Ana Cristina Menezes Mendes Gomes

Estirpes de Bacillus thuringiensis efetivas contra insetos das ordens Lepidoptera, Coleoptera e Diptera

The aim of this work was to select among 300 strains of Bacillus thuringiensis those which are simultaneously effective against larvae of Spodoptera frugiperda J.E. Smith and Anticarsia gemmatalis Hubner (Lepidoptera: Noctuidae), Anthonomus grandis Boheman (Coleoptera: Curculionidae), Aedes aegypti Linnaeus and Culex quinquefasciatus Say (Diptera: Culicidae). Two strains of B. thuringiensis were selected, S234 and S997, which presented activity against those three insect orders. Both strains were characterized by morphological, biochemical and molecular methods. They have presented two main proteins with 130 and 65 kDa, polimerase chain reaction products with expected sizes for detection of the genes cry1Aa, cry1Ab, cry1Ac, cry1B and cry2 and bipiramidal, cubical and spherical crystals.

Midgut GPI-anchored proteins with alkaline phosphatase activity from the cotton boll weevil (Anthonomus grandis) are putative receptors for the Cry1B protein of Bacillus thuringiensis

Cry toxins from Bacillus thuringiensis (Bt) are used for insect control. They interact with specific receptors located on the host cell surface and are activated by host proteases following receptor binding resulting in midgut epithelial cells lysis. In this work we had cloned, sequenced and expressed a cry1Ba toxin gene from the B thuringiensis S601 strain which was previously shown to be toxic to Anthonomus grandis, a cotton pest. The Cry1Ba6 protein expressed in an acrystaliferous B. thuringiensis strain was toxic to A. grandis in bioassays. The binding of Cry1Ba6 toxin to proteins located in the midgut brush border membrane of A. grandis was analyzed and we found that Cry1Ba6 binds to two proteins (62 and 65kDa) that showed alkaline phosphatase (ALP) activity. This work is the first report that shows the localization of Cry toxin receptors in the midgut cells of A. grandis.

Recombinant Cry1Ia protein is highly toxic to cotton boll weevil (Anthonomus grandis Boheman) and fall armyworm (Spodoptera frugiperda).

Aims:  To evaluate the activity of cry1Ia gene against cotton pests, Spodoptera frugiperda and Anthonomus grandis.

Diversity of Meloidogyne arenaria using morphological, cytological and molecular approaches

Thirteen Meloidogyne arenaria isolates representing two cytological types (3n = 51-56, 2n = 42-48) and four enzymatic phenotypes (esterase and malate dehydrogenase: A3N1, A2N1, A1N1, A2N3) were studied using different approaches. The analysis of molecular markers showed a high level of polymorphism among the isolates. The trees obtained with RAPD or ISSR polymorphisms showed concordant results and agree with morphological studies. By considering morphometrical and morphological features, it was possible to conclude that the isolate with enzymatic phenotype A2N3 race 1 was the M. arenaria described in 1949 by Chitwood and appearing clearly separated in the trees, as well as in the outgroups. The seven isolates with phenotype A2N1 from different localities and isolate A1N1 can be considered morphometrically typical of M. arenaria race 2 and they were apparently clustered by geographical origin. Morphologically, they differed from isolate A2N3 race 1. The two isolates with phenotype A3N1 appeared to be closely related to the isolate of M. morocciensis and, considering all of the features described for this species, were identified as such. The two isolates A2N3 race 2 were identified either as an atypical M. arenaria or an unidentified species (females and males having atypical stylets), and clustered together and separated from other M. arenaria isolates with high bootstrap support. The same M. arenaria isolates were tested with the species-specific molecular marker, type SCAR. A fragment of 420 bp was obtained for ten isolates of M. arenaria, including the atypical A2N3 race 2 and M. morocciensis. This fragment was not amplified for three typical A2N1 isolates of M. arenaria.

Characterization of novel Brazilian Bacillus thuringiensis strains active against Spodoptera frugiperda and other insect pests

Brazilian strains of Bacillus thuringiensis, namely S701, S764 and S1265 were analysed regarding their cry gene and protein contents, crystal type, and activity against larvae of the lepidopteran fall armyworm (Spodoptera frugiperda Smith), the velvet caterpillar (Anticarsia gemmatalis), the dipterans (Culex quinquefasciatus and Aedes aegypti) and the coleopteran (Tenebrio molitor). The LC50 of the strains against second instar larvae of S. frugiperda or A. gemmatalis revealed a high potency against those insect species. The spore–crystal mixtures of the isolates were analysed by sodium dodecyl sulphate‐polyacrylamide gel electrophoresis (SDS‐PAGE) and showed similar protein pattern as the B. thuringiensis subsp. kurstaki strain HD‐1 (proteins approximately 130 and 65 kDa) for isolates S701 and S764, respectively, and only one major protein of approximately 130 kDa for isolate S1265. The polymerase chain reaction (PCR) using total DNA of the isolates and general and specific primers showed the presence of cry1Aa, cry1Ac, cry1Ia and cry2Ab genes in the two isolates serotyped as B. thuringiensis kurstaki (S701 and S764) and the presence of cry1D and cry2Ad in B. thuringiensis morrisoni S1265 strain. Scanning electron microscopy of strains S701 and S764, showed the presence of bipyramidal, cuboidal and round crystals, like in strain HD‐1 and bipyramidal and round crystals like in strain S1265.

Meloidogyne izalcoensis n. sp. (Nematoda: Meloidogynidae), a root-knot nematode parasitising coffee in El Salvador

A new root-knot nematode parasitising coffee in the region of the Izalco volcano, Sansonate, El Salvador, is described as Meloidogyne izalcoensis n. sp. The suggested common name is El Salvador coffee root-knot nematode. The perineal pattern is characterised by the moderately high to high, squareish to rounded, dorsal arch, striae coarse, smooth to wavy, sometimes zigzaggy, usually without a distinct whorl, and similar to that of M. incognita and M. paranaensis. The female head region set off from body, sometimes annulated, and the labial disc has two prominent elevations or bumps on the ventral side that are slightly raised above the medial lips. The female stylet is robust, 15.0-16.0 μm long and with the DGO at 4.5-6.0 μm posterior to the knobs. Males have a high, round, head cap continuous with the body contour and the labial disc is fused with the medial lips to form an elongated structure. The head region is never marked by incomplete annulations. The stylet is robust, 23.0-26.0 μm long, and has rounded, backwardly sloping, knobs with the DGO located at 4.0-7.0 μm posteriorly. The stylet of second-stage juveniles is 12.0-13.0 μm long and the DGO is located 3.0-4.0 μm posterior to the stylet base; the tail is 45-48 μm long, conoid, with a rounded terminus. Biochemically, the esterase phenotype I4 (= Sa4) (Rm: 0.86, 0.96, 1.24, 1.30) is unique and is the most useful character to differentiate M. izalcoensis n. sp. from all other species.

Screening of Bacillus thuringiensis strains effective against mosquitoes

The objective of this work was to evaluate 210 Bacillus thuringiensis strains against Aedes aegypti and Culex quinquefasciatus larvae to select the most effective. These strains were isolated from different regions of Brazil and are stored in a Bacillus spp. collection at Embrapa Recursos Geneticos e Biotecnologia, Brasilia, Brazil. The selected strains were characterized by morphological (microscopy), biochemical (SDS-PAGE 10%) and molecular (PCR) methods. Six B. thuringiensis strains were identified as mosquito-toxic after the selective bioassays. None of the strains produced the expected PCR products for detection of cry4, cry11 and cyt1A genes. These results indicate that the activity of mosquitocidal Brazilian strains are not related with Cry4, Cry11 or Cyt proteins, so they could be used as an alternative bioinsecticide against mosquitoes.

Synthesis of polyols and polyurethanes from vegetable oils–kinetic and characterization

The demand of vegetable oils by several sectors of the chemical industry is growing at a fast pace fueled by the fossil oil scarcity, its unpredictable price fluctuations and the ever increasing environmental concerns. The present work reports for the first time the synthesis of polyols and polyurethanes (PUs) from linseed seed (Linum usitatissimun L.) and passion fruit (Passiflora edulis Sims f. flavicarpa Degener) oils. The in situ epoxidation and hydroxylation of vegetable oils in a single step was successfully accomplished using a mixture of hydrogen peroxide (H2O2) and formic acid. Kinetic studies were performed on this system. The oils and the corresponding polyols were characterized by Fourier transform infrared (FT-IR), gel permeation chromatography (GPC) and thermogravimetry (TG)/derivative termogravimetry (DTG). The PUs were characterized by FT-IR, TG/DTG, dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM). The study revealed a marked deviation on the properties between the starting materials and the end products. The PUs produced showed similar dynamic mechanical properties.

Seleção e caracterização de estirpes de Bacillus thuringiensis efetivas no controle da traça-das-crucíferas Plutella xylostella

The aim of this work was to select and characterize the most toxic Bacillus thuringiensis strains, from the Germplasm Bank of Bacillus spp. of Empresa Brasileira de Pesquisa Agropecuaria, against Plutella xylostella. Strains were characterized by morphological, biochemical and molecular methods. It was observed that seven out of the 203 strains tested showed high toxicity compared to the standard used B. thuringiensis subsp. kurstaki (HD-1), which showed 100% mortality. Selected strains showed features described for lepidoptera regarding the protein of 130 kDa and 65 kDa; profile and features were obtained through the PCR reactions, making possible to identify the presence of cry1 and cry2 genes. Moreover, the scanning electron microscopy showed the bipiramydal, cubed and round crystal forms. The selected strains offer new perspectives to control P. xylostella.

Additional information on Meloidogyne inornata Lordello, 1956 (Tylenchida: Meloidogynidae) and its characterisation as a valid species

A root-knot nematode parasitising yakon (Polymia sonchifolia) in Sao Paulo State, Brazil, is identified as Meloidogyne inornata. The species is redescribed from this material and compared with the original description of M. inornata. The female perineal patterns have a distinct, high, dorsal arch composed of smooth to wavy striae, similar to Meloidogyne incognita. The female stylet is 15.0-17.0 ?m long with the cone generally slightly curved dorsally and with well developed knobs. DGO is 3.5-4.5 ?m. Males have a high, rounded, head cap that is continuous with the body contour and has a large, round, centrally concave, labial disc raised above the medial lips. The head region is never marked by incomplete annulations and the stylet is robust, 20.0-25.0 ?m long, with a straight cone, cylindrical shaft with several small projections and pear-shaped, backwardly sloping knobs. The stylet length of second-stage juveniles is 10.0-13.0 ?m, DGO is 2.5-3.5 ?m, tail length is 35.0-58.0 ?m and c = 6.7-13.9. Biochemically, the esterase phenotype I3 (= Y3) is species-specific and is the most useful character for differentiating M. inornata from other Meloidogyne species. Reproduction is by mitotic parthenogenesis, 3n = 54-58. In a soybean test, cv. Abura was susceptible and cv. LA411219 was highly resistant. As the type material is lost, a neotype female is formally designated.