• The Korean Journal of Physiology
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• v.30 no.2
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• pp.197-208
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• 1996

Endosomes lower their internal pH by an ATP-driven proton pump, which is critical to dissociation of many receptor-ligand complexes, the first step in the intracellular sorting of internalized receptors and ligands. Endosomes are known to exhibit n great range of pH values that can vary between 5.0 and 7.0 within a single cell although the factors that regulate endosomal pH remain uncertain. To evaluate the morphological and topological differences of endosomes in the different stages, confocal microscopy was used. The early endosomes labeled with fluorescein isothiocyanate-dextran for 10 min at $37^{\circ}C$ were identifiable at the peripheral and tubule-vesicular endosome compartment. In contrast, the late endosomes formed by 10 min pulse and 20 min trace were located deeper in the cytoplasm and showed more vesicular features than early endosomes. For the purpose of determining whether ATP-dependent acidification was heterogeneous and whether the differences in acidification were attributed to differences in the activity of $Na^{+}-K^{+}$-ATPase and/or $Cl^{-}$ channel, endocytic compartments were fractionated into subpopulation using percoll gradient and measured ATP-dependent acidification. While all fractions exhibited ATP-dependent acidification activity, both the initial rate of acidification and extent of proton translocation were lower in early endosomes and gradually increased in late endosomes. Phosphorylation by PKA and ATP enhanced ATP-dependent acidification in both early and late endosomes, hut there was no difference in the degree of enhancement by phosphorylation between two subpopulations. When ATP-dependent acidification was determined in the presence or absence of vanadate ($Na_{3}VO_{4}$) or ouabain, only early endosomes exhibited the vanadate or ouabain dependent stimulation of acidification activity, suggesting the inhibition of $Na^{+}-K^{+}$-ATPase. Therefore, it seems probable that the inhibition of early endosome acidification by $Na^{+}-K^{+}$-ATPase observed in vitro at least in part plays a physiological role in controlling the acidification of early endosomes in vivo.

• Microbiology and Biotechnology Letters
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• v.34 no.3
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• pp.221-227
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• 2006

BSCX1 was an antimicrobial peptide produced by Bacillus subtilis cx1. Attempts were made to determine the location of inducing factor in the bacteriocin-sensitive cell affecting bacteriocin BSCX1 production. Mixed culture of the bacteriocin producer strain B. subtilis cx1 and its sensitive strain B. subtilis ATCC6633, increased production of bacteriocin BSCX1. The result suggested the presence of a bacteriocin inducing factor in the sensitive strain. The inducing factor was localized in the cell debris and intracellular fraction of B. subtilis ATCC6633. Bacteriocin BSCX1 inducing factor was found to be highly stable in the pH range 2.5-9.5, but inactivated within 3h over $50^{\circ}C$, and treatment with proteinase K destroyed its inducing activity, this result suggested that the inducing factor should be a proteinaceous nature.

• Applied Biological Chemistry
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• v.17 no.2
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• pp.93-116
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• 1974

A potent intracellular-lipid-producing yeast, Rhodotorula glutinis var. glutinis SW-17, was screened out from a variety of arable soils, compost heaps, and fodders, and two strains of excellent extracellular-lipid-producing yeasts, Rhodotorula glutinis var. glutinis SW-5 and Rhodotorula graminis SW-54, were screened out from the surface of many species of leaves. And then the intra- and extra-cellular lipid productions by those Rhodotorula yeasts were studied. The results were as follows: 1. During the shaking culture of 8 days at $24^{\circ}C$, both the intra- and extra-cellular lipid accumulation started almost at the stationary phase of growth, when the nitrogen source in the medium was a little more than half used up. The intracellular lipid production by Rhodotorula glutinis var. glutinis SW-17 reached 58.42% (w/w) of dried yeast, and the extracellular lipid production by Rhodotorula graminis SW-54 amounted to 2.62g per liter of the medium. 2. After the carbon and nitrogen sources in the medium were almost consumed, if the yeasts were shake-cultured further in a state of starvation, the yeast cells re-utilized the already produced intra- and extra-cellular lipids and the lipids completely disappeared in the medium in about 90 days. 3. The relative concentration of carbon and nitrogen sources in the media greatly influenced both the intra- and extra-cellular lipid production. When the nitrogen source in the medium was almost used up for the growth of yeast, and excess carbon sources were still available, the lipid production vigorously proceeded. As long as the nitrogen source concentration in the medium was high, the lipid production was greatly suppressed. 4. The optimum pH for both the intra- and extra-cellular lipid production by those yeasts was pH 5.0-6.0. 5. The fatty acid components of the intracellular lipid of Rhodotorula glutinis var. glutinis SW-17 were myristic, palmitic, palmitoleic, stearic, oleic, linoleic, and linolenic acids. The largest components of the fatty acids were palmitic acid equivalent to 30-45% of the whole fatty acids and oleic acid equivalent to 35-50%. 6. The fatty acid components of the extracellular lipid of Rhodotorula glutinis var. glutinis SW-5 and Rhodotorula graminis SW-54 were myristic, palmitic, stearic, oleic, linoleic, linolenic, 3-D-hydroxypalmitic, and 3-D-hydroxystearic acids. The largest components of the fatty acids were 3-D-hydroxypalmitic acid equivalent to 22-25% of the acids and 3-D-hydroxystearic acid equivalent to 13-17%. 7. The polyol component of the intracellular lipids was only glycerol, whereas the polyols of extracellular lipids were glycerol, mannitol, xylitol and arabitol.

• Journal of Microbiology and Biotechnology
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• v.30 no.7
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• pp.996-1004
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• 2020

Various genetically engineered microorganisms have been developed for the removal of heavy metal contaminants. Metal biosorption by whole-cell biosorbents can be enhanced by overproduction of metal-binding proteins/peptides in the cytoplasm or on the cell surface. However, few studies have compared the biosorption capacity of whole cells expressing intracellular or surface-displayed metal-adsorbing proteins. In this study, several constructs were prepared for expressing intracellular and surface-displayed Ochrobactrum tritici 5bvl1 ChrB in Escherichia coli BL21(DE3) cells. E. coli cells expressing surface-displayed ChrB removed more Cr(VI) from aqueous solutions than cells with cytoplasmic ChrB under the same conditions. However, intracellular ChrB was less susceptible to variation in extracellular conditions (pH and ionic strength), and more effectively removed Cr(VI) from industrial wastewater than the surface-displayed ChrB at low pH (<3). An adsorption-desorption experiment demonstrated that compared with intracellular accumulation, cell-surface adsorption is reversible, which allows easy desorption of the adsorbed metal ions and regeneration of the bioadsorbent. In addition, an intrinsic ChrB protein fluorescence assay suggested that pH and salinity may influence the Cr(VI) adsorption capacity of ChrB-expressing E. coli cells by modulating the ChrB protein conformation. Although the characteristics of ChrB may not be universal for all metal-binding proteins, our study provides new insights into different engineering strategies for whole-cell biosorbents for removing heavy metals from industrial effluents.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.2
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• pp.653-664
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• 2012

Objective: This study assessed anti-inflammatory and antioxidant activities of $E.$ $foetidum$ leaf extract on LPS-activated murine macrophages. Methods: RAW264.7 cells were pretreated with or without $E.$ $foetidum$ extract for 1 h prior to incubation with LPS for 24 h. Anti-inflammatory activity was evaluated with reference to iNOS, COX-2, TNF-${\alpha}$ and IL-6 gene expression. In addition, NO and intracellular ROS generation were determined by Griess method and fluorescence intensity and activation of MAPKs and $I{\kappa}B$ by Western blotting. Results: Prior treatment with $E.$ $foetidum$ leaf extract inhibited elevation of IL-6, TNF-${\alpha}$, iNOS and COX-2, together with their cognate mRNAs in a dose-dependent manner. NO and intracellular ROS contents were similarly reduced. These effects were due to inhibition of LPS-induced phosphorylation of JNK and p38 as well as $I{\kappa}B$. $E.$ $foetidum$ ethanol extract were shown to contain lutein, ${\beta}$-carotene, chlorogenic acid, kaempferol and caffeic acid, compounds known to exert these bioactive properties. Conclusions: $E.$ $foetidum$ leaf extract possesses suppressive effects against pro-inflammatory mediators. Thus, $E.$ $foetidum$ has a high potential to be used as a food supplement to reduce risk of cancer associated with inflammation.

• Journal of The Korean Society of Integrative Medicine
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• v.12 no.1
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• pp.1-10
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• 2024

Purpose: Lycopene is abundantly contained in Tomatoes and is known for diverse biological activities such as antioxidant, anti-inflammatory, and anticancer effects. In this study, the antioxidative potential of lycopene was investigated through the induction of hemeoxygenase (HO)-1 by nuclear factor-erythroid 2 p45-related factor2 (Nrf2) and upstream signaling molecules, mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K)/Aktin RAW 264.7 cells. Methods: The antioxidative potential of lycopene against oxidative stress and its molecular mechanisms were determined by the cell viability assay, intracellular reactive oxygen species (ROS) formation assay, and Western blot analysis in RAW 264.7 cells. Results: Lycopene treatment significantly attenuated tert-butyl hydroperoxide (t-BHP) induced intracellular ROS formation in a dose-dependent manner without any cytotoxicity. In addition, 50 µM of lycopene for 6 h treatment induced potent HO-1 expression and its transcription factor, Nrf2. MAPK and PI3K/Aktwere also analyzed due to their critical roles in the regulation of cellular redox homeostasis against oxidative damage. As a result, phosphorylation of extracellular regulated kinase (ERK) was significantly induced by lycopene treatment while the activated status of c-Jun NH2-terminal kinase (JNK), p38, and Akt, were not given any effect. To confirm the antioxidative mechanism of HO-1 mediated by ERK activation, each selective inhibitor was employed in a protection assay, in which oxidative damage occurred by t-BHP. Lycopene, SnPP, and CoPP treatments reflected accelerated HO-1 expression could be a protective role against oxidative damage-initiated cell death. A selective inhibitor for ERK significantly inhibited the lycopene-induced cytoprotective effect but selective inhibitors for other signaling molecules did not attenuate the rate of t-BHP-induced cell death. Conclusion: In conclusion, lycopene potently scavenged intracellular ROS formation and enhanced the HO-1 mediated antioxidative potential through the modulation of Nrf2, MAPK signaling pathway in RAW 264.7 cells.

• Journal of Life Science
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• v.30 no.7
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• pp.581-591
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• 2020

This study investigated the probiotic properties and physiological activities of Korean fermented foods such as sikhae, young radish kimchi, and bean-curd dregs. Among the isolated lactic acid bacteria, Pediococcus inopinatus BZ4, Lactobacillus plantarum SH1, Lactobacillus brevis SH14, Pediococcus pentosaceus YMT1, and Leuconostoc mesenteroides YMT6 demonstrated a greater than 60% survival rate at pH 2.5, along with an excellent survival rate even at 0.3% bile acid. These five bacteria showed strong flocculation ability in autoaggregation and coaggregation tests, indirectly clustering useful micro-organisms and inhibiting the attachment of pathogenic bacteria. In a cell surface hydrophobicity test, these bacteria showed adhesion to three solvents (ethyl acetate, chloroform, and xylene) and high hydrophobicity, thereby indicating excellent indirect cell adhesion to intestinal cells. The cell-free supernatants and intracellular extracts of the five lactic acid bacteria showed antioxidative activity in the form of 2,2-Diphenyl-1-picrylhydrazyl and 2,2'-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging ability and lipid peroxidation inhibition. Antimicrobial activities were also observed in four pathogenic bacteria, namely E. coli KCTC 2571, H. pylori HPKCTC B0150, L. monocytogenes KCTC 13064, and S. aureus KCTC 1916. These results demonstrate that these five lactic acid bacteria could be used as probiotics with antioxidant and antimicrobial properties.

• The Korean Journal of Pharmacology
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• v.32 no.1
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• pp.67-74
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• 1996

Cholecystokinin octapeptide (CCK-8), acetylcholine (ACh) and KCl caused a dose dependent contraction in muscle cells enzymatically digested from cat gallbladder. Maximal contraction was obtained at concentration of $10^{-9}M$ for CCK-8, $10^{-5}M$ for ACh and 20mM for KCl. CCK-8 induced contraction was unaffected in calcium free physiological salt solution (PSS) and was completely blocked by strontium substitution for calcium (p<0.001). In contrast, KCl evoked contraction was blocked in calcium free PSS (p<0.01) but was unaffected by strontium replacement of calcium. The contraction elicited by ACh was only slightly reduced in calcium free PSS (p<0.05) and was unaltered by strontium. Muscle cells permeabilized with saponin contracted in response to inositol 1,4.5-trisphosphate $(IP_3)$ and CCK-8. The contraction was blocked by the calmodulin antagonist CGS 9343B (p<0.001), whereas heparin completely blocked the effect of $IP_3$ (p<0.001). The protein kinase C (PKC) antagonist H7 had no effect on either agonist. We conclude that CCK-8 induced gallbladder muscle contraction is mediated by $IP_3$ dependent intracellular calcium release from intracellular stores and a calmodulin dependent pathway; ACh may utilize both extracellular and intracellular calcium. KCl causes muscle contracrion through influx of extracellular calcium and a calmodulin independent machanism.

• Korean Journal of Microbiology
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• v.43 no.1
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• pp.59-65
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• 2007

The optimal conditions for Monascus pigments production of Monascus sp. KM 1001, pigment overproducing mutant, in submerged culture was investigated. The optimal medium for the production of pigment from KM 1001 mutant is determined to be composed of 4% rice powder, 0.15% Bacto-peptone, 0.1% glycine, 0.01% $FeSO_{4}{\cdot}7H_{2}O,\;0.1%\;MgSO_{4}{\cdot}7H_{2}O,\;0.25%\;KH_{2}PO_{4},\;pH4.5$. On optimal conditions,10.0 g/L of the cell mass was obtained at $30^{\circ}C$ for 5 days. Yellow, orange and red pigment of Monascus sp. KM 1001 were produced 3.25 units, 1.59 units and 0.88 units in extracellular part, and 84.96 units, 78.84 units and 91.80 units in intracellular part, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.1
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• pp.123-131
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• 2020

In this study, we investigated the protective effects of a Neutrase enzymatic hydrolysate derived from Korea pen shell Atrina pectinata (APN) against hydrogen peroxide (H₂O₂)-induced oxidative damage in hepatocytes. First, we confirmed that APN has antioxidant activities by scavenging 2,2-azino-bis (3-ethylbenzthiazoline)-6-sulfonic acid radical (ABTS⁺) and H₂O₂ and increasing oxygen radical absorbance capacity (ORAC) value. Also, the treatment of APN increased the cell viability by reducing the intracellular reactive oxygen species (ROS) production in H₂O₂-stimulated hepatocytes. In addition, APN decreased the sub-G₁ DNA contents and the apoptotic body formation increased by H₂O₂ stimulation. Moreover, APN modulated the protein expression of apoptosis related molecules (Bcl-2, Bax and p53) by suppressing the activation of nuclear factor NFkB and ERK/p38 signaling in H₂O₂-stimulated hepatocytes. Furthermore, APN led to the activation of Nrf2/HO-1signaling known as antioxidant systems. These results suggest APN protects hepatocytes against oxidative damages caused by H₂O₂ stimulation.