Resumo em Inglês:

The glutathione S-transferase mu (GSTM1) gene which acts during phase II of xenobiotic metabolism is polymorphic in the population, being absent in about 30-50% of individuals depending on the ethnic group from which they come. Epidemiological studies suggest that individuals who are homozygous null at the GSTM1 locus may have an increased risk of developing various types of neoplastic disease. We used the polymerase chain reaction (PCR) to estimate the frequency of GSTM1 in 176 healthy individuals from the north of Paraná (Brazilian state), the null genotype being detected in 48.86% of these individuals. The Student’s t-test was used to evaluate the frequency of the glutathione S-transferase null genotype in relation to age, gender and smoking habit and no significant differences were found. In our sample there were 142 individuals of Caucasian origin, of which 47.88% had the null genotype. When applied to the Caucasian group only (n = 142) the Student’s t-test again showed no significant differences between the frequency of the GSTM1 null genotype and age, gender and smoking habit.

Resumo em Inglês:

Estrogen plays a role in the pathogenesis of leiomyoma. The CYP17 gene codes for the cytochrome P450c17alpha enzyme, which is involved in the biosynthesis of estrogen. Our aim was to investigate if CYP17 polymorphism could be a useful marker to predict the susceptibility to leiomyoma. Our sample of female subjects was divided into two groups: (1) with leiomyoma (n = 159); (2) without leiomyoma (n = 128). A 169-bp fragment encompassing the A1/A2 polymorphic site of the CYP17 gene was amplified by polymerase chain reaction (PCR), restricted by enzyme MspA1I and electrophored on agarose gel. Genotypes and allelic frequencies for this polymorphism in both groups were compared. There was no significant difference between the two groups regarding the distribution of the CYP17 gene polymorphism frequencies. The A1 homozygote/heterozygote/A2 homozygote proportions for CYP17 in both groups were: (1) 17.0/46.5/36.5%, and (2) 17.2/45.3/37.5%. The proportions for alleles A1 and A2 were also comparable in the two groups. A1 and A2 allele frequencies were: 7% (40.3/59) in group 1, and 2% (39.8/60) in group 2. No significant association was observed between the risk of leiomyoma and polymorphisms of the CYP 17 gene. So, CYP17 gene polymorphism does not appear to be a useful marker for the prediction of leiomyoma susceptibility.

Resumo em Inglês:

The purpose of this work was to verify the ability of the enzyme Alu I to cleave and/or remove satellite DNA sequences from heterochromatic regions in chromosomes of bats, by identifying the occurrence of modifications in the pattern of fluorescence in situ hybridization with telomeric DNA. The localization and fluorescence intensity of the telomeric DNA sites of the Alu-digested and undigested chromosomes of species Eumops glaucinus, Carollia perspicillata, and Platyrrhinus lineatus were analyzed. Telomeric sequences were detected at the termini of chromosomes of all three species, although, in C. perspicillata, the signals were very faint or absent in most chromosomes. This finding was interpreted as being due to a reduced number of copies of the telomeric repeat, resulting from extensive telomeric association and/or rearrangements undergone by the chromosomes of Carollia. Fluorescent signals were also observed in centromeric and pericentromeric regions in several two-arm chromosomes of E. glaucinus and C. perspicillata. In E. glaucinus and P. lineatus, some interstitial and terminal telomeric sites were observed to be in association with regions of constitutive heterochromatin and ribosomal DNA (NORs). After digestion, these telomeric sites showed a significant decrease in signal intensity, indicating that enzyme Alu I cleaves and/or removes part of the satellite DNA present in these regions. These results suggest that the telomeric sequence is a component of the heterochromatin, and that the C-band- positive regions of bat chromosomes have a different DNA composition.

Resumo em Inglês:

Cytogenetic studies were done on three Pomacentridae species of the genus Chromis. The karyotype of C. multilineata consisted of 48 acrocentric chromosomes (FN = 48), C. insolata had 2n = 46-47 (3-4M+6SM+36-38A; FN = 56) and C. flavicauda had 2n = 39 (9M+6SM+24A; FN = 54). Robertsonian polymorphisms were detected in C. insolata and C. flavicauda. All three species had small heterochromatic blocks restricted to centromeric regions. Nucleolar organizer regions (NORs) were detected in the telomeric position of a medium acrocentric chromosome pair in C. multilineata and in non-homologous chromosomes in both C. flavicauda and C. insolata. FISH with a telomeric probe detected no internal telomeric sequences in C. flavicauda and C. insolata. 5S rRNA genes were observed in a pericentromeric region of two large metacentric chromosome pairs in C. flavicauda and two large acrocentric pairs in C. insolata. The karyotype structure and the number and location of the 5S rDNA loci in these two species indicated that the 5S rRNA-bearing acrocentric chromosomes were directly involved in the origin of the polymorphisms observed. These data reinforce the idea that Robertsonian rearrangements have been involved in molding the karyotype in the subfamily Chrominae.

Resumo em Inglês:

In the Rio Doce basin of southeastern Brazil, the freshwater fish Hoplias malabaricus (trahira) is a widespread predatory characin and one of the few resilient native fishes in a highly impacted lake system. In order to test for genetic differentiation in populations within this basin and for biogeographic relationships among populations of this species in other basins, a study was conducted using RAPD-PCR analysis of Rio Doce samples (N = 63) and phylogeographic analyses with mitochondrial DNA (mtDNA) haplotypes, including the Rio Grande and Macacu river basins. In the Rio Doce basin, the patterns of genetic similarity of RAPD-PCR markers (individual fingerprinting and Nei’s genetic distance) suggest the existence of two genetically different groups, one composed of the lacustrine populations Carioca and Dom Helvécio, and the other of riverine and the remaining lacustrine populations. The differences in the RAPD-PCR patterns may be explained by the existence of sub-basins within this lacustrine system. A maximum parsimony tree of cytochrome b fragment (383 base pairs) supports the view that trahiras of the Rio Doce share a complex biogeographic history with those of neighboring basins. The phylogeographic patterns may be explained by a common history of the watersheds of the Rio Doce, Paraíba do Sul, and Rio Grande basins, corroborating the hypothesis of a Plio-Pleistocene separation of these drainage systems, forming the Mantiqueira "divortium aquarium".

Resumo em Inglês:

A correct relationship among sires is essential for an efficient breeding program. Microsatellite markers were used in progeny tests, to assess the paternity of seventy-four probable offspring of nine Gir dairy sires. A 36% misidentification rate was observed; however, these errors had minimal effects on the ranking of the nine bulls with regard to their genetic values. The results suggest that paternity tests should be performed in breeding programs, in order to prevent inappropriate paternities from influencing the genetic value of bulls in the future.

Resumo em Inglês:

The O5 chromosomal inversion has been a cornerstone for understanding different aspects of the American colonization by Drosophila subobscura. To obtain more information of this evolutionary event it is important to know the pattern of bands of this inversion in detail. Comparing this pattern with that of D. melanogaster it is possible to predict which genes are located inside or close to the O5 inversion and use them as genetic markers. In this study, the complete band pattern of the O5 inversion is presented. Furthermore, the most important genes located inside it have been predicted. Finally, a constriction located close to the proximal breakage point of the O5 inversion has been observed many times and its possible genetic significance is discussed.

Resumo em Inglês:

Restriction fragment length polymorphism (RFLP) analysis of mitochondrial DNA (mtDNA) was employed to characterize species and populations of Astyanax, a Neotropical freshwater fish genus. Samples of five species, A. altiparanae, A. fasciatus, A. lacustris, A. scabripinnis paranae and A. schubarti, from the Upper Paraná and São Francisco river basins were analyzed. Two out of the ten restriction enzymes employed generated species-specific mtDNA patterns for each of the five species. MtDNA exhibited considerable polymorphism within and among populations. All populations sampled showed relatively high values of haplotype diversity. Geographically localized haplotypes were detected for A. altiparanae and A. fasciatus from the Upper Paraná and São Francisco basins. The relationships between populations are discussed.

Resumo em Inglês:

In salmonid species, nucleolar organizing regions (NORs) have frequently been found on a single chromosome pair. However, some other, smaller yet active NORs have also been described. In the present study, NORs were found to be located in different positions on the chromosomes of 12 rainbow trout samples (11 cultivated and one naturalized stocks). Three phenotypes were found: 1) NORs located on two submetacentric chromosomes, in a subterminal position on the short arm (AA); 2) NORs located on two submetacentric chromosomes, in a subterminal position on the long arm (BB); and 3) NORs located on two submetacentric chromosomes, one in a subterminal position on the short arm, and the other in a subterminal position on the long arm (AB). Phenotype AA was identified in individuals from ten cultivated stocks, phenotype AB was identified in individuals from three cultivated stocks, and phenotype BB was found in one cultivated and one wild stock. Some aspects of the origin and the distribution of the different phenotypes are discussed.

Resumo em Inglês:

Data from five protein-coding loci related to dairy production were used to study the genetic diversity and population structure of Argentine and Bolivian Creole cattle breeds. Genomic DNA was extracted from blood samples of six Creole cattle breeds: Argentine (n = 230), Patagonian (n = 25); "Saavedreño" (n = 140), "Chaqueño Boliviano" (n = 30), "Yacumeño" (n = 27), and "Chusco" (n = 11). kappa-casein, beta-lactoglobulin, growth hormone and prolactin were measured by PCR-RFLP, while alphaS1-casein was typed by PCR-ASO. The results are discussed, focusing on: historical origin, recent differentiation and selection events, Zebu gene introgression, and population structure. This work shows that: (i) For the studied genes, the observed gene frequency profiles of Argentine and Bolivian Creole cattle breeds were close to the data reported for Iberian breeds and for other South-American Creole cattle breeds which are historically related; (ii) although Zebu gene introgression has been reported at the studied loci, these breeds seem to be far from the Zebu gene frequency profiles; and (iii) the Argentine and Bolivian Creole cattle showed significant levels of subdivision, but each population has maintained its degree of genetic variability.

Resumo em Inglês:

Astyanax fishes are among the most important food-web components of South America rivers. In the Iguaçu River basin, the Astyanax genus is represented mainly by endemic species. For millions of years, that hydrographic basin has been geographically isolated from the Paraná River basin by the Iguaçu Falls. Recently, a species from the Upper Paraná River basin identified as Astyanax bimaculatus was revised and described as a new species named Astyanax altiparanae Garutti & Britski, 2000. Fauna endemism and geographic isolation triggered interest in investigations to evaluate the identification and genetic relatedness among two A. altiparanae populations from the Upper Paraná River basin and the population identified as A. bimaculatus in the Iguaçu River, upstream from the Iguaçu Falls. Mitochondrial DNA sequences and RAPD markers revealed high genetic diversity within each population, as well as low genetic distance, high gene flow, and high mitochondrial DNA similarity among all three populations. In conjunction with morphological similarities, these results demonstrated that the population presently known as Astyanax bimaculatus in the Iguaçu River should actually be stated as Astyanax altiparanae. Furthermore, it could be inferred that the A. altiparanae population is not endemic and most likely it was recently introduced in the Iguaçu River basin, maintaining the ancestral genetic identity.

Resumo em Inglês:

The genetic variation in two farmed strains (F3-Panama and F17-Venezuela) of the shrimp Litopenaeus vannamei was examined based on DNA multiloci analyses. Eighteen adults of each strain were analyzed by PCR using a set of VNTR core sequence primers. Genetic similarity, mean allele frequency, mean heterozygosity and the frequency of polymorphic loci were determined for both strains. A dendrogram of genetic similarity was produced by UPGMA clustering. The results for three primers (INS, M13, YN73) revealed different levels of genetic variation within the strains. The higher genetic similarity seen within strain F17 was apparently related to inbreeding, although a bottleneck effect could not be discarded. The low level of genetic variability of this strain could account for the reduced adaptive advantage of these animals and their inability to adjust to breeding conditions in Brazil.

Resumo em Inglês:

Clustering and ordination procedures in multivariate analyses have been widely used to describe patterns of genetic distances. However, in some cases, such as when dealing with Jaccard coefficients based on RAPD data, these techniques may fail to represent genetic distances because of the high dimensionality of the genetic distances caused by stochastic variation in DNA fragments among the units analyzed (species or populations). In this note, we show how Mantel tests can be used to test hypotheses about genetic distances and avoid problems with multivariate data representation. The procedure is illustrated with RAPD data comparing 20 anuran species from the cerrado, in which Jaccard genetic distances were compared to three model matrices linking the species at distinct taxonomic levels.

Resumo em Inglês:

The study of inbreeding depression is important for breeding strategies such as use of inbred progenies or extraction of inbreed lines. A diallel of 28 maize open-pollinated varieties was evaluated in 10 environments in the early 1990s. At the same time, S1 populations for each of the 28 varieties were evaluated in the same 10 experiments (environments). Yield reductions of the populations from S0 to S1 (mean of the 10 environments), varied from 34.6% (CMS-01) to 59.2% (CMS-30), with an average of 49.1%. Inbreeding depression was greater in populations with a wider genetic base, which had never been exposed to inbreeding (CMS-30, BR-107, PH4, Cunha, Saracura, Nitrodent, and Nitroflint). Inbred lines with greater yield means should be obtained from the BR-105, BR-111, CMS-01, CMS-03, BR-106, CMS-14c, and CMS-28 populations. The use of parameter estimates generated by analysis of inbreeding depression, allow to make inferences about frequencies of deleterious alleles in the population. The frequencies of favorable alleles in the parents can be obtained by diallel analysis. The association of these two types of information, can provide a better interpretation of the genetic parameters and also can improve the process of selection of parents for either an intra- or an inter-populational breeding program.

Resumo em Inglês:

The objectives of this study were to estimate changes in oil content, grain yield, percentage of broken plants and changes in yield components in the maize populations DS7u and YuSSSu. As estimations were performed at C0 and C9 for both populations, it was possible to observe changes occurring following long-term mass selection for high oil content. The synthetic population DS7u population was developed by recombination of 29 inbred lines of Yugoslav, Canadian and US origin. The synthetic population YuSSSu population is an Iowa Stiff Stalk Synthetic - BSS(R)C5. Progenies were derived according to the North Carolina Design II. Results indicated that nine cycles of selection led to statistically significant increase in oil content and statistically significant decrease for grain yield in both populations. Estimates of additive and dominance variances for grain oil content were highly significant in C0 and C9 of the population DS7u population. Dominance variance showed significance in the initial cycle of the population YuSSSu population, but it was not detected in the course of nine cycles of mass selection. Additive and dominance variances for grain yield were highly significant in both initial populations. Loss of significance did not result from selection, while the proportion of dominance vs. additive variance became greater. High narrow-sense heritability was detected for grain yield, oil content, moisture content, and cob percent in the initial cycles of both populations. Mass selection resulted in increased heritability for oil content and cob percent in the DS7u population and increased heritability for percentage of broken plants in the YuSSSu population. The strongest additive correlation between oil content and other traits was detected for grain moisture (r a = 0.90*) in the C9 of the DS7u population.

Resumo em Inglês:

The long juvenile period (LJP) characteristic of soybean (Glycine max L. Merrill) cultivars delays flowering under short-day conditions. This trait may be important in increasing the adaptation range of soybean to low latitudes and provides greater flexibility for sowing times within the same latitude. The inheritance of the long juvenile period was studied in the MG/BR22 (Garimpo) soybean cultivar to provide knowledge to support the development of cultivars adapted to short day conditions. Four cultivars (‘Paraná’, ‘Bossier’, ‘Bragg’, and ‘Davis’) were crossed among each other and with MG/BR 22 (‘Garimpo’). The study was conducted under short-day conditions (early sowing) in a greenhouse and in the field, in Londrina, Paraná, (23°22’ south latitude). The parents and the F1, F2, and F3 populations were assessed daily for flowering. The genotype ratios of 15:1 (p > 0.95, chi² test) and 8:7:1 (p = 0.193) for the F2 and F3 generations, respectively, obtained for the Paraná x Bossier cross indicated a case of digenic interaction with a duplicate recessive epistatic effect for the LJP character. Segregation of the F2 population from the MG/BR 22 (Garimpo) x Paraná cross resulted in the expected ratio of 3:1 (p = 0.166, indicating that the MG/BR 22 (Garimpo) and Paraná cultivars differed at a single locus. Similarly, in the MG/BR 22 (Garimpo) x Bossier cross, a 3:1 (p = 0.065) segregation indicated that these two cultivars differed at a single locus for number of days to flowering. The Davis cultivar had the same gene for LJP as the Paraná cultivar (aa). The F2 segregation of the classic flowering Bragg with MG/BR 22 (Garimpo) cross resulted in a 15:1 (p = 0.138) ratio, indicating that these two cultivars differed at two loci for flowering. The genotypes assigned to the cultivars were aaBB for Paraná, AAbb for Bossier and aabb for MG/BR 22 (Garimpo). A single locus in recessive homozygosis does not produce LJP.

Resumo em Inglês:

The yellow passion fruit, Passiflora edulis f. flavicarpa, is one of the most important Brazilian fruit crops. It is an allogamous, diploid, and self-incompatible species. It has hermaphrodite, solitary flowers, located in the leaf axils and protected by leaf bracts. The flower has an androgynophore, which is a straight stalk supporting its reproductive parts. There are usually five anthers, located at the tip of each of the five filaments. The ovary is borne just above the filaments, at the top of the androgynophore; there are three styles that are united at their base, and at the top there are three stigmas. The objective of this research was to observe embryo sac development in yellow passion flowers. Ovaries at different stages of development were fixed in FAA (formalin, acetic acid and alcohol solution), hydrated, stained with Mayer’s hemalum, and dehydrated. Ovules were cleared by using methyl salicylate, mounted on slides, and observed through a confocal scanning laser microscope. The yellow passion fruit ovule is bitegmic, crassinucellate, and anatropous, and its gametophyte development is of the Polygonum type. After meiosis, functional megaspores under go three successive mitotic divisions, resulting in an eight-nucleate megagametophyte: the egg apparatus at the micropylar end, two polar nuclei at the cell center, and three antipodals at the chalazal end. The egg apparatus is formed by an egg cell and two synergids, each with a filiform apparatus. The mature embryo sac has an egg cell, two synergids, two polar nuclei, and three antipodes, as has been described for most angiosperms.

Resumo em Inglês:

Inter- and intraspecific variation among 26 isolates of ectomycorrhizal fungi belonging to 8 genera and 19 species were evaluated by analysis of the internal transcribed sequence (ITS) of the rDNA region using restriction fragment length polymorphism (RFLP). The ITS region was first amplified by polymerase chain reaction (PCR) with specific primers and then cleaved with different restriction enzymes. Amplification products, which ranged between 560 and 750 base pairs (bp), were obtained for all the isolates analyzed. The degree of polymorphism observed did not allow proper identification of most of the isolates. Cleavage of amplified fragments with the restriction enzymes Alu I, Hae III, Hinf I, and Hpa II revealed extensive polymorphism. All eight genera and most species presented specific restriction patterns. Species not identifiable by a specific pattern belonged to two genera: Rhizopogon (R. nigrescens, R. reaii, R. roseolus, R. rubescens and Rhizopogon sp.), and Laccaria (L. bicolor and L. amethystea). Our data confirm the potential of ITS region PCR-RFLP for the molecular characterization of ectomycorrhizal fungi and their identification and monitoring in artificial inoculation programs.

Resumo em Inglês:

Certain species of fungi of the genus Aspergillus produce a type of cells around the cleistothecium that are called hülle cells. To facilitate the analysis of the formation of these cells, an Aspergillus nidulans strain with high hülle cell production was obtained. Hülle cells from this strain were allowed to grow on dialysis membranes, where it was possible to observe their nuclei. The material was fixed with Carnoy, hydrolyzed with HCl and stained with Giemsa. Several nuclei approximately equal in size to the nuclei of hyphae and conidia were observed during the phase of hülle cell formation. The formation of a macronucleus measuring approximately 3.1 mum was observed in mature hülle cells. To compare the DNA amount, hülle cells and conidia of the CH-89 strain were isolated and submitted to DNA extraction (Tuyl, 1977). The amount of DNA per cell was, on average, 17.2 times greater than the amount of DNA in the conidia.

Resumo em Inglês:

The pectinolytic system of Penicillium griseoroseum has been studied as a model to investigate aspects of gene organization in filamentous fungi. Here we show that the endopolygalacturonase-coding genes previously isolated exist as single copies in the fungus genome. DNA blot analysis revealed the presence of corresponding genes in other Penicillium species, although only one or two genes were found in opposition to the endoPG gene family reported for other filamentous fungi. The nucleotide and amino acid sequences of Penicillium PG genes of retrieved from data banks were compared for intron length and number, codon usage, and consensus sequences for translation initiation sites. The introns are conserved in the same position, although there was no conservation of their nucleotide sequences. Other sequence features resemble those seen in Aspergillus and Neurospora genes.

Resumo em Inglês:

In this study, the micronuclei test (MNT) was applied in exfoliated cells of buccal mucosa, in order to evaluate the genotoxic risk associated with occupational exposure of mechanics, storage battery renovation workers, and car painters. For each individual, 3000 exfoliated buccal cells were analyzed. There was a significantly higher frequency of micronucleated cells (MNC) in the exposed workers than in controls. Smoking and drinking habits, age, and working time did not represent significant factors in terms of increasing the production of micronuclei (MN), when the control and the exposed groups were compared. These results allowed to conclude that the studied individuals belong to a risk group and should periodically undergo biological monitoring and proper care.