• Horticultural Science & Technology
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• v.17 no.4
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• pp.473-475
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• 1999

This study was carried out to restore the fertility by suppression of male sterility-induced gene using an antisense construct. Tobacco (cv. Petit Havana SR1) was transformed with the binary vector containing a GBAN215-6 promoter, an antisense diphtheria toxin (DTx-A) gene (pKDA215b) and a hygromycin resistant gene. Seventy-six confirmed transgenic plants regenerated from leaf disks were designated as the $R_0$ generation and selfed to produce the $R_1$ generation. From the inheritance study, five $R_1$ lines with multiple copies of the antisense construct were selected and selfed to identify homozygosity for the antisense construct. In order to restore fertility and finally to select restore lines, five $R_2$ lines with multiple copies of the antisense construct were crossed with male sterile plants. From these crosses, three different phenotypes have been observed: completely restored, partially restored, and not restored pollens, and otherwise tobacco plants were phenotypically same as normal plants. These plants were scored for the degree of restoration and selected for further study.

• Korean Journal of Animal Reproduction
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• v.27 no.2
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• pp.179-185
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• 2003

To determine whether the diphtheria toxin-A (DT) gene disrupts development of thymocytes in transgenic animal, the DT-A gene was used for the production of transgenic mice directed by proximal Ick promoter sequences. Two transgenic founder mice that contained several copies of transgene were produced by DNA microinjection and integration of transgene in transgenic mice was confirmed by PCR and Southern blotting analysis. Transgenic $F_1$ and $F_2$ mice were produced by outbreeding of founder and $F_1$ mice to investigate expression of transgene and phenotypes in transgneic mice. Expression of the diphtheria toxin gene was confirmed in thymus, spleen and liver of transgenic mice by RT-PCR. In circulating blood of transgenic mice, lower number of circulating white blood cells and platelets were observed compared with that of normal mice. In addition, transgneic mice had reduced number of circulating peripheral T-cells analyzed by FACS with anti-CD3 antibody. The data in these transgenic mice indicate that DT gene can play a disruptive role in developing thymocytes of transgenic mice resulted in lower number of T-cells that can be applicable to a wide range of tissues in other animals.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.21 no.3
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• pp.141-146
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• 2010

This summary of literature during the past year reviews published studies relating to risk factors for depressive disorders in children and adolescents. Risk factors include environmental toxins, socio-environmental, and genetic factors. As depression has a complex, multifactorial causal mechanism, it is likely that the accumulation and/ or interaction among multiple risk factors lead to depression. Findings related to the result of toxin exposure have been difficult to interpret given that risk factors tend to interact and that higher mental functions are not easily measurable. However, some findings have been consistent. Clinical research data has also shown that the risk for negative outcomes may be modified both by genetic and environmental factors through a gene environment interplay mechanism.

• BMB Reports
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• v.36 no.5
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• pp.508-513
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• 2003

The bacterium Bacillus thuringiensis produces toxin inclusions that are deleterious to target insect larvae. These toxins are believed to interact with a specific receptor protein(s) that is present on the gut epithelial cells of the larvae. In various insect species (in particular those belonging to the lepidopteran class), aminopeptidase N (APN) is one of the two receptor proteins that are considered to be involved in toxin-receptor interactions. However, in mosquitoes, the nature and identity of the receptor protein is unknown. Here, using RT-PCR, we identified two isoforms of the APN transcripts in the Aedes aegypti mosquito larval midgut. These results are congruent with a previous report of multiple isoforms of the APN gene expression in lepidopteran larvae. Which of the two isoforms (or other yet unidentified receptor proteins) is involved in the killing of mosquito larvae remains to be elucidated.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1986.12a
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• pp.515.2-515
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• 1986

B. sphaericus 1593 K-5 synthesize a potent entomicidal toxin against mosquito larvae. B. sphaericus EcoRl DNA fragment carrying the biocidal activity was clonied and expression in E. coli JM83. For the construction of a recombinant plasmid bearing the toxin activity the DNA of B. sphaericus was partially digested by the EcoRl. The EcoRl DNA fragments were ligated to plasmid pUC 8-EcoR1 site. The transformants were selected on LB plates containing X-gall and ampicilline. The transformants were bioassayed against mosquito larvae of which two clones showed biocidal activity. The two clones were redigested with Eco R1 and analyzed by 0.7% agarose gel electrophorsis.

• Journal of Microbiology and Biotechnology
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• v.14 no.4
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• pp.772-776
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• 2004

Physiological and molecular characteristics of Bacillus thuringiensis SR6 and SR8 were investigated, and phase contrast and electron microscopies revealed that a large rhomboidal crystal protein was present in the sporulating cells. SDS-PAGE and Western blot analyses showed that B. thuringiensis SR8 produced 70 kDa protein much more than other proteins, and that the 70 kDa protein could bind to the antibody of B. thuringiensis subsp. tenebrionis-crystal toxin protein, indicating that the crystal 70 kDa protein has an immunological homology with B. thuringiensis subsp. tenebrionis-crystal toxin protein. The DNA fragment of B. thuringiensis subsp. tenebrionis-toxin gene was detected in B. thuringiensis SR6 and SR8 by using PCR amplification analysis. Furthermore, the insect bioassay showed the insecticidal activity against Colorado potato beetle larvae. Based on the physiological and molecular similarities to B. thuringiensis subsp. tenebrionis, it is suggested that the B. thuringiensis SR6 and SR8 may be mutants of the B. thuringiensis subsp. tenebrionis strain overexpressing the crystal of 70 kDa toxin protein.

• Korean Journal of Microbiology
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• v.54 no.1
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• pp.1-8
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• 2018

A prokaryotic cell has various histone-like proteins also known as nucleoid-associated proteins (NAPs). These proteins bind AT-rich sequence at DNA, which induce DNA wrapping, bending, and bridging, and subsequently regulate the gene expression in bacteria. Because NAPs function in transcriptional silencing of virulence genes, it is important to study their roles in gene silencing and specific mechanisms of these proteins. In this review, we discussed two well-known NAPs, H-NS, and HU, and summarized their roles for gene expression in Escherichia coli and Salmonella Typhimurium. Through the oligomerization and filamentation of H-NS, it represses the expression of virulence genes in human pathogenic bacteria, such as Salmonella Typhimurium, and it works with other NAPs positively or negatively. Recently, H-NS also regulates typhoid toxin expression, which causes typhoid fever and systemic disease in human. Additionally, HU regulates the expression of genes related to both virulence and physiology of Salmonella. Therefore, we suggest that NAPs like H-NS and HU are crucial factors to reveal the molecular mechanisms of virulence gene expression in bacteria.

• Korean Journal of Veterinary Service
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• v.39 no.2
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• pp.87-92
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• 2016

Porcine edema disease (ED) is a communicable disease of pigs caused by infection with Shiga toxin (Stx)-producing Escherichia coli (STEC) which expresses F18 fimbriae and/or Stx type 2e (Stx2e). While STEC causes a severe illness including hemorrhagic colitis and hemolytic-uremic syndrome in humans, it induces damage to the vascular endothelium, which results in edema, hemorrhage, and microthrombosis, leading in high mortality in pigs. In the present study, we cultured Stx2e-producing E. coli field isolates from conventional pig farms that experienced sudden deaths previously with symptoms similar to porcine edema disease, which were further investigated with Shiga toxin profiles. A total of 43 strains were identified from the collected samples by F18 or Stx2e specific PCR. Based on the PCR, 42 isolates out of 43 isolates were proved to carry one of F18 or Stx2e genes and 14 isolates to carry both F18 and Stx2e genes. All of the 30 isolates that harbored Stx2e gene induced the cytopathic effect (CPE) in vero cells and especially, the isolate 150229 produced the highest level of Shiga toxin. Therefore, we identified the virulence genes (F18 and Stx2e) and demonstrated Shiga toxin-producing abilities from porcine edema disease causing E. coli filed isolates. These results suggested that one of the isolates could be a vaccine antigen candidate against STEC through further investigating to elicit an immune response.

• Journal of Microbiology and Biotechnology
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• v.21 no.9
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• pp.937-946
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• 2011

Several isolates of Bacillus thuringiensis (Bt) were screened for the vegetative insecticidal protein (Vip) effective against sap-sucking insect pests. Screening results were based on $LC_{50}$ values against cotton aphid (Aphis gossypii), one of the dangerous pests of various crop plants including cotton. Among the isolates, the Bt#BREF24 showed promising results, and upon purification the aphidicidal protein was recognized as a binary toxin. One of the components of this binary toxin was identified by peptide sequencing to be a homolog of Vip2A that has been reported previously in other Bacillus spp. Vip2 belongs to the binary toxin group Vip1-Vip2, and is responsible for the enzymatic activity; and Vip1 is the translocation and receptor binding protein. The two genes encoding the corresponding proteins of the binary toxin, designated as vip2Ae and vip1Ae, were cloned from the Bt#BREF24, sequenced, and heterologously expressed in Escherichia coli. Aphid feeding assay with the recombinant proteins confirmed that these proteins are indeed the two components of the binary toxins, and the presence of both partners is essential for the activity. Aphid specificity of the binary toxin was further verified by ligand blotting experiment, which identified an ~50 kDa receptor in the brush border membrane vesicles of the cotton aphids only, but not in the lepidopteran insects. Our finding holds a promise of its use in future as a candidate gene for developing transgenic crop plants tolerant against sap-sucking insect pests.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.309.2-309.2
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• 2002

The FimH subunit of type l-fimbriated Escherichia coli has been determined as a major cause of urinary tract infection. To produce a possible vaccine antigen against urinary tract infection, the fimH gene was genetically coupled to the ctxa2b gene, which was then cloned into pMAL -p2E expression vector. The chimaeric construction of pMALfimH/ctxa2b was transformed into Escherichia coli TB1 and its N-terminal amino acid sequence was analyzed. (omitted)