Validation of EST-derived microsatellite markers for two Cerrado-endemic Campomanesia (Myrtaceae) species.

We assessed the transferability of 120 EST-derived Eucalyptus microsatellite primers to Campomanesia adamantium and C. pubescens. Both species are berry trees native to the Brazilian Cerrado, and population genetic information is poor. Twelve markers were used to analyze the genetic variability of four sampled populations. Regarding DNA extraction, we sampled leaf tissues from two populations of each species (80 individuals). Of the 120 primers evaluated, 87 did not amplify any PCR products, and 21 rendered nonspecific amplification. Twelve primers were successfully transferred, providing a low combined probability of genetic identity for both species (5.718 x 10(-10) for C. adamantium; 1.182 x 10(-11) for C. pubescens) and a high probability of paternity exclusion (0.99939 for C. adamantium; 0.99982 for C. pubescens). The average number of alleles in the polymorphic loci was 6.8 for C. adamantium and 7.8 for C. pubescens, ranging from 2 to 16 alleles per locus. The observed heterozygosity values for C. adamantium and C. pubescens were 0.504 and 0.503, respectively, and the expected heterozygosity values for C. adamantium and C. pubescens were 0.517 and 0.579, respectively. The populations exhibited structured genetic variability with qP values of 0.105 for C. adamantium and 0.249 for C. pubescens. Thus, we concluded that these 12 microsatellite markers, transferred from Eucalyptus, were efficient for population genetic studies of C. adamantium and C. pubescens.

Geographical genetics of Pseudoplatystoma punctifer (Castelnau, 1855) (Siluriformes, Pimelodidae) in the Amazon Basin.

Geographical genetics allows the evaluation of evolutionary processes underlying genetic variation within and among local populations and forms the basis for establishing more effective strategies for biodiversity conservation at the population level. In this study, we used explicit spatial analyses to investigate molecular genetic variation (estimated using 7 microsatellite markers) of Pseudoplatystoma punctifer, by using samples obtained from 15 localities along the Madeira River and Solimões, Amazon Basin. A high genetic diversity was observed associated with a relatively low FST (0.057; P < 0.001), but pairwise FST values ranged from zero up to 0.21 when some pairs of populations were compared. These FST values have a relatively low correlation with geographic distances (r = 0.343; P = 0.074 by Mantel test), but a Mantel correlogram revealed that close populations (up to 80 km) tended to be more similar than expected by chance (r = 0.360; P = 0.015). The correlogram also showed a exponential-like decrease of genetic similarity with distance, with a patch-size of around 200 km, compatible with isolation-by-distance and analogous processes related to local constraints of dispersal and spatially structured levels of gene flow. The pattern revealed herein has important implications for establishing strategies to maintain genetic diversity in the species, especially considering the threats due to human impacts caused by building large dams in this river system.

First Report of Colletotrichum boninense Causing Anthracnose on Pepper in Brazil.

Colletotrichum boninense was isolated from pepper (Capsicum annuum) fruits (cv. Amanda) with preharvest anthracnose symptoms collected in the Brazilian states of Rio Grande do Sul and São Paulo in July of 2005. In the field, the disease affected mature fruits and leaves with an incidence near 25%. Typical symptoms in fruits were circular, sunken lesions with orange spore masses in a dark center. Three single conidia isolates were obtained from infected fruits. When grown on potato dextrose agar at 25°C with a 12-h photoperiod, these isolates produced white colonies with a cream-to-orange color in the opposite side, but no sclerotia. Conidia were cylindrical, had obtuse ends and a hilum-like low protuberance at the base, and measured 13.5 to 15.5 × 4.6 to 5.1 µm. Conidial length/width ratio was 2.8 to 3.0. These morphological characteristics are consistent with the description of C. boninense (1). To confirm pathogen identity, the internal transcribed spacer rRNA region was sequenced (GenBank Accession Nos. FJ010199, FJ010200, and FJ010201) and compared with the same region of C. boninense (GenBank Accession No. DQ286160.1). Similarity between these sequences was 98 to 99%. The pathogenicity of the three isolates was determined on pepper fruits cv. Amanda. Attached as well as detached fruits from potted plants were inoculated. Inoculation was performed by depositing 40-µl droplets of a suspension (105 conidia per ml) on the surfaces of nonwounded (detached n = 5; attached n = 5) and wounded (detached n = 5; attached n = 5) fruits with a sterilized hypodermic needle. Incubation took place in a moist chamber for 12 days at 25°C with a 12-h photoperiod. Inoculation of control fruits was similar in procedure and number to that of test fruits, except sterile distilled water was used instead of the conidial suspension. Symptoms, observed in wounded and nonwounded test fruits 3 to 5 days after inoculation, were characterized by necrotic, sunken zones containing acervuli, black setae, and orange spore masses. Control fruits presented no symptoms. Pathogens reisolated from infected fruits showed the same morphological and molecular characteristics of the isolates previously inoculated. To our knowledge, this is the first report of C. boninense infecting pepper in Brazil. Reference: (1) J. Moriwaki et al. Mycoscience 44:47, 2003.

Identifying relevant molecular descriptors related to carcinogenic activity of polycyclic aromatic hydrocarbons (PAHs) using pattern recognition methods.

Polycyclic Aromatic Hydrocarbons (PAHs) constitute an important family of molecules capable of inducing chemical carcinogenesis. In this work we report structure-activity relationship (SAR) studies for 81 PAHs using the pattern-recognition methods Principal Component Analysis (PCA), Hierarchical Clustering Analysis (HCA) and Neural Networks (NN). The used molecular descriptors were obtained from the semiempirical Parametric Method 3 (PM3) calculations. We have developed a new procedure that is capable of identifying the PAHs' carcinogenic activity with an accuracy higher than 80%. PCA selected molecular descriptors that can be directly correlated with some models proposed to PAHs' metabolic activation mechanism leading to the formation of PAHs-DNA adducts. PCA, HCA and NN validate the energy separation between the highest occupied molecular orbital and its next lower level as a major descriptor defining the carcinogenic activity. This descriptor has been only recently discussed in the literature as one new possible universal parameter for defining the biological activity of several classes of compounds.

Structure--activity relationship studies of substituted 17alpha-acetoxyprogesterone hormones.

Recently a new methodology, called electronic indices methodology (EIM), based on local density of state calculations (LDOS) using topological and semiempirical methods, was proposed to identify the biological activity of polycyclic aromatic hydrocarbons (PAHs). In this work we apply the concepts of the EIM approach to classify the progestational activity of 21 17alpha-acetoxyprogesterones (steroid hormones) (APs). The EIM approach pointed to a few descriptors, which correctly classify the active/inactive compounds of this class (approximately 90%). We show that these descriptors arise naturally from principal component analysis (PCA) and neural network (NN) calculations. Moreover, using only the parameters from EIM, instead of a large set of descriptors that have been used before to describe the biological activity of these hormones, we slightly improve and simplify PCA and NN results. Finally, the molecular region related to the chemical activity of these hormones naturally appears in our theoretical analysis, from the local density of states of the frontier orbitals. This shows the generality of the principles of EIM approach, and confirms that the combination of these distinct methodologies can be an efficient and powerful tool in the structure-activity studies of many different classes of compounds.

Structure-activity relationship studies of carcinogenic activity of polycyclic aromatic hydrocarbons using calculated molecular descriptors with principal component analysis and neural network methods.

Recently a new methodology based on local density of state (LDOS) calculations using topological and semiempirical methods was proposed to identify the carcinogenic activity of polycyclic aromatic hydrocarbons (PAHs). In this work we perform a comparative study of this methodology with principal component analysis (PCA) and neural networks (NN). The PCA and NN results show that LDOS quantum chemical descriptors are relevant descriptors to identify the carcinogenic activity of methylated and non-methylated PAHs. Also, we show that the combination of these distinct methodologies can be an efficient and powerful tool in the structure-activity studies of PAHs compounds. We have studied 81 methylated and non-methylated PAHs, and our study shows that with the use of these methods it is possible to correctly predict the carcinogenic activity of PAHs with accuracy higher than 80%.

Mutagenic and genotoxic effects of mate (Ilex paraguariensis) in prokaryotic organisms.

1. The mutagenic and genotoxic effects of mate (Ilex paraguariensis) aqueous solutions were analyzed in bacterial cells. 2. Mate solutions showed mutagenic activity in the Ames test (TA97, TA98, TA100 and TA102 strains) at concentrations of 20 to 50 mg/plate (mutagenic factors of 3.5 to 5.6) and genotoxic activity in the inductest (WP2s (lambda) strain), with a maximal phage induction at concentrations of 10 to 20 mg/plate. Above these concentrations the mate solutions were cytotoxic. 3. Addition of 5 U/ml catalase, 20 microliters/ml S9 rat liver microsomal fraction, 100 mM thiourea or 10 mM dipyridyl completely inhibited the lysogenic induction produced by mate; however, the addition of 1,000 U/ml superoxide dismutase was almost ineffective. 4. Oxygen reactive species may be present in mate solutions playing an essential role in its genotoxicity.

Mutagenic and genotoxic effects of mate (Ilex paraguariensis) in prokaryotic organisms

1. The mutagenic and genotoxic effects of mate (Ilex paraguariensis) aqueous solutions were analyzed in bacterial cells. 2. Mate solutions showed mutagenic activity in the Ames test (TA97, TA98, TA100 and TA102 strains) at concentrations of 20 to 50 mg/plate (mutagenic factors of 3.5 to 5.6) and genotoxic activity in the inductest (WP2s (lambda) strain), with a maximal phage induction at concentrations of 10 to 20 mg/plate. Above these concentrations the mate solutions were cytotoxic. 3. Addition of 5 U/ml catalase, 20 microliters/ml S9 rat liver microsomal fraction, 100 mM thiourea or 10 mM dipyridyl completely inhibited the lysogenic induction produced by mate; however, the addition of 1,000 U/ml superoxide dismutase was almost ineffective. 4. Oxygen reactive species may be present in mate solutions playing an essential role in its genotoxicity.