bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic distances and taxonomic trees between goats of Ceará State (Brazil) and goats of the Mediterranean region (Europe and Africa)
Authors: Machado Théa M.M. , Chakir Mohamed , Lauvergne Jean Jacques
Published: April 2005

Goats of an undefined breed (called UDB) from the State of Ceará, northeastern Brazil (N = 447), European Mediterranean goats (N = 3,847) and African Mediterranean goats (N = 325) were compared to establish genetic distances and taxonomic trees. Allelic frequencies in each population for presence or absence of the following traits were used: horns, reduced ears, long hair, wattles, beard, roan color, brown eumelanin and eumelanic standard pigmentation. The genetic distance, applying the method developed by Nei (1972), was: least between goats from different meso-regions of the State of Ceará (0.0008 to 0.0120); small between all UDB of Ceará and French goats of Rove and Haute Roya (0.0236 and 0.0459); greater between all UDB of Ceará and northern Spanish goats (0.1166), and greatest between all UDB of Ceará and northern African goats (Moroccan of Drâa, Rhâali and Zagora), Balkan goats (Sakhar from Bulgaria and Macedonia from Greece) and some insular Mediterranean populations (Corsica, Sicily and Sardinia), which ranged from 0.1237 to 0.2714. Brazilian UDB goats are more closely related to Continental and Western European populations than to North African, Balkan or Insular Mediterranean populations.
A second case of multivalent meiotic configurations in diploid species of Anura
Authors: Lourenço Luciana Bolsoni , Recco-Pimentel Shirlei M. , Cardoso Adão José
Published: April 2005

We analyzed the meiotic chromosomes of specimens from the two karyological groups of Physalaemus petersi (Jiménez de la Espada, 1872) described in the literature. Multivalent configurations (rings or chains) were observed in both groups. This meiotic organization resulted from the terminal association of non-homologous chromosomes, and an analysis of C-banded multivalents indicated no involvement of heterochromatic regions in these associations. A possible explanation for such meiotic configurations is the occurrence of heterozygous translocations. Thus, multivalents may indicate the involvement of translocation events in the karyotypic evolution of P. petersi.
Mapping 18S ribosomal genes in fish of the genus Brycon (Characidae) by fluorescence in situ hybridization (FISH)
Authors: Wasko Adriane Pinto , Galetti Jr. Pedro Manoel
Published: April 2005

The present study provides data on the nucleolar organizer regions (NORs) of seven Brycon species based on mapping of the 18S rRNA genes by fluorescence in situ hybridization (FISH). Fluorescent signals were observed on the telomere of the long arm of two large submetacentric chromosomes, thus confirming the number and location of NORs previously revealed by other classical cytogenetic techniques. Although there were no inter- or intra-individual variations in the number and location of the 18S loci, NOR size polymorphism was observed between homologous chromosomes. The clustering and conservation of NORs in a single chromosome pair indicates a high level of NOR stability among species of the genus Brycon.
Lactate dehydrogenase of Mugil sp. (Mugilidae, Perciformes). Lack of electrokinetic, thermostability and kinetic differences among individuals with different number of scales
Authors: Santos Marcelo dos , Schwantes Maria Luiza B. , Schwantes Arno Rudi
Published: April 2005

The scale number in lateral sets (SNS) of Mugil sp. (Mugilidae, Perciformes) collected in the lagoon-estuarine region of Cananéia, State of São Paulo ranges from 33 to 39. Electrokinetic, kinetic and thermostability properties of lactate dehydrogenase (LDH) were tested to determine if individuals with different SNS correspond to different species or populations of mullet. As in many other teleosts, LDH-A*, LDH-B*, and LDH-C* loci were detected. Through a two-fold serial dilution method applied to 10 different tissues of Mugil sp., a bidirectionally divergent expression of these loci was suggested. No association among LDH electrophoretic pattern, thermal inactivation, kinetic responses and different SNS was observed. The apparent Km (pyr) values obtained here were similar to Km values obtained by other authors for muscle and heart LDH or their purified isoforms. The effect of NaCl on Km and Vmax values of Mugil sp. (35 and 39 SNS individuals) indicates that this salt behaves as a competitive inhibitor, since it decreases enzyme-substrate affinity. Thus, electrokinetic and thermostability behavior, Km and Vmax values and the effect of NaCl do not permit us to consider these mullets, with SNS ranging from 33 to 39, as belonging to different populations or species.
The use of random amplified polymorphic DNA to evaluate the genetic variability of Ponkan mandarin (Citrus reticulata Blanco) accessions
Authors: Coletta Filho Helvécio Della , Machado Marcos Antonio , Targon M. Luiza P.N. , Pompeu Jr. Jorgino
Published: April 2005

RAPD analysis of 19 Ponkan mandarin accessions was performed using 25 random primers. Of 112 amplification products selected, only 32 were polymorphic across five accessions. The absence of genetic variability among the other 14 accessions suggested that they were either clonal propagations with different local names, or that they had undetectable genetic variability, such as point mutations which cannot be detected by RAPD.
Diversity within American cassava germ plasm based on RAPD markers
Authors: Colombo Carlos , Second Gérard , Charrier André
Published: April 2005

This work focuses on the genetic diversity of American cassava through RAPD molecular markers. The 126 genotypes studied were distributed on four geographical levels ranging from local to continental. Samples included ethnocultivars from the Santa Isabel community in the Brazilian Amazon, local cultivars collected in the State of São Paulo, native accessions from very diverse Brazilian regions, and representative accessions from the Centro Internacional de Agricultura Tropical (CIAT) core collection. Eighty-eight polymorphic bands were analyzed. Results revealed the weak genetic structure of the cassava analyzed. The pattern formed by the first two axes of the principal coordinates analysis (PCoA) revealed an overlapping of the São Paulo State genotype, the Brazilian group and the core collection accessions. The Santa Isabel ethnocultures formed a separate group. The weak genetic structure of cassava can be explained by the common practice of exchanging botanical material among small producers as well as by recombinations among genotypes. When the genotypes were analyzed using climatic data, the sample sites were found to be structured according to temperature and precipitation. RAPD markers proved very useful in the genetic diversity study, resulting in important implications for cassava germ plasm collections and genetic breeding.
Wild cassava, Manihot spp.: Biology and potentialities for genetic improvement
Authors: Nassar Nagib M.A.
Published: April 2005

Wild species of Manihot are progenitors of cassava. They constitute valuable genetic reservoirs presenting genes that show new characters. Screening of these species showed some of them to have a notably high percentage of protein combined with a low percentage of hydrocyanic acid. Study of natural habitats revealed resistance to drought and excessive soil aluminum toxicity as well as adaptation to low temperature. Some of the hybrids obtained showed high root productivity and resistance to stem borers. Apomixis was discovered in the wild and transferred successfully to the cultivate species.
Proportional odds model applied to mapping of disease resistance genes in plants
Authors: Spyrides-Cunha Maria Helena , Demétrio Clarice G.B. , Camargo Luis E.A.
Published: April 2005

Molecular markers have been used extensively to map quantitative trait loci (QTL) controlling disease resistance in plants. Mapping is usually done by establishing a statistical association between molecular marker genotypes and quantitative variations in disease resistance. However, most statistical approaches require a continuous distribution of the response variable, a requirement not always met since evaluation of disease resistance is often done using visual ratings based on an ordinal scale of disease severity. This paper discusses the application of the proportional odds model to the mapping of disease resistance genes in plants amenable to expression as ordinal data. The model was used to map two resistance QTL of maize to Puccinia sorghi. The microsatellite markers bngl166 and bngl669, located on chromosomes 2 and 8, respectively, were used to genotype F2 individuals from a segregating population. Genotypes at each marker locus were then compared by assessing disease severity in F3 plants derived from the selfing of each genotyped F2 plant based on an ordinal scale severity. The residual deviance and the chi-square score statistic indicated a good fit of the model to the data and the odds had a constant proportionality at each threshold. Single-marker analyses detected significant differences among marker genotypes at both marker loci, indicating that these markers were linked to disease resistance QTL. The inclusion of the interaction term after single-marker analysis provided strong evidence of an epistatic interaction between the two QTL. These results indicate that the proportional odds model can be used as an alternative to traditional methods in cases where the response variable consists of an ordinal scale, thus eliminating the problems of heterocedasticity, non-linearity, and the non-normality of residuals often associated with this type of data.
Analysis of variance of partial diallel tables
Authors: Viana José Marcelo Soriano , Cruz Cosme Damião , Cardoso Antonio Américo , Regazzi Adair José
Published: April 2005

The theory of variance analysis of partial diallel tables, following Hayman's proposal of 1954, is presented. As several statistical tests yield similar inferences, the present analysis mainly proposes to assess genetic variability in two groups of parents and to study specific, varietal and mean heteroses. Testing the nullity of specific heteroses equals testing absence of dominance. Testing equality of varietal heteroses of the parents of a group is equivalent to testing the hypothesis that in the other group allelic genes have the same frequency. Rejection of the hypothesis that the mean heterosis is null indicates dominance. The information obtained complements that provided by diallel analysis involving parents and their F1 hybrids or F2 generations. An example with the common bean is included.
Variability in micronucleus induction with different mutagens applied to several species of fish
Authors: Grisolia Cesar Koppe , Cordeiro Célia Maria Torres
Published: April 2005

Fish are often used for screening genotoxicity of water. For such programs, a knowledge of the sensitivity to clastogens, spontaneous micronucleus frequency and cell cycle kinetics of the target tissue is necessary. To investigate the pattern of inter-specific sensitivity to micronucleus induction three species of fish, Tilapia rendalli, Oreochromis niloticus and Cyprinus carpio, were exposed to the clastogens bleomycin (BLM), cyclophosphamide (CP), 5-fluorouracil (5-FU), and mitomycin C (MMC). The binucleate/mononucleate ratio in peripheral erythrocytes exposed to cytochalasin B was also used to evaluate the time-dependent response of micronucleus formation during hematopoesis in the kidney and the micronucleus peak in peripheral erythrocytes. Micronucleus frequencies induced by CP were significantly greater than their respective controls for the three fish species throughout all treatment periods. During the whole evaluation period (30 days) CP was also the most effective clastogen. In general, until the 14th day of evaluation period T. rendalii was the most sensitive species to clastogens. No difference in micronucleus frequencies among species was observed in the 4th evaluation (at the 30th day). A micronucleus peak was observed at the 7th day after treatment. After the 14th day the frequencies were stabilized. The cytochalasin B experiment was carried out to demonstrate that micronuclei induced in the young kidney erythrocyte cells were detected in the circulating blood 2-4 days later.
Barber-Say syndrome: further delineation of the clinical spectrum
Authors: Cortés Fanny M. , Troncoso Ledia A. , Alliende Angélica R. , Curotto Bianca L.
Published: April 2005

We report on a 14-year-old girl who presented a multiple congenital anomaly pattern: ablepharon, hypertelorism, telecanthus, macrostomia, helix agenesis of both ears, redundant thick skin and severe hirsutism, the 5th reported case of Barber-Say syndrome. Our patient had almost the same phenotype as that of the patient cited by Martínez Santana et al. (Am. J. Med. Genet. 47: 20-23, 1993) including the same until then undescribed dermatoglyphic pattern.
Population structure and morphometric variance of the Apis mellifera scutellata group of honeybees in Africa
Authors: Radloff Sarah , Hepburn Randall
Published: April 2005

The honeybee populations of Africa classified as Apis mellifera scutellata Lepeletier were analysed morphometrically using multivariate statistical techniques. The collection consisted of nearly 15,000 worker honeybees from 825 individual colonies at 193 localities in east Africa, extending from South Africa to Ethiopia. Factor analysis established one primary cluster, designated as A. m. scutellata. Morphocluster formation and inclusivity (correct classification) are highly sensitive to sampling distance intervals. Within the A. m. scutellata region are larger bees associated with high altitudes of mountain systems which are traditionally classified as A. m. monticola Smith, but it is evident that these bees do not form a uniform group. Variance characteristics of the morphometric measurements show domains of significantly different local populations. These high variance populations mostly occur at transitional edges of major climatic and vegetational zones, and sometimes with more localised discontinuities in temperature. It is also now evident that those A. m. scutellata introduced nearly fifty years ago into the Neotropics were a particularly homogenous sample, which exhibited all the traits expected in a founder effect or bottleneck population.
Highly polymorphic DNA markers in an Africanized honey bee population in Costa Rica
Authors: Lobo Segura Jorge Arturo
Published: April 2005

Two genetic markers (the mtDNA COI-COII intergenic region and the microsatellite A7) with high levels of variability in South African and European honey bees were analyzed in wild swarms of Africanized honey bees (Apis mellifera) from Costa Rica. Allelic or haplotypic frequencies revealed high levels of genetic variability at these loci in this population. Most of the alleles were African alleles, although some European-derived alleles were also present. Differences in the frequencies of African alleles between African and Africanized samples were minor, which could be explained by founder effects occurring during the introduction of African honey bee populations into South America.
A putative resistant DNA marker for wool yellowing susceptibility in sheep
Authors: Benavides M.V. , Damak S. , Maher A.P.
Published: April 2005

An Australian Merino flock was screened for low (resistant) and high (susceptible) yellow predictive colour (YPC) breeding values in order to compare extreme individuals using the differential display of mRNA technique. One differentially expressed cDNA band was visualised only in the resistant group. This band showed no identity with the DNA sequences of public databases; however, they showed short homologies with three database sequences related to transmembrane signalling functions. The use of these candidate genes as DNA markers needs to be confirmed against sheep with a wide range of susceptibility to wool yellowing to verify the results.
Sympatric occurrence of two cytotypes of Astyanax scabripinnis (Characiformes, Characidae)
Authors: Maistro Edson Luis , Oliveira Claudio , Foresti Fausto
Published: April 2005

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 chromosome evolution of Astyanax scabripinnis are discussed.
Isoenzymatic variation in the germplasm of Brazilian races of maize (Zea mays L.)
Authors: Gimenes Marcos Aparecido , Lopes Catalina Romero
Published: April 2005

There are more than 200 races of maize (Zea mays L.) divided into three groups (ancient commercial races, the recent commercial races, and indigenous races). Although the indigenous races have no commercial value, they have many important characteristics which can be incorporated into maize breeding programs. Most Brazilian indigenous germplasm race stocks were collected at least 40 years ago, and nothing is known of the genetic variability present in this germplasm. The genetic variability was assayed in 15 populations from four indigenous races of maize (Caingang, Entrelaçado, Lenha and Moroti) and five indigenous cultivars, using five isoenzymatic systems encoded by 14 loci. The analysis revealed a low level of variability among the samples studied. Overall, the mean number of alleles/polymorphic locus was three, 64.3% of the loci analyzed being polymorphic and the estimated heterozygosity was 0.352. The mean number of alleles/polymorphic locus per population was 1.6. A mean of 47.5% of the loci were polymorphic. The mean expected heterozygosity was 0.195, the mean genetic identity was 0.821 and the proportion of total genetic diversity partitioned among populations (Gst) was 0.156. A founder effect could explain the low variability detected.
Yield stability in maize (Zea mays L.) and correlations among the parameters of the Eberhart and Russell, Lin and Binns and Huehn models
Authors: Scapim Carlos Alberto , Oliveira Valter Rodrigues , Braccini Alessandro de Lucca e , Cruz Cosme Damião , Andrade Carlos Alberto de Bastos , Vidigal Maria Celeste Gonçalves
Published: April 2005

Assessment of the stability and adaptability of a genotype to different environments is useful for recommending cultivars for known conditions of cultivation and should be a requirement in breeding programs. Twenty maize (Zea mays L.) cultivars were tested at eight locations in Minas Gerais by the National Center for Maize and Sorghum Research (CNPMS) of the Brazilian Enterprise for Agricultural Research (EMBRAPA) for two years. The experiments involved a randomized complete block design in which three procedures were used to analyze cultivar stability and adaptability. The level of association among the parameters obtained by the three methods was assessed using Spearman's rank correlation. Hybrids 'DINA 170', 'G-96C', 'C 505', 'DINA 70' and 'C 435' had a mean yield greater than 6,000 kg/ha. Eberhart and Russell's regression coefficient (betai) was negative and correlated significantly (P < 0.01) with Lin and Binn's superiority index (Pi), indicating that the most responsive cultivars tended to have smaller Pi. Pi did not correlate with Huehn's nonparametric measurements Si(2) and Si(3) nor with Eberhart and Russell's sigmadi² (P > or = 0.05), but correlated positively with Si(1) (P < 0.05), indicating that superior genotypes (with lower Pi) could also be stable, a finding not commonly reported in the literature. The stability parameters, Si(1), Si(2), Si(3) and sigmadi², correlated positively among each other (P < 0.01), indicating that the stability estimates of the Huehn's nonparametric model did not add important information to those obtained by the Eberhart and Russell's method. Estimates from the Huehn's method, however, showed that stability estimates from nonparametric models are useful alternatives to parametric models. 'DINA 170', which had a greater general mean, was characterized as a cultivar adapted to favorable environments, and was among the most productive in the different environments assessed. The cultivar 'G-96C' showed medium adaptation to all environments (ideal cultivar) and had good stability. Cultivars 'C 505' and 'C435' were alternatives for 'G-96C'. 'DINA 70' showed good adaptability but had low stability.
Optimization of PCR amplification of maize microsatellite loci
Authors: Ogliari Juliana Bernardi , Boscariol Raquel L. , Camargo Luis E.A.
Published: April 2005

Maize (Zea mays L.) microsatellite loci are useful as genetic markers because they are numerous, occur in every chromosome, and have a high content of polymorphism information. Furthermore, they can be amplified by PCR and the resulting fragments resolved on agarose gels. A major problem, however, is that the primers used in their amplification often have different length and nucleic acid content, requiring optimization of PCR amplification programs for each locus. We developed "touchdown" PCR programs successfully used in the amplification of a set of 125-maize microsatellite loci, chosen as representative of all chromosomes. The programs varied both in relation to the annealing temperature (Tm) and primer concentration. Primers could be divided into four groups. A large group included primers that amplified well in a basic previously published amplification program but with different primer concentrations. A second group amplified in alternative programs in which the annealing temperatures were changed so as to include the Tm of either both primers or the highest Tm of the primer pair estimated based on their nucleotide composition. A third group included primers that amplified in programs with Tm higher than those estimated, and in a fourth group, with just two pairs of primers, the opposite situation prevailed.
Sequence characterization of hypervariable regions in the soybean genome: leucine-rich repeats and simple sequence repeats
Authors: Barros Everaldo G. de , Tingey Scott , Rafalski J. Antoni
Published: April 2005

The genetic basis of cultivated soybean is rather narrow. This observation has been confirmed by analysis of agronomic traits among different genotypes, and more recently by the use of molecular markers. During the construction of an RFLP soybean map (Glycine soja x Glycine max) the two progenitors were analyzed with over 2,000 probes, of which 25% were polymorphic. Among the probes that revealed polymorphisms, a small proportion, about 0.5%, hybridized to regions that were highly polymorphic. Here we report the sequencing and analysis of five of these probes. Three of the five contain segments that encode leucine-rich repeat (LRR) sequence homologous to known disease resistance genes in plants. Two other probes are relatively AT-rich and contain segments of (A)n/(T)n. DNA segments corresponding to one of the probes (A45-10) were amplified from nine soybean genotypes. Partial sequencing of these amplicons suggests that deletions and/or insertions are responsible for the extensive polymorphism observed. We propose that genes encoding LRR proteins and simple sequence repeat region prone to slippage are some of the most hypervariable regions of the soybean genome.
Hordein variation in Brazilian barley varieties (Hordeum vulgare L.) and wild barley (H. euclaston Steud. and H. stenostachys Godr.)
Authors: Echart-Almeida Cinara , Cavalli-Molina Suzana
Published: April 2005

SDS-PAGE was used to analyze the hordein polypeptide patterns of Brazilian barley varieties (Hordeum vulgare L.) and of two native species of Hordeum from southern Brazil (H. euclaston Steud. and H. stenostachys Godr.). Forty different hordein polypeptide bands with molecular weights ranging from 30 to 94 kDa were found in the seeds of the three species studied. Twelve of the 14 varieties examined showed intravarietal polymorphism. The number of bands ranged from 10 to 17, depending on the variety, and from 3 to 13 among individual seeds, with a total of 26 bands in H. vulgare. Phenograms using each seed as an operational taxonomic unit (OTU) showed that the seeds from most varieties did not form distinct clusters. Seeds from different plants of the native species varied considerably. The molecular weights of the hordein polypeptides of the two native species were quite different from those of H. vulgare. There was a greater similarity between the native species than with H. vulgare, although H. stenostachys was slightly closer to the cultivated species than H. euclaston.
Incorporating different proportions of exotic maize germplasm into two adapted populations
Authors: Santos Manoel Xavier dos , Pollak Linda Maria , Pacheco Cleso Antônio Patto , Guimarães Paulo Evaristo Oliveira , Peternelli Luiz Alexandre , Parentoni Sidney Netto , Nass Luciano Lourenço
Published: April 2005

Maize breeders frequently wish to use exotic germplasm in their breeding programs without losing specific characteristics of their adapted material. The objective of this study was to determine the optimal proportions of exotic germplasm to incorporate into adapted populations (F2 = 50% exotic, BC1 = 25% exotic, BC2 = 12.5% exotic and BC3 = 6.25% exotic) to form the initial foundation population and to determine the heterosis between adapted x exotics. We used six exotic populations of different origins and two adapted populations representing a Brazilian heterotic pattern. In 1993-94 and 1994-95, the parents, F1, F2, BC1, BC2, BC3 and four checks were evaluated in six environments in central Brazil using an 8 x 9 simple rectangular lattice design. Higher mean values for yield were obtained as the proportion of exotic germplasm decreased. Some backcrosses produced more than the adapted populations BR 105 (7.59 ton/ha) and BR 106 (8.43 ton/ha). The best results were obtained when incorporating 6.25 or 12.5% of exotic genes. This trend was true for root lodging, stalk lodging and ear diseases but not for plant and ear height. The midparent heterosis for yield varied from -16.1 to 40.3%. Midparent heterosis with positive and negative values were also found for the other traits. The results indicate the potential of exotic germplasm for developing good hybrids. After choosing the best exotic source, some recurrent selection might be appropriate in order to adapt and improve the exotic populations.
Heterochromatin differentiation in holocentric chromosomes of Rhynchospora (Cyperaceae)
Authors: Vanzela André L.L. , Guerra Marcelo
Published: April 2005

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.
Karyotype morphology and evolution in some Lathyrus (Fabaceae) species of southern Brazil
Authors: Klamt Adriane , Schifino-Wittmann Maria Teresa
Published: April 2005

The karyotypes of Lathyrus nervosus Lam., L. pubescens Hook. et Arn., L. paranensis Burk. and L. crassipes Gill ap. Hook et Arn., native to Rio Grande do Sul (southern Brazil), are described in detail for the first time. All taxa have 2n = 14 chromosomes. The karyotypic formulae were 2 m + 12 sm for L. nervosus, L. pubescens and L. paranensis and 4 m + 10 sm for L. crassipes. In all species, the smallest chromosome pair bore a secondary constriction with a satellite in the long arm. Intraspecific variability in the position and number of secondary constrictions was observed in L. nervosus and L. pubescens. All of the species had a conservative and similar karyotype morphology, but differed in total complement size by as much as 20% between the highest (L. nervosus) and lowest (L. crassipes) values. These results suggest that changes in chromosome size during evolution have been similar for all the chromosomes of the complement. Together with data on the life cycle and mode of reproduction, these results also indicate that L. crassipes is a derived taxon, if an evolutionary trend towards a decrease in chromosome size is accepted.
Development of pollen grain in yellow passion-fruit (Passiflora edulis f. flavicarpa; Passifloraceae)
Authors: Souza Margarete Magalhães de , Pereira Telma Nair Santana
Published: April 2005

To clarify events occurring during pollen grain formation in yellow passion-fruit (Passiflora edulis f. flavicarpa), floral buds were collected at different stages of development. After bracket, petal and sepal removal the anthers were fixed, dehydrated, embedded in paraffin wax, sectioned at 10 mum and after differential dying with safranin O and fast green, mounted in Canada balsam and observed under optical microscope. Formation of the male gamete followed the normal pattern for angiosperms. Observation covered final sporogenic mass phase up to pollen grain formation; microsporangium tissue modifications were also observed. Microsporogenesis was characterized by sporogenic tissue differentiation in microsporic mother cells, followed by meiosis and resulting in tetrads. Microgametogenesis began with callose microspore release, subsequent mitosis, in addition to radial and tangential tapetum wall degradation, parietal layer compression nearer to the tapetum and endothecium widening, terminating in mature pollen grain formation.
Mode of reproduction of Brazilian species of Adesmia (Leguminosae)
Authors: Tedesco Solange B. , Dall'Agnol Miguel , Schifino-Wittmann Maria Teresa , Valls José F.M.
Published: April 2005

Mode of reproduction was studied in 15 species of Adesmia DC. (Leguminosae). In six species, three treatments were used: mutual pollination, mechanical stimulation and control. Fifty-four plants of these six species were grown in a greenhouse, individually isolated in nylon screen boxes. Flowers were labelled and submitted to the different treatments. In addition, the frequency of spontaneous self-pollination in the absence of pollinators was studied in 200 plants of nine other species. These 200 plants were kept in a greenhouse, which avoided contact with any possible pollinator. Adesmia bicolor, A. muricata, A. punctata and A. riograndensis produced seed both by cross- and self-pollination. Adesmia punctata and A. riograndensis need mechanical stimulation for self-pollination. Adesmia incana reproduced by self-pollination; however, the possibility of cross-pollination cannot be totally ruled out. Adesmia tristis reproduced mainly by cross-pollination and a mechanism of self-incompatibility is suggested. Among the nine species that were not exposed to pollinators, A. securigerifolia produced a large amount of seed, indicating that it is a self-pollinating species. Adesmia arillata, A. araujoi, A. ciliata, A. psoraleoides, A. rocinhensis, A. reitziana, A. sulina and A. vallsii did not produce any seed under the experimental conditions, suggesting that they are cross-pollinated or that they need mechanical stimulation to reproduce.
Micronucleus frequencies in Astyanax bimaculatus (Characidae) treated with cyclophosphamide or vinblastine sulfate
Authors: Matsumoto F.E. , Cólus I.M.S.
Published: April 2005

Two known mutagenic drugs, cyclophosphamide and vinblastine sulfate, were tested using the micronucleus test in the native fish species, Astyanax bimaculatus, in order to determine which of these drugs and the doses which would be the most adequate for use as positive controls in this species. This Brazilian fish species was chosen because few toxicity studies have used native fish species and this particular species is widely consumed in various regions of Brazil. Three thousand erythrocytes per specimen were scored. Doses of 16 and 8 mg/kg body weight of cyclophosphamide and vinblastine sulfate, respectively, were the most effective in causing micronuclei. Cyclophosphamide was the most mutagenic of the two drugs and is recommended for use as a positive control in A. bimaculatus.
A simple method for the detection of recombinogenic substances in filamentous fungi
Authors: Baracho Marta dos Santos , Baracho Ivanhoé Rodrigues
Published: April 2005

Several tests are available for detecting mutagenic and recombinogenic products in fungi. Since fungi are eukaryotic, these tests permit the detection of substances that produce chromosomal aberrations, or that are recombinogenic. We have developed a new method for testing substances that affect fungal stability using a duplication strain of Aspergillus nidulans and circular statistics for data analysis. The fungus was inoculated on the center of Petri dishes and the substance to be tested was applied to a defined area of the dish. Position of resulting sectors was measured by an angle and the data were analyzed by the Rayleigh test. Extensive testing with different compounds showed this method to be rapid and efficient for screening recombinogenic substances.
Demography, genetic diversity, and population relationships among Argentinean Mapuche Indians
Authors: Goicoechea Alicia S. , Carnese Francisco R. , Caratini Alicia L. , Avena Sergio , Salaberry Maria , Salzano Francisco M.
Published: April 2005

Fertility, mortality and migration data from four Mapuche Indian communities located along a 215-km NE-SW linear area in the Province of Río Negro, Argentina, were collated with genetic information furnished by nine blood group systems and by mtDNA haplogroups. The demographic and genetic data indicated a clear dichotomy, which split the four populations into two groups of two. Differing degrees of non-Indian exchanges was probably the main determining factor for this separation. Total genetic variability was very similar in all groups, and the interpopulational variability accounted for only 10% of the total variability. A low prevalence of the Diego(a) antigen among the Mapuche was confirmed. The fact that significant genetic heterogeneity and population clusters were found in such a small territorial region attests to the sensitivity of demographic and genetic approaches in unraveling human history.
Establishment of an adherent cell layer from human umbilical cord blood
Authors: Alfonso Zeni Z.C. , Forneck Eduardo D. , Allebrandt Waldir F. , Nardi Nance B.
Published: April 2005

In addition to bone marrow and peripheral blood, stem cells also occur in human umbilical cord blood (HUCB), and there is an increasing interest in the use of this material as an alternative source for bone marrow transplantation and gene therapy. In vitro hematopoiesis has been maintained for up to 16 weeks in HUCB cultures, but the establishment of an adherent, stromal layer has consistently failed. Adherent cell precursors among mononuclear cells from HUCB were sought for in long-term cultures. Mononuclear cells obtained from cord blood after full term, normal deliveries were cultivated at different concentrations in Iscove's modified Dulbecco's medium (IMDM) with weekly feeding. An adherent layer was detected in 16 of 30 cultures, 12 of which were plated at cell concentrations higher than 2 x 10(6) cells/ml. In contrast to bone marrow cultures, in which the stroma is detected early, in most (10/16) positive cultures from HUCB the adherent layer was identified only after the fourth week of culture. The cells never reached confluence and detached from the plate approximately four weeks after detection. May-Grünwald-Giemsa staining of positive cultures revealed fibroblast- or endothelial-like adherent cells in an arrangement different from that of bone marrow stroma in 13 samples. In two of these, the adherent cells were organized into characteristic, delimited cords of cells. Unlike bone marrow cultures, fat cells were never observed in the adherent layers. A rapid development of large myeloid cells in the first week of culture was characteristic of negative cultures and these cells were maintained for up to 12 weeks. HUCB contains adherent cell precursors which occur in lower numbers than in bone marrow and may be at a different (possibly less mature) stage of differentiation.
Frequency of the CCRdelta32 allele in Brazilians: a study in colorectal cancer and in HTLV-I infection
Authors: Pereira Rinaldo W. , Pires Edina R. , Duarte Ana P.M. , Moura Ricardo P. de , Monteiro Elisangela , Torloni Humberto , Proietti Anna B. , Simpson Andrew J.G. , Pena Sérgio D.J.
Published: April 2005

The identification of a 32-bp deletion in the cc-chemokine receptor-5 gene (CCR5delta32 allele) that renders homozygous individuals highly resistant to HIV infection has prompted worldwide investigations of the frequency of the CCR5delta32 allele in regional populations. It is important to ascertain if CCR5delta32 is a factor to be considered in the overall epidemiology of HIV in individual populations. With this in mind we determined the CCR5delta32 allele frequency in a large sample (907 individuals) of the southeastern Brazilian urban population, stratified as follows: 322 healthy unrelated individuals, 354 unselected colorectal cancer patients, and 229 blood donors. The three groups displayed essentially identical allelic frequencies of CCR5delta32 and pairwise comparisons did not show significant differences. Thus, our results can be pooled to provide a reliable estimate of the CCR5delta32 allele frequency in the southeastern Brazil of 0.053 ± 0.005. The blood donors comprised 50 HTLV-I serologically negative individuals, 115 non-symptomatic individuals HTLV-I positive by ELISA but with indeterminate Western blot results, 49 healthy blood donors HTLV-I positive both at ELISA and Western blot and 15 patients with clinical spinal cord disease (HAM). A suggestive trend was observed, with the CCR5delta32 frequencies decreasing progressively in these four categories. However, when we applied Fischer's exact test no significant differences emerged. We believe that further studies in larger cohorts should be performed to ascertain whether the CCR5delta32 allele influences the chance of becoming infected or developing clinical symptoms of HTLV-I infection.
Syntenic homology of human unique DNA sequences within chromossome regions 5q31, 10q22, 13q32-33 and 19q13.1 in the great apes
Authors: Vallente-Samonte Rhea U. , Conte Robert A. , Verma Ram S.
Published: April 2005

Homologies between chromosome banding patterns and DNA sequences in the great apes and humans suggest an apparent common origin for these two lineages. The availability of DNA probes for specific regions of human chromosomes (5q31, 10q22, 13q32-33 and 19q13.1) led us to cross-hybridize these to chimpanzee (Pan troglodytes, PTR), gorilla (Gorilla gorilla, GGO) and orangutan (Pongo pygmaeus, PPY) chromosomes in a search for equivalent regions in the great apes. Positive hybridization signals to the chromosome 5q31-specific DNA probe were observed at HSA 5q31, PTR 4q31, GGO 4q31 and PPY 4q31, while fluorescent signals using the chromosome 10q22-specific DNA probe were noted at HSA 10q22, PTR 8q22, GGO 8q22 and PPY 7q22. The chromosome arms showing hybridization signals to the Quint-EssentialTM 13-specific DNA probe were identified as HSA 13q32-33, PTR 14q32-33, GGO 14q32-33 and PPY 14q32-33, while those presenting hybridization signals to the chromosome 19q13.1-specific DNA probe were identified as HSA 19q13.1, PTR 20q13, GGO 20q13 and PPY 20q13. All four probes presumably hybridized to homologous chromosomal locations in the apes, which suggests a homology of certain unique DNA sequences among hominoid species.
FISH studies in a girl with sporadic aniridia and an apparently balanced de novo t(11;13)(p13;q33) translocation detect a microdeletion involving the WAGR region
Authors: Llerena Jr. J.C. , Cabral de Almeida J.C. , Bastos E. , Crolla J.A.
Published: April 2005

Conventional cytogenetic studies on a female infant with sporadic aniridia revealed what appeared to be a balanced de novo t(11;13) (p13;q33) translocation. Fluorescence in situ hybridization (FISH) investigations, however, detected the presence of a cryptic 11p13p14 deletion which included the WAGR region and involved approximately 7.5 Mb of DNA, including the PAX6 and WT1 genes. These results account for the patient's aniridia, and place her at high risk for developing Wilms' tumour. The absence of mental retardation in the patient suggests that the position of the distal breakpoint may also help to refine the mental retardation locus in the WAGR contiguous gene syndrome (Wilms', aniridia, genital anomalies and mental retardation).
Spatial pattern and genetic diversity estimates are linked in stochastic models of population differentiation
Authors: Diniz-Filho José Alexandre Felizola , Telles Mariana Pires de Campos
Published: April 2005

In the present study, we used both simulations and real data set analyses to show that, under stochastic processes of population differentiation, the concepts of spatial heterogeneity and spatial pattern overlap. In these processes, the proportion of variation among and within a population (measured by G ST and 1 - G ST, respectively) is correlated with the slope and intercept of a Mantel's test relating genetic and geographic distances. Beyond the conceptual interest, the inspection of the relationship between population heterogeneity and spatial pattern can be used to test departures from stochasticity in the study of population differentiation.
Localization of genes modulating the predisposition to schizophrenia: a revision
Authors: Lopes-Machado E.Z. , Duarte F.A.M.
Published: April 2005

The genetics of schizophrenia or bipolar affective disorder has advanced greatly at the molecular level since the introduction of probes for the localization of specific genes. Research on gene candidates for susceptibility to schizophrenia can broadly be divided into two types, i.e., linkage studies, where a gene is found near a specific DNA marker on a specific chromosome, and association studies, when a condition is associated with a specific allele of a specific gene. This review covers a decade of publications in this area, from the 1988 works of Bassett et al. and Sherrington et al. on a gene localized on the long arm of chromosome 5 at the 5q11-13 loci, to the 1997 work of Lin et al. pointing to the 13q14.1-q32 loci of chromosome 13 and to the 1998 work of Wright et al. on an HLA DRB1 gene locus on chromosome 6 at 6p21-3. The most replicated loci were those in the long arm of chromosome 22 (22q12-q13.1) and on the short arm of chromosome 6 (6p24-22). In this critical review of the molecular genetic studies involved in the localization of genes which modulate the predisposition to schizophrenia the high variability in the results obtained by different workers suggests that multiple loci are involved in the predisposition to this illness.
Karyotype, constitutive heterochromatin and nucleolar organizer regions (NORs) in Belosacris coccineipes (Acrididae-Leptysminae)
Authors: Loreto Vilma , Souza Maria José de
Published: April 2005

Several techniques including C-banding, fluorochromes and silver staining were used to obtain information about heterochromatin patterns in the grasshopper B. coccineipes. Conventional staining showed a karyotype with 2n = 23 chromosomes in males and 2n = 24 in females, as well as XO:XX sex determination and acrotelocentric chromosomes. The medium-sized X chromosome was heteropycnotic positive at the beginning of prophase I and negative in metaphase I. C-banding revealed heterochromatic blocks in the pericentromeric regions of all chromosomes. Silver nitrate staining in this species showed three small bivalents (S9-S11) as nucleolar organizers with NORs located in the pericentromeric regions. CMA3-positive blocks were seen in pericentromeric regions of pairs M6, S9, S10 and S11. Sequential staining with CMA3/AgNO3 revealed homology between the CMA3-positive bands and NORs of the bivalents S9, S10 and S11. The CMA3-positive block of the bivalent M6 could represent a latent secondary NOR. The results obtained permit us to distinguish two categories of the constitutive heterochromatin in B. coccineipes.
A multivariate approach to the association pattern of reciprocal translocations induced by chemicals and ionizing radiation in mouse germ cells
Authors: De Luca J.C. , Ortiz Jaureguizar E. , Dulout F.N.
Published: April 2005

The degree of similarity between chemical and physical agents in their capacity to induce reciprocal translocations was analyzed by means of multivariate analysis techniques. The effect of three different doses of gamma rays, four doses of X-rays and different doses of adriamycin, mitomycin C, thio-tepa and bleomycin was analyzed. Data were arranged in a basic matrix by two methods: cluster analysis and ordination. Two main groups were found, one including doses of 9 and 10 Gy and the other including the remaining lower doses of ionizing radiation and the other chemicals. Various subgroups were found within the second group. Accordingly, using presence/absence data there was not a specific pattern of chromosomal damage induction for physical and chemical agents. The increase in the frequencies of reciprocal translocation observed with 9 and 10 Gy was due to an increase in the kind of multivalent configurations. This variability could be dose dependent. Likewise, the similarity observed in the second group between the chemicals and the lower doses of ionizing radiation could also be dose dependent.
Chromosome comparison between two species of Phyllostomus (Chiroptera - Phyllostomidae) from Eastern Amazonia, with some phylogenetic insights
Authors: Rodrigues Luís R.R. , Barros Regina M.S. , Assis Maria de Fátima L. , Marques-Aguiar Suely A. , Pieczarka Julio C. , Nagamachi Cleusa Y.
Published: April 2005

The karyotypes of Phyllostomus discolor and P. hastatus from Eastern Amazonia were studied by G-, C-, G/C sequential and Ag-NOR techniques. Both species presented 2n = 32, with the autosome complement composed of 30 bi-armed in P. discolor and 28 bi-armed plus 1 acrocentric in P. hastatus. In both species, the X chromosome is medium submetacentric while the Y is minute acrocentric. The present study found only one difference between the karyotypes of P. discolor and P. hastatus: the smallest autosome (pair 15) is bi-armed in discolor and acrocentric in hastatus, a result best explained by pericentric inversion. The C-banding revealed constitutive heterochromatin only at the centromeric regions of all chromosomes, with the NOR site located at the distal region of short arm of pair 15, in both species. The taxon P. discolor is considered primitive for genus Phyllostomus and the bi-armed form of pair 15 is the assumed primitive condition which, rearranged by a pericentric inversion originated the acrocentric from found in P. hastatus.
DNA extraction from sea anemone (Cnidaria: Actiniaria) tissues for molecular analyses
Authors: Pinto S.M. , Fernandes-Matioli F.M.C. , Schlenz E.
Published: April 2005

A specific DNA extraction method for sea anemones is described in which extraction of total DNA from eight species of sea anemones and one species of corallimorpharian was achieved by changing the standard extraction protocols. DNA extraction from sea anemone tissue is made more difficult both by the tissue consistency and the presence of symbiotic zooxanthellae. The technique described here is an efficient way to avoid problems of DNA contamination and obtain large amounts of purified and integral DNA which can be used in different kinds of molecular analyses.