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Publication Open Access Structural basis of pore formation by mosquito-larvicidal proteins from bacillus thuringiensis(2010-01) Chanan Angsuthanasombat; Mahidol University. Institute of Molecular BiosciencesThe insecticidal character of the three-domain Cry -endotoxins produced by Bacillus thuringiensis during sporulation is believed to be caused by their capability to generate lytic pores in the target larval midgut cell membranes. This review... describes toxic mechanisms with emphasis on the structural basis of pore formation by two closely related dipteran-specific toxins, Cry4Aa and Cry4Ba, which are highly toxic to mosquito larvae. One proposed toxic mechanism via an “umbrella-like” structurePublication Open Access Cloning of a chitinase gene into Bacillus thuringiensis subsp. aizawai for enhanced insecticidal activity(1997-12) Tantimavanich S; Pantuwatana S; Bhumiratana A; Panbangred W; Faculty of Science. Department of BiotechnologyChitinase from a high producing strain (TP-1) of Bacillus licheniformis was used with B. thuringiensis subsp. aizawai (B.t.a.) in a combined larvicidal assay against the pest, Spodoptera exigua. With 10 mU of this chitinase, the LD(50) of B.t.a. was reduced by 7.6, 13.8 and 15 times on days 3, 5 and 7, respectively when compared to use of B.t.a. alone. In addition, a combination of chitinase (10 mU) and B.t.a. at a sub-lethal dose retarded growth and development of S. exigua. In preparation for transformation of B.t.a., the TP-1 chitinase gene was cloned in E. coli DH5alpha and sequenced to reveal a single open reading frame of 1,815 bp. This open reading frame encoded for a protein of 604 amino acids and a characteristic signal peptide sequence of 35 amino acids. The gene was subsequently introduced into B.t.a. where it was expressed constitutively. The transformed strain showed slightly improved activity against S. exigua when compared to the non-transformed strain. This was probably due to the low chitinase activity (15 mU/ml) of the transformant, which might be improved by further gene manipulation to overexpress enzyme production.Publication Open Access Functional characterizations of residues Arg-158 and Tyr-170 of the mosquito-larvicidal Bacillus thuringiensis Cry4Ba(2014) Somphob Leetachewa; Saengduen Moonsom; Urai Chaisri; Narumol Khomkhum; Nonglak Yoonim; Wang Ping; Chanan Angsuthanasombat; Mahidol University. Institute of Molecular Biosciences; Mahidol University. Faculty of Tropical Medicine. Department of Tropical PathologyThe insecticidal activity of Bacillus thuringiensis (Bt) Cry toxins involves toxin stabilization, oligomerization, passage across the peritrophic membrane (PM), binding to midgut receptors and pore-formation. The residues Arg-158 and Tyr-170 have... been shown to be crucial for the toxicity of Bt Cry4Ba. We characterized the biological function of these residues. In mosquito larvae, the mutants R158A/E/Q (R158) could hardly penetrate the PM due to a significantly reduced ability to alter PMPublication Open Access Isoleucine at position 150 of Cyt2Aa toxin from Bacillus thuringiensis plays an important role during membrane binding and oligomerization(2013) Wanwarang Pathaichindachote; Amporn Rungrod; Mongkon Audtho; Sumarin Soonsanga; Chartchai Krittanai; Boonhiang Promdonkoy; Mahidol University. Institute of Molecular BiosciencesCyt2Aa2 is a mosquito larvicidal and cytolytic toxin produced by Bacillus thuringiensis subsp. darmstadiensis. The toxin becomes inactive when isoleucine at position 150 was replaced by alanine. To investigate the functional role of this position, Ile150 was substituted with Leu, Phe, Glu and Lys. All mutant proteins were produced at high level, solubilized in carbonate buffer and yielded protease activated product similar to those of the wild type. Intrinsic fluorescence spectra analysis suggested that these mutants retain similar folding to the wild type. However, mosquito larvicidal and hemolytic activities dramatically decreased for the I150K and were completely abolished for I150A and I150F mutants. Membrane binding and oligomerization assays demonstrated that only I150E and I150L could bind and form oligomers on lipid membrane similar to that of the wild type. Our results suggest that amino acid at position 150 plays an important role during membrane binding and oligomerization of Cyt2Aa2 toxin. [BMB Reports 2013; 46(3): 175-180]Item Open Access คู่มือปฏิบัติงานเรื่อง การให้คำปรึกษาและการให้ข้อมูลด้านพิษวิทยา : ภาวะพิษจากสารเคมีที่พบบ่อย(2564) ฐิติพล เยาวลักษณ์; มหาวิทยาลัยมหิดล. คณะแพทยศาสตร์ศิริราชพยาบาล. งานวิชาการเภสัชกรรมPublication Open Access Interaction of Omega, Sigma, and Theta glutathione transferases with p38b mitogen-activated protein kinase from the fruit fly, Drosophila melanogaster.(2014) Wongtrakul, J.; Janphen, K.; Saisawang, C.; Ketterman, AJ.; Mahidol University. Institute of Molecular BiosciencesGlutathione S-transferases (GSTs) are a diverse family of phase II detoxification enzymes found in almost all organisms. Besides playing a major role in the detoxification of xenobiotic and toxic compounds, GSTs are also involved in the regulationPublication Open Access Acaricidal activity of Thai medicinal plants(2005) Noppamas Soonthornchareonnon; Vanna Mahakittikun; Wongsatit Chuakul; Kanisa Rongsriyam; นพมาศ สุนทรเจริญนนท์; วงศ์สถิตย์ ฉั่วกุล; Mahidol University. Faculty of Pharmacy. Department of Pharmacognosy.; Mahidol University. Faculty of Pharmacy. Department of Pharmaceutical Botany.; Mahidol University.Faculty of Medicine Siriraj Hospital. Department of Parasitology%) and Erythrophleum succirubrum (stem, 55%) which were tested at the applied amount of 2.40 mg/cm2. However, T. reidioides and A. pedunculata showed the high toxicity in the brine shrimp microwell toxicity assay with the lethal concentration (LD50) of 6 and 0.2 μg/ml..., respectively. E. succirubrum and A. indica showed less toxicity (LD50 = 245 and 233 μg/ml, respectively). Thus E. succirubrum and A. indica are promising to be used as natural product acaricides for controlling house dust mites due to their high acaricidalPublication Open Access Efficient transcription of the larvicidal cry4Ba gene from Bacillus thuringiensis in transgenic chloroplasts of the green algal Chlamydomonas reinhardtii(2012-08) Thanate Juntadech; Kittisak Yokthongwattana; Sithichoke Tangphatsornruang; Yun-kiam Yap; Gerd Katzenmeier; Chanan Angsuthanasombat; Mahidol University. DivisionInstitute of Molecular Biosciences; Mahidol University. Faculty of Science. Department of Biochemistry and Center for Excellence in Protein Structure and Functiondemonstrates the sufficiency of this system’s transcription machinery, offering the further innovation for insecticidal protein production.Publication Open Access Mass primaquine treatment to eliminate vivax malaria: lessons from the past(2014) Anatoly Kondrashin; Baranova, Alla M; Ashley, Elizabeth A; Judith Recht; White, Nicholas J; Sergiev, Vladimir P; Mahidol University. Faculty of Tropical Medicine. Mahidol-Oxford Tropical Medicine Research Unitand adequate medical support to manage haemolytic toxicity, it is possible to achieve high population coverage, substantially reduce malaria transmission, and manage the risk of severe acute haemolytic anaemia in communities with a relatively high prevalencePublication Open Access Accumulation and distribution of some heavy metals in water, soil and rice fields along the Pradu and Phi Lok Canals, Samut Songkhram Province, Thailand(2011-04) Roongrawee Kingsawat; Raywadee Roachanakanan; Raywadee Roachanakanan; Mahidol University. Faculty of Environment and Natural Resource StudiesThis study aims to determine concentrations of heavy metals (Cd, Cu, and Zn) in the water, soil, and rice in paddy fields, and to compare heavy metal concentrations in the water, soil, and four parts of the rice plant (root, shoot, grain, and husk) between organic paddy fields and conventional paddy fields. The study area was the Pradu Canal (sites A and C) and the Phi Lok Canal (site B) in Phraek Nam Daeng Sub-district, Samut Songkhram Province, Thailand. Data was collected from August 2007 to December 2007. The water, soil, and rice samples were prepared for heavy metal analysis using a microwave digestion system and heavy metal concentrations were determine d using an atomic absorption spectrophotometer. Physicochemical parameters of the water and soil were also study. The results showed the accumulation of heavy metals in the water, paddy soil, and four parts of the rice plant to be as follows (in descending order of frequency): Zn > Cu >Cd. The concentration of heavy metals in samples was also found to be as follows(greatest first): paddy soil > rice root > rice shoot > rice grain > rice husk > water. Nosignificant difference was observed between Cd and Zn in paddy soil before ploughingand after rice harvesting at sites A, B, and C. However, Cu showed a significantdifference at the level of 0.05 at site A and no significant difference at sites B and C. It can be concluded therefore that Cd, Cu, and Zn concentrations in paddy soil and water were lower than the values permitted by the Surface Water Quality Standard and Soil Quality Standard of Thailand. Furthermore, Cd concentrations in rice seeds were lower than the values permitted by international health organizations and thus acceptable for human consumption.