• Proceedings of the Botanical Society of Korea Conference
• /
• 1985.08b
• /
• pp.59-71
• /
• 1985

In rice, limited efforts have been made to identify genes by the use of insertional mutagens, especially heterologous transposons such as the maize Ac/Ds. We constructed Ac and gene trap Ds vectors and introduced them into the rice genome by Agrobacterium-mediated transformation. In this report, rice plants that contained single and simple insertions of T-DNA were analyzed in order to evaluate the gene-tagging efficiency. The 3'end of Ds was examined for putative splicing donor sites. As observed in maize, three splice donor sites were identified at the 3'end of the Ds in rice. Nearly 80% of Ds elements wered excised from the original T-DNA sites, when Ac cDNA was expressed under a CaMV 35S promoter. Repetitive ratoon culturing was performed to induce new transpositions of Ds in new plants derived from cuttings. About 30% of the plants carried at least one Ds that underwent secondary transposition in the later cultures. 8% of transposed Ds elements expressed GUS in various tissues of rice panicles. With cloned DNA adjacent to Ds, the genomic complexities of the insertion sites were examined by Southern hybridization. Half of the Ds insertion sites showed simple hybriodization patterns which could be easily utilized to locate the Ds. Our data demonstrate that the Ac/Ds mediated gene trap system could prove an excellent tool for the analysis of functions of genes in rice. We discuss genetic strategies that could be employed in a largee scale mutagenesis using a heterologous Ac/Ds family in rice.

• Korean Journal of Microbiology
• /
• v.16 no.1
• /
• pp.30-40
• /
• 1978

Detergent soluble fractions were obtained from T. ferrooxidans ATCC 13598 and the T. thiooxidans ATCC 8085 which were treated with 3% of Tween 20. The detergent soluble antigen(crude antigen) fractions of the T.ferrooxidans and the T.thiooxidans were subjected to hydroxyapatite. In the case of T.thiooxidans, further purification was carried out on the DEAE-cellulose column chromatography. The antigen fractions, such as the hydroxyapatite peak-1(Tf, HA-1) and peak-2 from T.ferrooxidans(Tf. HA-2) and hydroxyapatite peak-1(Tt, HA-1), DEAE-cellulose peak-1(Tt, DP-1) and peak-2(Tt, DP-2) from T. thiooxidans wre compared each other with the homologous and the heterologous and the heterologous antisera against to the Thiobacillus species. The hydroxyapatite peak-2 fraction from the T.ferrooxidans(Tf, HA-2) and DEAE-cellulose peak-2 fraction from the T.thiooxidans(Tt, DP-2) were represented the type-specific immuno-reactivities between the T.ferrooxidans and the T.thiooxidans on the several sets of double gel diffusioin analysis. The type-specific antigen fractions from both of the baceteria were mainly composed of protein with entierly different electrophoretic mobility on the SDS-polyacrylamide gel electrophoresis. However, the PAS positive banding patterns on the electrophorogram showed wide range of common antigenic properties in the T. ferrooxidans and the T.thiooxidans, respectively.

• The Korean Journal of Physiology and Pharmacology
• /
• v.5 no.6
• /
• pp.511-519
• /
• 2001

Nimopidine, one of dihydropyridine derivatives, has been widely used to pharmacologically identify L-type Ca currents. In this study, it was tested if nimodipine is a selective blocker for L-type Ca currents in sensory neurons and heterologous system. In mouse dorsal root ganglion neurons (DRG), low concentrations of nimodipine $(<10\;{\mu}M),$ mainly targeting L-type Ca currents, blocked high-voltage-activated calcium channel currents by ${\sim}38%.$ Interestingly, high concentrations of nimodipine $(>10\;{\mu}M)$ further reduced the 'residual' currents in DRG neurons from ${\alpha}_{1E}$ knock-out mice, after blocking L-, N- and P/Q-type Ca currents with $10\;{\mu}M$ nimodipine, $1\;{\mu}M\;{\omega}-conotoxin$ GVIA and 200 nM ${\omega-agatoxin$ IVA, indicating inhibitory effects of nimodipine on R-type Ca currents. Nimodipine $(>10\;{\mu}M)$ also produced the inhibition of both low-voltage-activated calcium channel currents in DRG neurons and ${\alpha}_{1B}\;and\;{\alpha}_{1E}$ subunit based Ca channel currents in heterologous system. These results suggest that higher nimodipine $(>10\;{\mu}M)$ is not necessarily selective for L-type Ca currents. While care should be taken in using nimodipine for pharmacologically defining L-type Ca currents from native macroscopic Ca currents, nimodipine $(>10\;{\mu}M)$ could be a useful pharmacological tool for characterizing R-type Ca currents when combined with toxins blocking other types of Ca channels.

• Journal of Microbiology and Biotechnology
• /
• v.23 no.2
• /
• pp.149-155
• /
• 2013

Heterologous expression of a putative $K^+/H^+$ antiporter of Streptomyces coelicolor A3(2) (designated as sha4) in E. coli and Streptomyces hygroscopicus JCM4427 showed enhanced tolerance to $K^+$ stress, acidic-pH shock, and/or geldanamycin production under $K^+$ stress. In a series of $K^+$ extrusion experiments with sha4-carrying E. coli deficient in the $K^+/H^+$ antiporter, a restoration of impaired $K^+$ extrusion activity was observed. Based on this, it was concluded that sha4 was a true $K^+/H^+$ antiporter. In different sets of experiments, the sha4-carrying E. coli showed significantly improved tolerances to $K^+$ stresses and acidic-pH shock, whereas sha4-carrying S. hygroscopicus showed an improvement in $K^+$ stress tolerance only. The sha4-carrying S. hygroscopicus showed much higher geldanamycin productivity than the control under $K^+$ stress condition. In another set of experiments with a production medium, the secretion of geldanamycin was also significantly enhanced by the expression of sha4.

• Animal cells and systems
• /
• v.6 no.4
• /
• pp.305-309
• /
• 2002

Actinorhodin antibiotics produced by Streptomyces lividans TK24 are blue pigments with a weak antibiotic activity, derived from one acetyl-CoA and 15 malonyl-CoA units via a typical ployketide pathway. In an attempt to clone polyketide biosynthetic genes of S. lividans TK24, hybridizing fragments in the genomic DNA of S. lividans TK24 were detected by use of acn and act III polyketide synthase gene probes. Since typical aromatic polyketide bio-synthetic gene clusters are roughly 22-34 Kb long, we constructed in E. coli XL-Blue MR using the Streptomyces-E. coli bifunctional shuttle cosmid vector (pojn46). Then, about 5,000 individual E. coii colonies were thor-oughly screened with acrl-ORFI and actIII probes. From these cosmid libra-ries, 12 positive clones were identified. Restriction analysis and southern hybridization showed two polyketide biosynthetic gene clusters in this organism. These cosmid clones can be transformed into Streptomyces parvulus 12434 for expression test that identify product of actinorhodin biosynthetic genes by heterologous expression. Thus, heterologous expres-sion of a derivative compound of a actinorhodin biosynthetic intermediate was obtained in pKE2430. Expression of these compounds by the trans-formants was detected by photodiode array HPLC analysis of crude extracts.

• Molecules and Cells
• /
• v.38 no.12
• /
• pp.1105-1110
• /
• 2015

Phleichrome, a pigment produced by the phytopathogenic fungus Cladosporium phlei, is a fungal perylenequinone whose photodynamic activity has been studied intensively. To determine the biological function of phleichrome and to engineer a strain with enhanced production of phleichrome, we identified the gene responsible for the synthesis of phleichrome. Structural comparison of phleichrome with other fungal perylenequinones suggested that phleichrome is synthesized via polyketide pathway. We recently identified four different polyketide synthase (PKS) genes encompassing three major clades of fungal PKSs that differ with respect to reducing conditions for the polyketide product. Based on in silico analysis of cloned genes, we hypothesized that the non-reducing PKS gene, Cppks1, is involved in phleichrome biosynthesis. Increased accumulation of Cppks1 transcript was observed in response to supplementation with the application of synthetic inducer cyclo-(${_L}-Pro-{_L}-Phe$). In addition, heterologous expression of the Cppks1 gene in Cryphonectria parasitica resulted in the production of phleichrome. These results provide convincing evidence that the Cppks1 gene is responsible for the biosynthesis of phleichrome.

• Preventive Nutrition and Food Science
• /
• v.15 no.4
• /
• pp.360-363
• /
• 2010

To enhance the expression and secretion of pediocin PA-1 from heterologous bacterial hosts, the promoter and deduced signal sequence (PS) of an $\alpha$-amylase gene from a Bifidobacterium adolescentis strain was fused with pediocin PA-1 structural and immunity genes (AB) and the resulting functions were evaluated in Escherichia coli. Two recombinant PCR products were created-one with just the deduced signal sequence and one with the sequence plus the Ser and Thr sequences that are the next two amino acids of the signal sequence. These two products, the PSAB (---AQA::KYY---) and PSABST (---AQA$\underline{ST}$::KYY---), respectively, were inserted into a TA cloning vector (yT&A) and named pPSAB, which was previously reported, and pPSABST. The two recombinant plasmid DNAs were transferred into E. coli JM109 and the transformants displayed antimicrobial activity, where the activity of E. coli JM109 (pPSAB) was stronger than that of E. coli JM109 (pPSABST), indicating that the ST amino acid residues were not necessary for secretion and might have even decreased the antimicrobial activity of recombinant pediocin PA-1.

• Biomolecules & Therapeutics
• /
• v.6 no.2
• /
• pp.191-198
• /
• 1998

Vsrio vulnificus is an estuarine gram-negative human pathogen that affects people with chronic hepatitis, alcoholic cirrhosis, diabetes mellitus or other underlying diseases. V. vulnificus infection is mediated primarily by consumption of raw fish or by exposure of pre-existing wounds to seawater, causing permanent tissue damages or fatal septic shock. We have been developing a vaccine against V. vulnificus composed of whole cell Iysate of a V. vulnificus O-antigen serotype 4 strain. Oral administration of the V. vulnificus;oral vaccine;immunogenicity;protective efficacy vaccine elicited a high serum antibody response in rabbits. The induced antibodies were reactive not only to the homologous strain but also to heterologous O-antigen serotype strains, indicating cross-reactivities among serotypes. Western blot analysis revealed that the antibodies are mainly specific for outer membrane proteins (OMPs) and reacted equally well with OMPs purified from 9 O-antigen serotypes. The rabbit antisera showed opsonophagocytic killing activity against heterologous strains as well as the homologous strain. Passively transferred rabbit antisera into mice were protective against a lethal V. vulnificus infection. These data demonstrate that oral administration of the V. vulnificus vaccine induced a systemic antibody response which had a protective efficacy against V. vulnificus infections, suggesting that this vaccine preparation could be used to develop an oral vaccine against V. vulnificus.

• Journal of Microbiology and Biotechnology
• /
• v.29 no.5
• /
• pp.667-686
• /
• 2019

Streptomyces are attractive microbial cell factories that have industrial capability to produce a wide array of bioactive secondary metabolites. However, the genetic potential of the Streptomyces species has not been fully utilized because most of their secondary metabolite biosynthetic gene clusters (SM-BGCs) are silent under laboratory culture conditions. In an effort to activate SM-BGCs encoded in Streptomyces genomes, synthetic biology has emerged as a robust strategy to understand, design, and engineer the biosynthetic capability of Streptomyces secondary metabolites. In this regard, diverse synthetic biology tools have been developed for Streptomyces species with technical advances in DNA synthesis, sequencing, and editing. Here, we review recent progress in the development of synthetic biology tools for the production of novel secondary metabolites in Streptomyces, including genomic elements and genome engineering tools for Streptomyces, the heterologous gene expression strategy of designed biosynthetic gene clusters in the Streptomyces chassis strain, and future directions to expand diversity of novel secondary metabolites.

• Korean Journal of Veterinary Research
• /
• v.29 no.3
• /
• pp.283-289
• /
• 1989

In order to measure in vitro cell mediated immunity in the guinea pigs sensitized with the killed bacilli of Mycobacterium bovis ($AN_5$), M avium (serotype 2), M tuberculosis and M intracellulare (serotype 8), leukocyte adherence inhibition (LAI) test was established using the antigens of purified protein derivatives (PPD) tuberculin. By using LAI test, specificity of cell-mediated immune responses of the guinea pigs inoculated with various Mycobacterium spp was investigated, and comparison between values of LAI and skin test was also made to evaluate the specificity of the newly designed test. The results obtained throughout the experiments were summarized as follows; 1. The optimal concentration of PPD antigens for LAI test was 1 to 2mg per ml of medium. 2. When the leukocytes of guinea pigs sensitized with both M bovis($AN_5$) and M avium (serotype 2) for 2 to 8 weeks were incubated with homologous or heterologous PPD antigens, mean values of LAI test were $61.2{\pm}11.2$ and $65.6{\pm}5.1%$ in homologous PPD antigens respectively, while $30.0{\pm}3.7$ and $32.8{\pm}5.7%$ in heteNlogous PPD antigens, showing the prominently high value of LAI in the homologous syst,em (p<0.01). 3. When the leukocytes of guinea pigs sensitized with both M tuberculosis and M intracellulare (serotype 8) for 2 to 8 weeks were incubated with homologous and heterologous PPD antigens, mean values of LAI test were $67.9{\pm}2.9$ and $66.9{\pm}5.0%$ in homologous PPD antigens, while $27.4{\pm}7.4$ and $24.4{\pm}7.1%$ in heterologous PPD antigens, showing the prominently high value of LAI in the homologous system (p<0.01). 4. Comparing with the specificity of LAI and skin tests on the basis of the value obtained from the homologous system, deviation of reaction was revealed to be 49.5 to 100.2 in LAI test, and -15.9 to 52.0 in skin test.