• Journal of Microbiology and Biotechnology
• /
• v.29 no.1
• /
• pp.105-113
• /
• 2019

Although siderophore compounds are mainly biosynthesized as a response to iron deficiency in the environment, they also bind with other metals. A few studies have been conducted on the impact of heavy metals on the siderophore-mediated iron uptake by microbiome. Here, we investigated siderophore production by a variety of rhizosphere fungi under different concentrations of $Zn^{2+}$ ion. These strains were specifically isolated from the rhizosphere of Panax ginseng (Korean ginseng). The siderophore production of isolated fungi was investigated with chrome azurol S (CAS) assay liquid media amended with different concentrations of $Zn^{2+}$ (50 to $250{\mu}g/ml$). The percentage of siderophore units was quantified using the ultra-violet (UV) irradiation method. The results indicated that high concentrations of $Zn^{2+}$ ion increase the production of siderophore in iron-limited cultures. Maximum siderophore production by the fungal strains was detected at $Zn^{2+}$ ion concentration of $150{\mu}g/ml$ except for Mortierella sp., which had the highest siderophore production at $200{\mu}g/ml$. One potent siderophore-producing strain (Penicillium sp. JJHO) was strongly influenced by the presence of $Zn^{2+}$ ions and showed high identity to P. commune (100% using 18S-rRNA sequencing). The purified siderophores of the Penicillium sp. JJHO strain were chemically identified using UV, Fourier-transform infrared spectroscopy (FTIR), and matrix-assisted laser desorption/ionization time-of-flight mass spectrometer (MALDI-TOF-MS) spectra.

• Journal of Biomedical Engineering Research
• /
• v.43 no.6
• /
• pp.369-374
• /
• 2022

Purpose: Focused ultrasound is an emerging technology for treating the brain locally in a noninvasive manner. In this study, we have investigated the influence of skull properties on simulating transcranial pressure field. Methods: A 3D computational model of transcranial focused ultrasound was constructed using female and male CT data to solve for intracranial pressure. For heterogeneous model, the acoustic properties were calculated from CT Hounsfield units based on a porosity. The homogeneous model assigned constant acoustic properties for the single-layered skull. Results: A computational model was validated against empirical data. The homogeneous models were then compared with the heterogeneous model, resulted in 10.87% and 7.19% differences in peak pressure for female and male models respectively. For the focal volume, homogeneous model demonstrated more than 94% overlap compared with the heterogeneous model. Conclusion: Homogeneous model can be constructed using MR images that are commonly used for the segmentation of the skull. We propose the possibility of the homogeneous model for the simulating transcranial pressure field owing to comparable focal volume between homogeneous model and heterogeneous model.

• Korean Journal of Food Science and Technology
• /
• v.16 no.3
• /
• pp.267-272
• /
• 1984

${\beta}-Fructofuranosidase$ was immobilized covalently on the oxidized microbial wall of a Penicillium spp. 'PS-8', which is totally different from the conventional whole cell immobilization in concept. The immobilization of ${\beta}-fructofuranosidase$ by a series of treatments; oxidation of microbial cells with sodium metaperiodate, enzyme loading on the oxidized cells, extrusion, and crosslinking induced by glutaradehyde, were carried out. The final product had a good mechanical strength and showed 26% of the applied enzyme activity. The specific activity was 750 units per g of the dry cell product. The immobilized enzyme showed the kinetic parameters as follows; optimum pH at 5, optimum temperature at $55^{\circ}C$, activation energy of 19 kJ $mol^{-1}$, and apparent Km of 55 mM.

• Journal of The Korean Association For Science Education
• /
• v.31 no.5
• /
• pp.680-693
• /
• 2011

In conceptual ecology, a concept does not exist independently but occupies an ecological niche in ecological environment. Among many biological concepts, genetic concepts are connected to several units including the genetics unit, and within the genetics unit the concepts of sub-areas are highly dependent on one another. For this reason, we analyzed conceptual diversity and conceptual proximity of genetic concepts through the ecological niche approach. For this purpose, we surveyed 995 9th graders. The areas covered in the survey were four genetic concepts: gene, chromosome, mitosis, and meiosis. The questionnaire presented biological concepts or terms related to each area, and the respondent marked the relevance between the presented biological concepts or terms and each area on a scale of 1~30 points. With 9th grade students, we analyzed the change of genetic concepts through class by the ecological niche approach. Through class, the total number of concepts increased in all of the areas, and the increase was smallest in the area of meiosis followed by mitosis, chromosome and gene. Relative density decreased with increases in the number of concepts. The conceptual diversity index also increased through class in all of the areas, and the increase was smallest in the area of meiosis followed by mitosis, chromosome and gene. In addition, difference in the relative density of concepts was reduced after class, and difference in the score of relevance was also reduced and consequently similarity among concepts increased. From these results were drawn conclusions as follows: First, through class, the conceptual diversity of genetic concepts increased. Second, through class, the conceptual proximity of genetic concepts increased.

• Journal of The Korean Association For Science Education
• /
• v.10 no.1
• /
• pp.17-31
• /
• 1990

The purpose of this study is to make a comparative analysis of the educational bojective, organization, contents, teaching and evaluation of the biological curriculum in high school of Korea and the United States. The results are summarized as follows: 1. In case of the educational objectives, both Korea and the United States emphasize the importance of the process of inquiry, experimentation and observation. Particularily, great emphasis is placed upon the human centered curriculum by reinforcing the relationships between the nature and human being. 2. In regard to the educational organization, eleven credit units(Science I: 5 credits, Biology: 6 credits) is allocated in Korea, and ten credit unit, in the United States. Both of Korea and United Stats designate the biology as elective course. But the science I course is designated as required in Korea 3. This study have been analyzed the educational contents of the two countries within the framwork of the basic concepts and essential informations contained in the curriculum. Results of the analysis as follow: The educational contents have less quantity and lower level in Korea than in the United States. And interrelations among the other curricula are not well considered in the curriculum of Korea/ On the other hands, interrelations among the oter curricula are fully considered and the purpose for emphasizing the importance of the process of inquiry course is well considered in the United States. The themes are stressed on "Structure and Function" (34.5%), "Genetic continuty" (21.3%), "Diversity and Unit" (14.2%) and "Regulation and Homeostasis" (10.3%) in Korea, and in the United States "Structure and Function" (27.3%), "Diversity and Unity" (25.6%), "Genetic continuty" (17.9%) and "Organism and Environment" (9.3%). 4. Regarding the educational guidance, both of Korea and the United States emphasis the interrelation of the basic concepts and principles within the total framwork. Also observation and experimentation, safety education, interest of students, life dignity, pretection of nature, social biology are reguired being paid special attentions. 5. In case of evaluation, both of Korea and the United States are the same in all of methods of evaluation. But the United States is grest stressed on reading and writing.

• Microbiology and Biotechnology Letters
• /
• v.37 no.3
• /
• pp.204-212
• /
• 2009

A strain producing ${\alpha}$-galactosidase and ${\beta}$-glucosidase was isolated from Kimchi. The isolated strain was identified as Weissella cibaria by 16S rDNA analysis and designated as Weissella cibaria K-M1-4. The enzyme activity of ${\alpha}$-galactosidase and ${\beta}$-glucosidase reached the maximum in the soy medium at $37^{\circ}C$ for 24 hr. The enzymes were purified by ethanol fractionation, DEAE sepharose fast flow, and sephacryl S-100HR column chromatography. ${\alpha}$-Galactosidase specific activity was shown by 576 Units/mg protein and the yield was 3.5% of the total activity of crude extracts. ${\beta}$-glucosidase specific activity was shown by 480 Units/mg protein and the yield was 2.9% of the total activity of crude extracts. The optimum temperature for ${\alpha}$-galactosidase was $60^{\circ}C$ and 43% of its original activity remained when it was treated at $80^{\circ}C$ for 30 min. For ${\alpha}$-galactosidase shows the optimum pH of 8.0 and is fairly stable between pH5.0 and pH9.0. The enzyme activity was increased in the presence of $Fe^{2+}$ and $Cu^{2+}$. The value of Km and Vmax for the enzyme were 0.98 mM and $1.81{\mu}$mole/min, respectively. The ${\beta}$-glucosidase has the optimum temperature of $50^{\circ}C$ and 46% of its original activity remained when it was treated at $80^{\circ}C$ for 30min. Its optimum pH of 7.0 and is fairly stable between pH5.0 and pH9.0. The enzyme activity was increased in the presence of $Fe^{2+},\;Co^{2+}$ and $Cu^{2+}$. The value of Km and Vmax for the enzyme were 1.24 mM and $6.81{\mu}$mole/min, respectively.

• Nutrition Research and Practice
• /
• v.6 no.2
• /
• pp.155-161
• /
• 2012

Excessive oxidative stress and abnormal blood lipids may cause chronic diseases. This risk can be reduced by consuming an antioxidant- and fiber-rich vegetarian diet. We compared biomarkers of oxidative stress, antioxidant capacity, and lipid profiles of sex- and age-matched long-term vegetarians and omnivores in Korea. Forty-five vegetarians (23 men and 22 women; mean age, $49.5{\pm}5.3$ years), who had maintained a vegetarian diet for a minimum of 15 years, and 30 omnivores (15 men and 15 women; mean age, $48.9{\pm}3.6$ years) participated in this study. Their 1-day, 24-h recall, and 2-day dietary records were analyzed. Oxidative stress was measured by the levels of diacron reactive oxygen metabolites (d-ROM). Antioxidant status was determined by the biological antioxidant potential (BAP) and levels of endogenous antioxidant enzymes such as superoxide dismutase, catalase, and glutathione peroxidase. We observed that vegetarians had a significantly lower body fat percentage ($21.6{\pm}6.4%$) than that of omnivores ($25.4{\pm}4.6%$; $P$ < 0.004). d-ROM levels were significantly lower in vegetarians than those in omnivores ($331.82{\pm}77.96$ and $375.80{\pm}67.26$ Carratelli units; $P$ < 0.011). Additionally, total cholesterol levels in the vegetarians and omnivores were $173.73{\pm}31.42$ mg/dL and $193.17{\pm}37.89$ mg/dL, respectively ($P$ < 0.018). Low-density lipoprotein cholesterol was $101.36{\pm}23.57$ mg/dL and $120.60{\pm}34.62$ mg/dL ($P$ < 0.005) in the vegetarians and omnivores, respectively, indicating that vegetarians had significantly lower lipid levels. Thus, oxidative stress, body fat, and cholesterol levels were lower in long-term vegetarians than those in omnivores.

• BMB Reports
• /
• v.37 no.4
• /
• pp.408-415
• /
• 2004

The expression of the Paenibacillus sp. A11 cyclodextrinase (CDase) gene using the pUC 18 vector in Escherichia coli JM 109 resulted in the formation of an insoluble CDase protein in the cell debris in addition to a soluble CDase protein in the cytoplasm. Unlike the expression in Paenibacillus sp. A11, CDase was primarily observed in cytoplasm. However, by adding 0.5 M sorbitol as an osmolyte, the formation of insoluble CDase was prevented while a three-fold increase in cytoplasmic CDase activity was achieved after a 24 h-induction. The recombinant CDase protein was purified to approximately 14-fold with a 31% recovery to a specific activity of 141 units/mg protein by 40-60% ammonium sulfate precipitation, DEAE-Toyopearl 650 M, and Phenyl Sepharose CL-4B chromatography. It was homogeneous by non-denaturing and SDS-PAGE. The enzyme was a single polypeptide with a molecular weight of 80 kDa, as determined by gel filtration and SDS-PAGE. It showed the highest activity at pH 7.0 and $40^{\circ}C$. The catalytic efficiency ($k_{cat}/K_m$) values for $\alpha$-, $\beta$-, and $\gamma$-CD were $3.0{\times}10^5$, $8.8{\times}10^5$, and $5.5{\times}10^5\;M^{-1}\;min^{-1}$, respectively. The enzyme hydrolyzed CDs and linear maltooligosaccharides to yield maltose and glucose with less amounts of maltotriose and maltotetraose. The rates of hydrolysis for polysaccharides, soluble starch, and pullulan were very low. The cloned CDase was strongly inactivated by N-bromosuccinimide and diethylpyrocarbonate, but activated by dithiothreitol. A comparison of the biochemical properties of the CDases from Paenibacillus sp. A11 and E. coli transformant (pJK 555) indicates that they were almost identical.

• Journal of Korean Society of Forest Science
• /
• v.96 no.6
• /
• pp.724-729
• /
• 2007

Due to the low productivity in timber harvesting, economic values of forest resources have been rarely validated in Korea. Since the Korea Forest Service provided a statistic of the timber assets for the survey of the 4th National Accounting (1998), no more statistics or measurements have been provided. Further, it becomes an issue that there is no clear standard to classify timber assets into produced or non-produced assets. In this research, we intended to provide a reasonable standard that enables one to classify timber assets either in produced or non-produced assets. For this purpose, articles in the '1993 System of National Accounts (SNA)', which presented definitions and scopes of biological assets, were scanned. The articles related to timber assets in the Korean version of SNA were compared with those in the original version of SNA that were proposed by UN. The results show that the Korean version of SNA seems to have much emphasis on natural occurrence or plantation for the classification standard, while its original version rather focus on the existence of direct control, responsibility, and management by institutional units. According to the original version of SNA, naturally occurring assets, which were basically classified into non-produced assets, were treated as being cultivated and classified into the produced asset when they (or their growth) were under the direct control, responsibility, and management of institutional units. Therefore, a guidance was presented to renew the Korean version of SNA and to innovate the classification standards for timber assets.

• Korean Journal of Ichthyology
• /
• v.29 no.3
• /
• pp.218-223
• /
• 2017

Using both light and scanning electron microscopies, it was investigated on the visual cells as well as the eyes of Macropodus ocellatus (Pisces, Osphronemidae). This species had a circular lens and yellowish cornea. The eyes had $3.5{\pm}0.2mm$ which is $31.1{\pm}3.0%$ in a percentage of eye diameter relative to head length. The retina ($158.2{\pm}10.6{\mu}m$) was built of several layers, including the visual cell layer which consists of three types of cells: single cons ($27.8{\pm}1.6{\mu}m$) and equal double cone ($33.9{\pm}3.7{\mu}m$), and large rods ($57.3{\pm}1.3{\mu}m$). The visual cell layer then was classified into the correct pattern. All visual cells were clearly distinguished from two parts (inner and outer segments). The elongated rod cells were extend to the bottom of the retinal pigment epithelium. In scanning electron microscopy, the outer segment links to inner segment by so-called calyceal piles. The M. ocellatus single and double cones appearance form a flower-petal arrangement, which is a regular mosaic pattern that contains quadrilateral units by four double cones surrounding a single cone.