• Microbiology and Biotechnology Letters
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• v.43 no.2
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• pp.91-96
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• 2015

Prions are proteinaceous infectious particles that cause neurodegenerative diseases, such as scrapie in sheep, bovine spongiform encephalopathy in cattle and Creutzfeldt-Jakob disease (CJD) in humans. Although the detailed process, regarding the abnormal conversion of prion proteins (PrP), remains to be fully elucidated, a number of environmental factors appear to affect the formation of misfolded PrP, termed PrP^Sc. Because oceanic algae contain mycosporine-like amino acids (MAAs), which exhibit cellular defensive activities under a variety of stress conditions, we investigated the level of PrP^Sc in prion-infected neuroblastoma cells using mycosporine-glycine, porphyra-334 and shinorine. When judged by the level of protease-resistant PrP^Sc in western blots, porphyra-334 and shinorine increased the level of PrP^Sc in cells, but mycosporine-glycine did not. The current results indicate that the MAAs tested in this study enhance the formation of PrP^Sc.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.06a
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• pp.413-416
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• 1998

In this paper we first show that uniform PR systems and half independent PR systems have same dynamics, and then an important property of this two kinds of systems is derived. The most important property of uniform PR systems is that they have the ability of classifying m-dimensional problabilistic vector into in classes. The significance of studying the dynamics of uniform PR systems are tried from the beginning with a uniform PR system.

• Rapid Communication in Photoscience
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• v.2 no.2
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• pp.52-55
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• 2013

Proteorhodopsin (PR) is a photoinduced proton pump found abundantly in ocean and fresh water habitat, and has an important role in photoenergy conversion to bioenergy in the living cells. Numerous sequences that encode PR protein variants were discovered by environmental genome sequencing and they indicated the high sequence similarity. A new-type of PR (YS-PR) which had been discovered from the surface of Yellow Sea was found to have only 5 amino acid differences from the previously known green-light absorbing PR (GPR) protein, but showed different photochemical properties. This YS-PR showed a 10 nm red-shifted absorption maximum, when compared with GPR. It also showed slower photocycling rate than GPR. However, the photoconversion rate of YS-PR was fast enough to pump protons. Four different amino acids out of 5 were similar to Blue-light absorbing PR (BPR), suggesting that those residues might be responsible for the observed spectral and photoconverting properties.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.12
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• pp.1635-1640
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• 2004

Two experiments were conducted to evaluate developmental gene expression of antimicrobial peptide PR-39 and effect of zinc oxide on gene regulation of PR-39 in piglets using semi-quantitative RT-PCR analysis. In experiment 1, fifteen female Tai-Hu pigs (a local breed in China) in five groups, each of three pigs at 1, 14, 28, 42 and 56 days of age were used to determine effect of age and weaning on mRNA expression of PR-39. In experiment 2, nine groups of pigs (total seventy-two female 36 days-age weanling Tai-Hu piglets) were assigned to three treatments (${ZnO}_0$, ${ZnO}_{100}$ and ${ZnO}_{3000}$). The feeding experimental period lasted 15 days. After feeding experiment, nine pigs with three animals in each treatment were chosen to determine the effect of ZnO on PR-39 mRNA expression of pigs. The results showed that PR-39 mRNA levels increased steadily in postnatal day 1-28 (preweaning), and weaning significantly decreased PR-39 mRNA expression of piglets (p<0.05). ${ZnO}_{3000}$ (3,000 mg zinc/kg diet) significantly increased PR-39 mRNA expression (p<0.05) when piglets were feed ${ZnO}_{3000}$ diet for 15 days. ${ZnO}_{100}$ (100 mg zinc/kg diet) also increased PR-39 gene expression, but the result was not statistically significant (p>0.05). The result was in accordance with the effect of ${ZnO}_{3000}$ and ${ZnO}_{100}$ on weight gain of piglets and prevention of diarrhea.

• Molecules and Cells
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• v.27 no.6
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• pp.673-680
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• 2009

Conversion of the normal soluble form of prion protein, PrP ($PrP^C$), to proteinase K-resistant form ($PrP^{Sc}$) is a common molecular etiology of prion diseases. Proteinase K-resistance is attributed to a drastic conformational change from ${\alpha}$-helix to ${\beta}$-sheet and subsequent fibril formation. Compelling evidence suggests that membranes play a role in the conformational conversion of PrP. However, biophysical mechanisms underlying the conformational changes of PrP and membrane binding are still elusive. Recently, we demonstrated that the putative transmembrane domain (TMD; residues 111-135) of Syrian hamster PrP penetrates into the membrane upon the reduction of the conserved disulfide bond of PrP. To understand the mechanism underlying the membrane insertion of the TMD, here we explored changes in conformation and membrane binding abilities of PrP using wild type and cysteine-free mutant. We show that the reduction of the disulfide bond of PrP removes motional restriction of the TMD, which might, in turn, expose the TMD into solvent. The released TMD then penetrates into the membrane. We suggest that the disulfide bond regulates the membrane binding mode of PrP by controlling the motional freedom of the TMD.

• Mycobiology
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• v.50 no.6
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• pp.457-466
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• 2022

Epicoccum nigrum is a saprophytic or endophytic fungus that is found worldwide. Because of the antagonist effects of E. nigrum on many plant pathogens, current studies on E. nigrum have focused on the development of biological control agents and the utilization of its various metabolites. In this study, E. nigrum was collected from a wheat field, and its genetic diversity was analyzed. Phylogenetic analyses identified 63 isolates of E. nigrum divided into seven groups, indicating a wide genetic diversity. Isolates antagonized the wheat pathogen Fusarium graminearum, and reduced disease symptoms caused by F. graminearum in wheat coleoptiles. Moreover, pretreatment of wheat coleoptiles with E. nigrum induced the upregulation of pathogen-related (PR) genes, PR1, PR2, PR3, PR5, PR9, and PR10 in wheat coleoptiles responding to F. graminearum invasion. Overall, this study indicates that E. nigrum isolates can be used as biological pathogen inhibitors applied in wheat fields.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.1
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• pp.68-73
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• 2024

In this study, the praseodymium-doped yttrium phosphate (YPO₄:Pr³⁺) powder, which is well known for its high luminescent efficiency, and long life in the UV range, was synthesized with various content ratios of Pr₆O₁₁ and calcination temperature. Crystal structure and luminescent properties of various phosphor powders based on different concentrations and calcination conditions were characterized by XRD (X-Ray Diffraction) and PL (photoluminescence) spectrometers. From the XRD analysis, the structure of YPO₄:Pr³⁺ which is calcinated at 1,200℃ was stable tetragonal phase and crystal size was calculated about 25 nm by Scherrer equation. PL emission of YPO₄:Pr³⁺ with a different content ratio of Pr₆O₁₁ by excitation λ_exc=250 nm shows that 0.75 mol% phosphor powder has maximum PL intensity and PL decreases with the increase of the ratio of Pr₆O₁₁ up to 1.25 mol% which is caused by changes of crystallinity of phosphor powders. With increasing dopant ratio, photo-luminescence Emission decreases due to Concentration quenching, which is commonly observed in phosphors. Currently, 0.75 mol% is considered the optimal doping concentration. A hybrid ultraviolet-emitting device incorporating YPO₄:Pr³⁺ fluorescent material with plasma discharge was fabricated to enhance UV germicidal effects while minimizing ozone generation. UV emission from the plasma discharge device was shown at about 200 nm and 350 nm which caused additional emission of the regions of 250 nm, 315 nm, and 370 nm from the YPO₄:Pr³⁺ phosphor.

• Journal of Life Science
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• v.25 no.1
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• pp.37-43
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• 2015

We have investigated the effects of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC), indole-3-acetic acid (IAA) and methyl jasmonate (MeJA) on the development of aerenchyma in the primary root of maize (Zea mays). Because plant hormones affected the longitudinal organization of the primary root, we need an indicator to direct the positions for comparison between control and hormone-treated roots. Therefore, the zones of the maize primary root were categorized as PR25, PR50 and PR75, where each value indicates the relative position between the root tip (PR0) and the base (PR100). Aerenchyma was not observed at PR25 and PR50 and rarely found at PR75 in the cortex of control roots. The aerenchymal area at PR75 increased in the presence of the ethylene precursor ACC or a natural auxin IAA. On the other hand, MeJA differentially acted on non-submerged and submerged roots. Exogenously applied MeJA suppressed the aerenchyma formation in non-submerged roots. When the primary root was submerged, aerenchymal area expanded prominently. The submergence-induced aerenchyma formation was amplified with MeJA. Lateral root primordia have been known to inhibit aerenchymal death of surrounding cells. All the three hormones stimulating aerenchyma formation as described above did not restore the inhibition caused by lateral root primordia, suggesting that the inhibitory step regulated by lateral root primordia can be located after hormonal signaling steps.

• Bulletin of the Korean Chemical Society
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• v.25 no.1
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• pp.90-96
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• 2004

The conformations of dicyclopropyl, isopropyl cyclopropyl, and diisopropylcarbenes were optimized using density functional theory (B3LYP/6-31G(d)). We showed that the optimized geometries of carbenes with cyclopropyl groups are fully in accord with those expected for bisected W-shaped conformations, in which the effective hyperconjugation of a cyclopropyl group with singlet carbene can occur. The stabilization energies were evaluated at the B3LYP/6-311+G(3df, 2p)//B3LYP/6-31G(d) + ZPE level using an isodesmic equation. The relative stability of carbenes is in the order $(c-Pr)_2$C: > (i-Pr)(c-Pr)C: > $(i-Pr)_2$C:, and a cyclopropyl group stabilizes carbene more than an isopropyl group by nearly 9 kcal/mol. Energies for the decomposition of diazo compounds to carbenes increase in the order $(c-Pr)_2$ < (i-Pr)(c-Pr) < $(i-Pr)_2$ by ~9 kcal/mol each. From a singlettriplet energy gap ($E_{ST}$) calculation, the singlet level is lower than the triplet level and the $E_{ST}$ shows a trend similar to the stabilization energy calculations. For comparison, the optimized geometries and stabilization energies for the corresponding carbocations were also studied at the same level of calculation. The greater changes in geometries and the higher stabilization energies for carbocations compared to carbenes can explain the greater hyperconjugation effect.

• Korean Journal of Food Science and Technology
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• v.34 no.4
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• pp.710-718
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• 2002

It is reported that Pueraria Radix contains phtoestrogens whereas flower, and bud of Pueraria lobata Ohwi were not known. In the present study, we determined the amount of phytoestrogen in each portion of P. lobata Ohwi and carried out therapeutic effects of osteoporosis. The amounts of genistein, daidzein, and formononetin in Pueraria Radix (PR), Pueraria Flos (PF), and young Pueratia Folium (PL) were quantitated using a HPLC system. Proliferation of osteoblast and growth inhibitory effect on osteoclast were measured in order to screen their effects on osteoporosis. Proliferation of osteoblast-like cells (Saos-2) was analyzed by both MTT methods and alkaline phosphatase (ALP) assays. Growth inhibitory effect on osteoclast was also detected as Tartrate resistant acid phosphatase (TRAP) assay. Ovariectomized rat as an in vivo animal model was selected and administrations of PR were 1 g/kg/day (PR-1) and 5 g/kg/day (PR-5) for 9 weeks, respectively. Trabecular bone areas (TBAs) of tibia and lumbar were analyzed usibg histomorphological methods. Results show that PR contains the highest level of daidzein ($10435{\pm}2143\;mg/kg$ of dried herb) and stimulated ALP activity, approximately 160% of the control. Growth inhibitory effect on osteoclast by both PR and daidzein were almost identical with control although $IC_{50}$ of genistein was $5.81{\times}10^{-7}$ M. Increases in body weight of OVX rats were suppressed by administration of PR but wet weights of uterus in PR-5 group were increased (p<0.05). Plasma ALP and HDL-cholesterol levels were decreased following ages (p<0.01), and LDL-cholesterol level was also decreased in PR-5 group at 20 week of age (p<0.01). TBAs of tibia and lumbar in PR-1 and PR-5 groups were higher than those of the control although the values were less than those of the sham group (each p<0.01) In conclusion, administrations of PR prevented loss of TBAs of tibia and lumber in OVX rats, while PL and PF did not (p<0.01).