Effects of cycloheximide treatment on in-vitro development of porcine parthenotes and somatic cell nuclear transfer embryos.

This study aimed to verify the beneficial effect of cycloheximide (CHX) treatment on the development of porcine somatic cell nuclear transfer (NT) embryos, which were constructed with enucleated oocytes and cumulus cells by using a single direct current (DC) pulse. In the first experiment, a single DC pulse applied to the induction of fusion and activation of NT embryos gave a high fusion rate. However, cleavage and subsequent development of fused couplets (NT embryos) to the blastocyst stage were poor. Experiment 2 was conducted to determine whether CHX treatment could enhance metaphase II (M II) oocyte activation and improve the subsequent parthenogenetic development. After giving the DC pulse and incubation with or without CHX, M II oocytes incubated with CHX showed higher cleavage and development to blastocysts compared with those incubated without CHX (P < 0. 05). Experiment 3 was carried out to verify the beneficial effect of CHX on the development of NT embryos. The NT embryos treated with the DC pulse and CHX treatment showed higher cleavage and subsequent development compared with those treated with the DC pulse alone (P < 0.05) . The present study demonstrates that CHX treatment enhances the electrical stimulus-induced activation of oocytes and NT embryos, and improves the subsequent development of parthenotes and NT embryos. The results indicate that protein synthesis inhibition treatment required for the induction of oocyte activation promotes the development of NT embryos.

Martinez Diaz MA ，Suzuki M ，Kagawa M ，Ikeda K ，Takahashi Y ... -  《JAPANESE JOURNAL OF VETERINARY RESEARCH》

Effect of activation treatments of recipient oocytes on subsequent development of bovine nuclear transfer embryos.

Atabay EC ，Katagiri S ，Nagano M ，Takahashi Y ... -  《JAPANESE JOURNAL OF VETERINARY RESEARCH》

Brief exposure to cycloheximide prior to electrical activation improves in vitro blastocyst development of porcine parthenogenetic and reconstructed embryos.

To investigate the effects of cycloheximide exposure before electrical activation of in vitro-matured porcine oocytes on the subsequent development of parthenogenetic embryos, cumulus-free mature oocytes were exposed to NCSU-23 medium containing cycloheximide (10 microg/mL) for 0, 5, 10, 20, 30 and 60 min, activated by electrical pulse treatment (1.5 kV/cm, 100 micros) and then cultured in PZM-3 for 7 days. To evaluate the effects of cycloheximide on the activation of nuclear transfer embryos, reconstructed embryos were electrically activated by two DC pulses (1.2 kV/cm, 30 micros) before or after exposure to cycloheximide. The reconstructed embryos were allocated into four groups: electrical pulse treatment alone (Ele); exposure to cycloheximide for 10 min followed by electrical activation (CHX+Ele); electrical activation followed by exposure to cycloheximide for 6h (Ele+CHX); exposure to cycloheximide for 10 min, followed by electrical activation and a further exposure to cycloheximide for 6h (CHX+Ele+CHX). The activated reconstructed embryos were cultured in PZM-3 for 6 days. Oocytes treated with 10 min exposure to cycloheximide followed by electrical activation had a significantly higher percentage of blastocyst formation compared to control oocytes and oocytes exposed for > or =30 min. In the reconstructed embryos, the blastocyst development rates of embryos exposed to cycloheximide (CHX+Ele, Ele+CHX and CHX+Ele+CHX) were significantly higher than those of the control group (Ele). Among the cycloheximide-treated groups, the CHX+Ele group had increased development rate and total blastocyst cell number, though these values were not significantly different from those observed in the other cycloheximide-treated groups. To evaluate the quality of NT embryos treated with cycloheximide, apoptosis in blastocysts was analyzed by TUNEL assay. The 10 min exposure to cycloheximide prior to electrical activation significantly reduced cell death compared with longer exposure to cycloheximide after electrical fusion. In conclusion, brief exposure to cycloheximide prior to electrical activation may increase the subsequent blastocyst development rates in porcine parthenogenetic and reconstructed embryos.

Naruse K ，Quan YS ，Kim BC ，Lee JH ，Park CS ，Jin DI ... -  《THERIOGENOLOGY》

In vitro development of preimplantation porcine nuclear transfer embryos cultured in different media and gas atmospheres.

This study investigated the effect of culture media and gas atmospheres on the development of porcine nuclear transfer embryos. Oocytes derived from a local abattoir were matured for 42-44 h and enucleated. Fetal fibroblasts were prepared from a Day 35 porcine fetus. Confluent stage fetal fibroblasts were introduced into the perivitelline space of enucleated oocytes. Fusion and activation were induced simultaneously with two direct current (1.2 kV/cm for 30 micros) in 0.3 M mannitol medium. For parthenogenetic activation, the same pulses were used. In Experiment 1, parthenogenetically activated oocytes were cultured in North Carolina State University-23 (NCSU-23), Porcine Zygote Medium-3 (PZM-3), or Beltsville Embryo Culture Medium-3 (BECM-3). Parthenogenetically activated oocytes cultured in PZM-3 had a higher (P < 0.05) developmental rate to the blastocyst stage (15.2% versus 3.7-9.6%) as compared to BECM-3 or NCSU-23. The number of nuclei in Day 6 blastocysts was higher (P < 0.05) in PZM-3 (23.6) and NCSU-23 (21.4) than BECM-3 (14.2). In Experiment 2, parthenogenetically activated oocytes were cultured in NCSU-23 under a gas atmosphere of 5% CO(2) in air for 6 days (T1), 5% CO(2), 5% O(2), 90% N(2) for 6 days (T2), 5% CO(2) in air for 3 days, then 5% CO(2), 5% O(2), 90% N(2) for 3 days (T3), or 5% CO(2), 5% O(2), 90% N(2) for 3 days, then 5% CO(2) in air for 3 days (T4). Blastocyst formation rates were not different among treatments (12.9 =/-3.6 %, 13.5 +/- 4.2%, 10.8+/-2.4%, and 12.6+/-2.7%, respectively). However, T2 (36.7+/-2.9) and T3 (33.8+/-3.0) resulted in more nuclei per blastocyst than T1 (23.2+/-2.1) or T4 (26.0+/-2.1 ). In Experiment 3, reconstructed porcine nuclear transfer (NT) embryos were cultured in NCSU-23 or PZM-3 under a gas atmosphere of 5% CO(2) in air or 5% CO(2), 5% O(2), 90% N(2). Developmental rates to blastocyst stage for porcine NT embryos cultured in NCSU-23 under a gas atmosphere of 5% CO(2) in air or 5% CO(2), 5% O(2), 90% N(2) were 7.2+/-1.4% and 12.3+/-1.4%, and the number of nuclei was 12.2=/-0.8% and 19.4+/-1.0, respectively. NT embryos cultured in PZM-3 under a gas atmosphere of 5% CO(2) in air or 5% CO(2), 5% O(2), 90% N(2) had developmental rates to blastocyst stage of 18.8+/-1.9 %, and 17.8+/-3.8% the nuclei number was 20.9 +/- 1.9 and 21.9+/-3.3, respectively. NT embryos cultured in NCSU-23 had a higher developmental rate to the blastocyst stage in 5% CO(2), 5% O(2), 90% N(2) than in 5% CO(2) in air (P < 0.05). Regardless of gas atmospheres, NT embryos cultured in PZM-3 had a higher developmental rate (18.3 =/- 1.7% versus 16.9 +/- 1.2%) and nuclei number (21.4 +/-1.8 versus 16.9 +/- 1.2) than in NCSU-23 (P < 0.05). In conclusion, a gas atmosphere of 5% CO(2), 5% O(2), 90% N(2) supported a higher development rate of porcine NT embryos than 5% CO(2) in air when the porcine NT embryos were cultured in NCSU-23. Furthermore, regardless of atmosphere, PZM-3 supported a higher development rate of porcine nuclear transfer embryos than NCSU-23.

Im GS ，Lai L ，Liu Z ，Hao Y ，Wax D ，Bonk A ，Prather RS ... -  《THERIOGENOLOGY》

Nuclear transfer of synchronized african wild cat somatic cells into enucleated domestic cat oocytes.

Gómez MC ，Jenkins JA ，Giraldo A ，Harris RF ，King A ，Dresser BL ，Pope CE ... -  《BIOLOGY OF REPRODUCTION》