• Food Science and Biotechnology
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• v.15 no.4
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• pp.625-630
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• 2006

Polymerase chain reaction (PCR) method was developed for the specific detection of insect-resistant rice containing cry1Ac gene derived from Bacillus thuringiensis (Bt). Primers were designed from the 35S promoter, NOS terminator, cry1Ac gene, and sucrose phosphate synthase (SPS) for general screening of Bt rice. By sequencing the PCR products from the two putative kinds of Bt rice, we designed a specific primer from the junction region between the cry1Ac gene and the NOS terminator that had been inserted into Bt rice. The construct-specific primer was employed to amplify a 147 bp product in the two lines of Bt rice. No amplified products were observed from the other Bt crops with various Bt genes introduced. In qualitative PCR analysis, the limit of detection was 0.005 ng from genomic DNA of Bt rice. In addition, PCR analysis was performed on 64 kinds of rice presently available in the Korean market, and no Bt rice was detected. This method presented in this paper can be used as a highly sensitive and specific detection method of Bt rice.

• International Journal of Industrial Entomology and Biomaterials
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• v.14 no.1
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• pp.33-36
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• 2007

To improve insecticidal activity of B. thuringiensis 2385-1 (Bt 2385-1), a recombinant plasmid, pHT1K-1Ac, was introduced into lepidopteran toxic Bt 2385-1 by electroporation. The presence of the recombinant plasmid in Bt 2385-1 after electroporation was confirmed by PCR. Bt 2385-1 transformant was named as Bt pHT1K-1Ac/2385-1 (1K-1Ac/2385-1). The 1K-1Ac/2385-1 transformant produced bipyramidal-shaped parasporal inclusion as like the wild-type strain, Bt 2385-1, and showed an 130 kDa band of Cry1Ac protein. The insecticidal activity of 1K-lAc/2385-1 against S. exigua was similar to that of Bt 2385-1 but the $LC_{50}$ value of transformant against P. xylostella was 1.8 times lower. Through these bioassay results, it was confirmed that toxicity of Bt 2385-1 transformant showed synergistic effect by introducing Cry1Ac. These results suggested that the multiple expressions of Cry proteins in a promising Bt strain may interact synergistically in insect midgut, resulting in increase of toxicity and expansion of host spectrum.

• The Journal of the Petrological Society of Korea
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• v.6 no.1
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• pp.34-44
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• 1997

The Jurassic granites, commercially called Yangu stone in the Pocheon-Euijeongbu area, have generally compact and coarse-grained textures, which could be classified into two types; grey granite(Gg) and light pink granite(Gp). Specific gravity, absorption ratio and prosity of Gg and Gp in physical property are 2.64 and 2.61, 0.32 % and 0.44 %, 0.86% and 1.13 %, respectively. These higher values of two latters of Gp than those of Gg are due to the more abundant microcracks in Gp. Compressive strength og Gg than those of Gg are due to more abundant microcracks in Gp. Compressive strength og Gg and Gp are 1,726 kg/cm2 and 1,717 kg/cm, respectively and bestrength has a positive proportion with Qz+Af+Pl(quartz+alkali feldspar+plagioclase) modes without trending with Bt+Ac(biotite+accessories). Tensile strength has the positive proportions with Qz+Af+Pl and Bt+Ac. While Bt+Ac has a negative trend with abrasive hardness, Qz+A+Pl shows a positive one. These may suggest Qz+Af+Pl mainly affects on strenghts potentional dimension stone than Gp.

• Journal of the Korean Society of International Agriculture
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• v.23 no.5
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• pp.570-577
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• 2011

We developed insect-resistant GM rice(Bt transgenic rice) by inserting the mCry1Ac1 a modified gene from the soil bacterium, Bacillus thuringiensis. The Bt transgenic rice expressing the Bttoxin mCry1Ac1 was tested for the effects on survival of Misgurnus anguillicaudatus and Cyprinus carpio, commonly used as a model organism in ecotoxicological studies. M. anguillicaudatus and C. carpio fed 100% ground rice in suspension, using either Bt rice or non-GM counterpart rice(Nakdong). The Bt rice used for the test were confirmed to have the mCry1Ac1 gene expression by the immuno-strip and ELISA analysis. Feeding test showed that no significant differences in cumulative immobility and abnormal response of M. anguillicaudatus and C. carpio fed on between Bt rice and non-GM counterpart rice. The 96hr-LC₅₀ values showed no difference between Bt rice(>1,000mg/L) and non-GM rice(>1,000mg/L). We concluded that there was no significant difference in toxicity for non-target organisms(M. anguillicaudatus and C. carpio) between Bt rice and non-GM counterparts.

• Journal of the Korean Society for Railway
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• v.18 no.3
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• pp.241-251
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• 2015

Compared with ballasted track (BT), ballasted asphalt track (BAT) has been increasingly adopted in many countries due to its more greatly reduced reinforced roadbed thickness and smaller cumulative plastic deformation, and its advantages in terms of maintenance. In this respect, the authors' previous research includes analysis of BAT sections that show performance similar to that of BT sections of the present specifications; reliability verification of the analysis results through real-sized static and dynamic train-load tests were performed. Based on previous research, this paper estimates the track lifetime using the strain of the lower roadbed according to reinforced roadbed thickness; using probabilistic LCC analysis, this paper presents a BAT section that satisfies the design lifetime and that has performance similar to or higher than that of BT.

• Plant Biotechnology Reports
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• v.3 no.4
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• pp.317-324
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• 2009

The insecticidal toxin gene of Bacillus thuringiensis (Bt) is one of the most commonly used in the development of genetically modified (GM) crops. In this research, we analyzed Bt rice showing lepidopteran pest-resistance. The Bt gene is a synthetic Cry1Ac composed of optimal codons for plants, and the Bt protein is targeted to the chloroplast by a transit peptide. Three Cry1Ac rice events (C103-3, C127-1, and C7-1) were analyzed for molecular characterization. C103-3 contains two copies of T-DNA where the left border (LB) region is truncated. Both C7-1 and C127-1 have a single copy of T-DNA, but a part of the vector backbone DNA is inserted into the genome of C127-1; thus, only C7-1 had intact T-DNA. Progenies of C7-1 crossed with the original cultivar, Nakdong, and double-haploid lines from anther culture of lines crossed with the elite cultivar, Dongjin, were analyzed for T-DNA flanking genomic DNA and genotyping. Results showed that an intact T-DNA region without the vector backbone was inserted into the genome and was stably inherited through generations. The C7-1 homozygous event could be used as breeding material to develop GM rice with pest resistance.

• The Journal of Korean Society of Virology
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• v.29 no.3
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• pp.145-153
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• 1999

We have now constructed a novel recombinant baculovirus Autographa californica nuclear polyhedrosis virus (AcNPV) producing polyhedra with Bacillus thuringiensis (Bt) CryIAc crystal protein. The recombinant polyhedra produced by the recombinant baculovirus, Btrus, in insect cells was characterized. The recombinant baculovirus has two independent transcription units in opposite orientations with two promoters, p10 or polyhedrin gene promoter each initiating transcription of either native polyhedrin or fusion protein with polyhedrin and Bt Cry1Ac crystal protein. Surprisingly, this recombinant baculovirus stably produced recombinant polyhedra which were nearly similar to those of wild-type AcNPV. The immunogold staining experiment showed that the recombinant polyhedra were assembled with polyhedrin and Bt Cry1Ac crystal protein, and contained virus particles. Insecticidal toxicity of recombinant polyhedra of Btrus to the fall webworm, Hyphantria cunea, was strikingly improved in comparison with the wild-type AcNPV.

• Korean journal of applied entomology
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• v.36 no.4
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• pp.341-350
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• 1997

We have now constructed a novel recombinant baculovirus producing fusion protein with Autographa californica nuclear polyhedrosis virus (AcNPV) polyhedrin and Bacillus thuringiensis(Bt) cryIA(c) crystal protein. The fusion protein expressed by the recombinant baculovirus in insect cells was characterized. The N-terminal of cryIA(c) gene of Bt subsp. kurstaki HD-73 was introduced under the control of polyhedrin gene promoter of AcNPV, by fusion in the front of intact polyhedrin gene or by insertion into the HindIII site in polyhedrin gene. The recombinant baculoviruses were named as BtrusI or BtrusII, respectively. Although single transcript from the fusion protein gene was apparently observed. BtrusI was produced the two proteins, 92 kDa fusion protein and only polyhedrin. In addition, fusion protein produced by BtrusI did not form polyhedra. Interestingly, however, the cells infected with BtrusII did not show a 33 kDa polyhedrin band as a cells infected with BtrusI. Cells infected with BtrusII were only produced fusion protein, but the polyhedra formed by fusion protein was not observed. To determine the insecticidal toxicity of fusion protein, therefore, Sf9 cells infected with BtrusI were inoculated to Bombyx mori larvae. Sf9 cells infected with BtrusI that expressed the fusion protein caused larval mortality although the insecticidal toxicity was low. In conclusion, our results clearly demonstrated that the fusion protein with polyhedrin and Bt cryIA(c) crystal protein have a insecticida toxicity.

• Korean Journal of Agricultural Science
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• v.46 no.1
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• pp.113-124
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• 2019

Insect-resistant transgenic (Bt-9) rice was generated by inserting mCry1Ac1, a modified gene from the soil bacterium Bacillus thuringiensis, into the genome of a conventional variety of rice (Ilmi). With regard to potential problems such as safety, an evaluation of non-target organisms is necessary as an essential element of an environmental risk assessment of genetically modified (GM) crops. We studied the effects of the Bt-9 rice on the survival of cantor Daphnia magna, a commonly used model organism in ecotoxicological studies. D. magna fed on the Bt-transgenic rice (Bt-9) and its near non-GM counterparts (Ilmi) grown in the same environment (a 100% ground rice suspension). The Bt-9 rice was confirmed to have the inserted T-DNA and protein expression evident by the PCR and ELISA analyses. The feeding study showed a similar cumulative immobility and abnormal response of the Daphnia magna between the Bt-9 rice and Ilmi. Additionally, the 48 h-EC50 values of the Bt-9 and Ilmi rice were 4,400 mg/L (95% confidence limits: 3861.01 - 5015.01 mg/L) and 5,564 mg/L (95% confidence limits: 4780.03 - 6476.93 mg/L), respectively. The rice NOEC (No observed effect concentration) value for D. magna was suggested to be 1,620 mg/L. We conclude that the tested Bt-9 and Ilmi have a similar cumulative immobility for D. magna, a widely used model organism, and the growth of Bt-9 did not affect non-target insects.

• The Korean Journal of Pesticide Science
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• v.18 no.3
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• pp.181-190
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• 2014

An entomopathogenic bacterium, Bacillus thuringiensis (Bt), can sporulate along with production of insecticidal Cry toxins. Bt Cry toxins exhibit relatively narrow spectrum to target insects due to their specific interactions with midgut receptors. This study designed several strategies to enhance Bt efficacy in target insect spectrum and insecticidal activity. Four Cry toxins were purified from four different Bt strains and showed relatively narrow target insect spectrum. However, the Cry mixtures significantly expanded their target insect spectra. The additional effect of baculovirus to Cry toxin was tested with recombinant baculoviruses expressing Cry1Ac or Cry1Ca. However, the baculovirus was little effective to expand target insect spectrum. Bacterial culture broth of Xenorhabdus nematophila (Xn) significantly suppressed insect cellular immune response and increased Cry toxicity. The addition of Xn culture broth to Cry mixture significantly enhanced Bt efficacy in target insect spectrum and insecticidal activity.