• Ocean and Polar Research
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• v.30 no.3
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• pp.347-349
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• 2008

A single juvenile of the jawfish Stalix toyoshio (24.0 mm standard length) was collected from the South Sea of Korea at a depth of 135 m during box-corer sampling. The specimen was characterized by the absence of stripes on both the body and vertical fins, well-developed cephalic pore systems, yellowish body and fins, six transversely-forked dorsal fin spines, and five mandibular pores. Here, we describe the specimen, which represents the first record of S. toyoshio from Korea and the second record from the northwestern Pacific.

• Ocean and Polar Research
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• v.26 no.4
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• pp.685-688
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• 2004

The morphology of the post-larva of Liopropoma japonicum of the family serranidae is described from one specimen collected off Jeju Island ($32^{\circ}42'N,\;127^{\circ}45'E$) on May 3, 2001. The body is laterally compressed and caudal peduncle deep at 19.4 mm BL. Anus locates at a vertical through posteriormost(8th) dorsal-fin spine. Dorsal fin rays were VIII, 14; anal fin rays III, 10; pectroal fin rays 16; pelvic fin rays I, 5. A caudal fin is rounded. Length of elongate second and third dorsal-fin spines are 499% and 423% of the body length, respectively. A series of 50 sensory pores on body is elongated to caudal fin. Head spination is well developed. Melanophores are moderately large and dense in the head, and are small and rare in teh neck. Being freshly collected, the body color is yellowish-red and tail is semitransparent. The head is yellowish-red and the brain is dark-red.

• Clinical and Experimental Reproductive Medicine
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• v.38 no.4
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• pp.234-237
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• 2011

Objective: During stimulated IVF cycles, up to 15% of oocytes are recovered as immature. The purpose of this study was to investigate the trend of oocyte maturity in repeated ovarian stimulation for IVF. Methods: One hundred forty-eight patients were selected who underwent two consecutive IVF cycles using same stimulation protocol during 2008 to 2010. Ovarian stimulation was performed with FSH and human menopausal gonadotropin and flexible GnRH antagonist protocol in both cycles. Oocyte maturity was assessed according to presence of germinal vesicle (GV) and the first polar body. Immature oocyte was defined as GV stage or metaphase I oocyte (GV breakdown with no visible polar body) and cultured up to 48 hours. If matured, they were fertilized with ICSI. Results: Percentages of immature oocytes were 30.8% and 32.9% ($p$=0.466) and IVM rates of immature oocytes were 36.2% and 25.7% ($p$=0.077), respectively. A significant correlation was noted between percentage of immature oocytes in the two cycles (R=0.178, $p$=0.03). Women with >40% immaturity in both cycles (n=21) showed lower fertilization rate of $in$ $vivo$ matured oocytes (56.4% vs. 72.0%, $p$=0.005) and lower pregnancy rate (19.0% vs. 27.1%, $p$=0.454) after the second cycle when compared with women with <40% immaturity (n=70). In both groups, female age, number of total retrieved oocyte and embryos transferred were similar. Conclusion: In repeated ovarian stimulation cycles for IVF, the immature oocyte tended to be retrieved repetitively in consecutive IVF cycles.

• Journal of Embryo Transfer
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• v.16 no.3
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• pp.223-231
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• 2001

The success of nuclear transplantation with mammalian oocytes depends critically on the potential of oocytes activation, which mainly caused to prevent the re-accumulation of maturation promoting factor (MPF). This study was conducted to compare the effect of combined treatment of lonomycin with a Hl-histone kinase inhibitor (dimethylaminopurine, DMAP) or cdc2 kinase inhibitor (sodium pyrophosphate, SPP) on activation of bovine oocytes. In vitro matured bovine oocytes with the first polar body (PB) and dense cytoplasm were assigned to 3 experimental groups. For activation treatment, oocytcs were exposed to 5 $\mu$M lonomycin for 5 min (Group 1), and followed by 1.9 mM dimethylaminopurine (DMAP) for 3 h (Group 2) or followed by 2 mM sodium pyrophosphate (SPP) for 3 h (Group 3). The activation effects in the three treatments and the control group (untreated) were judged by the extrusion of the second PB and formation of a pronucleus (PN). Differences among groups were analysed using one-way ANOVA after arc-sine transformation of proportional data. All three treatments led to high activation rates (90% to 95%), with significant difference from the control. However, the extrusion of the second PB and the rate of PN formation differed remarkably among treatments. In Group I and 3, about 95% of the oocytes had extruded the second polar body, but one PN had formed in a higher proportion of oocytes in Group 3 than in Group 1 (90% vs. 5%). In experiment 2, the rates of cleavage and development into blastocysts in Group 1 were significantly lower than those of Group 2 and 3 (8.7% and 0% vs. 50.5% and 11.6%, and 44.6% and 7.2%, respectively, P<0.05). In experiment 3, ~80% of parthenotes in Group 1 were developed with haploid chromosomal sets. However, when ionomycin was followed immediately by DMAP (Group 2). only 20% of parthenotes were haploid. In Group 3, combined treatment with ionomycin and SPP, the appearance of abnormal chromosomal tracts was significantly (P〈0.05) reduced and the proportion of haploid parthenotes was increased to 85% (17/20) than in Group 2. These results demonstrate that SPP acted as a cdc2 kinase inhibitor and formed the haploidy in oocyte activation. Thus, the present study suggests that cdc2 kinase inhibitor, such as sodium pyrophosphate, may have an effective role in oocyte activation for the production of cloned embryos/animals by nuclear transplantation.

• Ocean and Polar Research
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• v.26 no.3
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• pp.425-431
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• 2004

The study focuses on the morphology of larval and juvenile codlets, Bregmaceros atlanticus, collected from the East China Sea in May 2001 and September 2002. A total of 47 individuals were collected by using an IKMT, and the range of their body lengths was $2.41{\sim}17.18$ mm. Specimens can be categorized into two groups: larvae and juvenile. The first group, in which the yolk is completely absorbed, had a body length of 2.41m. They had big heads, and large and thick melanophores were sparsely scattered about the head, bottom of the pectoral fins, rear parts of the trunk and ends of the notochords. The specimens had a body length of 2.54mm and over, and thin and elongated body trunks. Their heads were significantly smaller, including the body depth, and melanophores were coarsely developed all over their bodies. Occipital rays, the first and unique-ray dorsal fin, were observed on individuals of body length greater than 4.01 m, and the rays grew proportionally with body length, but didn't reach the root of the second dorsal fin. The second group, juveniles, had an body length of 9.82mm and over, and their fin rays satisfied the completed numbers of rays and vertebrae for adults. Melanophores were densely scattered all over the body, where thick colors were observed on the rear parts of the dorsal and anal fins and front part of the caudal fin.

• Korean Journal Plant Pathology
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• v.14 no.6
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• pp.714-719
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• 1998

Obligate bacterial parasite attacking Heterodera glycines was firstly found from Chungju soybean field in Korea. Diameters of sporangium and central body were 5.6 ${\mu}{\textrm}{m}$ and 1.9 ${\mu}{\textrm}{m}$ under light microscopy (LM), and 3.9 ${\mu}{\textrm}{m}$ and 1.8 ${\mu}{\textrm}{m}$ under transmission electron microscopy (TEM). Endospore showed cup-shaped with smooth-type exosporium without peg-like thickening in polar area under SEM and TEM. Bacteria completed its life cycle in female of soybean cyst nematode after adhering on cuticle of second-stage juvenile. From these results, the Pasteuria found from Chungju was identified with P. nishizawae.

• Journal of Animal Science and Technology
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• v.61 no.4
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• pp.225-233
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• 2019

The aim of this study was to produce porcine tetraploid (4N) parthenogenetic embryos using various methods and evaluate their developmental potential. In method 1 (M1), porcine 4N parthenogenetic embryos were obtained by inhibiting extrusion of both first (PB1) and second (PB2) polar bodies; in methods 2 (M2) and 3 (M3), 4N parthenogenetic embryos were obtained by electrofusion of 2-cell stage diploid parthenogenetic embryos derived from inhibition of PB2 or PB1 extrusion, respectively. We found no differences in the rates of cleavage or blastocyst formation or the proportion of 4N embryos among M1, M2, and M3 groups. The different methods also did not influence apoptosis rates (number of TUNEL-positive cells/number of total cells) or expression levels of apoptosis-related BAX and BCL2L1 genes. However, total cell and EdU (5-ethynyl-2'-deoxyuridine)-positive cell numbers in 4N parthenogenetic blastocysts derived from M1 were higher (p < 0.05) than those for M2 and M3 groups. Our results suggest that, although porcine 4N parthenogenetic embryos could be produced by a variety of methods, inhibition of PB1 and PB2 extrusion (M1) is superior to electrofusion of 2-cell stage diploid parthenogenetic embryos derived from inhibition of PB2 (M2) or PB1 (M3) extrusion.

• Clinical and Experimental Reproductive Medicine
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• v.46 no.3
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• pp.119-124
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• 2019

Objective: It is widely accepted that aging decreases women's fertility capacity. The aim of this study was to assess correlations between maternal age and the morphokinetic parameters and cleavage pattern of embryos. Methods: The morphokinetics of embryos derived from women < 30, 30-35, 36-40, and > 40 years of age were compared retrospectively in terms of time of second polar body extrusion, time of pronuclei appearance, time of pronuclei fading, and time of two to eight discrete cells (t2-t8). Furthermore, abnormal cleavage patterns such as uneven blastomeres at the two-cell stage, cell fusion (Fu), and trichotomous mitoses (TM) were assessed. Results: Only t5 occurred later in women aged 36-40 and > 40 years when compared with those aged < 30 and 30-35 years (p< 0.001). Other morphokinetic timing parameters, as well the presence of uneven blastomeres, were comparable between the groups (p> 0.05). However, Fu and TM were more common in women aged > 40 years than in younger women (p< 0.001). Conclusion: Maternal age was correlated with the cleavage pattern of embryos. Therefore, evaluating embryo morphokinetics may contribute to optimal embryo selection, thereby increasing fertility in patients with advanced maternal age.

• Journal of Animal Reproduction and Biotechnology
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• v.37 no.1
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• pp.48-54
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• 2022

Parthenogenesis is maternally uniparental reproduction through the embryonic development of oocytes without fertilization. Artificial activation of mature oocytes could generate homozygous haploid embryos with the extrusion of the second polar body. However, the haploid embryos showed low embryo development in preimplantation embryos. In this study, we investigated whether the electronic fusion of the haploid embryos could enhance embryo development and ESC establishment in mice. Haploid embryos showed the developmental delay from 4-cell to the blastocyst stage. The haploid blastomeres of the 2-cell stage were fused electronically, resulting in that the fused embryos showed a significantly higher rate of blastocysts compared to non-fused haploid embryos (55% vs. 37%). Further, the embryonic stem cells (ESCs) derived from the fused embryos were confirmed to be diploid. The rate of ESC establishment in fused embryos was significantly higher compared to non-fused ones. Based on the results, we concluded that the electronic fusion of haploid embryos could be efficient to generate homozygous ESCs.

• Journal of Embryo Transfer
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• v.10 no.1
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• pp.73-82
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• 1995

large scale production of cloned embryos requires the technology of multiple generation nuclear transplantation(NT) using NT embryos as the subsequent donor nuclei. The purposes of this study were producing the second generation cloned rabbit embryos, and also to determine the electrofusion rate and in vitro developmental potential comparatively in the cloned embryos of the first and second NT generation. The embryos of 16-cell stage were collected from the mated does by flushing oviducts with Dulbecco's phosphate buffered saline(D-PBS) containing 10% fetal calf serum(FCS) at 47 hours after hCG injection In the first generation NT, the nuclear donor embryos were synchronized in the phase of Gi /S transition of 32-cell stage. The first generation NT embryos which were developed to 8-cell were synchronized in Gi /S transition phase of the following 16-cell stage and used as donor nuclei for second generation Synchronization of the cell cycle of blastomeres was induced, first, using an inhibitor of microtuble polymerization, colcemid for 10 hours to arrest blastomeres in M phase, and secondly, using a DNA synthesis inhibitor, aphidicolin for 1.5 to 2 hours to arrest them in Gi /S transition boundary. The recipient cytoplasms were obtained by removing the nucleus and the first polar body from the oocytes collected at 14 hours after hCG injection. The separated donor blastomeres were injected into the enucleated recipient oocytes by micromanipulation and were electrofused by electrical stimulation of three pulses for 60 $\mu$sec at 1.25 kV /cm in 0.28 M rnannitol solution The fused oocytes were co-cultured with a monolayer of rabbit oviductal epithelial cells in M-199 solution containing 10% FCS for 120 hours at 39$^{\circ}C$ in a 5% $CO_2$ incubator. Following in vitro culture of the first and second generation cloned embryos to blastocyst stage, they were stained with Hoechst 33342 dye for counting the number of blastomeres by fluorescence microscopy. The results obtained were summarized as follows: 1. The electrofusion rate was found to be similar as 79.4 and 91.5% in the first and second generation NT rabbit embryos, respectively. 2. The in vitro developmental potential to blastocyst stage of the second generation NT embryos (23.3%) was found significantly(p<0.05) lower, compared with that of the first generation NT embryos (56.8%). 3. The mean blastomeres counts of embryos developed to blastosyst stage following in vitro culture for 120 hours and also their daily cell cycles during the culture period were decreased significantly (p<0.05) to 104.3 cells and 1.33 cylces in the second NT generation, compoared with 210.4 cells and 1.54 cycles in the first NT generation, respectively.