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| Registros recuperados: 6,708 | |
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| Morais Jr.,M.A.; Vlcková,V.; Fridrichová,I.; Slaninová,M.; Brozmanová,J.; Henriques,J.A.P.. |
| Molecular and functional homology between yeast proteins pRad51 and pRad52 and Escherichia coli pRecA involved in recombinational DNA repair led us to investigate possible effects of recA gene expression on DNA repair in rad51 and rad52 mutants of Saccharomyces cerevisiae. The mutant cells were subjected to one of the following treatments: preincubation with 8-methoxypsoralen and subsequent irradiation with 360-nm ultraviolet (UVA) (8-MOP + UVA), irradiation with 254-nm UV light or treatment with methyl methane sulfonate (MMS). While recA expression did not repair lethal DNA lesions in mutant rad51, it was able to partially restore resistance to 8-MOP + UVA and MMS in rad52. Expression of recA could not complement the sensitivity of rad51rad52 double... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1998 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47571998000100002 |
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| Tuan,Roseli; Simões,Luiz Carlos Gomes. |
| Biomphalaria tenagophila is a simultaneous hermaphrodite freshwater snail, which can breed by self and cross-fertilization. It is, therefore, well suited for studying reproduction as an evolutive strategy. Several characteristics (shell size and age at sexual maturity, egg fecundity and fertility) were analyzed in four consecutive self-fertilized generations and compared to cross-fertilized individuals. The reproductive parameters were similar in the two groups. Shell size was significantly greater in the fourth self-fertilized generation than in the cross-fertilized individuals. |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1998 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47571998000400012 |
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| Miranda,Zilda F.S.; Arias,Carlos A. Arrabal; Toledo,José Francisco Ferraz de; Oliveira,Marcelo Fernandes de. |
| The oil content of soybean (Glycine max (L.) Merrill) seeds is a polygenic and complex trait that is responsive to environmental effects that occur during plant development. Our objective was to study the seed oil content of soybeans developed under diverse photoperiod and temperature conditions. Three parental inbred lines with classic (BR-13, FT-2 and BR85-29009) and one with long juvenile flowering type (OCEPAR 8) and the F2, F3, and F9 generations derived from all possible crosses between them (including reciprocals) were sowed in September 27th, October 20th and December 17th in 1993 in Londrina, Paraná State, Brazil (between 23o08'47" and 23o55'46" latitude S). The October and December sowing dates are within the period the varietal research... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1998 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47571998000300017 |
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| Montalván,Ricardo; Ando,Akihiko; Echeverrigaray,Sérgio. |
| Grain proteins from 58 Brazilian and nine Japanese upland rice cultivars (Oryza sativa L.) were electrophoretically separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Densitometric scanning of the electrophoretic profiles permitted the estimation of the relative concentration of 16 protein fractions, which were used as variables for the calculation of Fisher's canonical discriminating functions. Significant differences between mean values of protein fractions were useful in distinguishing Brazilian and Japanese cultivars, as well as improved and non-improved Brazilian rice cultivars in scattered plots. Electrophoretically detectable protein polymorphism in rice grain can indicate geographic origin as well as breeding... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1998 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47571998000400021 |
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| Colombo,Carlos; Second,Gérard; Valle,Tereza Losada; Charrier,André. |
| RAPD markers were used to investigate the genetic diversity of 31 Brazilian cassava clones. The results were compared with the genetic diversity revealed by botanical descriptors. Both sets of variates revealed identical relationships among the cultivars. Multivariate analysis of genetic similarities placed genotypes destinated for consumption "in nature" in one group, and cultivars useful for flour production in another. Brazils abundance of landraces presents a broad dispersion and is consequently an important resource of genetic variability. The botanical descriptors were not able to differentiate thirteen pairs of cultivars compared two-by-two, while only one was not differentiated by RAPD markers. These results showed the power of RAPD markers over... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1998 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47571998000100018 |
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| Penna,Julio C. Viglioni; Verhalen,Laval M.; Kirkham,M.B.; McNew,Ronald W.. |
| The objectives of this study were to adapt a screening method previously used to assess seedling drought tolerance in cereals for use in cotton (Gossypium hirsutum L.) and to identify tolerant accessions among a wide range of genotypes. Ninety genotypes were screened in seven growth chamber experiments. Fifteen-day-old seedlings were subjected to four 4-day drought cycles, and plant survival was evaluated after each cycle. Three cycles are probably the minimum required in cotton work. Significant differences (at the 0.05 level or lower) among entries were obtained in four of the seven experiments. A "confirmation test" with entries previously evaluated as "tolerant" (high survival) and "susceptible" (low survival) was run. A number of entries duplicated... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1998 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47571998000400023 |
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| Gava,A.; Freitas,T.R.O.; Olimpio,J.. |
| Intraspecific karyotype variation in mammal species is very common and often caused by centromeric fusion of acrocentric chromosomes. We describe here a new karyotype 2n = 62 (FN = 112) for the genus Cavia from the Moleques do Sul Islands, of the southern coast of Brazil. We analyzed two male and four female karyotypes that had twenty-four biarmed pairs and six pairs of acrocentric chromosomes. The sexual pair consisted of a metacentric X-chromosome and a large acrocentric Y. C-bands were found in the centromeric and pericentromeric regions of almost all chromosomes, except for some small biarmed and acrocentric ones. Nucleolus organizer regions appeared in two biarmed chromosomes, and G-banding patterns were also seen. |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1998 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47571998000100013 |
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| Simioni,Carine; Schifino-Wittmann,Maria Teresa; Paim,Nilton Rodrigues. |
| A population of 513 hybrids of Leucaena leucocephala (4x) and L. diversifolia ssp. diversifolia (4x), that is being analyzed for several morphological and agronomical characteristics, aiming at selecting cold tolerant plants, was also analyzed for floral color. A model of additive dominant inheritance (pink color dominant over white color, or presence versus absence of pigment, and the number of dominant alleles present determining the intensity of the pink color) is proposed. The action of two independent locus sets is also suggested, one for the male (with two main structural genes) and another for the female floral organs (one main structural gene). It is suggested that an undetermined number of regulatory genes affect color expression. |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1998 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47571998000300013 |
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| Martins,Cesar; Galetti Jr.,Pedro Manoel. |
| Fish of the neotropical family Anostomidae generally show low karyotype variability. Nevertheless, karyotype variants have been identified within some genera, providing information about their evolutionary history. Species of the genus Schizodon show a high degree of morphological and ecological similarity compared to other anostomids. In the present study, karyotype characteristics of Schizodon borelli (40 individuals) and S. isognathum (one individual), two sympatric species found in the Paraguay River basin, were studied. C-banding, GC-specific fluorochrome Mitramycin (MM) and Ag staining as well as in situ hybridization (FISH) with rDNA probes were used. The karyotypes of these species were found to be very similar. Only two NORs were detected in a... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1998 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47571998000300011 |
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| Drets,Máximo E.; Mendizábal,Marcos. |
| Microphotometrical scanning and computer graphic image analysis were carried out to detect the distribution of chromatin densities in subtelomeric segments of T-banded endoreduplicated chromosomes of Chinese hamster ovary (CHO) cells. Chromatin density patterns detected with this method were similar to those previously found in CHO and normal human chromosomes. The highest chromatin densities were considered as marker segments which led to the detection of reciprocal changes of position in endoreduplicated chromosomes during cell spreading on the slide. The problem of the subtelomeric T-banding density patterns found in the endoreduplicated chromosomes and their relation to the structure and molecular composition of this region is briefly discussed. |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1998 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47571998000200008 |
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| Sousa,João Alencar de; Maluf,Wilson Roberto. |
| This study was carried out to obtain estimates of heterosis in crosses between seven eggplant cultivars (Embu = E; Santa Genebra = SG; Viserba = V; Aubergine de Barbentane = AB; Florida Market 10 = FM; Black Beauty = BB, and Melitino = M) and two breeding lines (B-14-07 = B1 and B-31-06 = B2). The F1 hybrids used were: E x FM; E x BB; E x M; E x B1; E x B2; SG x FM; SG x BB; SG x M; SG x B1; SG x B2; V x FM; V x B1; V x B2; AB x FM; AB x M; AB x B1; AB x B2 and M x FM. Cultivars, lines and hybrids were evaluated at the ESAL experimental field in Lavras, MG, from February to October 1992. A randomized complete block design with three replications was used. Significant heterosis relative to the parental means was detected for all traits studied. Their values... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1998 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47571998000100017 |
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| Azevedo,Diógenes Manoel Pedroza de; Crisóstomo,João Ribeiro; Almeida,Francisco Célio Guedes; Rossetti,Adroaldo Guimarães. |
| The present study estimates variances and genetic and phenotypic correlations for five traits in 27 progenies of cashew trees (Anacardium occidentale L.). Data were obtained from a trial conducted in 1992 at Pacajus, Ceará, experimental station of Embrapa Agroindústria Tropical. The characters studied were plant height (PH), North-South and East-West canopy spreads (NSS, EWS), and primary and secondary branch numbers (PBN, SBN). All genetic and phenotypic correlations presented positive and significant values. Selection to increase or decrease the average of any one of the five characteristics of cashew plants in the progenies studied affected the average of the others. The 16-month-old canopy spread can be predicted from NSS or EWS since correlations... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1998 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47571998000300019 |
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| Cuco,Silvia Marina; Bandel,Gerhard. |
| Flowers of three Hevea brasiliensis clones, RRIM 527, RRIM 600 and GT 1, were analyzed under stereomicroscope and scanning electron microscope, aiming to observe hermaphroditism rates. Results showed 71.49% hermaphrodite flowers, 29.83% of which exhibited incompletely developed, residual anthers. The scanning electron microscope analysis did not detect differences in anther epidermis of male and bisexual flowers of RRIM 600 and RRIM 527. In GT 1 clone (sterile male), the anther epidermis was already weak at the beginning of floral development and completely wrinkled at the end of maturation. Consequently, the anthers were empty by this stage. |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1998 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47571998000400019 |
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| Gonçalves,Paulo de Souza; Bataglia,Ondino Cleante; Santos,Wagner Rodrigues dos; Ortolani,Altino Aldo; Segnini Jr.,Ivo; Shikasho,Edson Hideaki. |
| Budwood from seven different clones of rubber tree [Hevea brasiliensis (Willd. ex Adr. de Juss.) Müell. Arg.] was planted in replicated trials in four different test sites in the plateau region of the state of São Paulo, Brazil. The clones represented a range of imported germplasm, whereas the locations were selected to represent a range of rubber growing areas. Girths were measured for six years consecutively, before the initiation of tapping for latex. Total number of latex vessel rings (lvr) and bark thickness (bt) were measured at six years. The largest average for all characters was observed in Matão. Overall means for girth, total number of latex vessel rings and bark thickness at six years were 35.26 cm, 11.30 units and 4.83 mm, respectively. Both... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1998 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47571998000100019 |
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| Mota,Lígia Souza Lima Silveira da; Silva,Rosana Ap. Bicudo da. |
| Nine phenotypically normal Saanen goats (6 males and 3 females) belonging to the goat house of the Instituto de Biociências, UNESP, Botucatu Campus, were analyzed cytogenetically. The objective of the present study was to determine whether or not chromosomes 5 and 15 are involved in a Robertsonian translocation previously observed in a sample of a Brazilian herd using the chromosome pattern described by the ISCNDA (1989). The results suggest the involvement of chromosomes 6 and 15 in the fusion demonstrated by G-banding in prometaphase cells. The Brazilian sample of animals carrying structural rearrangements did not present any reduction in fertility, suggesting the existence of prezygotic selection against unbalanced gametes. Further investigations on the... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1998 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47571998000100012 |
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| Hatanaka,Terumi; Tambasco,Antonio Junqueira; Galetti Junior,Pedro Manoel. |
| Few cytogenetic studies have been conducted on South American canids. Cerdocyon thous is a representative of the Canidae, living in the forests, open wooded areas and savannahs of South America. Compared to other canid species, C. thous has a large proportion of metacentric and submetacentric chromosomes as well as a large amount of constitutive heterochromatin, especially along the short arm of submetacentric chromosomes. In the present study, different chromosome banding methods were used to characterize the heterogeneous nature of the large heterochromatic segments and to propose an organizational model for this segment that occupies the entire short arm of most two-armed chromosomes. Furthermore, chromosome heteromorphism related to the short arm of... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1998 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47571998000200009 |
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| Rafael,Míriam Silva; Tadei,Wanderli Pedro. |
| Metaphase karyotypes of Anopheles (Nyssorhynchus) darlingi and Anopheles (N.) nuneztovari from Manaus and Highway BR-174 (Manaus-Boa Vista), State of Amazonas, and Macapá, State of Amapá, Brazil, showed 2n = 6. They consisted of a pair of metacentric (chromosome II) and a pair of submetacentric (chromosome III) autosomes as well as sex chromosomes X and Y. In the sex chromosomes, the X was acrocentric in A. darlingi and submetacentric in A. nuneztovari. The Y chromosome was pointed in both species. The chromosomes of A. nuneztovari were larger than those of A. darlingi except for the Y chromosome. A. nuneztovari showed size polymorphism in the X chromosome. Somatic pairing and a strong constriction around the centromeric region in chromosomes II and III... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1998 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47571998000300010 |
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| Registros recuperados: 6,708 | |
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