scholarly journals 68 EFFECT OF XENOPUS EGG EXTRACT TREATMENT OF DONOR CELLS ON PORCINE SOMATIC CELL NUCLEAR TRANSFER

2010 ◽  
Vol 22 (1) ◽  
pp. 192
Author(s):  
Y. Liu ◽  
O. Østrup ◽  
J. Li ◽  
G. Vajta ◽  
L. Lin ◽  
...  

Pretreatment of somatic cells to promote subsequent reprogramming during somatic cell nuclear transfer (SCNT) may significantly improve efficiency of the technique. The aim of this study was to evaluate the effect of Xenopus laevis egg extract pretreatment of porcine fetal fibroblast cells using different permeabilization agents prior to SCNT. Fibroblasts were permeabilized using streptolysin O (SLO; 300 ng mL-1, 30 min, 37°C) or digitonin (7 μg mL-1, 2 min, 4°C), and exposed to egg extract for 1 h or 0.5 h, respectively. Cell membranes were resealed in DMEM supplemented with 2 mM CaCl2 for 2 h. After culture for 1, 3, and 5 days (for SLO) or 3 and 5 days (for digitonin), the SLO extract-treated cells (SETC) and digitonin extract-treated cells (DETC) were used as donor karyoplasts for handmade cloning. Controls were SCNT with nontreated cells. Embryos were evaluated for cleavage rate (Day 2), blastocyst rate (Day 6), and total cell numbers of blastocysts. Statistical differences were analyzed by ANOVA. Results are summarized in Table 1. When SETC were used as donors, blastocyst rates were significantly lower compared with the controls, except when the donor cells were cultured for 3 days after treatment. Blastocysts of the latter group also had higher total cell number. With DETC as donors, blastocyst rates and total cell number of embryos at Day 6 reconstructed with cells cultured for 5 days were higher than those in other groups. Results indicate that extract treatment of the donor cells after SLO-permeabilization can give higher number of cells in cloned blastocysts but not improve overall embryo development. However, digitonin treatment for donor cell permeabilization improved both embryo development and cell number of blastocyst. The latter effect was detected only 5 days after the treatment. In conclusion, qualitative efficiency of porcine SCNT could be improved with a combined donor cell permeabilization and extract treatment. Table 1.Effect of different permeabilization agents prior to SCNT

2008 ◽  
Vol 20 (1) ◽  
pp. 99 ◽  
Author(s):  
A. E. Iager ◽  
Z. Beyhan ◽  
P. J. Ross ◽  
N. P. Ragina ◽  
K. Cunniff ◽  
...  

Faulty epigenetic reprogramming is a likely major cause of the low success rate observed in all mammals produced through somatic cell nuclear transfer (SCNT). It has been reported that treatment of reconstructed mouse embryos with the potent histone deacetylase inhibitor, trichostatin A (TSA), results in significantly increased developmental capacity of SCNT preimplantation embryos and live offspring (Kishigami et al. 2006 Biochem. Biophys. Res. Commun. 240, 183–189; Rybouchkin et al. 2006 Biol. Reprod. 74, 1083–1089; Kishigami et al. 2006 J. Reprod. Dev. 53, 165–170). Studies investigating similar reprogramming capabilities of TSA in bovine SCNT embryos report conflicting results (Akagi et al. 2007 Reprod. Fertil. Dev. 19, 24 abst; Iwamoto et al. 2007 Reprod. Fertil. Dev. 19, 48 abst). In this study, the effects of TSA treatment on in vitro development of bovine SCNT embryos were examined. Bovine fetal fibroblasts were cultured under contact inhibition for 2 to 5 days and used as donor cells for SCNT. Oocytes were aspirated from abattoir-derived ovaries, and matured in vitro for 18 h prior to enucleation. Reconstructed SCNT couplets were electrofused, and then activated 24 h post-maturation using 5 µm ionomycin followed by 2 mm dimethylaminopurine (DMAP) for 4 h. SCNT embryos were subjected to 0 (control; C-NT) or 50 nm TSA for 13 h post-ionomycin (hpi) TSAa-NT) or 13 hpi + 6 h starting from 40 hpi (TSAb-NT). IVF embryos were produced as an additional control. All embryos were cultured in KSOM supplemented with 3 mg mL–1 BSA for 7.5 days, with 5% FBS added on Day 3. Experiments were repeated 3 or 7 times, and data were analyzed a -way ANOVA procedure. Developmental rates to the blastocyst stage and total cell number of blastocysts were determined. Total cell numbers were determined by fixing blastocysts in 4% paraformaldehyde, and staining with bisbenzimide 33342, followed by microslide mounting and visualization using an epifluorescence microscope. No difference was observed in cleavage rates among the four treatment groups, C-NT, TSAa-NT, TSAb-NT, and IVF, with the rates being 66%, 75%, 73.1%, and 82.3%, respectively (P = 0.33); nor was any improvement seen in the rate of blastocyst development of TSAa-NT or TSAb-NT over C-NT embryos: 36%, 40.2%, and 30.2%, respectively (P = 0.22). Furthermore, there was no significant difference in mean total cell number of blastocysts among treatment groups: C-NT, 120.2; TSAa-NT, 124.2; TSAb-NT, 129.3; and IVF, 141.1 (P = 0.29). These results suggest that 50 nm TSA treatment immediately following activation does not affect the development of bovine SCNT preimplantation embryos.


2009 ◽  
Vol 21 (1) ◽  
pp. 123
Author(s):  
H. J. Oh ◽  
J. E. Park ◽  
M. J. Kim ◽  
S. G. Hong ◽  
J. T. Kang ◽  
...  

Epigenetic reprogramming such as acetylation in somatic cell nuclear transfer (SCNT) has been known as one of problems in cloned embryos. For resolving this acetylation reprogramming, many investigators recently have reported the effect of long-term culture of post-activated SCNT embryos using trichostatin A (TSA), a histone deacetylase inhibitor (HDACi). The objective of this study is to investigate the effect of short-term TSA treatment on in vitro developmental ability and the quality of bovine SCNT embryos. Immature oocytes were aspirated from abattoir-derived ovaries, matured in vitro for 22 h, and enucleated. A bovine fetal fibroblast was placed into the enucleated oocyte and fused by electrical stimulation. The fused couplets were activated by 4-min incubation in 10 μm ionomycin, followed by 4 h of culture in 1.9 mm 6-dimethylaminopurine with or without TSA (0, 50, or 100 nm). The SCNT embryos were subsequently cultured in modified synthetic oviduct fluid medium for 8 days. Developmental competence was assessed by blastocyst formation and total cell number. Total cell numbers were determined by staining with bisbenzimide 33342. As results, developmental competence to blastocysts was higher in 100 nm than control (36.7 v. 27.9%, P < 0.05). In blastocyst hatching rate, TSA 100 nm group (19.5%) at 8 days showed an increased pattern as opposed to control and TSA 50 nm group (11.1 and 12.7%; P < 0.05). No significant differences in two cell and morula stage were observed among treatment groups. In terms of development to hatching stage of blastocysts, TSA 100 nm group (19.5%) at 8 days has a significant effect compared to control and TSA 50 nm group (11.1 and 12.7%; P < 0.05). Total cell number of blastocysts derived from TSA 100 nm was significantly higher (P < 0.05) than that in TSA 50 nm (116 v. 100), whereas there was not significant difference between control and TSA 100 nm. In conclusion, short-term culture with high concentration of TSA improved the blastocysts formation however total cell number of blastocysts showed contradictory result. The epigenetic modification by TSA treatment on bovine SCNT needs further investigation. This study was financially supported by KOSEF (grant # M10625030005-08N250300510) and the Korean MEST, through the BK21 program for Veterinary Science.


2009 ◽  
Vol 21 (1) ◽  
pp. 178 ◽  
Author(s):  
B. M. Kumar ◽  
E. St. John ◽  
P. M. Mackie ◽  
W. A. King ◽  
G. F. Mastromonaco

Wood bison (Bison bison athabascae) are currently classified as threatened in Canada. Interspecies somatic cell nuclear transfer (iSCNT) is a valuable tool for embryo production in non-domestic species in which access to gametes is limited. Unlike fertilization, SCNT allows preservation of the entire genome, thus avoiding dilution of valuable alleles, an important factor for the preservation of genetic diversity. The present study compared the developmental competence of iSCNT embryos reconstructed from adult female wood bison ear fibroblasts (bison NT) with development of embryos reconstructed from adult female cattle ear fibroblasts (cattle NT). Domestic cattle (Bos taurus) oocytes were used as recipient ooplasm for both donor cell types. In vitro fertilized (IVF) and parthenogenetic (PA) cattle embryos were used as controls. Fibroblast cultures at passages 3 to 5 confluent for 5 days were used for SCNT. Mature oocytes were enucleated, reconstructed by transfer of donor cells, and fused with an electrical stimulus of 1.5 kV cm–1 for 40 μs in 0.28 m mannitol containing 100 μm CaCl2 and MgCl2. Oocytes for parthenogenesis and following reconstruction were activated for 5 min in 5 μm ionomycin followed by 5 h in 10 μg mL–1 cycloheximide. Embryos produced by IVF, PA, and SCNT were cultured in modified synthetic oviductal fluid medium at 38.5°C in 5% CO2, 5% O2, 90% N2. Cleavage, blastocyst development to day 8, apoptosis (TUNEL assay, Roche Diagnostics, IN, USA), and total cell number were evaluated. Statistical analyses were carried out using one-way ANOVA, followed by Tukey post hoc analysis or the equivalent nonparametrical Kruskal-Wallis test. Cleavage rate was significantly (P < 0.05) higher in the IVF group than in all other groups (86.9 ± 2.9% v. 71.6 ± 4.5% to 78.1 ± 5.1%). Blastocyst rates, expressed as a percentage of cleaved embryos, were similar among all treatment groups (33.4 ± 3.3% to 39.8 ± 5.7%) except for bison NT which had significantly (P < 0.05) lower development to blastocyst (19.2 ± 5.5%). The percentages of TUNEL-positive cells among PA embryos (6.6 ± 1.5%) and bison NT embryos (6.7 ± 2.4%) were significantly (P < 0.05) higher than in IVF embryos (4.2 ± 1.0%), but similar to cattle NT embryos (5.4 ± 1.7%), which did not differ from the IVF group. Total cell number was significantly (P < 0.05) higher in the IVF group than in all other groups (133.2 ± 10.2 v. 91.2 ± 7.8 to 100.1 ± 12.9). These results confirm that in vitro-matured domestic cattle oocytes can serve as suitable recipients of wood bison somatic cells and that iSCNT may provide a possible alternative for embryo production and genetic preservation of endangered cattle species. Both the incidence of apoptotic cells and total cell number did not differ between cattle and bison NT embryos; thus other factors must play a role in the significantly decreased blastocyst development observed in bison NT embryos. This work was supported by Endangered Species Reserve Fund, Toronto Zoo, and the Canada Research Chairs program.


2007 ◽  
Vol 19 (1) ◽  
pp. 147
Author(s):  
E. Lee ◽  
K. Song ◽  
Y. Jeong ◽  
S. Hyun

Generally, blastocyst (BL) formation and embryo cell number are used as main parameters to evaluate the viability and quality of in vitro-produced somatic cell nuclear transfer (SCNT) embryos. We investigated whether in vitro development of SCNT pig embryos correlates with in vivo viability after transfer to surrogates. For SCNT, cumulus–oocyte complexes (COCs) were matured in TCM-199 supplemented with follicular fluid, hormones, EGF, cysteine, and insulin for the first 22 h and in a hormone-free medium for 18 h. Three sources of pig skin cells were used as nuclear donor: (1) skin fibroblasts of a cloned piglet that were produced by SCNT of fetal fibroblasts from a Landrace × Yorkshire × Duroc F1 hybrid (LYD), (2) skin fibroblasts of a miniature pig having the human decay accelerating factor gene (hDAF-MP), and (3) skin fibroblasts of a miniature pig with a different strain (MP). MII oocytes were enucleated, subjected to nuclear transfer from a donor cell, electrically fused, and activated 1 h after fusion. SCNT embryos were cultured in a modified NCSU-23 (Park Y et al. 2005 Zygote 13, 269–275) for 6 days or surgically transferred (110–150 fused embryos) into the oviduct of a surrogate that showed standing estrus on the same day as SCNT. Embryos were examined for cleavage and BL formation on Days 2 and 6, respectively (Day 0 = the day of SCNT). BLs were examined for their cell number after staining with Hoechst 33342. Pregnancy was diagnosed by ultrasound 30 and 60 days after embryo transfer. Embryo cleavage was not affected by donor cells (82, 81, and 72% for LYD, hDAF-MP, and MP, respectively), but BL formation was higher (P &lt; 0.05) in hDAF-MP (16%) than in LYD (9%) and MP (6%). MP showed higher (P &lt; 0.05) BL cell number (46 cells/BL) than hDAF-MP (34 cells) but did not show a difference from LYD (37 cells). LYD and MP showed higher pregnancy rates (Table 1) on Days 30 and 60, even though they showed lower BL formation in vitro. Due to a relatively small number of embryo transfers through a limited period, we could not exclude any possible effects by seasonal or operational differences. These results indicated that pregnancy did not correlate with in vitro BL formation of SCNT pig embryos but rather were affected by the source of donor cells. Table 1.In vivo development of somatic cell nuclear transfer pig embryos derived from different sources of donor cells This work was supported by the Research Project on the Production of Bio-organs (No. 200506020601), Ministry of Agriculture and Forestry, Republic of Korea.


2006 ◽  
Vol 18 (2) ◽  
pp. 125
Author(s):  
J. Estrada ◽  
E. Lee ◽  
J. Piedrahita

Donor cell quality is one of the most important factors affecting somatic cell nuclear transfer (SCNT) in mammals. Many studies have been carried out to improve the donor cell characteristics in nuclear transfer, including studies on cell type, cell cycle stage, cell passage, and handling of donor cells before the SCNT. Even though most SCNT work is done with donor cells that have been previously frozen and thawed, no studies have been conducted to evaluate the effect of the cell freezing rate on the SCNT efficiency. The objective of this experiment was to evaluate the effect of the cell freezing method on development of pig SCNT embryos in vitro. Fibroblasts were collected from a 29-day-old female fetus, suspended in DMEM-F12 + 40% fetal bovine serum (FBS) + 10% dimethyl sulfoxide (DMSO), and placed in 1.6-mL cryovials for freezing. Vials were randomly assigned to two treatments: In treatment 1, cells were frozen at a controlled rate of 1�C/min in a programmable machine (P) until -40�C, and then plunged into liquid nitrogen (LN2; -196�C). In treatment 2, the traditional system (T), vials were placed in a styrofoam box and left overnight in a freezer at -80�C. The next day samples were plunged into LN2 (196�C). For each treatment, cells were thawed and cultured until confluence before being used for SCNT. Cells were used at passages 2 and 6. Cumulus-oocyte complexes (COCs) were aspirated from slaughterhouse ovaries and cultured for 39 h in TCM 199 supplemented with 10% porcine follicular fluid (pFF), 5 �g/mL insulin, 10 ng/mL epidermal growth factor (EGF), 0.6 mM cysteine, 0.2 mM pyruvate, 25 �g/mL gentamycin and 5 �g/mL each of equine and human chorionic gonadotropin (eCG and hCG). Oocytes were stained with bisbenzimide and enucleated in manipulation media with 7.5 �g/mL cytochalasin B by removing the first polar body and metaphase plate by means of a 16-�m beveled glass pipette. Cells from each treatment were injected into the perivitelline space of recipient enucleated oocytes and fused by two DC pulses of 140 V for 50 �s in fusion media. The fusion rate was evaluated 1 h later, and reconstructed oocytes were activated by two DC pulses of 120 V for 60 �s. After activation, oocytes were placed in bicarbonate-buffered NCSU-13 with 0.4% BSA and cultured at 38.5�C, 5% CO2 in a humidified atmosphere. Embryos were observed for cell cleavage at Day 2, and blastocyst development rate and cell number counting were done at Day 7 of culture. Every experiment was repeated three times. The temperature descending rate for P was slower and more linear (1�C/min vs. 2�C/min) than for the T method. Fusion rate was not significantly affected (P < 0.05) by the freezing method when they were evaluated either individually at each passage or accumulated regardless the passage (78.9 � 3.6% vs. 79.4 � 6.3%) for P and T, respectively. The same trends were observed for cleavage (61.2 � 5.2% vs. 64.3 � 5.2%), blastocyst development (4.2 � 1.8% vs. 5.0 � 2.8%), and number of cells at the blastocyst stage (19.4 � 3.1 vs. 19.8 � 6.2) for P and T, respectively. The present findings indicate that blastocyst development after SCNT does not differ when fetal fibroblasts donor cells are frozen by the two methods tested.


2011 ◽  
Vol 23 (1) ◽  
pp. 165 ◽  
Author(s):  
D. Biswas ◽  
Y.-B. Jeon ◽  
G.-H. Kim ◽  
E.-B. Jeung ◽  
S. H. Hyun

In the present study, pig cumulus–oocyte complexes were cultured in medium supplemented with different concentrations (0, 5, 50, and 500 ng mL–1) of vascular endothelial growth factor (VEGF), and then the maturation and intracellular glutathione (GSH) concentration of oocytes were examined. In addition, the development of oocytes matured with different concentrations of VEGF after parthenogenetic activation (PA) or somatic cell nuclear transfer (SCNT) was observed. Although the maturation rate of oocytes was not affected by VEGF concentrations (81.13 ± 2.61%, 83.93 ± 1.97%, 82.14 ± 4.03%, 75.24 ± 2.68%, respectively), the intracellular GSH concentrations of oocytes matured with 5 and 50 ng mL–1 VEGF were significantly higher (12.68 ± 0.08, 12.33 ± 0.53 pMol/oocyte, respectively) than those of oocytes matured with 0 or 500 ng mL–1 VEGF (10.19 ± 0.66, 10.54 ± 0.54 pMol/oocyte, respectively). The blastocyst formation rates after PA of oocytes matured with 5 and 50 ng mL–1 VEGF were significantly higher (58.99 ± 4.70% and 54.00 ± 1.09%, respectively) than that of oocytes matured with 0 or 500 ng mL–1 VEGF (30.15 ± 4.52%, 34.79 ± 4.01%, respectively). Total cell number of PA blastocyst after oocytes matured with 5 and 50 ng mL–1 VEGF was significantly higher (83.21 ± 4.89, 78.16 ± 6.15, respectively) than that of control and 500 ng mL–1 VEGF (56.91 ± 4.78, 55.93 ± 3.89, respectively). Similarly, the blastocyst formation rate after SCNT of oocytes matured with 5 ng mL–1 VEGF was significantly higher (14.54 ± 1.42%) than that of oocytes matured without VEGF (7.95 ± 1.44%). Total cell number of SCNT blastocyst after oocytes matured with 5 ng mL–1 VEGF was significantly higher (67.83 ± 6.56) than control (48.09 ± 5.36). Fully cumulus cell expansion was significantly higher in the 5 ng mL–1 VEGF treated group (85.37 ± 0.73%) compared with the control (58.89 ± 0.88%). In conclusion, adding 5 ng mL–1 VEGF during IVM improved the developmental potential of PA and SCNT in porcine embryos by increasing the intracellular GSH level. This work was supported by a grant (#20070301034040) from BioGreen 21 program, Rural Development Administration, Republic of Korea.


2016 ◽  
Vol 28 (2) ◽  
pp. 132 ◽  
Author(s):  
K. Srirattana ◽  
J. C. St. John

Although somatic cell nuclear transfer (SCNT) is a valuable tool for producing animals for agricultural and research purposes, the resultant mixing of mitochondrial DNA (mtDNA) from the donor cell and recipient oocyte (heteroplasmy) affects embryo development and offspring survival and health. The aim of this study was to determine the effects of depleting donor cells of their mtDNA before SCNT on embryo development. mtDNA was depleted from cattle fibroblasts using 2′,3′-dideoxycytidine. mtDNA copy number in cells depleted for 30 days (0.85 ± 0.05) was significantly decreased when compared with nondepleted cells (150.12 ± 29.90; P < 0.0001, ANOVA). Moreover, mtDNA copy number in depleted cells could not be replenished after depletion for 30 days. Depleted cells and nondepleted cells were used as donor cells for SCNT. Somatic cell nuclear transfer embryos were produced by electrofusion of a single donor cell with an enucleated cow oocyte. Reconstructed oocytes were chemically activated and cultured for 7 days (nontreated embryos). Another cohort of embryos was treated with Trichostatin A (TSA), to enhance reprogramming, by activating reconstructed oocytes and culturing them in the presence of 50 nM TSA for up to 10 h. The embryos were then cultured in the absence of TSA. In nontreated groups, the fusion rates of depleted cells (78.0 ± 0.8%) were significantly lower than those of nondepleted cells (92.1 ± 1.4%; P < 0.05). No positive effect on fusion rates was found after TSA treatment. The blastocyst rate for SCNT embryos derived from depleted cells (18.7 ± 4.9%) was significantly lower than the nondepleted group (32.5 ± 3.1%; P < 0.05). Trichostatin A treatment increased blastocyst rates for SCNT embryos derived from depleted cells (32.5 ± 5.3%) to levels equivalent to those of nondepleted cells but did not have any beneficial effect on SCNT embryos derived from nondepleted cells. We have analysed blastocysts for the presence of donor cell mtDNA by high resolution melting analysis. Four out of 10 SCNT blastocysts derived from nondepleted cells were heteroplasmic, whereas others had no donor cell mtDNA. However, all 10 analysed SCNT blastocysts derived from depleted cells were homoplasmic as they harboured only oocyte mtDNA. From RNA sequencing results, TSA treatment of SCNT blastocysts derived from depleted cells increased the expression of key developmental transcription regulators and decreased expression of the mtDNA-specific replication factors, which is essential for embryo development. In conclusion, homoplasmic SCNT embryos were successfully produced by using mtDNA depleted donor cells. Trichostatin A treatment enhanced nuclear reprogramming efficiency in SCNT embryos derived from depleted cells. This work was supported by MitoStock Pty. Ltd., Australia.


Zygote ◽  
2010 ◽  
Vol 18 (2) ◽  
pp. 93-101 ◽  
Author(s):  
S. Kim ◽  
J.H. Kim ◽  
E. Lee ◽  
Y.W. Jeong ◽  
M.S. Hossein ◽  
...  

SummaryThis study was aimed to establish embryonic stem (ES)-like cells from blastocysts derived from somatic cell nuclear transfer (SCNT) in pig. Somatic cells isolated from both day-30 fetus and neonatal cloned piglet were used for donor cells. A total of 60 blastocysts (46 and 14 derived from fetal and neonatal fibroblast donor cells, respectively) were seeded onto a mitotically inactive mouse embryonic fibroblast (MEF) monolayer and two ES-like cell lines, one from each donor cell type, were established. They remained undifferentiated over more than 52 (fetal fibroblast-derived) and 48 (neonatal fibroblast-derived) passages, while retaining alkaline phosphatase activity and reactivity with ES specific markers Oct-4, stage-specific embryonic antigen-1 (SSEA-1), SSEA-4, TRA-1–60 and TRA-1–81. These ES-like cells maintained normal diploid karyotype throughout subculture and successfully differentiated into embryoid bodies that expressed three germ layer-specific genes (ectoderm: β-III tubulin; endoderm: amylase; and mesoderm: enolase) after culture in leukemia inhibitory factor-free medium. Microsatellite analysis confirmed that they were genetically identical to its donor cells. Combined with gene targeting, our results may contribute to developing an efficient method for producing transgenic pigs for various purposes.


2006 ◽  
Vol 18 (2) ◽  
pp. 123
Author(s):  
Y. H. Choi ◽  
Y. G. Chung ◽  
D. D. Varner ◽  
K. Hinrichs

Only one horse foal produced from adult somatic cell nuclear transfer has been reported in the scientific literature (Galli et al. 2003 Nature 425, 680); a second foal from the same laboratory was reported in the popular press in 2005. In these reports, the blastocyst rates were 3 and 17%, and efficiency to birth of a live foal from total reconstructed oocytes was 0.1 and 0.5%, respectively. In cattle, roscovitine treatment of donor cells has been associated with a decrease in blastocyst development, but an increase in live births (Gibbons et al. 2002 Biol. Reprod. 66, 895-900). The present study was performed to determine the effect of roscovitine treatment of donor cells on blastocyst production after equine nuclear transfer and to evaluate the viability of pregnancies established via this treatment. In Experiment 1, fibroblasts were either grown to confluence or treated with 15 �g/mL roscovitine, for 24 h. Enucleated in vitro-matured oocytes were reconstructed by direct injection of fibroblasts using a piezo drill. Recombined oocytes were activated by injection of stallion sperm extract, followed by culture in the presence of 2 mM 6-DMAP for 4 h. They were then placed in culture in DMEM/F-12 with 10% fetal bovine serum (FBS) under mixed gas for 8 days and evaluated for blastocyst development. In Experiment 2, oocytes recombined with either confluent or roscovitine-treated donor cells were activated as above either alone or with the addition of 10 �g/mL cycloheximide at the time of 6-DMAP treatment. Resulting blastocysts from Experiment 2 were transferred transcervically to the uteri of recipient mares. One embryo was transferred per mare. In Experiment 1, there was no difference in rates of cleavage (73-19%) or blastocyst development between confluence and roscovitine treatments (2/55, 3.6% vs. 2/56, 3.6%, respectively). In Experiment 2, there was no significant difference in rates of cleavage (78-18%) or blastocyst development (0-1%; 4/105, 0/104, 0/106, 2/108) among donor cell or activation treatments. Six blastocysts were transferred to mares: two from confluent donor cells and four from roscovitine-treated donor cells. One mare, which received an embryo from the roscovitine donor/6-DMAP treatment, established pregnancy after transfer. The pregnancy continued normally and the mare delivered a colt with minimal assistance on Day 389. Typing for 13 equine microsatellites confirmed that the colt was of the same DNA type as the donor fibroblasts. The colt has grown and developed normally. Results of these studies show that roscovitine treatment of equine donor cells does not negatively affect the proportion of recombined oocytes that progress to the blastocyst stage. A viable colt resulted from an embryo produced with roscovitine-treated donor cells. More work is needed on methods to increase blastocyst rates after nuclear transfer in this species. This work was supported by the Link Equine Research Endowment Fund, Texas A&M University.


2011 ◽  
Vol 23 (1) ◽  
pp. 126
Author(s):  
Y. Kaedei ◽  
A. Fujiwara ◽  
F. Tanihara ◽  
Z. Namula ◽  
V. L. Vien ◽  
...  

Interspecies somatic cell nuclear transfer (iSCNT) is an invaluable tool for studying nucleous-cytoplasm interactions, and may provide an alternative for cloning endangered animals, whose oocytes are difficult to obtain. Using readily available oocytes from domestic/farm animals as recipients for iSCNT would greatly benefit ongoing research on somatic cell reprogramming. However, little information is available concerning the development of canine iSCNT embryos reconstructed with bovine oocyte cytoplasm. In the first experiment, we investigated the influence of donor cell type on the development of canine iSCNT embryos reconstructed with enucleated bovine oocytes. Canine mammary gland tumour (MGT) cells and cumulus cells were used as donor cell. The bovine oocytes matured for 22 h were enucleated by the micromanipulator, and the donor cells were transferred into the perivitelline space adjacent to the plasma membrane of the oocyte. The couples were fused and activated simultaneously with a single DC pulse of 2.3 kV cm–1 for 30 μs, using an electro cell fusion generator. The reconstructed embryos were cultured for 72 h in the mSOF medium supplemented with 0.4% BSA. After 72 h of culture, only cleaved embryos were further co-cultured with bovine cumulus cells in mSOF supplemented with 5% fetal bovine serum (FBS) for an additional 5 days. In the second experiment, we examined the effects of serum type on the development of canine iSCNT embryos. The embryos reconstructed with canine cumulus cells were co-cultured with canine cumulus cells in mSOF supplemented with 5% FBS, and canine oestrous and diestrous serum for 5 days after 72 h of culture with 0.4% BSA. Data were analysed by chi-square analysis with a Yates’ correction. More than 75% of the canine somatic cells successfully were fused with bovine enucleated oocytes following electrofusion, irrespective of the types of the donor cells. There were no significant differences in the cleavage rates of iSCNT embryos between the cumulus cell and MGT cell (66.2% v. 62.6%). Although none of the embryos reconstructed with MGT cells (n = 123) developed to the 16-cell stage, 6% of embryos with cumulus cells (n = 133) reached at least the 16-cell stage. There were no significant differences in the cleavage rates of iSCNT embryos among the types of serum. The iSCNT embryos could not develop to the blastocyst stage, irrespective of the type of donor cell and serum. In conclusion, our results indicate that the bovine oocytes partly supported the remodelling and reprogramming of the canine somatic cell nuclei, but they were unable to support the development to the blastocyst stage of canine iSCNT embryos. Moreover, the development to the late embryonic stage of iSCNT embryos may be influenced by the type of donor cell but not serum.


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