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Kim SW, Hwang HJ, Xu CP, Na YS, Song SK, Yun JW. Influence of nutritional conditions on the mycelial growth and exopolysaccharide production in Paecilomyces sinclairii. Lett Appl Microbiol 2002; 34:389-93. [PMID: 12028416 DOI: 10.1046/j.1472-765x.2002.01105.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIMS The objective of the study was to optimize the submerged culture conditions for the production of exopolysaccharide from Paecilomyces sinclairii. METHODS AND RESULTS The optimal temperature and initial pH for exopolysaccharide production by Paecilomyces sinclairii in shake flask culture were found to be 30 degrees C and 6.0, respectively. Sucrose (60 g l(-1)) and corn steep powder (10 g l(-1)) were the most suitable carbon and nitrogen source for exopolysaccharide production. CONCLUSIONS Under optimal culture medium, the maximum exopolysaccharide concentration in a 5-l stirred-tank fermenter indicated 7.4 g l(-1), which was approximately three times higher than that in basal medium. The maximum specific growth rates (micro max) and yield coefficient (Y(P/S)) in the optimal culture medium was 0.16 h(-1) and 0.19, respectively. SIGNIFICANCE AND IMPACT OF THE STUDY The optimal culture conditions reported in this article can be widely applied to the processes for submerged cultures of other mushrooms.
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Affiliation(s)
- S W Kim
- Department of Biotechnology, Taegu University, Kyungsan, Kyungbuk, Korea
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52
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Kim SW, Hwang HJ, Park JP, Cho YJ, Song CH, Yun JW. Mycelial growth and exo-biopolymer production by submerged culture of various edible mushrooms under different media. Lett Appl Microbiol 2002; 34:56-61. [PMID: 11849494 DOI: 10.1046/j.1472-765x.2002.01041.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIMS The effect of synthetic media on the submerged mycelial growth and exo-biopolymer production in various edible mushrooms was investigated in shake flask culture. METHODS AND RESULTS Among 19 mushrooms examined, the relatively high yield in mycelial biomass and exo-biopolymer production was achieved in potato malt peptone (PMP) medium. In particular, Ganoderma lucidum NO. 1 and Phellinus linteus KCTC 6190 showed favourable growth in PMP medium with exo-biopolymer concentration of 1170 and 1520 mg l(-1), respectively. CONCLUSIONS Enhanced exo-biopolymer production was achieved from Ganoderma lucidum NO. 1 and Phellinus linteus KCTC 6190 in a 5L batch fermentor, indicating approximately 5000 and 2410 mg l(-1), respectively. SIGNIFICANCE AND IMPACT OF THE STUDY The exo-biopolymer production and mycelial growth from various mushrooms were found to be strongly controlled by different complex media.
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Affiliation(s)
- S W Kim
- Department of Biotechnology, Taegu University, Kyungsan, Kyungbuk 712-714, Korea
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53
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Abstract
Arginase (EC 3.5.3.1) was purified to homogeneity from root tissues of three-year-old ginseng (Panax ginseng C.A. Meyer), shade plant, and was found to be an extraordinarily large molecule relatively stable to heat. The enzyme was decameric having a molecular mass of 352,000 Da, with an optimal temperature and pH of 60 degrees C and 9.5, respectively. Analogues of arginine could not replace it as substrate, and a cysteine residue is at or near the active site. Maximum activity was obtained with Mn(2+) and Co(2+) also activated the proteins, whereas, both agmatine and 5'-deoxy-methylthioadenosine were inhibitors. Specific activities of the enzyme in sliced ginseng roots were increased by plant hormones such as GA(3), IAA, kinetin and putrescine, whereas the activities of the purified enzyme were unaffected by putrescine. Increases in arginase activities by these plant hormones could affect metabolism of polyamine intracellularly.
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Affiliation(s)
- H J Hwang
- Department of Biochemistry, College of Science, Yonsei University, Seoul 120-749, South Korea
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Piao W, Yoo J, Lee DK, Hwang HJ, Kim JH. Induction of G(2)/M phase arrest and apoptosis by a new synthetic anti-cancer agent, DW2282, in promyelocytic leukemia (HL-60) cells. Biochem Pharmacol 2001; 62:1439-47. [PMID: 11728380 DOI: 10.1016/s0006-2952(01)00796-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We studied the effect of DW2282-,[(S)-(+)-4-phenyl-1-[N-(4-aminobenzoyl)-indoline-5-sulfonyl-4,5-dihydro-2-imidazolone].hydrochloride], a newly developed anti-cancer agent, on cell proliferation, cell cycle progression, and induction of apoptosis in human promyelocytic leukemia (HL-60) cells. DW2282, a diarylsulfonylurea compound, was cytotoxic to HL-60 cells, with an IC(50) of 1.0 microg/mL. Treatment with DW2282 fragmented DNA in a concentration- and time-dependent manner, suggesting that these cells underwent apoptosis. Flow cytometric analysis further confirmed that DW2282-treated HL-60 cells were hypodiploid, in terms of DNA content, and were arrested at the G(2)/M phase. The cell cycle arrest was reversible upon the removal of DW2282. HL-60 cells also underwent distinct morphological changes in response to DW2282 treatment, including the appearance of elongated cells with conical tails and other apoptotic characteristics. G(2)/M phase cell cycle arrest was accompanied by a decrease in the levels of cdc2, a protein that plays a critical role for progression through the G(2)/M phase. Treatment of HL-60 cells with DW2282 was also associated with decreased levels of the anti-apoptotic protein Bcl-2, activation of caspase-3, and proteolytic cleavage of poly(ADP-ribose) polymerase. Taken together, these results demonstrate that DW2282 dramatically suppressed HL-60 cell growth by inducing apoptosis after G(2)/M phase arrest. These findings are consistent with the possibility that G(2)/M phase arrest was mediated by the down-regulation of cdc2 levels in HL-60 cells. The data also suggest that DW2282 triggered apoptosis by decreasing Bcl-2 levels and activating caspase-3 protease. These results provide important new information towards understanding the mechanisms by which DW2282 and other diarylsulfonylureas mediate their therapeutic effects.
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Affiliation(s)
- W Piao
- Department of Biochemistry, College of Dentistry, Kyung Hee University, 130-701, Seoul, South Korea
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55
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Kweon MH, Hwang HJ, Sung HC. Identification and antioxidant activity of novel chlorogenic acid derivatives from bamboo (Phyllostachys edulis). J Agric Food Chem 2001; 49:4646-4655. [PMID: 11600002 DOI: 10.1021/jf010514x] [Citation(s) in RCA: 151] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
One known and two novel antioxidant compounds have been isolated from bamboo (Phyllostachys edulis). The butanol-soluble extract of the bamboo leaves was found to have a significant antioxidant activity, as measured by scavenging the stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical and the superoxide anion radical (O(2)(-)) in the xanthine/xanthine oxidase assay system. Antioxidant activity-directed fractionation of the extract led to the isolation and characterization of three structural isomeric chlorogenic acid derivatives: 3-O-(3'-methylcaffeoyl)quinic acid (1), 5-O-caffeoyl-4-methylquinic acid (2), and 3-O-caffeoyl-1-methylquinic acid (3). Compounds 2 and 3 were isolated and characterized for the first time from the natural products. In the DPPH scavenging assay as well as in the iron-induced rat microsomal lipid peroxidation system, compounds 2 (IC(50) = 8.8 and 19.2 microM) and 3 (IC(50) = 6.9 and 14.6 microM) showed approximately 2-4 times higher antioxidant activity than did chlorogenic acid (IC(50) = 12.3 and 28.3 microM) and other related hydroxycinnamates such as caffeic acid (IC(50) =13.7 and 25.5 microM) and ferulic acid (IC(50) = 36.5 and 56.9 microM). Among the three compounds, compound 1 yielded the weakest antioxidant activity, and the DPPH scavenging and lipid peroxidation inhibitory activity (IC(50) = 16.0 and 29.8 microM) was lower than those of chlorogenic and caffeic acids. All three compounds exhibited both superoxide scavenging activities and inhibitory effects on xanthine oxidase. Their superoxide anion (O(2)(-)) scavenging activities (IC(50) = 1, 4.3 microM; 2, 2.8 microM; and 3, 1.2 microM) were markedly stronger than those of ascorbic acid (IC(50) = 56.0 microM), alpha-tocopherol (IC(50) > 100 microM), and other test compounds, although their inhibition effects on xanthine oxidase may contribute to the potent scavenging activity. alpha-Tocopherol exerted a significant inhibitory effect (65.5% of the control) on superoxide generation in 12-O-tetradecanoylphorbol-13-acetate-induced human promyelocytic leukemia HL-60 cells, and compound 3 showed moderate activity (36.0%). On the other hand, other compounds including 1, 2, chlorogenic acid, and other antioxidants were weakly active (24.8-10.1%) in the suppression of superoxide generation.
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Affiliation(s)
- M H Kweon
- Graduate School of Biotechnology, Korea University, 5-1 ka Anam-dong, Sungbuk-ku, Seoul 136-701, Korea
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56
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Abstract
We report the first structural characterization of the triplet isomer of C6. Forty-one rovibrational/fine structure transitions in the nu 4(sigma u) antisymmetric stretch fundamental of the C6 cluster have been measured by diode laser absorption spectroscopy of a supersonic carbon cluster beam. The observed spectrum is characteristic of a centrosymmetric linear triplet state with cumulene-type bonding. The measured ground state rotational constant B0 = 0.048 479 (10)cm-1 and the effective bond length r(eff) = 1.2868 (1) angstroms are in good agreement with ab initio predictions for the linear triplet (3 sigma g-) state of C6.
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Affiliation(s)
- H J Hwang
- Department of Chemistry, University of California, Berkeley 94720, USA
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57
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Park JP, Kim SW, Hwang HJ, Yun JW. Optimization of submerged culture conditions for the mycelial growth and exo-biopolymer production by Cordyceps militaris. Lett Appl Microbiol 2001; 33:76-81. [PMID: 11442820 DOI: 10.1046/j.1472-765x.2001.00950.x] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIMS The objective of the present study was to determine the optimal culture conditions for exo-biopolymer production by Cordyceps militaris in shake flask culture. METHODS AND RESULTS The optimal temperature and initial pH for both mycelial growth and exo-biopolymer production by Cordyceps militaris in shake flask culture were found to be 20 degrees C and 6.0, respectively. Sucrose (40 g x l(-1)) and corn steep powder (10 g x l(-1)) were the most suitable carbon and nitrogen source for both mycelial growth and exo-biopolymer production. CONCLUSION Under optimal culture conditions, the maximum exo-biopolymer concentration in a 5-l jar fermenter indicated 10.3 g x l(-1), which was approximately three times higher than that in shake flask culture. SIGNIFICANCE AND IMPACT OF THE STUDY This process can have a significant impact on the industrial scale when sucrose and corn steep powder were used as carbon and nitrogen source.
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Affiliation(s)
- J P Park
- Department of Biotechnology, Taegu University, Kyungsan, Kyungbuk, Korea
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58
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Abstract
This study was carried out to evaluate the application of food irradiation technology as a method for reducing milk allergies. Bovine alpha-casein (ACA) and beta-lactoglobulin (BLG) were used as milk proteins. Using milk-hypersensitive patients' immunoglobulin E (IgE) and rabbit IgGs individually produced to ACA and BLG, the changes of allergenicity and antigenicity of irradiated proteins were observed by competitive indirect enzyme-linked immunosorbent assay. Allergenicity and antigenicity of the irradiated proteins were changed with different slopes of the inhibition curves. The disappearance of the band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and increase of the turbidity showed that solubility of the proteins decreased by radiation, and this decrease might be caused by agglomeration of the proteins. These results indicated that epitopes on milk allergens were structurally altered by gamma irradiation.
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Affiliation(s)
- J W Lee
- The Team for Radiation Food Science and Biotechnology, Korea Atomic Energy Research Institute, Yusong, Taejon
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59
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Saldeña TA, Saraví FD, Hwang HJ, Cincunegui LM, Carra GE. Oxygen diffusive barriers of rat distal colon: role of subepithelial tissue, mucosa, and mucus gel layer. Dig Dis Sci 2000; 45:2108-14. [PMID: 11215723 DOI: 10.1023/a:1026411118033] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
The contributions of subepithelial tissue, mucosa, and mucus gel layer as restraints for oxygen diffusion in rat distal colon in vitro were assessed by comparing oxygen transfer through preparations of isolated submucosa, isolated mucosa with and without the superficial mucus gel layer, and mucosa-submucosa mounted as flat sheets in a diffusion chamber. One side of the chamber was gassed with 95% O2-5% CO2 while the time course of oxygen concentration rise was measured in the continuously stirred opposite side, initially equilibrated with near-zero oxygen solution. The procedure does not affect epithelial viability. Diffusion in isolated mucosa was the same before and after KCN (5 mM) treatment, suggesting that epithelial oxygen consumption does not influence transfer rates. Subepithelial tissue, mucosa, and mucus gel layer are roughly responsible, respectively, for 12%, 56%, and 32% of oxygen diffusive hindrance. Diffusion coefficients range from 13% (mucosa-submucosa) to 54% (isolated submucosa) of that of water. Subepithelial tissue accounts for about 12% of total diffusive restraint.
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Affiliation(s)
- T A Saldeña
- Cátedra de Física Biológica, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina
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Kim EK, Shon DH, Ryu D, Park JW, Hwang HJ, Kim YB. Occurrence of aflatoxin M1 in Korean dairy products determined by ELISA and HPLC. Food Addit Contam 2000; 17:59-64. [PMID: 10793855 DOI: 10.1080/026520300283595] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The occurrence of aflatoxin M1 (AFM1) in pasteurized milk and dairy products was investigated by using direct competitive enzyme-linked immunosorbent assay (ELISA) and high-performance liquid chromatography (HPLC). The recoveries of AFM1 from the samples spiked at levels between 5 and 500 pg/ml were 88.0-106.5% for pasteurized milk and 84.0-94.0% for yoghurt by ELISA. By HPLC, the recoveries were 103-120% for pasteurized milk and 87.0-93.0% for yoghurt. The limits of detection were found to be 2 pg/ml by ELISA and 10 pg/ml by HPLC. Among a total of 180 samples collected in Seoul, Korea, the incidence of AFM1 in pasteurized milk, infant formula, powdered milk and yoghurt was 76, 85, 75, and 83%, respectively, with a mean concentration of 18, 46, 200, and 29 pg/g, respectively, when determined by ELISA. These results obtained by ELISA were closely related to those by HPLC for AFM1 (r2 = 0.9783).
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Affiliation(s)
- E K Kim
- Graduate School of Biotechnology, Korea University, Seoul, Korea
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61
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Yoo SK, Yoon M, Park UJ, Han HS, Kim JH, Hwang HJ. A radioimmunoassay method for detection of DNA based on chemical immobilization of anti-DNA antibody. Exp Mol Med 1999; 31:122-5. [PMID: 10551259 DOI: 10.1038/emm.1999.20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
High selectivity provided by biomolecules such as antibodies and enzymes has been exploited during the last two decades for development of biosensors. Of particular importance are efficient immobilization methods for biomolecules in order to preserve their biological activities. In this study, we have evaluated immobilization strategies for an anti-DNA antibody on a self-assembled monolayer of omega-functionalized thiols. The antibody was immobilized via peptide bond formation between the primary amines in the antibody and the carboxyl groups on the self-assembled monolayer. The peptide bond coupling was achieved by activating COOH groups on the surface through N-Hydroxysuccimide (NHS)-ester formation, followed by acylation of NH2 group in the antibody. DNA binding activity of the immobilized antibody was examined by counting beta emission from 35S-labeled DNA.
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Affiliation(s)
- S K Yoo
- Department of Chemistry, Kyung Hee University, Seoul, Korea
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62
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Hwang BJ, Kim Y, Kim HB, Hwang HJ, Kim JH, Lee HS. Analysis of Corynebacterium glutamicum methionine biosynthetic pathway: isolation and analysis of metB encoding cystathionine gamma-synthase. Mol Cells 1999; 9:300-8. [PMID: 10420990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023] Open
Abstract
The metB gene encoding cystathionine y-synthase, the second enzyme of methionine biosynthetic pathway, was isolated from a pSL109-based Corynebacterium glutamicum gene library via complementation of an Escherichia coli metB mutant. A DNA-sequence analysis of the cloned DNA identified an open-reading frame of 1161 bp which encodes a protein with the molecular weight of 41,655 comprising of 386 amino acids. The putative protein product showed good amino acid-sequence homology to its counterpart in other organisms. Introduction of a plasmid carrying the cloned metB into the C. glutamicum resulted in a 10-fold increase in cystathionine gamma-synthase activities, demonstrating the identity of the cloned gene. The C. glutamicum metB mutant which was generated by the site-specific integration of the cloned DNA into its chromosome did not lose the ability to grow on glucose minimal medium lacking supplemental methionine. The growth rate of the mutant strain was also comparable to that of the parental strain. These data indicate that, in addition to the transsulfuration pathway, other methionine biosynthetic pathways may be present in C. glutamicum.
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Affiliation(s)
- B J Hwang
- Graduate School of Biotechnology, Korea University, Seoul
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63
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Park SH, Koh SS, Chun JH, Hwang HJ, Kang HS. Nrg1 is a transcriptional repressor for glucose repression of STA1 gene expression in Saccharomyces cerevisiae. Mol Cell Biol 1999; 19:2044-50. [PMID: 10022891 PMCID: PMC83997 DOI: 10.1128/mcb.19.3.2044] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Expression of genes encoding starch-degrading enzymes is regulated by glucose repression in the yeast Saccharomyces cerevisiae. We have identified a transcriptional repressor, Nrg1, in a genetic screen designed to reveal negative factors involved in the expression of STA1, which encodes a glucoamylase. The NRG1 gene encodes a 25-kDa C2H2 zinc finger protein which specifically binds to two regions in the upstream activation sequence of the STA1 gene, as judged by gel retardation and DNase I footprinting analyses. Disruption of the NRG1 gene causes a fivefold increase in the level of the STA1 transcript in the presence of glucose. The expression of NRG1 itself is inhibited in the absence of glucose. DNA-bound LexA-Nrg1 represses transcription of a target gene 10.7-fold in a glucose-dependent manner, and this repression is abolished in both ssn6 and tup1 mutants. Two-hybrid and glutathione S-transferase pull-down experiments show an interaction of Nrg1 with Ssn6 both in vivo and in vitro. These findings indicate that Nrg1 acts as a DNA-binding repressor and mediates glucose repression of the STA1 gene expression by recruiting the Ssn6-Tup1 complex.
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Affiliation(s)
- S H Park
- Department of Microbiology, College of Natural Sciences, Seoul National University, Seoul 151-742, Korea
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Hwang HJ, St James-Roberts I. Emotional and behavioural problems in primary school children from nuclear and extended families in Korea. J Child Psychol Psychiatry 1998; 39:973-9. [PMID: 9804030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
The changes occurring within Korean society provide an opportunity for studying the influence of family structure on children's emotional and behavioural problems. Children aged 7-13 years from two Korean cities were assessed for emotional and behavioural problems in school by their teachers, using the Children's Behaviour Questionnaire. In Study 1, 326 children from extended families were compared with demographically matched nuclear family children in the same school classes. In Study 2, a further sample of 204 extended family children was compared with pair-matched nuclear family children, in order to replicate the findings. Children from Study 1 were followed up 2.5 years later. Children from extended families had lower behaviour problems scores and the prevalence of serious problems was lower in extended family children. These differences were most marked in relation to externalising behaviour problems and were stable over the studies and time. Grandparents in extended families may increase children's resiliency by providing sources of attachment, affection, and knowledge, as well as having indirect effects through their support of parents. Consistent with recent ideas about the cognitive bases for behaviour problems, it may be that rules for behaviour derived from traditional cultural beliefs and values are internalised by children from extended families and generalise to prevent behaviour problems in school.
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Affiliation(s)
- H J Hwang
- Thomas Coram Research Unit, University of London, UK
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65
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Affiliation(s)
- J R Heath
- Department of Chemistry, University of California, Berkeley 94720, USA
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66
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Van Orden A, Giesen TF, Provencal RA, Hwang HJ, Saykally RJ. Characterization of silicon-carbon clusters by infrared laser spectroscopy: the nu 3(sigma u) band of linear Si2C3. J Chem Phys 1994; 101:10237-41. [PMID: 11539561 DOI: 10.1063/1.467904] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The nu 3(sigma u) fundamental vibration of 1 sigma g+ Si2C3 has been observed using a laser vaporization-supersonic cluster beam-diode laser spectrometer. Forty rovibrational transitions were measured in the range of 1965.8 to 1970.9 cm-1 with a rotational temperature of 10-15 K. A least-squares fit of these transitions yielded the following molecular constants: nu 3(sigma u)=1968.188 31(18) cm-1, B"=0.031 575 1(60) cm-1, and B'=0.031 437 4(57) cm-1. These results are in excellent agreement with recent Fourier transform infrared (FTIR) measurements of Si2C3 trapped in a solid Ar matrix [J. Chem. Phys. 100, 181(1994)] and with ab initio calculations [J. Chem. Phys. 100, 175 (1994)] which suggest cumulenic-like bonding for Si2C3, analogous to the isovalent C5 carbon cluster.
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Affiliation(s)
- A Van Orden
- Department of Chemistry, University of California, Berkeley 94720, USA
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67
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Abstract
The infrared absorption spectrum of a linear, 13-atom carbon cluster (C13) has been observed by using a supersonic cluster beam-diode laser spectrometer. Seventy-six rovibrational transitions were measured near 1809 wave numbers and assigned to an antisymmetric stretching fundamental in the 1 sigma g+ ground state of C13. This definitive structural characterization of a carbon cluster in the intermediate size range between C10 and C20 is in apparent conflict with theoretical calculations, which predict that clusters of this size should exist as planar monocyclic rings.
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Affiliation(s)
- T F Giesen
- Department of Chemistry, University of California, Berkeley 94720, USA
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68
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Abstract
We report improved measurements for the nu 6 antisymmetric stretch fundamental and observation of the (nu 6 + nu 15)-nu 15 and (nu 6 + 2 nu 15)-2 nu 15 hot bands of the linear C9 carbon cluster by direct absorption diode laser spectroscopy of a supersonic carbon cluster beam. Analysis of these bands characterizes C9 as a semirigid molecule with a bending potential similar to that of C5 and further evidences the alternation in degree of rigidity of linear carbon clusters with the g-u symmetry of the HOMO.
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Affiliation(s)
- A Van Orden
- Department of Chemistry, University of California, Berkeley 94720, USA
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69
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Hwang HJ, Sensharma DK, El-Sayed MA. Size and temporal dependence of the average kinetic-energy release during the evaporation of sputtered Cs(CsI)n+ clusters. Phys Rev Lett 1990; 64:808-811. [PMID: 10042083 DOI: 10.1103/physrevlett.64.808] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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