• Economic and Environmental Geology
• /
• v.48 no.3
• /
• pp.261-271
• /
• 2015

Toxicity results of metals, nanoparticles (NPs), and soils contaminated with metals were introduced on this review. Following methods were used: seed germination, bioluminescence, enzyme activity, and mutation. In general, different sensitivities were observed, depending on types of bioassays and pollutants. Among tested seeds, sensitivities of Lactucus and Raphanus were greater than others. Of single metal exposure, effect by As(III) was greater than others, and high revertant mutation ratio (5.1) was observed at 1 mg/L arsenite, indicating high mutagenicity. No general pattern was observed on the effect of metal mixture, but synergistic effect was observed with seeds. In case of soils, no correlation was observed between total metal contents and toxicity. Toxicity of NPs was observed as follows: CuO > ZnO > NiO > $TiO_2$, $Fe_2O_3$, $Co_3O_4$. Especially, no considerable effects were observed by $TiO_2$, $Fe_2O_3$, and $Co_3O_4$ under tested concentration (max. 1,000 mg/L). The evaluation results of interactive toxic effects using various bioassays may comprise a useful tool for the bioassessment of various environmental pollutants.

• Research in Plant Disease
• /
• v.12 no.3
• /
• pp.260-266
• /
• 2006

Pythium blight caused by Pythium spp. is one of major diseases in putting green of golf course. In this study, microorganisms which are anatgonistic to Pythium aphanidermatum, a pathogen of pythium blight, were selected primary through in vitro tests, dual culture method and triple layer agar diffusion method. In vivo test against pythium blight were conducted to select the best candidate biocontrol microorganism by pot experiment in a plastic house. Bacillus subtilis GB-0365 was finally selected as a biocontrol agent against pythium blight. Relative Performance Indies(RPI) was used as a criterion of selecting potential biocontrol agent. B. subtilis GB-0365 showed resistance to major synthetic agrochemicals used in golf course. Alternative application of synthetic agrochemicals and B. subtilis GB-0365 was most effective to successfully contol pythium blight. B. subtilis GB-0365 suppressed the development of pythium bight of bentgrass by 56.4% as compared to non-treated control and its disease control efficacy was 60.9% of a synthetic fungicide Oxapro(WP) efficacy. B. subtilis GB-0365 has a potential to be a biocontrol agent for control of pythium blight.

• Korean Journal of Medicinal Crop Science
• /
• v.8 no.4
• /
• pp.342-350
• /
• 2000

This study was carried out to screen antioxidative by in vitro bioassay method from 89 Korean natural sources extracted by 100% MeOH. Antioxidant activity test was used the DPPH method. MeOH extracts from Castanea crenata and Ulmus davidiana var. japonica showed high antioxidant activity by $5.8{\mu}g\;(RC_{50})$ and $12.2{\mu}g\;(RC_{50})$, respectively, among 13 plants exhibiting the activity. The extracts from Platycarya strobilacea, Lindera erythrocarpa, Chrysanthemum boreale, Rumex crispus and Viburnum awabuki also showed over 90% antimicrobial activity, according to in vivo bioassay method.

• The Korean Journal of Applied Statistics
• /
• v.24 no.6
• /
• pp.1077-1094
• /
• 2011

We accomplish clustering analyses for yeast cell cycle microarray expression data. To reflect the characteristics of a time-course data, we screen the genes using the test statistics with Fourier coefficients applying a FDR procedure. We compare the results done by model-based clustering, K-means, PAM, SOM, hierarchical Ward method and Fuzzy method with the yeast data. As the validity measure for clustering results, connectivity, Dunn index and silhouette values are computed and compared. A biological interpretation with GO analysis is also included.

• Journal of Life Science
• /
• v.14 no.5
• /
• pp.761-769
• /
• 2004

This study was investigated the occurrence of sclerotinia rot caused by Sclerotinia sclerotiorum at the major perilla cultivating area, Gangdong-dong, Gangseo-gu, Busan in 1998. The incidence of this disease ranged from 8.1 to 28.3% at Gangdong-dong area during the growing seasons. Symptoms of the disease initially appeared damping-off of infected stems and soft-rot on the leaves of perilla. Under the relatively high humidity, abundant white mycelia of the pathogen formed on the lesion developed into black sclerotia later and the infected leaves were finally fell down. Sixteen isolates, Sl-S16, isolated from diseased lesions showing typical symptoms, and pathogenicity was tested using mycerlial disks. Among them, S2 isolate showing the most strong pathogenicity was selected and identified as Sclerotinia sclerotiorum on the basis of morphological and cultural characteristics. For biological control, an antagonistic bacteria, N4 isolate which effectively inhibited not only mycelial growth of S2 isolate but also suppress sclerotinia rot on the pot assay, was selected and identified as Bacillus megaterium according to Bergey's manual and API system., Wettable powder type, N4 formulation using B. megaterium N4 isolate was developed and estimated its control effect on perilla crops in a plastic house. As a results, N4 formulation which applied before 3 days inoculation of pathogen was effectually controlled Sclerotinia rot as the control value of 98.0%, was more effective than chemical fungicide, benomyl showing the control value of 78.0%. This is the first report of wettable powder formulation as a biocontrol agent using B. megaterium N4 against Sclerotinia rot caused by S. sclerotiorum on perilla.

• Korean Journal of Environmental Biology
• /
• v.19 no.4
• /
• pp.321-324
• /
• 2001

Groundwater samples were collected at 6 sites in Seoul area. DNA extraction from the sample was performed by the boiling method. Samples were boiled with guanidinium thyocyanate and phenol-chloroform. One set of primer was designed for amplification of 16S rDNA. For detection of denitrifying bacteria in groundwater sample, the author used primer sets consensus regions in gene sequences encoding the two forms of nitrite reductase (NIR), a key enzyme in the denitrification pathway. Two sets of PCR primer were designed to amplify $cd_1$-and Cu-nir. We confirmed the existence of denitrifying bacteria in 3 sites using $cd_1$-nir primer and in 4 sites using Cu-nir primer.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.13 no.4
• /
• pp.249-262
• /
• 2010

Regulatory test method for Total Petroleum Hydrocarbons (TPHs) in the marine sediment and biota has not still been established even though TPHs are one of the major pollutants in marine environment. Based on the Korean Soil Standard Method (SSM) for TPHs, we considered a new treatment method for determining TPHs in marine environmental samples by using a Gas chromatography coupled with Mass spectrometric detector. We suggested an improved recovery test for quality control procedures and introduced analytical procedures of removing sulfur, polar organic materials, water and saponification for removing neutral lipids in marine bottom sediments and biota.

• Korean Journal of Organic Agriculture
• /
• v.26 no.4
• /
• pp.649-660
• /
• 2018

To control the pepper anthracnose caused by Colletotrichum acutatum, antifungal bacterium strains which was selected among bacterium from natural soil, was tested the antimicrobial activity against various pathogens and its control efficacy on anthracnose disease in the fields. We confirmed that antagonistic activity of CAB13001 strain to pathogens such as Sclerotinia cepivorum, Sclerotinia sclerotium and Botrytis cinerea including Colletotrichum acutatum was remarkable superior with the dual culture method in the artificial medium. In vitro bioassay using the green pepper fruit, CAB13001 strain suppressed the lesion development of Anthracnose disease, and its control value compared to the untreated one was 82.4% on pepper fruit in field test. These results suggested that CAB13001 strain could be a very useful biological control agents to anthracnose disease caused by air born plant pathogens of pepper. By the way, analysis of nucleotide sequence of the gene 16S rDNA, antagonistic bacterium CAB13001 strain used in this study was identified as Burkholderia lata.

• The Korean Journal of Pesticide Science
• /
• v.4 no.4
• /
• pp.77-80
• /
• 2000

This study was carried out to investigate infection process, symptoms and $LD_{50}$ values of the entomopathogenic fungus cordyceps, Paecillomyces japonica, on the domestic silkworm, Bombyx mori. Susceptibility of infection in the silkworms by cordyceps, Paecillomyces japonica, was 100% in $10^{7}$ block, 96% in $10^{6}$ block, 76% in $10^{5}$ block, 44% in $10^{4}$ block, 28% in $10^{3}$ block and 8% in $10^{2}$ block. Cordyceps, Paecillomyces japonica, was highly infectious to the silkworms. A pathogenicities of cordyceps, Paecillomyces japonica, may be highly virulent because of the low resistance or high susceptibility of the silkworms. Dosage of the pathogen of $LD_{50}$ was $3.78{\times}10^{3}\;spores/mm^{3}$.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.31 no.6
• /
• pp.813-816
• /
• 1998

Toxicity and toxin compositions of wild and cultured scallops (Patinopecten yessoensis), collected from coastal waters near Kangnung of East Sea, were examined from January to June, 1997. By mouse bioassay methods, the toxicity was detected with low toxicity of $2 MU\;g^{-1}$, and paralytic shellfish poisoning (PSP) toxin was detected in the specimens from 30 April to 15 May by HPLC. GTXs and PXs were identified as the major toxin components.