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Search Results: 1 - 10 of 208831 matches for " Vladimir P. Margarido "
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The pioneering use of ISSR (Inter Simple Sequence Repeat) in Neotropical anurans: preliminary assessment of genetic diversity in populations of Physalaemus cuvieri (Amphibia, Leiuperidae)
Rafaela M Moresco,Thiago C Maniglia,Classius De Oliveira,Vladimir P Margarido
Biological Research , 2013,
Abstract: The greatest diversity of anurans in the world is in Brazil and one of the major challenges is to reconcile the accelerated economic development with strategies that aim to maintain this diversity in forest fragments, often representing ESUs of some biomes. This study aimed to obtain data that will support conservation projects through the pioneering use of ISSR analysis in Neotropical anurans, estimating the intra- and interpopulation genetic diversity of four populations of P. cuvieri (Paraná and S o Paulo regions). Of the 65 loci scored 58 were polymorphic, with 0.797 intrapopulation variation and 0.203 interpopulation variation. The index of interpopulation genetic differentiation (Fst) proved to be high among the population of Marmeleiro-PR and the three populations of SP (Fst > 0.288); genetic dissimilarity was related to the geographical distance. The ISSR proved to be efficient and useful molecular markers in comparison with other markers most widely used for preliminary diagnosis of genetic diversity in populations of amphibians, and could be applied as a tool for future conservation projects, since they could identify potential ESUs and influence decisions on the preservation of fragments.
Heterochromatin patterns and karyotype relationships within and between the genera Brycon and Salminus (Pisces, Characidae)
Margarido, Vladimir Pavan;Galetti Junior, Pedro Manoel;
Genetics and Molecular Biology , 1999, DOI: 10.1590/S1415-47571999000300012
Abstract: chromosomes of two brycon species (b. lundii and b. microlepis) and salminus hilarii were analyzed. based on constitutive heterochromatin distribution patterns, karyotypic relationships within and between bryconinae and salmininae were examined. a monophyletic origin for the genus brycon, comprising at least two chromosome synapomorphies (presence of two large submetacentric bearing paracentromeric and telomeric heterochromatin), is suggested. moreover, bryconinae and salmininae may represent a monophyletic unit among characidae, as they share several chromosome features.
Amplification of a GC-rich heterochromatin in the freshwater fish Leporinus desmotes (Characiformes, Anostomidae)
Margarido, Vladimir Pavan;Galetti Junior, Pedro Manoel;
Genetics and Molecular Biology , 2000, DOI: 10.1590/S1415-47572000000300012
Abstract: this is the first description of the karyotype of leporinus desmotes. the diploid female number was 2n = 54 meta- and submetacentric chromosomes. the nucleolar organizing regions (nors) were studied by silver nitrate staining and rdna fluorescence in situ hybridization (fish) and were found to be located in the telomeric region of the long arm of the 9th pair. c-banding revealed centromeric and telomeric heterochromatin segments in most chromosomes. intercalar blocks of heterochromatin were observed in the long arm of six chromosome pairs. besides a nor-adjacent heterochromatin, all of the intercalar heterochromatic segments were brightly fluorescent by mithramycin staining. these data suggest that a unique amplification of a primordial gc-rich heterochromatin, probably nor-associated, may have taken place in the karyotype diversification of this leporinus species.
Karyotypic differentiation through chromosome fusion and number reduction in Imparfinis hollandi (Ostariophysi, Heptapteridae)
Margarido, Vladimir Pavan;Moreira-Filho, Orlando;
Genetics and Molecular Biology , 2008, DOI: 10.1590/S1415-47572008000200012
Abstract: the neotropical heptapteridae fish imparfinis hollandi, endemic to the igua?u river basin (brazil), was cytogenetically analyzed and the diploid chromosome number of 2n = 42 chromosomes was determined (22m + 10sm + 10st), the lowest diploid number in this genus and family. like other heptapteridae species, only one nor-bearing chromosome pair was detected by silver nitrate staining. dark heterochromatic blocks were visualized in only three chromosome pairs, and chromomycin a3+ bands were coincident with ag-nors. although no intercalary (ttaggg)n sequence was observed through fish with a telomere probe, an asymmetric karyotype showing four large chromosome pairs with diploid chromosome number reduction suggests that tandem chromosome fusions probably occurred during the karyotypic differentiation of imparfinis hollandi.
Cytogenetic studies in three species of the genus Oligosarcus
Rubert, Marceléia;Margarido, Vladimir Pavan;
Brazilian Archives of Biology and Technology , 2007, DOI: 10.1590/S1516-89132007000100015
Abstract: karyotypic studies were carried out on three species of the genus oligosarcus: o. paranensis, o. pintoi, and o. longisrostris. all of them showed a diploid number of 50 chromosomes and the same karyotypic formulae (4m + 10sm + 16st + 20a). silver nitrate staining revealed single nors in o. longirostris and multiple nors in o. paranensis and o. pintoi. heterochromatin seemed to play an important role in the chromosomal diversification of these species. based on cytogenetical data, speciation hypotheses within this group were proposed, reinforcing the importance of chromosomal studies for a better understanding of evolution within the genus oligosarcus, as well as within the family characidae.
Amplification of a GC-rich heterochromatin in the freshwater fish Leporinus desmotes (Characiformes, Anostomidae)
Margarido Vladimir Pavan,Galetti Junior Pedro Manoel
Genetics and Molecular Biology , 2000,
Abstract: This is the first description of the karyotype of Leporinus desmotes. The diploid female number was 2n = 54 meta- and submetacentric chromosomes. The nucleolar organizing regions (NORs) were studied by silver nitrate staining and rDNA fluorescence in situ hybridization (FISH) and were found to be located in the telomeric region of the long arm of the 9th pair. C-banding revealed centromeric and telomeric heterochromatin segments in most chromosomes. Intercalar blocks of heterochromatin were observed in the long arm of six chromosome pairs. Besides a NOR-adjacent heterochromatin, all of the intercalar heterochromatic segments were brightly fluorescent by mithramycin staining. These data suggest that a unique amplification of a primordial GC-rich heterochromatin, probably NOR-associated, may have taken place in the karyotype diversification of this Leporinus species.
Heterochromatin patterns and karyotype relationships within and between the genera Brycon and Salminus (Pisces, Characidae)
Margarido Vladimir Pavan,Galetti Junior Pedro Manoel
Genetics and Molecular Biology , 1999,
Abstract: Chromosomes of two Brycon species (B. lundii and B. microlepis) and Salminus hilarii were analyzed. Based on constitutive heterochromatin distribution patterns, karyotypic relationships within and between Bryconinae and Salmininae were examined. A monophyletic origin for the genus Brycon, comprising at least two chromosome synapomorphies (presence of two large submetacentric bearing paracentromeric and telomeric heterochromatin), is suggested. Moreover, Bryconinae and Salmininae may represent a monophyletic unit among Characidae, as they share several chromosome features.
Cytotaxonomy of Parodon nasus and Parodon tortuosus (Pisces, Characiformes): A case of synonymy confirmed by cytogenetic analyses
Bellafronte, Elisangela;Margarido, Vladimir Pavan;Moreira-Filho, Orlando;
Genetics and Molecular Biology , 2005, DOI: 10.1590/S1415-47572005000500010
Abstract: morphological and cytogenetical studies were carried out on the freshwater fish parodon nasus and parodon tortuosus in order to evaluate a putative synonymy. the diploid chromosome number observed in both species was 2n = 54 (48m/sm and 6st) with no differences between the sexes. despite slight differences in the pattern of heterochromatin distribution and the number of cusps in symphysean teeth, the location of nucleolar organizer regions (nors) and 5s rrna genes (both species-specific features) were similar in both species. the remarkable similarity observed between these allopatric species supports recent taxonomical reviews indicating that p. tortuosus is a synonym for p. nasus.
Natural triploidy in Leporinus cf. elongatus bearing sex chromosomes
Molina, Wagner Franco;Margarido, Vladimir Pavan;Galetti Jr, Pedro Manoel;
Genetics and Molecular Biology , 2007, DOI: 10.1590/S1415-47572007000400010
Abstract: although several cases of natural triploidy in fish have already been described, spontaneous polyploidy in species with differentiated sex chromosomes are rare. we report the occurrence of a triploid fish (3n = 81) leporinus cf. elongatus, a species characterized by a highly differentiated zz/zw sex chromosome system, from the s?o francisco river. the occurrence of a zzz triploid adult indicates the viability of this chromosome constitution in this fish.
Karyotypic diversity between allopatric populations of the group Hoplias malabaricus (Characiformes: Erythrinidae): evolutionary and biogeographic considerations
Blanco, Daniel Rodrigues;Lui, Roberto Laridondo;Bertollo, Luiz Antonio Carlos;Margarido, Vladimir Pavan;Moreira Filho, Orlando;
Neotropical Ichthyology , 2010, DOI: 10.1590/S1679-62252010000200015
Abstract: three populations of the group hoplias malabaricus from the hydrographic basins of the s?o francisco, araguaia/tocantins and xingu rivers in brazil were analyzed using classic cytogenetic methods (giemsa staining, c-banding and ag-nors) and molecular methods (fluorescent in situ hybridization with 18s rdna, 5s rdna and 5shindiii satellite dna probes). the chromosome markers allowed the characterization of these populations as belonging to karyomorph a and the detection of inter-population divergences. these differences likely stem from different evolutionary histories resulting from geographic isolation between populations associated to the dispersive mode of these organisms, reinforcing genetic diversity in the group hoplias malabaricus.
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