Cytogenetic analysis of Phyllomedusa distincta Lutz, 1950 (2n = 2x = 26), P. tetraploidea Pombal and Haddad, 1992 (2n = 4x = 52), and their natural triploid hybrids (2n = 3x = 39) (Anura, Hylidae, Phyllomedusinae)

Background: Natural polyploidy has played an important role during the speciation and evolution of vertebrates, including anurans, with more than 55 described cases. The species of the Phyllomedusa burmeisteri group are mostly characterized by having 26 chromosomes, but a karyotype with 52 chromosomes was described in P. tetraploidea. This species was found in sintopy with P. distincta in two localities of São Paulo State (Brazil), where triploid animals also occur, as consequence of natural hybridisation. We analyse the chromosomes of P. distincta, P. tetraploidea, and their triploid hybrids, to enlighten the origin of polyploidy and to obtain some evidence on diploidisation of tetraploid karyotype.Results: Phyllomedusa distincta was 2n = 2x = 26, whereas P. tetraploidea was 2n = 4x = 52, and the hybrid individuals was 2n = 3x = 39. In meiotic phases, bivalents were observed in the diploid males, whereas both bivalents and tetravalents were observed in the tetraploid males. Univalents, bivalents or trivalents; metaphase II cells carrying variable number of chromosomes; and spermatids were detected in the testis preparations of the triploid males, indicating that the triploids were not completely sterile. In natural and experimental conditions, the triploids cross with the parental species, producing abnormal egg clutches and tadpoles with malformations. The embryos and tadpoles exhibited intraindividual karyotype variability and all of the metaphases contained abnormal constitutions. Multiple NORs, detected by Ag-impregnation and FISH with an rDNA probe, were observed on chromosome 1 in the three karyotypic forms; and, additionally, on chromosome 9 in the diploids, mostly on chromosome 8 in the tetraploids, and on both chromosome 8 and 9 in the triploids. Nevertheless, NOR-bearing chromosome 9 was detected in the tetraploids, and chromosome 9 carried active or inactive NORs in the triploids. C-banding, base-specific fluorochrome stainings with CMA3 and DAPI, FISH with a telomeric probe, and BrdU incorporation in DNA showed nearly equivalent patterns in the karyotypes of P. distincta, P. tetraploidea, and the triploid hybrids.Conclusions: All the used cytogenetic techniques have provided strong evidence that the process of diploidisation, an essential step for stabilising the selective advantages produced by polyploidisation, is under way in distinct quartets of the tetraploid karyotype. © 2013 Gruber et al.; licensee BioMed Central Ltd.

Pico e flutuação da pressão intra-ocular: comparação entre curva tensional diária e teste de sobrecarga hídrica e comparação entre 2 testes de sobrecarga hídrica em horários diferentes

Pós-graduação em Bases Gerais da Cirurgia - FMB

ECLAC Notes Nº 39

Foreign Direct Investment Rose 44% in 2004 Integration In South America's Natural Gas Industry Opinion by José Luis Machinea: Foreign Direct Investment in Latin America: the Need to Sustain the Past Year's Recovery and Achieve Greater Benefits Highlights: Development Banks and Financing for Productive Development Indicators Poverty and Precarious Housing in Latin American Cities Recent Titles Calendar

Notas de la CEPAL Nº 39

Aumenta un 44% inversión extranjera directa (IED)en 2004 Integración en la industria del gas natural en América del Sur Columna de opinión de José Luis Machinea. IED en América Latina: la necesidad de sostener la recuperación del último año y lograr mayores beneficios Precisiones: La banca de desarrollo y el financiamiento productivo Indicadores Pobreza y precariedad habitacional en las ciudades de América Latina Publicaciones Recientes Calendario de Eventos

Carta Circular de la Red de Cooperación en la Gestión Integral de Recursos Hídricos para el Desarrollo Sustentable en América Latina y el Caribe N° 39

Editorial.-- Discusión abierta: Políticas tarifarias para el logro de los ODM ; Recursos naturales en UNASUR ; El derecho humano al agua y al saneamiento.-- Reuniones: Políticas Tarifarias y Regulatorias ; Cooperación en Aguas Transfronterizas ; Latinosan III.-- Noticias en la RED: Estrategia Nacional de Recursos Hídricos ; Desarrollo hidroeléctrico en Chile.-- Noticias sobre Internet y WWW

Notas de Población Vol.39 N° 95

Incluye bibliografía

Network for Cooperation in Integrated Water Resource Management for Sustainable Development in Latin America and the Caribbean No. 39

Editorial remarks.-- Open discussion: Tariff policies for the achievement of MDGs ; Natural resources within UNASUR ; The human right to water and sanitation.-- Meetings: Tariff and Regulatory Policies ; Transboundary Water Cooperation ; Latinosan III.-- News of the Network: National Water Resources Strategy ; Hydroelectric Development in Chile.-- Internet and WWW News

U-Pb SHRIMP and 40Ar/39Ar constraints on the timing of mineralization in the Paleoproterozoic Caxias orogenic gold deposit, São Luís cratonic fragment, Brazil

Caxias é um depósito de ouro orogênico do fragmento cratônico São Luís, que é correlacionável aos terrenos Riacianos do Cráton Oeste-Africano. O depósito se formou após o metamorfismo regional (estimado em 2100 ± 15 Ma) e está hospedado em zona de cisalhamento que secciona xistos do Grupo Aurizona (2240 ± 5 Ma) e o Microtonalito Caxias. O microtonalito foi aqui datado em 2009 ± 11 Ma, e representa um estágio magmático tardio na evolução do fragmento cratônico São Luís. Cristais de zircão com idades de 2139 ± 10 Ma foram herdados da fonte magmática ou são produto de contaminação durante a intrusão. A composição dos isótopos de chumbo sugere que granitoides de arco de ilhas de ca. 2160 Ma são a fonte provável para o Pb incorporado na pirita relacionada com o minério. Sericita hidrotermal mostra idade ⁴⁰Ar/³⁹Ar de 1990 ± 30 Ma, que, combinada com a idade de posicionamento do microtonalito hospedeiro, limita o evento mineralizador ao intervalo 2020-1960 Ma.