• The Korean Journal of Mycology
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• v.23 no.2 s.73
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• pp.129-138
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• 1995

DNA fragment being able to restore in vitro activity of ${\beta}-1,3-glucan$ synthase was cloned by transformation of the Saccharomyces cerevisiae LP353 mutant strain with genomic library constructed in the YCp50. For the selection of transformants which showed no detectable phenotype linked to recovery of the defect in ${\beta}-1,3-glucan$ synthase activity, the colony autoradiography was succesfully applied. The restriction map of the cloned DNA fragment, which is 8.5-kb in length, was constructed. Both the YEplac195 and the YCp50 carrying the 8.5-kb fragment increased ${\beta}-1,3-glucan$ synthase activity of LP353 by two fold. Neither the YEplac195 nor the YCp50 carrying the 8.5-kb DNA fragment, however, complemented the temperature-dependent osmotic sensitivity which is another distinctive phenotype of LP353. Subcloning experiments indicated that a functional region was located in 4.8-kb BglII-KpnI fragment. The 4.8-kb fragment was also able to increase the level of ${\beta}-1,3-glucan$ content in cell wall as well as the resistance of cells to cell wall lytic enzyme, ${\beta}-1,3-glucanase$. The growth rate of the LP353 with 4.8-kb fragment was almost same as that of wild type strain in liquid medium with 1.2 M sorbitol at nonpermissive temperature. Taken these results together, the 4.8-kb fragment seemed to contain the BGS2 gene for ${\beta}-1,3-glucan$ synthase activity in yeast S. cerevisiae.

• Korean Journal of Microbiology
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• v.46 no.4
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• pp.366-374
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• 2010

Culture-dependent RFLP and culture-independent DGGE were employed to investigate the bacterial community associated with the marine sponge Spirastrella abata. A total of 164 bacterial strains associated with the sponge were cultivated using Zobell and Natural sea salt media. PCR amplicons of the 16S rDNA from the bacterial strains were digested with the restriction enzymes HaeIII and MspI, and then assigned into different groups according to their restriction patterns. The 16S rDNA sequences derived from RFLP patterns showed more than 95% similarities compared with known bacterial species, and the isolates belonged to four phyla, Proteobacteria (Alphaproteobacteria, Gammaproteobacteria), Actinobacteria, Firmicutes, and Bacteriodetes, of which Alphaproteobacteria was dominant. DGGE fingerprinting of 16S rDNAs amplified from the sponge- derived total gDNA showed five major DGGE bands, and their sequences showed more than 96% similarities compared with available sequences. The sequences derived from DGGE bands revealed high similarity with the uncultured bacterial clones. DGGE revealed that bacterial community consisted of four phyla, including Proteobacteria (Alphaproteobacteria, Gammaproteobacteria), Actinobacteria, Spirochetes, and Chloroflexi. Alphaproteobacteria, Gammaproteobacteria, and Actinobacteria were commonly found in bacteria associated with S. abata by both RFLP and DGGE methods; however, overall bacterial community in the sponge differed depending on the analysis methods.

• Biomedical Science Letters
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• v.13 no.2
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• pp.75-81
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• 2007

Sodium salicylate (NaSal), a chemopreventive drug, has been shown to induce apoptosis and cell circle arrest depending on its concentrations in a variety of cancer cells. In A549 cells, low concentration of NaSal (5$\sim$10 mM) induces cell cycle arrest, whereas it induces apoptosis at higher concentration of 20 mM. In the present study, we examined the molecular mechanism for NaSal-induced cell cycle arrest. NaSal induced expression of p53, p21 (Wafl/Cipl), and p27 (Kipl) that play important roles in cell cycle arrest. p53 induction was mediated by its phosphorylation at Ser-15 that could be prevented by the PI3K-related kinase (ATM, ATR and DNA-PK) inhibitors including wortmannin, caffeine and LY294002. In addition, NaSal-induction of p2l (Wafl/Cipl) was detected in P53 (+/+) wild type A549 cells but not in p53 (-/-) mutant H1299 cells, indicating p53-dependent p21 (Wafl/Cipl) induction. In contrast, p27 (Kipl) that is a negative regulate. of cell cycle with p21 (Wafl/Cipl) was observed both in A549 cells and H1299 cells. Thus, 5 mM NaSal appeared to cause cell cycle arrest through inducing the cyclin-dependent kinase inhibitor p21 (Wafl/Cipl) via PI3K-related protein kinase-dependent p53 activation as well as by up-regulating p27 (Kipl) independently of p53 in A549 cells.

• Korean Journal of Biological Psychiatry
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• v.10 no.2
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• pp.159-167
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• 2003

Objective:Under the hypothesis that 5-HTTLPR polymorphism plays some role in the susceptibility or vulnerability of some subgroup of alcohol dependence, associations of 5-HTTLPR polymorphism with alcohol dependence were examined. Method:This association analysis included 109 Korean alcohol dependent and 113 Korean control subjects. DNA of all subjects were genotyped for the biallelic functional polymorphism in the 5-HTTLPR. Considering the likelihood of heterogeneity in the alcohol dependence phenotype, alcohol dependent subjects were subgrouped by onset age, family history of alcohol dependence and severity of withdrawal symptoms. Results:There were no significant differences in the frequencies of either the 5-HTTLPR genotype or the short vs. long allele in alcohol dependent and control subjects. The frequency of the S allele and S-carrier (LS or SS genotype) was significantly increased in the early onset alcohol dependent subjects and the familial alcohol dependent subjects compared with that in the control subjects. Conclusion:The results suggest that the 5-HTT 'S' promoter polymorphism is associated with an increased susceptibility or vulnerability to develop early onset alcohol dependence and familial alcohol dependence, which characterize Cloninger's type 2 alcohol dependence.

• Journal of Ginseng Research
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• v.31 no.1
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• pp.1-13
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• 2007

We found that the main bacterial metabolite M1 is an active component of orally administered protopanxadiol-type ginsenosides, and that the anti-metastatic effect by oral administration of ginsenosides may be primarily mediated through the inhibition of tumor invasion, migration and growth of tumor cells by their metabolite M1. Pharmacokinetic study after oral administration of ginsenoside Rb1 revealed that M1 was detected in serum for 24 h by HPLC analysis but Rb1 was not detected. M1, with anti-metastatic property, inhibited the proliferation of murine and human tumor cells in a time- and concentration-dependent manner in vitro, and also induced apoptotic cell death (the ladder fragmentation of the extracted DNA). The induction of apoptosis by M1 involved the up-regulation of the cyclin-dependent kinase(CDK) inhibitor $p27^{Kip1}$ as well as the down-regulation of a proto-oncogene product c-Myc and cyclin D1 in a time-dependent manner. Thus, M1 might cause the cell-cycle arrest (G1 phase arrest) in honor cells through the up/down-regulation of these cell-growth related molecules, and consequently induce apoptosis. The nucleosomal distribution of fluorescence-labeled M1 suggests that the modification of these molecules is induced by transcriptional regulation. Tumor-induced angiogenesis (neovascularization) is one of the most important events concerning tumor growth and metastasis. Neovascularization toward and into tumor is a crucial step for the delivery of nutrition and oxygen to tumors, and also functions as the metastatic pathway to distant organs. M1 inhibited the tube-like formation of hepatic sinusoidal endothelial (HSE) cells induced by the conditioned medium of colon 26-L5 cells in a concentration-dependent manner. However, M1 at the concentrations used in this study did not affect the growth of HSE cells in vitro.

• Toxicological Research
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• v.13 no.1_2
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• pp.39-48
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• 1997

Cyclophosphamide(25, 50 or 100 mg/kg), orally administered to male Sprague-Dawley rats, caused a time- and dose-dependent thymic atrophy. In the light microscopic examination of the atrophic thymus, thymocytes with condensed or fragmented nucleus were multifocally observed in the cortical region, started to increase 8 hr after CPA treatment and reached to the maximal level at 16 hr, although such cells were not seen after 48 hr when the severe depletion of thymocytes were marked. In agarose gel electrophoresis to analyze the DNA changes, DNA extracted from atrophic thymus showed a oligonucleosomal laddering at the corresponding time to morphological changes. In an additional supportive experiment, thymocytes showing morphological changes, nuclear condensation or apoptotic body, exhibited a positive reaction to immunoperoxidase staining using in situ apoptosis detection kit. Separately, agarose gel electrophoresis of DNA from bone .marrow cells was performed to investigate the involvement of bone marrow cells in the process of thymocyte apoptosis. Although DNA laddering was slightly increased 2 and 4 hr after treatment, no clear correlation was inferred. Taken togather, it is concluded that thymocytes showing morphological changes in thymic atrophy induced by cyclophosphamide administration represent an apoptosis having biochemical nature of programmed cell death.

• Journal of Food Hygiene and Safety
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• v.24 no.3
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• pp.267-272
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• 2009

The trace element nutrient selenium discharges its well-known nutritional anti-tumor activity. Converging data from epidemiological, ecological and clinical studies have shown that selenium can decrease the risk for some types of human cancers, especially those of the prostate, lung, and colon. Mechanistic studies have indicated that selenium has many desirable attributes of chemoprevention targeting cancer cells through DNA single strand breaks, the induction of reactive oxygen species. However, there is no reports about the relationship between methylseleninic acid (MSeA), one of methylselenol metabolites and cell cycle arrest in LNCaP human prostate cancer cells. Our data showed that MSeA arrested G1/S pahse of cell cycle arrest and inhibited DNA synthesis in LNCaP cells and those cellular events by MSeA were due to the induction ofp27 protein which is a well-known cyclin-dependent kinase inhibitor. Taken together, cell cycle arrest occurred by MSeA may contribute to the growth-inhibition of prostate cancer cells.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.6
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• pp.699-705
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• 1997

Although it is known that neuronal cell death during development occurs by apoptosis, the mechanisms underlying excitatory amino acid-induced neuronal cell death remain poorly understood. In this study we have examined the mechanism by which L-glutamate, an excitatory amino acid neurotransmitter, induces cell death in PC12 cell lines. To characterize cell death, we employed sandwich enzyme-linked immunosorbent assay(ELISA) method for cellular DNA fragmentation, DNA agarose gel electrophoresis and chromatin staining by acridine orange and ethidium bromide after treating the PC12 cells with L-glutamate. L-Glutamate caused dose-dependent cell death with a maximum at 24 hrs after the treatment. These cellular fragmentation was blocked by pretreatment of MK-801, a noncompetitive N-methyl-D-aspartic acid(NMDA) receptor antagonist, and nerve growth factor(NGF). Analysis of DNA integrity from L-glutamate-treated cells revealed cleavage of DNA into regular sized fragments, a biochemical hallmark of apoptosis. The PC12 cells that were induced to die by L-glutamate treatment exhibited classical chromatin condensation under the light microscopy after acridine orange and ethidium bromide staining. These results suggest that apoptosis is one of the key features that are involved in L-glutamate-induced excitotoxic cell death in PC12 cells, and these cell death are mediated by NMDA receptor and depend on NGF.

• The Korean Journal of Food And Nutrition
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• v.28 no.5
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• pp.759-765
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• 2015

The effects of extracts from Lentinula edodes (L. edodes) and Aquilariae agallocha (A. agallocha) on the DNA damage response in ultraviolet A (UVA)-exposed HaCaT cells and on the allergic contact dermatitis caused by 2,4-dinitro-chlorobezene (DNCB) were investigated. When UVA-exposed cells were incubated for 24 hours in medium containing L. edodes or A. agallocha extract, the level of 8-OHdG and CPD decreased in a concentration-dependent manner. The combined treatment with both extracts potentiated the decrease in UVA-induced 8-OHdG and CPD levels as compared with those following treatment with a single extract. In addition, the two extracts showed preventive effects against the UVA-induced reduction in collagen levels. Furthermore, the blood levels of IgE, IL-6, and histamine decreased more significantly upon combined treatment with L. edodes and A. agallocha extracts as compared with those following treatment with single extracts in DNCB-induced allergic contact dermatitis in the ICR mouse. The results of the present study suggest that the components with in the extracts of L. edodes and A. agallocha can help to prevent of UVA-induced genomic instability via a decrease in DNA damage, and to decrease the DNCB-induced allergic dermatitis via modulation of relevant proteins including IgE and IL-6. Further study is needed to clarify the purified components related to the preventative effects of the two extracts against UVA- or DNCB-induced genomic damage.

• Toxicological Research
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• v.34 no.4
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• pp.291-296
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• 2018

Chemical carcinogenesis is a multistep process. Genotoxic carcinogens, which are DNA-reactive, induce DNA adduct formation and genetic alterations in target cells, thereby generating mutated cells (initiation). Subsequently, preneoplastic lesions appear through clonal proliferation of the mutated cells and transform into tumors (promotion and progression). Many factors may influence these processes in a dose-dependent manner. Therefore, quantitative analysis plays an important role in studies on the carcinogenic threshold of genotoxic carcinogens. Herein, we present data on the relationship between key carcinogenic events and their deriving point of departure (PoD). Their PoDs were also compared to those of the carcinogenesis pathway. In an experiment, the liver of rats exposed to 2-amino-3,8-dimethylimidazo-(4,5-f)quinoxaline (MeIQx) was examined to determine the formation of MeIQx-DNA adducts, generation of mutations at LacI transgene, and induction of preneoplastic glutathione S-transferase placental form (GST-P)-positive foci and tumors (benign and malignant). The PoDs of the above key events in the carcinogenicity of MeIQx were increased as the carcinogenesis advanced; however, these PoDs were lower than those of tumor induction. Thus, the order of key events during tumor induction in the liver was as follows: formation of DNA adducts ${\ll}$ Mutations ${\ll}$ GST-positive foci (preneoplasia) ${\ll}$ Tumor (adenoma and carcinoma). We also obtained similar data on the genotoxic and carcinogenic PoDs of other hepatocarcinogens, such as 2-amino-3,8-dimethylimidazo(4,5-f)quinoline. These results contribute to elucidating the existence of a genotoxic and carcinogenic threshold.