Resumo em Inglês:

We applied a combination of comparative genomic hybridization (CGH) and fluorescence in situ hybridization (FISH), to characterize the genetic aberrations in three osteosarcomas (OS) and one Ewing's sarcoma. CGH identified recurrent chromosomal losses at 10p14-pter and gains at 8q22.3-24.1 in OS. Interphase FISH allowed to confirm 8q gain in two cases. A high amplification level of 11q12-qter was detected in one OS. The Ewing's sarcoma showed gain at 1p32-36.1 as the sole chromosome alteration. These studies demonstrate the value of molecular cytogenetic methods in the characterization of recurrent genomic alterations in bone tumor tissue.

Resumo em Inglês:

Spinocerebellar ataxia type 1 (SCA1) and Machado-Joseph disease (MJD/SCA3) are autosomal dominant neurodegenerative diseases caused by expansions of a CAG trinucleotide repeat in the SCA1 and MJD genes. These expanded sequences are unstable upon transmission, leading to an intergeneration increase in the number of repeats (dynamic mutation). The transmission of the CAG repeat was studied in normal mother-father-child trios, referred for paternity testing (SCA1, n = 367; MJD, n = 879). No segregation distortion was detected. The CAG allele frequencies were determined in 330 unrelated individuals (fathers from couples tested for paternity). The allele frequency distributions did not differ from those previously reported for European populations. The estimated values for the statistic parameters indicating diversity at the SCA1 locus did not differ much from those reported previously for other STRs in the Brazilian population, while those for the MJD locus were close to or higher than the maximum values of previous reports. This shows that SCA1 and MJD are highly informative loci for applications in genetic and population studies and for forensic analysis.

Resumo em Inglês:

Head and neck carcinomas represent the sixth most frequent type of cancer in the world, and 90% are derived from squamous cells (HNSCC). In this study of 15 HNSCC cases, extensive aneuploidy was detected by G banding in most tumors. The most frequently observed numerical changes involved gain of a chromosome 22, and loss of chromosomes Y, 10, 17, and 19. The most frequent structural alteration was del(22)(q13.1). As compared to G-banding, fluorescence in situ hybridization (FISH) proved to be an effective technique for detecting aneuploidy. Interphase FISH with a chromosome 17 centromere probe disclosed a high frequency of monosomy for chromosome 17, in contrast with G-banding, by which clonal monosomy 17 was detected in only three of the tumors. Painting probes for chromosomes 5 and 16 were used to evaluate a selected series of HNSCC in which G-banding analysis had shown marker chromosomes. FISH analysis failed to confirm the origin of the marker chromosomes, but four out of five cases showed a significant loss of chromosomes 5. This difference between FISH and G-banding results may reflect the smaller number of metaphase analyzed as well as the criteria adopted for sorting these metaphases. Therefore results obtained solely by G-banding analysis should be considered with caution. Our data confirmed the involvement of chromosome 17 in head and neck squamous cell carcinomas.

Resumo em Inglês:

We report on a 22-year-old male patient and his father, both presenting with congenital sensorineural deafness, diffuse palmoplantar keratoderma and knuckle pads. These findings are similar to those previously described in the Bart-Pumphrey syndrome, a rare autosomal dominant disorder. Several conditions including keratoderma and deafness are briefly reviewed.

Resumo em Inglês:

Aberdeen Angus beef cattle from the Brazilian herd were studied genetically using restriction fragment length polymorphism (RFLP) of the kappa-casein - HinfI (CSN3 - HinfI), beta-lactoglobulin - HaeIII (LGB - HaeIII) and growth hormone AluI (GH- AluI) genes, as well as four microsatellites (TEXAN15, CSFM50, BM1224 and BM7160). The RFLP genotypes were determined using the polymerase chain reaction (PCR) followed by digestion with restriction endonucleases and electrophoresis in agarose gels. With the exception of the microsatellite BM7160, which was analyzed in an automatic sequencer, the PCR products were genotyped by silver staining. The allele and genotype frequencies, heterozygosities and gene diversity were estimated. The values for these parameters of variability were comparable to other cattle breeds. The genetic relationship of the Aberdeen Angus to other breeds (Caracu, Canchim, Charolais, Guzerath, Gyr, Nelore, Santa Gertrudis and Simmental) was investigated using Nei's genetic distance. Cluster analysis placed the Aberdeen Angus in an isolated group in the Bos taurus breeds branch. This fact is in agreement with the geographic origin of this breed.

Resumo em Inglês:

Physical maps of the ribosomal RNA gene 28S of species belonging to the genera Paratelmatobius and Scythrophrys were constructed, using five restriction endonucleases. The restriction sites for Bam HI, Bgl II, Bst EII, and Eco RI had similar positions in all species, although there were interspecific differences in the size of the restriction fragments obtained. An additional Pvu II site was found in Scythrophrys specimens from Piraquara (State of Paraná, Brazil) and from São Bento do Sul (State of Santa Catarina, Brazil), but not in the Scythrophrys specimens from Rancho Queimado (State of Santa Catarina, Brazil). This finding is in agreement with the hypothesis regarding the existence of two species in the genus Scythrophrys. On the other hand, the extra Bst EII site considered in the literature to be a synapomorphy for the subfamilies Leptodactylinae and Telmatobiinae was not observed in the genera Paratelmatobius and Scythrophrys, which brings new questions about some taxonomic classifications that include Paratelmatobius in Leptodactylinae and Scythrophrys in Telmatobiinae. Interspecific variation was observed in the size of the restriction fragments analyzed and, in the case of group I Scythrophrys, there was also a variation between the individuals of the two populations. These data suggest that sequencing of the rDNA segments studied here may be useful in phylogenetic studies of the genera Paratelmatobius and Scythrophrys.

Resumo em Inglês:

A cytogenetic analysis of thirteen specimens of Bryconamericus aff. Iheringii revealed a diploid number of 52 chromosomes and a karyotype of 8M+22SM+10ST+12A with a fundamental number (FN) of 92. The nucleolus organizer regions (NORs) were studied by means of AgNO3 and CMA3 staining as well as by FISH using an 18S rDNA probe. NORs were found to be located at the terminal position on the short arm of the submetacentric chromosome pair. C-banding showed strong telomeric and centromeric staining in the majority of the chromosomes, and a similar pattern was observed after treatment with AluI restriction enzyme

Resumo em Inglês:

The king weakfish (pescada-gó in Portuguese - Macrodon ancylodon (Sciaenidae), a demersal (bottom-feeding) species found in South America Atlantic coastal waters from the Gulf of Paria in Venezuela to Baia Blanca in Argentina, is an economically important species because of its abundance and wide acceptance by consumers. Because of its wide distribution this fish may be subject to geographic isolation and this may have resulted in distinct populations along its coastal range. Considering that this species represents an important economic resource, confirmation of whether M. ancylodon is a single species or there are different genetic stocks spread over its wide distribution would be an important contribution to conservation policies and population management of the king weakfish. To investigate differences between king weakfish populations we used the cytochrome b and 16S rRNA genes to characterize M. ancylodon specimens caught throughout its South American range from Venezuela to Argentina. Our results clearly distinguished two genetically different groups which show nucleotide divergence and genetic structuring patterns that strongly suggest they may be different species, disagreeing with the widely accepted traditional taxonomy that accepts only one species of Macrodon in the western Atlantic.

Resumo em Inglês:

Chromosomal polymorphism in natural populations of Drosophila willistoni from Uruguay and southern Brazil was investigated in order to understand the genetic characteristics and evolutionary potential of these almost geographically marginal populations. The level of chromosomal polymorphism in samples from Uruguay was higher than in those from the southernmost Brazilian state of Rio Grande do Sul. The increase in the polymorphism of these populations, in which the species almost reaches its southern limit, contradicts the low level of paracentric inversion polymorphism expected under the central-marginal chromosomal polymorphism cline previously reported. The high frequency of some inversions and the presence of unique inversions in samples from Uruguay indicate the uniqueness of these populations.

Resumo em Inglês:

The aim of this report was to detect full-sized P element sequences in eight strains of Drosophila sturtevanti populations from distant geographic regions and to assess the structural geographic variation among P element sequences. PCR analysis confirmed the presence of a putative complete P element in all strains. Southern blot analysis indicated bands shared by all strains, and bands restricted to geographically related strains. Parsimony analysis corroborated the hybridization pattern that reflected the geographic relationships.

Resumo em Inglês:

Eighteen enzymatic loci were analysed in Aedes aegypti populations from four neighbourhoods in the city of Manaus. The analyses showed that the Downtown population was the most polymorphic (p = 55.6%) with higher observed and expected mean heterozygosities (Ho = 0.152 ± 0.052; He = 0.174 ± 0.052, respectively). The least variability was detected in the Coroado and Cidade Nova populations, both with polymorphism of 44.4%. The latter population presented the least observed heterozygosity (Ho = 0.109 ± 0.037). Wright's F statistics showed that the mean value of Fis was higher than that of Fst (Fis = 0.164 > Fst = 0.048), and from analysis of molecular variance (AMOVA) it was found that 95.12% of the variability is found within populations indicating a certain intra-population differentiation possibly of the microgeographic structure resulting from some barrier in the random coupling. Although the four populations were similar genetically (D = 0.003 to 0.016), the 4.88% differentiation was significant.

Resumo em Inglês:

The study of variability generated by phenotypic plasticity is crucial for predicting evolutionary patterns in insect-plant systems. Given sufficient variation for plasticity, host race formation can be favored and maintained, even simpatrically. The plasticity of size and performance (assessed by the lifetime fitness index r m) of six clones of Myzus persicae was tested, with replicates allowed to develop on two hosts, kale (Brassica oleracea var. acephala) and radish (Raphanus sativus). The clones showed significant variability in their plasticity. Reaction norms varied through generations and negative genetic correlation, although not significant, tend to increase with the duration of host use. The lack of plasticity in lifetime fitness among generalist clones occurred as an after-effect of the highly plastic determinants. Significant morphological plasticity in host used was observed, but no variation in the plastic responses (GxE interaction) was detected. Strong selection for a larger size occurred among individuals reared on radish, the most unfavorable host. Morphological plasticity in general body size (in a multivariate sense) was not linear related to fitness plasticity. These observations suggest that a high potential for the evolution of host divergence favors host race formation.

Resumo em Inglês:

Polyacrylamide gel electrophoresis system (PAGE) and inhibition tests for biochemical characterization of alpha- and beta-esterases were used to obtain a functional classification of esterases fromAspidosperma polyneuron. The characterization of alpha- and beta-esterases from young leaves of A. polyneuron by the PAGE system showed fourteen esterase isozymes. The differential staining pattern showed that Est-2 isozyme hydrolyzes beta-naphthyl acetate; Est-6, Est-7 and Est-8 isozymes hydrolyze alpha-naphthyl acetate, and Est-1, Est-3, Est-4, Est-5, Est-9, Est-10, Est-11, Est-12, Est-13, and Est-14 isozymes hydrolyze both alpha- and b-naphthyl acetate. Inhibition pattern of a- and beta-esterases showed that Folidol is a more potent inhibitor that Malathion, while Thiamethoxan (an insecticide with organophosphorus-like action) acts as an Est-4 and Est-6 inhibitor and induces the appearance of Est-5 and Est-7 isozymes as more intensely stained bands. Inhibition tests showed that OPC insecticides inhibit or activate plant esterases. Thus, plant esterases may be used as bioindicators to detect the presence and toxicity of residues of topically applied insecticides in agriculture and may be valuable for monitoring pollutants in the environment.

Resumo em Inglês:

Rhynchospora tenuis Link (Cyperaceae) is a weed widely distributed in Brazil that presents a small number of holocentric chromosomes (2n = 4) with some autopolyploid populations (2n = 8). The haploid number n = 2 is considered as a derivative of the base number x = 5. 45S rDNA probes and telomeric DNA were hybridized in both chromosome races of R. tenuis, looking for indications of chromosome fusions. The results showed that hybridization sites of the telomeric probe were restricted to end chromosome regions whereas rDNA sites were terminally located. The chromosome race with n = 4 exhibited a doubled number of sites, with similar size and location to the hybridized sequences, confirming its autopolyploid origin. Furthermore, the terminal location of the single 45S rDNA site in the 2n = 4 race suggested that disploid reduction in Rhynchospora, from n = 5 to n = 2, was followed by elimination or reorganization events, keeping the terminal distribution of these sites, as in an others species of the genus.

Resumo em Inglês:

The objective of this work was to assess the functionality of the glycolytic pathways in the bacterium Xylella fastidiosa. To this effect, the enzymes phosphoglucose isomerase, aldolase, glyceraldehyde-3-phosphate dehydrogenase and pyruvate kinase of the glycolytic pathway, and glucose 6-phosphate dehydrogenase of the Entner-Doudoroff pathway were studied, followed by cloning and expression studies of the enolase gene and determination of its activity. These studies showed that X. fastidiosa does not use the glycolytic pathway to metabolize carbohydrates, which explains the increased duplication time of this phytopatogen. Recombinant enolase was expressed as inclusion bodies and solubilized with urea (most efficient extractor), Triton X-100, and TCA. Enolase extracted from X. fastidiosa and from chicken muscle and liver is irreversibly inactivated by urea. The purification of enolase was partial and resulted in a low yield. No enzymatic activity was detected for either recombinant and native enolases, aldolase, and glyceraldehyde-3-phosphate dehydrogenase, suggesting that X. fastidiosa uses the Entner-Doudoroff pathway to produce pyruvate. Evidence is presented supporting the idea that the regulation of genes and the presence of isoforms with regulation patterns might make it difficult to understand the metabolism of carbohydrates in X. fastidiosa.

Resumo em Inglês:

The Escherichia coli RecA protein (RecAp) has been demonstrated to induce mutagenesis in yeast cells, although there is still little information on the role of the RecAp in yeast recombination events. We evaluated spontaneous and induced general recombination in vegetative and meiotic cells of the XS2316 strain of the yeast Saccharomyces cerevisiae bearing the recA gene. We found that RecAp decreased reciprocal recombination, gene conversion and intrachromosomal recombination and promoted an increase in error-prone processes in both vegetative and meiotic cells, while its negative effect on meiotic recombination blocked ascospore formation.

Resumo em Inglês:

Environmental and genetic factors affecting the in vitro spontaneous mutation frequencies to aminoglycoside resistance in Escherichia coli K12 were investigated. Spontaneous mutation frequencies to kanamycin resistance were at least 100 fold higher on modified Luria agar (L2) plates, when compared to results obtained in experiments carried out with Nutrient agar (NA) plates. In contrast to rifampincin, the increased mutability to kanamycin resistance could not be attributed to a mutator phenotype expressed by DNA repair defective strains. Kanamycin mutant selection windows and mutant preventive concentrations on L2 plates were at least fourfold higher than on NA plates, further demonstrating the role of growth medium composition on the mutability to aminoglycosides. Mutability to kanamycin resistance was increased following addition of sorbitol, suggesting that osmolarity is involved on the spontaneous mutability of E. coli K12 strains to aminoglycosides. The spontaneous mutation rates to kanamycin resistance on both L2 and NA plates were strictly associated with the selective antibiotic concentrations. Moreover, mutants selected at different antibiotic concentrations expressed heterogeneous resistance levels to kanamycin and most of them expressing multiple resistance to all tested aminoglycoside antibiotics (gentamicin, neomycin, amykacin and tobramycin). These results will contribute to a better understanding of the complex nature of aminoglycoside resistance and the emergence of spontaneous resistant mutants among E. coli K12 strains.