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The reproductive behaviour of the root-knot nematode Meloidogyne arenaria race 1 was compared on two wild species of Arachis ( A. duranensis and A. stenosperma ) and cultivated peanut ( A. hypogaea cv. IAC-Tatu-ST). The three species were considered moderately susceptible, resistant, and susceptible, respectively. Penetration and development of the root-knot nematode in the resistant species was reduced in comparison with that occurring in susceptible plants. Several cell features, including dark blue cytoplasm and altered organelle structure were observed in the central cylinder of A. stenosperma , indicating a hypersensitive-like response (HR) of infested host cells. Neither giant cells, nor nematodes developed beyond the second stage, were found on A. stenosperma. Arachis duranensis showed a delay in the development of nematodes in the roots compared to A. hypogaea. The two wild peanut species were chosen to be the contrasting parents of a segregating population for mapping and further investigation of resistance genes.

Antimicrobial peptides form part of the first line of defense against pathogens for many organisms. Current treatments for fungal infections are limited by drug toxicity and pathogen resistance. Cm-p5 (SRSE-LIVHQRLF), a peptide derived from the marine mollusk Cenchritis muricatus peptide Cm-p1, has a significantly increased fungistatic activity against pathogenic Candida albicans (minimal inhibitory concentration, 10 mg/ml; EC 50 , 1.146 mg/ml) while exhibiting low toxic effects against a cultured mammalian cell line. Cm-p5 as characterized by circular dichroism and nuclear magnetic resonance revealed an a-helical structure in membranemimetic conditions and a tendency to random coil folding in aqueous solutions. Additional studies modeling Cm-p5 binding to a phosphatidylserine bilayer in silico and isothermal titration calorimetry using lipid monophases demonstrated that Cm-p5 has a high affinity for the phospholipids of fungal membranes (phosphatidylserine and phosphatidylethanolamine), only moderate interactions with a mammalian membrane phospholipid, low interaction with ergosterol, and no interaction with chitin. Adhesion of Cm-p5 to living C. albicans cells was confirmed by fluorescence microscopy with FITC-labeled peptide. In a systemic candidiasis model in mice, intraperitoneal administration of Cm-p5 was unable to control the fungal kidney burden, although its low amphiphaticity could be modified to generate new derivatives with improved fungicidal activity and

Resumo -O objetivo deste trabalho foi selecionar entre 300 estirpes de Bacillus thuringiensis as efetivas simultaneamente contra larvas de Spodoptera frugiperda J.E. Smith e Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae), Anthonomus grandis Boheman (Coleoptera: Curculionidae), Aedes aegypti Linnaeus e Culex quinquefasciatus Say (Diptera: Culicidae). Foram selecionadas duas estirpes de B. thuringiensis, denominadas S234 e S997, que apresentaram atividade contra as três ordens de insetos. As estirpes foram caracterizadas por métodos morfológicos, bioquímicos e moleculares. As mesmas apresentaram duas proteínas principais de 130 e 65 kDa, produtos de reação em cadeia da polimerase de tamanho esperado para a detecção dos genes cry1Aa, cry1Ab, cry1Ac, cry1B e cry2 e cristais bipiramidais, cubóides e esféricos.Termos para indexação: larva, controle biológico, proteína, reação em cadeia da polimerase, combate às pragas, biopesticida. Bacillus thuringiensis strains effective against insects of Lepidoptera, Coleoptera and Diptera ordersAbstract -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 Hübner (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.Index terms: larvae, biological control, protein, polymerase chain reaction, pest control, biopesticides. IntroduçãoCerca de 15% da safra de alimentos do mundo é perdida por causa do ataque de insetos, cujo controle tem sido feito, predominantemente, com uso de inseticidas químicos (Silva-Filho & Falco, 2000). Inseticidas quími-cos são altamente tóxicos e de amplo espectro de ação com conseqüências graves ao homem e ao meio ambiente, além de causar o aparecimento de populações de insetos resistentes. Portanto, é necessário reduzir o uso desses produtos mediante o emprego de alternativas mais seguras de controle. Assim, os agentes de controle biológico, principalmente as bactérias, são uma alternativa econômica e ecologicamente viável.Dentre as bactérias utilizadas no controle biológico, Bacillus thuringiensis é responsável por 90%-95% do mercado de bioinseticidas (Valadares-Inglis et al., 1998) e apresenta ampla distribuição, podendo ser encontrada em praticamente todos os ambientes. Além disso, produz diferentes proteínas tóxicas, denominadas cristais, altamente específicas para os insetos das ordens Lepidoptera, Coleoptera e Diptera e não afetam o homem, os animais e as plantas (Souza et a...

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