• Korean Journal of Plant Tissue Culture
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• v.24 no.4
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• pp.239-256
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• 1997

Plants belonging to the category of 2n apomixis or agamospermy form embryos and seeds without the processes of normal meiosis and syngamy. Seeds produced in this way have identical genotype of their maternal parent. Three different types of agamospermy are recognized: diplospory, apospory, and adventitious (adventive) embryony. $F_1$ hybrid cultivars cannot be used as seed sources in the next ($F_2$) generation because this generation would be extremely variable as a result of genetic segregation. Hybrid vigor is also reduced in the $F_2$ generation. Therefore, parental stocks for hybrid seed production need to be maintained and cross must be continuously repeated. Agamospermic 2n apomixis would make it possible to fix the genotype of a superior variety so that clonal seeds faithfully representing that genotype could be continuously and cheaply produced independent of pollination. That is, $F_1$ hybrid seeds could be produced for many generations without loss of vigor or genotype alteration. Production of apomictic $F_1$ hybrid seed would be simplified because line isolation would not be necessary to produce seed or to maintain parental lines, and the use of male-sterile lines could be avoided. Overall, apomixis would enable a significant reduction in hybrid seed production costs. Additionally, the production of clonal seed is not only important for seed propagated crops, but also for the propagation of heterozygous fruit trees and timbers. Clonal seed would help avoid costly and time-consuming vegetative propagating methods that are currently used to ensure the large-scale production of these plants. Apomixis is scattered throughout the plant kingdom, but few important agricultural crops possess this trait Therefore, most research to date has centered on introgressing the trait of apomixis into agricultural crops such as wheat, maize, and some forage grasses from wild distant relatives by traditional cross breeding. The classical breeding approach, however is slow and often impeded by many breeding barriers. These problems could be surmounted by taking mutagenesis or molecular approach. Arabidopsis thaliana is a tiny sexually reproducing plant and is convenient in constructing and screening in molecular researches. Male-sterile mutants of Arabidopsis are particularly suitable genetic background for mutagenesis and screening for apomictic mutants. Molecular approaches towards isolating the genes controlling the apomictic process are feasible. Direct isolation of genes conferring apomixis development would greatly facilitate the transfer of this trait to wide variety of crops. Such studies are now in progress.

• Journal of Plant Biotechnology
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• v.29 no.2
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• pp.135-138
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• 2002

Cotyledonary explants from immature zygotic embryos of each 85 recombinant inbred lines (RILs) were cultured on medium containing MS salts, B5 vitamins, 40 mg$^{-1}$ 2,4-dichlorophenoxyacetic acid and 30 g$^{-1}$ sucrose. Frequency of somatic embryo formation on cotyledonary explants showed in thirty-six lines(＜10%), in thirty-seven lines (11~49%), in nine lines (50~89%), and in three lines(>90%), respectively, The highest frequency (up to 90%) and number (6.36 per cotyledon) of somatic embryos were obtained from lines of KM1010, KM1032 and KM1064. Primary somatic embryos produced from three lines produced numerous secondary somatic embryos on the surfaces, which were subcultured for over one year. Upon transfer to maturation and conversion medium (Komatsuda, 1992), somatic embryos converted to plantlets at a frequency of approximately 25%.

• Korean Journal of Plant Tissue Culture
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• v.26 no.3
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• pp.189-195
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• 1999

This study was carried out to clarify several factors affecting embryogenesis from anther culture of nine cultivars in Brassica oleracea L. var. italica and to investigate the characteristics of plants derived from anther culture. Androgenesis from anther culture was elevated on the B5 medium supplemented with 0.1mg/L NAA, 0.1mg/L 2.4-D and 10% sucrose. Embryo production in liquid medium was five-fold higher than solid medium. High temperature treatment at 35$^{\circ}C$ for one day before transfer to culture room maintained at $25^{\circ}C$ had effective to induce embryogenesis of cultured anthers but extended treatment at 35$^{\circ}C$ decreased significantly the percent of embryogenesis. Frequency of embryogenesis from cultured anthers exhibited significant difference from 2.8% in 'Green Valiant' to 21% in 'Haisi' as affected by genotypes. Percent of spontaneously dihaploid among regenerated plants from anther culture was ranged from 62 to 74% as affected by the genotypes. Characteristic in relation to plant height, number of leaves and branches, and size of head from anther-derived plants showed differential variation in 'Rokguray' and 'Haisi'. Among these charaters obtained from two cultivars, five lines were selected for early maturity, long plant height and large head. Selected lines were used as breeding meterials for F$_1$ hybrid.

• Korean Journal of Animal Reproduction
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• v.21 no.1
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• pp.47-52
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• 1997

The objective of this study was to investigate the in vitro / in vivo embryonic development after vitrification of mouse zygotes and the chrom osomal normality of delivered live young after embryo transfer. Mouse IVF zygotes were cryopreserved by vitrification using vitrification solution, EFS40 (40% ethylene glyc이, 30% Ficoll a and 0.3 M sucrose in phosphate buffer saline c containing 10% FBS ) . After mouse zygotes were exposed to EFS40 at 25"C for 30 sec., they were immediately plunged into LN$_2$. Vitrified thawed mouse zygotes were cultured upto bIastocysts in M16 for 4 days. The rates of in vitro development were 71.5% under this condition. Cultured blastocysts were transferred to recipients (3 day of pseudopregnant) on one or both uterus horns (6-8 embryos per a uterus horn). And all recipients were allowed to produce litters. The results obtained in these experiments were summarized as follows: The pregnancy rates and in vivo survival rates, live fetus rates, for vitrified zygotes (80.0, 39.6%) were not significantly difference in those of control zygotes (77.8%, 50.0%). Also, all of live-born young mice were chromosomally normal (n=40). This results suggested that proposed rapid vitrification procedures can be effectively use in 1-cell mouse zygotes cryopreservation.

• Clinical and Experimental Reproductive Medicine
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• v.15 no.2
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• pp.135-147
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• 1988

To compare the stimulation effect of the ratio in follicle stimulating hormone and luteinizing hormone in induction of multiple follicular growth, the serum $E_2$ level, the diameter of follicle, number of aspirated follicles and cleavage rate of in vitro fertilized preovulatory oocytes as well as the pregnancy rate were evaluated. Forty one patients with irreparable tubal disease were stimulated by hMG(n=24) or FSH/hMG(n=17) for the purpose of in vitro fertilization and embryo transfer. The following results were obtained. 1. Serum estradiol($E_2$) levels on the day of hCG administration were $921.0{\pm}353.3\;pg/ml$ in hMG group and $1272.9{\pm}1060.6\;pg/ml$ in FSH/hMG group. The serum $E_2$ value of hMG group was significantly lower than that of FSH/hMG group. 2. The diameter of leading follicle by ultrasonogram on the day of hCG administration were $16.2{\pm}2.0\;mm$ in hMG group and $16.2{\pm}2.6\;mm$ in FSH/hMG group. No significant difference of follicle diameter between two groups was demonstrated. 3. The number of follicles with diameter above 10 mm by sonogram on the day of hCG injection were $3.91{\pm}2.32$ in hMG group and $6.52{\pm}3.86$ in FSH/hMG group. There was significant difference of number of follicles between two groups, (p< 0.01). 4. The number of oocytes found per patient at aspiration were $2.59{\pm}1.00$ in hMG group and 3. $76{\pm}2.31$ in FSH/hMG group. There was significant difference of number of aspirated oocytes between two groups. (p< 0.05). 5. The detection rate of preovulatory oocyte at aspiration were 68.4%(39/57) in hMG group (n=22) and 77.6%(38/49) in FSH/hMG group (n=13). 6. The cleavage rate of preovulatory oocyte at 44 hours after insemination were 74.4%(29/39) in hMG group(n=22) and 81.6%(31/38) in FSH/hMG group (n=13). When only hMG was used, one pregnancy was established in 15 patients to whom 29 zygotes were transferred. And a full term normal female baby was delivered by elective cesarean section. In the FSH/hMG group, five pregnancies out of 9 transferred patients were confirmed by serum ${\beta}-hCG$. Two pregnancies were spontaneously aborted before the 6th week of pregnancy. One patient aborted her baby at the 18th week of pregnancy because of incompetent internal os of the cervix. Two patients delivered two full term babies by elective cesarean section. From the above findings, paralell with the increase in the ratio of exogenous follicle stimulating hormone to luteinizing hormone, an increase in oocyte recovery was observed as well as an improvements in pregnancy rate. It was concluded that FSH enrichment early in the follicular phase had a beneficial effect in the controlled ovarian hyperstimulation.

• Clinical and Experimental Reproductive Medicine
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• v.31 no.3
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• pp.169-176
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• 2004

Objective: This study was performed to evaluate and compare the embryonic developmental capacity and pregnancy rates in conventional in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) with ejaculated sperm or testicular sperm cycles. Materials and Methods: Fertilization was examined in the following morning after IVF (group I), ICSI (group II) or TESE-ICSI cycles (group III). Fertilized oocytes were co-cultured with Vero cells until embryo transfer (ET). On day 2 and $5{\sim}7$, grades of embryos (<4- or $\geq$4-cell) and blastocysts (BG1, 2, 3 or early) were evaluated. Clinical pregnancy rate was determined by detecting G-sac with transvaginal ultrasonogram. We analyzed the results by $X^2$ and Student's t-test and considered statistically significant when P value was less than 0.05. Results: Fertilization rate was significantly higher (p<0.05) in group I ($79.0{\pm}21.2%$) than in group II and III ($56.8{\pm}21.6%$ and $36.7{\pm}25.3%$). Cleavage and blastulation rate of group I ($95.8{\pm}13.8%$ and $59.5{\pm}25.3%$) were significantly higher (p<0.05) than those of group III ($83.4{\pm}18.6%$ and $40.4{\pm}36.5%$). Clinical pregnancy rate was significantly higher (p<0.05) in group I and II (40.7% and 41.7%) than that in group III (12.5%). No differences were found in the rates of multiple pregnancy and abortion among three groups. Embryonic implantation rate was higher in group I ($15.1{\pm}20.2%$, p<0.05) and II ($14.7{\pm}20.6%$, NS) than that in group III ($5.1{\pm}15.6%$). However, embryonic implantation rate was increased in ET with blastocyst(s) among three groups. Conclusions: Fertilized oocytes obtained from TESE-ICSI were harder to be successfully cultured to blastocyst stage for 5$\sim$7 days than that from IVF cycles. However, all blastocyst(s) ET increased the embryonic implantation rate equally in IVF, ICSI and TESE-ICSI cycles.

• Journal of Plant Biotechnology
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• v.29 no.3
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• pp.189-192
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• 2002

An efficient plant regeneration system of major cultivars of sweetpotato (Ipomoea batatas (L.) Lam.) in Korea via somatic embryogenesis was established. Embryogenic calli were formed from shoot apical meristems of sweetpotato cultivars when cultured on LS medium supplemented with 1 mg/L auxin (2,4-D, picloram, dicamba). Among three kinds of auxin, 1 mg/L 2,4-D showed the highest embryogenic calli induction rate. After 4 weeks of cultures on LS medium supplemented with 1 mg/L 2,4-D, embryogenic calli induction rates of Sinhwangmi, Zami, Yulmi, and White Star were 86%, 78%, 76%, and 80%, respectively. Upon transfer onto LS basal medium, most of somatic embryos developed into plantlets. Regenerated plantlets were transplanted to potting soil and grown to mature plants in a greenhouse.

• Clinical and Experimental Reproductive Medicine
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• v.45 no.3
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• pp.135-142
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• 2018

Objective: To prospectively evaluate the efficacy and safety of a fixed early gonadotropin-releasing hormone (GnRH) antagonist protocol compared to a conventional midfollicular GnRH antagonist protocol and a long GnRH agonist protocol for in vitro fertilization (IVF) in patients with polycystic ovary syndrome (PCOS). Methods: Randomized patients in all three groups (early antagonist, n = 14; conventional antagonist, n = 11; long agonist, n = 11) received 21 days of oral contraceptive pill treatment prior to stimulation. The GnRH antagonist was initiated on the 1st day of stimulation in the early antagonist group and on the 6th day in the conventional antagonist group. The GnRH agonist was initiated on the 18th day of the preceding cycle. The primary endpoint was the number of oocytes retrieved, and the secondary endpoints included the rate of moderate-to-severe ovarian hyperstimulation syndrome (OHSS) and the clinical pregnancy rate. Results: The median total number of oocytes was similar among the three groups (early, 16; conventional, 12; agonist, 19; p= 0.111). The early GnRH antagonist protocol showed statistically non-significant associations with a higher clinical pregnancy rate (early, 50.0%; conventional, 11.1%; agonist, 22.2%; p= 0.180) and lower incidence of moderate-to-severe OHSS (early, 7.7%; conventional, 18.2%; agonist, 27.3%; p= 0.463), especially among subjects at high risk for OHSS (early, 12.5%; conventional, 40.0%; agonist, 50.0%; p= 0.324). Conclusion: In PCOS patients undergoing IVF, early administration of a GnRH antagonist may possibly lead to benefits due to a reduced incidence of moderate-to-severe OHSS in high-risk subjects with a better clinical pregnancy rate per embryo transfer. Further studies with more subjects are required.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.224-230
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• 2019

The purpose of the study is to investigate the change in the blood progesterone (P4) and estrogen (E2) levels when applying different estrus induction protocols to Korean black goats, and this was done to gain understanding about their reproduction physiology. For the experiment, we performed three estrus induction protocols that are commonly used in bovine: controlled internal drug release (CIDR) + prostaglandin $F2{\alpha}$ ($PGF2{\alpha}$), $PGF2{\alpha}$ + gonadotropin-releasing hormone (GnRH) + $PGF2{\alpha}$, and CIDR + $PGF2{\alpha}$ + PMSG. The P4 and E2 concentrations showed different patterns until the last treatment of the three protocols. However, similar concentration patterns were shown after the last treatment in all the protocols. In conclusion, we monitored the blood P4 and E2 levels in Korean black goats following three different estrus induction protocols. Our findings may be used in other breeding programs of Korean black goats, such as artificial insemination and embryo transfer.

• Korean Journal of Animal Reproduction
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• v.9 no.2
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• pp.140-147
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• 1985

Seventy four Holstein heifers were randomly assigned over three trials to PRID-7+PG-6 and Synchromate B-9 regimens to synchronize estrus cycle for embryo transfer. Sexual behaviors; moounting, standing, orientation, chin-resting, sniffing, licking, rubbing and butting, vaginal swelling and mucus discharge were observed between 06-08, 12-14 and 18-20 h on 1st day and 00-02, 06-08, 12-14 and 18-20 h on 2nd day after removal of hormones. Synchromate-B treatment (81.6%) showed higher synchronized estrus rate than PRID treatment (77.8%) during observation period. Standing estrus was observed within 74 h after PG injection in PRID and within 52 h after removal of implant in Synchromate-B. About 68% of heifers in PRID and 74% of heifers in Synchromate-B showed standing estrus between 0-14 h on 2nd day after removal of the hormones. Synchromate-B resulted in a tighter synchrony of standing estrus than PRID. Incidence of average mounting and standing per head during observation period was 22.3 and 16.6 in PRID and 28.1 and 13.6 in Synchromate-B. The PRID showed peak in active mounting at 18-20 h on 1st day, however, the Synchromate-B showed at 0-2 h on 2nd day after removal of hormone. Active standing was shown between 18 h on 1st day to 20h on 2nd day in PRID, however, between 0-14 h on 2nd day after removal of hormone is Synchromate-B. There was slight difference in pattern of active mounting and standing during estrus between PRID and Synchromate-B. Conception rate of synchronized heifers transferred with fresh and frozen embryos by non-surgical and surgical methods was higher in synchromate-B (62.5%) than in PRID (38.5%). Chin-resting showed highest incidence among 6 sexual behavioral components in the both treatments. Synchromate-B showed higher incidence of chin-resting (16.6) than PRID (10.7). Synchromate-B group showed also higher incidence of orientation, sniffing and butting than PRID group. Synchromate-B resulted in more active sexual behaviors than PRID. The pattern of incidence of chin-resting, licking and butting was almost symmetrical in PRID with their peak values at 6-8 h on 2nd day, however in Synchromate-B chin-resting and sniffing was symmetrical with their peak values at 12-14 h on 2nd day after removal of hormone. There was tendency to increase vaginal swelling according to time passage of synchronized estrus in the both treatments. Incidence of mucus discharge in Synchromate-B was slightly higher than in PRID. Twenty to 40% was false negative in conception rate by tall painting before re-estrus day as judged by rectal palpation.