Chromosome Evolution in African Cichlid Fish: Contributions from the Physical Mapping of Repeated DNAs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Differentiation of the XY Sex Chromosomes in the Fish Hoplias malabaricus (Characiformes, Erythrinidae): Unusual Accumulation of Repetitive Sequences on the X Chromosome

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Characterization of invasive fish species in a river transposition region: evolutionary chromosome studies in the genus Hoplias (Characiformes, Erythrinidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Comparative cytogenetic mapping of Sox2 and Sox14 in cichlid fishes and inferences on the genomic organization of both genes in vertebrates

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Chromosomal mapping of rDNAs and H3 histone sequences in the grasshopper rhammatocerus brasiliensis (acrididae, gomphocerinae): extensive chromosomal dispersion and co-localization of 5S rDNA/H3 histone clusters in the A complement and B chromosome

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Chromosome mapping of repetitive sequences in Anostomidae species: Implications for genomic and sex chromosome evolution

Background: Members of the Anostomidae family provide an interesting model system for the study of the influence of repetitive elements on genome composition, mainly because they possess numerous heterochromatic segments and a peculiar system of female heterogamety that is restricted to a few species of the Leporinus genus. The aim of this study was to isolate and identify important new repetitive DNA elements in Anostomidae through restriction enzyme digestion, followed by cloning, characterisation and chromosome mapping of this fragment. To identify repetitive elements in other Leporinus species and expand on studies of repetitive elements in Anostomidae, hybridisation experiments were also performed using previously described probes of LeSpeI repetitive elements. Results: The 628-base pair (bp) LeSpeII fragment was hybridised to metaphase cells of L. elongatus individuals as well as those of L. macrocephalus, L. obtusidens, L. striatus, L. lacustris, L. friderici, Schizodon borellii and S. isognathus. In L. elongatus, both male and female cells contained small clusters of LeSpeII repetitive elements dispersed on all of the chromosomes, with enrichment near most of the terminal portions of the chromosomes. In the female sex chromosomes of L. elongatus (Z2,Z2/W1W 2), however, this repeated element was absent. In the remaining species, a dispersed pattern of hybridisation was observed on all chromosomes irrespective of whether or not they were sex chromosomes. The repetitive element LeSpeI produced positive hybridisations signals only in L. elongatus, L. macrocephalus and L. obtusidens, i.e., species with differentiated sex chromosomes. In the remaining species, the LeSpeI element did not produce hybridisation signals. Conclusions: Results are discussed in terms of the effects of repetitive sequences on the differentiation of the Anostomidae genome, especially with respect to sex chromosome evolution. LeSpeII showed hybridisation patterns typical of Long Interspersed Elements (LINEs). The differential distribution of this element may be linked to sex chromosome differentiation in L. elongatus species. The relationship between sex chromosome specificity and the LeSpeI element is confirmed in the species L. elongatus, L. macrocephalus and L. obtusidens. © 2012 da Silva et al.; licensee BioMed Central Ltd.

First cytogenetic information for Drymoreomys albimaculatus (Rodentia, Cricetidae), a recently described genus from Brazilian Atlantic forest

The recently described taxon Drymoreomys albimaculatus is endemic to the Brazilian Atlantic Forest and its biology and genetics are still poorly known. Herein, we present, for the first time, the karyotype of the species using classical and molecular cytogenetics, which showed 2n=62, FN=62, and interstitial telomeric signals at the sex chromosomes. Nuclear and mitochondrial DNA sequences from the two karyotyped individuals verify the taxonomic identity as the recently described D. albimaculatus and confirm the relationship of the species with other Oryzomyini. Additionally, external morphological information is provided. © Elkin Y. Suárez-Villota et al.

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.

Aplicação de pintura cromossômica em espécies da família Accipitridae (Aves, Falconiformes): considerações filogenéticas e evolutivas

As análises citogenéticas de diversos Falconiformes mostraram que os acipitrídeos têm uma organização cromossômica atípica na classe Aves, com um número diplóide relativamente baixo (média de 2n= 66) e poucos pares de microcromossomos (4 a 6 pares). Propostas baseadas em citogenética clássica sugeriram que esse fato devia-se à fusão de microcromossomos presentes no cariótipo ancestral das Aves. No intuito de contribuir para o esclarecimento das questões referentes à evolução cromossômica e filogenética dessa família, três espécies da subfamília Buteoninae (Rupornis magnirostris, Buteogallus meridionales e Asturina nitida) e duas espécies da subfamília Harpiinae (Harpia harpyja e Morphnus guianensis) foram analisados citogeneticamente através da aplicação de técnicas de citogenética clássica e molecular. As espécies de Buteoninae apresentaram cariótipos muito semelhantes, com número diplóide igual a 68; o número de cromossomos de dois braços entre 17 e 21, o cromossomo Z submetacêntrico e o W metacêntrico em R. magnirostris e submetacêntrico em Asturina nitida. O uso de sondas de 18/28S rDNA mostrou a localização de regiões organizadoras de nucléolo em um par submetacêntrico médio nas três espécies, correspondendo ao braço curto do par 7. Sequências teloméricas foram mapeadas não só na região terminal dos braços, mas também em algumas posições intersticiais. Sondas de cromossomo inteiro derivadas dos pares 1 a 10 de Gallus gallus (GGA) produziram o mesmo número de sinais nessas três espécies. A disponibilidade das sondas de cromossomos totais derivadas de Leucopternis albicollis confirmou a existência de uma assinatura citogenética comum para as espécies de Buteoninae analisadas por FISH, que se trata da associação entre GGA1p e GGA6, inclusive com um sítio de sequência telomérica intersticial reforçando esse fato. As espécies de Harpiinae analisadas mostraram que o número diplóide das espécies de H. harpyja e M. guianensis foi igual a 58 e 54, respectivamente, e que ambas as espécies apresentam vinte e dois pares de cromossomos de dois braços, mesmo Harpia apresentando dois pares a mais. 18/28S rDNA produziram sinais no braço curto do par 1 em M. guianensis e em dois pares em H. harpyja (pares 6 e 25). Sequências teloméricas intersticiais também foram observadas em alguns pares. Apesar da similaridade na morfologia cromossômica, não foram observadas associações compartilhadas por essas duas espécies. As diferentes associações observadas em Morphnus e Harpia mostram que essas espécies sofreram uma reorganização genômica expressiva após sua separação em linhagens independentes. Além disso, ausência de associações semelhantes sugere que houve fissões nos macrocromossomos do ancestral em comum desse grupo, e as fusões foram subsequentes ao seu isolamento como linhagens diferentes. Os resultados aqui apresentados, somados àqueles publicados anteriormente com outras espécies de Accipitridae indicam que os processos de fissões envolvendo os macrocromossomos de GGA e fusões entre esses segmentos e entre esses e microcromossomos são rearranjos recorrentes nesse grupo. Apesar dos Falconidae também apresentarem cariótipos atípicos, e números diploides baixos, os dados globais da citogenética de Accipitridae indicam que, assim como postulado para as semelhanças morfológicas entre esses dois grupos, os cariótipos rearranjados corresponderiam a homoplasias, do ponto de vista evolutivo, apoiando que essas duas famílias não formam um grupo monofilético.

Alterações cromossômicas estruturais e evolução caritotípica em Astyanax fasciatus (Teleostei, Characiformes, Characidae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Variabilidade genética e variação das regiões heterocromáticas em linhagens de Triatoma infestans (Heteroptera : Reduviidae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Chromosomal organization and evolutionary history of Mariner transposable elements in Scarabaeinae coleopterans

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Cytogenetic analysis in three Bryconamericus species (Characiformes, Characidae): first description of the 5S rDNA-bearing chromosome pairs in the genus

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Comparative Chromosome Mapping of U2 snRNA and 5S rRNA Genes in Gymnotus Species (Gymnotiformes, Gymnotidae): Evolutionary Dynamics and Sex Chromosome Linkage in G. pantanal

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Surface-spreading technique of meiotic cells and immunodetection of synaptonemal complex proteins in teleostean fishes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)