Cytogenetic studies have shown that bandicoots (family Peramelidae) eliminate one X chromosome in females and the Y chromosome in males from some somatic tissues at different stages during development. The discovery of a polymorphism for X-linked phosphoglycerate kinase (PGK-1) in a population of Isoodon obesulus from Mount Gambier, South Australia, has allowed us to answer a number of long standing questions relating to the parental source of the eliminated X chromosome, X chromosome inactivation and reactivation in somatic and germ cells of female bandicoots. We have found no evidence of paternal PGK-1 allele expression in a wide range of somatic tissues and cell types from known female heterozygotes. We conclude that paternal X chromosome inactivation occurs in bandicoots as in other marsupial groups and that it is the paternally derived X chromosome that is eliminated from some cell types of females. The absence of PGK-1 paternal activity in somatic cells allowed us to examine the state of X chromosome activity in germ cells. Electrophoresis of germ cells from different aged pouch young heterozygotes showed only maternal allele expression in oogonia whereas an additional paternally derived band was observed in pre-dictyate oocytes. We conclude that reactivation of the inactive X chromosome occurs around the onset of meiosis in female bandicoots. As in other mammals, late replication is a common feature of the Y chromosome in male and the inactive X chromosome in female bandicoots. The basis of sex chromosome loss is still not known; however later timing of DNA synthesis is involved. Our finding that the paternally derived X chromosome is eliminated in females suggests that late DNA replication may provide the imprint for paternal X inactivation and the elimination of sex chromosomes in bandicoots.   

1.
Briscoe DA, Robinson ES, Johnston PG: Glucose-6-phosphate dehydrogenase and lactate dehydrogenase activity in kangaroo and mouse oocytes. Comp Biochem Physiol 75B:685–688 (1983).
2.
Close RL: Sex chromosome mosaicism in liver, thymus, spleen and regenerating liver of Perameles nasuta and Isoodon macrourus. Austral J biol Sci 32:615–624 (1979).
3.
Close RL: Rates of sex chromosome loss during development in different tissues of the bandicoots Perameles nasuta and Isoodon obesulus (Marsupialia: Peramelidae). Austral J biol Sci 37:53–61 (1984).
4.
Close RL, Murray JD, Briscoe DA: Electrophoretic and chromosome surveys of the taxa of short-nosed bandicoots within the genus Isoodon, in Seebeck JH, Brown PR, Wallis RL, Kemper CM (eds): Bandicoots and Bilbies (Surrey Beatty and Sons, Sydney 1990).
5.
Cooper DW, Edwards C, James EA, Sharman GB, VandeBerg JL, Graves JAM: Studies on metatherian sex chromosomes. VI. A third state of an X-linked gene: partial activity for the paternally derived Pgk-A allele in cultured fibroblasts of Macropus giganteus and M. parryi. Austral J biol Sci 30:431–443 (1977).
6.
Cooper DW, Johnston PG, Watson JM, Graves JAM: X-inactivation in marsupials and monotremes. Sem Devel Biol 4:117–128 (1993).
7.
Cooper DW, VandeBerg JL, Sharman GB, Poole WE: Phosphoglycerate kinase polymorphism in kangaroos provides further evidence for paternal X inactivation. Nature New Biol 230:155–157 (1971).
8.
Epstein CJ, Smith S, Travis B, Tucker G: Both X chromosomes function before visible X-chromosome inactivation in female mouse embryos. Nature 274:500–502 (1978).
9.
Gartler SM, Andina R, Gant N: Ontogeny of X chromosome inactivation in the female germ line. Exp Cell Res 91:454–457 (1975).
10.
Hall LS: Growth and a description of the development of external features of pouch young of captive Isoodon macrourus, in Seebeck JH, Brown PR, Wallis RL, Kemper CM (eds): Bandicoots and Bilbies. (Surrey Beatty and Sons, Sydney 1990).
11.
Hayman DL: Marsupial cytogenetics. Austral J Zool 37:331–349 (1990).
12.
Hayman DL, Martin PG: Sex chomosome mosaicism in the marsupial genera Isoodon and Perameles. Genetics 52:1201–1206 (1965).
13.
Hayman DL, Martin PG: Mammalia I: Monotremata and Marsupialia, in John B (ed): Animal Cytogenetics 4: Chordata (Gebruder Borntraeger, Berlin/Stuttgart 1974).
14.
Heath JK: Characterization of a xenogeneic anti-serum raised against the fetal germ cells of the mouse: Cross-reactivity with embryonal carcinoma cells. Cell 15:299–306 (1978).
15.
Johnston PG: X chromosome activity in female germ cells of mice heterozygous for Searle’s translocation T(X;16)16H. Genet Res 37:317–322 (1981).
16.
Johnston PG, Dean D, VandeBerg JL, Robinson ES: HPRT activity in embryos of a South American opossum Monodelphis domestica. Reprod Fertil Dev 6:529–532 (1994).
17.
Johnston PG, Robinson ES: Lack of correlation beween Gpd expression and X chromosome late replication in cultured fibroblasts of the kangaroo Macropus robustus. Austral J biol Sci 39:37–45 (1986).
18.
Johnston PG, Robinson ES, Johnston DM: Dictyate oocytes of a kangaroo (Macropus robustus) show paternal X inactivation at the X-linked Gpd locus. Austral J biol Sci 38:79–84 (1985).
19.
Johnston PG, Sharman GB, James EA, Cooper DW: Studies on metatherian sex chromosomes VII. Glucose-6-phosphate dehydrogenase expression in tissues and cultured fibroblasts of kangaroos. Austral J biol Sci 31:415–424 (1978).
20.
Kratzer PG, Chapman VM: X chromosome reactivation in oocytes of Mus caroli. Proc natl Acad Sci, USA 78:3093–3097 (1981).
21.
Rattazzi MC, Bernini LF, Fiorelli G, Mannucci PM: Electrophoresis of glucose-6-phosphate dehydrogenase: a new technique. Nature 213:79–80 (1967).
22.
Robinson ES, Johnston PG, Sharman GB: X chromosome activity in germ cells of female kangaroos, in Calaby JH, Tyndale-Biscoe CH (eds): Reproduction and Evolution. Proceedings of the 4th Symposium on Comparative Biology of Reproduction, Canberra, Australia (Australian Academy of Science 1977).
23.
Samollow PB, Ford AL, VandeBerg JL: X-linked gene expression in the Virginia opossum: difference between the paternally derived Gpd and Pgk-A loci. Genetics 115:185–195 (1986).
24.
Samollow PB, Johnston PG, Ford AL, VandeBerg JL: X linked gene expression in cultured fibroblasts: evidence from the Gpd and Pgk-A loci of the Virginia opossum and the red-necked wallaby. Biochem Genet 27:313–320 (1989).
25.
Sharman GB: Late DNA replication in the paternally derived X chromosome of female kangaroos. Nature 230:231–232 (1971).
26.
Ullmann SL: Ovary development in bandicoots: sexual differentiation to follicle formation. J Anat 165:45–60 (1989).
27.
VandeBerg JL, Cooper DW, Sharman GB: Studies on metatherian sex chromosomes V. Activity of the paternally derived allele at the X linked Pgk-A locus in some tissues of the kangaroos Macropus giganteus and Macropus parryi. Austral J biol Sci 30:421–430 (1977).
28.
Watson CM, Margan SH, Johnston PG: Sex-chromosome elimination in the bandicoot Isoodon macrourus using Y-linked markers. Cytogenet Cell Genet 81:54–59 (1998).
29.
Watson D, Jacombs AS, Loebel DA, Robinson ES, Johnston PG: Single nucleotide primer extension (SNuPE) analysis of the G6PD gene in somatic cells and oocytes of a kangaroo (Macropus robustus). Genet Res 75:269–274 (2000).
30.
Zenger KR, McKenzie LM, Cooper DW: The first comprehensive genetic linkage map of a marsupial: the tammar wallaby (Macropus eugenii). Genetics 162:321–330 (2002).
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.