• Microbiology and Biotechnology Letters
• /
• v.17 no.5
• /
• pp.447-453
• /
• 1989

In order to study the transfer of antibiotics resistance genes of the genetically cloned bacteria in water environments, DK1 strain, which is resistant to kanamycin (Km), chloramphenicol (Cm), streptomycin (Sm), and sulfadiazine (Su), was selected from the Gram-negative bacterial isolates from wastewater. One of 4 plasmids harboured in the DK1 strain was found to possess Km$^{${\gamma}$}$Cm$^{${\gamma}$}$ gene and be about 68 kb in size, and it was designated as pDK101. The plasmid of pDK101 was also found to have 16, 32, and 6 restriction sites for EcoRI. .PstI, and SalI, respectively. From the digestion fragments of pDK101 plasmid and pKT230 used as a vector by EcoRI restriction endonuclease, pDT309 and pDT529 were constructed as chimeric plasmids which possess Km$^{${\gamma}$}$Cm$^{${\gamma}$}$ gene and are 30.9 and 52.9 kb in size, respectively. When the chimeric plasmids were trasformed into E. coli C600 or E. coli HB101, transformants of DKC601, DKC602, DKH102, and DKH103 were obtained as cloned bacterial cells. The Km$^{${\gamma}$}$Cm$^{${\gamma}$}$ genes were well expressed in those cloned cells and the chimeric plasmids were clearly detected in the cloned cells of DKC601 and DKH103.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.5 no.2
• /
• pp.101-109
• /
• 2003

The study area, Kwangneung Experiment Forest (KEF) is located on the west-central portion of Korean peninsula and belongs to a cool-temperate broadleaved forest Bone. At the old-growth deciduous forest near Soribong-peak (533.1 m) in KEF, we have established a 1 ha permanent plot ($100m{\times}100m$) and a flux tower, and the site was registered as a KLTER(Korean long-term ecological research network) and DK site of KoFlux. In this site, we made a stemmap of trees and analyzed forest stand structure and physical and chemical soil characteristics, and estimated carbon budgets by forest components (tree biomass, soils, litter and so on). Dominant tree species were Quercus serrata and Carpinus laxiflora, and accompanied by Q. aliena, Carpinus cordata, and so on. As a result of a field survey of the plot, density of the trees larger than 2 cm in DBH was 1,473 trees per ha, total biomass 261.2 tons/ha, and basal area $28.0m^2$/ha. Parent rock type is granite gneiss. Soil type is brown forest soil (alfisols in USDA system), and the depth is from 38 to 66 cm. Soil texture is loam or sandy loam, and its pH was f개m 4.2 to 5.0 in the surface layer, and from 4.8 to 5.2 in the subsurface layer. Seasonal changes in LAI were measured by hemispherical photography at the 1.2 m height, and the maximum was 3.65. And the spatial distributions of volumetric soil moisture contents and LAIs of the plot were measured. The carbon pool in living tree biomass including below ground biomass was 136 tons C/ha, and 5.6 tons C/ha is stored in the litter layer, and about 92.0 tons C/ha in the soil to the 30 cm in depth. Totally more than about 233.6 tons C/ha was stored in DK site. These ground survey and monitoring data will give some important parameters and validation data for the forest dynamics models or biogeochemical dynamics models to predict or interpolate spatially the changes in forest ecosystem structure and function.

• Korean Journal of Veterinary Research
• /
• v.48 no.2
• /
• pp.153-159
• /
• 2008

Newcastle disease virus (NDV) is the causative agent of a highly contagious and devastating Newcastle disease of poultry. A NDV (isolate DK1/07) was isolated from apparently healthy wild spot-billed ducks (Anas poecilorhyncha) captured at upper branch of the SapGyo Creek in Chungbuk province, Korea during early 2007. The DK1/07 isolate of minimum chicken embryo lethal dose killed all SPF chicken embryos within 60 h. The cleavage site of the F protein possessed the amino acid sequence $^{112}R-R-Q-K-R-F^{117}$, which is a motif characteristic of virulent NDV strains. The F protein-based phylogenetic analysis revealed that the DK1/07 duck isolate was included in the cluster of genotype VIId and most closely related to recent NDV isolates obtained from chicken farms in Korea. Epidemiological importance of virulent NDV from wild duck is discussed.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.5 no.2
• /
• pp.87-93
• /
• 2003

Litterfall and litter decomposition represent a major contribution to the carbon and nutrient inputs in a forest ecosystem. We measured litterfall quantity and nutrient dynamics in decomposing litter for two years at the Kwangneung broadleaf natural forest (DK site) in Korea. Litterfall was collected in circular littertraps (collecting area : 0.25 $m^2$) and mass loss rates and nutrient release patterns in decomposing litter were estimated using the litterbag technique employing 30 cm ${\times}$ 30 cm nylon bags with 1.5 mm mesh size. Total annual litterfall was 5,627 kg/ha/yr and leaf litter accounted for 61 % of the litterfall. The leaf litter quantity was highest in Quercus serrata, fallowed by Carpinus laxiflora and C. cordata, etc., which are dominant tree species in the site. Mass loss from decomposing leaf litter was more rapid in C. laxiflora and C. cordata than in Q. serrata litter. About 77% of C. laxiflora and 84% of C. cordata litter disappeared, while about 48% in Q. serrata litter lost over two years. Lower mass loss rates of Q. serrata litter may be attributed to the difference of substrate quality such as lower nutrient concentrations compared with the other litter types. Nutrient concentrations (N, P, Mg) of three litter types except for potassium (K) increased compared with initial nutrient concentrations of litter over the study period. Compared with Q. serrata litter, nutrients (N, P, K, Ca, Mg) in C. laxiflora and C. cordata litter were released rapidly. The results suggest that litter mass loss and nutrient dynamic processes among tree species vary considerably in the same site conditions.

• Journal of the Korean Geosynthetics Society
• /
• v.19 no.4
• /
• pp.11-20
• /
• 2020

This study introduced the compact grouting method that can be used for improving soft ground and restoring buildings with unequal subsidence. The pump used in the traditional compact grouting method is a system that injects one hole each, which reduces the construction efficiency, and the analog injection method manually manages the construction by field workers, making it difficult to manage consistent quality. Pump and quality control system were developed to solve problems in existing construction. Since field supervisor determines amount of injected materials by using analog equipment and controls manually, it is difficult to manage consistent quality of construction. Therefore, the quality control system was developed in order to solve that problem. The quality control system consists of automatic mixing system of injection materials, multiple simultaneous injection pumps, and injection management monitoring system. Performance of the quality control system was verified through on-site testing, and ground improvement performance was verified through quality testing after testing and testing of the compact grouting method. Therefore, it is expected that the integrated quality control system developed will improve the quality assurance and efficiency and stability of construction at sites where construction and quality verification are difficult.

• Journal of the Korean Geosynthetics Society
• /
• v.18 no.4
• /
• pp.115-127
• /
• 2019

The low-flow grouting injection technique, the target construction method for this study, is a method of pouring mortar into the ground by non-emission replacement principle, which can be expected to increase the density of the ground, and, in some cases, be used as a base file using the strength of the high injection solids, along with low noise, low pollution, and high durability. To verify that the dynamic characteristics of the ground are improved by the low-flow injection technique, the test work was conducted on the site and physical tests were performed, and the quality of the improvement formed in the ground was verified through the indoor test on the core and core recovery rate was analyzed. The density logs test layer calculated the volume density of the ground layer by using the Compton scattering of gamma-rays, and the sonic logs was tested on the ground around the drill hole using a detector consisting of sonar and receiver devices inside the drill hole. As a result of the measurement of the change in physical properties (density and sonic logs) before and after grouting, both properties were basically increased after infusion of grout agent. However, the variation in density increase was greater than the increase in speed after grouting, and the ground density measurement method was thought to be effective in measuring the fill effect of the filler. Strength and core recovery rates were measured from specimens taken after the age of 28 days, and the results of the test results of the diffusion and strength test of the improved products were verified to satisfy the design criteria, thereby satisfying the seismic performance reinforcement.

• Molecules and Cells
• /
• v.46 no.12
• /
• pp.736-742
• /
• 2023

NifB, a radical S-adenosylmethionine (SAM) enzyme, is pivotal in the biosynthesis of the iron-molybdenum cofactor (FeMo-co), commonly referred to as the M-cluster. This cofactor, located within the active site of nitrogenase, is essential for the conversion of dinitrogen (N₂) to NH₃. Recognized as the most intricate metallocluster in nature, FeMo-co biosynthesis involves multiple proteins and a sequence of steps. Of particular significance, NifB directs the fusion of two [Fe₄S₄] clusters to assemble the 8Fe core, while also incorporating an interstitial carbide. Although NifB has been extensively studied, its molecular mechanisms remain elusive. In this review, we explore recent structural analyses of NifB and provide a comprehensive overview of the established catalytic mechanisms. We propose prospective directions for future research, emphasizing the relevance to biochemistry, agriculture, and environmental science. The goal of this review is to lay a solid foundation for future endeavors aimed at elucidating the atomic details of FeMo-co biosynthesis.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.22 no.1
• /
• pp.149-177
• /
• 1994

This study is practically focussed on the derivation of the formula of the reach of the catchment of urban community parks and the reached distance to the parks. The hypotheses for the formula are as follows. a. The catchment of urban community parks can be dependent on the quantitative characteristics that urban community parks have substanial factors : the potential residential population of the proximate community to a park, park visitor's day and mean usetime per year. b. The distance to the urban park is a decided variable which can be percieved quantitatively by the researchers among the exogenous variables concerned with the mean usetime of the urban community park. The data for the variables were collected from the statistics, and the surveys for 9 parks of 4cities(Seoul, Chong-ju, Su-Won, Chon-an) in Korea, which were divided into on-site samples and off-site ones in 1991. The data were collected by questionaire surveys. A total of 548 questionaires of off-site surveys were completed by the residents in the enticing area of the parks. A total of 1053 questionaires of on-site surveys were completed by the visitors of the parks. The research could attempt to derive a formula, which was concerned with the reach of the catchment of urban community parks and the reached distance to the parks. It is testified(R2>0.8) that the numbers of mean usetime per year should be related with the reached distance from a visitor's house to a proximate park. The formula is analogized with an exponential function: {{{{ Mean Usetime per year=f(x)=Ae-BK+Ce-DK ear, X is reached distance from a visitor's house to a proximate park. A,B,C and D are parameters. And, the differences of the reach of the catchment of the parks are not only testified with resulting from the differences of the exogenous variables of qualitative characteristics differences of the parks, but also divided separately into spatial ranges. This formula will be able to anticipate the visitor's numbers of a planned urban community park.

• The Korean Journal of Quaternary Research
• /
• v.17 no.2
• /
• pp.163-163
• /
• 2003

The study area, Kwangneung Experiment Forest (KEF) is located on the west-central portion of Korean peninsula and belongs to a cool-temperate broadleaved forest zone. At the old-growth deciduous forest near Soribong-peak (533.1m) in KEF, we have established a permanent plot and a flux tower, and the site was registered as a KLTER site and also a KoFlux site. In this study, we aimed to present basic ecological characteristics and synthetic data of carbon budgets and flows, and some monitoring data which are essential for providing important parameters and validation data for the forest dynamics models or biogeochemical dynamics models to predict or interpolate spatially the changes in forest ecosystem structure and function. We made a stemmap of trees in 1 ha plot and analyzed forest stand structure and physical and chemical soil characteristics, and estimated carbon budgets by forest components (tree biomass, soils, litter and so on). Dominant tree species were Quercus serrata and Carpinus laxiflora, and accompanied by Q. aliena, Carpinus cordata, and so on. As a result of a field survey of the plot, density of the trees larger than 2cm in DBH was 1,473 trees per ha, total biomass 261.2 tons/ha, and basal area 28.0 m2/ha. Parent rock type is granite gneiss. Soil type is brown forest soil (alfisols in USDA system), and the depth is from 38 to 66cm. Soil texture is loam or sandy loam, and its pH was from 4.2 to 5.0 in the surface layer, and from 4.8 to 5.2 in the subsurface layer. Seasonal changes in LAI were measured by hemispherical photography at the l.2m height, and the maximum was 3.65. And the spatial distributions of volumetric soil moisture contents and LAIs of the plot were measured. Litterfall was collected in circular littertraps (collecting area： 0.25m2) and mass loss rates and nutrient release patterns in decomposing litter were estimated using the litterbag technique employing 30cm30cm nylon bags with l.5mm mesh size. Total annual litterfall was 5,627 kg/ha/year and leaf litter accounted for 61% of the litterfall. The leaf litter quantity was highest in Quercus serrata, followed by Carpinus laxiflora and C. cordata, etc. Mass loss from decomposing leaf litter was more rapid in C. laxiflora and C. cordata than in Q. serrata litter. About 77% of C. laxiflora and 84% of C. cordata litter disappeared, while about 48% in Q. serrata litter lost over two years. The carbon pool in living tree biomass including below ground biomass was 136 tons C/ha, and 5.6 tons C/ha is stored in the litter layer, and about 92.0 tons C/ha in the soil to the 30cm in depth. Totally more than about 233.6 tons C/ha was stored in DK site. And then we have drawn a schematic diagram of carbon budgets and flows in each compartment of the KEF site.

• Journal of Life Science
• /
• v.13 no.2
• /
• pp.184-190
• /
• 2003

Myxococcus xanthus is a Gram negative, rod-shaped, soil bacterium that displays a social behaviors, and multicellular development upon nutrient deprivation. The csgA gene encoding a cell surface protein is essential for developmental behaviors including rippling, aggregation, fruiting body formation and sporulation. csgA mutants show normal vegetative growth, but lack all these developmental phenotypes. Expression of the CsgA (C-signal) specific genes are eliminated or dramatically reduced in csgA mutants. In order to identify components of C-signal transduction pathway, second site mutations were introduced into csgA mutants and were identified which can fully or partially restore development of csgA mutants (Rhie, H. G. et. al. 1989. J. Bacteriol. 171, 3268-3276). One of such csgA suppressor mutations, socD500 restores only sporulation to csgA mutants at 15$^{\circ}C$. The socD500 mutaion however eliminates the three basic developmental requirements, starvation, high cell density and a solid surface. Only sporulation, not accompanied with fruiting body formation is induced simply by shifting the temperature of vegetatively growing cells from $32^{\circ}C$ to $15^{\circ}C$. Spores induced by socD500 mutation is not as thick as that of wild-type fruiting body. In socD500 genetic background, two of ten C-signal dependent genes, $\Omega$DK4506 and $\Omega$DK4406 are more highly expressed in growing cells at $15^{\circ}C$. These results indicate that the socD500 mutation may be partly involved in the regulation of expression of two C-signal dependent genes and genes for sporulation in this transduction pathway.