• BMB Reports
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• 제36권3호
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• pp.294-298
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• 2003

The pathological effect of the Bacillus thuringiensis Cry $\delta$-endotoxins on susceptible insect larvae had extensive damage on the midgut epithelial cells. In this study, an ex vivo assay was devised for assessing the insecticidal potency of the cloned Cry4B mosquito-larvicidal protein that is expressed in Escherichia coli. Determination of toxicity was carried out by using a cell viability assay on the midguts that were dissected from 5-day old Aedes aegypti mosquito larvae. After incubation with the toxin proteins, the number of viable epithelial cells was determined photometrically by monitoring the quantity of the bioreduced formazan product at 490 nm. The results showed that the 65-kDa trypsin-activated Cry4B toxin exhibited toxic potency ca. 3.5 times higher than the 130-kDa Cry4B protoxin. However, the trypsin-treated products of the non-bioactive Cry4B mutant (R158A) and the lepidopteran-specific Cry1Aa toxin displayed relatively no ex vivo activity on the mosquito-larval midguts. The ex vivo cytotoxicity studies presented here confirms data that was obtained in bioassays.

• BMB Reports
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• 제43권6호
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• pp.427-431
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• 2010

Cyt2Aa2 is a mosquito-larvicidal protein produced as a 29 kDa crystalline protoxin from Bacillus thuringiensis subsp. darmstadiensis. To become an active toxin, proteolytic processing is required to remove amino acids from its N- and C-termini. This study aims to investigate the functional role of amino acid residues on the N-terminal ${\beta}1$ and C-terminal ${\alpha}F$ of Cyt2Aa2 protoxin. Mutant protoxins were constructed, characterized and compared to the wild type Cyt2Aa2. Protein expression data and SDS-PAGE analysis revealed that substitution at leucine-33 (L33) of ${\beta}1$ has a critical effect on dimer formation and structural stability against proteases. In addition, amino acids N230 and I233-F237 around the C-terminus ${\alpha}F$ demonstrated a crucial role in protecting the protoxin from proteolytic digestion. These results suggested that ${\beta}1$ and ${\alpha}F$ on the Nand C-terminal ends of Cyt2Aa2 protoxin play an important role in the molecular interaction and in maintaining the structural stability of the protoxin.

• 농약과학회지
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• 제4권1호
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• pp.51-58
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• 2000

본 연구는 담배가루이(Bemisia tabaci, B. biotype)의 방제약제를 선발하는 목적으로 시판되고 있는 43종의 살충제에 대한 발육단계별 감수성을 조사하고, 침투이행성, 잔효성 및 방제효과를 평가하였다. 모든 시험은 살충제의 추천농도(ppm)로 수행하였다. 알에 대해서는 IGR계인 pyriproxyfen과 kiflubenzuron이 95%이상의 부화억제효과를 나타내었다. 3령약충에 대해서는 abamectin, acetamiprid, imidacloprid, pyriproxyfen, acetamiprid+ethofenprox이 95%이상의 살충효과를 나타내었다. 그리고 성충에 대해서는 유기인계의 diazinon, fenitrothion, methidathion, pirimiphos-methyl, neonicotinoid계의 acetamiprid, imidacloprid, 혼합제의 acetamiprid+ethofenprox, cartap hydrochloride+buprofezin, fenpropathrin+fenitrothion 기타 abamectin, endosulfan, pymetrozine, spinosad 등이 높은 살충율을 나타내었다. Abamectin, acetamiprid, imidacloprid, pyriproxyfen, acetamiprid+ethofenprox은 성충에 대해서 잔효 성뿐만아니라 침투이행성효과도 나타내었다. 방제효과시험에서 abamectin, acetamiprid, imidacloprid, acetamiprid+ethofenprox 은 처리후 1일째, pyriproxyfen은 처리후 7일째부터 90%이상의 방제효과를 나타내었다. 이상의 결과에서, abamectin, acetamiprid, imidacloprid, pyriproxyfen, acetamiprid+ethofenprox은 담배가루이의 방제에 이용될 수 있을 것으로 생각된다.