• 원예과학기술지
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• 제32권2호
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• pp.261-268
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• 2014

Senescence of Hosta ventricosa flowers was firstly characterized as ethylene-sensitive since the deterioration of the tepal was accompanied by increased endogenous ethylene biosynthesis. The full-length cDNAs and DNAs of 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS) and ACC oxidase (ACO) involved in ethylene biosynthesis were cloned from H. ventricosa flowers. The HvACS ORF with 1347 bp and two introns, encoded a polypeptide of 448 amino acids showing 79% homology with that in Musa acuminata. The HvACO ORF contained 957 bp and three introns, encoding a 318-residue polypeptide showing 83% homology with that in Narcissus tazetta. The timing of the induction of HvACS expression was in correspond to the timing of the increase in ethylene production, and that the up-regulation of HvACO transcript was closely correlated with an elevated ethylene production, but underwent a down-regulation in wounded leaves with elevated ethylene emission. The results, together with expression analysis in vegetative tissues, suggested that both HvACS and HvACO were specifically regulated by flower senescence.

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2002년도 추계학술대회
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• pp.135-139
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• 2002

Yeast cells respond to condition of amino acid starvation by synthesizing GCN4, a typical eukaryotic transcriptional activator, which regulates the expression of many amino acids biosynthetic genes. By introducing point mutations in the DNA binding domain of GCN4, mutants with normal DNA binding activity but defective in transcriptional activity were isolated to identify unknown proteins that could suppress the mutant phenotype under an amino acid depletion condition. As a result, SSB(Stress-Seventy B) subfamily proteins were identified as suppressors of mutant GCN4. SSB proteins were known as a member of yeast hsp70 family that probably aids passage of nascent chain through ribosomes. Among them, the mechanism of suppression by SSB2 on the defective GCN4 mutant strains is under investigation. Gcn4p directly interacts with Ssb2p through the basic DNA binding domain of GCN4. It suggests the possibility that physical interaction might induce the transcriptional activation of Gcn4p.

• Nutrition Research and Practice
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• 제4권4호
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• pp.270-275
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• 2010

Catecholamines are among the first molecules that displayed a kind of response to prolonged or repeated stress. It is well established that long-term stress leads to the induction of catecholamine biosynthetic enzymes such as tyrosine hydroxylase (TH) and dopamine ${\beta}$-hydroxylase (DBH) in adrenal medulla. The aim of the present study was to evaluate the effects of ginseng on TH and DBH mRNA expression. Repeated (2 h daily, 14 days) immobilization stress resulted in a significant increase of TH and DBH mRNA levels in rat adrenal medulla. However, ginseng treatment reversed the stress-induced increase of TH and DBH mRNA expression in the immobilization-stressed rats. Nicotine as a ligand of the nicotinic acetylcholine receptor (nAChR) in adrenal medulla stimulates catecholamine secretion and activates TH and DBH gene expression. Nicotine treatment increased mRNA levels of TH and DBH by 3.3- and 3.1-fold in PC12 cells. The ginseng total saponin exhibited a significant reversal in the nicotine-induced increase of TH and DBH mRNA expression, decreasing the mRNA levels of TH and DBH by 57.2% and 48.9%, respectively in PC12 cells. In conclusion, immobilization stress induced catecholamine biosynthetic enzymes gene expression, while ginseng appeared to restore homeostasis via suppression of TH and DBH gene expression. In part, the regulatory activity in the TH and DBH gene expression of ginseng may account for the anti-stress action produced by ginseng.

• International Journal of Oral Biology
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• 제31권3호
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• pp.93-98
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• 2006

Biosynthetic processing of fibrillar procollagens is essential for producing mature collagen monomers that polymerize into fibrils by a self-assembly process. The metalloproteinase ADAMTS-2 is the major enzyme that processes the N-propeptide of type I procollagen in the skin and also of type II and type III procollagens. Mutations in the ADAMTS-2 gene cause dermatospraxis in animals and Ehlers-Danlos syndrome VIIC in humans, both of which are characterized by the accumulation of type I pN-collagen and the formation of abnormal collagen fibrils in the skin. Despite its importance in procollagen processing, little is known about the regulation of ADAMTS-2 expression. Here, we demonstrate that ADAMTS-2 can be regulated by 1,25-dihydroxyvitamin D3, an inducer of type I procollagen synthesis. This steroid hormone induced ADAMTS-2 mRNA ${\sim}3-fold$ in MG-63 human osteosarcoma cells and MC3T3-E1 murine osteoblastic cells. This induction was dose- and time-dependent in MG-63 cells. In contrast, secreted ADAMTS-2 protein was increased only 1.4-fold with 1,25-dihydroxyvitamin D3. Finally, 1,25-dihydroxyvitamin D3 in the presence of ascorbate increased levels of secreted ADAMTS-2 1.9-fold over ascorbate treatment alone, which did not appreciably change ADAMTS-2 expression. These data indicate that the regulation of ADAMTS-2 is coupled with the synthesis of type I procollagen through 1,25-dihydroxyvitamin D3 signaling and may involve translational or posttranslational control.

• Journal of Plant Biotechnology
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• 제42권3호
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• pp.135-153
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• 2015

식물의 페닐알라닌, 티로신, 그리고 트립토판과 같은 방향족 아미노산은 단백질 합성의 구성 성분 뿐만 아니라 다양한 이차 대사물질들의 전구물질들이다. 이러한 방향족 아미노산 유래의 화합물들은 식물의 색소와 세포벽 구성성분을 포함하는 다양한 페놀릭 화합물들의 구성성분이자, 옥신과 살리실산과 같은 식물 호르몬으로써 중요한 역할을 수행한다. 또한 이들은 인간의 영양과 건강을 증진하는 높은 잠재력을 지니는 알칼로이드 및 글루코시놀레이트와 같은 천연산물로써 역할을 한다. 방향족 아미노산의 생합성경로는 shikimate 경로로부터 유래되는 공통의 중간기질인 chorismate를 공유한다. 트립토판은 중간기질로 anthranilate를 통해 합성되고, 페닐알라닌 및 티로신은 중간기질인 prephenate를 통해 합성된다. 본 논문에서는 방향족 아미노산 생합성경로에 관련한 모든 단계의 효소와 전사/전사후 수준에서의 그들의 유전자 조절에 대한 최근 연구들에 대해 종합적으로 되짚어 보면서, 추가적으로 식물의 방향족 아미노산 유래의 천연물질 생산을 증진시키기 위해 그 동안 시도되어온 대사 공학적 노력들에 대해서 소개하고자 한다.

• 원예과학기술지
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• 제29권6호
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• pp.511-522
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• 2011

화색은 화훼 육종의 주요한 목표형질이다. 최근 유전공학 기술의 발달로 기존의 전통육종에서는 볼 수 없었던 파란장미와 파란카네이션과 같은 새로운 화색 개발이 성공적으로 보고되었다. 플라보노이드 생합성에 관해 축적된 지식기반 연구 결과를 바탕으로 새롭고 독특한 형질의 화색을 도입하는 것이 가능하게 된 것이다. 이러한 화색변경은 플라보노이드 대사경로의 조절, 즉 내재유전자의 발현조절 및 새로운 플라보노이드 합성 또는 특정 플라보노이드 합성을 위한 외래유전자의 추가도입과 플라보노이드 대사 전체를 조절하는 전사인자의 도입을 통해서 이루어져 왔다. 그러나 보다 실증적으로 이러한 플라보노이드 대사를 조절하기 위해서는 작물별 내재 플라보노이드의 조절 기작에 대한 이해를 바탕으로 목표로 하는 플라보노이드 합성을 위해 보다 정교한 대사흐름의 조절이 요구된다. 본 총설에서는 화훼작물의 화색변경 성공 예들을 자세히 소개하고 그 요인 분석을 통해 향후 더 성공적인 화색변경의 전략을 수립하는데 도움이 되고자 한다.

• Journal of Applied Biological Chemistry
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• 제59권3호
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• pp.215-220
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• 2016

식물의 이차생장의 결과로 생산되는 바이오매스의 대부분은 식물의 이차세포벽에 축적된다. 식물의 이차세포벽은 크게 셀룰로스, 헤미셀룰로스, 리그닌이라는 3가지 물질로 구성되며 이들 중 페놀성 복합 화학 물질인 리그닌은 셀룰로스나 헤미셀룰로스와 달리 알코올 발효과정의 저해 물질로이다. 따라서, 식물의 이차세포벽 생합성의 과정을 조절함으로 전체 바이오매스의 생산량과 조성을 바이오 에너지 생산을 위해 최적 조건으로 조절함으로써 바이오 에탄올 생산을 최대화할 수 있을 것이다. 본 연구에서는 애기장대 유래 MYB7 유전자를 CaMV35S 프로모터 조절 하에서 과별현되게 한 식물체와 식물의 전사조절에서 하위 특정 유전자의 발현을 저해시키는 것으로 잘 알려진 SRDX 융합 단백질 즉, MYB7-SRDX 과발현체를 제작하여 그 특성을 조사하였다. 그 결과 MYB7 전사조절 인자가 리그닌의 생합성을 억제 조절한다는 결과를 관찰하였다. 이는 MYB7 전사조절인자를 이용하면 바이오 에탄올 발효과정에 저해 물질로 작용하는 리그닌을 경감시킬 수 있는 기초 자료로 사용할 수 있을 것이다.

• 한국식품위생안전성학회지
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• 제5권3호
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• pp.131-138
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• 1990

Aflatoxins is a chemically diverse group of toxic secondary metabolites that are produced by fungi and often occur in agricultural commodities. Because of their wide range of toxic effects, Aflatoxins cause severe economic losses to farmers and livestock producers and pose a health to human consuming contaminated foods. Long term prospects for biotechnological control of Aflatoxins require elucidation of the specific steps and regulation of their biosynthetic pathways . Aflatoxin determinations can be approached many ways. It is essential to safely handle all experimental materials associated with aflatoxin analysis or aflatoxigenic fungi Visual screening of suspect samples, base on the presence of conidial head of the aspergillus flavus group, and screening samples for the presence of bright greenish yellow flourescence are not chemical tests and such screening techniques may allow aflactoxin contaminated lots into commerce. Microcolumn screening procedures should always be used in conjunction with a quantitative method. Several thin layer chromatography(TLC) and high performance liquid chromatography(HPLC) methods are suitable for quantitation and are in general use. Immunochemical Methods such as the ELISA or affinity column chromatography methods are being rapidly developed. The chemical and immunochemical methods can be reliable if care is taken, using suitable controls and personnel that are well trained . All analytical laboratories should stress safety and include suitable analytical validation procedure. Especially a worldwide enquiry was undertaken in recent to obtain up-to-date information about aflatoxin legislation in as many countries of the world as possible. The information concerns aflatoxin in foodstuffs. aflatoxin MI in dairy products, aflatoxins in animal feedstuffs. Limits and regulations for aflatoxin have been expended in recent with more countries having legislation on subject, more products, and more aflatoxins covered by this legislation.

• Asian-Australasian Journal of Animal Sciences
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• 제23권8호
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• pp.1118-1126
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• 2010

Male reproduction is influenced by a number of intrinsic and extrinsic factors, including environmental endocrine disruptors. Testosterone is a well recognized intrinsic regulator for development and function of the male reproductive tract, and thus male fertility. The testis and semen of many mammalians contain an unusually high concentration of estrogen. Testosterone is converted into estrogen by the enzymatic action of cytochrome P450 aromatase complex (Cyp19a1). Of the male reproductive tract, the efferent ductules (EDs) possess exceptionally elevated levels of estrogen receptors (ERs), ER${\alpha}$ and ER${\beta}$, indicating that estrogen, in addition to testosterone, would have a functional role in regulation of male reproduction. First, this review has focused on description and summary of what is currently known for functions of estrogen in the EDs. The biosynthetic pathway of estrogen occurring in the testis is briefly covered, following by detailed explanation of the morphology and physiology of EDs. In the next section, the sources and targets of estrogen in the male reproductive tract are highlighted, and possible functional roles of estrogen in the EDs are justified from the aspect of physiology, molecular biology, and morphology in adult animal models. Also, this section covers the importance of estrogen and ERs in maintaining normal function and morphology of the EDs during postnatal development. In the last part of this review, the effects of extrinsic factors, especially environmental endocrine-disruptors, on the EDs is summarized. The intent of this review is to emphasize the importance of estrogen for regulation of physiological function of the EDs, and thus male fertility.

• 한국미생물·생명공학회지
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• 제14권5호
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• pp.427-432
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• 1986

The regulation of three ammonia assimilatory enzymes, GDH (glutamate dehydrogenase), GS (glutamine synthetase) and GOGAT (glutamate synthase), has been examined in C. glutamicum. Three kinds of arginine auxotrophs blocked in each step of arginine biosynthetic pathway from glutamate were selected as arg 5, arg 6, arg 8. Histidine and tryptophan auxotrophs were also selected because histidine and tryptophan repressed GS biosynthesis in E. coli. These strains were cultured on the media containing nitrogen-excess and limited conditions, to compare the specific activities of ${\alpha}$-ketoglutarate dehydrogenase(${\alpha}-KGDH$), GDH, GS, GOGAT from the cell-free extracts. These results showed that enzyme levels of ${\alpha}-KGDH$ and GDH from 3 kinds of arginine auxotrophs, histidine and tryptophan auxotrophs in nitrogen-excess condition and those of GS and GOGAT in nitrogen limited condition were increased compared with opposite condition. The tryptophan and histidine auxotrophs showed higher level of glutamate and glutamine than parental strains and other mutants. it is assumed that the higher levels of ${\alpha-KGDH}$ and GDH from mutants in nitrogen-excess condition promoted the accumulation of glutamate and glutamine in fermentation broth. The inhibition of GS activities by ADP suggested that GS is regulated by energy charge in C. glutamicum. The results with histidine, tryptophan, glycine, alanine, serine and GMP implied that a system of feedback inhibition were effective. The GDH, GS and GOGAT biosynthesis in culture broth was markedly repressed by the nature and kinds of available nitrogen sources such as tryptophan, proline, glycine, alanine, serine and tyrosine.