Karyotype characterization and nucleolar organizer regions of marsupial species (Didelphidae) from areas of Cerrado and Atlantic Forest in Brazil

Genetics and Molecular Biology

Núbia P. Pereira¹  Karen Ventura¹  Magno C. Silva Júnior¹  Daniela De Melo E Silva¹  Yatiyo Yonenaga-yassuda¹  Katia C. M. Pellegrino¹ 

关键词: marsupials;    karyotypes;    cytogenetics;    Didelphidae;    NORs;   

DOI  :  10.1590/S1415-47572008005000012

来源: SciELO

【 摘 要 】

The karyotypes of 23 specimens belonging to 16 species from nine genera of Brazilian marsupials (family Didelphidae) were studied. The animals were collected in eight localities of Cerrado or Atlantic Forest biomes in the states of Goiás, Tocantins and São Paulo. The karyotypes were analyzed after conventional Giemsa staining and silver staining of the nucleolus organizer regions (Ag-NORs). New karyotypic data were obtained forGracilinanus microtarsus(2n = 14, FN = 24), Marmosops paulensis(2n = 14, FN = 24) , Micoreus paraguayanus(2n = 14, FN = 20) andMonodelphis rubida(2n = 18, FN = 32) and are discussed in detail. The karyotypes ofG. microtarsus ,M. paulensisandM. paraguayanusinclude three large pairs of submetacentrics (pairs 1, 2 and 3) and a medium-sized metacentric or submetacentric pair 4. Pairs 5 and 6 are small submetacentrics inG. microtarsusandM. paulensisand acrocentrics inM. paraguayanus .M. paulensispresented a single Ag-NOR in pair 6 (6p6p), whileM. paraguayanusexhibited multiple Ag-NORs in pairs 5 and 6 (5pq5pq6p6p). There was variation in size and morphology of the sex chromosomes among these species.Monodelphis rubidapresented a karyotype with 2n = 18 and FN = 32 composed of a large submetacentric pair 1, a medium-sized metacentric pair 2 and six pairs of submetacentrics (pairs 3 through 8). The X was a small acrocentric and the Y was dot-like. A single Ag-NOR bearing pair (5p5p) characterizedM. rubida.Relevant karyotypic information was obtained for 19 specimens belonging to 12 species collected in areas sampled for the first time [ Caluromys lanatusandC. philander(2n = 14, FN = 20),Gracilinanus emiliae(2n = 14, FN = 24),Marmosa murina ,Metachirus nudicaudatusandMicoureus demerarae(2n = 14, FN = 20),Monodelphis americana(2n = 18, FN = 32) andM. domestica(2n = 18, FN = 20), andDidelphis marsupialis, Philander frenata, P. opossumandP.sp (2n = 22, FN = 20)]. Although the karyotypes were relatively conserved with respect to the morphology of the autosomes among species with the same diploid number, some differences regarding FN, sex chromosomes morphology and Ag-NORs patterns were detected.

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