title: Karyotypic variation in the Andean rodent Phyllotisxanthopygus (Waterhouse, 1837) (Rodentia, Cricetidae, Sigmodontinae).
abstract: Phyllotisxanthopygus (Waterhouse, 1837) is an Andean rodent endemic to South America. Despite its wide geographical distribution in Argentina, few individuals have been studied on the cytogenetic level and only through conventional staining. In this work, chromosome characterization of Argentine samples of this species was performed using solid staining, C-banding and base-specific fluorochromes. Twenty two specimens were analyzed, collected in the provinces of Jujuy, Catamarca, and the north and south of Mendoza. All studied specimens showed 2n=38, having mostly the bi-armed autosomes, metacentric or submetacentric. Fundamental Number varied between 70 and 72. These changes were due to the presence of chromosome heteromorphisms in individuals from southern Mendoza and Jujuy. C-banding revealed pericentromeric blocks of constitutive heterochromatin in most chromosomes. Acrocentric chromosomes involved in heteromorphisms showed high variation in the amount of heterochromatin within and among populations. Additionally, banding with fluorochromes (DAPI and chromomycin A3) revealed homologous localization of AT and GC rich regions among chromosomes of the different populations analyzed. Comparisons among heteromorphic pairs suggested, however, that the variation might be the result of complex chromosome rearrangements, involving possibly amplifications and/or deletions of heterochromatic segments. These results are in accordance with molecular studies that indicate genetic variability within and among the populations of this taxon.
authors.affiliation: Laboratorio de Genética Evolutiva, IBS (CONICET-UNaM), Félix de Azara 1552, CP3300 Posadas, Misiones, Argentina.
authors.forename: Carolina Alicia
authors.initials: CA
authors.lastname: Labaroni
authors.affiliation: Laboratorio de Genética Evolutiva, IBS (CONICET-UNaM), Félix de Azara 1552, CP3300 Posadas, Misiones, Argentina.
authors.forename: Matías Maximiliano
authors.initials: MM
authors.lastname: Malleret
authors.affiliation: Grupo de Investigaciones de la Biodiversidad (GiB), IADIZA, CONICET, CCT-Mendoza, CC 507, CP5500 Mendoza, Argentina, Instituto Argentino de Zonas Áridas.
authors.forename: Agustina
authors.initials: A
authors.lastname: Novillo
authors.affiliation: Grupo de Investigaciones de la Biodiversidad (GiB), IADIZA, CONICET, CCT-Mendoza, CC 507, CP5500 Mendoza, Argentina, Instituto Argentino de Zonas Áridas.
authors.forename: Agustina
authors.initials: A
authors.lastname: Ojeda
authors.affiliation: Grupo de Investigaciones de la Biodiversidad (GiB), IADIZA, CONICET, CCT-Mendoza, CC 507, CP5500 Mendoza, Argentina, Instituto Argentino de Zonas Áridas.
authors.forename: Daniela
authors.initials: D
authors.lastname: Rodriguez
authors.affiliation: Grupo de Investigaciones de la Biodiversidad (GiB), IADIZA, CONICET, CCT-Mendoza, CC 507, CP5500 Mendoza, Argentina, Instituto Argentino de Zonas Áridas.
authors.forename: Pablo
authors.initials: P
authors.lastname: Cuello
authors.affiliation: Grupo de Investigaciones de la Biodiversidad (GiB), IADIZA, CONICET, CCT-Mendoza, CC 507, CP5500 Mendoza, Argentina, Instituto Argentino de Zonas Áridas.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Ojeda
authors.affiliation: Laboratorio de Genética Evolutiva, IBS (CONICET-UNaM), Félix de Azara 1552, CP3300 Posadas, Misiones, Argentina.
authors.lastname: Dardo Martí
authors.affiliation: Laboratorio de Genética Evolutiva, IBS (CONICET-UNaM), Félix de Azara 1552, CP3300 Posadas, Misiones, Argentina ; Grupo de Investigaciones de la Biodiversidad (GiB), IADIZA, CONICET, CCT-Mendoza, CC 507, CP5500 Mendoza, Argentina, Instituto Argentino de Zonas Áridas.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Lanzone
keywords: Chromosomes; constitutive heterochromatin; fluorochromes; genetic variability; mammals