• Korean Journal of Animal Reproduction
• /
• v.26 no.2
• /
• pp.95-104
• /
• 2002

This study was performed during the four seasons for the production of transgenic pigs containing the human erythropoietin(hEPO) transgene. Purebred Landrace gilts and sows approximately 8∼15 months of age (n=42) were used fur the collection of 1-cell zygotes for DNA microinjection and transfer. Retrospectively, estrus synchronization and superovulation schemes were evaluated to assess practicality for zygote collection. Synchronization and superovulation procedures were used that cyclic gilts were synchronized with 20mg altrenogest (ALT) per day for 9days after PG600 administration followed by superovulation with 1500IU pregnant mares serum gonadotropin (PMSG) and 500IU human chorionic gonadotrophin (hCG). Preparation of recombinant gene for microinjection is mice whey acidic protein promoter (mWAP) linked to human erythropoietin (hEPO) gene. After hormone treatment, 650 embryos were collected from 23 donors and 83.1% (540/650) embryos were in 1-cell stage which can be visualized the pronuclei for DNA microinjection. A total of 543 DNA microinjected embryos fiom donors were transferred to 19 synchronized recipients, seven of them maintained pregnancy and delivered 47 piglets. One of the 47 offsprings were determined to have transgene by PCR analysis. The overall rate of transgenic production was 2.13% (tansgenic/offspring). This study provides the success and useful information regarding production of transgenic pig for bioreactor research.

• Korean Journal of Animal Reproduction
• /
• v.26 no.2
• /
• pp.87-94
• /
• 2002

This study was performed during the four seasons for the production of transgenic pigs containing the Cellulase Digest Gene. Purebred Landrace gilts and sows approximately 8∼15 months of age (n=126) were used for the collection of 1-cell zygotes for DNA microinjection and transfer. Retrospectively, estrus synchronization and superovulation schemes were evaluated to assess practicality fur zygote collection. Synchronization and superovulation procedures were used that cyclic gilts were synchronized with 20mg altrenogest (ALT) per day for 9 days after PG600 administration followed by superovulation with 1000 IU pregnant mares serum gonadotropin (PMSG) and 750IU human chorionic gonadotrophin (hCG). The cellulase digestion gene for microinjection is rat elasterase promoter (rEl) linked to CelD gene. After hormone treatment, 1,422 embryos were collected from 91 donors and 95.6% (1,359/1,422) embryos were in 1-cell stage which can be visualized the pronuclei for DNA microinjection. A total of 725 DNA microinjected embryos transferred into 35 recipients and produced 65 piglets from 13 litters. Pregnancy rate according to the number of transferred embryos to recipients was higher the group which received 21 to 24 embryos (50.0%) than other groups 20.0% in less and 33.3% in more. A tail tissue was collected from 65 piglets for biopsy. PCR screening was performed on each DNA sample using two separate sets of primers specific for the 5'- and 3'-flanking region of the rEl-CelD gene. Five of the 65 piglets (7.69%) were positive for the transgene. This study provide useful information regarding production of transgenic pig for bioreactor research.

• Reproductive and Developmental Biology
• /
• v.28 no.2
• /
• pp.113-117
• /
• 2004

The present study was carried out to examine the effects of $O_2$ concentrations and culture media (North Carolina State University (NCSU)-23, porcine zygote medium(PZM)-3 or PZM-4) on in vitro development of porcine IVM/IVF embryos. Porcine oocyte-cumulus complexes were cultured in BSA-free NCSU-23 medium containing porcine follicular fluid (10%), cysteine (0.9 mM), $\beta$-mercaptoethanol (25 $\mu\textrm{g}$/$m\ell$), epidermal growth factor (10 ng/$m\ell$) and hormonal supplements (PMSG and hCG: 10 IU/$m\ell$) for 20∼22 h. They were then cultured in the same medium but without hormonal supplements for an additional 20∼22 h. After culture, cumulus-free oocyte were coincubated with liquid boar spermatozoa for 5∼6h. Putative zygotes were transferred to NCSU-23, PZM-3 and PZM-4 medium under the condition of 5% $O_2$ or 20% $O_2$ concentrations. At 48 h, no mean differences were found in cleavage rates. However, the rates of blastocyst formation at day 7 after in vitro fertilization were significantly higher in PZM-3 medium under the condition of 5% $O_2$ concentration than other treatments (19.9$\pm$2.4 vs. 11.1$\pm$2.0 to 16.0$\pm$2.5%, P<0.05). The total cell numbers of blastocysts were significantly higher in 5% $O_2$ than in 20% O2 (P<0.05). However, no differences was found among the culture media within each $O_2$ concentrations. In conclusion, the use of PZM-3 medium in 5% $O_2$ concentration was effective on in vitro development of porcine IVM/IVF embryos.

• Journal of Embryo Transfer
• /
• v.19 no.2
• /
• pp.89-99
• /
• 2004

Stretch-activated channels (SACs) responds to membrane stress with changes in open probability (Po). They play essential roles in regulation of cell volume and differentiation, vascular tone, and in hormonal secretion. SACs highly present in Xenopus oocytes and Ascidian oocytes are suggested to be involved in the regulation of pH and fluid transport to balance the osmotic pressure, but remain unclear in mammanlian oocytes. This study was investigated to find the presence of SACs in hamster oocytes and to examine their electrophysiological properties. To infer a role of SAC in relation to the development of early stage, we followed up to the stage of two-cell zygote with patch clamp techniques. Single channels were elicited by negative pressure (lower than ­15 cm$H_2O$). Interestingly, SACs were dependent on permeable cations such as $Na^+$ or $K^+$. As permeable cation removed from both sides across the membrane, SAC activity completely disappeared. When permeable cations present only in intracellular compartment, outward currents appeared at positive potentials. In contrast to this, inward currents occurred only at the negative voltage when permeable cation absent in cell interior. These result suggests that SAC carry cations through the nonselective cation channel (NSC channel). Taken together, we found that stretch activated channels present in hamster oocyte and the channel may carry cations through NSC channels. This stretch activated-NSC channels may play physiological role(s) in oocyte growth, maturation, fertilization and embryogenesis in fertilized oocytes to two-cell zygotes of hamster.

• Korean Journal of Animal Reproduction
• /
• v.20 no.2
• /
• pp.119-126
• /
• 1996

This study was carried out to determine the optimal condition for successful and efficient c cryopreservation of zygotes, 1-cell embryos, using EFS40 which was 40% (v/v) ethylene glycol diluted in DPBS medium containing 30% Fic-oll (w/v) and 0.3 M sucrose. After mouse zygote produced by IVF was vitrified by two freezing methods, the post-warming survival rates of 1-cell zygotes were assessed as cleavage to the 2-cell stage and development into the hatching blastocysts at 5 day. In the one-step method, when embryos were directly exposed to the vitrification solution at 25$^{\circ}C$ for 1 min., survival and development rates of zygotes were 85.5% and 31.9% In the two-step method, embryos were equilibrated with a dilute 20% EG for 1, 3, 5 min. before 1 min. exposure to EFS40, re-spectively. However, the rates of development (17.7, 3.3, 0%) were lower than that of one-step method. The highest survival rate (95.9%) was obtained by one-step method which exposes embryos in EFS40 for 30 sec. In this condition, 63. 8% of cleaved 2-cell developed into hatching blastocysts. In the cell number of Total and ICM using differential labelling technique, there are no significant differences in the cell number of Total and ICM between blastocysts devel oped in vitrified-thawed embryos (63.2${\pm}$16.9, 1 13.5${\pm}$4.0) and control balstocysts (54.0${\pm}$15.2, 1 12.3${\pm}$4.6). Therefore, these results show that mouse zygotes can be successfully cryopreserved by a simple vitrification method although developmental rates of vitrified embryos were reduced. In conclusion, this proposed vitrifi cation procedures can be useful in the cryopreservation of mouse IVF zygotes.

• Clinical and Experimental Reproductive Medicine
• /
• v.36 no.1
• /
• pp.55-61
• /
• 2009

Objective: To compare the clinical outcomes of ICSI with sperm retrieved from testicular tissue in patients with obstructive azoospermia (OA) or hypospermatogenesis (HS). Methods: From January 2003 through December 2006, 155 patients with OA (241 cycles) and 28 patients with HS (34 cycles) were included in this study. We compared clinical outcomes of ICSI with testicular sperm such as fertilization rate, implantation rate, clinical pregnancy rate and delivery rate. Data were statistically analyzed using t-test and ${\chi}^2$-test. Results: Testicular spermatozoa could not be retrieved in 1 out of the 21 cycles where fresh testicular sperm extraction in HS patients. Fertilization rate (FR) was significantly higher in OA than HS (75.6 % vs. 62.6%, p<0.001). Cleavage rate (CR) per fertilized zygote was also significantly higher in OA than that in HS (66.8% vs. 54.8% p<0.001). However, there were no significant differences in good embryo rate (GER), clinical pregnancy rate (CPR), implantation rate (IR) and delivery rate (DR). Conclusion: Our results show that testicular sperm of HS does not affect CPR, IR, and DR although it has shown reduced FR and CR.

• Korean Journal of Plant Tissue Culture
• /
• v.27 no.6
• /
• pp.423-428
• /
• 2000

In 1997 when cloned sheep Dolly and soon after Polly were born, it had become head-line news because in the former the nucleus that gave rise to the lamb came from cells of six-year-old adult sheep and in the latter case a foreign gene was inserted into the donor nucleus to make the cloned sheep produce human protein, factor IX, in e milk. In the last few years, once the realm of science fiction, cloned mammals especially in livestock have become almost commonplace. What the press accounts often fail to convey, however, is that behind every success lie hundreds of failures. Many of the nuclear-transferred egg cells fail to undergo normal cell divisions. Even when an embryo does successfully implant in the womb, pregnancy often ends in miscarriage. A significant fraction of the animals that are born die shortly after birth and some of those that survived have serious developmental abnormalities. Efficiency remains at less than one % out of some hundred attempts to clone an animal. These facts show that something is fundamentally wrong and enormous hurdles must be overcome before cloning becomes practical. Cloning researchers now tent to put aside their effort to create live animals in order to probe the fundamental questions on cell biology including stem cells, the questions of whether the hereditary material in the nucleus of each cell remains intact throughout development, and how transferred nucleus is reprogrammed exactly like the zygotic nucleus. Stem cells are defined as those cells which can divide to produce a daughter cell like themselves (self-renewal) as well as a daughter cell that will give rise to specific differentiated cells (cell-differentiation). Multicellular organisms are formed from a single totipotent stem cell commonly called fertilized egg or zygote. As this cell and its progeny undergo cell divisions the potency of the stem cells in each tissue and organ become gradually restricted in the order of totipotent, pluripotent, and multipotent. The differentiation potential of multipotent stem cells in each tissue has been thought to be limited to cell lineages present in the organ from which they were derived. Recent studies, however, revealed that multipotent stem cells derived from adult tissues have much wider differentiation potential than was previously thought. These cells can differentiate into developmentally unrelated cell types, such as nerve stem cell into blood cells or muscle stem cell into brain cells. Neural stem cells isolated from the adult forebrain were recently shown to be capable of repopulating the hematopoietic system and produce blood cells in irradiated condition. In plants although the term$\boxDr$ stem cell$\boxUl$is not used, some cells in the second layer of tunica at the apical meristem of shoot, some nucellar cells surrounding the embryo sac, and initial cells of adventive buds are considered to be equivalent to the totipotent stem cells of mammals. The telomere ends of linear eukaryotic chromosomes cannot be replicated because the RNA primer at the end of a completed lagging strand cannot be replaced with DNA, causing 5' end gap. A chromosome would be shortened by the length of RNA primer with every cycle of DNA replication and cell division. Essential genes located near the ends of chromosomes would inevitably be deleted by end-shortening, thereby killing the descendants of the original cells. Telomeric DNA has an unusual sequence consisting of up to 1,000 or more tandem repeat of a simple sequence. For example, chromosome of mammal including human has the repeating telomeric sequence of TTAGGG and that of higher plant is TTTAGGG. This non-genic tandem repeat prevents the death of cell despite the continued shortening of chromosome length. In contrast with the somatic cells germ line cells have the mechanism to fill-up the 5' end gap of telomere, thus maintaining the original length of chromosome. Cem line cells exhibit active enzyme telomerase which functions to maintain the stable length of telomere. Some of the cloned animals are reported prematurely getting old. It has to be ascertained whether the multipotent stem cells in the tissues of adult mammals have the original telomeres or shortened telomeres.

• Clinical and Experimental Reproductive Medicine
• /
• v.23 no.3
• /
• pp.379-384
• /
• 1996

This study was undertaken to investigate the sister chromatid exchange (SCE) frequency and embryonic development after exposure to cryoprotectants and vitrification of mouse zygotes. Mouse IVF zygotes were cryopreserved by vitrification using vitrification solution, EFS40 (40% ethylene glycol, 30% Ficoll and 0.3 M sucrose in phosphate buffer saline containing 10% FBS). After mouse zygotes were exposed to EFS40 at $25^{\circ}C$ for 30 sec., they were immediately plunged into $LN_2$ or cultured for cryoprotectant toxicity test without freezing. The results obtained in these experiments were summarized as follows: After thawing, survival rates to the 2-cell stage of zygotes exposed to or vitrified in EFS 40 (98.5%, 95.2%) were not significantly difference compared with that of control (100%). However, the developmental rates upto blastocyst and hatching blastocyst in vitrified groups (66.7, 50.0%) were lower than those of control (93.9, 81.8%) or exposed group (94.0, 78.8%) (p<0.05). When the influence of vitrification and exposure to cryoprotectant on the in vitro development of mouse zygotes was assessed by the SCE frequency, the SCE frequency in exposed ($20.2{\pm}2.1$) to or vitrified embryos ($21.4{\pm}3.2$) was higher than that in control embryos ($16.8{\pm}1.5$). These results suggest that the frequency of SCE was increased after cryoprotectant exposure or Vitrification although developmental rates of zygotes upto blastocysts and /or hatching blastocysts were not afected by cryoprotectant.