RESUMO
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 BgNaV1 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.
Assuntos
Inseticidas/farmacologia , Peptídeos/farmacologia , Venenos de Aranha/química , Aranhas/fisiologia , Canais de Sódio Disparados por Voltagem/química , Animais , Blattellidae/efeitos dos fármacos , Dípteros/efeitos dos fármacos , Drosophila melanogaster/efeitos dos fármacos , Avaliação Pré-Clínica de Medicamentos/métodos , Proteínas de Insetos/antagonistas & inibidores , Proteínas de Insetos/metabolismo , Inseticidas/química , Lepidópteros/efeitos dos fármacos , Canal de Sódio Disparado por Voltagem NAV1.5/metabolismo , Peptídeos/genética , Peptídeos/isolamento & purificação , Periplaneta/efeitos dos fármacos , Proteínas Recombinantes/genética , Proteínas Recombinantes/farmacologia , Aranhas/química , Bloqueadores do Canal de Sódio Disparado por Voltagem/farmacologia , Canais de Sódio Disparados por Voltagem/metabolismoRESUMO
Malaria is a mosquito-borne infectious disease caused by Plasmodium parasites transmitted by the infectious bite of Anopheles mosquitoes. Vector control of malaria has predominantly focused on targeting the adult mosquito through insecticides and bed nets. However, current vector control methods are often not sustainable for long periods so alternative methods are needed. A novel biocontrol approach for mosquito-borne diseases has recently been proposed, it uses maternally inherited endosymbiotic Wolbachia bacteria transinfected into mosquitoes in order to interfere with pathogen transmission. Transinfected Wolbachia strains in Aedes aegypti mosquitoes, the primary vector of dengue fever, directly inhibit pathogen replication, including Plasmodium gallinaceum, and also affect mosquito reproduction to allow Wolbachia to spread through mosquito populations. In addition, transient Wolbachia infections in Anopheles gambiae significantly reduce Plasmodium levels. Here we review the prospects of using a Wolbachia-based approach to reduce human malaria transmission through transinfection of Anopheles mosquitoes.
Assuntos
Animais , Humanos , Aedes , Insetos Vetores , Malária , Controle Biológico de Vetores/métodos , Wolbachia/fisiologiaRESUMO
The technique to generate transgenic mosquitoes requires adaptation for each target species because of aspects related to species biology, sensitivity to manipulation and rearing conditions. Here we tested different parameters on the microinjection procedure in order to obtain a transgenic Neotropical mosquito species. By using a transposon-based strategy we were able to successfully transform Aedes fluviatilis (Lutz), which can be used as an avian malaria model. These results demonstrate the usefulness of the piggyBac transposable element as a transformation vector for Neotropical mosquito species and opens up new research frontiers for South American mosquito vectors.