• Korean Journal of Food Science and Technology
• /
• v.52 no.1
• /
• pp.103-108
• /
• 2020

Shiga toxin-producing Escherichia coli (STEC) is an important pathogenic bacteria and can cause severe foodborne disease. For STEC detection, conventional culture methods have disadvantages in the fact that conventional culture takes a long time to detect and PCR can also detect dead bacteria. To overcome these problems, we suggest a bacteriophage amplification assay, which utilizes the ability of bacteriophages to infect living cells and their high specificity. We used a combination of six bacteriophages infecting E. coli to make the bacteriophage cocktail and added ferrous ammonium sulfate as a virucidal agent to remove free-bacteriophages. When cherry tomato and paprika were artificially inoculated with the cocktail at a final concentration of around 3 log CFU/mL and were enriched for at least 5 h in mTSB broth with Novobiocin, approximately 2-3 log PFU/mL were detected through the bacteriophage amplification assay. Therefore, bacteriophage amplification assay might be convenient and a useful method to detect STEC in a short period of time.

• BMB Reports
• /
• v.46 no.2
• /
• pp.124-129
• /
• 2013

FK506 binding protein 12 (FK506BP) belongs to a family of immunophilins, and is involved in multiple biological processes. However, the function of FK506BP in corneal disease remains unclear. In this study, we examined the protective effects on dry eye disease in a Botulinum toxin A (BTX-A) induced mouse model, using a cell-permeable PEP-1-FK506BP protein. PEP-1-FK506BP efficiently transduced into human corneal epithelial cells in a time- and dose-dependent manner, and remained stable in the cells for 48 h. In addition, we demonstrated that topical application of PEP-1-FK506BP was transduced into mouse cornea and conjunctiva by immunohistochemistry. Furthermore, topical application of PEP-1-FK506BP to BTX-A-induced mouse model markedly inhibited expression levels of pro-inflammatory cytokines such as interleukin-$1{\beta}$ (IL-$1{\beta}$), tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$) and macrophage inhibitory factor (MIF) in corneal and conjunctival epithelium. These results suggest PEP-1-FK506BP as a potential therapeutic agent for dry eye diseases.

• Microbiology and Biotechnology Letters
• /
• v.27 no.5
• /
• pp.419-425
• /
• 1999

Prophylactic effects of Bifidobacterium longum HY8001, Korean isolate, against Escherichia coli O157:H7 and Salmonella typhimurium DT104 enteric infection were examined at four groups of specific pathogen free(SPF)-ICR mouse for each pathogen. B. longum HY8001+B. typhimurium DT104+B. longum HY8001(BL+ST+BL) group and B. longum HY8001+E. coli O157:H7+B. longum HY8001(BL+E+BL) group were fed with B. longum HY8001 before and after E. coli O157:H7 or s. typhimurium DT104 challenge, while B. longum HY8001+S. typhimurium DT104(BL+ST) and B. longum HY8001+e. coli O157:H7(BL+E) groups were fed with B. longum HY8001 only before E. coli O157:H7 or S. typhimurium DT104 challenge. E. coli O157:H7(E) and S. typhimurium DT104(ST) groups were challenged with each pathogen without B. longum HY8001 administration and control groups were administered with phosphate buffered solution(PBS). After the oral administration with B. longum HY8001(109cfu), th emice were challenged with E. coli O157:H7(2$\times$1010cfu) or S. typhimurium DT104(108cfu) and the mortality rate and the fecal shedding of challenged pathogen were also examined define the reactivity of the B. longum HY8001. Production of toxin neutralizing substance(s) of B. longum HY8001 was determined by cell cytotoxicity assay using Vero cells. Fecal shedding of th eS. typhimurium DT104 was significantly decreased in BL+ST+BL group fed with B. longum HY8--1 before and after challenge(p<0.05), while the fecal shedding s of S. typhimurium DT104 in BL+ST and St groups remained more than 106cfu. the protective effect of the B. longum HY8001 against E. coli O157:H7 was significantly high only in BL+E+BL group fed with b. longum Hy8001 before and after E. coli O157:H7 challenge from the result of fecal E. coli O157:H7 isolation rate, mortality rate, and intestinal contents culture to detect E. coli O157:H7. the mortality rate of the BL+e and E groups. The cytopathic effect (CPE) of the Vero cytotoxin (Shiga like toxin I & II) in Vero cell was neutralized in B. longum HY8001 culture supernatant added wells which indicate the presence of soluble Vero cytotxin neutralizing substance(s) in B. longum HY8001 culture suprnatant.

• Journal of Food Hygiene and Safety
• /
• v.32 no.1
• /
• pp.50-56
• /
• 2017

The purpose of this study was to investigate the microbiological contamination of water and drinking cups in springs and to estimate the toxin gene, enterotoxin production ability and antibiotic susceptibility of foodborne pathogens. Ten spring water and 34 drinking cups were tested. The average number of total aerobic bacteria and coliform bacteria in spring water were 1.8 log CFU/mL and 1.2 log CFU/mL, and in drinking cups were $4.7log\;CFU/100cm^2$ and $1.7log\;CFU/100cm^2$. Salmonella spp., Staphylococcus aureus, E. coli O157:H7, Listeria monocytogenes, Vibrio parahaemolyticus, Yersinia enterocolitica were not isolated from all of samples but Bacillus cereus was detected in 5 (14.7%) of 34 drinking cups. The nheA and entFM genes were major enterotoxin genes in B. cereus isolated from drinking cups. All of B. cereus tested in this study produce non-heamolytic enterotoxin but only 2 isolates possessed heamolysin BL enterotoxin producing ability. B. cereus was resistant to ${\beta}-lactam$ antibiotics. These results revealed that the sanitary conditions of drinking cups in spring should be improved promptly. The substitution carrying a personal drinking cup for the public drinking cups equipped in springs is suggested to prevent food-borne illness.

• Korean journal of applied entomology
• /
• v.61 no.1
• /
• pp.117-128
• /
• 2022

In this study, we have examined pyrethroid actions on sodium channels in the pest insect Heliothis virescens. The synthetic pyrethroid permethrin increased steady-state sodium current in H. virescens central neurons and prolonged tail currents (I_Na-tail) due to extreme slowing of sodium channel deactivation. Prolongation of I_Na-tail was evident at permethrin concentrations as low as 60 nM, which modified ~1.7% of sodium channels and 10 μM permethrin modified about 30% of channels. The average time constant (τ₁) of tail current decay was ~335 ms for permethrin-modified channels. These modified channels activated at more negative potentials and showed slower activation kinetics, and failed to inactivate. Permethrin modification of sodium channels was dramatically potentiated by the α scorpion toxin LqhαIT, showing positive cooperativity between two binding sites. The amplitude of the tail current induced by 0.3 μM permethrin was enhanced ~8-fold by LqhαIT (200 pM). Positive cooperativity was also observed between permethrin and the insect-specific scorpion toxin AaIT as 10 nM permethrin potentiated the shift of voltage dependence caused by AaIT (~2-fold).

• Proceedings of the Korean Society of Embryo Transfer Conference
• /
• 2002.11a
• /
• pp.96-96
• /
• 2002

We examined the role of SR 144528 (N-[-(1S-endo-1,3,,3-trimethyl-bicycle[2, 2, 1 ] heptan-2-y1]-5-(-4-chloro-3-mothyl-phenyl)-(4-methylbenzyl)-pyrazole-3- carboxamide) in the modulation of certain AC isoforms in transiently transfected COS-7 cells. We found that CB2 in COS cells has a constitutive activity, and thus leading to inhibition of AC-V activity even in the absence of agonist. In addition, this constitutive modulation of AC is reversed by SR144528. It is now well established that several G protein-coupled receptors can signal without agonist stimulation(constitutive receptors). Inverse agonists have been shown to inhibit the activity of such constitutive G protein-coupled receptor signaling. Agonist activation of the G$\_$i/o/-coupled peripheral cannabinoid receptor CB2 normally inhibits adenylyl cyclase type V and stimulates adenylyl cyclase type II. Using transfected COS cells, we show here that application of SR144528, an inverse agonist of CB2, leads to a reverse action (stimulation of adenylyl cyclase V and inhibition of adenylyl cyclase II). This inverse agonism of SR144528 is dependent on the temperature, as well as on the concentration of the cDNA of CB2 transfected. Pertussis toxin blocked the regulation of adenylyl cyclase activity by SR 144528.

• The Journal of the Korean Society for Microbiology
• /
• v.20 no.1
• /
• pp.55-63
• /
• 1985

Phosphate, ammonia, glucosamine, glucose, pyruvate, succinate, fumarate, malate and acetate were examined for their ability to control the heat-stable enterotoxin (ST) production in succinate salts medium or in M9 medium. The results obtained were summerized as follows. 1. When the initial phosphate concentration was adjusted to 1.0mM, ST production was decreased to 80u/ml or less. But when the initial phosphate concentration was adjusted to 64mM or 100mM, enterotoxin production was 320u/ml. 2. When the initial ammonia concentration in the medium was adjusted to 1.0mM, no ST production and cell growth were observed. But when ammonia concentration was adjusted to 10mM, 19mM, 38mM or 76mM, enterotoxin production was 320u/ml. 3. Among carbon sources, glucosamine, glucose, pyruvate, succinate, fumarate, malate and acetate, acetate supported the highest specific production (928 unit/O.D.) of heat-stable enterotoxin. From this results, we could assume that heat-stable enterotoxin production is controlled by stringent control mechanism. 4. When the pH of the succinate salts medium was kept between 6.2 to 6.5, no heat-stable enterotoxin production was observed, but when the pH of the medium was kept between pH 6.2 to 6.5, 267 unit/O.D. of heat-stable enterotoxin was produced. 5. Glucose inhibited the heat-stable enterotoxin production and the mechanism was assumed due to its capacity to lower the pH of the medium during catabolysis and its high metabolic energy.

• Asian-Australasian Journal of Animal Sciences
• /
• v.16 no.11
• /
• pp.1686-1689
• /
• 2003

The ability of ten probiotic bacteria to bind a common food carcinogen aflatoxin $G_1$,$G_2$ and $B_2$ was assessed. The strains were incubated in vitro with aflatoxins and the toxin residues in the supernatant were measured using high performance liquid chromatography. The aflatoxin $G_1$ binding capacity of the strains was found to strain dependent, most efficient binding of AF$G_1$ was observed by L. acidophilus CU028 and L. brevis CU06 which bound approximately 50%. L. acidophilus CU028 was capable of bind approximately 67% of AF$G_2$, difference in their binding ability showed statistical significance (p>0.05). L. acidophilus CU028 and L. helveticus CU 631 were the best binders and the strains were observed to possess variable AF$B_2$-binding ability in the range was from 38.0% to 55.9%. Lactobacillus acidophilus CU028 was the best common binders of the three types of food carcinogen aflatoxins. The application of binding phenomenon in the removal of mycotoxins from contaminated feeds is urgently needed to improve the safety of feeds.

• The Plant Pathology Journal
• /
• v.31 no.2
• /
• pp.108-114
• /
• 2015

Curvularia lunata is an important maize foliar fungal pathogen that distributes widely in maize growing area in China, and several key pathogenic factors have been isolated. An yeast two-hybrid (Y2H) library is a very useful platform to further unravel novel pathogenic factors in C. lunata. To construct a high-quality full length-expression cDNA library from the C. lunata for application to pathogenesis-related protein-protein interaction screening, total RNA was extracted. The SMART (Switching Mechanism At 5' end of the RNA Transcript) technique was used for cDNA synthesis. Double-stranded cDNA was ligated into the pGADT7-Rec vector with Herring Testes Carrier DNA using homologous recombination method. The ligation mixture was transformed into competent yeast AH109 cells to construct the primary cDNA library. Eventually, a high qualitative library was successfully established according to an evaluation on quality. The transformation efficiency was about $6.39{\times}10^5$ transformants/$3{\mu}g$ pGADT7-Rec. The titer of the primary cDNA library was $2.5{\times}10^8cfu/mL$. The numbers for the cDNA library was $2.46{\times}10^5$. Randomly picked clones show that the recombination rate was 88.24%. Gel electrophoresis results indicated that the fragments ranged from 0.4 kb to 3.0 kb. Melanin synthesis protein Brn1 (1,3,8-hydroxynaphthalene reductase) was used as a "bait" to test the sufficiency of the Y2H library. As a result, a cDNA clone encoding VelB protein that was known to be involved in the regulation of diverse cellular processes, including control of secondary metabolism containing melanin and toxin production in many filamentous fungi was identified. Further study on the exact role of the VelB gene is underway.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.21 no.3
• /
• pp.161-168
• /
• 1988

The Stability of PSP extracted from the intoxicated sea mussel, Mytilus edulis was evaluated by the thange of heating conditions and pH of the PSP solution. Also the composition of the PSP extracted from the cultured sea mussel collected at Chungmu, Korea on March 12, 1986 was analyzed. The extracted PSP was stable over the range of pH 2.0 to 4.0, but it was unstable above pH 4.5. For example. the toxicity of extracted PSP of pH 3.0 was only decreased less than $20\%$ by the treatment at $121^{\circ}C$ for 15min or at 100 for 2 hours, but it was decreased more than $80\%$ by the same treatment when the pH of the PSP solution was adjusted to 6.0. The toxin was purified from the ethanolic extract of the digestive glands of the sampled sea mussel by Bio-gel P-2 and Bio-Rex 70 column chromatography. The toxic fractions obtained were analyzed by cellulose acetate membrane electrophoresis, TLC and HPLC. The compositional analytical results of the PSP, most of the toxins were certified as $GTX_{1-4}$, while the toxicity of STX was only about 1/40 of that of $GTX_s$.