Springer Acta Medica Okayama 0003-6862 54 4 2019 Characterization of the channel-pores formed by Bacillus thuringiensis Cry46Ab toxin in planar lipid bilayers 389 398 EN Akira Sakakibara Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University So Takebe Graduate School of Biology-Oriented Science and Technology, Kindai University Toru Ide Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University Tohru Hayakawa Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University Cry46Ab from Bacillus thuringiensis TK-E6 is a new mosquitocidal toxin with aerolysin-type architecture, and has been shown that co-administration of Cry46Ab with other mosquitocidal Cry toxins results in synergistic toxicity against Culex pipiens Coquillett (Diptera: Culicidae) mosquito larvae. Cry46Ab, therefore, is expected to find use in improving the insecticidal activity of B. thuringiensis-based bioinsecticides. In the present study, the mode of action of Cry46Ab was explored by single-channel measurements of Cry46Ab channel-pores. The single-channel conductances of channel-pores formed in planar lipid bilayers by Cry46Ab were determined to be 31.8 +/- 2.7 pS in 150 mM NaCl and 24.2 +/- 0.7 pS in 150 mM CaCl2. Ion-selectivity measurements revealed that the channel-pores formed by Cry46Ab were cation selective. The permeability ratio of K+ to Cl-was approximately 4, and the preferences for cations were K+ > Na+, K+ > Ca2+, and Ca2+ > Na+. A calcein release assay using liposomes suggested that Cry46Ab influences the integrity of membrane vesicles. Formation of cation-selective channel-pores has been observed with other insecticidal Cry toxins that have structures distinct from those of Cry46Ab; the capability of forming such pores may be a property required of insecticidal toxins. No potential conflict of interest relevant to this article was reported.

Faculty of Engineering, Okayama University Acta Medica Okayama 0475-0071 38 1-2 2004 Serration and Reversion Treatment in Al-10mass%Zn Alloy 1 4 EN Akira Sakakibara Teruto Kanadani 10.18926/46946 The relationship between occurrence of serration and reversion heat treatment was studied by tensile test on Al-10mass%Zn alloy. Serration was observed for the furnace cooled specimen, but not for the as-quenched one and the shortly aged one, which result is difficult to be interpreted by the Cottrell theory. The stress amplitude in the serration increased with increasing the time of annealing for reversion up to 10ks and then stayed at a constant value which might be interpreted by the Cottrell theory. The stress amplitude in the serration decreased with increasing the annealing temperature, which is contrary to the prediction by the Cottrell theory. The specimen directly annealed without aging and the one annealed after aging agreed well with each other in the tensile strength and the stress amplitude in the serration, which suggests solute clusters as the cause of serration. No potential conflict of interest relevant to this article was reported.