• Applied Microscopy
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• 제44권3호
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• pp.96-99
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• 2014

Study on the egg envelope of an endemic Korean freshwater fish, Coreoleuciscus splendidus was carried out by light and scanning electron microscopes during its spawning season. The egg envelope on the entire egg is filled with plenty of long cylinder-like villi before and after fertilization. The fertilized eggs consist of two regions, the attaching and non-attaching parts to stick to the substrates. The villi covering the fertilized eggs have three kinds of villi in its length: 1) normal- sized villi of an average of $10.6{\mu}m$ on the non-attachment part; 2) longer and more slender villi over about $20{\mu}m$ on the attachment part, at least being two times longer than those of the non-attachment; and 3) shorter villi under about $5.0{\mu}m$ around the micropyle, with half the size of the non-attachment villi. The micropyle rotated in a counter-clockwise direction with five pieces of the ridges.

• Clinical and Experimental Reproductive Medicine
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• 제40권4호
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• pp.143-147
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• 2013

Oocyte in vitro maturation (IVM) is an assisted reproductive technology in which oocytes are retrieved from the antral follicles of unstimulated or minimally stimulated ovaries. IVM of human oocytes has emerged as a promising procedure. This new technology has advantages over controlled ovarian stimulation such as reduction of costs, simplicity, and elimination of ovarian hyperstimulation syndrome. By elimination or reduction of gonadotropin stimulation, IVM offers eligible infertile couples a safe and convenient form of treatment, and IVM outcomes are currently comparable in safety and efficacy to those of conventional in vitro fertilization. IVM has been applied mainly in patients with polycystic ovary syndrome or ultrasound-only polycystic ovaries, but with time, the indications for IVM have expanded to other uncommon situations such as fertility preservation, as well as to normal responders. In this review, the current clinical experiences with IVM will be described.

• The Korean Journal of Zoology
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• 제39권2호
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• pp.182-189
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• 1996

It has been known that spermatozoa should obtain their fertilizing ability through capacitation and acrosome reaction, and that in these processes of fertilization, Ca2+ platys an important role for their conjugation. Therefore the present study has been designed in order to clarify the effect of fluctuation of the media Ca2+ level and the intracellular concentration of the spermatozoa on the acrosomes. During the incubation of spermatozoa, a considerable fluctuation in the media Ca2+ level has been observed after the BSA administration and the media concentration of Ca2+. It is deduced that these fluctuation rates may have an effect on the acrosome reaction. The fluctuation of K+ flux has been observed in accordance with the incubation period over time, and it's concentration seems to be closely related with the acrosomal reaction. The respiratory exchange rate (RERI of the spermatozoa is kept more regular in the BSA and Cacl2 administration groups than the non-administration group. Based on the experimental findings, it is possible to deduce a hypothesis from these findings that physiological activities of the acrosome reaction are not functionally related to the media Ca2+ level and the intracellular influx of Ca2+ concentration, although Ca2+ platys an important role as a stimulating factor in the acrosome reaction.

• Korean Journal of Agricultural Science
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• 제49권2호
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• pp.307-316
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• 2022

The misuse of pesticides has resulted in environmental pollution, which directly or indirectly affects all life on earth. Chlorpyrifos is a chlorinated organophosphorus pesticide that is commonly used in agriculture. The aim of this study was to investigate the effects of chlorpyrifos on the fertilization function of boar spermatozoa. Sperm samples from boars were subjected to varying concentrations of chlorpyrifos from 10 to 200 µM for two incubation periods, 30 min or 2 hrs. The boar spermatozoa were then evaluated for motility, motion kinematics, viability, acrosome integrity, chromatin stability, and generation of intracellular reactive oxygen species (ROS). There was a significant percentage reduction in sperm motility and motion kinematic parameters after both incubation periods (p < 0.05). The proportion of viable spermatozoa decreased after incubation for 30 min and 2 hrs in a dose-dependent manner (p < 0.05). A significantly lower percentage of normal acrosomes was observed in spermatozoa exposed to 200 µM chlorpyrifos over both incubation periods, compared to the controls. The damage to sperm DNA was significantly higher when the exposure time to chlorpyrifos was longer. There was a significant increase in the ROS levels in spermatozoa incubated with chlorpyrifos for 2 hrs (p < 0.05). From the results of the present study, it is concluded that direct exposure of boar spermatozoa to chlorpyrifos altered boar sperm characteristics, suggesting potential toxicity that may affect the male reproductive function.

• The Korean Journal of Malacology
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• 제21권2호
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• pp.95-105
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• 2005

Gonadosomatic index, reproductive cycle, spermatogenesis and first sexual maturity of Chlamys farreri were investigated by cytological and histological observations, from January 1998 to December 1999. The gonadosomatic index (GSI) rapidly increased in April and reached a maximum in May when seawater temperature rapidly increase. Then the GSI gradually decreased from June to August when spawning occur. Accordingly, monthly changes in the GSI in males coincide with the reproductive cycle. The spermatozoon of Chlamys farreri is the primitive type found in external fertilization species. The head of the spermatozoon is approximately $2.75{\mu}m$ in length including the acrosome measuring about $0.50{\mu}m$ in length, and its tail was approximately $20{\mu}m$, the axoneme of the tail flagellum consists of nine pairs of microtubules at the periphery and a pair at the center. Five spherical mitochondria around the centriole (the satellite body) appear in the middle piece of the sperm. The spawning period was from June to August and the main spawning occurs from July to August when seawater temperatures are greater than $20^{\circ}C$ The reproductive cycle of this species can be categorized into five successive stages; early active stage (January to March), late active stage (March to April), ripe stage (April to August), partially spawned stage (June to August), and spent/inactive stage (August to January). Over 50% of male scallops attained first sexual maturity between 50.0 and 60.0 mm in shell height, and 100% of those over 60.0 mm in shell height achieved maturity. Accordingly, we assume that male individuals begin reproduction at three years of age.

• Journal of Embryo Transfer
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• 제10권3호
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• pp.251-256
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• 1995

This study was experimented that developmental effects of bovine in vitro fertilized embryos by coculture system and supplementation of energy materials into simple media. With the ovaries from slaughter house in vitro maturation by 24h, in vitro fertilization was performed with sperms collected by Percoll gradient method. Fertilized embryos were cocultured in 15% FCS+CZB medium with BOEC(bovine oviductal epithelial cell), GCM (granulosa cell monolayer) and MEFC(mouse embryonic fihrohlast cell). And also in this study, there was trying to improve the early developmental rate of embryos by addition of concentration-controlled Na-pyruvate, D-glucose which were used as energy sources into CZB medium. In vitro developmental rate was confirmed by the cleavage rate of 48h post-IVF and the embryo development rate at 240h culture. In the coculture system BOEC had 20.0% of blastocysts rate, which was higher than that of other coculture systems. To determine the optimum concentration for early embryo developmental rate rapidly, through the gradient of concentrations of Na-pyruvate and D-glucose, we focused on the cleavage rate at 48h and blastocysts rate at 240h. In case of Na-pyruvate, cleavage rate and developmental rate over 3-cell were lower at the concentration of 1.OOrnM than the other treatment concentrations, otherwise the blastocysts rate was higher as 23.2% than the others. That result showed that as like reported group which had higher develop-mental rate over 3-cell was also higher to the blastocysts rate. In case of D-glucose, there was no effects through the concentration changes. It was the result of this study for which the use of BOEC coculture system and 1.OOmM Na-pyruvate as an energy source had an effect upon embryo development.

• KOREAN JOURNAL OF CROP SCIENCE
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• 제47권2호
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• pp.127-131
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• 2002

Critical nitrogen concentration (Nc), which is defined as the minimum % N in shoots required to maintain the maximum growth rate of top dry weight (W) at any time, was determined for rice plant. Using two rice varietal groups, japonica varieties and an indica $\times$ japonica "Dasanbyeo", 18 data points fulfilling the statistical criteria for determining Nc were obtained through eight N-fertilization experiments over two years at Suwon (37$^{\circ}$16'N), Korea. Nc dilution curve for each variety was obtained by fitting the Nc-W relationship to power function. However, The critical nitrogen curves for the two variety groups were not different statistically. Thus, a Nc dilution curve was fitted for the Nc data points pooled over the two variety groups and proposed in rice as: Nc=4.08, where W＜1.73 t h $a^{-1}$ , Nc=5.197 $W^{0.425}$3/ ($R^2$=0.964), where 1.73 t h $a^{-1}$ ＜W＜12 t h $a^{-l}$. The Nc for W＜1.73 t h $a^{-l}$ were estimated as a constant value of 4.08%, the mean value of the maximum N concentration for N-limiting condition and the minimum N concentration for N non-limiting condition. The model for Nc is applicable to diagnosing the nitrogen nutrition status during the rice growth period from emergence to heading stage. The Nc curve well discriminated the 144 data points between the N limiting and the N non-limiting groups regardless of varieties, cultural methods, and years.-limiting groups regardless of varieties, cultural methods, and years.

• Korean Journal of Agricultural and Forest Meteorology
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• 제14권4호
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• pp.207-221
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• 2012

Air temperature in Korea has increased by $1.5^{\circ}C$ over the last 100 years, which is nearly twice the global average rate during the same period. Moreover, it is projected that such change in temperature will continue in the 21st century. The objective of this study was to evaluate the potential impacts of future climate change on the rice production and adaptation methods in Korea. Climate data for the baseline (1971~2000) and the three future climate (2011~2040, 2041~2070, and 2071~2100) at fifty six sites in South Korea under IPCC SRES A1B scenario were used as the input to the rice crop model ORYZA2000. Six experimental schemes were carried out to evaluate the combined effects of climatic warming, $CO_2$ fertilization, and cropping season on rice production. We found that the average production in 2071~2100 would decrease by 23%, 27%, and 29% for early, middle, and middle-late rice maturing type, respectively, when cropping seasons were fixed. In contrast, predicted yield reduction was ~0%, 6%, and 7%, for early, middle, and middle-late rice maturing type, respectively, when cropping seasons were changed. Analysis of variation suggested that climatic warming, $CO_2$ fertilization, cropping season, and rice maturing type contributed 60, 10, 12, and 2% of rice yield, respectively. In addition, regression analysis suggested 14~46 and 53~86% of variations in rice yield were explained by grain number and filled grain ratio, respectively, when cropping season was fixed. On the other hand, 46~78 and 22~53% of variations were explained respectively with changing cropping season. It was projected that sterility caused by high temperature would have no effect on rice yield. As a result, rice yield reduction in the future climate in Korea would resulted from low filled grain ratio due to high growing temperature during grain-filling period because the $CO_2$ fertilization was insufficient to negate the negative effect of climatic warming. However, adjusting cropping seasons to future climate change may alleviate the rice production reduction by minimizing negative effect of climatic warming without altering positive effect of $CO_2$ fertilization, which improves weather condition during the grain-filling period.

• Clinical and Experimental Reproductive Medicine
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• 제34권3호
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• pp.173-178
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• 2007

Objective: To compare the outcome of twin pregnancies after in-vitro fertilization (IVF) with that of spontaneously conceived twins. Methods: We analyzed 146 twins retrospectively, who had been delivered between January 2000 and July 2005. After reviewing their obstetric medical records, 72 twins conceived with IVF (IVF group) and 51 spontaneously conceived twins (spontaneous group), whose gestational age was over 24 weeks, were recruited for this study. Results: There were no significant statistical differences of demographic features such as maternal age, gestational age and fetal weight between the two groups. However, the risk of pregnancy-induced hypertension (PIH) and gestational diabetes (G-DM) had significantly increased in the group of IVF (OR 2.59; 95% CI 1.01$\sim$6.66). The risk of fetal weight discordancy rate (>20%) and fetal-sex homology rate in IVF group were decreased (OR 0.37; 95% CI 0.14$\sim$0.96, OR 0.45; 95% CI 0.21$\sim$0.99). Conclusion: In this comparative study, maternal PIH and G-DM risks of IVF group are higher than that of spontaneous group. But, fetal-weight discordancy risk and fetal-sex homology rate were lower in IVF group.

• Asian Journal of Turfgrass Science
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• 제25권2호
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• pp.217-222
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• 2011

Professional turfgrass applicators have reduced or eliminated phosphorus from their fertilization programs based on the assumption that soil phosphorus levels are supplying adequate amounts of phosphorus to the turfgrass. The previous researchers found that there were no P effects for turfgrass growth especially for mature turf. No effects may result from high P level in heavy thatch layer. The research was conducted for one year to investigate the effects of phosphorus fertilization programs on turfgrass performance, and monitor soil and plant tissue nutrient levels to determine the impact of the programs on a newly seeded Kentucky bluegrass. The nitrogen treatments were 20, 30 and $40g\;m^{-2}\;yr^{-1}$. The low, medium, and high nitrogen treatments were applied over 2, 4 and 6 applications, respectively. Nitrogen was applied using a formulation containing 30% of slow and 70% of fast release nitrogen sources that are representative of typical home lawn fertilizers. The phosphorus treatments were 0, 10 and $20g\;m^{-2}\;yr^{-1}$. Phosphorus was applied according to the application schedule for the nitrogen treatments. Kentucky bluegrass was seeded in May, 2010. The thickness of thatch layer was less than 1 cm and the first treatment was applied to Kentucky bluegrass in April, 2011. The low N rate treatment had acceptable color and quality ratings without high clipping yields. The high N rate treatment consistently had the highest color and quality ratings but also had very high clipping yields in comparison to the low and medium N rate treatments. Although there are significant differences in tissue P, Overall, there was no effect of phosphorus on color, quality, or clipping weights.