In the absence of an SRY orthologue the platypus sex determining gene is unknown, so genes in the human testis determining pathway are of particular interest as candidates. SOX9 is an attractive choice because SOX9 deletions cause male-to-female sex reversal in humans and mice, and SOX9 duplications cause female-to-male sex reversal. We have localized platypus SOX9, as well as the related SOX10, to platypus chromosomes 15 and 10, respectively, the first assignments to these platypus chromosomes, and the first comparative mapping markers from human chromosomes 17 and 22. The autosomal localization of platypus SOX9 in this study contradicts the hypothesis that SOX9 acts as the sex determining switch in platypus.

Baumstark A, Akhverdyan M, Schulze A, Reisert I, Vogel W, Just W: Exclusion of SOX9 as the testis determining factor in Ellobius lutescens: evidence for another testis determining gene besides SRY and SOX9. Mol Genet Metab 72:61–66 (2001).
Church GM, Gilbert W: Genomic sequencing. Proc Natl Acad Sci USA 81:1991–1995 (1984).
Foster JW, Dominguez-Steglich MA, Guioli S, Kwok G, Weller PA, et al: Campomelic Dysplasia and autosomal sex reversal caused by mutations in an SRY-related gene. Nature 372:525–530 (1994).
Grützner F, Rens W, Tsend-Ayush E, El-Mogharbel N, O’Brien PCM, et al: In the platypus a meiotic chain of ten sex chromosomes shares genes with the bird Z and mammal X chromosomes. Nature 432:913–917 (2004).
Huang B, Wang S, Ning Y, Lamb AN, Bartley J: Autosomal XX sex reversal caused by duplication of SOX9. Am J Med Genet 87:349–353 (1999).
Kent J, Wheatley SC, Andrews JE, Sinclair AH, Koopman P: A male-specific role for SOX9 in vertebrate sex determination. Development 122:2813–2822 (1996).
Morais da Silva S, Hacker A, Harley V, Goodfellow P, Swain A, Lovell-Badge R: Sox9 expression during gonadal development implies a conserved role for the gene in testis differentiation in mammals and birds. Nat Genet 14:62–68 (1996).
Nanda I, Zend-Ajush E, Shan Z, Grützner F, Schartl M, et al: Conserved synteny between the chicken Z sex chromosome and human chromosome 9 includes the male regulatory gene DMRT1: a comparative (re)view on avian sex determination. Cytogenet Cell Genet 89:67–78 (2000).
Pask AJ: The Evolution of Genes in the Sex Determining Pathway. (LaTrobe University, Melbourne 1999).
Pask AJ, Harry JL, Graves JAM, O’Neill RJ, Layfield SL, et al: SOX9 has both conserved and novel roles in marsupial sexual differentiation. Genesis 33:131–139 (2002).
Pingault V, Bondurand N, Kuhlbrodt K, Goerich DE, Prehu MO, et al: SOX10 mutations in patients with Waardenburg-Hirschsprung disease. Nat Genet 18:171–173 (1998).
Rens W, Grützner F, O’Brien PCM, Fairclough H, Graves JAM, Ferguson-Smith MA: Resolution and evolution of the duck-billed platypus karyotype with an X1Y1X2Y2X3Y3X4Y4X5Y5 male sex chromosome constitution. Proc Natl Acad Sci USA 101:16257–16261 (2004).
Spotila LD, Spotila JR, Hall SE: Sequence and expression analysis of WT1 and Sox9 in the red-eared slider turtle, Trachemys scripta. J Exp Zool 281:417–427 (1998).
van Rheede T, Bastiaans T, Boone DN, Hedges SB, de Jong WW, Madsen O: The platypus is in its place: nuclear genes and indels confirm the sister group relation of monotremes and therians. Mol Biol Evol 23:587–597 (2006).
Wagner T, Wirth J, Meyer J, Zabel B, Held M, et al: Autosomal sex reversal and Campomelic Dysplasia are caused by mutations in and around the SRY-related gene SOX9. Cell 79:1111–1120 (1994).
Western PS, Harry JL, Graves JAM, Sinclair AH: Temperature-dependent sex determination in the American alligator: AMH precedes SOX9 expression. Dev Dyn 216:411–419 (1999).
Wright EM, Snopek B, Koopman P: Seven new members of the Sox gene family expressed during mouse development. Nucleic Acids Res 21:744 (1993).
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.