• Microbiology and Biotechnology Letters
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• v.15 no.6
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• pp.396-401
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• 1987

Protein productivities of a cloned gene ($\beta$-galactosidase) and the cultural performances of two recombinant Escherichia coli strains, which use different host-vector systems, were studied. E. coli JM109/pTBG10 strain which carries Tac promoter had higher protein productivity than E. coli MH3000 (pRKc1857)/pASI(lacZ) strain which carries pL promoter. Induction of protein syn-thesis was optimum at the initial-and mid-logarithmic growth phases for both strains. Oxygen demand was observed to be very high during the cloned gene expression, and could be alleviated to some extent through pH control. The ratio of specific growth rates of plasmid-harboring to plasmidfree cell, $\mu$+ /$\mu$-, of the high productivity strain was observed to be lower than that of the low productivity one. Plasmid stability was analyzed for 20-30 generations, and it was found that the traction of plasmid-harboring cells dropped to l0% level in about 25 generations for both strains when the cloned gene expression was induced.

• Microbiology and Biotechnology Letters
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• v.17 no.3
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• pp.213-218
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• 1989

To investigate the possibility of using alkalophilic Bacillus sp. K-11 as a host for molecular cloning, plasmid pUB110 and pBD64 were introduced into alkalophilic Bacillus sp. K-17 by protoplast transformation system. Protoplasts of Bacillus sp. K-11 were prepared by treatment with 200 $\mu\textrm{g}$/$m\ell$ Iysozyme in SMM buffer containing 0.4M sucrose. Optimal temperature, pH and culture time for protoplast formation were 4$0^{\circ}C$, 7.0 and 4hrs, respectively. Cell wall was regenerated efficiently on DM3 medium containing 0.8% agar and 0.5M sodium succinate. Under these conditions for protoplast formation and regeneration, the highest transformation efficiency was obtained with cells incubated for 4hrs, and using 30%(V/V) of 40%(W/V) PEG6,000, In characteristics of transfer-mants, plasmid pUB110 was more stable than plasmid pBD64 in Bacillus sp. K-17. Maximum xylanase production of both transformants carrying pUB110 and pBD64, respectively was similar, but under the same conditions, enzyme secretion by transformant carrying pUB110 was earlier than that of transformant carrying pBD64.

• Journal of Microbiology and Biotechnology
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• v.12 no.4
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• pp.628-634
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• 2002

A microfilament-based motility in Toxoplasma gondii (T. gondii) Is involved in host cell invasion, yet the exact mechanism has not yet been determined. Accordingly, the current study examined the localization of actin and tubulin in T gondii using immunofluorescent (IF) and immunogold staining for electron microscopy. Indirect immunofluorescence (IF) staining using anti-actin and anti-tubulin monoclonal antibodies (mAbs) revealed localization of fluorescence on the entire surface of the tachyzoites. The actin in T. gondii was observed by immunogold staining, and the gold particles were seen on the surface, especially at the anterior end and in the cytoplasm of the parasite. However, there were no gold particles in the nucleus, rhoptries, and dense granules. The tubulin in T gondii was located on the surface and in the cytoplasm of the tachyzoites in the extracellular parasite, compared with anterior part of tachyzoites in the intracellular parasite. The antigens of T gondii recognized by anti-actin mAb were 107 kDa, 50 kDa, 48 kDa, and 40 kDa proteins, while those recognized by anti-tubulin mAb were 56 kDa, 52 kDa, and 34 kDa proteins. Tachyzoites of T gondii pretreated with the actin inhibitor, cytochalasin D (20 $\mu\textrm{g}$/ml), and tubulin inhibitor, colchicine (2$\times$10$\^$-6/ M), for 30 min at 37$\^{C}$ were used to infect the isolated mouse macrophages (tachyzo ites:macrophage=2:1). Pretreatment with the inhibitors resulted in lower multiplication of tachyzoites within the macrophages than in the untreated group 18 h post infection (p<0.05). Therefore, the present results suggest that actin and tubulin appear to be involved in the invasion of and multiplication in host cells.

• Korean journal of applied entomology
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• v.22 no.4 s.57
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• pp.293-299
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• 1983

Experiments were carried out to elucidate the specific interactions between host plant, Phaseolus vulgaris, and symbiotic bacteria, Rhizobium Phaseoli. Purified P. vulgaris lectins and six species of cultured Rhizobium were subjected to agglutination test. Lectins from bean and R. phaseoli showed relatively high agglutination activity indicating that host plant lectins recognize carbohydrate moieties on the compatible Rhizobium cell surface. The specific carbohydrate receptors for binding of the lectins on the cell surface of R. phaseoli were found as mannose and galactose. The minimum concentration of sugars for the inhibition was 6.25mM. The lectin content of cultured plant roots was measured after germination and was maximum in 5-day seedlings. The nodulation was competitively inhibited by lectins for the plants cultured with Rhizobium cells. By immunochemical studies, there was some relationship in antigenic determinants between R. phaseoli and R. japonicum but no relationships were observed with other Rhizobium species. The results suggest that the infection by rhizobia to the roots of leguminous plants may be caused by the specific interaction of lectins with rhizobia.

• IMMUNE NETWORK
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• v.11 no.6
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• pp.368-375
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• 2011

Background: Recent clinical observation reported that there was a significant correlation between change in circulating vascular endothelial growth factor (VEGF) levels and the occurrence of severe acute graft-versus-host disease (GVHD) following allogeneic hematopoietic stem cell transplantation (allo-HSCT), but the action mechanisms of VEGF in GVHD have not been demonstrated. Methods: This study investigated whether or not blockade of VEGF has an effect on acute GVHD in a lethally irradiated murine allo-HSCT model of $B6\;(H-2^b)\;{\rightarrow}B6D2F1\;(H-2^{b/d})$. Syngeneic or allogeneic recipient mice were injected subcutaneously with anti-VEGF peptides, dRK6 ($50{\mu}g/dose$) or control diluent every other day for 2 weeks (total 7 doses). Results: Administration of the dRK6 peptide after allo-HSCT significantly reduced survival with greaterclinical GVHD scores and body weight loss. Allogeneic recipients injected with the dRK6 peptide exhibited significantly increased circulating levels of VEGF and expansion of donor $CD3^+$ T cells on day +7 compared to control treated animals. The donor $CD4^+$ and $CD8^+$ T-cell subsets have differential expansion caused by the dRK6 injection. The circulating VEGF levels were reduced on day +14 regardless of blockade of VEGF. Conclusion: Together these findings demonstrate that the allo-reactive responses after allo-HSCT are exaggerated by the blockade of VEGF. VEGF seems to be consumed during the progression of acute GVHD in this murine allo-HSCT model.

• Molecules and Cells
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• v.21 no.1
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• pp.63-75
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• 2006

The 5′-region of Potato virus X (PVX) RNA, which contains an AC-rich, single-stranded region and stem-loop structure 1 (SL1), affects RNA replication and assembly. Using Systemic Evolution of Ligands by EXponential enrichment (SELEX) and the electrophoretic mobility shift assay, we demonstrate that SL1 interacts specifically with tobacco protoplast protein extracts (S100). The 36 nucleotides that correspond to the top region of SL1, which comprises stem C, loop C, stem D, and the tetra loop (TL), were randomized and bound to the S100. Remarkably, the wild-type (wt) sequence was selected in the second round, and the number of wt sequences increased as selection proceeded. All of the selected clones from the fifth round contained the wt sequence. Secondary structure predictions (mFOLD) of the recovered sequences revealed relatively stable stem-loop structures that resembled SL1, although the nucleotide sequences therein were different. Moreover, many of the clones selected in the fourth round conserved the TL and C-C mismatch, which suggests the importance of these elements in host protein binding. The SELEX clone that closely resembled the wt SL1 structure with the TL and C-C mismatch was able to replicate and cause systemic symptoms in plants, while most of the other winners replicated poorly only on inoculated leaves. The RNA replication level on protoplasts was also similarly affected. Taken together, these results indicate that the SL1 of PVX interacts with host protein(s) that play important roles related to virus replication.

• Proceedings of the Korean Society of Sericultural Science Conference
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• 1997.06a
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• pp.73-101
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• 1997

Baculoviruses are characterized by large double-stranded circular DNA genomes and rod-shaped enveloped virions. Bombyx mori nucleopolyhedrovirus(BmNPV) is a major pathogen, which causes severe damage in sericulture. Currently, BmNPV is recogtnized as an improtant tool in molecular biology, especially for expression of useful genes in B.mori cells and silkworm larvae. Our laboratories have focused on the studies of the molecular mechanisms of BmNPV replication and the application of BmNPV to agriculture and medicine. The entire nucleotide sequence of the BmNPV genome has recently determined. The BmNPV genome possessed 135 putative genes and 7 homologous repeated sequence (hrs) regions. Relatively little space, a few to a few hundred base-pairs, was observed between the open reading frames and hrs. Termination codons often overlapped. These results showed a compactly packde BmNPV genome. Based on comparative sequence analyses, we speculated that the ancestor of BmNPV was a baculovirus similar to Autographa californica NPV(AcNPV). The function of the BmNPV genes were characterized by gene deletion analysis; p35 was found to be involved in blocking apoptosis and cysteine proteinase was found to be involved in horizontal virus transmission by degrading viral-infected larval host. By AcNPV and BmNPV coinfection experiments, we identified a BmNPV gene involved in expanding host specificity of AcNPV. The identified gene was likely encoded a DNA helicase based on the amino acid sequence analysis; a few amino acid substitutions in the putative DNA helicase gene resulted in the expansion of host range of AcNPV. These findings indicate that BmNPV evolved within a short period from an AcNPV-like ancestral virus due to rapid evolution including specific amino acid substitutions and gene deletions/insertions.

• Ocean and Polar Research
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• v.43 no.4
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• pp.365-370
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• 2021

Manila clam Ruditapes philippinarum is present at high rates of density in tidal flats in Cheonsu Bay on the west coast of Korea, where clams often exhibit mass mortalities in late summer. We monitored the pathologic condition of clams at Hwangdo tidal flat (HD) to understand the parasitic impacts on clam fitness. Manila clams were fully ripe in July and spawned during August and September, as the histology indicated. The histology revealed that clams in HD tidal flats were heavily infected by the protozoa parasite Perkinsus olseni, as the monthly prevalence ranged from 53% (September) to 93% (August). In addition, Manila clams were co-infected by the metazoan parasite Cercaria tapetis and Parvatrema duboisi with the prevalence of 0-33% and 0-14%, respectively. Massive hemocyte infiltration and subsequent inflammation were commonly observed from the gills of P. olseni infected clams. Clusters of P. olseni trophozoites and heavy hemocyte infiltration were also observed from the female gonad, suggesting that P. olseni interferes with host gonad maturation. The larval trematode occupied almost the entire host gonad, resulting in gonad castration. In addition, Metacercaria of P. duboisi were observed from the subsurface of the mantle. Ray's fluid thioglycollate medium assay (RFTM) indicated that clams collected in August and September contained approximately 4.0×106 P. olseni cells/g gills. Condition Index (CI) declined gradually from spring to early summer, and the decline in CI was interpreted as a consequence of the heavy parasitism, as the parasites drain the host's net energy to be used in somatic growth and gamete production.

• Clinical and Experimental Pediatrics
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• v.65 no.4
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• pp.153-166
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• 2022

During the coronavirus disease 2019 (COVID-19) pandemic, a novel multisystem inflammatory syndrome in children (MIS-C) has been reported worldwide since the first cases were reported in Europe in April 2020. MIS-C is temporally associated with severe acute respiratory syndrome coronavirus 2 infection and shows Kawasaki disease (KD)-like features. The epidemiological and clinical characteristics in COVID-19, KD, and MIS-C differ, but severe cases of each disease share similar clinical and laboratory findings such as a protracted clinical course, multiorgan involvement, and similar activated biomarkers. These findings suggest that a common control system of the host may act against severe disease insult. To solve the enigmas, we proposed the protein-homeostasis-system hypothesis in that every disease involves etiological substances and the host's immune system controls them by their size and biochemical properties. Also, it is proposed that the etiological agents of KD and MIS-C might be certain strains in the microbiota of human species and etiological substances in severe COVID-19, KD, and MIS-C originate from pathogen-infected cells. Since disease severity depends on the amounts of inflammation-inducing substances and corresponding immune activation in the early stage of the disease, an early proper dose of corticosteroids and/or intravenous immunoglobulin (IVIG) may help reduce morbidity and possibly mortality among patients with these diseases. Corticosteroids are low cost and an analogue of host-origin cortisol among immune modulators. This study's findings will help clinicians treating severe COVID-19, KD, and MIS-C, especially in developing countries, where IVIG and biologics supplies are insufficient.

• IMMUNE NETWORK
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• v.23 no.4
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• pp.31.1-31.18
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• 2023

Evidence suggests that the human respiratory tract, as with the gastrointestinal tract, has evolved to its current state in association with commensal microbes. However, little is known about how the airway microbiome affects the development of airway immune system. Here, we uncover a previously unidentified mode of interaction between host airway immunity and a unique strain (AIT01) of Staphylococcus epidermidis, a predominant species of the nasal microbiome. Intranasal administration of AIT01 increased the population of neutrophils and monocytes in mouse lungs. The recruitment of these immune cells resulted in the protection of the murine host against infection by Pseudomonas aeruginosa, a pathogenic bacterium. Interestingly, an AIT01-secreted protein identified as GAPDH, a well-known bacterial moonlighting protein, mediated this protective effect. Intranasal delivery of the purified GAPDH conferred significant resistance against other Gram-negative pathogens (Klebsiella pneumoniae and Acinetobacter baumannii) and influenza A virus. Our findings demonstrate the potential of a native nasal microbe and its secretory protein to enhance innate immune defense against airway infections. These results offer a promising preventive measure, particularly relevant in the context of global pandemics.