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ABSTRACT |
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| Localization of chromosome regions in potoroo nuclei (Potorous tridactylus Marsupialia: Potoroinae) | |||
| W.Rens 1, P.C.M. O’Brien 1, J.A.M. Graves 2, M.A. Ferguson-Smith 1 | |||
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1 Centre for Veterinary Science, Dept of Clinical Veterinary Medicine, University of Cambridge, Cambridge CB3 OES, UK 2 Comparative Genomics Research Group, Research School of Biological Sciences, The Australian National University, Canberra, ACT 2601, Australia |
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Chromosome regions of the long-nosed potoroo (Potorous tridactylus, 2n=12female,13male)) were localized in 3D-preserved nuclei of the potoroo to test the hypothesis that marsupial chromosomes have a radial distribution rather than a Rabl configuration. Chromosome paints of the rat kangaroo (Aepyprymnus rufuscens, 2n=32) were used to define the chromosome regions in the long nosed potoroo karyotype. In human nuclei chromosomes are distributed in a proposed radial fashion. Gene-rich chromosomes in the human interphase nucleus are preferentially located in the central area while gene-poor chromosomes are found more at the periphery of the nucleus; this feature is conserved in primates and chicken. The functional organization of marsupial cell nuclei are of interest, firstly because marsupials form an excellent outgroup for mammalian species and, secondly because most marsupials have a small number of chromosomes. For these karyotypes, gene content might be less a determining factor in chro mosome localization than for instance chromosome size and centromere position. Marsupials diverged 160 million years ago from other Mammalian species and apart from the monotremes (platypus and echidna) no other mammalian species diverged this early. Chromosome ordering in nuclei of Potorous tridactylus is related to their size and centromere position. Replication labeling by the incorporation of halogenated deoxyuridines was performed to determine the relationship between replication patterns and chromosome localization. In addition it was observed that the nucleus was not a smooth entity but had projections occupied by specific chromosome regions. Human nuclei can also show projections but they are only observed in malignancies. In plants an impact on fertility and survival was reported recently when similar projections were induced.
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Abstracts will be published by Elsevier (Annales de Génétique) |
