• Journal of Microbiology and Biotechnology
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• v.28 no.9
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• pp.1457-1466
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• 2018

In the present study, the stabilizing effect of four different biological osmolytes on Bacillus licheniformis ${\gamma}$-glutamyl transpeptidase (BlGGT) was investigated. BlGGT appeared to be stable under temperatures below $40^{\circ}C$, but the enzyme retained less than 10% of its activity at $60^{\circ}C$. The tested osmolytes exhibited different degrees of effectiveness against temperature inactivation of BlGGT, and sucrose was found to be the most effective among these. The use of circular dichroism spectroscopy for studying the secondary structure of BlGGT revealed that the temperature-induced conformational change of the protein molecule could be prevented by the osmolytes. Consistently, the molecular structure of the enzyme was essentially conserved by the osmolytes at elevated temperatures as monitored by fluorescence spectroscopy. Sucrose was further observed to counteract guanidine hydrochloride (GdnHCl)-and urea-induced denaturation of BlGGT. Taken together, we observed evidently that some well-known biological osmolytes, especially sucrose, make a dominant contribution to the structural stabilization of BlGTT.

• Applied Biological Chemistry
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• v.38 no.3
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• pp.218-223
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• 1995

Osmolytes accumulated in the osmotically stressed Yersinia enterocolitica ATCC 9610 were investigated using natural abundance $^{13}C$ NMR spectroscopy. Glycine betaine, one of the more common and most effective osmolytes found in nature, was the dominant osmolyte in osmotically stressed Y. enterocolitica cells. Glycine betaine concentration was 41.8 times higher (801.9 nmol/mg protein) in stressed cells than in unstressed cells (19.2 nmol/mg protein). Proline was the minor osmolyte, and its concentration was 284.8 nmol/mg protein. The effects of glycine betaine and related osmolytes on growth rate of osmotically stressed Y. enterocolitica were investigated to identify their ability as osmolytes for Y. enterocolitica. When glycine betaine and proline were added in MMA medium containing 2.5% NaCl, the growth rate with glycine betaine (1 mM) was 3.6 times higher than in control (no addition of osmolyte), and that with proline was 1.3 times higher. Dimethylglycine (5 mM) also increased the growth rate 3.1 folds. On the other hand, monomethylElycine had no effect on growth of osmotically stressed and unstressed Y. enterocolitica. When carnitine was added in MMA medium containing 2.5% NaCl, carnitine (5 mM) increased the growth rate 2.4 folds, but choline had no effect on growth of osmotically stressed Y. enterocolitica. The above results indicate that glycine betaine is the dominant osmolyte in osmotically stressed Y. enterocolitica, and proline, dimethylglycine and carnitine also act as minor osmolytes.

• ALGAE
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• v.36 no.2
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• pp.123-135
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• 2021

The taxonomy of green microalgae relies traditionally on morphological traits but has been rapidly changing since the advent of molecular methods. Stichococcus Nägeli is a cosmopolitan terrestrial algal genus of the class Trebouxiophyceae that has recently been split into seven lineages, which, along with Pseudostichococcus, comprise the Stichococcuslike group; there is a need to further characterize these genera, since they are morphologically enigmatic. Here we used organic osmolytes as chemotaxonomic marker to verify the phylogenetic position of Stichococcus-like strains and were also able to exclude a strain hitherto identified as Gloeotila contorta from this group. Stichococcus-like organisms, including those recently revised, were characterized by the production of the polyol sorbitol and the disaccharide sucrose in high amounts, as is typical of Prasiola-clade algae. The results demonstrate that organic osmolyte chemotaxonomy can support green algal taxonomic designations as fundamental research.

• The Korean Journal of Physiology and Pharmacology
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• v.11 no.3
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• pp.135-138
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• 2007

Hypertonicity imposes a great deal of stress to cells since it causes rise in cellular ionic strength, which can be reduced by the accumulation of compatible osmolytes. TonEBP plays a central role in the cellular accumulation of compatible osmolytes via transcriptional stimulation of membrane transporters and aldose reductase. Alternatively spliced forms of TonEBP mRNA have previously been reported and two of them showed different transcriptional activity. In the present study, isoform-specific antibodies were produced to confirm the translation of the spliced mRNA to protein. TonEBP was immunoprecipitated by using anti-TonEBP antibody and then immunoblotted using anti-TonEBP or isoform specific antibodies to find out the expression profile of TonEBP isoforms in basal or stimulated condition. From these results, we conclude that all TonEBP isoforms are expressed in mammalian cells and their expression patterns are not same in every cells.

• Journal of Plant Biotechnology
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• v.7 no.1
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• pp.1-15
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• 2005

Salinity is one of the major limiting factors for agricultural productivity. In plants, accumulation of osmolytes plays a pivotal role in abiotic stress tolerance. Likewise, exclusion or compartmentation of $Na^+$ ions into vacuoles provides an efficient mechanism to avert deleterious effects of $Na^+$ in the cytosol. Both vacuolar and plasma membrane sodium transporters and $H^+-ATPases$ can provide the necessary ion homeostasis. A variety of crop plants were engineered with respect to the synthesis of osmoprotectants and ion-compartmentation, but there are other cellular pathways involved in the salinity responses that are still not completely explored. Genomics approaches are increasingly used to identify genes and pathway changes involved in salt-tolerance. The new knowledge may be used via guided genetic engineering of multiple genes to create crop plants with significantly increased productivity in saline soils. This review surveys how plants deal with high salt conditions and how salt tolerance can be improved by transgenic approaches.

• Journal of Microbiology and Biotechnology
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• v.27 no.9
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• pp.1681-1691
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• 2017

This study investigated the effect of proline addition on the salt tolerance of Tetragenococcus halophilus. Salt stress led to the accumulation of intracellular proline in T. halophilus. When 0.5 g/l proline was added to hyperhaline medium, the biomass increased 34.6% (12% NaCl) and 27.7% (18% NaCl) compared with the control (without proline addition), respectively. A metabolomic approach was employed to reveal the cellular metabolic responses and protective mechanisms of proline upon salt stress. The results showed that both the cellular membrane fatty acid composition and metabolite profiling responded by increasing unsaturated and cyclopropane fatty acid proportions, as well as accumulating some specific intracellular metabolites (environmental stress protector). Higher contents of intermediates involved in glycolysis, the tricarboxylic acid cycle, and the pentose phosphate pathway were observed in the cells supplemented with proline. In addition, addition of proline resulted in increased concentrations of many organic osmolytes, including glutamate, alanine, citrulline, N-acetyl-tryptophan, and mannitol, which may be beneficial for osmotic homeostasis. Taken together, results in this study suggested that proline plays a protective role in improving the salt tolerance of T. halophilus by regulating the related metabolic pathways.

• ALGAE
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• v.26 no.1
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• pp.21-32
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• 2011

Studies of the red algal genus Bostrychia over the last 15 years have made it a model system for many evolutionary processes within red algal species. The combination of newly developed, or first employed methods, in red algal species studies has made Bostrychia a pioneer genus in intraspecific studies. Bostrychia was the first genus in which a mitochondrial marker was used for intraspecific red algal phylogeny, and the first for which a 3-genome phylogeny was undertaken. The genus was the first red alga used to genetically show maternal plastid and mitochondria inheritance, and also to show correlation between cryptic species (genetically divergent intraspecific lineages) and reproductive incompatibility. The chemotaxonomic use, and physiological function of osmolytes, has also been extensively studied in Bostrychia. Our continuous studies of Bostrychia also highlight important aspects in algal species studies. Our worldwide sampling, and resampling in certain areas, show that intensive sampling is needed to accurately assess the genetic diversity and therefore phylogeographic history of algal species, with increased sampling altering evolutionary hypotheses. Our studies have also shown that long-term morphological character stability (stasis) and character convergence can only be correctly assessed with wide geographic sampling of morphological species. While reproductive incompatibility of divergent lineages supports the biological species nature of these lineages, reproductive incompatibility is also seen between isolates with little genetic divergence. It seems that reproductive incompatibility may evolve quickly in red algae and the unique early stages of fertilization (e.g., gametes covered by walls, active movement of spermatium nuclei to the distant egg nucleus), also well investigated in Bostrychia,. may be key to our understanding of this process.

• Journal of Bio-Environment Control
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• v.16 no.4
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• pp.303-308
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• 2007

An accumulation levels of osmolytes in chilling-tolerant and chilling-sensitive cultivar of Cucurbits against chilling stress were determined during chilling stress. Total soluble sugar contents in tolerant cultivar did not changes fur 10 days after chilling stress, but then slightly increased 20 days after chilling stress. In sensitive cultivar, it was increased rapidly in the beginning of chilling stress, and increased 3.4 times as much 20 days after chilling stress as compared with unstressed plants. Proline contents in tolerant cultivar was rapidly increased by the beginning of chilling stress, and then increased 26.6 times 20 days after chilling stress as compared with unstressed plants. In sensitive cultivar, it was increased 22.0 times 20 days after chilling stress as compared with unstressed plants. A levels of glycine betaine (GB) in tolerant cultivar increased 1.9 times as much during the 20 days of chilling stress. However, concentration of GB in sensitive cultivar did not change during the chilling stress. When plants were treated exogenous GB as a foliar spray, chilling tolerance was significantly enhanced in both cultivars. The foliar application of exogenous GB was induced chilling tolerance by accumulation of GB in the plant organs. However, it does not accumulate endogenous proline.

• Plant Biotechnology Reports
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• v.5 no.1
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• pp.71-77
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• 2011

Drought and salinity are the most important abiotic stresses that affect the normal growth and development of plants. Glycine betaine is one of the most important osmolytes present in higher plants that enable them to cope with environmental stresses through osmotic adjustment. In this study, a betaine aldehyde dehydrogenase (BADH) gene from spinach under the control of the stress-induced promoter rd29A from Arabidopsis thaliana was introduced into potato cultivar Gannongshu 2 by the Agrobacterium tumefaciens system. Putative transgenic plants were confirmed by Southern blot analysis. Northern hybridization analysis demonstrated that expression of BADH gene was induced by drought and NaCl stress in the transgenic potato plants. The BADH activity in the transgenic potato plants was between 10.8 and 11.7 U. There was a negative relationship (y = -2.2083x + 43.329, r = 0.9495) between BADH activity and the relative electrical conductivity of the transgenic potato plant leaves. Plant height increased by 0.4-0.9 cm and fresh weight per plant increased by 17-29% for the transgenic potato plants under NaCl and polyethylene glycol stresses compared with the control potato plants. These results indicated that the ability of transgenic plants to tolerate drought and salt was increased when their BADH activity was increased.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.52 no.4
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• pp.458-468
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• 2007

To tolerate environmentally adverse conditions such as cold, drought, and salinity, plants often synthesize and accumulate proline in cells as compatible osmolytes. ${\Delta}^1$-Pyrroline-5-carboxylate synthetase(P5CS) catalyzes the rate-limiting step of proline biosynthesis from glutamate. Two complete genes, MtP5CS1 and MtP5CS2, were isolated from the model legume Medicago truncatula by cDNA cloning and bacterial artificial chromosome library screening. Nucleotide sequence analysis showed that both genes consisted of 20 exons and 19 introns. Alignment of the predicted amino acid sequences revealed high similarities with P5CS proteins from other plant species. The two MtP5CS genes were expressed in response to high salt and low temperature treatments. Semi-quantitative reverse transcription-polymerase chain reaction showed that MtP5CS1 was expressed earlier than MtP5CS2, indicating differential regulation of the two genes. To evaluate the reverse genetic effects of nucleotide changes on MtP5CS function, a Targeting Induced Local Lesions in Genomes approach was taken. Three mutants each were isolated for MtP5CS1 and MtP5CS2, of which a P5CS2 nonsense mutant carrying a codon change from arginine to stop was expected to bring translation to premature termination. These provide a valuable genetic resource with which to determine the function of the P5CS genes in environmental stress responses of legume crops.