Research Institute for Agriculture and Life science

Seoul National, South Korea

Research Institute for Agriculture and Life science

Seoul National, South Korea
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Oh S.-T.,Intelligent Textile System Research Center | Oh S.-T.,Research Institute for Agriculture and Life science | Oh S.-T.,University of Suwon | Kim W.-R.,Intelligent Textile System Research Center | And 9 more authors.
Fibers and Polymers | Year: 2011

Polyurethane (PU) foam was combined with protein drug-loaded pH-sensitive alginate-bentonite hydrogel for wound dressings. Alginate is a linear copolymer composed of 1-4-linked β-D-mannuronic acid (M) and its c-5-epimer α-Lguluronic acid (G). The amount of (M) and (G) and their sequential distribution are varied depending on the alginate source. Soluble sodium alginate can become a hydrogel when cross-linked with divalent cations and has widespread applications in the food, drink, pharmaceutical and bioengineering industries. Recently, it has been also proposed as a biomaterial for drug delivery systems. Bentonites are the natural inorganic polymers consisting of a large proportion of expandable clay minerals with a three-layer structure such as montmorillonite, beidellite, nontronite, etc. They are important adjutants and supports for medical products, and they have many useful physicochemical, mechanical, and biological properties such as absence of toxicity, indifference to other raw materials, sorption, swelling, and complex formation properties. Alginate-bentonite hydrogels were prepared at concentration ratios of 10/0, 7/3, 5/5, 3/7. PU foams were prepared using hydrophilic polyols. We investigated the controlled release of a protein drug from PU foam combined with alginate-bentonite hydrogel at different pH values of 4.2, 5.2, 7.2, 8.2. The mechanical properties and cytotoxicity tests of this foam were also studied. © 2011 The Korean Fiber Society and Springer Netherlands.

Kim M.,Korea Food Research Institute | Kim M.,Research Institute for Agriculture and Life science | Kim M.,Seoul National University | Ryu S.,Korea Food Research Institute | And 2 more authors.
Molecular Microbiology | Year: 2012

As natural killers of bacteria, bacteriophages have forced bacteria to develop a variety of defence mechanisms. The alteration of host receptors is one of the most common bacterial defence strategies against phage infection, which completely blocks phage attachment but comes at a potential fitness cost to the bacteria. Here, we report the cost-free, transient emergence of phage resistance in Salmonella enterica subspecies enterica serovar Typhimurium through a phase-variable modification of the O-antigen. Phage SPC35 typically requires BtuB as a host receptor but also uses the Salmonella O12-antigen as an adsorption-assisting apparatus for the successful infection of S.Typhimurium. The α-1,4-glucosylation of galactose residues in the O12-antigen by phase variably expressed O-antigen glucosylating genes, designated the LT 2 gtrABC1 cluster, blocks the adsorption-assisting function of the O12-antigen. Consequently, it confers transient SPC35 resistance to Salmonella without any mutations to the btuB gene. This temporal switch-off of phage adsorption through phase-variable antigenic modification may be widespread among Gram-negative bacteria-phage systems. © 2012 Blackwell Publishing Ltd.

Kim H.,Research Institute for Agriculture and Life science | Lee T.,Research Institute for Agriculture and Life science | Park W.,Research Institute for Agriculture and Life science | Lee J.W.,Horse Industry Research Center | And 20 more authors.
DNA Research | Year: 2013

The modern horse (Equus caballus) is the product of over 50 million yrs of evolution. The athletic abilities of the horse have been enhanced during the past 6000 yrs under domestication. Therefore, the horse serves as a valuable model to understand the physiology and molecular mechanisms of adaptive responses to exercise. The structure and function of skeletal muscle show remarkable plasticity to the physical and metabolic challenges following exercise. Here, we reveal an evolutionary layer of responsiveness to exercise-stress in the skeletal muscle of the racing horse. We analysed differentially expressed genes and their co-expression networks in a large-scale RNA-sequence dataset comparing expression before and after exercise. By estimating genome-wide dN/dS ratios using six mammalian genomes, and FST and iHS using re-sequencing data derived from 20 horses, we were able to peel back the evolutionary layers of adaptations to exercise-stress in the horse. We found that the oldest and thickest layer (dN/dS) consists of system-wide tissue and organ adaptations. We further find that, during the period of horse domestication, the older layer (FST) is mainly responsible for adaptations to inflammation and energy metabolism, and the most recent layer (iHS) for neurological system process, cell adhesion, and proteolysis. © The Author 2013. Published by Oxford University Press on behalf of Kazusa DNA Research Institute.

Ha J.-W.,Seoul National University | Kim H.-J.,Seoul National University | Kim H.-J.,Research Institute for Agriculture and Life science
Agricultural Engineering International: CIGR Journal | Year: 2015

A front-end loader for agricultural purposes is the most commonly used implement for agri-tractors in Korea. As it is operated to raise, lower and carry various objects in a farming field, it bringsa large amount of stress to a tractor, causing vibrations and often leading to a mechanical breakdown. These high stresses are observed at the starting and ending points of operation, that is, the points at which the highest acceleration and deceleration occur. To reduce the sudden change of the speed, soft-start & end operation were tested with an electrohydraulic directional valve, which has a built-in ramp time spool control function. This valve was controlled by SAE-J1939 associated messages via CAN bus. This shock-absorbing system contains three electronic control unit(ECUs): a loader ECU for receiving and transmitting loader position data, a joystick ECU to convert a lever position that is constantly being changed by an operator into CAN messages, and a valve ECU to regenerate all messages into the J1939 standard to be understood by the electrohydraulic directional valve. By sensing the loader position and speed, the ramp activation point wasdetermined. As expected, applying ramp time control to the front-end loader control system proved to be effective for reducing the shock level, in contrast to that of the conventional control using a hydraulic manual valve. © 2015, Int. Comm. of Agricultural and Biosystems Engineering. All rights reserved.

Kim H.-C.,Research Institute for Agriculture and Life science | Lee C.-G.,Research Institute for Agriculture and Life science | Park J.-A.,Research Institute for Agriculture and Life science | Kim S.-B.,Research Institute for Agriculture and Life science
Journal of Environmental Science and Health - Part A Toxic/Hazardous Substances and Environmental Engineering | Year: 2010

This study investigated the adsorption of arsenite [As(III)] and arsenate [As(V)] to iron-impregnated granular activated carbon (Fe-GAC), focusing on the effects of bacteria on arsenic removal. Characteristics of Fe-GAC were analyzed using field emission scanning electron microscopy along with energy dispersive X-ray spectrometry. Batch experiments were performed under various experimental conditions to determine the adsorption of As(III) and As(V) to Fe-GAC in the absence and presence of bacteria (Enterococcus faecalis, Escherichia coli, or Bacillus subtilis). In addition, biosorption of As(III) and As(V) to bacteria was observed with batch experiments. Experimental results showed that Fe-GAC was characterized by mosaic-like deposition layers separated by interspacing on the surface. Iron impregnation increased the removal of As(III) and As(V) in GAC. Biosorption experiments indicated that a small amount of As(V) adsorbed to bacteria while no adsorption of As(III) was observed. This phenomenon can be attributed to interactions of anionic As(V) with positively-charged amine groups present on bacterial surfaces. Results also showed that the influence of bacteria on arsenic removal in Fe-GAC was not eminent in our experimental conditions even though bacteria could occupy surface adsorption sites on iron (hydr)oxides. This study demonstrated that hindrance effects of bacteria on arsenic adsorption to the surfaces of Fe-GAC were minimal.

Song W.,Korea Environment Institute KEI | Kim E.,Korea Environment Institute KEI | Lee D.,Seoul National University | Lee D.,Research Institute for Agriculture and Life science | And 2 more authors.
Ecological Modelling | Year: 2013

Species distribution modeling is one of the most effective habitat analysis methods for wildlife conservation. We evaluated the sensitivity of species distribution modeling to different grain sizes and extent sizes from 30m to 4950m using maximum entropy (MaxEnt) modeling. The grain size represents a unit for analysis, whereas the extent size defines the scope of the analysis in a way that reflects the environmental data for the area in which the species of interest occurs. We compared the resulting suitability indexes and habitat areas based on two approaches. The first approach increases the extent size for a fixed grain size. The second approach increases the grain size and the extent size by equal amounts. The suitability index based on the first approach (R2=0.34) was greater than the suitability index based on the second approach (R2=0.89). The first approach was fitted to a logarithmic function with a critical point at approximately 0.5km, converging to about 0.76. In contrast, the second approach showed a linear decrease to values less than 0.5. The distribution of habitat area found with the second method (R2=0.87) was broader than that found with the first method (R2=0.63). The relationship between the extent size and the landscape index of the first method can be displayed as a power-law graph with a critical point of 0.5km. The method of expanding extent size has greater accuracy, although the time that it requires for data processing is long. The results of this study suggest that the maximum grain size should be approximately 1.5km. If the grain size is greater than 1.5km, the accuracy of the habitat suitability index decreases below 0.6, and the predicted habitat suitability increases dramatically. © 2012 Elsevier B.V.

Lim J.S.,Seoul National University | Ki C.S.,Amore Pacific | Kim J.W.,Seoul National University | Lee K.G.,Korea Advanced Institute of Science and Technology | And 4 more authors.
Biopolymers | Year: 2012

In this study we investigated the blend electrospinning of poly(Ïμ-caprolactone) (PCL) and silk fibroin (SF) to improve the biodegradability and biocompatibility of PCL-based nanofibrous scaffolds. Optimal conditions to fabricate PCL/SF (50/50) blend nanofiber were established for electrospinning using formic acid as a cosolvent and three-dimensional (3D) PCL/SF blend nanofibrous scaffolds were prepared by a modified electrospinning process using methanol coagulation bath. The physical properties of 2D PCL/SF blend nanofiber mats and 3D highly porous blend nanofibrous scaffolds were measured and compared. To evaluate cytocompatibility of the 3D blend scaffolds as compared to 3D PCL nanofibrous scaffold, normal human dermal fibroblasts were cultured. It is concluded that biodegradability and cytocompatibility could be improved for the 3D highly porous PCL/SF (50/50) blend nanofibrous scaffold prepared by blending PCL with SF in electrospinning. In addition to the blending of PCL and SF, the 3D structure and high porosity of electrospun nanofiber assemblies may also be important factors for enhancing the performance of scaffolds. © 2012 Wiley Periodicals, Inc.

Islam M.A.,Seoul National University | Islam M.A.,Research Institute for Agriculture and Life science | Islam M.A.,Center for Food and Bioconvergence | Firdous J.,Seoul National University | And 8 more authors.
International Journal of Nanomedicine | Year: 2012

Chitosan, a natural biodegradable polymer, is of great interest in biomedical research due to its excellent properties including bioavailability, nontoxicity, high charge density, and mucoadhesivity, which creates immense potential for various pharmaceutical applications. It has gelling properties when it interacts with counterions such as sulfates or polyphosphates and when it crosslinks with glutaraldehyde. This characteristic facilitates its usefulness in the coating or entrapment of biochemicals, drugs, antigenic molecules as a vaccine candidate, and microorganisms. Therefore, chitosan together with the advance of nanotechnology can be effectively applied as a carrier system for vaccine delivery. In fact, chitosan microspheres have been studied as a promising carrier system for mucosal vaccination, especially via the oral and nasal route to induce enhanced immune responses. Moreover, the thiolated form of chitosan is of considerable interest due to its improved mucoadhesivity, permeability, stability, and controlled/extended release profile. This review describes the various methods used to design and synthesize chitosan microspheres and recent updates on their potential applications for oral and nasal delivery of vaccines. The potential use of thiolated chitosan microspheres as next-generation mucosal vaccine carriers is also discussed. © 2012 Islam et al, publisher and licensee Dove Medical Press Ltd.

Tran P.-T.,Seoul National University | Choi H.,Seoul National University | Kim S.-B.,Seoul National University | Lee H.-A.,Seoul National University | And 4 more authors.
Journal of Virological Methods | Year: 2014

Plant NBS-LRR genes are abundant and have been increasingly cloned from plant genomes. In this study, a method based on agroinfiltration and virus inoculation was developed for the simple and inexpensive screening of candidate R genes that confer a hypersensitive response to plant viruses. The well-characterized resistance genes Rx and N, which confer resistance to Potato virus X (PVX) and tobamovirus, respectively, were used to optimize a transient expression assay for detection of hypersensitive response in Nicotiana benthamiana. Infectious sap of PVX and Tobacco mosaic virus were used to induce hypersensitive response in Rx- and N-infiltrated leaves, respectively. The transient expression of the N gene induced local hypersensitive response upon infection of another tobamovirus, Pepper mild mottle virus, through both sap and transcript inoculation. When this method was used to screen 99 candidate R genes from pepper, an R gene that confers hypersensitive response to the potyvirus Pepper mottle virus was identified. The method will be useful for the identification of plant R genes that confer resistance to viruses. © 2014 Elsevier B.V.

Lee J.,Seoul National University | Ryu J.,Seoul National University | Youn H.J.,Seoul National University | Youn H.J.,Research Institute for Agriculture and Life science
Cellulose | Year: 2012

A conductive paper was made of cellulose fibers with a multilayer of polyethyleneimine (PEI) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and the factors to increase the conductivity of the paper were investigated. The adsorption amount and the structure of PEI and PEDOT:PSS multilayer was changed by controlling salt concentration and the number of layers, and inter-contact degree of fibers was controlled by calendering. The adsorption behavior of the polyelectrolytes onto cellulose was evaluated using a quartz crystal microbalance with dissipation monitoring, and the adsorption amount was quantitatively analyzed through Kjeldahl nitrogen analysis and an Inductively Coupled Plasma Optical Emission Spectrometer. The conductivity of the resultant paper was in the range of 10 -5-10 -4 S/cm without loss of paper strength. The conductivity of the paper increased when the multilayer was formed at low salt concentration and the conductive paper was calendered. It appeared that electron transfer by increased contact between PEDOT:PSS improved the conductivity of the paper. © 2012 Springer Science+Business Media B.V.

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