Publications by authors named "Min Kyu Kim"

243 Publications

Optimal Treatment of 6-Dimethylaminopurine Enhances the In Vivo Development of Canine Embryos by Rapid Initiation of DNA Synthesis.

Int J Mol Sci 2021 Jul 20;22(14). Epub 2021 Jul 20.

Division of Animal & Dairy Science, College of Agriculture and Life Science, Chungnam National University, Daejeon 34134, Korea.

Artificial activation of oocytes is an important step for successful parthenogenesis and somatic cell nuclear transfer (SCNT). Here, we investigated the initiation of DNA synthesis and in vivo development of canine PA embryos and cloned embryos produced by treatment with 1.9 mM 6-dimethylaminopurine (6-DMAP) for different lengths of time. For experiments, oocytes for parthenogenesis and SCNT oocytes were cultured for 4 min in 10 μM calcium ionophore, and then divided into 2 groups: (1) culture for 2 h in 6-DMAP (DMAP-2h group); (2) culture for 4 h in DMAP (DMAP-4h group). DNA synthesis was clearly detected in all parthenogenetic (PA) embryos and cloned embryos incorporated BrdU 4 h after activation in DMAP-2h and DMAP-4h groups. In vivo development of canine parthenogenetic fetuses was observed after embryo transfer and the implantation rates of PA embryos in DMAP-2h were 34%, which was significantly higher than those in DMAP-4h (6.5%, < 0.05). However, in SCNT, there was no significant difference in pregnancy rate (DMAP-2h: 41.6% vs. DMAP-4h: 33.3%) and implantation rates (DMAP-2h: 4.94% vs. DMAP-4h: 3.19%) between DMAP-2h and DMAP-4h. In conclusion, the use of DMAP-2h for canine oocyte activation may be ideal for the in vivo development of PA zygotes, but it was not more effective in in vivo development of canine reconstructed SCNT oocytes. The present study demonstrated that DMAP-2h treatment on activation of canine parthenogenesis and SCNT could effectively induce the onset of DNA synthesis during the first cell cycle.
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http://dx.doi.org/10.3390/ijms22147757DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8303139PMC
July 2021

Hymenobacter taeanensis sp. nov., radiation resistant bacterium isolated from coastal sand dune.

Antonie Van Leeuwenhoek 2021 Jul 22. Epub 2021 Jul 22.

Radiation Research Division, Korea Atomic Energy Research Institute, Jeongeup, 56212, Republic of Korea.

An aerobic, Gram-stain-negative, non-motile, non-spore-forming, rod-shaped, and light pink-colored bacterial strain, designated TS19, was isolated from a sand sample obtained from a coastal sand dune after exposure to 3 kGy of gamma radiation. Phylogenetic analysis based on the 16S rRNA gene sequences revealed that the isolate was a member of the genus Hymenobacter and was most closely related to H. wooponensis WM78 (98.3% similarity). Strain TS19 and H. wooponensis showed resistance to gamma radiation with D values (i.e., the dose required to reduce the bacterial population by tenfold) of 7.3 kGy and 3.5 kGy, respectively. The genome of strain TS19 consists of one contig with 4,879,662 bp and has a G + C content of 56.2%. The genome contains 3,955 protein coding sequences, 44 tRNAs, and 12 rRNAs. The predominant fatty acids of strain TS19 were iso-C, summed feature 4 (iso-C I and/or anteiso-C B), summed feature 3 (C ω6c and/or C ω7c), and C ω5c. The major polar lipids were phosphatidylethanolamine, and one unidentified aminophospholipid. The main respiratory quinone was menaquinone-7. Based on the phylogenetic, physiological, and chemotaxonomic characteristics, strain TS19 represents a novel species, for which the name Hymenobacter taeanensis sp. nov. is proposed. The type strain is TS19 (= KCTC 72897 = JCM 34023).
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http://dx.doi.org/10.1007/s10482-021-01624-5DOI Listing
July 2021

Correction to: Spirosoma profusum sp. nov., and Spirosoma validum sp. nov., radiation-resistant bacteria isolated from soil in South Korea.

Antonie Van Leeuwenhoek 2021 Jul 15. Epub 2021 Jul 15.

Department of Bio and Environmental Technology, College of Natural Science, Seoul Women's University, Seoul, 139-774, Republic of Korea.

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http://dx.doi.org/10.1007/s10482-021-01613-8DOI Listing
July 2021

Heterogeneous nuclear ribonucleoprotein A2/B1 regulates the ERK and p53/HDM2 signaling pathways to promote the survival, proliferation and migration of non‑small cell lung cancer cells.

Oncol Rep 2021 Aug 10;46(2). Epub 2021 Jun 10.

Department of Integrative Bioscience and Biotechnology, Institute of Anticancer Medicine Development, Sejong University, Seoul 05006, Republic of Korea.

Lung cancer is the most frequent cause of cancer‑associated mortality worldwide. Upregulation of heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNPA2/B1) has been reported in non‑small cell lung cancer (NSCLC) cells, but its contribution to NSCLC remains poorly understood. hnRNPA2/B1 is involved in carcinogenesis by interacting with a number of proteins; however, little is known about its interaction with p53. The results of the present study revealed that hnRNPA2/B1 expression levels were upregulated in NSCLC cells under tumorsphere culture conditions and cisplatin treatment compared with those in cells under the adherent condition and dimethyl sulfoxide treatment, respectively, suggesting that hnRNPA2/B1 expression is induced under stress conditions. hnRNPA2/B1 knockdown decreased the number and size of NSCLC cell colonies in a clonogenic survival assay and led to a decreased migratory potential of NSCLC cells, suggesting that hnRNPA2/B1 may promote the survival, proliferation and migration of NSCLC cells. hnRNPA2/B1 knockdown induced G/G phase arrest in NSCLC cells through cyclin E degradation and phosphorylation of cyclin‑dependent kinase 2. In addition, hnRNPA2/B1 knockdown inhibited extracellular signal‑regulated kinase (ERK)1/2 phosphorylation, suggesting that hnRNPA2/B1 may promote the G/S phase transition in NSCLC cells through ERK signaling. hnRNPA2/B1 knockdown resulted in increased expression levels of p21 and p27 in NSCLC cells, as well as p53 induction and phosphorylation. Additionally, hnRNPA2/B1 knockdown inhibited human double minute 2 protein (HDM2) stability and phosphorylation, whereas overexpression of hnRNPA2 induced the opposite effects. These results suggested that hnRNPA2/B1 may promote the survival, proliferation and migration of NSCLC cells through preventing the activation of p53, which is induced by ERK‑mediated HDM2 activation. The results of the present study also indicated that the components of the hnRNPA2/B1/ERK/p53/HDM2 signaling pathway may be novel potential molecular targets for the treatment of patients with NSCLC.
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http://dx.doi.org/10.3892/or.2021.8104DOI Listing
August 2021

Voltage-Tunable Ultra-Steep Slope Atomic Switch with Selectivity over 10.

Small 2021 Jul 9;17(29):e2100401. Epub 2021 Jun 9.

Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Korea.

Atomic switch-based selectors, which utilize the formation of conductive filaments by the migration of ions, are researched for cross-point array architecture due to their simple structure and high selectivity. However, the difficulty in controlling the formation of filaments causes uniformity and reliability issues. Here, a multilayer selector with Pt/Ag-doped ZnO/ZnO/Ag-doped ZnO/Pt structure by the sputtering process is presented. A multilayer structure enables control of the filament formation by preventing excessive influx of Ag ions. The multilayer selector device exhibits a high on-current density of 2 MA cm , which can provide sufficient current for the operation with the memory device. Also, the device exhibits high selectivity of 10 and a low off-current of 10 A. The threshold voltage of selector devices can be controlled by modulating the thickness of the ZnO layer. By connecting a multilayer selector device to a resistive switching memory, the leakage current of the memory device can be reduced. These results demonstrate that a multilayer structure can be used in a selector device to improve selectivity and reliability for use in high-density memory devices.
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http://dx.doi.org/10.1002/smll.202100401DOI Listing
July 2021

Enhanced Energy Storage Performance of Polymer/Ceramic/Metal Composites by Increase of Thermal Conductivity and Coulomb-Blockade Effect.

ACS Appl Mater Interfaces 2021 Jun 3;13(23):27343-27352. Epub 2021 Jun 3.

Department of Materials Science and Engineering, Inha University, Incheon 22212, Republic of Korea.

Polymer-based dielectrics have attracted considerable attention for a wide range of applications as energy storage devices with high power. However, high loss from low thermal conductivity () and leaky current may limit their practical utilization greatly. To overcome these issues, two-dimensional hexagonal boron nitride (h-BN) modified with polydopamine (PDA) and metal palladium nanoparticles ([email protected]@Pd NPs) are introduced into a poly(vinylidene fluoride-hexafluoropropylene) P(VDF-HFP) copolymer matrix. The PDA coating improves the compatibility between the ceramic h-BN filler and the polymer matrix. Contrary to the general idea, the metallic Pd NPs enhance the breakdown strength of the polymer nanocomposites through the Coulomb-blockade effect. The nanocomposite film filled with 6 vol % [email protected]@Pd NPs exhibits significantly improved recoverable energy density () of 58.6 J cm, which is increasedby 496% compared to pure P(VDF-HFP) film, maintaining an efficiency of 65%, even under a high voltage of 500 MV m. The in-plane thermal conductivity of the nanocomposites was improved from 0.21 to 1.02 W m K with increasing ceramic h-BN content. This study suggests that a dielectric polymer with surface-engineered ceramic h-BN fillers through a Coulomb-blockade effect of metal Pd NPs might be a promising strategy for high energy storage devices.
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http://dx.doi.org/10.1021/acsami.1c01177DOI Listing
June 2021

Application of the modified handmade cloning technique to pigs.

J Anim Sci Technol 2021 Mar 31;63(2):281-294. Epub 2021 Mar 31.

Division of Animal and Dairy Science, College of Agriculture and Life Science, Chungnam National University, Daejeon 34134, Korea.

Although somatic cell nuclear transfer (SCNT) is frequently employed to produce cloned animals in laboratories, this technique is expensive and inefficient. Therefore, the handmade cloning (HMC) technique has been suggested to simplify and advance the cloning process, however, HMC wastes many oocytes and leads to mitochondrial heteroplasmy. To solve these problems, we propose a modified handmade cloning (mHMC) technique that uses simple laboratory equipment, i.e., a Pasteur pipette and an alcohol lamp, applying it to porcine embryo cloning. To validate the application of mHMC to pig cloning, embryos produced through SCNT and mHMC are compared using multiple methods, such as enucleation efficiency, oxidative stress, embryo developmental competence, and gene expression. The results show no significant differences between techniques except in the enucleation efficiency. The 8-cell and 16-cell embryo developmental competence and Oct4 expression levels exhibit significant differences. However, the blastocyst rate is not significantly different between mHMC and SCNT. This study verifies that cloned embryos derived from the two techniques exhibit similar generation and developmental competence. Thus, we suggest that mHMC could replace SCNT for simpler and cheaper porcine cloning.
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http://dx.doi.org/10.5187/jast.2021.e41DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8071742PMC
March 2021

Toxicity of the recombinant human hyaluronidase ALT-BC4 on embryonic development.

J Anim Sci Technol 2021 Mar 31;63(2):272-280. Epub 2021 Mar 31.

Division of Animal and Dairy Science, College of Agriculture and Life Science, Chungnam National University, Daejeon 34134, Korea.

Cumulus-oocyte complexes (COCs), which contain immature oocytes, are matured for in vitro embryo production. Oocyte and cumulus cells are then separated using hyaluronidase. To date, there have only been a few reported cases of the toxic effects of hyaluronidase on porcine oocytes. The aim of this study was to compare the effects of bovine testis-derived hyaluronidase and recombinant human hyaluronidase on oocyte denudation and quality. Porcine COCs were matured for 44 h and denuded using different hyaluronidase concentrations and exposure times. Then, oocytes were activated by electrical parthenogenesis. In experiment 1, COCs were denuded using bovine-derived, ovine-derived (Hirax), and human recombinant (ALT-BC4) hyaluronidases for 10 and 20 min. In experiment 2, bovine-derived and human recombinant (ALT-BC4 and ICSI Cumulase) hyaluronidases were used to denude the COCs for 2 and 20 min. In both experiments the oocytes were all completely denuded, and there was no degeneration. Rate of embryo development was significantly increased in group treated ALT-BC4 for 2 min and not significantly different in other treatment groups. In general it slightly decreased with longer exposure times. These results have confirmed that different sources of hyaluronidase do not have detrimental effects on the quality of porcine oocytes and suggest that the human recombinant hyaluronidase ALT-BC4 is suitable for oocyte denudation with an increased blastocyst rate.
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http://dx.doi.org/10.5187/jast.2021.e34DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8071738PMC
March 2021

Spirosoma profusum sp. nov., and Spirosoma validum sp. nov., radiation-resistant bacteria isolated from soil in South Korea.

Antonie Van Leeuwenhoek 2021 Jul 10;114(7):1155-1164. Epub 2021 May 10.

Department of Bio and Environmental Technology, College of Natural Science, Seoul Women's University, Seoul, 139-774, Republic of Korea.

Two novel Gram-negative, rod-shaped bacterial strains BT702 and BT704 were isolated from soil collected in Jeongseon (37° 22' 45″ N, 128° 39' 53″ E), Gangwon province, South Korea. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strains BT702 and BT704 belong to distinct lineage within the genus Spirosoma (family Cytophagaceae, order Cytophagales, class Cytophagia and phylum Bacteroidetes). The strain BT702 was closely related to Spirosoma flavus 15J11-2 (96.7% 16S rRNA gene similarity) and Spirosoma metallilatum TX0405 (93.3%). The strain BT704 was closely related to Spirosoma koreense 15J8-5 (94.6%), Spirosoma endophyticum DSM 26130 (93.8%) and Spirosoma humi S7-4-1 (93.8%). The genome sizes of type strains BT702 and BT704 are 8,731,341 bp and 8,221,062 bp, respectively. The major cellular fatty acids of strains BT702 and BT704 were C ω5c and summed feature 3 (C ω6c/C ω7c). The strains were found to have the same quinone system, with MK-7 as the major respiratory quinone. The major polar lipids of strain BT702 was identified to be phosphatidylethanolamine (PE), aminophospholipid (APL) and aminolipid (AL), while that of strain BT704 consisted of phosphatidylethanolamine (PE) and aminophospholipid (APL). Based on the polyphasic analysis (phylogenetic, chemotaxonomic and biochemical), strains BT702 and BT704 can be suggested as two new bacterial species within the genus Spirosoma and the proposed names are Spirosoma profusum and Spirosoma validum, respectively. The type strain of Spirosoma profusum is BT702 (= KCTC 82115 = NBRC 114859) and type strain of Spirosoma validum is BT704 (= KCTC 82114 = NBRC 114966).
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http://dx.doi.org/10.1007/s10482-021-01585-9DOI Listing
July 2021

Solution-processed near-infrared Cu(In,Ga)(S,Se) photodetectors with enhanced chalcopyrite crystallization and bandgap grading structure via potassium incorporation.

Sci Rep 2021 Apr 9;11(1):7820. Epub 2021 Apr 9.

Center for Opto-Electronic Materials and Devices, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea.

Although solution-processed Cu(In,Ga)(S,Se) (CIGS) absorber layers can potentially enable the low-cost and large-area production of highly stable electronic devices, they have rarely been applied in photodetector applications. In this work, we present a near-infrared photodetector functioning at 980 nm based on solution-processed CIGS with a potassium-induced bandgap grading structure and chalcopyrite grain growth. The incorporation of potassium in the CIGS film promotes Se uptake in the bulk of the film during the chalcogenization process, resulting in a bandgap grading structure with a wide space charge region that allows improved light absorption in the near-infrared region and charge carrier separation. Also, increasing the Se penetration in the potassium-incorporated CIGS film leads to the enhancement of chalcopyrite crystalline grain growth, increasing charge carrier mobility. Under the reverse bias condition, associated with hole tunneling from the ZnO interlayer, the increasing carrier mobility of potassium-incorporated CIGS photodetector improved photosensitivity and particularly external quantum efficiency more than 100% at low light intensity. The responsivity and detectivity of the potassium-incorporated CIGS photodetector reach 1.87 A W and 6.45 [Formula: see text] 10 Jones, respectively, and the - 3 dB bandwidth of the device extends to 10.5 kHz under 980 nm near-infrared light.
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http://dx.doi.org/10.1038/s41598-021-87359-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8035197PMC
April 2021

The Inhibitory Effects of Plant Derivate Polyphenols on the Main Protease of SARS Coronavirus 2 and Their Structure-Activity Relationship.

Molecules 2021 Mar 30;26(7). Epub 2021 Mar 30.

Institutes of Green Bioscience and Technology, Seoul National University, Pyeongchang-gun 25354, Gang-won-do, Korea.

The main protease (M) is a major protease having an important role in viral replication of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the novel coronavirus that caused the pandemic of 2020. Here, active M was obtained as a 34.5 kDa protein by overexpression in BL21 (DE3). The optimal pH and temperature of M were 7.5 and 37 °C, respectively. M displayed a value of 16 μM with Dabcyl-KTSAVLQ↓SGFRKME-Edans. Black garlic extract and 49 polyphenols were studied for their inhibitory effects on purified M. The IC values were 137 μg/mL for black garlic extract and 9-197 μM for 15 polyphenols. The mixtures of tannic acid with puerarin, daidzein, and/or myricetin enhanced the inhibitory effects on M. The structure-activity relationship of these polyphenols revealed that the hydroxyl group in C3', C4', C5' in the B-ring, C3 in the C-ring, C7 in A-ring, the double bond between C2 and C3 in the C-ring, and glycosylation at C8 in the A-ring contributed to inhibitory effects of flavonoids on M.
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http://dx.doi.org/10.3390/molecules26071924DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8036510PMC
March 2021

Effects of Conserved Wedge Domain Residues on DNA Binding Activity of RecG Helicase.

Front Genet 2021 4;12:634615. Epub 2021 Feb 4.

Radiation Research Division, Korea Atomic Energy Research Institute, Jeongeup, South Korea.

is extremely resistant to ionizing radiation and has an exceptional ability to repair DNA damage caused by various DNA-damaging agents. uses the same DNA-repair strategies as other prokaryotes, but certain proteins involved in the classical DNA repair machinery have characteristics different from their counterparts. RecG helicase, which unwinds a variety of branched DNA molecules, such as Holliday junctions (HJ) and D-loops, plays important roles in DNA repair, recombination, and replication. Primary sequence analysis of RecG from a number of bacterial species revealed that three amino acids (QPW) in the DNA-binding wedge domain (WD) are well-conserved across the RecG proteins. Interactions involving these conserved residues and DNA substrates were predicted in modeled domain structures of RecG (DrRecG). Compared to the WD of RecG protein (EcRecG) containing FSA amino acids corresponding to QPW in DrRecG, the HJ binding activity of DrRecG-WD was higher than that of EcRecG-WD. Reciprocal substitution of FSA and QPW increased and decreased the HJ binding activity of the mutant WDs, EcRecG-WD, and DrRecG-WD, respectively. Following -irradiation treatment, the reduced survival rate of DrRecG mutants (Δ) was fully restored by the expression of DrRecG, but not by that of EcRecG. EcRecG also enhanced -radioresistance of Δ, whereas DrRecG did not. Δ cells complemented by DrRecG and EcRecG reconstituted an intact genome within 3 h post-irradiation, as did the wild-type strain, but Δ with EcRecG and DrRecG exhibited a delay in assembly of chromosomal fragments induced by -irradiation. These results suggested that the QPW residues facilitate the association of DrRecG with DNA junctions, thereby enhancing the DNA repair efficiency of DrRecG.
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http://dx.doi.org/10.3389/fgene.2021.634615DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7889586PMC
February 2021

Lycopene Improves In Vitro Development of Porcine Embryos by Reducing Oxidative Stress and Apoptosis.

Antioxidants (Basel) 2021 Feb 3;10(2). Epub 2021 Feb 3.

Futuristic Animal Resource & Research Center, Korea Research Institute of Bioscience and Biotechnology, Chungcheongbuk-do, Cheongju 28116, Korea.

In vitro culture (IVC) for porcine embryo development is inferior compared to in vivo development because oxidative stress can be induced by the production of excessive reactive oxygen species (ROS) under high oxygen tension in the in vitro environment. To overcome this problem, we investigated the effect of lycopene, an antioxidant carotenoid, on developmental competence and the mechanisms involved in mitochondria-dependent apoptosis pathways in porcine embryos. In vitro fertilized (IVF) embryos were cultured in IVC medium supplemented with 0, 0.02, 0.05, 0.1, or 0.2 μM lycopene. The results indicate that 0.1 μM lycopene significantly increased the rate of blastocyst formation and the total cell numbers, including trophectoderm cell numbers, on Day In terms of mitochondria-dependent apoptosis, IVF embryos treated with 0.1 μM lycopene exhibited significantly decreased levels of ROS, increased mitochondrial membrane potential, and decreased expression of cytochrome c on Days 2 and Furthermore, 0.1 μM lycopene significantly decreased the number and percentage of caspase 3-positive and apoptotic cells in Day-6 blastocysts. In addition, Day-2 embryos and Day-6 blastocysts treated with 0.1 μM lycopene showed significantly reduced mRNA expression related to antioxidant enzymes () and apoptosis ( ratio). These results indicate that lycopene supplementation during the entire period of IVC enhanced embryonic development in pigs by regulating oxidative stress and mitochondria-dependent apoptosis.
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http://dx.doi.org/10.3390/antiox10020230DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7913612PMC
February 2021

CMOS-compatible ferroelectric NAND flash memory for high-density, low-power, and high-speed three-dimensional memory.

Sci Adv 2021 Jan 13;7(3). Epub 2021 Jan 13.

Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea.

Ferroelectric memory has been substantially researched for several decades as its potential to obtain higher speed, lower power consumption, and longer endurance compared to conventional flash memory. Despite great deal of effort to develop ferroelectric memory based on perovskite oxides on Si, formation of unwanted interfacial layer substantially compromises the performance of the ferroelectric memory. Furthermore, three-dimensional (3D) integration has been unimaginable because of high processing temperature, non-CMOS compatibility, difficulty in scaling, and complex compositions of perovskite oxides. Here, we demonstrate a unique strategy to tackle critical issues by applying hafnia-based ferroelectrics and oxide semiconductors. Thus, it is possible to avoid the formation of interfacial layer that finally allows unprecedented Si-free 3D integration of ferroelectric memory. This strategy yields memory performance that could be achieved neither by the conventional flash memory nor by the previous perovskite ferroelectric memories. Device simulation confirms that this strategy can realize ultrahigh-density 3D memory integration.
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http://dx.doi.org/10.1126/sciadv.abe1341DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7806215PMC
January 2021

Effect of the volumetric dimensions of a complete arch on the accuracy of scanners.

J Adv Prosthodont 2020 Dec 28;12(6):361-368. Epub 2020 Dec 28.

Department of Dental Science, Graduate School, Kyungpook National University, Daegu, Republic of Korea.

Purpose: The present study aimed to evaluate the accuracy of a desktop scanner and intraoral scanners based on the volumetric dimensions of a complete arch.

Materials And Methods: Seven reference models were fabricated based on the volumetric dimensions of complete arch (70%, 80%, 90%, 100%, 110%, 120%, and 130%). The reference models were digitized using an industrial scanner (Solutionix C500; MEDIT) for the fabrication of a computer-aided design (CAD) reference model (CRM). The reference models were digitized using three intraoral scanners (CS3600, Trios3, and i500) and one desktop scanner (E1) to fabricate a CAD test model (CTM). CRM and CTM were then superimposed using inspection software, and 3D analysis was conducted. For statistical analysis, one-way analysis of variance was used to verify the difference in accuracy based on the volumetric dimensions of the complete arch and the accuracy based on the scanners, and the differences among the groups were analyzed using the Tukey HSD test as a post-hoc test (α=.05).

Results: The three different scanners showed a significant difference in accuracy based on the volumetric dimensions of the complete arch (<.05), but the desktop scanner did not show a significant difference in accuracy based on the volumetric dimensions of the complete arch (=.808).

Conclusion: The accuracy of the intraoral scanners was dependent on the volumetric dimensions of the complete arch, but the volumetric dimensions of the complete arch had no effect on the accuracy of the desktop scanner. Additionally, depending on the type of intraoral scanners, the accuracy differed according to the volumetric dimensions of the complete arch.
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http://dx.doi.org/10.4047/jap.2020.12.6.361DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7790599PMC
December 2020

Vibrio cholerae FruR facilitates binding of RNA polymerase to the fru promoter in the presence of fructose 1-phosphate.

Nucleic Acids Res 2021 02;49(3):1397-1410

School of Biological Sciences and Institute of Microbiology, Seoul National University, Seoul 08826, Korea.

In most bacteria, efficient use of carbohydrates is primarily mediated by the phosphoenolpyruvate (PEP):carbohydrate phosphotransferase system (PTS), which concomitantly phosphorylates the substrates during import. Therefore, transcription of the PTS-encoding genes is precisely regulated by transcriptional regulators, depending on the availability of the substrate. Fructose is transported mainly through the fructose-specific PTS (PTSFru) and simultaneously converted into fructose 1-phosphate (F1P). In Gammaproteobacteria such as Escherichia coli and Pseudomonas putida, transcription of the fru operon encoding two PTSFru components, FruA and FruB, and the 1-phosphofructokinase FruK is repressed by FruR in the absence of the inducer F1P. Here, we show that, contrary to the case in other Gammaproteobacteria, FruR acts as a transcriptional activator of the fru operon and is indispensable for the growth of Vibrio cholerae on fructose. Several lines of evidence suggest that binding of the FruR-F1P complex to an operator which is located between the -35 and -10 promoter elements changes the DNA structure to facilitate RNA polymerase binding to the promoter. We discuss the mechanism by which the highly conserved FruR regulates the expression of its target operon encoding the highly conserved PTSFru and FruK in a completely opposite direction among closely related families of bacteria.
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http://dx.doi.org/10.1093/nar/gkab013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7897506PMC
February 2021

Spirosoma taeanense sp. nov., a radiation resistant bacterium isolated from a coastal sand dune.

Antonie Van Leeuwenhoek 2021 Feb 15;114(2):151-159. Epub 2021 Jan 15.

Radiation Research Division, Korea Atomic Energy Research Institute, Jeongeup, 56212, Republic of Korea.

An aerobic, Gram-negative, non-motile, non-spore-forming, rod-shaped, and pale yellow-colored bacterial strain, designated TS118, was isolated from a sand sample obtained from a coastal sand dune after exposure to 3 kGy of gamma radiation. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the isolate was a member of the genus Spirosoma and most closely related to Spirosoma metallicum PR1014k (95.1% similarity). The genome of strain TS118 is constituted by one chromosome (5,691,492 bp) and one plasmid (28,440 bp) and has a G + C content of 52.7%. The genome contains 4641 protein coding sequences (CDSs), 38 tRNAs, and 11 rRNAs. The predominant fatty acids of strain TS118 were C ω5c, iso-C, C, summed feature 3 (C ω6c and/or C ω7c), and iso-C 3-OH. The major polar lipids were phosphatidylethanolamine, an unidentified amino lipid and an unidentified aminophospholipid. The main respiratory quinone was menaquinone-7 (MK-7). The novel strain showed resistance to gamma radiation with a D value (i.e., the dose required to reduce the bacterial population by tenfold) of 4.3 kGy. Based on the phylogenetic, physiological, and chemotaxonomic characteristics, strain TS118 represents a novel species, for which the name Spirosoma taeanense sp. nov. is proposed. The type strain is TS118 (=KCTC 72898 =JCM 34024).
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http://dx.doi.org/10.1007/s10482-020-01508-0DOI Listing
February 2021

The mechano-response of murine annulus fibrosus cells to cyclic tensile strain is frequency dependent.

JOR Spine 2020 Dec 20;3(4):e21114. Epub 2020 Jul 20.

Department of Physiology and Pharmacology Schulich School of Medicine & Dentistry, The University of Western Ontario London Ontario Canada.

The intervertebral disk (IVD) is a composite structure essential for spine stabilization, load bearing, and movement. Biomechanical factors are important contributors to the IVD microenvironment regulating joint homeostasis; however, the cell type-specific effectors of mechanotransduction in the IVD are not fully understood. The current study aimed to determine the effects of cyclic tensile strain (CTS) on annulus fibrosus (AF) cells and identify mechano-sensitive pathways. Using a cell-type specific reporter mouse to differentiation NP and AF cells from the murine IVD, we characterized AF cells in dynamic culture exposed to CTS (6% strain) at specific frequencies (0.1 Hz, 1.0 Hz, or 2.0 Hz). We demonstrate that our culture model maintains the phenotype of primary AF cells and that the bioreactor system delivers uniform biaxial strain across the cell culture surface. We show that exposure of AF cells to CTS induces cytoskeleton reorganization resulting in stress fiber formation, with acute exposure to CTS at 2.0 Hz inducing a significant yet transient increase ERK1/2 pathway activation. Using SYBPR-based qPCR to assess the expression of extracellular matrix (ECM) genes, ECM-remodeling genes, candidate mechano-sensitive genes, inflammatory cytokines and cell surface receptors, we demonstrated that exposure of AF cells to CTS at 0.1 Hz increased , , and expression. AF cells exposed to CTS at 1.0 Hz showed a significant increase in the expression of , , and . Exposure of AF cells to CTS at 2.0 Hz induced a significant increase in , , , , , and expression. Among the cell surface receptors assessed, AF cells exposed to CTS at 2.0 Hz showed a significant increase in , , and expression Our findings demonstrate that the response of AF cells to CTS is frequency dependent and suggest that mechanical loading may directly contribute to matrix remodeling and the onset of local tissue inflammation in the murine IVD.
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http://dx.doi.org/10.1002/jsp2.1114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7770207PMC
December 2020

Expression level of leucine-rich repeat containing 15 regulates characteristics of dermal papilla cells of human hair follicle.

J Dermatol Sci 2021 Feb 29;101(2):134-137. Epub 2020 Sep 29.

Department of Immunology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea. Electronic address:

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http://dx.doi.org/10.1016/j.jdermsci.2020.09.013DOI Listing
February 2021

Emerging Materials for Neuromorphic Devices and Systems.

iScience 2020 Dec 24;23(12):101846. Epub 2020 Nov 24.

Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea.

Neuromorphic devices and systems have attracted attention as next-generation computing due to their high efficiency in processing complex data. So far, they have been demonstrated using both machine-learning software and complementary metal-oxide-semiconductor-based hardware. However, these approaches have drawbacks in power consumption and learning speed. An energy-efficient neuromorphic computing system requires hardware that can mimic the functions of a brain. Therefore, various materials have been introduced for the development of neuromorphic devices. Here, recent advances in neuromorphic devices are reviewed. First, the functions of biological synapses and neurons are discussed. Also, deep neural networks and spiking neural networks are described. Then, the operation mechanism and the neuromorphic functions of emerging devices are reviewed. Finally, the challenges and prospects for developing neuromorphic devices that use emerging materials are discussed.
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http://dx.doi.org/10.1016/j.isci.2020.101846DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7725950PMC
December 2020

Morphological-Electrical Property Relation in Cu(In,Ga)(S,Se) Solar Cells: Significance of Crystal Grain Growth and Band Grading by Potassium Treatment.

Small 2020 Dec 4;16(48):e2003865. Epub 2020 Nov 4.

Clean Energy Research Center, Korea Institute of Science and Technology, 5, Hwarang-ro 14-gil, Seongbuk-gu, Seoul, 02792, Republic of Korea.

Solution-processed Cu(In,Ga)(S,Se)  (CIGS) has a great potential for the production of large-area photovoltaic devices at low cost. However, CIGS solar cells processed from solution exhibit relatively lower performance compared to vacuum-processed devices because of a lack of proper composition distribution, which is mainly instigated by the limited Se uptake during chalcogenization. In this work, a unique potassium treatment method is utilized to improve the selenium uptake judiciously, enhancing grain sizes and forming a wider bandgap minimum region. Careful engineering of the bandgap grading structure also results in an enlarged space charge region, which is favorable for electron-hole separation and efficient charge carrier collection. Besides, this device processing approach has led to a linearly increasing electron diffusion length and carrier lifetime with increasing the grain size of the CIGS film, which is a critical achievement for enhancing photocurrent yield. Overall, 15% of power conversion efficiency is achieved in solar cells processed from environmentally benign solutions. This approach offers critical insights for precise device design and processing rules for solution-processed CIGS solar cells.
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http://dx.doi.org/10.1002/smll.202003865DOI Listing
December 2020

Spirosoma aureum sp. nov., and Hymenobacter russus sp. nov., radiation-resistant bacteria in Cytophagales order isolated from soil.

Antonie Van Leeuwenhoek 2020 Dec 4;113(12):2201-2212. Epub 2020 Nov 4.

Department of Bio and Environmental Technology, College of Natural Science, Seoul Women's University, Seoul, 01797, Korea.

A Gram-stain-negative, aerobic, nonmotile, yellow-colored strain BT328 and Gram-stain-negative, aerobic, non-motile, red-colored strain BT18 were isolated from the soil collected in Korea. Phylogenetic analyses based on 16S rRNA gene sequence revealed that strain BT328 formed a distinct lineage within the family Spirosomaceae (order Cytophagales, class Cytophagia) and was most closely related to a member of the genus Spirosoma, Spirosoma terrae 15J9-4 (95.9% 16S rRNA gene sequence similarity). Optimal growth occurred at 25 °C, pH 7.0 and in the absence of NaCl. The predominant cellular fatty acids were summed feature 3 (C ω6c/C ω7c) and C ω5c. The major respiratory quinone was MK-7. The major polar lipid was phosphatidylethanolamine. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain BT18 formed a distinct lineage within the family Hymenobacteraceae (order Cytophagales, class Cytophagia, phylum Bacteroidetes) and was most closely related to members of the genus Hymenobacter, Hymenobacter knuensis 16F7C-2 (97.0% 16S rRNA gene sequence similarity). Optimal growth occurred at 25 °C and pH 7.0 without NaCl. The major fatty acids were iso-C and anteiso-C. The major menaquinone was MK-7. The major polar lipid was phosphatidylethanolamine. Biochemical, chemotaxonomic and phylogenetic analyses indicated that strains BT328 and BT18 represents a novel bacterial species within the genus Spirosoma and Hymenobacter, respectively. For which the name Spirosoma aureum and Hymenobacter russus is proposed. The type strain of S. aureum is BT328 (=KCTC 72365 = NBRC 114506) and the type strain of H. russus is BT18 (=KCTC 62610 = NBRC 114380).
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http://dx.doi.org/10.1007/s10482-020-01492-5DOI Listing
December 2020

Real-World Experience of Pembrolizumab Monotherapy in Patients with Recurrent or Persistent Cervical Cancer: A Korean Multi-Center Retrospective Study (KGOG1041).

Cancers (Basel) 2020 Oct 29;12(11). Epub 2020 Oct 29.

Department of Obstetrics and Gynecology, Yonsei University College of Medicine, Seoul 03722, Korea.

This study investigated the antitumor activity and safety of pembrolizumab in patients with recurrent cervical cancer in real-world practice. We conducted a multi-center retrospective study of patients with recurrent or persistent cervical cancer treated with pembrolizumab at sixteen institutions in Korea between January 2016 and March 2020. The primary endpoints were the objective response rate (ORR) and safety. Data were available for 117 patients. The median age was 53 years (range, 28-79). Sixty-four (54.7%) patients had an Eastern Cooperative Oncology Group (ECOG) performance status of ≥2. Forty-nine (41.9%) patients were stage ≥III at diagnosis. Eighty-eight (75.2%) patients had squamous cell carcinoma. The median number of prior chemotherapy lines was two (range, 1-6). During the median follow-up of 4.9 months (range, 0.2-35.3), the ORR was 9.4%, with three complete responses and eight partial responses. The median time to response was 2.8 months (range 1.3-13.1), and the median duration of response (DOR) was not reached. In the population of patients with favorable performance status (ECOG ≤1) ( = 53), the ORR was 18.9%, and the median DOR was 8.9 months (range, 7.3-10.4). Adverse events occurred in 55 (47.0%) patients, including eight (6.8%) patients who experienced grade ≥3 events, and two of them were suspicious treatment-related deaths. Pembrolizumab had modest antitumor activity in patients with recurrent cervical cancer comparable to that found in previously reported clinical trials. However, in patients with favorable performance status, pembrolizumab showed effective antitumor activity. Some safety profiles should be carefully monitored during treatment.
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http://dx.doi.org/10.3390/cancers12113188DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7693862PMC
October 2020

Rhodocytophaga rosea sp. nov. and Nibribacter ruber sp. nov., two radiation-resistant bacteria isolated from soil.

Antonie Van Leeuwenhoek 2020 Dec 2;113(12):2177-2185. Epub 2020 Nov 2.

Department of Bio and Environmental Technology, College of Natural Science, Seoul Women's University, Seoul, 01797, Republic of Korea.

Two bacterial strains, 172606-1 and BT10, were isolated from soil, Korea. Both strains were Gram-stain-negative and rod-shaped bacteria. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain 172606-1 formed a distinct lineage within the family Cytophagaceae (order Cytophagales, class Cytophagia, phylum Bacteroidetes). Strain 172606-1 was most closely related to a member of the genus Rhodocytophaga (93.8% 16S rRNA gene sequence similarity to Rhodocytophaga aerolata 5416T-29). The complete genome sequence of strain 172606-1 is 8,983,451 bp size. Optimal growth occurred at 25 °C and pH 7.0 without NaCl. The major cellular fatty acids were identified as iso-C and C ω5c. The major respiratory quinone was MK-7. The major polar lipid was phosphatidylethanolamine. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain BT10 belongs to the genus Nibribacter and is closely related to Nibribacter koreensis GSR 3061 (96.5%), Rufibacter glacialis MDT1-10-3 (95.7%), Rufibacter sediminis H-1 (95.1%) and Rufibacter quisquiliarum CAI-18b (94.9%). The complete genome sequence of strain BT10 is 4,374,810 bp size. The predominant (> 10%) cellular fatty acids of strain BT10 were iso-C and summed feature 4 (anteiso-C B/iso-C I) and a predominant quinone was MK-7. In addition, strain BT10 has phosphatidylethanolamine (PE) as the major polar lipid. On the basis of biochemical, chemotaxonomic and phylogenetic analyses, strain 172606-1 represents a novel bacterial species of the genus Rhodocytophaga, for which the name Rhodocytophaga rosea is proposed and strain BT10 represents a novel species of the genus Nibribacter, for which the name Nibribacter ruber is proposed. The type strains of Rhodocytophaga rosea and Nibribacter ruber are 172606-1 (= KCTC 62096 = NBRC 114410) and BT10 (= KCTC 62607 = NBRC 114383), respectively.
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http://dx.doi.org/10.1007/s10482-020-01488-1DOI Listing
December 2020

Hymenobacter busanensis sp. nov., radiation-resistant species isolated from soil in South Korea.

Arch Microbiol 2021 Mar 12;203(2):755-762. Epub 2020 Oct 12.

Department of Bio and Environmental Technology, College of Natural Science, Seoul Women's University, Seoul, 139-774, Republic of Korea.

Two bacterial strains designated as MA3 and BT182 were isolated from a soil sample in South Korea. Cells of the two strains were Gram-stain-negative, non-motile, rod-shaped and formed red colonies on R2A agar at 25 °C. The 16S rRNA genes of the two strains shared a sequence similarity of 99.8%. Both strains shared the highest 16S rRNA gene similarity of 96.8% with Hymenobacter edaphi NL, followed by Hymenobacter paludis KBP-30 (96.3%), Hymenobacter coalescens WW84 (96.3%) and Hymenobacter gummosus ANT-18 (96.3%). Growth was observed at 15-37 °C (optimum 30 °C), pH 6-8 (optimum pH 7) and in the presence up to 1% NaCl. The genome size of strains MA3 and BT182 is 4.9 Mb and 4.8 Mb, respectively. The genomic G + C content of both strains is 62.0 mol%. The main polar lipid of the strains was phosphatidylethanolamine, the only respiratory quinone detected was menaquinone-7 and the major fatty acids were anteiso-C, iso-C, summed feature 4 (iso-C I/anteiso-C B) and summed feature 3 (C ω6c/C ω7c), supporting the affiliation of these strains with the genus Hymenobacter. Based on the phylogenetic, genotypic, phenotypic and chemotaxonomic data, strains MA3 and BT182 represent a novel species of the genus Hymenobacter, for which the name Hymenobacter busanensis is proposed. The type strain is MA3 (= KCTC 72631 = NBRC 114193).
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http://dx.doi.org/10.1007/s00203-020-02080-xDOI Listing
March 2021

Hymenobacter baengnokdamensis sp. nov., Isolated from the Soil of a Crater Lake in Korea.

Curr Microbiol 2020 Dec 6;77(12):4167-4173. Epub 2020 Oct 6.

Radiation Research Division, Korea Atomic Energy Research Institute, Jeongeup, 56212, Republic of Korea.

An aerobic, Gram-stain-negative, non-motile, non-spore-forming, rod-shaped and pink-colored bacterial strain, designated BRD72, was isolated from a crater lake (Baengnokdam) at the top of Mt. Hallasan in the Republic of Korea. Cells were catalase-positive and oxidase-negative. Phylogenetic analysis based on the 16S rRNA gene sequences revealed that the isolate was a member of the genus Hymenobacter and most closely related to Hymenobacter marinus KJ035 (96.2% similarity). The isolate was found to produce carotenoid pigment, but not flexirubin-type pigment. The predominant fatty acids of strain BRD72 were summed feature 3 (C ω7c and/or C ω6c, 21.6%), iso-C (17.9%), anteiso-C (13.3%) and summed feature 4 (iso-C I and/or anteiso-C B, 11.3%). The major polar lipids were phosphatidylethanolamine, an unidentified amino lipid, and two unidentified aminophospholipids. The main respiratory quinone was menaquinone-7 (MK-7), and the main polyamine was homospermidine. The DNA G+C content was 59.8 mol%. Based on the phylogenetic, physiological, and chemotaxonomic characteristics, strain BRD72 represents a novel species, for which the name Hymenobacter baengnokdamensis sp. nov. is proposed. The type strain is BRD72 (= KCTC 72649 = JCM 33837).
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http://dx.doi.org/10.1007/s00284-020-02225-7DOI Listing
December 2020

Performance evaluation of an amplicon-based next-generation sequencing panel for BRCA1 and BRCA2 variant detection.

J Clin Lab Anal 2020 Dec 19;34(12):e23524. Epub 2020 Aug 19.

Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

Background: As next-generation sequencing (NGS) technology matures, various amplicon-based NGS tests for BRCA1/2 genotyping have been introduced. This study was designed to evaluate an NGS test using a newly released amplicon-based panel, AmpliSeq for Illumina BRCA Panel (AmpliSeq panel), for detection of clinically significant BRCA variants, and to compare it to another amplicon-based NGS test confirmed by Sanger sequencing.

Methods: We reviewed BRCA test results done by NGS using the TruSeq Custom Amplicon kit from patients suspected of hereditary breast/ovarian cancer syndrome (HBOC) in 2018. Of those, 96 residual samples with 100 clinically significant variants were included in this study using predefined criteria: 100 variants were distributed throughout the BRCA1 and BRCA2 genes. All target variants were confirmed by Sanger sequencing. Duplicate NGS testing of these samples was performed using the AmpliSeq panel, and the concordance of results from the two amplicon-based NGS tests was assessed.

Results: Ninety-nine of 100 variants were detected in duplicate BRCA1/2 genotyping using the AmpliSeq panel (sensitivity, 99%; specificity, 100%). In the discordant case, one variant (BRCA1 c.3627dupA) was found only in repeat 1, but not in repeat 2. Automated nomenclature of all variants, except for two indel variants, was in consensus with Human Genome Variation Society nomenclature.

Conclusion: Our findings confirm that the analytic performance of the AmpliSeq panel is satisfactory, with high sensitivity and specificity.
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http://dx.doi.org/10.1002/jcla.23524DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7755770PMC
December 2020

Crystal structure of the AhpD-like protein DR1765 from Deinococcus radiodurans R1.

Biochem Biophys Res Commun 2020 08 1;529(2):444-449. Epub 2020 Jul 1.

Radiation Research Division, Korea Atomic Energy Research Institute, Jeongeup, 56212, Republic of Korea. Electronic address:

Deinococcus radiodurans is well known for its extreme resistance to ionizing radiation (IR). Since reactive oxygen species generated by IR can damage various cellular components, D. radiodurans has developed effective antioxidant systems to cope with this oxidative stress. dr1765 from D. radiodurans is predicted to encode an alkyl hydroperoxidase-like protein (AhpD family), which is implicated in the reduction of hydrogen peroxide (HO) and organic hydroperoxides. In this study, we constructed a dr1765 mutant strain (Δdr1765) and examined the survival rate after HO treatment. Δdr1765 showed a significant decrease in the HO resistance compared to the wild-type strain. We also determined the crystal structure of DR1765 at 2.27 Å resolution. DR1765 adopted an all alpha helix protein fold representative of the AhpD-like superfamily. Structural comparisons of DR1765 with its structural homologues revealed that DR1765 possesses the Glu74-Cys86-Tyr88-Cys89-His93 signature motif, which is conserved in the proton relay system of AhpD. Complementation of Δdr1765 with dr1765 encoding C86A or C89A mutation failed to restore the survival rate to wild-type level. Taken together, these results suggest that DR1765 might function as an AhpD to protect cells from oxidative stress.
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http://dx.doi.org/10.1016/j.bbrc.2020.06.061DOI Listing
August 2020

Expression dynamics of integrin α2, α3, and αV upon osteogenic differentiation of human mesenchymal stem cells.

Stem Cell Res Ther 2020 06 3;11(1):210. Epub 2020 Jun 3.

Department of Integrative Bioscience and Biotechnology, Institute of Anticancer Medicine Development, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul, 05006, Korea.

Background: The differentiation of human mesenchymal stem cells (hMSCs) into osteoblasts (OBs) is a prerequisite for bone formation. However, little is known about the definitive surface markers for OBs during osteogenesis.

Methods: To study the surface markers on OBs, we generated and used monoclonal antibodies (MAbs) against surface molecules on transforming growth factor-β1 (TGF-β1)-treated cancer cells. The generated MAbs were further selected toward expression changes on hMSCs cultured with TGF-β1/bone morphogenetic protein-2 (BMP-2) or osteogenic differentiation medium (ODM) by flow cytometry. Immunoprecipitation and mass spectrometry were performed to identify target antigens of selected MAbs. Expression changes of the target antigens were evaluated in hMSCs, human periodontal ligament cells (hPDLCs), and human dental pulp cells (hDPCs) during osteogenic and adipogenic differentiation by quantitative polymerase chain reaction (qPCR) and flow cytometry. hMSCs were also sorted by the MAbs using magnetic-activated cell sorting system, and osteogenic potential of sorted cells was evaluated via Alizarin Red S (ARS) staining and qPCR.

Results: The binding reactivity of MR14-E5, one of the MAbs, was downregulated in hMSCs with ODM while the binding reactivity of ER7-A7, ER7-A8, and MR1-B1 MAbs was upregulated. Mass spectrometry and overexpression identified that MR14-E5, ER7-A7/ER7-A8, and MR1-B1 recognized integrin α2, α3, and αV, respectively. Upon osteogenic differentiation of hMSCs, the expression of integrin α2 was drastically downregulated, but the expression of integrin α3 and αV was upregulated in accordance with upregulation of osteogenic markers. Expression of integrin α3 and αV was also upregulated in hPDLCs and hDPCs during osteogenic differentiation. Cell sorting showed that integrin αV-high hMSCs have a greater osteogenic potential than integrin αV-low hMSCs upon the osteogenic differentiation of hMSCs. Cell sorting further revealed that the surface expression of integrin αV is more dramatically induced even in integrin αV-low hMSCs.

Conclusion: These findings suggest that integrin α3 and αV induction is a good indicator of OB differentiation. These findings also shed insight into the expression dynamics of integrins upon osteogenic differentiation of hMSCs and provide the reason why different integrin ligands are required for OB differentiation of hMSCs.
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http://dx.doi.org/10.1186/s13287-020-01714-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7268774PMC
June 2020

Heterosynaptic Plasticity Emulated by Liquid Crystal-Carbon Nanotube Composites with Modulatory Interneurons.

ACS Appl Mater Interfaces 2020 Jun 2;12(24):27467-27475. Epub 2020 Jun 2.

Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea.

The aim of the neuromorphic computing is to emulate energy-efficient and smart data-processing ability of the biological brain, which is achieved by massively interconnected neurons and synapses. The strength of a connection between two neurons is modified by homosynaptic and heterosynaptic plasticity. As current research in the neuromorphic device is mainly focused on emulating homosynaptic plasticity, complex biological functions are not easy to mimic because they require both homosynaptic and heterosynaptic plasticity. We demonstrate the use of a liquid crystal-carbon nanotube (LC-CNT) composite as a resistive switching material that can emulate both the homosynaptic and heterosynaptic functions of biological neurons. The LC-CNT composite undergoes resistance change by CNT alignment and aggregated wire formation subjected to an applied electric field. A two-terminal device that exploits this mechanism achieves analog switching and homosynaptic potentiation. In a multiterminal device structure, the modulatory interneuron could tune the synaptic properties to perform heterosynaptic functions such as heterosynaptic potentiation, heterosynaptic facilitation, and synaptic weight normalization to emulate complex biological functions of a brain. Artificial synapses that exploit this multifunctionality of the LC-CNT composite have uses in next-generation neuromorphic devices.
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http://dx.doi.org/10.1021/acsami.0c01775DOI Listing
June 2020
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