Judith Viégas

Evaluation of genotoxicity through micronuclei test in workers of car and battery repair garages

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.

C-bands in chromosomes 1,9, and 16 of twins

SummaryThirty-two pairs of Caucasoid twins, 16 monozygotic (MZ) and 16 dizygotic (DZ) of the same sex, were studied in relation to the C-bands of chromosomes 1, 9, and 16. Concordance was not absolute among MZ, the best evaluation of the degree of genetic determination for these traits being 0.40 for chromosome 16, 0.64 for chromosome 1, and 0.73 for chromosome 9. Possible explanations for the failure to obtain 100% concordance are methodologic shortcomings, intercell variations in chromosome contraction, and unequal mitotic crossing over.

VARIABILIDADE GENÉTICA PARA TEOR DE AÇÚCARES REDUTORES EM BATATAS SILVESTRES QUE OCORREM NO SUL DO BRASIL

Reducing sugar and dry matter are very important traits in potatoes for processing. Two wild potato species, Solanum commersonii, subspecies commersonii and malmeanum, and S. chacoense, subspecie mu, occur in the South of Brazil. These species are important for breeding programs, since they have variability for several important traits, such as drought and frost resistance, disease and insect resistance, and dry matter content.. The objectives of this research were to verify the genetic variability for reducing sugar content in wild potato clones of species that occur in this region and to estimate its heritability. Fifty wild potato clones, aleatorily chosen, of Embrapa Clima Temperado collection were grown in screen house, in autumn and spring season of 1996. In autumn, 30 and, in spring, 40 clones produced tubers for the reducing sugar analysis. Tuber sugar content was determined by using the Lane Enyon method and identified by the Somogyi method, modified by NELSON (1944). The results indicated that these species have genetic variability for reducing sugars, with high heritability, mainly in the fall season.

Meiosis of anther culture regenerants in asparagus (Asparagus officinalis L.)

Foi analisada a meiose em celulas mae de polen de plantas de aspargo (Asparagus officinalis L.) de uma populacao composta exclusivamente de plantas masculinas, obtidas atraves do processo de cultura de anteras do hibrido G27 X 22-8. Foi observado que, durante o processo de cultura de anteras, via calogenese, as celulas mae de polen dos regenerantes apresentaram grande instabilidade genomica, evidenciada por irregularidades nas fases de diacinese, assim como de metafase, anafase, telofase da primeira e segunda divisao meiotica. Alem disto, o processo originou anormalidades cromossomicas estruturais em adicao as aneuploidias e poliploidias.

Caracterização cromossômica de Anthurium gaudichaudianum (Araceae), uma espécie nativa do Brasil

The karyotype of Anthurium gaudichaudianum Kunth, a species belonging to the Araceae family, is described for the first time. The species is native to Brazil, occurring from the state of Rio Grande do Sul to the state of Sao Paulo, and the specimens examined were collected from Brazilian Atlantic Forest, in the woods of the municipalities of Torres and Peruibe, located in the states of Rio Grande do Sul, and Sao Paulo, Brazil, respectively. Anthurium gaudichaudianum has 2n = 2x = 30 and its karyotype is formed by three pairs of metacentric chromosomes, nine pairs of submetacentric chromosomes and three pairs of acrocentric chromosomes, one of them with satellites (6 m + 18 sm + 6 a). The size of the chromosomes vary from nearly 6.0 to 2.8 μm. The complement of 30 chromosomes for A. gaudichaudianum found in our study is in accordance with the findings of 2n number for most of species in this large genus.

Genetic variance of reducing sugars and dry matter and their correlations with agronomic traits in potatoes.

The objective of this research was to estimate the components of the variance and heritability relating to reducing sugars content and to dry matter, and their correlations with some agronomic traits of potato (Solanum tuberosum L.). Forty potato clones randomly chosen by the EmbrapaCentro de Pesquisa Agropecuaria de Clima Temperado Breeding Program were used. The field experiments were carried out in the fall and in the spring of 1996, in Pelotas, RS, Brazil. Sugar and dry matter content were analyzed after storing tubers in cold chamber (5±1oC). Genetic variances relating to reducing sugars and to dry matter content were moderate, and error variances were high, providing relatively low heritability values for both traits. The reducing sugar content was positively and significantly correlated with most of the agronomic traits and negatively correlated with dry matter content. The correlations between dry matter and agronomic traits were low and not significant.

Variance of genetic reducing sugars and dry matter and their correlations with agronomic traits in potatoes

The objective of this research was to estimate the components of the variance and heritability relating to reducing sugars content and to dry matter, and their correlations with some agronomic traits of potato (Solanum tuberosum L.). Forty potato clones randomly chosen by the EmbrapaCentro de Pesquisa Agropecuaria de Clima Temperado Breeding Program were used. The field experiments were carried out in the fall and in the spring of 1996, in Pelotas, RS, Brazil. Sugar and dry matter content were analyzed after storing tubers in cold chamber (5±1oC). Genetic variances relating to reducing sugars and to dry matter content were moderate, and error variances were high, providing relatively low heritability values for both traits. The reducing sugar content was positively and significantly correlated with most of the agronomic traits and negatively correlated with dry matter content. The correlations between dry matter and agronomic traits were low and not significant.

Efeitos de meios de cultura na formação de calos a partir de anteras de aspargo (Asparagus officinalis L.)

Anther culture is an auxiliary technique to obtain new genotypes. In this work, anthers with pollen grains in the uninucleated stage of hybrids 56x22-8 and 47x22-8 were cultured in MS medium, semi-solid and liquid, with different concentrations of growth regulators: medium A - 0,5 mg/l BAP + 0,1 mg/l NAA + 0,5 mg/1 2,4-D + 20 g/l sucrose + 20 g/l glucose; medium B - 0,5 mg/1 2,4-D + 30 g/l sucrose; medium C - 3,0 mg/l NAA + 0,5 mg/l Kin + 30 g/l sucrose and medium D - 2,0 mg/l NAA + 0,5 mg/l Kin + 30 g/l sucrose. Callus formation varied with the genotype and the medium. Liquid media showed more efficiency in callus development than the semi-solids. For the hybrids 56x22-8 the best media were the liquid A2 with 80,5% of callus induction and among the semi-solids the D1, with 41,6%. For the hybrid 47x22-8 were liquid D2 with 68,1% and semi solid D1 with 15,2%. No significant differences were observed among the liquid media nor among the semi-solidones.