• Microbiology and Biotechnology Letters
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• v.24 no.1
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• pp.9-18
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• 1996

Streptococcus mutans has been implicated as primary causative agents of dental caries by insoluble glucan (IG) in human and experimental animals. An attempt was made to search for the ${\alpha}$-1,3 glucanase that degrades IG produced by S. mutans. ${\alpha}$-1,3 glucanase was detected in the culture supernatant of microorganisms, which are isolated from soils on agar medium containing IG as a sole carbon source. This Streptomyces sp. hydrolysed IG produced by immobilized S. mutans and was named as Y9373. This enzyme required ${\alpha}$-1,3 glucan (IG) as an inducer. The optimum conditions for enzyme production were studied. The enzyme was purified by 30~70% $(NH_4)_2SO_4$ precipitation, anion exchange chroma tography on DEAE-cellulose and gel filtration on Sepadex G-75. The purified enzyme has a specific activity of 7840.0 U/mg protein giving 32.1-fold purification and final yield of 0.53%. The molecular weight was estimated to be about 22.5 kDa by SDS-PAGE. The optimum pH and temperature for enzyme reaction were 6.5 and 37$^{\circ}C$, respectively and the enzyme was relatively stable at the temperature below 60$^{\circ}C$. The activity of purified enzyme was enhanced by adding $Co^{2+},\;Mn^{2+}\;and\;Mg^{2+}$ into the medium, whereas inhibited by adding $Hg^{2+},\;Zn^{2+}$ and SDS. The $K_m\;and\;V_{max}$ value of ${\alpha}$-1,3 glucanase for IG were estimated to be 2.50 mM and 0.0431 mM/min, respectively. The thin layer chromatographic analysis of hydrolysates from IG with ${\alpha}$-1,3 glucanase showed that glucose was the main product of reaction. This enzyme activity was about 14 times higher than marketing dextranase as preventive agent against artificial dental caries by S. mutans in TH medium including 5% sucrose after 30 minutes.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.6
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• pp.806-811
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• 2003

Effects of pH, temperature, light, sugars, organic acids, metal ions, ascorbic acid, thiamine nicotinic acid and pyridoxine on the stability of the color of the cranberry solution were investigated. The pH had marked influences on the color of the cranberry solution: i.e., the color of the cranberry solution was more intense at low pH. It showed characteristic bathochromic shift as the pH of the solution increased. The half-lives of olor value were 34 days at 37$^{\circ}C$, 91 mins at 9$0^{\circ}C$ and 29 mins at 12$0^{\circ}C$. Light gave an adverse effect to the stability of the color. The color degradation can be minimized by shielding the light from the cranberry solution. Among the sugars tested, fructose was the most deleterious followed by sucrose, galactose, maltose and glucose. Fumaric acid was found to be the most effective in stabilizing the color followed by citric acid, malic acid, acetic acid, while tartaric acid was found to be deleterious. Among the metal ions tested N $a^{+}$ and $Mg^{2+}$ were found to be effective in stabilizing the color, while M $n^{2+}$ was found to be the most deleterious followed by F $e^{2+}$, $K^{+}$ and $Ca^{2+}$. Ascorbic acid was found to be deleterious considerably followed by thiamine, while nicotinic acid and pyridoxine were found to be effective in stabilizing the color feebly.or feebly.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.11
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• pp.1422-1426
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• 2008

The purpose of this study was to test characteristics between normal and autistic children via comparison of nutrient intakes, hair mineral, blood free radical, and serotonin contents. A total of 50 children aged 3-9 were divided into two main groups of normal control children (n=22) and autistic children (n=28) tested by child psychiatrist. The nutrient intakes by 24-hour recall method were no significantly different between the two groups. The concentrations of toxic mineral, such as cadmium (Cd) and lead (Pb) in hair of autistic children were significantly higher, while concentration of antioxidant mineral (Cu, Zn, Fe) was lower than that of normal children. The autistic children had significantly higher concentrations of blood free radical than that of normal children. No significant difference was observed in serotonin concentration between the two groups. Our results suggest a possible role of increased toxic mineral and free radical, both of which may be relevant to the pathophysiology of autism in children with developmental delay.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.6
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• pp.806-811
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• 2002

A 90 d study was designed to investigate the effects of rumen undegradable protein (RUP) and a mixture of Cu, Zn and Mn proteinate (CZMP) on milk yield and composition and ovarian functions during rainy months. Twenty four Holstein${\times}$ indigenous cows in their 2nd and 3rd lactation were randomly allocated to total mixed rations (TMR) containing soy bean meal (SBM) as a source of rumen degradable protein (RDP), SBM plus CZMP, and formalin treated SBM (FSBM) as a source of RUP. Maximum and minimum temperature humidity index during the experimental period were 83.6-84.7 and 75.4-76.1. There were no differences (p>0.05) in intakes of dry matter, crude protein and net energy and in contents of butterfat, lactose and minerals. Cows on TMR containing FSBM not only lost less weight (-278, -467 and -433 g/d) with more intake of RUP (0.92, 0.58 and 0.59 kg/d) but also produced more milk (19.27, 18.23 and 18.13 kg/d) and 4% fat corrected milk (18.57, 17.57 and 17.51 kg/d) with more protein (3.06, 2.81 and 2.80%), solids-not-fat (8.69, 8.38 and 8.38%) and less milk urea N (9.3, 15.4 and 15.0 mg/dl) compared with those on TMR containing SBM and SBM+CZMP, respectively (p<0.01). However, cows on TMR containing SBM and SBM+CZMP did not differ in these respects (p>0.05). Whereas incidence of cystic ovaries at 20 and 90 d pospartum was less (p<0.01) in cows on TMR containing SBM+CZMP (37.3 and 12.5%) than those on TMR containing SBM (62.5 and 25%), it was nil for cows on TMR containing FSBM. Cows in all three group differed (p<0.01) from each other for the recurrence of first observed estrus with those on TMR containing FSBM having least days (22, 36 and 47 d) compared with their counterpart on TMR containing SBM+CZMP and SBM, repectively. The results suggest that RUP is one of the limiting factors affecting milk yield and its composition and ovarian functions during early lactation of dairy cows in the tropics.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.4
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• pp.607-615
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• 2018

Objective: This study was conducted to isolate the cellulolytic microorganism from the rumen of Holstein steers and characterize endoglucanase gene (Cel5A) from the isolated microorganism. Methods: To isolate anaerobic microbes having endoglucanase, rumen fluid was obtained from Holstein steers fed roughage diet. The isolated anaerobic bacteria had 98% similarity with Eubacterium cellulosolvens (E. cellulosolvens) Ce2 (Accession number: AB163733). The Cel5A from isolated E. cellulolsovens sp. was cloned using the published genome sequence and expressed through the Escherichia coli BL21. Results: The maximum activity of recombinant Cel5A (rCel5A) was observed at $50^{\circ}C$ and pH 4.0. The enzyme was constant at the temperature range of $20^{\circ}C$ to $40^{\circ}C$ but also, at the pH range of 3 to 9. The metal ions including $Ca^{2+}$, $K^+$, $Ni^{2+}$,$Mg^{2+}$, and $Fe^{2+}$ increased the endoglucanase activity but the addition of $Mn^{2+}$, $Cu^{2+}$, and $Zn^{2+}$ decreased. The Km and Vmax value of rCel5A were 14.05 mg/mL and $45.66{\mu}mol/min/mg$. Turnover number, Kcat and catalytic efficiency, Kcat/Km values of rCel5A was $96.69(s^{-1})$ and 6.88 (mL/mg/s), respectively. Conclusion: Our results indicated that rCel5A of E. cellulosolvens isolated from Holstein steers had a broad pH range with high stability under various conditions, which might be one of the beneficial characteristics of this enzyme for possible industrial application.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.4
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• pp.588-596
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• 2020

Objective: The objective of this study was to investigate the effects of low doses of organic trace minerals (iron, copper, manganese, and zinc) on productive performance, egg quality, yolk and tissue mineral retention, and fecal mineral excretion of laying hens during the late laying period. Methods: A total of 405 healthy hens (HY-Line White, 50-week-old) were randomly divided into 3 treatments, with 9 replicates per treatment and 15 birds per replicate. The dietary treatments included feeding a basal diet + inorganic trace minerals at commercial levels (CON), a basal diet + inorganic trace minerals at 1/3 commercial levels (ITM), and a basal diet + proteinated trace minerals at 1/3 commercial levels (TRT). The trial lasted for 56 days. Results: Compared to CON, ITM decreased (p<0.05) egg production, daily egg mass, albumen height, eggshell strength, yolk Fe concentration, serum alkaline phosphatase activity and total protein, and increased (p<0.05) egg loss and feed to egg ratio. Whereas with productive performance, egg quality, yolk mineral retention, and serum indices there were no differences (p>0.05) between CON and TRT. The concentrations of Fe and Mn in the tissue and tibia were changed notably in ITM relative to CON and TRT. Both ITM and TRT reduced (p<0.05) fecal mineral excretion compared to CON. Conclusion: These results indicate that dietary supplementation of low-dose organic trace minerals reduced fecal mineral excretion without negatively impacting hen performance and egg quality.

• Korean Journal of Materials Research
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• v.9 no.8
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• pp.792-797
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• 1999

The 8mol.%Y$_2$$O_3$-$ZrO_2$mainly employed as an electrolyte of solid oxide fuel cells(SOFCs) shows excellent electrical properties but has a weakness in the mechanical properties. Since the electrolyte of SOFCs requires both good electrical and mechanical properties, this study was conducted to meet both requirements. The electrolyte thin films were produced on the LSM(cathode material) substrate of a cell and Si wafer. Four electrolyte film types of single layer and the multiple layer, consisting of 3-YSZ(3mol.%$Y_2$$O_3$) with excellent mechanical properties and 8-YSZ with the excellent electric conduction, were produced by electron beam coating technology. Ther crystal structure and the mechanical properties were also analysed. As the results of the study, the 3-YSZ thin film turned out to be in the tetragonal, partially monoclinic phase, while the 8-YSZ thin film showed the cubic phase. The residual stress in the multiple layer was lower than that of the single layer. The microhardness of the multiple layer was similar to that of the existing 8-YSZ single layer both before and after annealing treatment.

• The Korean Journal of Physiology
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• v.26 no.1
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• pp.55-68
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• 1992

The effects of changes in extracellular $Na^+\;and\;Ca^+$ concentration on the membrane potential and contractility were studied in the antral circular muscle of guinea pig stomach in order to elucidate the existence and the nature of $Na^+/Ca^{2+}$ exchange mechanism. All experiments were performed in tris buffered Tyrode solution which was aerated with 100% $O_2$ and kept at $35^{\circ}C.$ The treatment of $10^{-5}$ ouabain was performed to induce intracellular $Na^+$ loading prior to the start of experiment. The results were as follows: 1. $Na^+$-free Tyrode or high $Ca^{2+}$-Tyrode solution hyperpolarized the membrane potential and induced contracture. The time course of contracture was similar to that of change in membrane potential. 2. The degree of hyperpolarization and the amplitude of contracture decreased in accordance with the increase of extracellular $Na^+$ concentration. 3. $Na^+$-free contracture was developed even after blocking the influence of intrinsic nerves by the pretreatment with atropine, guanethidine and TTX. 4. $Ca^{2+}$-channel blockers(D-600 or $Mn^{2+}$) and the blocker of intracellular $Ca^{2+}$ release from sarcoplasmic reticulum(ryanodine) did not suppress the development of $Na^+$-free contracture. And also, dinitrophenol had no effect on $Na^+$-free contracture. 5. Dose-response relationship between extracellular $Na^+$ concentrations and the magnitude of contractures showed a sigmoid pattern. The slope of straight line from Hill plot was 2.7. 6. In parallel with the increase of extracellular $Ca^{2+}$ concentration, the amplitude of contracture increased dose dependently and was maximum at 8 mM $Ca^{2+}$-Tyrode solution. 7. The relationship between extracellular $Ca^{2+}$ concentrations and the magnitude of contractures showed hyperbolic pattern. The slope of straight line from Hill plot was 1.1. From the above results, it is suggested that $Na^+/Ca^{2+}$ exchange mechanism exists in the antral circular muscle of guinea pig stomach and this mechanism affects the membrane potential electrogenically.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.2
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• pp.146-158
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• 2010

In order to evaluate the characteristics of sediments and pollution by organic matter and metallic elements in intertidal sediments along the southwestern coast of Korea, we measured various geochemical parameters, including the mean grain size (Mz), water content (WC), ignition loss (IL), chemical oxygen demand (COD), acid volatile sulfide (AVS), and metallic elements (Al, Fe, Cu, Pb, Zn, Cd, Cr, Mn, Hg, As), in intertidal surface sediments. The Mz of the surface sediments ranged from 2.1 to 8.3$\phi$, indicating that the surface sediments consist of various sedimentary facies, such as sand, slightly gravelly mud, sandy mud, and silt. The IL and COD in surface sediment ranged from 0.8 to 5.5% (mean $2.9\pm1.2%$) and from 3.9 to $13.8\;mgO_2/g{\cdot}dry$ (mean $8.5\pm2.6\;mgO_2/g{\cdot}dry$), respectively, which were lower than the values for surface sediment in areas near fish and shellfish farms or industrial complexes. No AVS was detected at any sampling station, despite various sedimentary facies. Most of metallic elements in surface sediments showed relatively good positive correlations with Mz and IL, which imply that the concentrations of metallic elements are mainly controlled by grain size and the organic matter content. The concentrations of metallic elements, except As, at some stations were considerably lower than those in the Sediment Quality Guideline (Effect Range Low, ERL) proposed by the National Oceanic and Atmospheric Administration (NOAA) in the United States. Similarly, the geoaccumulation index (Igeo) class indicated that pollution by metallic elements in intertidal surface sediment, except As, was moderate or non-existent. Our results imply that the intertidal surface sediments along the southwestern coast of Korea are not polluted by organic matter and metallic elements and are healthy for benthic organisms.

• Journal of Microbiology and Biotechnology
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• v.20 no.3
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• pp.518-524
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• 2010

A mannanase gene (man26B) was obtained from a sea bacterium, Paenibacillus sp. BME-14, through the constructed genomic library and inverse PCR. The gene of man26B had an open reading frame of 1,428 bp that encoded a peptide of 475- amino acid residues with a calculated molecular mass of 53 kDa. Man26B possessed two domains, a carbohydrate binding module (CBM) belonging to family 6 and a family 26 catalytic domain (CD) of glycosyl hydrolases, which showed the highest homology to Cel44C of P. polymyxa (60% identity). The optimum pH and temperature for enzymatic activity of Man26B were 4.5 and $60^{\circ}C$, respectively. The activity of Man26B was not affected by $Mg^{2+}$ and $Co^{2+}$, but was inhibited by $Hg^{2+},\;Ca^{2+},\;Cu^{2+},\;Mn^{2+},\;K^+,\;Na^+$, and $\beta$-mercaptoethanol, and slightly enhanced by $Pb^{2+}$ and $Zn^{2+}$. EDTA did not affect the activity of Man26B, which indicates that it does not require divalent ions to function. Man26B showed a high specific activity for LBG and konjac glucomannan, with $K_m,\;V_{max}$, and $k_{cat}$ values of 3.80 mg/ml, 91.70 ${\mu}mol$/min/mg protein, and 77.08/s, respectively, being observed when LBG was the substrate. Furthermore, deletion of the CBM6 domain increased the enzyme stability while enabling it to retain 80% and 60% of its initial activity after treatment at $80^{\circ}C$ and $90^{\circ}C$ for 30 min, respectively. This finding will be useful in industrial applications of Man26B, because of the harsh circumstances associated with such processes.