• Journal of Microbiology
• /
• v.44 no.3
• /
• pp.320-326
• /
• 2006

Pasteurella multocida is an important veterinary and opportunistic human pathogen. In particular, strains of P. multocida serogroup D cause progressive atrophic rhinitis, and produce a potent, intracellular, mitogenic toxin known as P. multocida toxin (PMT), which is encoded by the toxA gene. To further investigate the toxigenic and pathogenic effects of PMT, a toxA-deleted mutant was developed by homologous gene recombination. When administrated to mice, the toxigenicity of the toxA mutant P. multocida was drastically reduced, suggesting that the PMT constributes the major part of the toxigenicity of P, multocida. Similar results were obtained in a subsequent experiment, while high mortalities were observed when toxA(+) P. multocida bacterial culture or culture Iysate were administrated. Mice immunized with toxA(-) P. multocida were not protected (none survived) following challenge with toxA(+) P. multocida or bacterial culture Iysate (toxin). These results suggest that the toxigenicity of P. multocida is mainly derived from PMT.

• Korean Journal of Ecology and Environment
• /
• v.40 no.1
• /
• pp.149-154
• /
• 2007

In the present study, we performed the PCR assay using TOX2P/TOX2M primer targeting a specific region within mcyB gene to identify potential microcystin-producing cyanobacteria. TOX2P/TOX2M primer set was effective in amplifying mcy gene in the field samples containing Microcystis spp. of 1,000 cells per mL. Moreover, the results from the PCR assay agreed with those of the ELISA analysis. Consequently, this study demonstrated that TOX2P/TOX2M primer set can be used as a genetic probe for the early detection of cyanobacterial toxigenicity in Korean water bodies.

• Journal of Veterinary Clinics
• /
• v.26 no.5
• /
• pp.457-462
• /
• 2009

The present study was conducted to investigate the capsular serogroups and distribution of toxA gene of Pasteurella (P.) multocida isolated from pneumonic lung lesions of swine in Korea. A total number of 91 (36.3%) P. multocida isolated from 251 lung lesions. P. multocida isolates were typed for capsular serogroup and toxA gene by polymerase chain reaction. Of the 91 strains, serogroup A and D were 69 strains (75.8%) and 22 strains (24.2%), respectively. Sixty one strains (67.0%) out of 91 strains were detected as toxA gene, and 47 strains (77.0%) and 14 strains (23.0%) belongs to serogroup A and D, respectively.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.21 no.1
• /
• pp.127-132
• /
• 2010

We have characterized full-length cDNA encoding Gall-6-tox protein, which was cloned from the fat body of the immunized Galleria mellonella larvae. The cloned cDNA of Gall-6-tox consists of 1301 nucleotides and contained an open reading frame of 891 nucleotides corresponding to a protein of 296 residues that includes a putative 16-residue signal sequence and a 280-residue mature peptide with a calculated mass of 30,707.73 Da. The deduced mature peptide contains conserved tandem repeats of six cysteine-stabilized alpha beta ($Cs{\alpha}{\beta}$) motifs, which was detected in scorpion toxins and insect defensins. In the sequence homology search, mature Gall-6-tox showed 34% and 28% amino acid sequence homology with Bomb-6-tox from Bombyx mori and Spod-11-tox from Spodoptera frugiperda, respectively. Gall-6-tox orthologs were only found in Lepidopteran species, indicating that this new immune-related gene family is specific to this insect order. RT-PCR analysis revealed that Gall-6-tox was expressed primarily in the larval fat bodies, hemocytes, and midgut against invading bacteria into hemocoel. Moreover, the expression time course of Gall-6-tox was examined up to 24 h in the fat bodies and midgut after injection of E. coli. Altogether, these results suggest that Gall-6-tox is derived from defensins and Gall-6-tox may play a critical role in Lepidoptera immune system.

• Korean Journal of Veterinary Research
• /
• v.39 no.6
• /
• pp.1091-1098
• /
• 1999

Antimicrobial susceptibility, plasmid profiles and distribution of toxA gene were investigated in Pasteurella multocida isolated from pneumonic lung lesions of swine. The bacteria were highly susceptible to norfloxacin, cabenicillin, enrofloxacin and chloramphenicol, but resistant to colistin, sulfamethoxawle/trimethoprime, bacitracin, streptomycin. Sixty percentage of the isolates was resistant more than 2 drugs used in this experiment and 21 strains (23.6%) were resistant more than 5 drugs. This phenomenon meant that they had highly multi-drugs resistance. In the analysis of plasmid profiles, nineteen strains (47.5%) of 40 P multocida isolates harbored plasmids, ranging from 53.3kb to 2.49kb in size and the plasmid profiles could be classified into 5 groups. However, there was no relationship between the size and the profile of plasmid and the resistance pattern of antimicrobial agents. Thirty strains of 39 P multocida isolates (77%) investigated by PCR harbored toxA gene. This result suggested involvement of the ToxA protein expressed from the gene in pneumonic pasteurellosis of swine.

• Journal of Microbiology and Biotechnology
• /
• v.30 no.6
• /
• pp.830-838
• /
• 2020

The histone-like nucleoid structuring protein (H-NS) is an abundant global regulator of environmentally controlled gene expression. Herein, we demonstrate that H-NS represses the expression of LeuO, the master regulator of the cyclic(Phe-Pro)-dependent signaling pathway, by directly binding to the upstream region of the gene. H-NS binds to a long stretched region (more than 160-bp long), which overlaps with binding sites for ToxR and LeuO. A high quantity of H-NS outcompetes ToxR for binding to the cis-acting element of leuO. However, our footprinting analyses suggests that the binding of H-NS is relatively weaker than LeuO or ToxR at the same molarity. Considering that the DNA nucleotide sequences of the upstream regions of leuO genes are highly conserved among various Vibrio, such patterns as those found in V. vulnificus would be a common feature in the regulation of leuO gene expression in Vibrionaceae. Taken together, these results suggest that, in species belonging to Vibrionaceae, H-NS regulates the expression of leuO as a basal stopper when cFP-ToxR mediated signaling is absent.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.4 no.1
• /
• pp.43-49
• /
• 2002

We have cloned cDNAs encoding toxin from the spider, Araneus ventricosus, and constructed a recombinant baculovirus expressing the insecticidal toxin. The cDNAs encoding toxin were cloned from the cDNA library of A. ventricosus. Sequence analysis of the cDNAs encoding the toxin of A. ventricosus revealed that the 240 bp cDNA for AvTox-1 and 192 bp cDNA for AvTox-2 have an open reading frame of 80 and 64 amino acid residues, respectively. The deduced protein sequence of the toxin genes of AvTox-1 and AvTox-2 was aligned to that of the snack Anemonia sulcata and scorpion Centruroides limpidus limpidus, respectively. Northern blot analysis indicated that AvTox-2 toxin gene showed a fat body-spe-cific expression pattern at the transcriptional level. Furthermore, we have explored the possibility of improving baculovirus by incorporating the A. vontricosus toxin gene into Bombyx mori nuclear polyhedrosis virus genome under the control of polyhedrin promoter, The AvTox-2 toxin gene was expressed as approximately 5.8 kDa band in the recombinant baculovirus-injected silkworm larvae. Bioassays with the recombinant virus expressing AvTox-2 on 5th instar silkworm larvae demonstrated a decrease in the time to kill $(LT_{50} days)$ compared to wild-type BmNPV-Kl $(LT_{50} 6.72 days)$ in the injection of 10 viruses. These results indicate that A. ventricosus toxin is a novel member of the spider toxin family, suggesting that the toxin gene can be used in recombinant baculoviruses to reduce insect feeding damage and increase the speed of insect kill.

• The Plant Pathology Journal
• /
• v.34 no.2
• /
• pp.139-142
• /
• 2018

Pyrenophoratritici-repentis is the causal agent of tan spot. According to their ability to produce necrosis and/or chlorosis on a set of four differential bread wheats, the isolates of this fungus are currently grouped into eight races. When durum wheat genotypes were added to the differential set, a new virulence type was identified in Algeria. The isolates showing this virulence pattern are unable to attack bread wheat while they cause necrosis in durum genotypes. In this work, characterization of those isolates was based on pathological and molecular aspects. This included inoculation of bread and durum wheat, and virulence gene analysis using PCR and sequencing. The results showed that all isolates caused a resistance on all bread wheats of the differential set, while they produced necrosis in durum. ToxA and ToxB genes were amplified in all isolates, whereas toxb was absent. Sequence analysis for both genes showed no differences with those found in the two functional genes. The presence of two genes, ToxA and ToxB, despite the absence of symptoms usually caused by their products, suggests the existence of a new homologous for these two genes yet unknown. The presence of ToxA in the isolate unable to produce necrosis in Glenlea is reported for the first time.

• Korean Journal of Microbiology
• /
• v.39 no.3
• /
• pp.166-174
• /
• 2003

Microcystin produced by cyanobacteria in surface waters, such as eutrophic lake and river, is a kind of serious environmental problems due to its toxicity to human and wild animals. Microcystin is synthesized nonribosomally by the large modular multi-functional enzyme complex known as microcystin synthetase encoded by the mcy gene cluster. Amplification of mcy genes by PCR from cultures and environmental samples is a simple and efficient method to detect the toxigenic Microcystis. In order to evaluate primers designed to detect toxic microcystin-producing strains, 17 cyanobacterial strains and 20 environmental samples were examined by PCR with 7 pairs of primers. Some microcystin-producing cyanobacteria were not detected with FAA-RAA, TOX4F-TOX4R and FP-RP primers. The fragment of unexpected size was amplified with NSZW2-NSZW1 primers in Microcystis strains isolated from the lakes in Korea. TOX1P-TOX1F primers failed in amplification of toxin-producing strains. Only MSF-MSR and TOX2P- TOX2F primers amplified the fragments of mcy genes from 11 strains of microcystin-producing Microcystis. The water samples taken from 20 lakes in Korea were analyzed by PCR using each of the primers. In all the water samples, cyanobacteria capable of producing microcystin were detected by the PCR with TOX2P-TOX2F primers. These results indicate that TOX2P-TOX2F primers are better than the other primers for detection of microcystin-producing Microcystis strains in Korea. The nucleotide sequences of mcy gene in Microcystis aeruginosa NIER10010 suggest genetic diversity of Korean isolates.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.39 no.4
• /
• pp.595-601
• /
• 2010

This study was conducted to detect and identify Staphylococcus aureus, Vibrio parahaemolyticus, and Salmonella enterica subsp. using simultaneous multiplex polymerase chain reaction (multiplex PCR) assay. 23S rRNA partial gene (S. aureus), tox R gene (V. parahaemolyticus), and inv A gene (S. enterica subsp.) as diagnostic marker gene were suggested, and their amplicon sizes were 482 bp, 368 bp, and 284 bp, respectively. Non specific amplicons by STA-5F/STA-5R primer, ToxR-F/ToxR-R primer, and 139/141 primer were not observed in genomic DNA of pathogen bacteria as Bacillus cereus, Listeria monocytogenes, Escherichia coli, Proteus vulgaris, Streptococcus pyogenes, Candida albicans, and Shigella sonnei. The extracted crude DNA of targeted bacteria was detected as PCR template successfully. The detection limits were $10^5\sim10^4$ CFU/mL and 10 pg of purified genomic DNA of S. aureus, V. parahaemolyticus, and S. enterica subsp. by using simultaneous multiplex PCR.