• Title/Summary/Keyword: growth regulator

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Identification of the Vibrio vulnificus fexA Gene and Evaluation of its Influence on Virulence

  • JU HYUN-MOK;HWANG IN-GYUN;WOO GUN-JO;KIM TAE SUNG;CHOI SANG HO
    • Journal of Microbiology and Biotechnology
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    • v.15 no.6
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    • pp.1337-1345
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    • 2005
  • Vibrio vulnificus is the causative agent of foodborne diseases such as gastroenteritis and life-threatening septicemia. Microbial pathogenicity is a complex phenomenon in which expression of numerous virulence factors is frequently controlled by a common regulatory system. In the present study, a mutant exhibiting decreased cytotoxic activity toward intestinal epithelial cells was screened from a library of V. vulnificus mutants constructed by a random transposon mutagenesis. By a transposon-tagging method, an open reading frame, fexA, a homologue of Escherichia coli areA, was identified and cloned. The nucleotide and deduced amino acid sequences of the fexA were analyzed, and the amino acid sequence of FexA from V. vulnificus was $84\%\;to\;97\%$ similar to those of AreA, an aerobic respiration control global regulator, from other Enterobacteriaceae. Functions of the FexA were assessed by the construction of an isogenic mutant, whose fexA gene was inactivated by allelic exchanges, and by evaluating its phenotype changes in vitro and in mice. The disruption of fexA resulted in a significant alteration in growth rate under aerobic as well as anaerobic conditions. When compared to the wild-type, the fexA mutant exhibited a substantial decrease in motility and cytotoxicity toward intestinal epithelial cell lines in vitro. Furthermore, the intraperitoneal $LD_{50}$ of the fexA mutant was approximately $10^{1}-10^{2}$ times higher than that of parental wild-type. Therefore, it appears that FexA is a novel global regulator controlling numerous genes and contributing to the pathogenesis as well as growth of V. vulnificus.

Two-component Signal Transduction in Synechocystis sp. PCC 6803 under Phosphate Limitation: Role of Acetyl Phosphate

  • Juntarajumnong, Waraporn;Eaton-Rye, Julian J.;Incharoensakdi, Aran
    • BMB Reports
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    • v.40 no.5
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    • pp.708-714
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    • 2007
  • The two-component signal transduction, which typically consists of a histidine kinase and a response regulator, is used by bacterial cells to sense changes in their environment. Previously, the SphS-SphR histidine kinase and response regulator pair of phosphate sensing signal transduction has been identified in Synechocystis sp. PCC 6803. In addition, some response regulators in bacteria have been shown to be cross regulated by low molecular weight phosphorylated compounds in the absence of the cognate histidine kinase. The ability of an endogenous acetyl phosphate to phosphorylate the response regulator, SphR in the absence of the cognate histidine kinase, SphS was therefore tested in Synechocystis sp. PCC 6803. The mutant lacking functional SphS and acetate kinase showed no detectable alkaline phosphatase activity under phosphate-limiting growth conditions. The results suggested that the endogenous acetyl phosphate accumulated inside the mutants could not activate the SphR via phosphorylation. On the other hand, exogenous acetyl phosphate could allow the mutant lacking functional acetate kinase and phosphotransacetylase to grow under phosphate-limiting conditions suggesting the role of acetyl phosphate as an energy source. Reverse transcription PCR demonstrated that the transcripts of acetate kinase and phospho-transacetylase genes in Synechocystis sp. PCC 6803 is up-regulated in response to phosphate limitation suggesting the importance of these two enzymes for energy metabolism in Synechocystis cells

Studies on Aseptic Culture of Seed in Dendrobium Monile I. Effects of Basal Media and Growth Regulators on Germination of Seeds and Growth of Plantlet (한약자원식물인 Dendrobium monile 종자의 무균배양에 관한 연구 I. 기본배지 및 생장조절 생질이 종자의 발아와 유묘 생육에 미치는 영향 ( Studies on Aseptic Culture of Seed in Dendrobium Monile I. Effect of Basal Media and Growth Regulators on Germination of Se)

  • 최성규
    • Korean Journal of Plant Resources
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    • v.1 no.1
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    • pp.88-92
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    • 1988
  • The study was conducted to determine the optimal basal media and the concentration of plant growth regulator for germination of seeds and growth of plantlet from Dendrobium monile. The results obtained were summarized as follows. Germination was similar in light and dark condition, but the growth of plantlet after germination was better under dark than under light condition in several media. Germination was best in Hyponex and Kyoto solution medium among the 9 media tested. The number of roots/shoot was most in the Hyponex medium containing 0,1ppm NAA and 1.Oppm BA.

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Effect of 2,4-Dichlorophenoxyacetic Acid and Kinetin on Peroxidase Isoenzymes in Ginseng(Panax ginseng C. A. Meyer) Callus Cultures (고려인삼(Panax ginseng C.A.Meyer) 조직배양에서 2.4-dichloro phenoxyacetic acid와 kinetin첨가가 Isoperoxidase 변이에 미치는 영향)

  • 김명원;강영희
    • Journal of Ginseng Research
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    • v.7 no.1
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    • pp.52-62
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    • 1983
  • This study was undertaken to investigate the influence of kinetin and 2, 4-dichlorophenoxyacetic acid on the rate of growth, the contents of RNA, DNA, and protein. And also the effect of plant growth regulator on isoperoxidases in callus derived from root (root-callus) and petiole (petiolecallus) was investigated. The rate of growth in petiole-callus was higher than the rootcallus at 0.1 mg/l kinetin and 1mgfl 2,4-D. At 1mgll kinetic, the rate of growth increased, but at high concentration the rate of growth decreased fast. The contents of RNA, DNA and protein also increased, but it did not coincide with the increase of the growth rate of callus. The isoperoxidases of callus grown at various amounts of 2,4-D and kinetic occurred in an almost fashion, but those of root-callus appeared different from those of petiole-callus.

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Allele-Specific Phenotype Suggests a Possible Stimulatory Activity of RCAN-1 on Calcineurin in Caenorhabditis elegans

  • Li, Weixun;Choi, Tae-Woo;Ahnn, Joohong;Lee, Sun-Kyung
    • Molecules and Cells
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    • v.39 no.11
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    • pp.827-833
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    • 2016
  • Regulator of calcineurin 1 (RCAN1) binds to calcineurin through the PxIxIT motif, which is evolutionarily conserved. SP repeat phosphorylation in RCAN1 is required for its complete function. The specific interaction between RCAN1 and calcineurin is critical for calcium/calmodulin-dependent regulation of calcineurin serine/threonine phosphatase activity. In this study, we investigated two available deletion rcan-1 mutants in Caenorhabditis elegans, which proceed differently for transcription and translation. We found that rcan-1 may be required for calcineurin activity and possess calcineurin-independent function in body growth and egg-laying behavior. In the genetic background of enhanced calcineurin activity, the rcan-1 mutant expressing a truncated RCAN-1 which retains the calcineurin-binding PxIxIT motif but misses SP repeats stimulated growth, while rcan-1 lack mutant resulted in hyperactive egg-laying suppression. These data suggest rcan-1 has unknown functions independent of calcineurin, and may be a stimulatory calcineurin regulator under certain circumstances.

Overexpression of GAP Causes the Delay of NGF-induced Neuronal Differentiation and the Inhibition of Tyrosine Phosphorylation of SNT in PC12 Cells

  • Yang, Sung-Il;Kaplan, David
    • BMB Reports
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    • v.28 no.4
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    • pp.316-322
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    • 1995
  • The GTPase activating protein (GAP) can function both as a negative regulator and an effector of $p21^{ras}$. Overexpression of GAP in NIH-3T3 cells has been shown to inhibit transformation by ms or src. To investigate the function of GAP in a differentiative system, we overexpressed this protein in the nerve growth factor (NGF)-responsive PC12 cell line. Two-fold overexpression of GAP caused a delay of several days in the onset of NGF- but not FGF-induced neuronal differentiation of PC12 cells. However, the NGF-induced activation or tyrosine phosphorylation of upstream (Trk, PLC-${\gamma}1$, SHC) and downstream (B-Raf and $p44^{mapk/erk1}$) components of $p21^{ras}$, signalling cascade was not altered by GAP overexpression. Therefore, the change of phenotype induced by GAP was probably not due to GAP functioning as a negative regulator of $p21^{ras}$. Rather, we found that NGF-induced tyrosine phosphorylation of SNT, a specific target of neurotrophin-induced tyrosine kinase activity, was inhibited by GAP overexpression. SNT is thought to function upstream or independent of $p21^{ras}$. Thus in PC12 cells, overexpressed GAP may control the rate of neuronal differentiation through a pathway involving SNT rather than the $p21^{ras}$ signalling pathway.

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Efficient Plant Regeneration from Shoot Tip and Young Leaf in Rhodiola sachalinensis A. Bor.

  • Chi, Hyung-Joon;Yoon, Jae-Ho;Yang, Deok-Chun;Song, Won-Seob
    • Plant Resources
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    • v.6 no.3
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    • pp.233-241
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    • 2003
  • The shoot tip and young leaf of Rhodiola sachalinensis were cultured to invest the plant growth regulator condition for callus induction, shoot and root regeneration. When the shoot tip was sterilized in 2.0% of NaOCl for 20min., the contamination rate was the lowest. And the survival rate of the culture material was good in carbenicillin 500mg/L treatment group. Callus was obtained from shoot tip and young leaf segments. NAA 0.1-1.0mg/L and 2,4-D 0.1-0.5mg/L alone treatment were shown to have a good response on callus induction from shoot tip culture. In the case of young leaf culture, NAA and 2,4-D 0.1-0.5mg/L alone treatment were good in callus induction. In culturing shoot tip NAA 0.5mg/L and BA 0.5mg/L, NAA1.0mg/L and BA 0.lmg/L combination treatment was good in shoot regeneration. The regenerated shoots were rooted on MS medium supplemented with NAA and BA combination treatment. Especially, NAA 1.0mg/L and BA 0.1mg/L combination treatment was effective for root regeneration.

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Plant Regeneration and Bulblet Formation of Allium wakegi Araki

  • Song, Won-seob;Yang, Deok-Chun;Yoon, Jae-Ho;Ryu, Sang-Hyun
    • Plant Resources
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    • v.7 no.1
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    • pp.7-14
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    • 2004
  • Allium wakegi was cultured shoot tip in the condition of light culture. The Allium wakegi added plant growth regulator was observed of plant regeneration and bulblet formation. Callus Induction and growing rate was the best of 78% when added alone 2,4-D 0.5mg/L. In the formation of shoot, its regeneration rate was 96% when added BA 0.5mg/L in the light culture condition. When BA 0.5mg/L and NAA 0.5mg/L mixed and BA 0.5 mg/L and NAA 1.0mg/L mixed, the rates were 99% and 97% respectively, and these conditions were suitable for forming shoot. In the formation of roots, when added NAA 2.0mg/L in the light culture condition, the regeneration rate was 90.6 % and the roots were abnormal. When added NAA 1.0mg/L, the rate was 82 % and the highest. In the formation of bulbs, when BA 05mg/L and NAA 1.0mg/L mixed, the root generantion and its size in the bulbs was the best compare to other treatment experiments.

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