• Genes and Genomics
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• 제40권11호
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• pp.1199-1211
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• 2018

Soil acidification is one of major problems limiting crop growth and especially becoming increasingly serious in China owing to excessive use of nitrogen fertilizer. Only the STOP1 of Arabidopsis was identified clearly sensitive to proton rhizotoxicity and the molecular mechanism for proton toxicity tolerance of plants is still poorly understood. The main objective of this study was to investigate the transcriptomic change in plants under the low pH stress. The low pH as a single factor was employed to induce the response of the wheat seedling roots. Wheat cDNA microarray was used to identify differentially expressed genes (DEGs). A total of 1057 DEGs were identified, of which 761 genes were up-regulated and 296 were down-regulated. The greater percentage of up-regulated genes involved in developmental processes, immune system processes, multi-organism processes, positive regulation of biological processes and metabolic processes of the biological processes. The more proportion of down-regulation genes belong to the molecular function category including transporter activity, antioxidant activity and molecular transducer activity and to the extracellular region of the cellular components category. Moreover, most genes among 41 genes involved in ion binding, 17 WAKY transcription factor genes and 17 genes related to transport activity were up-regulated. KEGG analysis showed that the jasmonate signal transduction and flavonoid biosynthesis might play important roles in response to the low pH stress in wheat seedling roots. Based on the data, it is can be deduced that WRKY transcription factors might play a critical role in the transcriptional regulation, and the alkalifying of the rhizosphere might be the earliest response process to low pH stress in wheat seedling roots. These results provide a basis to reveal the molecular mechanism of proton toxicity tolerance in plants.

• Journal of Dairy Science and Biotechnology
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• 제33권1호
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• pp.83-91
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• 2015

Yogurt is a product of the acidic fermentation of milk, which affects the survival of lactic acid bacteria (LAB). The aim of this present study was to examine the survival and acid stress response of Lactobacillus rhamnosus GG to low pH environment. The survival of LAB in commercial yogurt was measured during long-term storage. The enumeration of viable cells of LAB was determined at 15-day intervals over 52-weeks at $5^{\circ}C$. L. acidophilus, L. casei, and Bifidobacterium spp. showed low viability. However, L. rhamnosus GG exhibited excellent survival throughout the refrigerated storage period. At the end of 52-weeks, L. rhamnosus GG survived 7.0 log10 CFU/mL. $F_0F_1$ ATPase activity in L. rhamnosus GG at pH 4.5 was also evaluated. The ATPase activities of the membranes were higher when exposed at pH 4.5 for 24 h. The survival of L. rhamnosus GG was attributable to the induction in $F_0F_1$ ATPase activity. In addition, the mRNA expression levels of acid stress-inducible genes at low pH were investigated by qRT-PCR. clpC and clpE genes were up-regulated after 1 h, and atpA and dnaK genes were up-regulated after 24 h of incubation at pH 4.5. These genes could enhance the survival of L. rhamnosus GG in the acidic condition. Thus, the modulation of the enzymes or genes to assist the viability of LAB in the low pH environment is thought to be important.

• 식물병연구
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• 제16권1호
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• pp.81-85
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• 2010

산성비 수준의 고농도 수소이온 스트레스인 pH 5.6-4.0 처리는 애기장대 생장에 크게 해를 주지 않았으며 강산성인 pH 3.5 이하에서 수소이온 농도가 높아질수록 식물 뿌리 및 줄기의 생장이 위축되었으며 특히 뿌리가 줄기보다 더 민감하게 반응하였다. 엽록소 함량은 pH 5.6-4.0까지 pH가 낮아질수확 증가히였다. pH 4.0에서 내려갈수록 점진적으로 엽록소 함량이 감소되는 경향을 보였으며 카로티노이드도 엽록소와 같은 경향을 보였으나 pH 3.5에서 함량이 가장 높았다. 안토시아닌은 pH가 낮아질 수록 계속 증가하여 pH 3.0에서 가장 많이 축적되었으며 pH 2.5에서는 급격히 감소되었다. 스트레스 강도가 세어 질수록 엽록소 대비 식물체내 카혹티노이드 및 안토시아닌 함량이 증가한다는 것은 엽록소를 보호하기 위한 식물의 생리적 반응으로 여겨진다. 그러나 안토시아닌과 카로티노이드는 수소이온 농도에 따른 식물체내 함량의 변화가 상이하여서 고수소이온 스트레스에서 식물의 보호하는 기작이 다를 것으로 에상된다.

• Bulletin of the Korean Chemical Society
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• 제34권11호
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• pp.3405-3409
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• 2013

The activation of heat shock factor 1 (HSF1) can be induced by the changes in environmental pH, but the mechanism of HSF1 activation by acidification is not completely understood. This paper reports that a low pH (pH~6.0) can trigger human HSF1 activation. Considering the involvement of the imidazole group of histidine residues under acid pH stress, an in vitro EMSA experiment, Trp-fluorescence spectroscopy, and protein structural analysis showed that the residue, His83, is the essential for pH-dependent human HSF1-activation. To determine the roles of His83 in the HSF1-mediated stress response affecting the cellular acid resistance, mouse embryo fibroblasts with normal wild-type or mutant mouse HSF1 expression were preconditioned by heating or pH stress. The results suggest that His83 is essential for HSF1 activation or the HSF1-mediated transcription of heat shock proteins, in protecting cells from acid pH stress.

• Animal cells and systems
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• 제7권4호
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• pp.345-348
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• 2003

The effects of acute acid stress on hatching success and hatching period of laboratory-reared hermaphroditic fish Rivulus marmoratus were examined. The effects of acute acid toxicity on mortality was also determined in three life stages of this fish. There was a significant negative effect of acid stress on hatching performance in the R. marmoratus embryos. The hatching success was only 5% at pH 3.5 compared to over 78% at pH higher than 4.0. The hatching period was also delayed by low pH treatments. The larval and juvenile stages were more sensitive to acid toxicity on mortality than the adult stage, but larvae and juveniles showed similar sensitivity. The 96-h LC50 value was pH 3.8 in larval and juvenile stages and pH 3.3 in adult stage.

• 한국수산과학회지
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• 제50권2호
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• pp.153-159
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• 2017

We examined changes in the physiological responses of gray mullet Mugil cephalus exposed to acidic seawater (pH 6.0, 6.5, 7.0) and normal seawater (pH 8.0, control) for 15 days. As pH decreased, survival rate and body weight also decreased. Levels of aminotransferase, total protein and triglycerides also differed significantly with changes in pH, presumably due to stress caused by exposure to acidic water. The level of osmotic pressure was significantly higher in the pH 6.0 group than in other groups. Superoxide dismutase was significantly higher in the pH 6.5 and 7.0 groups than in the pH 8.0 group, and glutathione level was lowest in the pH 6.0 group. We conclude that decreasing the pH level of seawater induces a stress response in fish, damaging their ability to control their hematological and osmotic pressure. Antioxidant enzymes are generally sensitive to osmotic stress; in this study, antioxidant activity significantly changed with pH level. These results indicate that physiological stress induced by exposure to acidification reduces survival rates and inhibits growth in M. cephalus.

• The Plant Pathology Journal
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• 제15권3호
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• pp.144-151
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• 1999

Chitinase activities from Shumard oak tissues were determined to study changes in chitinase activities related to water stress. The enzyme extracted in sodium acetate buffer (0.1M, pH 4.5) was assayed by a colorimetric method. In addition, the fungal hyphae of Hypoxylon atropunctatum in xylem tissues of oak were observed through scanning electron microscopy. The enzyme in oak tissues was mainly endochitinase, and optimum pH for enzyme activity was 5. Specific chitinase activities from both of stems held under high relative humidity (ranges of 0.63-1.11 pKatal/$\mu\textrm{g}$ of protein) and stems held under low relative humidity (ranges of 0.41-0.99 pKatal/$\mu\textrm{g}$ of protein) were significantly increased following fungal inoculation with H. atropunctatum. However, there was no significant difference in chitinase activities between tissues held under high and low humidities, which might be due to fungal chitinase. Scanning electron microscopy showed holes in fungal hyphae in the xylem tissues of stems held under high humidity but not in the stems held under ow humidity, suggesting that hyphae might be hydrolyzed by plant hydolases such as chitinase.

• 한국초지조사료학회지
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• 제34권4호
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• pp.262-268
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• 2014

In order to reveal the aluminum (Al) stress tolerance mechanisms in alfalfa plant at low pH soil, a proteomic approach has been conducted. Alfalfa plants were exposed to Al stress for 5 days. The plant growth and total chlorophyll content are greatly affected by Al stress. The malondialdehyde (MDA) and $H_2O_2$ contents were increased in a low amount but free proline and soluble sugar contents, and the DPPH-radical scavenging activity were highly increased. These results indicate that antioxidant activity (DPPH activity) and osmoprotectants (proline and sugar) may involve in ROS ($H_2O_2$) homeostasis under Al stress. In proteomic analysis, over 500 protein spots were detected by 2-dimentional gel electrophoresis analysis. Total 17 Al stress-induced proteins were identified, of which 8 protein spots were up-regulated and 9 were down-regulated. The differential expression patterns of protein spots were selected and analyzed by the peptide mass fingerprinting (PMF) using MALDI-TOF MS analysis. Three protein spots corresponding to Rubisco were significantly down-regulated whereas peroxiredoxin and glutamine synthetase were up-regulated in response to Al stress. The different regulation patterns of identified proteins were involved in energy metabolism and antioxidant / ROS detoxification during Al stress in alfalfa. Taken together, these results provide new insight to understand the molecular mechanisms of alfalfa plant in terms of Al stress tolerance.

• International Journal of Industrial Entomology and Biomaterials
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• 제33권2호
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• pp.102-107
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• 2016

Stress may be defined as any modification of environmental parameters that leads to a response by biological organisms. Stresses that affect biolpgical structures may be nonthermal, such as ultraviolet radiation, pH, or salinity, or thermal. Temperture is one of the major stresses that all living organism face. The major effects of cold(low emperature) are decrease of membrane fluidity and the stabilization of secondary structures of RNA and DNA in the cells, which may effect the efficiency of translation, transcription, and DNA replication. In this study, we focus on discovering the genes that are expressed by the cold(low temperature) stress in the silkworm. In cold(low temperature) stress test, we found 100% survive from cold stress at $0^{\circ}C$ up to 12h and $-5^{\circ}C$ up to 2h, and then, survive rate was rapidly decrease in silkworm. Thereafter two whole genes have selected by SSH(Suppression subtractive hybridization). (GenBank accession : GQ149511, GQ338156)

• 생명과학회지
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• 제27권7호
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• pp.826-833
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• 2017

대기의 이산화탄소의 농도 증가는 해양산성화와 지구온난화를 유발하는 것으로 알려져 있다. 해마는 해양생태계 및 수산자원생물로서 중요한 종으로 알려져 있지만, 최근 해양산성화로 인하여 개체수가 감소되고 있는 실정이다. 따라서 본 연구에서는 멸종 위기 종인 복해마(Hippocampus kuda)에 미치는 생리적 영향을 조사하기 위해서 사육수의 산성조건인 pH 6.0, 6.5, 7.0 및 자연해수(pH 8.0)의 환경에서 복해마(H. kuda)를 15일 동안 사육 후 체내 조성 변화 및 항산화 효소 활성 변화에 대하여 조사를 실시하였다. 복해마(H. kuda)의 크기 및 성장은 대조군인 pH 8.0을 제외한 실험군에서는 pH가 저하함에 따라 감소하는 경향을 나타내었다. 체내 조성성분인 회분, 조지방 및 조단백 또한 pH 저하에 따라 농도의존적으로 감소하는 것이 관찰되었다. SOD, CAT 및 GSH와 같은 항산화 효소의 분석 결과, SOD활성의 경우, pH 저하에 따라 농도의존적으로 감소하지만, 이와 상반되게 CAT 및 GSH에서는 pH저하에 따라 활성이 농도의존적으로 증가하는 결과가 나타내었다. 이것은 복해마(H. kuda)가 사육수의 pH 저하에 따른 체내 항상성을 유지하는 과정 중 스트레스가 야기되어 에너지 대사가 손상된 것으로 추정된다. 항산화효소는 일반적으로 산성화 스트레스에 민감하게 작용하는데 본 연구에서도 사육수의 pH 변화에 따라 항산화 효소작용이 유의하게 변화하였다. 이러한 결과로 복해마(H. kuda)에 있어서 산성화 노출을 통한 생리학적 스트레스가 항산화 반응 및 체내 성분과 성장을 저해하는 것으로 여겨진다.