3 research outputs found
Toxicity to cotton boll weevil Anthonomus grandis of a trypsin inhibitor from chickpea seeds
Cotton (Gossypium hirsutum L.) is an important agricultural commodity, which is attacked by several pests such as the cotton boll weevil
Anthonomus grandis. Adult A. grandis feed on fruits and leaf petioles, reducing drastically the crop production. The predominance of boll
weevil digestive serine proteinases has motivated inhibitor screenings in order to discover new ones with the capability to reduce the
digestion process. The present study describes a novel proteinase inhibitor from chickpea seeds (Cicer arietinum L.) and its effects against A.
grandis. This inhibitor, named CaTI, was purified by using affinity Red-Sepharose Cl-6B chromatography, followed by reversed-phase
HPLC (Vydac C18-TP). SDS-PAGE and MALDI-TOF analyses, showed a unique monomeric protein with a mass of 12,877 Da. Purified
CaTI showed significant inhibitory activity against larval cotton boll weevil serine proteinases (78%) and against bovine pancreatic trypsin
(73%), when analyzed by fluorimetric assays. Although the molecular mass of CaTI corresponded to a-amylase/trypsin bifunctional
inhibitors masses, no inhibitory activity against insect and mammalian a-amylases was observed. In order to observe CaTI in vivo effects, an
inhibitor rich fraction was added to an artificial diet at different concentrations. At 1.5% (w/w), CaTI caused severe development delay,
several deformities and a mortality rate of approximately 45%. These results suggested that CaTI could be useful in the production of
transgenic cotton plants with enhanced resistance toward cotton boll weevil
Characterization of novel Brazilian Bacillus thuringiensis strains active against Spodoptera frugiperda and other insect pests
Abstract: 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