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| Registros recuperados: 22 | |
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| Marcon,Adriana Buarque; Barros,Iva Carneiro Leão; Guerra,Marcelo. |
| Foram analisadas citogeneticamente, através de técnicas de coloração convencional, sete espécies de pteridófitas homosporadas e três heterosporadas, pertencentes a oito famílias, sendo essas as primeiras contagens cromossômicas para essas espécies no Brasil. Dois parâmetros principais foram analisados no presente estudo: número cromossômico e tipos de núcleos interfásicos. Em algumas espécies, a morfologia cromossômica e a presença de satélites também foram avaliadas. De todas as espécies analisadas, duas não se tem conhecimento de contagens anteriores: Selaginella convoluta (Arn.) Spring (2n=24) e Thelypteris serrata (Cav.) Alston(2n=72), as quais apresentaram números já esperados para os gêneros. Nas demais espécies os números cromossômicos observados... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Pteridófitas; Número cromossômico; Núcleos interfásicos. |
| Ano: 2003 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-33062003000100002 |
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| Pedrosa,Andrea; Gitaí,Jailson; Silva,Ana Emília Barros e; Felix,Leonardo Pessoa; Guerra,Marcelo. |
| Foram analisadas 33 espécies, entre nativas e introduzidas, pertencentes a 20 famílias de angiospermas ocorrentes no Estado de Pernambuco. A caracterização cariotípica da maioria das espécies foi baseada no número e morfologia cromossômica, padrão de condensação de cromossomos profásicos e estrutura de núcleo interfásico. Cinco espécies tiveram seus números cromossômicos determinados pela primeira vez, sendo elas: Cereus jamacaru (2n=22), Clitoria fairchildiana (2n=22), Eugenia luschnathiana (2n=22), Licania tomentosa (2n=22) e Spondias tuberosa (n=16). No caso de Licania tomentosa esta é a primeira citação de número cromossômico para o gênero. Das outras 28 espécies, três (Cecropia cf. palmata, 2n=26; Crinum erubescens, 2n=70; e Schinus terebentifolius,... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Número cromossômico; Núcleo interfásico; Angiospermas. |
| Ano: 1999 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-33061999000100006 |
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| Carvalheira,Gianna Maria Griz; Guerra,Marcelo; Santos,Glauco Amaro dos; Andrade,Valmar Correia de; Farias,Mônica Cristina Alcantara de. |
| Neste trabalho são apresentados os números cromossômicos observados em 22 espécies pertencentes a 19 gêneros de angiospermas coletadas em Pernambuco. Os dados principais foram resumidos em uma tabela incluindo referências de herbário, locais de coleta, números diplóides e determinações cromossômicas prévias. Para oito espécies não encontramos nenhuma referência anterior na literatura específica. Por outro lado, alguns autores têm relatado números cromossômicos diferentes para uma mesma espécie. Nossas observações sugerem que essas discordâncias, em geral, podem ser atribuídas à ocorrência, nessas espécies, de cromossomos satelitados com constrições secundárias elásticas. Características citogenéticas especiais, observadas em algumas espécies, são também... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Números cromossômicos; Angiospermae. |
| Ano: 1991 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-33061991000200003 |
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| Guerra,Marcelo. |
| A citotaxonomia vegetal desenvolveu-se inicialmente nos países do primeiro mundo, acumulando dados e estabelecendo modelos evolutivos baseados principalmente em táxons e floras temperadas. A introdução de técnicas citogenéticas mais refinadas tem permitido uma análise mais acurada da variabilidade cariotípica, mas até o momento estes novos métodos têm sido aplicados apenas a um número muito pequeno de táxons. Assim, o principal instrumento do citotaxonomista continua sendo a variabilidade cromossômica numérica. A região tropical ainda é muito carente de dados, especialmente os trópicos americanos. No Brasil, a citotaxonomia se desenvolveu como parte da citogenética e não como uma abordagem taxonômica. Mesmo assim, nos últimos anos tem crescido o número de... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Citotaxonomia; Citogenética; Citotaxonomia no Brasil. |
| Ano: 1990 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-33061990000300009 |
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| Guerra,Marcelo; Pedrosa,Andrea; Silva,Ana Emília Barros e; Cornélio,Maria Tereza Marquim; Santos,Karla; Soares Filho,Walter dos Santos. |
| The mitotic chromosomes of 51 citrus accessions from the Centro Nacional de Pesquisa em Mandioca e Fruticultura Tropical, Cruz das Almas, BA, Brazil, were analyzed. The sample included representatives of 20 Citrus species, one of Poncirus and seven hybrids. All accessions showed 2n = 18 without any evidence of numerical variation. The most clearly variable karyotype feature was the number and position of secondary constrictions (SECs). In 19 accessions the SECs were not identified, mainly due to the degree of chromatin condensation. In the remainder they varied in number from one to three per karyotype. They were found in the proximal region of one of the three largest chromosome pairs, in the terminal/subterminal region of a smaller chromosome or, more... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1997 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84551997000300021 |
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| Guerra,Marcelo. |
| Abstract Agmatoploidy is a type of chromosome rearrangement that involves the fragmentation of an entire chromosome complement, generating a diploid with double its original chromosome number. Agmatoploidy and other related karyotype changes, such as symploidy (the opposite change, promoted by chromosome fusion), partial agmatoploidy, polyagmatoploidy, etc., are restricted to species with holokinetic chromosomes and are assumed to play an important role in their karyotype evolution. However, a critical review of the literature shows that examples of chromosome number doubling by agmatoploidy are rare and not clearly demonstrated, while partial agmatoploidy and partial symploidy seem to be the same as ascending and descending disploidy, respectively. It is... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Agmatoploidy; Symploidy; Holocentrics; Holokinetic chromosomes; Chromosome evolution. |
| Ano: 2016 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572016000400492 |
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| Félix,Leonardo Pessoa; Guerra,Marcelo. |
| The Cymbidioid phylad presents the widest chromosome number variation among orchids, with records varying from 2n = 10 in Psygmorchis pusilla to 2n = 168 in two species of Oncidium. In the present work, a total of 44 species were studied belonging to 20 Cymbidioid genera, as a contribution to clarifying the karyological evolution of the group. All the plants investigated were collected in Brazil, mainly in the northeast region. The chromosome variation found was similar to that previously registered in the literature. Chromosome numbers observed were: 2n = 54 (subtribe Eulophiinae), 2n = 44, 46, 92 (subtribe Cyrtopodiinae), 2n = 54, ca. 108 (subtribe Catasetinae), 2n = 52, ca. 96 (subtribe Zygopetalinae), 2n = 40, 80 (subtribe Lycastinae), 2n = 40, 42... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 2000 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572000000400041 |
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| Dantas,Liliane G.; Guerra,Marcelo. |
| A comparative analysis of mitotic chromosomes of Theobroma cacao (cacao) and T. grandiflorum (cupuaçu) was performed aiming to identify cytological differences between the two most important species of this genus. Both species have symmetric karyotypes, with 2n = 20 metacentric chromosomes ranging in size from 2.00 to 1.19 µm (cacao) and from 2.21 to 1.15 mm (cupuaçu). The interphase nuclei of both species were of the arreticulate type, displaying up to 20 chromocentres, which were more regularly shaped in cacao than in cupuaçu. Prophase chromosomes of both species were more condensed in the proximal region, sometimes including the whole short arm. Both species exhibited only one pair of terminal heterochromatic bands, positively stained with chromomycin... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Cacao; Cupuaçu; Heterochromatin; Karyotype; RDNA sites; Theobroma. |
| Ano: 2010 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572010000100017 |
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| Souza,Luiz G.R.; Crosa,Orfeo; Winge,Helga; Guerra,Marcelo. |
| The genus Nothoscordum Kunth comprises approximately 20 species native to South America. Karyologically, the genus is remarkable for its large chromosomes and Robertsonian translocations. Variation in chromosome number has been recorded in a few polyploid species and it is unknown among diploids. This study presents the chromosome number and morphology of 53 individuals of seven populations of N. arenarium Herter (2n = 10). In addition, karyotype analyses after C-banding, staining with CMA and DAPI, and in situ hybridization with 5S and 45S rDNA probes were performed in six individuals from one population. All individuals exhibited 2n = 10 (6M + 4A), except for one tetraploid (2n = 20, 12M + 8A) and one triploid (2n = 15, 9M + 6A) plant. C-banding revealed... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: CMA/DAPI staining; 5S and 45S rDNA; Heterochromatin; Nothoscordum; Robertsonian translocation. |
| Ano: 2009 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572009000100016 |
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| Brasileiro-Vidal,Ana Christina; Cuadrado,Angeles; Brammer,Sandra P.; Zanatta,Ana Christina A.; Prestes,Ariano M.; Moraes-Fernandes,Maria Irene B.; Guerra,Marcelo. |
| Thinopyrum ponticum (2n = 10x = 70, JJJJsJs) belongs to the Triticeae tribe, and is currently used as a source of pathogen resistance genes in wheat breeding. In order to characterize its chromosomes, the number and position of 45S and 5S rDNA sites, as well as the distribution of the repetitive DNA sequences pAs1 and pSc119.2, were identified by fluorescent in situ hybridization. The number of nucleoli and NORs was also recorded after silver nitrate staining. Seventeen 45S and twenty 5S rDNA sites were observed on the short arms of 17 chromosomes, the 45S rDNA was always located terminally. On three other chromosomes, only the 5S rDNA site was observed. Silver staining revealed a high number of Ag-NORs (14 to 17) on metaphase chromosomes, whereas on... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Thinopyrum; Silver staining; 45S and 5S rDNA; PSc119.2; PAs1. |
| Ano: 2003 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572003000400014 |
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| Vanzela,André L.L.; Guerra,Marcelo. |
| Holocentric chromosomes of six species of Rhynchospora, R. ciliata, R. pubera, R. riparia and R. barbata (2n = 10), R. nervosa (2n = 30) and R. globosa (2n = 36), were stained with CMA3/DAPI fluorochromes or treated with C-banding and sequentially stained with Giemsa or CMA3/DAPI. Variability in banding pattern was found among the species studied. Heterochromatin was observed on terminal and interstitial chromosome regions, indicating that the holocentric chromosomes of Rhynchospora show a heterochromatin distribution pattern similar to those plant monocentric chromosomes. |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 2000 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572000000200034 |
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| Brasileiro-Vidal,Ana Christina; Cuadrado,Angeles; Brammer,Sandra P.; Benko-Iseppon,Ana Maria; Guerra,Marcelo. |
| The wheat line PF 839197 and six hybrid derivatives from a cross between PF 839197 and Thinopyrum ponticum were cytologically characterized by fluorescent in situ hybridization (FISH). Probes for the 5S and 45S rDNA genes (pTa794 and pTa71, respectively), a highly repetitive rye sequence (pSc119.2), the synthetic oligonucleotide (AAG)5, and total genomic DNA from Th. ponticum and rye were used. In the wheat line, a 1RS.1BL translocation was revealed by the labeling patterns produced with pSc119.2 and (AAG)5, and confirmed by genomic in situ hybridization (GISH) using rye genomic DNA as a probe. Analyses of partial amphiploids confirmed previous results indicating mitotic instability, with a tendency to stabilize at 2n = 42 or 56. GISH with Th. ponticum... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Wheat; Thinopyrum ponticum; Rye; Hybrid derivatives; GISH. |
| Ano: 2005 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572005000200022 |
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| Guerra,Marcelo. |
| The C-band distribution patterns of 105 angiosperm species were compared to identify general patterns or preferential sites for heterochromatin. The base-specific fluorochrome reaction of heterochromatin for 58 of these species and the role played by the average chromosome size in band distribution were also considered. The results showed that heterochromatin was preferentially located in similar chromosome regions, regardless of the distance from the centromere. This trend results in generalized bands, with heterochromatin distribution being identical in most chromosomes of a karyotype. Such bands very often displayed the same fluorochrome reaction, suggesting possible repeat transfer between non-homologous sites. Chromosome size may also play a role in... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 2000 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572000000400049 |
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| Registros recuperados: 22 | |
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