• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.1114-1119
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• 2012

This study was conducted to assess the microbial toxicity of ionic silver solution ($Ag^+N$) and silver nanoparticle suspension ($Ag^0NP$) based on the Microtox bioassay. In this test, the light inhibition of luminescent bacteria was measured after 15 and 30 min exposure to aqueous solutions and soils spiked with a dilution series of $Ag^+N$ and $Ag^0NP$. The resulting dose-response curves were used to derive effective concentration (EC25, $EC_{50}$, EC75) and effective dose ($ED_{25}$, $ED_{50}$, $ED_{75}$) that caused a 25, 50 and 75% inhibition of luminescence. In aqueous solutions, $EC_{50}$ value of $Ag^+N$ after 15 min exposure was determined to be < $2mg\;L^{-1}$ and remarkably lower than $EC_{50}$ value of $Ag^0NP$ with $251mg\;L^{-1}$. This revealed that $Ag^+N$ was more toxic to luminescent bacteria than $Ag^0NP$. In soil extracts, however, $ED_{50}$ value of $Ag^+N$ with 196 mg kg-1 was higher than $ED_{50}$ value of $Ag^0NP$ with $104mg\;kg^{-1}$, indicating less toxicity of $Ag^+N$ in soils. The reduced toxicity of $Ag^+N$ in soils can be attributed to a partial adsorption of ionic $Ag^+$ on soil colloids and humic acid as well as a partial formation of insoluble AgCl with NaCl of Microtox diluent. This resulted in lower concentration of active Ag in soil extracts obtained after 1 hour shaking with $Ag^+N$ than that spiked with $Ag^0NP$. With longer exposure time, EC and ED values of both $Ag^+N$ and $Ag^0NP$ decreased, so their toxicity increased. The toxic characteristics of silver nanomaterials were different depending on existing form of Ag ($Ag^+$, $Ag^0$), reaction medium (aqueous solution, soil), and exposure time.

• Parasites, Hosts and Diseases
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• v.28 no.3
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• pp.143-154
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• 1990

Observations were made on the differences of cell-mediated responses in mice of three infectiorl groups di여erently scheduled in their severity with pathogenic Acanthamoeba culbertseni. Infections were done by dropping $5{\;}{\mu}l$ saline suspension containing $3{\times}10^3,{\;}1{\times}10^4,{\;}or{\;}1{\times}10^5$ trophosoites, respectively. Amoebae were cultured anenically in CGV medium and inoculated into the right nasal cavity of CSH/HeJ mice aging around 6∼8 weeks, under the anesthesia by intraperitoneal injection of secobarbital. Delayed type hypersensitivity (DTH) responses in footpad and blastogenlc responses of mouse spleen cells using ($^3H$)-thymidine and the serum antibody titer were measured up to day 14 after infection, and natural killer cell activities were measured up to day, i after infection. The results obtained in this study were as follows: 1. The mice infected with $3{\times}10^3$ trophosoites showed mortality rate of 17%, and 345 in the mice infected with $1{\times}10^4$ trophozoites and 65% with $1{\times}10^5$ trophozoites. 2. In regard to DTH responses in all experimental groups, the level increased on day 7 and declined on day 14 after infection, but their differences could not be noted between infected and control groups. 3. The blastogenic responses of splenocytes treated with amoeba Iysates and lipopolysaccharides (LPS) showed no difference from the control group. The blastogenic responses of splenocytes treated with concanavalin A were declined significantly in the experimental group as compared with the control group, but the blastogenic responses of splenocytes treated with polyinosinic acid were not different from the control group. There was also no difference among three infected groups. 4. The cytotoxic activity of the natural killer cells was activated on day 1 after infection and declined to the level of control group on day 2 in all experimental groups. On day 5 after infection, the natural killer cell cytotoxicity was significantly suppressed as compared with the control groups. 5. The serum antibody titers of the infected mice increased after day 7, but there was no statistical difference between the three infected groups. In summary of the results, there was no difference in cell-mediated immune responses of three experimental groups scheduled with different infection intensities. But there was a significant difference in cell$.$mediated immune responses between infected and control mice. It is considered that cell-mediated immune responses should be involved in murine model infected with A. culbertsoni.

• The Korean Journal of Malacology
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• v.25 no.2
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• pp.161-171
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• 2009

The present study was performed to describe the influence of water temperature and salinity on filtration rates of the venus clam, Gomphina veneriformis, a suspension-feeding (filter-feeding) bivalve species. The calmswere collected from the eastern coastal area of Sokcho, Gangneung and Jumunjin at Kangwon-do, Korea, during December 2006 and May 2007. Isochrysis galbana (KMCC H-002) cells as food organisms were indoor-cultured by f/2 medium, and were used to measure the filtration rate of clam. Filtration rates of clam were measured by indirect method. Cell concentration of food organisms were determined by direct counting cells used the hemacytometer under the light microscope. The filtration rates of clams by water temperature sharply increased with temperatures up to $15^{\circ}C$ as optimum temperature and above this temperature, the filtration rates decreased exponentially. Venus clams showed very low filtration rates at low salinity (10-15 psu) and maximum values at high salinity (30-35 psu). Regardless of water temperature and salt change, 2-year class clams showed high filtration rates, but low in 4-year-class. Polynomial regression curves with water temperature were shifted to the left in low temperature region. Thermal coefficient $Q_{10}$ values showed much higher values at low temperature range than at high temperature range, too. These results indicate that the venus clam is more sensitive in cold water. Polynomial regression curves with salinity were shifted to the right in high saline region. According to this study, the venus clam Gomphina veneriformis, subtidal filter-feeding bivalve, was the stenothermal organism, inhabited mainly in low temperature and the stenohaline, in high saline waters.

• Korean Journal Plant Pathology
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• v.3 no.3
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• pp.180-186
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• 1987

Cell suspensions of two isolates of Pseudomonas syringae. PS8401 from sweet persimon and PS8402 from tea plant, were active in ice nucleation at -2.5 and $-3.8^{\circ}C$, respectively. Ice nucleation at those temperature was, using micropipette method, detected in suspensions ($10^8$ olony forming unit/ml of distilled water) of cells that had been grown on nutrient agar supplemented with $2.5\%$ glycerol. Using the same method, on the other hand, the freezing temperature of distilled water only was approx. $-21.8^{\circ}C$, and those of various plant saps including corn were lower than $-11.6^{\circ}C$. Corn seedlings sprayed with cell suspensions $(10^8\;cfu/ml)$ of nutrient broth) of PS8401 began to be damaged at $-2^{\circ}C$ and were almost completely damaged at $-4^{\circ}C$, whereas seedlings sprayed with nutrient broth only were not injured until the temperature down to $-9^{\circ}C$. Amounts of frost damage measured 48 hr after application of PS8401 suspensions increased as applied bacterial cell densities were increased. Ice-nucleation activity of the cell suspensions in vitro increased with increasing the number of cells in suspension. The activity also affected by growth-medium composition or growth-temperature. Ice nucleation thus occured at -4.0, -4.4 and $-7.2^{\circ}C$ in suspensions $(10^2\;cfu/ml)$ of PS8401 that had been grown at$25\%$ nutrient agar with $2.5\%$ glycerol, nutrient agar with $2.5\%$ glucose and nutrient agar only, respectively, and occured at -4.0 and $-7.6^{\circ}C$ in suspensions $(10^2\;cfu/ml)$ of PS8401 hat had been grown on nutrient agar with $2.5\%$ glycerol at $15\~25^{\circ}C$ and $30^{\circ}C$, respectively.

• Korean Journal of Poultry Science
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• v.41 no.4
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• pp.249-259
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• 2014

Cryopreserving cells which are maintaining their viability are the very complex process. This study has been carried out in order to find the effects of cryopreservation steps and freezing media on the rates of viability of cryopreserved chicken primordial germ cells (PGCs). PGCs obtained from the germinal gonade of 5.5~6 day (stage 28) chick embryos of Korean Ogye (KO) and Commercial breeds (C), using the MACS method were suspended in a freezing medium containing a freezing and protecting agents (e.g. dimethyl sulfoxide (DMSO), ethylene glycol (EG) and propylene glycol (PG)). Gonads were harvested from stage 28 chick embryos and pooled in groups of 5, 10, 15, 20E embryos, contributing gonads to the cell suspension. The gonadal cells, including PGCs, were then frozen in 1 of the following cryoprotectant treatments : 2.5%, 5%, 10%, 15% and 0% cryoprotectant (DMSO, EG, PG) as a control. Effects of exposure to slow freezing and vitrification, with different concentrations of the cryoprotectant solution, were examined. After vitrification and slow freezing, survival rates of the frozen-thawed PGCs from the 10% EG plus FBS treatment were 85.63%, and 66.14% (p<0.05), respectively. The viability of PGCs after freeze-thawing was significantly higher for 10% EG plus FBS treatment than for 10% PG + FBS treatment (p<0.05) (85.63% vs 66.81%) by vitrification. This study established a method for preserving chicken PGCs that enables systematic storage and labeling of cryopreserved PGCs in liquid ($LN_2$) at a germplasm repository and ease of entry into a data base. In the future, the importance for this new technology is that poultry lines can be conserved while work is being conducted on improving the production of germline chimeras.

• Journal of Periodontal and Implant Science
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• v.26 no.1
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• pp.1-26
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• 1996

This study was performed to estimate the effects of cultured bone cell inoculated on porous type hydroxyaptite for the regeneration of the artificial alveolar bone defect. In this experiment 3 beagle dogs were used, and each of them were divided into right and left mandible. Every surgical intervention were performed under the general anesthesia by using with intravenous injection of Pentobarbital sodium(30mg/Kg). To reduce the gingival bleeding during surgery, operative site was injected with Lidocaine hydrochloride(l:80,000 Epinephrine) as local anesthesia. After surgery experimental animal were feeded with soft dietl Mighty dog, Frisies Co., U.S.A.) for 1 weeks to avoid irritaion to soft tissue by food. 2 months before surgery both side of mandibular 1st premolar were extracted and bone chips from mandibular body were obtained from all animals. Bone cells were cultured from bone chips obtained from mandible with Dulbecco's Modified Essential Medium contained with 10% Fetal Bovine Serum under the conventional conditions. Porous type hydroxyapatite were immerse into the high concentrated cell suspension solution, and put 4 hours for attachin the cells on the surface of hydroxyapatite. Graft material were inserted on the artificial bone defect after 3 days of culture. Before insertion of cellinoculated graft material, scanning electronic microscopic observation were performed to confirm the attachment and spreading of cell on the hydroxyapatite surface. 3 artificial bone defects were made with bone trephine drill on the both side of mandible of the experimental animal. First defect was designed without insertion of graft material as negative control, second was filled with porous replamineform hydroxyapatite inoculated with cultured bone marrow cells as expermiental site, and third was filled with graft materials only as positive control. The size of every artificial bone defect was 3mm in diameter and 3mm in depth. After the every surgical intervention of animals, oral hygiene program were performed with 1.0% chlorhexidine digluconate. All of the animals were sacrificed at 2, 4, 6 weeks after surgery. For obtaining histological section, tissus were fixed in 10% Buffered formalin and decalcified with Planko - Rycho Solution for 72hr. Tissue embeding was performed in paraffin and cut parallel to the surface of mandibular body. Section in 8um thickness of tissue was done and stained with Hematoxylin - Eosin. All the specimens were observed under the light microscopy. The following results were obtained : 1. In the case of control site which has no graft material, less inflammatory cell infiltration and rapid new bone forming tendency were revealed compared with experimental groups. But bone surface were observed depression pattern on defect area because of soft tissue invasion into the artificial bone defect during the experimental period. 2. In the porous hydroxyapatite only group, inflammatory cell infiltration was prominet and dense connective tissue were encapsulated around grafted materials. osteoblastic activity in the early stage after surgery was low to compared with grafted with bone cells. 3. In the case of porous hydroxyapatite inoculated with bone cell, less inflammatory cell infiltration and rapid new bone formation activity was revealed than hydroxyapatite only group. Active new bone formation were observed in the early stage of control group. 4. The origin of new bone forming was revealed not from the center of defected area but from the surface of preexisting bony wall on every specimen. 5. In this experiment, osteoclastic cell was not found around grafted materials, and fibrovascular invasion into regions with no noticeable foreign body reaction. Conclusively, the cultured bone cell inoculated onto the porous hydroxyapatite may have an important role of regeneration of artificial bone defects of alveolar bone.

• KSBB Journal
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• v.21 no.4
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• pp.248-254
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• 2006

Animal cell culture industry has a large market and an exponential growth rate among biological industry field. Chines hamster ovary(CHO) cells are the most widely used cell lines for recombinant protein production. They can avoid infection from polio, herpes, hepatitis B, HIV, measles, adenovirus and etc. Moreover it is easy to transfection recombinant genes and possible to suspension culture. Serum free media is one of the most important factor of protein production. Because serum has problems. Serum is not defined the contents until now, it has a number of proteins, lipids, carbohydrates and unknown molecules that cause of risk involve in infection and high cost of product purification. CHO cell line cultured using serum free media were the basis of a very successful method to produce(glyco-)protein in mammalian cells, which are then used as pharmaceutical products. Also, the low protein content of the developed medium facilitates downstream processing and product purification. But non-adapted CHO cells have a limit of proliferation cultured using serum free media and it takes very long time to adapt non-adapted cells to serum free media. There are a number of causes of a limit of proliferation using serum free media. Absence of growth factors and growth stimulating molecules is a major factor of the reasons. It makes growth signals and moves cell cycle. And increase of cellular stress is another reason. It induces increase of intraceullar ROS concentration. The purpose of this study is about improvement of proliferation capacity of non-adapted CHO cells cultured using serum free media without adaptation process.

• Parasites, Hosts and Diseases
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• v.27 no.3
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• pp.177-186
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• 1989

Observations were made on the differences in cell-mediated immune responses in the mice infected with strongly pathogenic Naegleria fewleyi ITMAP 359, weakly pathogenic Naegzeria jadini 0400, or non.pathogenic Naegleria gruberi EGB, respectively. Variations in cell-mediated responses and changes in antibody titers according to the duration after infection wore noted. Infections were done by dropping $5{\;}{\mu}l$ saline suspension containing $10{\times}10^4$ trophozoites cultured Bxenically in the CGVS medium into the right nasal cavity of ICR mice aging about 6~7 weeks, under the anesthesia by intraperitoneal injection of'secobarbital. Following infection, delayed type hypersensitivity(DTH) iesponses in the footpad and blastogenic responses of the mouse spleen cells using [$^3H$]-thymidine were observed on the day 1, 4, 7, 10 and 14 after infection. For the preparation of amoeba Iysates, each of cultured trophosoites were homogenized with an ultrasonicator, and centrifugated at 20,000 g. The supernatants of amoeba Iysates were used as the mitogen'and antigen for ELISA. Confanavalin A(Con. A) and lipopolysaccharide(LPS) were also used as mitogens in the blastogenic response. 1. The mice infected with N, fowleri showed the mortality rate of 75.7%. The rate was 6.2% for the N. jadini infected group, while no dead mouse was observed for N. gruberi infections. 2. In regard to DTH responses in the H. fewleri infected mice, the level increased in com- parison to the control group but declined after 7 days. An increase was also noted for the JV. jadini group after 1 day, but gradual decreases were observed through the infection period. In addition, no difference was noted between the N. gruberi infected and control groups. 3. Concerning the blastogenic response of the splenocytes, it increased after 10 days in the experimental group of N, fcwleri infection, but the differences ware not statistically significant compared with control group. It was evident that N. jadini group was not different from control group either, while there was a tendency of decrease in SV. gruberi infected group. In regard to the blastogenic response of the splenocytes by LPS, it was found that the N. fowlgri, N. jadini and N. gruberi infected groups had no differences from the control group. 4. The serum antibody titer of N. fcwleri and N. jadini infected mice increased from the day 7 and 14 after infection respectively, while the N. gruberi infected mice showed no increase. In summary of the results, it was observed that there were differences in the cell-mediated immune responses and serum antibody titers in the mice infected with strongly pathogenic JV. fowleri, weakly pathogenic N. jadini, or non.pathogenic N. gruberi, respectively.

• Korean Journal of Organic Agriculture
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• v.25 no.2
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• pp.345-355
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• 2017

This study was conducted to evaluate rice seed disinfection efficacy of loess-sulfur for the suppression of Bakanae disease caused by Fusarium fujikuroi. Rice seeds were treated at different concentrations of loess-sulfur, soaking time and temperature, and combination of hot-water treatment. Rice cultivar, Shindongjin harvested from Bakanae disease-infested area in 2015, was used. Loess-sulfur was treated as follows; concentration of undiluted solution, 2%, 1% and 0.5%; soaking time of 24 and 48 hours; treatment temperature of $20^{\circ}C$ and $30^{\circ}C$; hot water treatment or not. Optimal conditions of rice seed disinfection were selected soaking time of 48 hours and the suspension of 0.5% and 1% loess-sulfur by investigating seed germination and isolation frequency of Fusarium spp. on Komada agar medium in vitro, and were established 3 disinfection conditions as hot water ($60^{\circ}C$, 10 min.) + 1% loess-sulfur ($20^{\circ}C$, 48 hours), 1% loess-sulfur only ($30^{\circ}C$, 48 hours) and 1% loess-sulfur only ($20^{\circ}C$, 48 hours) through additional test in greenhouse. Above 3 conditions were verified by rice seedling box and paddy field test in the way of investigating Bakanae diseased plants (%) and healthy plants (%). Consequently, most effective rice seed disinfection conditions on Bakanae disease were combination of hot water and 1% loess-sulfur and loess-sulfur only at $30^{\circ}C$. Furthermore, treatments with these conditions showed control value of 100% were maintained from seedling to the heading stage in the field. However, treatment of 1% loess-sulfur only at $20^{\circ}C$ showed low control value of 78.2% in paddy field. Hot water only treatment turned out to be an effective disinfection method when conducted thoroughly with $60^{\circ}C$, 10 min. However, it was thought additional soaking process with loess-sulfur after hot water treatment served more high control effect against Bakanae disease when rice seeds were disinfected on a large scale. This results expected rice seed disinfection with loess-sulfur were effectively and easily usable method if farmers had only one of either hot water-disinfector or seed-disinfector. In addition, loess-sulfur is well-known to farmers, simple to manufacture method and cheap.

• Korean journal of applied entomology
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• v.24 no.3 s.64
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• pp.117-121
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• 1985

Through the laboratory and vinyl house experiments, the effects of inoculum density, plant age and temperature on the incidence of Phytophthora crown rot of pepper (Capsicum annum L.) were investigated. The propagule survival was greater in the natural soil than in autoclaved soil within first 2 weeks when the sporangial suspension of the pathogenic fungus was incorporated into soil, thereafter the survivability reduced rapidly. The propagule was not detectable in 35 days by means of Papavizas selective medium neither in natural nor in autoclaved soil. At least 5 sporangia per gram soil were required to induce crown rot for 30 days old pepper seedlings. Further increase in inoculum concentration above this threshold level resulted in higher disease incidence and shorter incubation period. When the same amount of inoculum was infested, higher disease incidence was observed for younger plants until 3 weeks after inoculation. On the other hand after 4 weeks this tendency was not extended any more. Younger plants were recognized as having shorter incubation period upon infection, however, the days from first symptom appearance to complete death were not significantly different among differently aged seedlings. Exposure of inoculated pepper seedlings to $25^{\circ}C$ resulted in highest infection rates and followed by those to $30^{\circ}C\;and\;20^{\circ}C$ but no disease was found at $15^{\circ}C\;and\;35^{\circ}C$ for 10 days. When the plants previously incubated at different temperature for 10 days were moved to $25^{\circ}C$ room temperature, prior exposure to $20^{\circ}C\;and\;30^{\circ}C$ brought continuous disease development. Even those plants preincubated at $15^{\circ}C$ were diseased up to 50%. But the prior exposure to $35^{\circ}C$ induced no symptom developed, indicating no seedlings infected at all.