• Korean Journal of Soil Science and Fertilizer
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• v.38 no.4
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• pp.202-210
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• 2005

Since understanding on spatial variability of a field is essential to pursue precision agricultural technology, a field study for field variability and variable rate fertilization of nitrogen in a direct seeding paddy was attempted. Variable rate application of nitrogen was designed with soil test, and field application was tested in a direct seeding paddy in the Kimje, Jeonbuk, Korea. The grid samples of soil was collected from the field of which unit size was 35 m by 112 m on February before irrigating of the field. Soil organic matter, available phosphate and silicate, and extractable potassium were analyzed. Variable rate fertilizer recommendation maps of nitrogen for high yielding, HY, and low input sustainable agriculture, LISA, were derived based on the soil analysis. Direct seeding of rice was performed for variable rate treatment, VRT, for the experimental plot in 2001 and 2002, and so did for three volunteer farmers' field in 2003. Yield mapping was performed by harvesting. Economic feasibility of direct seeding of rice by variable rate fertilization was evaluated. Though increased yield of variable rate application and benefit of reducing fertilizer use and environmental impact, the cost for soil test exceeded the total reduced fertilizer cost.

• Clinical and Experimental Reproductive Medicine
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• v.26 no.2
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• pp.171-178
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• 1999

The follicular fluid (FF) of ovary contains various biological active products which affected on the growth of follicles and the fertilization of oocyte in physiological reproductive process of mammals. This study was designed to determine the effects of human FF on fertilization of oocyte and embryonal development in vitro culture. The FF was prepared as clear without blood contamination by needle aspiration from mature follicles of human at the time of oocytes retrieval for in vitro fertilization (IVF). As the medium for culture in vitro of embryonal cells, human tubal fluid (HTF) supplemented with follicular fluids at concentrations of 10%, 40% and pure FF were used. These effects were compared to control group of cultured embryos in HTF supplemented with 0.4% BSA (bovine serum albumin). For IVF, 64 eggs in control group, 67 eggs in 10% FF, 57 eggs in 40% FF and 64 eggs in pure FF were respectively allocated. And the rates of fertilization were almost similar in all groups as resulting 82.81% in control, 85.07% in 10% FF, 87.71% in 40% FF and 81.25% in pure FF. On the examination for embryonal cleavage from fertilized eggs, the rates of developing to 4 cell stage was similar in all groups, as results 98.11% in control, 98.27% in 10% FF and 98% in 40% FF but 78.84% in pure FF. And the rates of developing to 8-16 cell stage were significantly reduced as 44% in 40% FF and 44.23% in pure FF (p<0.05) compare to 71.69% in control media. As likewise, the rates of developing to morular stage were also significantly reduced to 36% (p<0.05) and 21.15% (p<0.01) respectively in 40% FF and pure FF. And the rates to blastocystic stage of embryo was lowest as 7.69% in pure FF (Table 1). The quality of embryonal cells on cleavage to the 8-16 cell stage was poorer, higher concentrations of FF. The rates of grade 1 in pure FF, as 23.07%, was lowest compare to those of other groups, in which the rates of grade 1 in control, 10% FF and 40% FF were 58.49%, 47.36% and 34% respectively. And on the contrary, the rate of grade 4 in pure FF was highest as 23.07%, while those were 5.66% in control, 8.77% in 10% FF and 20% in 40% FF (Table 2). On the viability of embryos, the rate of embryonal cell death was more rise, at the higher concentrations as well as longer exposure in the follicular fluid. At 48 hours after in vitro culture of embryos, the rate of survival embryos in pure FF was markedly lowered as 44.23%, compare to that of control (p<0.05). But there was not significant difference between the rates of survival embryos in each group beside the pure FF, which the rates were 77.35% in control, 70.17% in 10% FF and 60% in 40% FF respectively. And at 72 hours after in vitro culture, the rates of survival embryos were also significantly dropped to 21.15% in pure and 36% in 40% at concentration of FF compare to 62.26% in control (p<0.05, p<0.01). Finally, the rate of embryonal death at 96 hours after in vitro culture was highest as 82.69% in pure FF among all groups which those were 35.84 in control, 56.14% in 10% FF and 64% in 40% FF respectively (Fig. 1, 2, 3). In conclusion, this study suggests that the FF has no effects, in particular, to the in vitro fertilization of oocytes but exerted a bad effect to the cleavage, quality and viability of the embryonal cells during in vitro culture. However, the FF is harmful on embryonal development at conditions in higher concentration and especially on the embryos after $8{\sim}16$ cell stage.

• Journal of fish pathology
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• v.20 no.3
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• pp.257-267
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• 2007

The hypo-salinity effects on fertilized eggs, embryos and larvae were investigated in olive flounder (Paralichthys olivaceus) obtained from hatcheries in Cheju-Island, Yeosu and Chungnam. Those were treated to eight concentration; 0, 3.4, 6.7, 10.1, 13.4, 20.2, 27.4 and 33.6 ‰. It was not discrepancy in the survival rate and hatching success rate of fertilized embryos obtained from different regions. Also, in the larvae, the regional difference was not appeared. The survival rate and hatching ability of embryos significantly diminished in the lower groups than 13.4 ‰ compared to 33.6 ‰. After fertilization, namely embryos are tolerant of a wide range of salinity (13.4 - 33.6 ‰). Reduced salinity induced an increase of the malformed embryo and larvae including various deformities; irregular embryos membrane (or yolk sac depression), fin erosion and swim bladder inflation in the flounder embryo. The hatching success of embryos was significantly reduced in lower salinity than 13.4 ‰. Notably, the reduction of larval survival rate significantly was observed in ≤10.1 ‰ treated groups with the same manner of survival rates of the embryos. Additionally, olive flounder was found to be adequate model for measuring external impulses because there are no the regional differences.

• Journal of Plant Biology
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• v.13 no.2
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• pp.21-31
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• 1970

The rice variety, Nongkwang was used in two factorial experiments with the combination of 15 kg and 20 kg of N per 10 a, 3 levels of P2O5 (0, 4 and 8 kg per 10 a) and 4 levels of potash(0, 2, 4 and 8 kg per 10 a) in the reclaimed soil areas containing 0.48% on the average salt content throughout the year(0.67% at the end of April). The absorption of N, K and Ca was accelerated by increased N applications. The absorption of P itself was not enhanced by the increased application of P2O5 but the absorption of K2O reduced the absorption of Mg was affected. The increased application of K2O reduced the absorption of Si and seemed to increase the content of carbohydrate in the rice plants. Twenty kg of N and 4kg of P2O5 per 10 a produced satisfactory yields of rough rice, potash applications are ineffective in this experiment on rice grain production.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.1187-1193
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• 2012

Water control is mainly one of the key factors that can affect nitrous oxide ($N_2O$) emissions from soils. This study was undertaken to determine the effect of intermittent drainage compared to continuous flooding (conventional water regime) on $N_2O$ emission to global warming potential (GWP) with NPK (standard cultivation practice), NPK+Straw, and PK fertilizations. Nitrous oxide emission rates were collected twice a week using a closed chamber method. With continuous flooding, nitrogen (N) application increased $N_2O$ emission by 106.6% ($0.64kg\;ha^{-1}$ in NPK) with respect to the PK treatment ($0.31kg\;ha^{-1}$), and straw addition to NPK enhanced 148.3% of seasonal $N_2O$ flux ($0.77kg\;ha^{-1}$ in NPK+Straw). Although seasonal $N_2O$ emission slightly increased by 16.1-42.9% with intermittent irrigation, its seasonal $CH_4$ emission drastically reduced at 43.5-52.8% resulting in a lower GWP at 48.9-58.5% with respect to that of continuously flooded treatments ($4.51Mg\;CO_2\;ha^{-1}$, PK; $7.60Mg\;CO_2\;ha^{-1}$, NPK; $14.55Mg\;CO_2\;ha^{-1}$, NPK+Straw). Rice yield, at similar fertilization with the continuously-flooded rice field, was not affected by intermittent irrigation. Conclusively, intermittent irrigation can be very effective and a rational soil management strategy to mitigate GWP with considering rice productivity in a temperate paddy rice field like Korea.

• Journal of Embryo Transfer
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• v.29 no.2
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• pp.133-139
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• 2014

$K^+$ channels are involved in the regulation of a variety of physiological functions, including proliferation, apoptosis and differentiation, in mammalian cells. Our previous study demonstrated that the blockage of $K^+$ channels inhibits mouse early embryonic development. This study was designed to identify the effect of $K^+$ channels during bovine embryonic development. $K^+$ channel blockers (tetraethylammonium (TEA), $BaCl_2$, quinine, ruthenium red and fluoxetine) were added to the culture medium during in vitro fertilization (IVF) for 6 h to first identify the short-term effect of these chemicals. Among $K^+$ channel blockers, fluoxetine, which is used as a selective serotonin reuptake inhibitor, significantly increased the blastocyst formation rate by approximately 6% when compared to control. During the in vitro maturation (IVM) of immature oocytes and the in vitro culture (IVC) of embryos, the oocytes and embryos were exposed to fluoxetine for either a short-term (6 h) or a long-term (24 h) to compare the embryonic development in response to exposure time. The 6 h exposure to fluoxetine during IVM did not affect the blastocyst formation rate, but the rate of blastocyst formation was reduced after the 24 h exposure. On the other hand, embryonic development increased approximately 10% in both groups of embryos exposed to fluoxetine for 6 and 24 h during IVC. Taken together, fluoxetine treatment during IVF and IVC, but not IVM, enhances bovine embryonic development. These results suggest that fluoxetine-modulated signals in oocytes and embryos could be an important factor towards enhancing bovine embryonic development.

• Korean Journal of Animal Reproduction
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• v.20 no.2
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• pp.163-170
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• 1996

The effect of several potential antioxidants and amino acids were examined as a means of increasing the development of in vitro matured and in vitro fertilized oocytes into morulae or blastocysts. Bovine embryos developed to the 2~8 cell stage after in vitro fertilization were cultured for 5 to 6 days at 39$^{\circ}C$ in CR1aa containing varing concentraton of the antioxidants and amino acid in a gas phase consisting of 5% CO2, high humidified air. At 5~6 days, embryo developments were reduced, and embryos were fixed and stained with Hochest 33342 DNA stain to facilitate counting of cells. In experiment 1, the proportion of embryos developed to morulae and blastocysts in CR1aa containing 1mM, 2.5mM taurine (22.6% and 20.4%) was slightly higher than those of 0, 5 and 10mM Taurine (5.7, 5.7 and 3.9%, P<0.05). In experiment 2, addition of glutathione did not improve blastocyst development (P>0.05). In experiment 3, concentations of superoxide dismutase(SOD) ranging from 300 to 1,000 U did not affect the propotion of embryos developing into blastocysts (P>0.05). In experiment 4, addition of 250 U catalase(38.5%) was slighty higher than those of 0, 500 and 1,000U. In experiment 5, the proportion of embryo developed beyond morula stage in CR1aa with taurine plus EDTA was slighty higher than other treatments(15.7, 26.0 and 29.2%), there were no significantly increases in cell number among treatments(P>0.05). These results are indicating that antioxidants and amino acids can increase the proportion of embryos that develop into morulae and blastocysts, but did not increas in cell number of blastocysts.

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2002.11a
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• pp.84-84
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• 2002

The advantages of the OPS techniques(Vajta G et al, Mol Reprod Dev 51: 53-58,1998) give 1) high survival rates of various types of eggs, 2) quick and simple process, 3) inexpensive equipment and reduced chilling injury. The efficiency of IVM/IVF technique in the porcine species is relatively lower than that obtained in other species such as ruminants. Two experiments were designed to investigate the effects of in-vitro fertilization of porcine oocytes matures using different OPS protocol for chilling and warming of vitrification. Porcine oocytes from ovaries collected at abattoir were matured for 44 hours in TCM199 Earle's salt supplemental with pyruvate, pff, L-cysteine, hormones and gentamycin. Oocytes were denuded and fertilized with frozen boar semen by common method. Porcine embryos produced routinely by in-vitro culture system of NCSU23 medium. The vitrification and the warming were conducted by OPS method with the glass micropipette instead of straw vessels and modified the protocol of G.Vajta(1999). In Exp 1, Chilling/Warming:Holding Medium(HM)+EG+DMSO/HM +sucrose Medium(SM) at 39$^{\circ}C$ warm stage. In Exp 2, : PBS+CS+EG+Ficoll+ Trehalose/PBS+Trehalose at 25$^{\circ}C$ stage. Filling, freezing, packing, thawing out and further culturing were performed to follow the basic protocol of G Vajta. During IVM-lVC and post-warming, fertilization parameter and developmental potential were compared to and statistically analysed. It was not significantly different from Exp 1 and Exp 2 but 25$^{\circ}C$ of stage was slightly higher on the morula/blastocyst forming rate and better atmosphere for worker than that at 39$^{\circ}C$ stage.

• Development and Reproduction
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• v.15 no.1
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• pp.31-39
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• 2011

Change in intracellular $Ca^{2+}$-concentration ($[Ca^{2+}]_i$) is an essential event for egg activation and further development. $Ca^{2+}$ ion is originated from intracellular $Ca^{2+}$-store via inositol 1,4,5-triphosphate receptor and/or $Ca^{2+}$ influx via $Ca^{2+}$ channel. This study was performed to investigate whether changes in $Ca^{2+}$/calmodulin dependent protein kinase II (CaM KII) activity affect $Ca^{2+}$ influx during artificial egg activation with ethanol using $Ca^{2+}$ monitoring system and whole-cell patch clamp technique. Under $Ca^{2+}$ ion-omitted condition, $Ca^{2+}$-oscillation was stopped within 30 min post microinjection of porcine sperm factor, and ethanol-induced $Ca^{2+}$ increase was reduced. To investigate the role of CaM KII known as an integrator of $Ca^{2+}$- oscillation during mammalian egg fertilization, CaM KII activity was tested with a specific inhibitor KN-93. In the eggs treated with KN-93, ethanol failed to induce egg activation. In addition, KN-93 inhibited inward $Ca^{2+}$ current ($I_{Ca}$) in a time-dependent manner in whole-cell configuration. Immunostaining data showed that the voltage-dependent $Ca^{2+}$ channels were distributed along the plasma membrane of mouse egg and 2-cell embryo. From these results, we suggest that $Ca^{2+}$ influx during fertilization might be controlled by CaM KII activity.

• Journal of The Korean Society of Grassland and Forage Science
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• v.17 no.1
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• pp.43-50
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• 1997

The aim of the study is to describe the fate and transformation of nitrogen in grassland ecosystems. Field experiments were conducted using sandyloam soil under variabling conditions: Zen, fertilization, reduced slurry application(l20kg N $ha^{-1}\;yr^{-1}$), usual sluny application (240 kg N $ha^{-1}\;yr^{-1}$).Soil water samples were gathered with 120cm ceramic cups with initial pressure of 0.5 bar. Samples were collected twice a month and analysed for NO, colormetrically. Percolation was calculated as the difference between precipitation and potential evapotranspiration, and leaching as the product of percolation and nitrate content of the water h m the ceramic cups. The N$H_4$-N content in soil had no significant effect on slurry application, but high slurry application on grassland resulted in high N$O_3$-N content in soil. The NO, concentration in soil water was remarkably variable during the year. The average N$O_3$, concentration during experiment became the lowest(8.5 mg/e ) without slurry application and highest with 240kOa cattle sluny(25.3 mg4 ). For each of the three different amounts of cattle sluny applied (0, 120, and 240kOa), the amount of N$O_3$-N leached per year were 12, 23 and 29kg/ha respectively. On grassland under the climatic conditions of Allgau showed enormous nitrate leaching, which has a p a t potential of polluting the ground water. The high pool of mineral N in the soil are the source for N$O_3$ leaching. The leaching of N$O_3$ cannot be avoided completely, but minimized by optimizing N fertilization rate.