• Korean Journal of Animal Reproduction
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• v.23 no.1
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• pp.13-18
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• 1999

The totipotential spermatogonial stem cells of adult testis which give rise to mature sperm cells is well-known to incorporate foreign DNA as well as those of somatic cells. Also, the integration rates of foreign DNA after haploid stages are generally known to decrease and /or is simply bound foreign DNA into the sperm plasma membrane. To overcome these problems, liposome and DNA complexes were used to determine how direct injection of these complexes into testis were integrated into sperm genome and resulted in transgenic offspring. To study this purpose, cation liposome was gently mixed with WAF/hGH DNA (1 : 2) and the complexes were injected into testis. At 10, 20, 40, 60, and 80 days after direct injection into testis, mature sperm cells were recovered by using artificial virgin method from two goats and each semen except a part of semen used for DNA analysis such as PCR or Southern blotting was cryopreserved for the artificial insemination. The results obtained in this study are summarized as follows. 1. By PCR, the presence of exogenous DNA was confirmed up to 80 days after injection with liposome/DNA complexes. The highest integration rates were obtained at day 40 after direct injection. This results suggested that spermatogonial stem cells were integrated exogenous DNA into their genome. 2. Among 23 Korean Native Goats which were artificially inseminated, 4 goats resulted in pregnancy and produced 7 young goats. 3. Two young goats were confirmed as a transgenic by PCR and Southern blot analysis. Therefore, our results suggested that testis-mediated gene transfer can be used as a feasible tools for the production of transgenic livestock.

• Korean Journal of Animal Reproduction
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• v.24 no.1
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• pp.59-67
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• 2000

This study was investigated the developmental potential of bovine embryos following nuclear transfer with bovine fetal fibroblasts (BFF). BFF were isolated from a male 45-day-old-fetus. Non-starved BFF labeled with MitoTracker were transferred into perivitelline space of enucleated oocytes. BFF-oocyte units were fused by electric pulse, and then fused oocytes were activated with calcium ionophore A23187 and subsequently 6-dimethylaminopurine (6-DMAP). The resulting zygotes were placed into CRlaa bovine embryo culture medium. Transfer of the nucleus into enucleated oocyte led to premature chromosome condensation, swelling and pronucleus formation. Remodeled oocytes were developed to the mitotic and 2-cell stage at 18 to 26 h after nuclear transfer. The incidence of in vitro development to the blastocyst stages was 21% of fused oocytes. Mitochondria of BFF eliminated rapidly and were not detected at 8 h after fusion. These results suggest that BFF can be successfully reprogrammed in enucleated bovine oocytes, and that reconstructed embryos can develop to the blastocyst stage.

• Korean Journal of Animal Reproduction
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• v.27 no.2
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• pp.143-152
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• 2003

The objective of this study were to investigate the effects of Se and Vit. E administration on blood chemical values and Vit. E concentrations of serum in calves born from Hanwoo dams injected Se and Vit. E at late pregnancying periods. The effects of Se and Vit. E administration of blood chemical values in calves born from Hanwoo dams injected Se and Vit. E at the last month of pregnancying periods were examined. In albumin concentration of blood, the Vit. E 2000IU group were slightly higher than other groups and the cholesterol concentrations were also higher in Vit. E 15001u group than other groups. But, another components examined of blood chemical values were not significantly different in all experimental groups. The blood chemical values in calves born from Hanwoo dams administrated Se and Vit. E at two months before parturition were examined. However, there were not significantly different in all experimental groups in concentrations of albumin, cholesterol, BUN, creatinine, glucose, inorganic phosphorous, calcium, total protein and triglycerides. The concentrations of serum Vit. E in calves born from Hanwoo dams administrated Se and Vit. E at 30 and 15 days before parturition were examined. The concentrations of Vit. E in serum were higher in treatment groups than in control group(P>0.05). The concentrations of serum Vit. E in calves born from Hanwoo dams administrated Se and Vit. E at 60 days before parturition were examined, the concentrations of Vit. E in serum were slightly higher in groups administrated than in control group(P>0.05), but there were not significantly difference in all experimental groups.

• Korean Journal of Animal Reproduction
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• v.26 no.2
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• pp.133-142
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• 2002

The objective of this study was to examine maturation, fertilization and developmental rate of the in vitro-grown mouse oocytes, and to compare these results with those of oocytes grown and matured in vivo. The preantral follicles isolated from 12-day-old mice were cultured on Transwell-COL membrane inserts. After in vitro growth and maturation, 72.5 % of oocytes grown in vitro produced polar body which can be comparable to in vivo growth (70.5 %). However, the mean oocyte diameter of the in vitro group (69.6$\pm$2.1$\mu$m) was smaller than that of the in vivo group (73.3$\pm$3.0$\mu$m). The fertilization rate was significantly lower (p<0.05) in the in vitro group (76.5%) than in the in vivo group (90.2%), however, there was no difference in the percentage of monospermic and polyspermic oocytes between two groups. The capacities of in vitro grown ova to cleave and develop to blastocyst were (57.8 and 14.4%, respectively) significantly lower (p<0.001) than those of the in vivo counterpart (84.4 and 56.6%, respectively). Moreover, the mean number of cells per blastocyst was significantly lower (p<0.05) in the in vitro group (39.0$\pm$10.8) than in the in vivo group (60.5$\pm$12.5). Live young were produced from transferred 2-cell embryos derived from in vitro-grown and matured oocytes. In conclusion, the results show that in vitro-grown oocytes did not achieve the developmental capacity of in vitro-grown oocytes.

• Korean Journal of Animal Reproduction
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• v.26 no.2
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• pp.173-182
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• 2002

The mechanisms underlying of the visual assessment and resulting in optimum embryonic development following in vitro maturation, fertilization, and culture are unclear, It was known that in vitro produced embryos show more frequent occurrence of fragmentation, which resulted in poor developmental potential and decreased implantation rate. The objective of this study was to investigate the apoptotic rates in bovine blastocyst derived from in vitro fertilization (IVF) and nuclear transfer (NT). In addition, the expression levels of Bcl-2 and Bax gene were investigated in the blastocyst to confirm their potential roles in the regulation of apoptosis during preimplantation embryonic development. Analysis of apoptosis was carried out by using terminal deoxynucleotidyl transferase mediate dUTP nick end labeling (TUNEL) method. The levels of Bcl-2 and Bax gene in the blastocyst derived from IVF and NT were determined by RT-PCR. The proportion of TUNEL positive signal in blastocyst derived from NT was significantly higher than that in blastocyst derived from IVF (p<0.001). Bcl-2 expression level of blastocyst derived from IVF was higher than that of blstocyst derived from NT. However, high expression level of Bax was observed in the blastocyst derived from NT. These results indicates that apoptosis is more responsible for fiagmentation in bovine blastocyst derived from NT than IVF. These results suggested that the increase of developmental failure followed by NT could be caused by nuclear fragmentation as apoptosis.

• Korean Journal of Animal Reproduction
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• v.25 no.4
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• pp.305-315
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• 2001

In this study, the production of transgenic embryo was attempted by microinjection or round spermatid cultured with foreign DNA. At first, the expression of haploid spermatids specific gene, mTP1 in mouse and hPrm2 in hamster spermatids were investigated by RT-PCR method in testes of young mice and hamster testis. The specific gene expression first appeared at 18 days post partum (dpp) in mice spermatid and 20 dpp in hamster spermatid. Therefore, the round spermatids isolated from 17 dpp mice and 19 dpp hamster were used for the introduction of foreign EGFP gene into haploid round spermatids. For the introduction of EGFP gene haploid round spermatids suspended in medium including EGFP gene were treated with a different electric field strength at 0.11, 0.18 and 0.44 ㎸/cm. After electrical stimulation, viability of testicular sperm cells and 67.6%, 66.4% and 49.9%, in mice and 62.6%, 57.9% and 27% in hamster, respectively. These values were significantly lower than those of non-treated control groups 80.5% in mouse and 69.1% in hamster After 72 hrs culture, the highest expression rate of EGFP gene, 28.5% in mice and 32.1% in hamster were obtained from tile spermatogenic cells electroporated by the field strength or 0.18 ㎸/cm. Then, the ability of fertilization and embryonic development of haploid spermatids transfected with foreign EGFP gene were estimated by the microinjection of spermatids into hamster oocytes. The Irate pronuclear formation rate (77.5%) was lower than non-treated control (80%), and the cleavage rate of the treated group (58.8%) was lower than control (65%). To prove the foreign EGFP integration in hamster embryos, 2-cell stage hamster embryos were subjected to the observation under the fluorescence microscope, and the PCR analysis. As a result, about 44% of 2-cell embryos were showed the integration of EFGP gene into their genome. Therefore, These results suggest the possibility to produce transgenic hamsters by microinjection of haploid spermatid transfected with foreign DNA.

• Journal of Animal Science and Technology
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• v.55 no.5
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• pp.343-349
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• 2013

Data including 1,372,050 milk records pertaining to 438,019 cows from 1983 to 2011 collected during performance tests conducted by the National Livestock Cooperative Dairy Improvement Center were used to calculate milk income and profit of individuals and investigate the effects of production levels of early lactation (parity 1 and 2, respectively). Individuals with a moderate level of early lactation stayed longer in herds. Among parity 1, the 9,000 kg or higher group had a lower mean number of lactations than the overall mean of 3.13. The 7,000 kg or lower and 10,000 kg or higher groups had lower mean life time milking days than the overall mean of 1,076.8 days. Standard deviations of lifetime traits tended to decrease as production levels increased. For parity 2, the 11,000 kg or higher group had a lower mean number of lactation than the overall mean of 3.43. The lifetime milking days was highest in the 12,000 kg group (1,212.0 days), and generally smaller in the lower groups. Profit increased as the production level of groups increased for both parity 1 and 2. In groups with low production levels, profit of parity 1 was higher than that of parity 2, while the reverse was true in groups with high production levels. These results suggest that individuals in the low production groups had a greater likelihood to be culled due to reproductive or other problems. Furthermore, the accuracy of the prediction of lifetime profit of individuals with a milk yield of 305 days seems to be higher for parity 2 than parity 1; therefore, it is desirable to predict lifetime profit using the 305d milk yield of parity 2. In conclusion, breeding goals are based on many factors in functions for the estimation of profit; however, production levels during early lactation (parity 1 and 2) can be used as indicators of profit to extend profitability.

• Korean Journal of Animal Reproduction
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• v.24 no.4
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• pp.395-406
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• 2000

The present study was conducted to examine the developmental capacity of mouse oocytes within prenatal follicles cultured various concentrations of FSH and LH and the expression of cytochrome P450 cholesterol side-chain cleavage enzyme (P450scc) and cytochrome P450 17 $\alpha$ -hydroxylase (P450)$_{17{\alpha}}$ mRNA, as luteinization and atretic marker, in these culture conditions. In addition, we investigated the concentrations of progesterone and testosterone in culture medium. The developmental potential up to blastocyst of the oocytes grown in vitro was higher in the FSH alone (30.2%) and 10 $m\ell$U/$m\ell$ LH and 100 $m\ell$U/$m\ell$ FSH treated (28.0%) groups than in the 100 $m\ell$U/$m\ell$ LH and 100 $m\ell$U/$m\ell$ FSH treated group (22.0%). And the mean numbers of cell per blastocyst was higher in the FSH alone (50.9$\pm$26.1) and 10 $m\ell$U/$m\ell$ LH and 100 $m\ell$U/$m\ell$ FSH treated (51.0$\pm$21.1) groups when compared to the 100 $m\ell$U/$m\ell$ LH and 100 $m\ell$U/$m\ell$ FSH treated group (45.2$\pm$15.1). The expressions of P450scc and P450$_{17{\alpha}}$ mRNA in the oocyte -cumulus complexes were increased with increasing of LH concentration, and also the secretions of progesterone and testosterone were increased. Especially, in the 100 $m\ell$U/$m\ell$ LH and 100 $m\ell$U/$m\ell$ FSH treated group, the expression of P450scc and P450$_{17{\alpha}}$ were significantly increased, and the secretion of progesterone and testosterone were significantly increased. Therefore, these data show that gonadotrophins are essential for the in vitro culture of preantral follicles, but that increasing of LH concentration is reduced the developmental capacity of oocytes. The cause of these findings may be due to increasing of progesterone and testosterone secretion by the enhance of P450scc and P450$_{17{\alpha}}$ mRNA expressions, as markers of luteinization and atresia. Conclusively, this study suggest that supplementation of 100 $m\ell$U/$m\ell$ FSH or 10 $m\ell$U/$m\ell$ LH and 100 $m\ell$U/$m\ell$ FSH may be optimal condition for the culture of mouse pre antral follicles.

• Korean Journal of Environment and Ecology
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• v.26 no.3
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• pp.333-341
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• 2012

To investigate the feeding habits of the Kaloula borealis, the stomach contents of 52 out of 56 specimens collected around Daejung-up, Jeju Island in June 2011 were studied. The stomach contents were analyzed with the stomach flushing method. According to the results, the main preys of the Kaloula borealis were Diptera sp., Harpalidae, Formicidae and Drosophilidae. the Kaloula borealis of all sizes fed on small preys, while individuals with large SVL fed on big preys. By feeding on a large amount of food with a small number of activities, the individuals with large SVL is considered to enhance energy efficiency. In many cases, the Kaloula borealis fed on Diptera sp. or Drosophilidae, which are slow but active and capable of flying. As a result, the Kaloula borealis take the sit-and-wait form of preying rather than actively searching for food. The results of this research on feeding habits of the Kaloula borealis will provide valuable resources to protect the endangered Kaloula borealis experiencing a sharp decline in their population and to prepare plans for population preservation strategies for them.

• Reproductive and Developmental Biology
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• v.35 no.1
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• pp.85-91
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• 2011

The objective of this study was to evaluated the efficiency on sperm cryosurvival and ability of in vitro fertilization using Triladyl and Lactose Egg-Yolk(LEY) as extenders for cryopreservation of separated sperm by 65% percoll in miniature pig. Sperm viability was measured with SYBR-14/PI double stained sperm by flow cytometry. Ability on embryo cleavage rate and blastocyst development were observed by in vitro fertilization after frozen-thawing of sperm separated by 65% percoll. The experimental groups were designed that separated sperm by 65% percoll with Triladyl (ST) or LEY(SL) and unseparated sperm with Triladyl(UT) or LEY(UL) for cryopreservation. As a results, the viability was significantly(p<0.05) higher in ST(55.1%), SL(63.1%), UL(58.8%) than UT(38.2%) group. Sperm viability in SL(63.1%) group was significantly(p<0.05) higher than other experimental groups. On the other hand, embryo cleavage rate was significantly(p<0.05) higher in ST(79.1%), SL(83.2) than UT(74.1) and UL(75.7%) groups at 96h after in vitro fertilization. Blastocyst development was also significantly(p<0.05) higher in ST(21.5%), SL(20.9%) than UT(17.0%) and UL(18.8%) groups. In conclusion, cryopreservation of miniature boar sperm separated by 65% percoll were beneficial to viability and capacity on in vitro fertilization.