Molecular basis of the remarkable species selectivity of an insecticidal sodium channel toxin from the African spider Augacephalus ezendami

The inexorable decline in the armament of registered chemical insecticides has stimulated research into environmentally-friendly alternatives. Insecticidal spider-venom peptides are promising candidates for bioinsecticide development but it is challenging to find peptides that are specific for targeted pests. In the present study, we isolated an insecticidal peptide (Ae1a) from venom of the African spider Augacephalus ezendami (family Theraphosidae). Injection of Ae1a into sheep blowflies (Lucilia cuprina) induced rapid but reversible paralysis. In striking contrast, Ae1a was lethal to closely related fruit flies (Drosophila melanogaster) but induced no adverse effects in the recalcitrant lepidopteran pest Helicoverpa armigera. Electrophysiological experiments revealed that Ae1a potently inhibits the voltage-gated sodium channel BgNa V 1 from the German cockroach Blattella germanica by shifting the threshold for channel activation to more depolarized potentials. In contrast, Ae1a failed to significantly affect sodium currents in dorsal unpaired median neurons from the American cockroach Periplaneta americana. We show that Ae1a interacts with the domain II voltage sensor and that sensitivity to the toxin is conferred by natural sequence variations in the S1-S2 loop of domain II. The phyletic specificity of Ae1a provides crucial information for development of sodium channel insecticides that target key insect pests without harming beneficial species

Abordagem sócio-histórica sobre a evolução da assistência ao parto num município de médio porte de Minas Gerais (1960-2001)

Trata-se de caracterizar a evolução da série histórica quanto ao tipo de parto, normal, cesárea e fórceps, no período de 1960 a 2001, nas três maternidades mais antigas e conveniadas ao Sistema Único de Saúde (SUS) de Juiz de Fora. O método utilizado denomina-se história serial e permite a comparabilidade entre eventos históricos em determinado período de tempo. Foi identificado o aumento de incorporação tecnológica nesta trajetória e o crescente uso da cesariana até 1998, quando se identifica o impacto da portaria nº 2816, proposta pelo Ministério da Saúde, através de inversão dessa tendência com elevação do número de partos normais. A diferenciação constatada do tipo de parto de acordo com a categoria de internação aponta para uma discussão marcadamente política, que diz respeito às relações sociais em que se entrelaçam desigualdades de diversas ordens, entre elas as de gênero e de classe social. Conhecer as desigualdades e problematizar sua existência, traduzida em perfis de morbimortalidade e padrões desiguais de assistência, é precondição para obter o encaminhamento da solução

Chemical composition and antifungal activity of essential oil from Eucalyptus smithii against dermatophytes

ABSTRACT INTRODUCTION: In this study, we evaluated the chemical composition of a commercial sample of essential oil from Eucalyptus smithii R.T. Baker and its antifungal activity against Microsporum canis ATCC 32903, Microsporum gypseum ATCC 14683, Trichophyton mentagrophytes ATCC 9533, T. mentagrophytes ATCC 11480, T. mentagrophytes ATCC 11481, and Trichophyton rubrum CCT 5507. METHODS: Morphological changes in these fungi after treatment with the oil were determined by scanning electron microscopy (SEM). The antifungal activity of the oil was determined on the basis of minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) values. RESULTS: The compound 1,8-cineole was found to be the predominant component (72.2%) of the essential oil. The MIC values of the oil ranged from 62.5μg·mL−1 to >1,000μg·mL−1, and the MFC values of the oil ranged from 125μg·mL−1 to >1,000μg·mL−1. SEM analysis showed physical damage and morphological alterations in the fungi exposed to this oil. CONCLUSIONS: We demonstrated the potential of Eucalyptus smithii essential oil as a natural therapeutic agent for the treatment of dermatophytosis