• Journal of Microbiology and Biotechnology
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• 제19권10호
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• pp.1250-1258
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• 2009

Bacillus spp., as a type of plant growth-promoting rhizobacteria (PGPR), were studied with regards promoting plant growth and inducing plant systemic resistance. The results of greenhouse experiments with tobacco plants demonstrated that treatment with the Bacillus spp. significantly enhanced the plant height and fresh weight, while clearly lowering the disease severity rating of the tobacco mosaic virus (TMV) at 28 days post-inoculation (dpi). The TMV accumulation in the young non-inoculated leaves was remarkably lower for all the plants treated with the Bacillus spp. An RT-PCR analysis of the signaling regulatory genes Coil and NPR1, and defense genes PR-1a and PR-1b, in the tobacco treated with the Bacillus spp. revealed an association with enhancing the systemic resistance of tobacco to TMV. A further analysis of two expansin genes that regulate plant cell growth, NtEXP2 and NtEXP6, also verified a concomitant growth promotion in the roots and leaves of the tobacco responding to the Bacillus spp.

• The Plant Pathology Journal
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• 제30권3호
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• pp.323-329
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• 2014

Two cultivars Buram-3-ho (susceptible) and CR-Hagwang (moderate resistant) of kimchi cabbage seedlings showed differential defense responses to anthracnose (Colletotrichum higginsianum), black spot (Alternaria brassicicola) and black rot (Xanthomonas campestris pv. campestris, Xcc) diseases in our previous study. Defense-related hormones salicylic acid (SA), jasmonic acid (JA) and ethylene led to different transcriptional regulation of pathogenesis-related (PR) gene expression in both cultivars. In this study, exogenous application of SA suppressed basal defenses to C. higginsianum in the 1st leaves of the susceptible cultivar and cultivar resistance of the 2nd leaves of the resistant cultivar. SA also enhanced susceptibility of the susceptible cultivar to A. brassicicola. By contrast, SA elevated disease resistance to Xcc in the resistant cultivar, but not in the susceptible cultivar. Methyl jasmonate (MJ) treatment did not affect the disease resistance to C. higginsianum and Xcc in either cultivar, but it compromised the disease resistance to A. brassicicola in the resistant cultivar. Treatment with 1-aminocyclopropane-1-carboxylic acid (ACC) ethylene precursor did not change resistance of the either cultivar to C. higginsianum and Xcc. Effect of ACC pretreatment on the resistance to A. brassicicola was not distinguished between susceptible and resistant cultivars, because cultivar resistance of the resistant cultivar was lost by prolonged moist dark conditions. Taken together, exogenously applied SA, JA and ethylene altered defense signaling crosstalk to three diseases of anthracnose, black spot and black rot in a cultivar-dependent manner.

• 한국정보처리학회논문지
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• 제4권10호
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• pp.2512-2520
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• 1997

B-ISDN 사용자 망 접면에서 호/연결 제어를 위한 신호 기능은 ITU-T의 Q.2931과 ATM Forum의 UNI 3.1이 대표적이다. 점대점 호/연결 제어 절차를 제공하는 Q.2931은 공중망을 구성하는 장치에 적용이 되며, ATM Forum의 UNI 3.1은 여러 가지의 단말 장치 위주의 ATM 사설망을 구성하는데 적용된다. 국내의 B-ISDN 개발 사업에서는 방 장치인 ATM소형 교환기, B-NT 등과 단말장치인 B-TA등을 개발하였다. 그러나 B-ISDN에서 다양한 서비스를 제공하기 위해서는 여러 종류의 단말장치들을 필요로 한다. 공중망에서 UNI 3.1 단말 장치를 수용할 수 있다면, 여러 종류의 단말장치들을 확보할 수 있으므로 매우 효율적이다. 그러므로, 본 논문에서는 B-ISDN 공중망에 UNI 3.1 단말 장치를 접속하여 점대점 신호 절차 수행 시에 발생할 수 있는 문제점들을 예측하고, 호/연결이 원만하게 진행될 수 있는 방안들을 제안한다.

• Journal of Microbiology and Biotechnology
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• 제11권5호
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• pp.804-811
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• 2001

In many Gram-negative bacteria, autoinducers, such as N-acyl-L-homoserine lactone(acyl-HSL) and its derivative molecules, mediate the cell-density-dependnet expression of certain operons. The current study identified the autoinducers produced by Burkholderia cepacia G4, a trichloroethylene-degrading lagoon isolate, using TLC bioassays with Agrobacterium tumefaciens NT1(pDCI141E33) and Chromobacterium violaceum CVO26, and a GC-MS analysis. The ${R_f}\;and\;{R_t}$ values and mass spectra were compared with those of synthetic compounds. Based on the analyses, it was confirmed that G4 produces N-hexanoyl (C6)-, N-octanoyl (C8)-, N-decanoyl (C10)-, N-dodecanoyl (C12)-HSL, and an unknown active species. The integration of the GC peak areas exhibited a ratio of C8-HSL:C10-HSL:C12-HSL at 3:17:1 with C6-HSL and C10-HSL production at trace and micromolar levels, respectively, in the culture supernatants. Nutants partially defective in producing acyl-HSLs were also partially defective in the biosynthesis of an antibiotic substance. These results indicate that the autoinducer-dependent gene regulation in G4 is dissimilar to the clinical B. cepacia strains isolated from patients with cystic fibrosis.

• The Plant Pathology Journal
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• 제30권2호
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• pp.220-227
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• 2014

The GacS/GacA system in the root colonizer Pseudomonas chlororaphis O6 is a key regulator of many traits relevant to the biocontrol function of this bacterium. Proteomic analysis revealed 12 proteins were down-regulated in a gacS mutant of P. chlororaphis O6. These GacS-regulated proteins functioned in combating oxidative stress, cell signaling, biosynthesis of secondary metabolism, and secretion. The extent of regulation was shown by real-time RT-PCR to vary between the genes. Mutants of P. chlororaphis O6 were generated in two GacS-regulated genes, trpE, encoding a protein involved in tryptophan synthesis, and prnA, required for conversion of tryptophan to the antimicrobial compound, pyrrolitrin. Failure of the trpE mutant to induce systemic resistance in tobacco against a foliar pathogen causing soft rot, Pectobacterium carotovorum SCCI, correlated with reduced colonization of root surfaces implying an inadequate supply of tryptophan to support growth. Although colonization was not affected by mutation in the prnA gene, induction of systemic resistance was reduced, suggesting that pyrrolnitrin was an activator of plant resistance as well as an antifungal agent. Study of mutants in the other GacS-regulated proteins will indicate further the features required for biocontrol-activity in this rhizobacterium.

• Nutritional Sciences
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• 제7권1호
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• pp.23-30
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• 2004

As a central component of a novel protein kinase cascade, the activation of the mitogen-activated protein (MAP) kinase cascade has attracted considerable attention. We sought to determine the effect of exercise and diet on the activation of the extracellular-signal regulated protein kinase (ERK) 1/2 and the p38 MAP kinase pathways in rat soleus muscle. Forty-eight Sprague-Dawley rats were assigned to one of two dietary conditions: high-carbohydrate (CHO) or high-fat (FAT). Animals having each dietary condition were further divided into one of three subgroups: a sedentary control group that did not exercise (NT), a group that performed 8 weeks of treadmill running and was sacrificed 48 h after their final treadmill run (CE), and a group that was sacrificed immediately after their final routine exercise training (AE). A high-fat diet did not have any significant effect on phosphorylated and total forms of ERK 1/2 or p38 MAP kinase. In chronically trained muscle that was taken 48 h after the last training, phosphorylated ERK 1/2 significantly increased only in the FAT but not in the CHO groups. In the case of total ERK 1/2, it increased significantly for both groups. In contrast, both phosphorylated and total forms of p38 MAP kinase decreased markedly compared to sedentary muscle. In muscle that was taken immediately after a last bout of exercise, phosphorylated ERK 1/2 increased in both groups but statistical significance was seen only in the CHO group. Total ERK 1/2 in acutely stimulated muscle increased only in the CHO-AE group even though the degree was much lower than the phosphorylated status. Muscle that was taken immediately after the routine training increased in phosphorylation status of p38 MAP kinase for both dietary conditions. However, statistical significance was seen only in the CHO group owing to a large variation with FAT. In conclusion, a high-fat diet per se did not have any notable effect versus a high-carbohydrate diet on MAP kinase pathways. However, when diet (either CHO or FAT) was combined with exercise and/or training, there was differentiated protein expression in MAP kinase pathways. This indicates MAP kinase pathways have diverse control mechanisms in slow-twitch fibers.

• 한국축산식품학회지
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• 제26권3호
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• pp.402-409
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• 2006

Although microorganisms are, in fact, the most diverse and abundant type of organism on Earth, the ecological functions of microbial populations remains poorly understood. A variety of bacteria including marine Vibrios encounter numerous ecological challenges, such as UV light, predation, competition, and seasonal variations in seawater including pH, salinity, nutrient levels, temperature and so forth. In order to survive and proliferate under variable conditions, they have to develop elaborate means of communication to meet the challenges to which they are exposed. In bacteria, a range of biological functions have recently been found to be regulated by a population density-dependent cell-cell signaling mechanism known as quorum-sensing (QS). In other words, bacterial cells sense population density by monitoring the presence of self-produced extracellular autoinducers (AI). N-acylhomoserine lactone (AHL)-dependent quorum-sensing was first discovered in two luminescent marine bacteria, Vibrio fischeri and Vibrio harveyi. The LuxI/R system of V. fischeriis the paradigm of Gram-negative quorum-sensing systems. At high population density, the accumulated signalstrigger the expression of target genes and thereby initiate a new set of biological activities. Several QS systems have been identified so far. Among them, an AHL-dependent QS system has been found to control biofilm formation in several bacterial species, including Pseudomonas aeruginosa, Aeromonas hydrophila, Burkholderia cepacia, and Serratia liquefaciens. Bacterial biofilm is a structured community of bacterial cells enclosed in a self-produced polymeric matrix that adheres to an inert or living surface. Extracellular signal molecules have been implicated in biofilm formation. Agrobacterium tumefaciens strain NT1(traR, tra::lacZ749) and Chromobacterium violaceum strain CV026 are used as biosensors to detect AHL signals. Quorum sensing in lactic acid bacteria involves peptides that are directly sensed by membrane-located histidine kinases, after which the signal is transmitted to an intracellular regulator. In the nisin autoregulation process in Lactococcus lactis, the NisK protein acts as the sensor for nisin, and NisR protein as the response regulator activatingthe transcription of target genes. For control over growth and survival in bacterial communities, various strategies need to be developed by which receptors of the signal molecules are interfered with or the synthesis and release of the molecules is controlled. However, much is still unknown about the metabolic processes involved in such signal transduction and whether or not various foods and food ingredients may affect communication between spoilage or pathogenic bacteria. In five to ten years, we will be able to discover new signal molecules, some of which may have applications in food preservation to inhibit the growth of pathogens on foods.

• 한국정보과학회논문지:정보통신
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• 제29권4호
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• pp.375-385
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• 2002

IETF에서는 높은 대역폭과 낮은 지연시간을 요구하는 음성 및 영상 스트림을 포함한 새로운 종류의 응용 서비스의 QoS를 지원하기 위한 Intserv와 RSVP를 정의하고 있다. 그러나, 현재의 Intserv 모델에서는 각 노드가 각 flow의 상태를 유지해야 하므로, 망의 규모가 커질수록 노드의 구조가 복잡해지고 패킷의 처리 속도도 저하되는 문제점을 안고 있다. 본 논문에서는 이러한 stateful 망 구조의 확장성 문제를 극복하기 위해, core 노드에서 각 flow 상태를 유지하지 않고 edge 노드에서만 각 flow 상태를 유지하도록 제안된 SCORE(Scalable Core) 네트워크 구조를 Intserv 의 각 서비스 QoS를 만족시킬 수 있도록 확장하였으며, 이를 위한 수락제어, 대역폭 할당 방식 및 노드 구조를 제안하였다. 또한, 각 flow에 대한 대역폭 할당. 패킷 지연 및 지연시간의 변이를 성능 변수로 하여, 제안 방식에 대한 성능 실험을 ns-2 시뮬레이터를 이용하여 수행하였으며, 이를 통해 제안 방식이 Intserv에서 제시한 각 서비스의 서비스 품질 요구 사항을 충분히 만족시키면서 Intserv 모델의 단점인 확장성을 문제를 해결할 수 있는 좋은 방안임을 확인하였다.