The Chinese soft-shelled turtle (Pelodiscus sinensis, Trionychidae, Testudines) has ZZ/ZW-type micro-sex chromosomes where the 18S-28S ribosomal RNA genes (18S-28S rDNA) are located. The W chromosome is morphologically differentiated from the Z chromosome by partial deletion and amplification of 18S-28S rDNA and W-specific repetitive sequences. We recently found a functional gene (TOP3B) mapped on the P. sinensis Z chromosome, which is located on chicken (Gallus gallus, GGA) chromosome 15. Then we cloned turtle homologues of 4 other GGA15-linked genes (GIT2, NF2, SBNO1, SF3A1) and localized them to P. sinensis chromosomes. The 4 genes all mapped on the Z chromosome, and 2 of them (SBNO1, SF3A1) were also localized to the W chromosome. Our mapping data suggest that at least one large inversion occurred between GGA15 and the P. sinensis Z chromosome, and that there are homologous regions in the distal portions of both the short and long arms between the Z and W chromosomes. W chromosomal differentiation in P. sinensis probably proceeded by the deletion of the proximal chromosomal region followed by 18S-28S rDNA amplification, after a paracentric inversion occurred at the breakpoints between the distal region of 18S-28S rDNA and the proximal region of SBNO1 on the Z chromosome.

Benton MJ, Donoghue PCJ: Paleontological evidence to date the tree of life. Mol Biol Evol 24:26–53 (2007).
Bourque G, Zdobnov EM, Bork P, Pevzner PA, Tesler G: Comparative architectures of mammalian and chicken genomes reveal highly variable rates of genomic rearrangements across different lineages. Genome Res 15:98–110 (2005).
Burt DW, Bruley C, Dunn IC, Jones CT, Ramage A, et al: The dynamics of chromosome evolution in birds and mammals. Nature 402:411–413 (1999).
de Oliveira EHC, Habermann FA, Lacerda O, Sbalqueiro IJ, Wienberg J, Müller S: Chromosome reshuffling in birds of prey: the karyotype of the world’s largest eagle (Harpy eagle, Harpia harpyja) compared to that of the chicken (Gallus gallus). Chromosoma 114:338–343 (2005).
Ezaz T, Quinn AE, Miura I, Sarre SD, Georges A, Graves JAM: The dragon lizard Pogona vitticeps has ZZ/ZW micro-sex chromosomes. Chromosome Res 13:763–776 (2005).
Ezaz T, Valenzuela N, Grützner F, Miura I, Georges A, et al: An XX/XY sex microchromosome system in a freshwater turtle, Chelodina longicollis (Testudines: Chelidae) with genetic sex determination. Chromosome Res 14:139–150 (2006).
Guttenbach M, Nanda I, Feichtinger W, Masabanda JS, Griffin DK, Schmid M: Comparative chromosome painting of chicken autosomal paints 1–9 in nine different bird species. Cytogenet Genome Res 103:173–184 (2003).
Howell WM, Black DA: Controlled silver-staining of nucleolus organizer regions with a protective colloidal developer: a 1-step method. Experientia 36:1014–1015 (1980).
International Chicken Genome Sequencing Consortium: Sequence and comparative analysis of the chicken genome provide unique perspectives on vertebrate evolution. Nature 432:695–716 (2004).
Iwabe N, Hara Y, Kumazawa Y, Shibamoto K, Saito Y, et al: Sister group relationship of turtles to the bird-crocodilian clade revealed by nuclear DNA-coded proteins. Mol Biol Evol 22:810–813 (2005).
Janke A, Erpenbeck D, Nilsson M, Arnason U: The mitochondrial genomes of the iguana (Iguana iguana) and the caiman (Caiman crocodylus): implications for amniote phylogeny. Proc R Soc Lond B 268:623–631 (2001).
Jennen DG, Crooijmans RPMA, Kamps B, Açar R, van der Poel JJ, Groenen MAM: Comparative map between chicken Chromosome 15 and human chromosomal region 12q24 and 22q11–q12. Mamm Genome 14:629–639 (2003).
Kawai A, Nishida-Umehara C, Ishijima J, Tsuda Y, Ota H, Matsuda Y: Different origins of bird and reptile sex chromosomes inferred from comparative mapping of chicken Z-linked genes. Cytogenet Genome Res 117:92–102 (2007).
Kawai A, Ishijima J, Nishida C, Kosaka A, Ota H, et al: The ZW sex chromosomes of Gekko hokouensis (Gekkonidae, Squamata) represent highly conserved homology with those of avian species. Chromosoma 118:43–51 (2009).
Kumar S, Hedges SB: A molecular timescale for vertebrate evolution. Nature 392:917–920 (1998).
Kumazawa Y: Mitochondrial genomes from major lizard families suggest their phylogenetic relationships and ancient radiations. Gene 388:19–26 (2007).
Kumazawa Y, Nishida M: Complete mitochondrial DNA sequences of the green turtle and blue-tailed mole skink: statistical evidence for Archosaurian affinity of turtles. Mol Biol Evol 16:784–792 (1999).
Matsubara K, Tarui H, Toriba M, Yamada K, Nishida-Umehara C, et al: Evidence for different origin of sex chromosomes in snakes, birds, and mammals and step-wise differentiation of snake sex chromosomes. Proc Natl Acad Sci USA 103:18190–18195 (2006).
Matsuda Y, Chapman VM: Application of fluorescence in situ hybridization in genome analysis of the mouse. Electrophoresis 16:261–272 (1995).
Matsuda Y, Nishida-Umehara C, Tarui H, Kuroiwa A, Yamada K, et al: Highly conserved linkage homology between birds and turtles: Bird and turtle chromosomes are precise counterparts of each other. Chromosome Res 13:601–615 (2005).
Nanda I, Shan Z, Schartl M, Burt DW, Koehler M, et al: 300 million years of conserved synteny between chicken Z and human chromosome 9. Nat Genet 21:258–259 (1999).
Nanda I, Haaf T, Schartl M, Schmid M, Burt DW: Comparative mapping of Z-orthologous genes in vertebrates: implications for the evolution of avian sex chromosomes. Cytogenet Genome Res 99:178–184 (2002).
Nishida C, Ishijima J, Kosaka A, Tanabe H, Habermann FA, et al: Characterization of chromosome structures of Falconinae (Falconidae, Falconiformes, Aves) by chromosome painting and delineation of chromosome rearrangements during their differentiation. Chromosome Res 16:171–181 (2008).
Nishida-Umehara C, Tsuda Y, Ishijima J, Ando J, Fujiwara A, et al: The molecular basis of chromosome orthologies and sex chromosomal differentiation in palaeognathous birds. Chromosome Res 15:721–734 (2007).
Ohno S: Sex Chromosomes and Sex-Linked Genes (Springer, Berlin 1967).
Olmo E, Signorino G: Chromorep: a reptile chromosomes database. Internet references. Retrieved from: (2005).
Parma P, Radi O, Vidal V, Chaboissier MC, Dellambra E, et al: R-spondin1 is essential in sex determination, skin differentiation and malignancy. Nat Genet 38:1304–1309 (2006).
Rest JS, Ast JC, Austin CC, Waddell PJ, Tibbetts EA, et al: Molecular systematics of primary reptilian lineages and the tuatara mitochondrial genome. Mol Phylogent Evol 29:289–297 (2003).
Sarre SD, Georges A, Quinn A: The ends of a continuum: genetic and temperature-dependent sex determination in reptiles. BioEssays 26:639–645 (2004).
Schmid M, Nanda I, Hoehn H, Schartl M, Haaf T, et al: Second report on chicken genes and chromosomes 2005. Cytogenet Genome Res 109:415–479 (2005).
Smith CA, Shoemaker CM, Roeszler KN, Queen J, Crews D, Sinclair AH: Cloning and expression of R-SpondinI in different vertebrates suggests a conserved role in ovarian development. BMC Dev Biol 8:72 (2008).
Tomizuka K, Horikoshi K, Kitada R, Sugawara Y, Iba Y, et al: R-spondin1 plays an essential role in ovarian development through positively regulating Wnt-4 signaling. Hum Mol Genet 17:1278–1291 (2008).
Valenzuela N, Lance VA: Temperature-Dependent Sex Determination in Vertebrates. (Smithonian Books, Washington DC 2004).
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.