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Registros recuperados: 70 | |
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Porto-Foresti,Fábio; Oliveira,Claudio; Maistro,Edson Luis; Foresti,Fausto. |
A study was made of the frequency of B-chromosomes and the population density of Astyanax scabripinnis paranae (Pisces, Characidae, Tetragonopterinae) from three stretches of the Cascatinha stream (Botucatu, SP). In the first stretch the population was estimated to be about 212 individuals and among 35 karyotyped specimens, 23 carried one macro B-chromosome; in the second stretch the population was estimated to be about 650 individuals and among 20 specimens karyotyped, two possessed one macro B-chromosome; in the third stretch the population was estimated to be about 107 individuals and among 10 specimens karyotyped, one carried one macro B-chromosome. A significant difference was observed in the frequency of macro B-chromosomes in females (57%) and males... |
Tipo: Info:eu-repo/semantics/article |
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Ano: 1997 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84551997000300004 |
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Carvalho,Margarida Lima; Oliveira,Claudio; Foresti,Fausto. |
The present paper reports nuclear DNA content in 30 Neotropical freshwater fish species and summarizes the data on other Neotropical species presented in the literature. Among Neotropical fishes, the nuclear DNA content ranges from 1.04 ± 0.09 pg/nucleus in Corydoras cf. simulatus (2n = 62) to 248.0 pg/nucleus in Lepidosiren paradoxa (2n = 38). A general analysis of the data obtained in the present study for each species showed that DNA measurements were practically constant at the individual level, while significant differences were observed among individuals of the same population. This observation was valid for all species analyzed and was more evident in those species that presented other karyotypic particularities such as sex chromosomes or... |
Tipo: Info:eu-repo/semantics/article |
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Ano: 1998 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47571998000100009 |
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Maistro,Edson Luis; Oliveira,Claudio; Foresti,Fausto. |
Cytogenetic and morphological studies were carried out on nine local populations of Astyanax scabripinnis paranae. All populations exhibited 2n = 50 chromosomes as well as conspicuous differences involving karyotype morphology, number and position of nucleolar organizer regions (NORs) and amount and/or locations of constitutive heterochromatin blocks. A quantitative study of the cytogenetic data showed that eight populations possessed different karyotypes. Morphological analyses based on nine measurements and two meristic parameters were effective in establishing clear identification of five populations. Comparative analysis of cytogenetic and morphological traits suggests that chromosomal changes have occurred at a more rapid rate than morphological... |
Tipo: Info:eu-repo/semantics/article |
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Ano: 1998 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47571998000200005 |
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Maistro,Edson Luis; Foresti,Fausto; Oliveira,Claudio. |
The absence of longitudinal bands in fish chromosomes has been associated with technical problems in chromosome preparations or the absence of a structural compartmentalization in the fish genome. In the present study, a R-banding pattern was obtained using a replication banding technique by in vivo treatment with 5-bromodeoxyuridine (5-BrdU). G-banding patterns were obtained after trypsin treatment and also after chromosome cleavage by in situ treatment with the restriction endonuclease BamHI. A similar G-banding pattern was also obtained after cleavage with the endonuclease HinfI. Presence of a resolute R- and G-banding patterns shows that Astyanax scabripinnis paranae chromosomes could present an isochore-like structure similar to that found in other... |
Tipo: Info:eu-repo/semantics/article |
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Ano: 1999 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47571999000200011 |
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Maistro,Edson Luis; Oliveira,Claudio; Foresti,Fausto. |
Among four specimens of Astyanax scabripinnis sympatrically collected from the Tamanduá stream (State of São Paulo, Brazil), three, named cytotype I, had 2n = 50 chromosomes (6M + 26SM + 4ST + 14A) and a fundamental number (FN) of 86, and one specimen, named cytotype II, had 2n = 48 chromosomes (6M + 28SM + 4ST + 10A) and FN = 86. Besides the difference in diploid number, the cytotypes showed a clear difference in the distribution of constitutive heterochromatin. One NOR-bearing chromosome pair was detected in both cytotypes and one specimen of cytotype I had multiple NORs (tree chromosome pairs). Robertsonian translocations and an increase or loss of heterochromatin are proposed to explain the karyotypic divergence observed. Some aspects related to the... |
Tipo: Info:eu-repo/semantics/other |
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Ano: 2000 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572000000200021 |
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Carvalho,Margarida Lima; Oliveira,Claudio; Foresti,Fausto. |
The family Gasteropelecidae is composed of three genera and eight species. This study shows that Thoracocharax cf. stellatus has 2n = 52 chromosomes for both sexes. The five males studied showed 8 metacentric, 16 submetacentric, 4 subtelocentric, and 24 acrocentric chromosomes; the seven females showed only one submetacentric chromosome, belonging to pair 11, and one extra acrocentric chromosome, smaller than all the other chromosomes, characterizing the presence of a ZZ/ZW sex chromosome system in this species. Nucleolus organizing regions (NORs) were detected on the short arms of the subtelocentric chromosome pair 13. Constitutive heterochromatin was identified at pericentromeric and terminal positions in almost all chromosomes. The W chromosome was... |
Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Sex chromosomes; ZW; DNA content; Fish; Evolution. |
Ano: 2002 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572002000300008 |
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Porto-Foresti,Fábio; Oliveira,Claudio; Tabata,Yara A.; Rigolino,Marcos G.; Foresti,Fausto. |
In salmonid species, nucleolar organizing regions (NORs) have frequently been found on a single chromosome pair. However, some other, smaller yet active NORs have also been described. In the present study, NORs were found to be located in different positions on the chromosomes of 12 rainbow trout samples (11 cultivated and one naturalized stocks). Three phenotypes were found: 1) NORs located on two submetacentric chromosomes, in a subterminal position on the short arm (AA); 2) NORs located on two submetacentric chromosomes, in a subterminal position on the long arm (BB); and 3) NORs located on two submetacentric chromosomes, one in a subterminal position on the short arm, and the other in a subterminal position on the long arm (AB). Phenotype AA was... |
Tipo: Info:eu-repo/semantics/article |
Palavras-chave: NOR polymorphism; Fish cytogenetics; Rainbow trout. |
Ano: 2002 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572002000400009 |
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Quagio-Grassiotto,Irani; Gameiro,Maria Carolina; Schneider,Tatiana; Malabarba,Luiz Roberto; Oliveira,Claudio. |
Spermiogenesis in the curimatid species, Steindachnerina insculpta, Cyphocharax gillii, C. modestus, C. spilotus, and Potamorhina altamazonica, is characterized by lateral development of the flagellum, nuclear rotation, eccentric nuclear fossa formation, and chromatin compacted into thick fibers. These spermatozoa exhibit a spherical head containing a nucleus with the chromatin highly condensed into thick fibers with small electron-lucent areas, and no acrosome. The nuclear fossa is of the moderate type and eccentric and penetrated by the centriolar complex. The midpiece is small, has many elongate vesicles, and a short cytoplasmic channel. Mitochondria may be elongate, branched or C-shaped, and are separated from the initial segment of the axoneme by the... |
Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Fish; Spermatid; Sperm; Ultrastructure. |
Ano: 2003 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252003000100004 |
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Oliveira,Claudio; Nirchio,Mauro; Granado,Ángel; Levy,Sara. |
Fish of the family Prochilodontidae are considered one of the most important components of commercial and subsistence fishery in freshwater environments in South America. This family consists of 21 species and three genera. In the present study, the karyotypes of Prochilodus mariae, Semaprochilodus kneri, and S. laticeps from Caicara del Orinoco, Bolivar State, Venezuela were studied. The species P. mariae, S. kneri and S. laticeps exhibited 2n=54 chromosomes (40 metacentric and 14 submetacentric), a single chromosome pair with nucleolus organizer regions, and a large amount of heterochromatin found at centromeric and pericentromeric positions in almost all chromosomes. The P. mariae specimens studied displayed 0 to 3 supernumerary microchromosomes. The... |
Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Karyotype; C-band; NOR banding; Chromossome evolution; Characiformes. |
Ano: 2003 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252003000100005 |
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Sato,Luciana Ramos; Oliveira,Claudio; Foresti,Fausto. |
Trichomycteridae is a family of small catfish which are widely distributed throughout Southern Central America and South America. The present study showed that the cis-Andean species Trichomycterus florensis, Trichomycterus sp. aff. Trichomycterus itatiyae, Trichomycterus reinhardti, Trichomycterus davisi and Trichomycterus auroguttatus had 2n = 54 chromosomes (42 metacentric, 10 submetacentric and 2 subtelocentric), with T. reinhardti, T. auroguttatus and T. sp. aff. T. itatiyae exhibiting only one chromosome pair with silver-stained nucleolus organizer regions (NORs). The cytogenetic data suggest the existence of at least two groups of species in the cis-Andean representatives of the genus Trichomycterus. In the first group the first metacentric pair is... |
Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Chromosome evolution; NOR banding; Fish. |
Ano: 2004 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572004000100008 |
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Quagio-Grassiotto,Irani; Spadella,Maria Angélica; Carvalho,Márcio de; Oliveira,Claudio. |
The data obtained in the present study on spermiogenesis and spermatozoal ultrastructure of Pseudopimelodidae and Heptapteridae show that they share some characteristics, but greatly differ from each other. The main differences are the occurrence of type I spermiogenesis in Pseudopimelodidae and type III in Heptapteridae, the presence of nuclear fossa in Pseudopimelodidae and its absence in Heptapteridae, the presence of long midpiece in Pseudopimelodidae and short midpiece in Heptapteridae, the presence of cytoplasmic canal in Pseudopimelodidae and its absence in Heptapteridae, the presence of many large vesicles in the midpiece of Pseudopimelodidae and the presence of very long vesicles placed in the peripheral distal region in Heptapteridae, and... |
Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Catfish; Spermatid; Sperm; Structure; Phylogeny. |
Ano: 2005 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252005000300008 |
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Registros recuperados: 70 | |
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