• Toxicological Research
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• v.9 no.2
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• pp.187-194
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• 1993

[Met5]-Enkephalin (ME) secretion and the expression of proenkephalin A (proENK) mRNA were studied following long-term exposure of bovine adrenal medullary chromaffin (BAMC) cells to pertussis toxin. Prolonged (24 hr) stimulation of BAMC cells with pertussis toxin increased the secretion of ME as well as proENK gene expression. BAMC cells were also incubated with pertussis toxin in the presence or absence of other secretagogues such as nicotine, angiotensin II and phorbol myristate acetate.

• Development and Reproduction
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• v.16 no.3
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• pp.155-168
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• 2012

Therapeutic cancer is a long lasting and turbulent history accompany with the milestones in surgical intervention, chemotherapy and radiotherapy. In the past decade, however, metastatic cancer still obstinately exists challenging the professional scientist. Beside the major forms of cancer treatment, Diphtheria toxin (DT) which is produced by a pathogenic strain of bacterium Corynebacterium diphtheria to shield themselves against the other dangerous organism, have been researched as a potential candidate to overcome the drawback such as non-specific, non-effect to drug resistant cancer cell and side effects when using chemotherapy and radiotherapy. In the context of suicide gene therapy, the DT expression under controlling of tissue-specific promoter will be targeted in cancer cell but defect in normal cell. The molecular mechanism, characteristic of DT-bases therapy and prominent achievements of preclinical and clinical studies for the past decade are summarized and discussed in this review.

• Journal of Microbiology and Biotechnology
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• v.6 no.6
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• pp.451-455
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• 1996

Physiological studies on the expression of Bacillus thuringiensis subsp. tenebrionis (Btt) gene coding for insecticidal protein in recombinant Escherichia coli 537 were carried out to identify optimal culture condition. It was necessary to shift culture temperature from 30 to $42^{\circ}C$ to express the gene. Expression of the Btt toxin gene by recombinant E. coli 537 began within one hour after induction. Complex nitrogen sources increased production of the insecticidal protein. The total insecticidal protein was 0.5 g/I when using yeast extract as a complex nitrogen source. Soybean hydrolysate showed apparently the highest induction efficiency. After induction, the cellular content of the insecticidal protein was 5.4 times higher than it had been before induction. The optimal cultivation strategy was found to grow cells for 7hours at $30^{\circ}C$ and then 5-8 hours at $42^{\circ}C$. The optimal cultivation pH for the production of insecticidal protein was 6.5. The Btt toxin produced by the recombinant E. coli 537 was found to have the same level of potency against Colorado potato beetle as the original toxin.

• Microbiology and Biotechnology Letters
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• v.32 no.1
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• pp.11-15
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• 2004

Embryonic stem (ES) cells are derived from the inner cell mass of the blastocyst-stage embryos that can be propagated indefinitely and, at the same time, can be differentiated into all the cell types that constitute the body. Current research using ES cells is mainly focused on the efficient generation of specific cell types by employing optimal differentiation conditions, which often requires the genetic manipulation of ES cells. As a way of developing an efficient system to regulate foreign gene expression in ES cells, we have inserted the gene encoding Corynebacterium diphtheria toxin-A (DTA) into an autonomously induced plasmid under positive doxycycline control ('Tet-on' system). In this study, we demonstrate that this system can lead to the cell death of mouse ES cells by the induction of DTA expression when exposed to the tetracycline derivative, doxycycline. MTT assay showed that this induction resulted in the apoptosis of ES cells.

• Journal of Food Hygiene and Safety
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• v.35 no.1
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• pp.6-12
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• 2020

Prevalence of toxin genes and profiles of antibiotic resistance in Vibrio vulnificus were investigated for prevention of Vibrio sepsis and selection of effective antibiotics. A total of 23 V. vulnificus strains were isolated from Vibrio sepsis patients, fish, and water samples collected from fish tanks in restaurants in Jeonnam province during 2015-2017 period. Prevalence of toxin genes including, RtxA, viuB and vvhA were assessed and susceptibilities to 15 different antibiotics were determined. As a result of the toxin gene profile, the RtxA toxin gene was detected in 19 (82.6%) out of 23 strains, and vvhA and viuB toxin genes were positive in all strains. These results showed that V. vulnificus tested in this study possessed at least one more toxin gene, and the toxin gene detection rate was higher than in previous reports. Therefore, there is always a risk of Vibrio sepsis through eating fish or having contact with aquarium water at seafood restaurants. Especially, it was deemed necessary to provide preventive education about Vibrio sepsis for workers in such restaurants. The results of antibiotic susceptibility tests presented 94.4% resistance to cepoxitin antibiotics but all strains showed susceptibility to 14 kinds of antibiotics including chloramphenicol and tetracycline. The currents antibiotic therapy using chloramphenicol and teteracycline against Vibrio sepsis was judged to be useful.

• Korean Journal of Veterinary Research
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• v.41 no.2
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• pp.189-195
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• 2001

Single base substitution and deletion mutation have been introducted into the verotoxin 2 (VT2)A subunit gene from O157:H7 isolates to reduce cytotoxicity of VT2 and the cytotoxicity between wild type toxin and mutant toxoid were compared. A M13-derived recombinant plasmid pEP19RF containing a 940bp EcoRI-PstI fragment of VT2A gene was constructed for oligonucleotide-directed mutagenesis. The duoble mutant pDOEX was constructed by point and deletion mutation of two different highly conserved regions of VT2A encoding active site cleft of enzymatic domain. The key residue, Glu 167(GAA) and the pentamer(WGRIS) consisting of the enzymatic domain were replaced by ASP(GAC) and completely deleted in nucleotide sequence analysis of mutant, respectively. In the comparision of vero cell cytotoxicity between wide type toxin and toxoid from mutant, the wild type toxin expressed cytotoxicity in dilution of $10^{-6}$, but the toxid from mutant did not show cytotoxicity to vero cells.

• Korean Journal of Animal Reproduction
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• v.27 no.3
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• pp.225-231
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• 2003

Transgenic mice containing Diphtheria Toxin-A (DT-A) gene fused to proximal lck promoter sequences was used for analysis of DT-A gene expression and thymocyte development. The diphtheria toxin gene was expressed in thymus, spleen and liver of transgenic mice confirmed by RT-PCR and Northern blotting. A FACS analysis with thymocyte cell surface antigens antibodies (CD4 and CD8) showed that the number of peripheral mature single positive thymocytes ($CD4^{+}\;and\;CD8^{+}$ cells) T-cells was severely reduced in transgenic mice compared to that in the non-transgenic littermates. A relative portion of $CD8^{+}$ single positive thymocytes was about 33.2% in transgenic peripheral T-cells while 50.6% in wild type. Reduction of $CD4^{+}$ cell numbers in transgenic mice was observed (5.9% in transgenic versus 10.3% in non-transgenic). The data from analysis of these transgenic mice indicate that the proximal lck promoter regulated the expression of DT-A gene at high level in developing thymocytes and the DT-A disrupted developing thymocytes in transgenic mice.

• Journal of Environmental Health Sciences
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• v.38 no.6
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• pp.510-519
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• 2012

Objectives: This study was conducted in order to evaluate the microbiological contamination of the indoor air of the lunchrooms at child care centers and investigate the toxin genes and toxin production ability of food-borne pathogens. Methods: A total of 64 child care centers were sampled to test total aerobic bacteria, coliform bacteria, fungi, Staphylococcus aureus, Bacillus cereus and Salmonella spp. according to the Korea Food Code. All toxin genes of pathogens were detected using the Polymerase Chain Reaction method. The Sthaph. aureus enterotoxin was detected by a Staphylococcus aureus enterotoxin-reversed passive latex agglutination kit. The heamolysin BL (HBL) and non-heamolytic enterotoxin (NHE) produced by B. cereus were detected using a B. cereus enterotoxin-reversed passive latex agglutination kit and Bacillus diarrheal enterotoxin visual immunoassay kit, respectively. Results: The means of total aerobic bacteria and coliform bacteria were $1.91{\pm}1.84$ log CFU/plate and $0.47{\pm}0.62$ log CFU/plate, respectively. The mean of fungi also showed $0.59{\pm}0.71$ log CFU/plate. Among the pathogenic bacteria tested in this study, Staphy. aureus and B. cereus were detected in four (6.3%) and 21 (32.8%) out of 64 indoor air samples from lunchrooms in child care centers, respectively. All Staphy. aureus tested in this study possessed no toxin genes and did not produce enterotoxin. The detection rate of nheABC, hblCDA, entFM and ces toxin gene in B. cereus was 100, 57.1, 76.2 and 0%, respectively. B. cereus isolates were classified into four groups according to the presence or absence of toxin genes. The nheABC gene was the major toxin gene among B. cereus tested in this study. The HBL was detected in 11 out of 21 B. cereus isolates (52.4%) and three B. cereus isolates produced NHE (14.3%). Conclusion: The results indicated that the contamination by microorganisms in the indoor air of lunchrooms was unqualified to supply safe catering in child care centers. The ongoing control of indoor air quality is required.

• Korean Journal of Veterinary Research
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• v.44 no.4
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• pp.551-559
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• 2004

Shiga toxin-producing Escherichia coli (STEC) causes various clinical signs in human and animals, and has been indicated as a global enteropathogen with zoonotic importance. In this study, the feces of healthy pigs were collected from the slaughtered pigs of Daejon abattoir during the period from December 2001 to October 2002. Of 326 specimens, 13 STEC were confirmed by culture, PCR and colony hybridization. The isolates were further studied for toxin types, pathogenic factors, plasmid profiles, and antimicrobial resistance to characterize the genetic and toxigenic properties. In PCR, all of 13 isolates were evident to have shiga toxin gene (stx). Of 13 isolates stx1 gene was detected in 4 and stx2 gene in 9. The genes of eaeA, hlyA and rfbE were not present in any isolates. In colony hybridization using shiga toxin common primer (STXc), 2 to 9 per 100 colonies subcultured from 13 isolates showed the positive reaction. In the examination for plasmid profiles of the isolates, one to eleven plasmids with varying sizes of 1.0 Kb to 100 Kb were detected, and the 13 STEC could be classified into four groups by the plasmid patterns. The antimicrobial resistance patterns of the isolates were comparably corresponded with the plasmid profile patterns.

• The Plant Pathology Journal
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• v.33 no.6
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• pp.597-601
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• 2017

The clpks18 gene was first cloned and identified in Curvularia lunata. It contains 6571 base pairs (bp) and an 6276 bp open reading frame encoding 2091 amino acids. The ClPKS18 deletion mutant displayed an albino phenotype, and almost lost the ability to product 5-(hydroxymethyl) furan-2-carboxylate (M5HF2C) toxin, implying that clpks18 gene in C. lunata is not only involved in 1,8-dihydroxynaphthalene melanin synthesis, but also relatively associated with M5HF2C toxin biosynthesis of the pathogen. The pathogenicity assays revealed that ${\Delta}ClPKS18$ was impaired in colonizing the maize leaves, which corresponds to the finding that ClPKS18 controls the production of melanin and M5HF2C in C. lunata. Results indicate that ClPKS18 plays a vital role in regulating pathogenicity of in C. lunata.