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- Mikkelsen, Tarjei S, et al.
(författare)
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Genome of the marsupial Monodelphis domestica reveals innovation in non-coding sequences
- 2007
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 447:7141, s. 167-177
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Tidskriftsartikel (refereegranskat)abstract
- We report a high-quality draft of the genome sequence of the grey, short-tailed opossum (Monodelphis domestica). As the first metatherian ('marsupial') species to be sequenced, the opossum provides a unique perspective on the organization and evolution of mammalian genomes. Distinctive features of the opossum chromosomes provide support for recent theories about genome evolution and function, including a strong influence of biased gene conversion on nucleotide sequence composition, and a relationship between chromosomal characteristics and X chromosome inactivation. Comparison of opossum and eutherian genomes also reveals a sharp difference in evolutionary innovation between protein-coding and non-coding functional elements. True innovation in protein-coding genes seems to be relatively rare, with lineage-specific differences being largely due to diversification and rapid turnover in gene families involved in environmental interactions. In contrast, about 20% of eutherian conserved non-coding elements (CNEs) are recent inventions that postdate the divergence of Eutheria and Metatheria. A substantial proportion of these eutherian-specific CNEs arose from sequence inserted by transposable elements, pointing to transposons as a major creative force in the evolution of mammalian gene regulation.
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| 2. |
- Baker, Michelle L, et al.
(författare)
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Analysis of a set of Australian northern brown bandicoot expressed sequence tags with comparison to the genome sequence of the South American grey short tailed opossum
- 2007
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Ingår i: BMC Genomics. - : Springer Science and Business Media LLC. - 1471-2164. ; 8, s. 50-
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Expressed sequence tags (ESTs) have been used for rapid gene discovery in a variety of organisms and provide a valuable resource for whole genome annotation. Although the genome of one marsupial, the opossum Monodelphis domestica, has now been sequenced, no EST datasets have been reported from any marsupial species. In this study we describe an EST dataset from the bandicoot, Isoodon macrourus, providing information on the transcriptional profile of the bandicoot thymus and the opportunity for a genome wide comparison between the bandicoot and opossum, two distantly related marsupial species. RESULTS: A set of 1319 ESTs was generated from sequencing randomly chosen clones from a bandicoot thymus cDNA library. The nucleic acid and deduced amino acid sequences were compared with sequences both in GenBank and the recently completed whole genome sequence of M. domestica. This study provides information on the transcriptional profile of the bandicoot thymus with the identification of genes involved in a broad range of activities including protein metabolism (24%), transcription and/or nucleic acid metabolism (10%), metabolism/energy pathways (9%), immunity (5%), signal transduction (5%), cell growth and maintenance (3%), transport (3%), cell cycle (0.7%) and apoptosis (0.5%) and a proportion of genes whose function is unknown (5.8%). Thirty four percent of the bandicoot ESTs found no match with annotated sequences in any of the public databases. Clustering and assembly of the 1319 bandicoot ESTs resulted in a set of 949 unique sequences of which 375 were unannotated ESTs. Of these, seventy one unannotated ESTs aligned to non-coding regions in the opossum, human, or both genomes, and were identified as strong non-coding RNA candidates. Eighty-four percent of the 949 assembled ESTs aligned with the M. domestica genome sequence indicating a high level of conservation between these two distantly related marsupials. CONCLUSION: This study is among the first reported marsupial EST datasets with a significant inter-species genome comparison between marsupials, providing a valuable resource for transcriptional analyses in marsupials and for future annotation of marsupial whole genome sequences.
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