Célia Maria Torres Cordeiro

Variability in micronucleus induction with different mutagens applied to several species of fish

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.

Selection of Beauveria bassiana and Metarhizium anisopliae isolates to control Triatoma infestans

Twenty three isolates of Beauveria bassiana and 13 isolates of Metarhizium anisopliae were tested on third instar nymphs of Triatoma infestans, a serious vector of Chagas disease. Pathogenicity tests at saturated humidity showed that this insect is very susceptible to fungal infection. At lower relative humidity (50%), conditions expected in the vector microhabitat, virulence was significantly different among isolates. Cumulative mortality 15 days after treatment varied from 17.5 to 97.5%, and estimates of 50% survival time varied from 6 to 11 days. Maintaining lower relative humidity, four B. bassiana and two M. anisopliae isolates were selected for analysis of virulence at different conidial concentrations and temperatures. Lethal concentrations sufficient to kill 50% of insects (LC50) varied from 7.1 x 10(5) to 4.3 x 10(6) conidia/ml, for a B. bassiana isolate (CG 14) and a M. anisopliae isolate (CG 491) respectively. Most isolates, particularly B. bassiana isolates CG 24 and CG 306, proved to be more virulent at 25 and 30 degrees C, compared to 15 and 20 degrees C. The differential virulence at 50% humidity observed among some B. bassiana isolates was not correlated to phenetic groups in cluster analysis of RAPD markers. In fact, the B. bassiana isolates analyzed presented a high homogeneity (> 73% similarity).

Analysis of genetic susceptibility to mercury contamination evaluated through molecular biomarkers in at-risk Amazon Amerindian populations

We investigated Individual differences in susceptibility to methylmercury (MeHg) contamination and its relationship with polymorphisms of the detoxifying enzyme glutathione S-transferase (GST). In Brazil, some Amerindian tribes from the Amazon region have an increased level of mercury in their hair. Samples of hair and blood were taken from inhabitants of two villages in the Kayabi and Munduruku Amerindian communities to investigate mercury levels in association with genetic polymorphism of GSTs. Other molecular biological markers were also studied, such as hemoglobin, haptoglobin and glucose 6-phosphate dehydrogenase (G-6-PDH). Higher levels of mercury contamination were found in the Kayabi villagers, who had a null genotype (GSTM1 0/0, also denominated GSTM1 null) frequency of 26%, than in the Munduruku villagers, for which the null genotype frequency was 0%. Individuals with the GSTM1 null phenotype had higher concentrations of mercury in their hair than individuals with GSTM1+/+ phenotypes (F = 21.51, p < 0.0001). No association with other markers studied was observed. This study suggests that GSTM1 may be involved in the biotransformation of mercury in humans.

Associação do polimorfismo do gene do hormônio de crescimento com a caraterística peso em bovinos da raça Nelore

The polymorphism of the growth hormone gene (bGH) was studied in 211 Nellore pure breed bovine males to estimate the genotype and allelic frequencies and possible associations of the gene with weight traits. For this study, body weight data were collected at birth, weaning and monthly from 10 to 16 months of age. Additionally, weight gains from birth to weaning and weaning to 16 months of age were calculated. DNA was extracted from blood samples and the animals genotyped for Msp I (bGH/Msp I, 891 bp), Hae III (bGH/Hae III, 441 bp) and Alu I (bGH/Alu I, 427 bp) polymorphic sites. Every polymorphism presented two alleles. The predominant alleles were D, F and A, respectively. The effect of the bGH/Alu I AA genotype was observed on the weight gain from weaning to 15 months of age, and of the bGH/Msp I DD genotype from weaning to 14 and 15 months. The results suggest that bGH/Alu I and bGH/Msp I polymorphisms may be potential markers for the weight gain trait in young bulls.

Control of Triatoma infestans (Klug) (Reduviidae: Triatominae) with Beauveria bassiana (Bals.) Vuill.: preliminary assays on formulation and application in the field

O fungo Beauveria bassiana (Bals.) Vuill., isolado CG 306, foi testado contra o Triatoma infestans (Klug) atraves de aplicacao indireta por contato do inseto com papel filtro tratado com conidios. O patogeno foi aplicado sobre papel filtro atraves de filtragem a vacuo de uma suspensao de conidios. Foram feitas estimativas do tempo medio de sobrevivencia entre 15 e 21 dias nas densidades de 3x106 e 107 conidios/cm2, respectivamente, sem diferencas significativas entre as concentracoes. A concentracao de 2,4x106 conidios/cm2 de CG 306 foi necessaria para matar 50% de ninfas de terceiro instar de T. infestans 25 dias apos inoculacao e incubacao a 25°C e 50% de umidade relativa. A CL50 foi estatisticamente maior (2,0x107 conidios/cm2) quando os insetos foram expostos por uma hora aos conidios distribuidos sobre papel filtro. Um emulsificante a base de oleo mineral (2%) nao afetou a germinacao de conidios in vitro. Um numero menor de conidios foi necessario para matar 50% dos insetos apos exposicao constante ao papel filtro tratado, em comparacao com os conidios nao formulados com o emulsificante. Quando a exposicao foi limitada a 1 h, os conidios nao formulados foram mais efetivos do que conidios formulados. Apos aplicacao de B. bassiana (107 conidios/cm2) em pequenas casas experimentais de madeira, seguida de liberacao de ninfas de terceiro instar de T. infestans, o nivel de infeccao de insetos recuperados 25 dias apos aplicacao com o fungo foi significativamente inferior as encontrado na casa-testemunha. A mortalidade atribuida a infeccao fungica de insetos recuperados e mantidos em laboratorio foi de 38,1 a 93,8%. A mortalidade de insetos expostos ao papel filtro tratado e mantido em copos cobertos com gaze dentro das casas, foi de 35 a 78,8% 25 dias apos aplicacao. A persistencia dos conidios foi superior a 98% durante os experimentos de campo. Nao houve desenvolvimento de B. bassiana sobre cadaveres originados de infeccao provocada em laboratorio e posteriormente expostos as condicoes de campo no interior das casas.

Viral reinfection affecting bulb production in garlic after seven years of cultivation under field conditions

Six sequential field experiments were conducted from 1999 to 2002 to evaluate virus reinfection in garlic cv. Amarante and its effect on bulb production. The treatments in the year 1999 were: T1 – virus-free garlic-seed obtained by thermotherapy and meristem-tip culture and indexed for virus by immuno-sorbent electron microscopy (ISEM) under its first field cycle; T2, T3 and T4 – garlic-seed in the second, third and fourth field cycles, respectively; and C – standard garlic-seed from the grower (with no control of virus infection) as a control. In the years 2000 to 2002, a new plot of virus-free seed was added to the experiment and cloves from the previous treatments were again grown under field conditions. In the fourth year of experiments, the treatments comprised T1 (virus-free garlic seeds under the first field cycle) to T7 (garlic-seed in the sixth field cycle) and C. Two experiments were conducted in the years 1999 and 2000, at two locations and in the years 2001 and 2002 only one experiment per year at one location. The combined analysis of variance for all experiments indicated a significant difference between the treatments for plant height and yield. The bulbs were classified into commercial classes according the Brazilian regulation and the commercial classes 4–7 were 72 %, 60%, 59%, 53% and 35% of the total number of bulbs harvested, from T1 to T5, respectively. Virus reinfection at the end of the second field cycle, determined by serology using antisera against the most common viruses of garlic in Brazil reached 83%. Treatments T1–T7 yielded 118%, 79%, 57%, 51%, 39%, 33% and 31% higher than the control.

Relação da Circunferência Escrotal e Parâmetros da Qualidade do Sêmen em Touros da Raça Nelore, PO

In 960 Nellore purebred bulls, of 11.4 to 135 months of age, belonging to farms located in the Sao Paulo, Goias and Para states, was studied the possible association among the size of the scrotal circumference (CE) and sperm quality parameters, progressive motility (MOT) and sperm pathologies: the major (DEFMAI), minor (DEFMIN) and total (DEFTOT) defects. The bulls were divided by age in groups: minor than 18, from 18 to 24, from 24 to 30, from 30 to 36 and major than 36 months of age. This study was accomplished with the purpose of obtaining sizes of CE that may indicate the functional status of the testicles through the quality of the semen that can be used to predict the reproductive potential of the animals destined to the selection of bulls. Of the correlation of CE with MOT, by age group, resulted an association (R = 0,60; P<0.0001) of these parameters in the bulls up to 18 months of age, which CE above 26 cm indicated semen of high MOT (60 to 80%). The correlation between CE and sperm pathologies was very low and negatives. It was concluded that in the young bulls the size of CE indicates the quality of the semen, therefore it can be used as a criteria for the selection of animals of high reproductive potential.

Molecular characterization of Brazilian Dicyma pulvinata isolates

Quarenta e nove isolados brasileiros de Dicyma pulvinata foram analisados quanto a caracteristicas morfologicas, analises de RFLP, RAPD e AFLP. Este fungo e um micoparasita do Microcyclus ulei, o agente causal da mais importante doenca da seringueira (Hevea brasiliensis), o mal-das-folhas. Estes isolados foram comparados com isolados indianos obtidos a partir de lesoes de Cercosporidium sp., com um isolado proveniente da Franca obtido a partir de lesoes de Cladosporium fulvum e com um isolado de D. ampullifera proveniente de Papua-Nova Guine. A analise de parâmetros morfologicos confirmou a identificacao dos isolados brasileiros. As representacoes graficas das matrizes de distância de cada marcador molecular mostraram resultados semelhantes. Os isolados de D. pulvinata obtidos de M. ulei mostraram-se intimamente relacionados. Por outro lado, os isolados - referencia, incluidos nestes estudos, mostraram-se bastante dispersos. De acordo com a analise de variância molecular, considerando todos os marcadores, os isolados de D. pulvinata obtidos de M. ulei, apresentaram diferenca significativa entre isolados procedentes de areas de cultivo de seringueira favoraveis a ocorrencia do mal-das-folhas (regioes norte e nordeste do Brasil) e aqueles de areas de escape da doenca (Mato Grosso).

Possible Associations between Bovine Growth Hormone Gene Polymorphism and Reproductive Traits

The polymorphism of the bovine growth hormone gene (bGH) was studied in 211 Nellore pure breed males for association with reproductive traits. Scrotal circumference and testosterone concentrations were collected monthly from 10 until 16 months of age. Additionally, testicular growth rates were calculated. DNA was amplified by PCR and digested using Msp I and Hae III restriction enzymes. Every polymorphism presented two alleles. The predominant alleles were D (0.85) and F (0.98), respectively, and genotype EE - bGH/Hae III was missing. Significant association (P<0.05) between bGH/Msp I polymorphism, scrotal circumference and testicular growth after puberty, as well as between bGH/Hae III and testosterone concentrations at puberty were detected. The results suggested that these association could be useful for selection, since bGH/Msp I and bGH/Hae III polymorphisms could be considered as markers for testicular development after puberty and onset of puberty, respectively.

Polymorphism of the grasshopper Rhammatocerus schistocercoides populations revealed by RAPD

(2) Abstract - The objective of this work was to study the genetic variabil- ity of the grasshopper Rhammatocerus schistocercoides (Orthoptera: Acrididae) using RAPD analysis among individuals from three popula- tions, one from Colombia and two from Brazil (Goias and Mato Grosso States). Ninety scorable binary markers were obtained by fingerprinting with 11 oligonucleotide primers. Most of the polymorphism was attrib- uted to 42 markers with variable frequency among the different popula- tions. Although the existence of significant difference among popula- tions (P<0.0001), most of the genetic variability was found within popu- lations (87.7% of total variation). Pairwise distances between Colom- bian and Brazilian populations were 0.12 (P<0.0001) and 0.18 (P<0.0001) for Goias and Mato Grosso, respectively. The pairwise distance be- tween Goias and Mato Grosso populations was 0.06 (P<0.0001). These data indicated that the phenotypic differences among populations are associated mainly with the geographical distances between the Brazilian and Colombian populations.