguished microchromosomes with different banding patterns in males and females in ∼70% cells examined. GTG-banding did not reveal any heteromorphic chromosomes, and no replication asynchrony on the X or Y microchromosomes was observed using replication banding. We conclude that there is a very small sequence difference between X and Y chromosomes in this species, a difference that is consistently detectable only by high-resolution molecular cytogenetic techniques, such as CGH. This is the first time a pair of microchromosomes has been identified as the sex chromosomes in a turtle species.

Key words

CGHChelodina longicolliscomparative genomic hybridizationeastern snake-necked turtlemicrochromosomessex chromosomes

Copyright information

© Springer 2006