• Journal of Microbiology and Biotechnology
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• 제25권7호
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• pp.1056-1069
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• 2015

Osmotic pressure is a critical factor for erythritol production with osmophilic yeast. Protein expression patterns of an erythritol-producing yeast, Yarrowia lipolytica, were analyzed to identify differentially-expressed proteins in response to osmotic pressure. In order to analyze intracellular protein levels quantitatively, two-dimensional gel electrophoresis was performed to separate and visualize the differential expression of the intracellular proteins extracted from Y. lipolytica cultured under low (3.17 osmol/kg) and high (4.21 osmol/kg) osmotic pressures. Proteomic analyses allowed identification of 54 differentially-expressed proteins among the proteins distributed in the range of pI 3-10 and 14.4-97.4 kDa molecular mass between the osmotic stress conditions. Remarkably, the main proteins were involved in the pathway of energy, metabolism, cell rescue, and stress response. The expression of such enzymes related to protein and nucleotide biosynthesis was inhibited drastically, reflecting the growth arrest of Y. lipolytica under hyperosmotic stress. The improvement of erythritol production under high osmotic stress was due to the significant induction of a range of crucial enzymes related to polyols biosynthesis, such as transketolase and triosephosphate isomerase, and the osmotic stress responsive proteins like pyridoxine-4-dehydrogenase and the AKRs family. The polyols biosynthesis was really related to an osmotic response and a protection mechanism against hyperosmotic stress in Y. lipolytica. Additionally, the high osmotic stress could also induce other cell stress responses as with heat shock and oxidation stress responses, and these responsive proteins, such as the HSPs family, catalase T, and superoxide dismutase, also had drastically increased expression levels under hyperosmotic pressure.

• Animal cells and systems
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• 제14권1호
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• pp.17-23
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• 2010

We isolated warm temperature acclimation-related protein 65-kDa (Wap65) cDNA from the liver of olive flounder and investigated the mRNA expression of Wap65 and HSP70 in olive flounder exposed to osmotic (17.5, 8.75, and 4 psu) and thermal stress (25 and $30^{\circ}C$). The mRNA expression of Wap65 and HSP70 was increased by thermal stress. The mRNA expression of HSP70 was also increased by osmotic stress, whereas no significant change in Wap65 expression was detected. These results indicate that Wap65 mRNA expression occurs specifically in response to increases in water temperature, but not in response to osmotic stress. Plasma cortisol levels were also increased by osmotic and thermal stress. We also utilized the stress hormone cortisol to examine whether Wap65 expression is thermal-stress-specific. Cortisol treatment increased HSP70 mRNA expression in vitro, but had no significant effect on Wap65 mRNA expression. Thus, thermal stress, but not osmotic stress, induces Wap65 expression.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 2002년도 제9회 학술 발표회 프로그램과 논문초록
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• pp.55-55
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• 2002

An alternative sigma factor as encoded by the $\sigma$$\^$B/ gene in Streptomyces coelicolor A3(2) was known to be involved in the differentiation and osmotic stress response. Protein expression profiles of wild-type and a $\sigma$$\^$B/ mutant strain of S coelicolor A3(2), which is impaired in defense against osmotic stress, were compared in the absence and presence of osmotic stress, using 2-dimentional gel electrophoresis.(omitted)

• Journal of Microbiology and Biotechnology
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• 제25권11호
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• pp.1787-1795
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• 2015

The transition from primary to secondary metabolism in antibiotic-producing Streptomyces correlates with expression of genes involved in stress responses. Consequently, regulatory pathways that regulate specific stress responses are potential targets to manipulate to increase antibiotic titers. In this study, genes encoding key proteins involved in regulation of the osmotic stress response in Streptomyces avermitilis, the industrial producer of avermectins, are investigated as targets. Disruption of either osaB_Sa, encoding a response regulator protein, or osaC_Sa, encoding a multidomain regulator of the alternative sigma factor SigB, led to increased production of both oligomycin, by up to 200%, and avermectin, by up to 37%. The mutations also conditionally affected morphological development; under osmotic stress, the mutants were unable to erect an aerial mycelium. In addition, we demonstrate the delivery of DNA into a streptomycete using biolistics. The data reveal that information on stress regulatory responses can be integrated in rational strain improvement to improve yields of bioactive secondary metabolites.

• Mycobiology
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• 제42권2호
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• pp.152-157
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• 2014

The iron uptake and utilization pathways play a critical role in allowing human pathogens, including Cryptococcus neoformans, the causative agent of fatal meningoencephalitis, to survive within the mammalian body by competing with the host for iron. Here we show that the iron regulon is also required for diverse environmental stress responses and that in C. neoformans, it is regulated by the high-osmolarity glycerol response (HOG) pathway. Between CFO1 and CFO2, two ferroxidase genes in the iron regulon, CFO1 but not CFO2 was induced during oxidative and osmotic stress. Interestingly, we found that the HOG pathway repressed basal expression of both CFO1 and CFO2. Furthermore, when the HOG pathway was blocked, CFO2 also responded to oxidative and osmotic stress and the response of CFO1 was increased. We also established that CFO1 plays a major role in responding and adapting to diverse environmental stresses, including oxidative and genotoxic damage, osmotic fluctuations, heavy metal stress, and stress induced by cell membrane destabilizers. Therefore, our findings indicate that in C. neoformans, the iron uptake and utilization pathways are not only required for iron acquisition and survival, but also play a significant role in the environmental stress response through crosstalk with the HOG pathway.

• Journal of Microbiology and Biotechnology
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• 제21권10호
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• pp.1064-1068
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• 2011

The osmotolerant yeast, Candida magnoliae, which was isolated from honeycomb, produces erythritol from sugars such as fructose, glucose, and sucrose. Erythrose reductase in C. magnoliae (CmER) reduces erythrose to erythritol with concomitant oxidation of NAD(P)H. Sequence analysis of the 5'-flanking region of the CmER gene indicated that one putative stress response element (STRE, 5'-AGGGG-3'), found in Saccharomyces cerevisiae, exists 72 nucleotides upstream of the translation initiation codon. An enzyme activity assay and semiquantitative reverse transcription polymerase chain reaction revealed that the expression of CmER is upregulated under osmotic and salt stress conditions caused by a high concentration of sugar, KCl, and NaCl. However, CmER was not affected by osmotic and oxidative stress induced by sorbitol and $H_2O_2$, respectively. The basal transcript level of CmER in the presence of sucrose was higher than that in cells treated with fructose and glucose, indicating that the response of CmER to sugar stress is different from that of GRE3 in S. cerevisiae, which expresses aldose reductase in a sugarindependent manner. It was concluded that regulation of CmER differs from that of other aldose reductases in S. cerevisiae.

• Fisheries and Aquatic Sciences
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• 제13권4호
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• pp.343-349
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• 2010

The effects of osmotic stress on the non-specific immune response of Nile tilapia, Oreochromis niloticus, were investigated. Osmoregulatory mechanism of tilapia has been studied, but less information is available about innate immune response of O. niloticus faced with hyperosmolality. Acute osmotic stress was elicited by transferring tilapia from freshwater (FW) to 24 psu seawater (SW). Non-specific immune parameters including lysozyme activities of plasma and head kidney (HK), alternative complement pathway (ACP) activity in plasma, phagocytic capacities of spleen and HK immune cells, and respiratory burst activity of immune cells in both HK and spleen were analyzed. Lysozyme activities were increased at 1 h and 30 h after transfer to SW, but decreased at 10 h after SW transfer. Conversely, ACP activity increased 10 h after SW transfer. Phagocytic capacity increased slightly at 1 h and 5 h after SW transfer, and respiratory burst activity showed an increase in superoxide release at 10 h after SW transfer. Taken together, these results indicate that the exposure of tilapia to hyperosmotic conditions has immunostimulatory effects on cellular and humoral immune reactions.

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2004년도 International Meeting of the Microbiological Society of Korea
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• pp.52-54
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• 2004

• Plant Biotechnology Reports
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• 제4권1호
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• pp.75-83
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• 2010

Glycine betaine has been reported as an osmoprotectant compound conferring tolerance to salinity and osmotic stresses in plants. We previously found that the expression of betaine aldehyde dehydrogenase 1 gene (OsBADH1), encoding a key enzyme for glycine betaine biosynthesis pathway, showed close correlation with salt tolerance of rice. In this study, the expression of the OsBADH1 gene in transgenic tobacco was investigated in response to salt stress using a transgenic approach. Transgenic tobacco plants expressing the OsBADH1 gene were generated under the control of a promoter from the maize ubiquitin gene. Three homozygous lines of $T_2$ progenies with single transgene insert were chosen for gene expression analysis. RT-PCR and western blot analysis results indicated that the OsBADH1 gene was effectively expressed in transgenic tobacco leading to the accumulation of glycine betaine. Transgenic lines demonstrated normal seed germination and morphology, and normal growth rates of seedlings under salt stress conditions. These results suggest that the OsBADH1 gene could be an excellent candidate for producing plants with osmotic stress tolerance.

• Mycobiology
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• 제37권3호
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• pp.161-170
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• 2009

Cryptococcus neoformans is a basidiomycete human fungal pathogen that causes meningoencephalitis in both immunocompromised and immunocompetent individuals. The ability to sense and respond to diverse extracellular signals is essential for the pathogen to infect and cause disease in the host. Four major stress-activated signaling (SAS) pathways have been characterized in C. neoformans, including the HOG (high osmolarity glycerol response), PKC/Mpk1 MAPK (mitogen-activated protein kinase), calcium-dependent calcineurin, and RAS signaling pathways. The HOG pathway in C. neoformans not only controls responses to diverse environmental stresses, including osmotic shock, UV irradiation, oxidative stress, heavy metal stress, antifungal drugs, toxic metabolites, and high temperature, but also regulates ergosterol biosynthesis. The PKC(protein kinase C)/Mpk1 pathway in C. neoformans is involved in a variety of stress responses, including osmotic, oxidative, and nitrosative stresses and breaches of cell wall integrity. The $Ca^{2+}$/calmodulin- and Ras-signaling pathways also play critical roles in adaptation to certain environmental stresses, such as high temperature and sexual differentiation. Perturbation of the SAS pathways not only impairs the ability of C. neoformans to resist a variety of environmental stresses during host infection, but also affects production of virulence factors, such as capsule and melanin. A drug(s) capable of targeting signaling components of the SAS pathway will be effective for treatment of cryptococcosis.