• Molecules and Cells
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• v.40 no.8
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• pp.577-586
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• 2017

Phytocystatins (PhyCYSs) are plant-specific proteinaceous inhibitors that are implicated in protein turnover and stress responses. Here, we characterized a PhyCYS from Arabidopsis thaliana, which was designated AtCYS5. RT-qPCR analysis showed that the expression of AtCYS5 in germinating seeds was induced by heat stress (HS) and exogenous abscisic acid (ABA) treatment. Analysis of the expression of the ${\beta}-glucuronidase$ reporter gene under the control of the AtCYS5 promoter showed that AtCYS5 expression during seed germination was induced by HS and ABA. Constitutive overexpression of AtCYS5 driven by the cauliflower mosaic virus 35S promoter led to enhanced HS tolerance in transgenic Arabidopsis, which was characterized by higher fresh weight and root length compared to wild-type (WT) and knockout (cys5) plants grown under HS conditions. The HS tolerance of AtCYS5-overexpressing transgenic plants was associated with increased insensitivity to exogenous ABA during both seed germination and post-germination compared to WT and cys5. Although no HS elements were identified in the 5'-flanking region of AtCYS5, canonical ABA-responsive elements (ABREs) were detected. AtCYS5 was upregulated in ABAtreated protoplasts transiently co-expressing this gene and genes encoding bZIP ABRE-binding factors (ABFs and AREB3). In the absence of ABA, ABF1 and ABF3 directly bound to the ABREs in the AtCYS5 promoter, which activated the transcription of this gene in the presence of ABA. These results suggest that an ABA-dependent pathway plays a positive role in the HS-responsive expression of AtCYS5 during seed germination and post-germination growth.

• BMB Reports
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• v.40 no.1
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• pp.107-112
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• 2007

To study the functioning of HSP70 in Escherichia coli, we selected NtHSP70-2 (AY372070) from among three genomic clones isolated in Nicotiana tabacum. Recombinant NtHSP70-2, containing a hexahistidine tag at the amino-terminus, was constructed, expressed in E. coli, and purified by $Ni^{2+}$ affinity chromatography and Q Sepharose Fast Flow anion exchange chromatography. The expressed fusion protein, $H_6NtHSP70$-2 (hexahistidine-tagged Nicotiana tabacum heat shock protein 70-2), maintained the stability of E. coli proteins up to 90$^{\circ}C$. Measuring the light scattering of luciferase (luc) revealed that NtHSP70-2 prevents the aggregation of luc without ATP during high-temperature stress. In a functional bioassay (1 h at 50$^{\circ}C$) for recombinant $H_6NtHSP70$-2, E. coli cells overexpressing $H_6NtHSP70$-2 survived about seven times longer than those lacking $H_6NtHSP70$-2. After 2 h at 50$^{\circ}C$, only the E. coli overexpressing $H_6NtHSP70$-2 survived under such conditions. Our NtHSP70-2 bioassays, as well as in vitro studies, strongly suggest that HSP70 confers thermo-tolerance to E. coli.

• Nuclear Engineering and Technology
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• v.53 no.2
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• pp.572-582
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• 2021

This study investigated the creep and creep crack growth (CCG) behavior of the base metal (BM), weld metal (WM), and heat affected zone (HAZ) in a Gr. 91 weldment, which was made by a shield metal arc weld process. A series of tensile, creep, and CCG tests were performed for the BM, WM, and HAZ at 550 ℃. Creep behavior of the BM, WM, and HAZ was analyzed in terms of various creep laws; Norton's power-law, Monkman-Grant relation and damage tolerance factor (λ), and their constants were determined. In addition, each CCGR law for the BM, WM, and HAZ was proposed and compared in terms of a C^*-fracture parameter. The WM and HAZ revealed faster creep rate, lower rupture ductility, and faster CCGRs than the BM, but they showed a similar behavior in the creep and CCG. The CCGRs obtained in the present study exhibited a marginal difference when compared with those of RCC-MRx of currently elevated design code in France. A creep crack path in the HAZ plane progressed towards a weak fine-grained HAZ adjacent to the BM.

• Journal of fish pathology
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• v.12 no.2
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• pp.89-99
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• 1999

New sixteen heat shock proteins (Hsps) and ten ethanol shock proteins were appeared on the analysis with SDS-PAGE when cultivation temperature for the Vibrio vulnifrcus ATCC 27562 strain was shifted-up to $42^{\circ}C$ from $30^{\circ}C$ for 20 mins and treated with of 6% ethanol for 10 mins, respectively. Even the induction of thermotolerance in V. vulnificus was coincided with the induction of Hsps if the pre-shock was adjusted to thermal temperature. Outer membrane proteins (OMPs) that were purified from the membrane of cells after heat shock showed more immunodominant pattern to the immunized rabbit anti-V. vulnificus O serum in enzyme-linked immunosorbent assay (ELISA). On the western immunoblot analysis it was confirmed that both 62 kDa IMP and 69 kDa OMP in the Hsps and 48 kDa IMP a major OMP in the ethanol shock proteins were reacted with rabbit anti-V. vulnificus O sera. Agglutination titer of the heat shocked V. vulnificus with rabbit anti-V. vulnificus O serum was higher than that of the untreated bacteria.

• The Korean Journal of Physiology and Pharmacology
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• v.11 no.6
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• pp.233-237
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• 2007

Tropical natives (TROP) are capable of tolerating tropical heat because of their long-term adaptation to tropical environments. When exposed to heat stress, these natives tend to respond with lower sweat output, which is generally thought to be the result of heat acclimatization. The main objective of this study was to clarify central mechanisms inherent to suppressed thermal sweating in tropical natives (Malaysians) by comparing their sweating responses to those of temperate native (TEMP) (Koreans). This experiment was conducted in a thermoneutral climatic chamber ($24{\pm}0.5^{\circ}C,\;40{\pm}3%$ relative humidity). Heat loads were applied to each subject by the immersion of their lower legs in a hot water bath ($43^{\circ}C$ for 30 min). Sweat onset-time and sweat volume were compared between TROP and TEMP. The sweat onset-times on four selected points on the body ranged from 10.25 to 13.47 min in TEMP subjects, and from 16.24 to 17.83 min in TROP subjects (p<0.001). The local sweat volumes at the same sites ranged from 4.30 to $9.74 mg/cm^2$ in TEMP subjects, and from between 1.80 to $4.40mg/cm^2$ in TROP subjects (p<0.001). These results demonstrated a significant difference between TROP and TEMP subjects with regard to the manner in which they regulate their body temperatures when exposed to heat loads, and verified that long-term thermal adaptation blunts sweating sensitivities.

• Journal of Microbiology and Biotechnology
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• v.20 no.6
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• pp.974-977
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• 2010

Cyclophilins contain the conserved activity of cis-trans peptidyl-prolyl isomerase, which is implicated in protein folding, and function as molecular chaperones. When the yeast cyclophilin A gene (cpr1) was subcloned into the prokaryotic expression vector pKM260, it was found that the expression of Cpr1 drastically increased the cell viability of E. coli BL21 when under abiotic stress conditions, as in the presence of cadmium, copper, hydrogen peroxide, heat, and SDS. Therefore, this study illustrates the importance of Cpr1 as a molecular chaperone that can improve the cellular stress responses when E. coli cells are exposed to adverse conditions, while also demonstrating its potential to increase the stability of E. coli strains utilized for the production of recombinant proteins.

• Journal of Microbiology and Biotechnology
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• v.25 no.10
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• pp.1660-1669
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• 2015

The present study describes the gene cloning, overexpression and characterization of a novel nitrilase from hyperthermophilic bacterium Thermotoga maritima MSB8. The nitrilase gene consisted of 804 base pairs, encoding a protein of 268 amino acid residues with a molecular mass of 30.07 kDa after SDS-PAGE analysis. The optimal temperature and pH of the purified enzyme were 45℃ and 7.5, respectively. The enzyme demonstrated good temperature tolerance, with 40% residual activity after 60 min of heat treatment at 75℃. The kinetic constants V_max and K_m of this nitrilase toward 3-cyanopyridine were 3.12 μmol/min/mg and 7.63 mM, respectively. Furthermore, this novel nitrilase exhibited a broad spectrum toward the hydrolysis of the aliphatic nitriles among the tested substrates, and particularly was specific to aliphatic dinitriles like succinonitrile, which was distinguished from most nitrilases ever reported. The catalytic efficiency k_cat/K_m was 0.44 /mM/s toward succinonitrile. This distinct characteristic might enable this nitrilase to be a potential candidate for industrial applications for biosynthesis of carboxylic acid.

• Journal of Microbiology and Biotechnology
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• v.23 no.9
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• pp.1253-1259
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• 2013

The influences of glucose concentration, initial medium acidity (pH), and temperature on the growth and ethanol production of Saccharomyces cerevisiae NK28, which was isolated from kiwi fruit, were examined in shake flask cultures. The optimal glucose concentration, initial medium pH, and temperature for ethanol production were 200 g/l, pH 6.0, and $35^{\circ}C$, respectively. Under this growth condition, S. cerevisiae NK28 produced $98.9{\pm}5.67$ g/l ethanol in 24 h with a volumetric ethanol production rate of $4.12{\pm}0.24g/l{\cdot}h$. S. cerevisiae NK28 was more tolerant to heat and ethanol than laboratory strain S. cerevisiae BY4742, and its tolerance to ethanol and fermentation inhibitors was comparable to that of an ethanologen, S. cerevisiae D5A.

• Journal of Pharmaceutical Investigation
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• v.30 no.1
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• pp.47-50
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• 2000

A new technique has been developed for the preparation of Lactobacillus microcapsules to enhance the stability against high temperature, humidity, gastric acid and bile acid. Employing fluidized bed coating, primary sub-coating was processed in non-organic solvent system, so that Lactobacillus did not directly contact with organic solvent. Secondary enteric-coating was processed in organic solvent with low temperature $(below\;33^{\circ}C)$ technique, which minimized the heat labilability of Lactobacillus. Survival rate of Lactobacillus within microcapsule was not less than 95% and acid tolerance was above 30% in the artificial gastric acid. Further more it was dissolved in the artificial intestine juice within 2-3 hr. Average size of Lactobacillus microcapsules was $450\;{\mu}m$(25-50 mesh) and its viability was above 90% in the direct tableting.

• Microbiology and Biotechnology Letters
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• v.44 no.2
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• pp.201-207
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• 2016

The aim of this study was to investigate the potential of lactic acid bacteria (LAB) strains as probiotics. Two strains were isolated from healthy chicken cecum and their acid and bile tolerance, residual organic acids, antibacterial activity against pathogenic bacteria, and immunomodulation activity were measured. Identification of the isolated strains was performed using the API 50CHL system and phylogenetic analysis using 16S rDNA sequencing. The isolates were determined to be Lactobacillus sakei strains. The acid tolerance of strains L2 and L8 was high enough that 75% of the inoculum survived in pH 2 for 2 h. The bile tolerance of both strains was observed at a 1% Oxgall concentration in MRS broth. The production of organic acids (lactic acid and acetic acid) and pH changes during growth were monitored and the maximum concentrations were obtained after 48 h of incubation. Culture supernatants of the two LAB strains showed strong antibacterial activity against pathogenic bacteria. The heat-killed LAB cells also induced high levels of immune cell proliferation compared with the control, and stimulated IL-6 and TNF-α production in mouse macrophages. Therefore, L. sakei strains L2 and L8 can be considered suitable probiotic bacteria.