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Registros recuperados: 109
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A 37-kb restriction map of the human immunoglobulin lambda variable locus, VB cluster, harboring four functional genes and two non-coding Vl sequences Braz. J. Genet.
Passos Jr.,Geraldo A.S.; Lefranc,Marie-Paule.
The human immunoglobulin lambda variable locus (IGLV) is mapped at chromosome 22 band q11.1-q11.2. The 30 functional germline v-lambda genes sequenced untill now have been subgrouped into 10 families (V<FONT FACE="Symbol">l</font>1 to V<FONT FACE="Symbol">l</font>10). The number of V<FONT FACE="Symbol">l</font> genes has been estimated at approximately 70. This locus is formed by three gene clusters (VA, VB and VC) that encompass the variable coding genes (V) responsible for the synthesis of lambda-type Ig light chains, and the J<FONT FACE="Symbol">l</font>-C<FONT FACE="Symbol">l</font> cluster with the joining segments and the constant genes. Recently the entire variable lambda gene locus was...
Tipo: Info:eu-repo/semantics/article
Ano: 1997 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84551997000400027
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A comparative study of eleven protein systems in tamarins, genus Saguinus (Platyrrhini, Callitrichinae) Braz. J. Genet.
The genetic variability of six tamarin taxa, genus Saguinus, was analyzed comparatively using protein data from eleven systems coded by 15 loci. S. fuscicollis weddelli and S. midas midas were the most polymorphic taxa, and S. bicolor the least. The results of the phylogenetic analyses (UPGMA and neighbor-joining) and the genetic distances between taxa were generally consistent with their geographic and probable phylogenetic relationships. Analyses of the S. bicolor and S. midas populations suggested that they represent no more than three subspecies of a single species, S. midas, with the bicolor forms belonging to a single subspecies, S. midas bicolor. If supported by additional studies, this would have important implications for the conservation of the...
Tipo: Info:eu-repo/semantics/other
Ano: 1997 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84551997000100003
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A new allele of peptidase-B in cattle Braz. J. Genet.
Electrophoretic analyses of peptidase-B were carried out on red cell hemolysates from Holstein, Mantiqueira and Gyr cattle, using cornstarch, known in Brazil as Penetrose-30. We describe a new peptidase-B allele, denoted Pep-B1, in Mantiqueira cattle, belonging to the Bos taurus group, which are the result of a cross of native cattle of Portuguese origin introduced in Brazil during colonial times (16th century) with Holstein and Caracu cattle. The genetic control of peptidase-B was determined by typing parents and progeny segregating for all three alleles, confirming that peptidase B is controlled by a single autosomal locus with three codominant alleles, denoted Pep-B1, Pep-B2 and Pep-B3 The use of the citrate-phosphate buffer system, at pH 5.9, on 14%...
Tipo: Info:eu-repo/semantics/other
Ano: 1997 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84551997000100002
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A search for RFLP markers to identify genes for aluminum tolerance in maize Braz. J. Genet.
Torres,Giovana A.; Parentoni,Sidney N.; Lopes,Maurício A.; Paiva,Edilson.
The objective of this study was to identify restriction fragment length polymorphism (RFLP) markers linked to QTLs that control aluminum (Al) tolerance in maize. The strategy used was bulked segregant analysis (BSA) and the genetic material utilized was an F2 population derived from a cross between the Al-susceptible inbred line L53 and Al-tolerant inbred line L1327. Both lines were developed at the National Maize and Sorghum Research Center - CNPMS/EMBRAPA. The F2 population of 1554 individuals was evaluated in a nutrient solution containing a toxic concentration of Al and relative seminal root length (RSRL) was used as a phenotypic measure of tolerance. The RSRL frequency distribution was continuous, but skewed towards Al-susceptible individuals....
Tipo: Info:eu-repo/semantics/article
Ano: 1997 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84551997000300017
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A simple model for the estimation of congenital malformation frequency in racially mixed populations Braz. J. Genet.
Lopez-Camelo,J.S.; Cabello,P.H.; Dutra,M.G..
A simple model is proposed, using the method of maximum likelihood to estimate malformation frequencies in racial groups based on data obtained from hospital services. This model uses the proportions of racial admixture, and the observed malformation frequency. It was applied to two defects: postaxial polydactyly and cleft lip, the frequencies of which are recognizedly heterogeneous among racial groups. The frequencies estimated in each racial group were those expected for these malformations, which proves the applicability of the method.
Tipo: Info:eu-repo/semantics/article Palavras-chave: Congenital malformation; Racially mixed populations.
Ano: 1996 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84551996000400024
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Absence of the E2 allele of apolipoprotein in Amerindians Braz. J. Genet.
Marin,Guilherme B.; Tavella,Marli H.; Guerreiro,João F.; Santos,Sidney E.B.; Zago,Marco A..
Determination of the ApoE allele distribution in five South American Amerindian tribes revealed absence of the ApoE2 allele, accompanied by high ApoE3 and low ApoE4 allele frequencies for most tribes, a distribution only previously reported for the Inuit Eskimo from Greenland.
Tipo: Info:eu-repo/semantics/other
Ano: 1997 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84551997000400029
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Alternative procedures for parent choice in a breeding program for the common bean (Phaseolus vulgaris L.) Braz. J. Genet.
Oliveira,L.B.; Ramalho,M.A.P.; Abreu,A. de F.B.; Ferreira,D.F..
Six common bean cultivars were crossed in diallel and the segregant populations were assessed in the F2 and F3 generations to compare methodologies for parental selection in a breeding program based on hybridization. The cultivars involved in the diallel were A 114, A 77, ESAL 686, Milionário, Carioca, and Flor de Mayo. The segregant F2 and F3 generations were assessed on the experimental campus of the Universidade Federal de Larvas, in July 1994. It was found that the cultivars differed in their general combining ability (GCA). Flor de Mayo, which belongs to the Durango race, had the largest positive GCA estimate for grain field, and the cultivars from the Mesoamerican race, Milionário and A 114, the smallest GCA estimates. For flowering, the cultivar...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Breeding program; Common bean.
Ano: 1996 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84551996000400014
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Brains and guts in human evolution: The Expensive Tissue Hypothesis Braz. J. Genet.
The brain is a very expensive organ in metabolic terms. Each unit of brain tissue requires over 22 times the amount of metabolic energy as an equivalent unit of muscle tissue. There is no correlation across mammals, however, between the relative size of the brain and the relative basal metabolic rate. The Expensive Tissue Hypothesis explains this apparent paradox by looking at the metabolic cost of the brain in the context of the costs of other metabolically expensive organs in the body. The results show that the increase in brain size in humans is balanced by an equivalent reduction in the size of the gastro-intestinal tract. In other words, the increased energetic demands of a relatively large brain are balanced by the reduced energy demands of a...
Ano: 1997 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84551997000100023
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Calculation of breed direct and maternal genetic fractions and breed specific direct and maternal heterozygosity for crossbreeding data Braz. J. Genet.
Van Vleck,L.D..
Teaching, research, and herd breeding applications may require calculation of breed additive contributions for direct and maternal genetic effects and fractions of heterozygosity associated with breed specific direct and maternal heterosis effects. These coefficients can be obtained from the first NB rows of a pseudo numerator relationship matrix where the first NB rows represent fractional contributions by breed to each animal or group representing a specific breed cross. The table begins with an NB x NB identity matrix representing pure breeds. Initial animals or representative crosses must be purebreds or two-breed crosses. Parents of initial purebreds are represented by the corresponding column and initial two-breed cross progeny by the two...
Tipo: Info:eu-repo/semantics/article
Ano: 1997 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84551997000400013
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Callus induction and plant regeneration by Brazilian triticale and wheat genotypes Braz. J. Genet.
In order to determine the in vitro behavior of Brazilian triticale, 16 triticale genotypes, and three wheat genotypes used as checks, were sown in June 1994. The explants used were immature embryos. In addition to the genotype tests, two culture media for callus induction were also evaluated, i.e., MS (Murashige and Skoog, Physiol. Plant. 15: 473-497, 1962) medium containing 2.0 mg 2,4D/l, and MS medium containing 4.0 mg 2,4D/l. The plant regeneration protocol used was the one employed at the Laboratório de Cultura de Tecidos, Departamento de Plantas de Lavoura, Universidade Federal do Rio Grande do Sul, for wheat. Differences in plant regeneration were observed both among triticale and wheat genotypes, with triticale usually showing better regeneration...
Tipo: Info:eu-repo/semantics/other
Ano: 1997 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84551997000100008
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Changes in N2 fixation in Stylosanthes scabra derived from tissue culture Braz. J. Genet.
Valarini,Maria José; Otsuk,Ivani Pozar; Vieira,Maria Lucia Carneiro.
Plants were regenerated from leaf-derived callus culture of Stylosanthes scabra, a polyploid legume tolerant to drought and adapted to acid soils. A total of 168 regenerants were planted out in Leonard jars in a complete randomized design. Nitrogen fixation and vegetative growth were indirectly evaluated by shoot dry weight, root dry weight, shoot N content and acetylene reduction activity. The results showed higher variation in the regenerants than in controls not submitted to tissue culture. Significant differences were found for all nitrogen fixation related-traits
Tipo: Info:eu-repo/semantics/other
Ano: 1997 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84551997000400025
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Chromosomal evolution and comparative gene mapping in the Drosophila repleta species group Braz. J. Genet.
Ruiz,Alfredo; Ranz,José María; Cáceres,Mario; Segarra,Carmen.
A review of our recent work on the cromosomal evolution of the Drosophila repleta species group is presented. Most studies have focused on the buzzatii species complex, a monophyletic set of 12 species which inhabit the deserts of South America and the West Indies. A statistical analysis of the length and breakpoint distribution of the 86 paracentric inversions observed in this complex has shown that inversion length is a selected trait. Rare inversions are usually small while evolutionary successful inversions, fixed and polymorphic, are predominantly of medium size. There is also a negative correlation between length and number of inversions per species. Finally, the distribution of inversion breakpoints along chromosome 2 is non-random, with chromosomal...
Tipo: Info:eu-repo/semantics/article
Ano: 1997 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84551997000400003
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Chromosomal polymorphism in urban populations of Drosophila paulistorum Braz. J. Genet.
Valiati,Victor Hugo; Valente,Vera Lucia S..
Drosophila paulistorum populations colonizing the urban area of Porto Alegre, southern Brazil, were studied with the objective of characterizing their chromosomal polymorphism in this new environment. Despite being geographically and ecologically marginal and the fact that the colonization of the urban area seems to be a recent event, the populations showed a large number of inversions on all chromosome arms. Differences regarding inversion frequencies and percentage of heterozygosis were found when we compared the samples with respect to geographical, microenvironmental and temporal aspects. Such differences, however, could be attributed to both selective and stochastic factors
Tipo: Info:eu-repo/semantics/article
Ano: 1997 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84551997000400004
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Chromosome damage in underground coal miners: detection by conventional cytogenetic techniques and by submitting lymphocytes of unexposed individuals to plasma from at-risk groups Braz. J. Genet.
Agostini,J.M.S.; Otto,P.A.; Wajntal,A..
Chromosome abnormalities and the mitotic index in lymphocyte cultures and micronuclei in buccal mucosa cells were investigated in a sample of underground mineral coal miners from Southern Brazil. A decreased mitotic index, an excess of micronuclei and a higher frequency of chromosome abnormalities (fragments, polyploidy and overall chromosome alterations) were observed in the miners when compared to age-paired normal controls from the same area. An alternative assay for clastogenesis in occupational exposition was tested by submitting lymphocytes from non-exposed individuals to a pool of plasmas from the exposed population. This assay proved to be very convenient, as the lymphocytes obtained from the same individuals can be used as target as well as...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Chromosome damage; Underground coal miners; Cytogenetic; Lymphocytes; Plasma; At-risk groups.
Ano: 1996 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84551996000400021
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Chromosome number and secondary constriction variation in 51 accessions of a citrus germplasm bank Braz. J. Genet.
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
Ano: 1997 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84551997000300021
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Chromosome number in germplasm accessions of Paspalum notatum (Gramineae) Braz. J. Genet.
Chromosome numbers are reported for 127 germplasm accessions of Paspalum notatum maintained by EMBRAPA (Empresa Brasileira de Pesquisa Agropecuária) in two research centers in Brazil. Most accessions were collected in their natural habitats in Southern Brazil. Tetraploidy (2n = 40 chromosomes) was predominant (91% of the accessions studied), confirming previous reports for the species. Eleven accessions with 2n = 20 chromosomes, although collected in the wild, are possibly derived from 'Pensacola' bahiagrass, commonly cultivated in the area since its introduction from the United States in the 60's, for the establishment of permanent pastures.
Tipo: Info:eu-repo/semantics/other
Ano: 1997 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84551997000100006
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Chromosome polymorphism in Ctenomys minutus (Rodentia-Octodontidae) Braz. J. Genet.
A sample of 101 specimens of Ctenomys minutus was collected along its geographic range. Eight karyotypes (2n = 42, 45, 46a, 46b, 47, 48, 49 and 50) were found. The chromosome polymorphisms were due to Robertsonian rearrangements and tandem fusions. The distribution of polymorphisms indicated three population blocks: northern (2n = 49 and 50), central (2n = 46a, 47, and 48) and southern (2n = 42, 45, and 46b). These findings suggest that this species is undergoing a speciation process due to geographic isolation.
Tipo: Info:eu-repo/semantics/other
Ano: 1997 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84551997000100001
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Chromosome sensitivity to bleomycin in G2 lymphocytes from Down syndrome patients Braz. J. Genet.
Several studies have demonstrated that lymphocytes from patients with Down syndrome (DS) exhibit an increased frequency of chromosome aberrations when they are exposed to ionizing radiation or to chemicals at the G0 or G1 phases of the cell cycle, but not at G2, when compared to normal subjects. To determine the susceptibility of DS lymphocytes at G2 phase, bleomycin, a radiomimetic agent, was used to induce DNA breaks in blood cultures from 24 Down syndrome patients. All the patients with DS showed free trisomy 21 (47,XX + 21 or 47,XY + 21). Individuals that showed an average number of chromatid breaks per cell higher than 0.8 were considered sensitive to the drug. No control child showed susceptibility to bleomycin, and among the 24 patients with DS,...
Tipo: Info:eu-repo/semantics/other
Ano: 1997 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84551997000100015
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Chromosome studies in some Stevia. Cav. (Compositae) species from Southern Brazil Braz. J. Genet.
Frederico,Adriana P.; Ruas,Paulo M.; Marin-Morales,Maria A.; Ruas,Claudete F.; Nakajima,Jimi N..
Karyotypes of six species of the genus Stevia from Southern Brazil were studied, utilizing root tip metaphases. All species were diploid with 2n = 22 chromosomes. It was possible to identify each species by chromosome morphology. The basic chromosome number for Brazilian species of Stevia is X = 11. This number is also found in almost all South American species. We suggest that in Stevia there is an evolutionary trend toward chromosomal rearrangement, caused mainly by pericentric inversions. It was found that, in addition to aneuploidy and polyploidy, chromosomal rearrangements are common in the tribe Eupatorieae.
Tipo: Info:eu-repo/semantics/article Palavras-chave: Chromosome; Stevia. Cav.; Southern Brazil.
Ano: 1996 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84551996000400013
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Chromosome studies in southern Brazilian wheat pest aphids Sitobion avenae, Schizaphis graminum, and Methopolophium dirhodum (Homoptera: Aphididae) Braz. J. Genet.
Celis,Verónica E. Rubín de; Gassen,Dirceu N.; Santos-Colares,Marisa C.; Oliveira,Alice K.; Valente,Vera L.S..
We examined the chromosome set of the aphid species Sitobion avenae, Schizaphis graminum and Methopolophium dirhodum by means of conventional staining and C, NOR, AluI and HaeIII banding methods. These species are considered important pests to several plants of economic interest in Brazil. No variation was observed in the number of chromosomes of S. avenae, whereas there was intraspecific variation in the other two species. Interspecific differences in the response to the banding treatments were observed. Whereas these techniques allowed the identification of several S. graminum chromosome pairs, only the AluI treatment was capable of inducing differential staining in the M. dirhodum chromosomes and no clear patterns emerged when the S. avenae preparations...
Tipo: Info:eu-repo/semantics/article
Ano: 1997 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84551997000300010
Registros recuperados: 109
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