scholarly journals 4CHROMOSOMAL STABILITY OF AFRICAN WILD CAT (FELIS SILVESTRIS LIBICA) SOMATIC CELLS AND CLONED EMBRYOS

2004 ◽  
Vol 16 (2) ◽  
pp. 124 ◽  
Author(s):  
A.M. Giraldo ◽  
M.C. Gomez ◽  
B.L. Dresser ◽  
R.F. Harris ◽  
A.L. King ◽  
...  

Nuclear transfer (NT) procedures are generally inefficient and chromosomal abnormalities have been suggested as one causative factor. Embryos derived by somatic cell NT show a high incidence of aneuploidy, which seems to be reflective of the donor cell line with high chromosomal abnormalities (Bureau et al., 2003, Theriogenology 59, 239). Also, aneuploidies in some cell lines increase progressively with the number of passages (Denning et al., 2001, Cloning 3, 221–231). Therefore, the aim of the present study was to analyze the chromosomal stability of donor cells at different passages as well as that of reconstructed embryos derived from these cells. A primary culture of African wild cat (AWC) fibroblast cells was established from a skin sample and cultured until cells stopped dividing at passage 9. Chromosome numbers were determined in cells using a karyotyping technique (Iwasaki et al., 1992 J Exp Zool 261, 79–85) at passages 1 and 3 through 9. At passages 1, 3, 4 and 9, NT of AWC fibroblast cells into domestic cat cytoplasts was done (Gomez et al., 2003, Biol Reprod 69, 1032–1041). Reconstructed blastocysts were treated with colcemid (0.28μgmL−1) and fixed for karyotyping to evaluate chromosome numbers in the blastomeres. Blastomere metaphases were often highly contracted or overlapping, so that only 1 to 7 sets of metaphase chromosomes per embryo were spread sufficiently to allow determination of ploidy. No attempt to produce NT embryos using cells at passages 5 through 8 was done because the percentages of aneuploidies of these passages were not significantly different (P>0.05). Data were analyzed by chi-square test (P<0.05). As shown in the Table, the percentage of aneuploidy in the somatic cells increased progressively with duration of culture. Furthermore, the percentage of chromosomal abnormalities in reconstructed embryos was similar to that of the cells from which they were derived. Accordingly, for future NT, we propose to use donor cells at early passages when the percentage of cells with chromosomal abnormalities is still relatively low. Research was funded partially by the John & Shirley Davies Foundation. Chromosomal abnormalities in AWC cells and cloned embryos

2009 ◽  
Vol 21 (1) ◽  
pp. 125
Author(s):  
M. Skrzyszowska ◽  
M. Samiec ◽  
W. Mlodawska ◽  
J. Kochan ◽  
A. Okolski ◽  
...  

The purpose of our study was to determine the in vitro developmental competences of equine NT embryos reconstructed with adult dermal fibroblast cells. Frozen/thawed fibroblast cells, whose mitotic cycle had been synchronized at G1/G0 stages through a contact inhibition of their migration and proliferative activity under total confluency, were used as a source of nuclear donor cells in the somatic cell cloning procedure. In vitro-matured oocytes were used as recipient cells for fibroblast cell nuclei. The compact cumulus–oocyte complexes (cpCOCs) were collected from abattoir-derived mare ovaries and selected for in vitro maturation. The cpCOCs were cultured in TC-199 medium supplemented with 5 mU mL–1 follicle-stimulating hormone (FSH), 10% fetal bovine serum (FBS) and 75 μg mL–1 kanamycin monosulfate (kanamycin A) for 30 h at 38.2°C in a 100% water-saturated atmosphere of 5% CO2 and 95% air. Cumulus-denuded in vitro-matured oocytes were incubated in the maturation medium supplemented with 0.4 μg mL–1 demecolcine for 40 min. The treated oocytes were subsequently transferred into TC-199 medium containing 4 mg mL–1 BSA-V and 5 μg mL–1 cytochalasin B. Metaphase chromosomes, which had been allocated into the chemically-induced protrusion of the plasma membrane, were removed microsurgically. The chemically-assisted enucleation was accomplished by gently aspirating the ooplasmic cone, which contained the condensed chromosome mass, with the aid of a beveled micropipette. The single nuclear donor cells were inserted into perivitelline space of previously enucleated oocytes. Fibroblast cell-ooplast couplets were fused with two consecutive DC pulses of 2.4 kV cm–1 for 30 μs. After a 1.5-h delay, nuclear transfer-derived oocytes were chemically activated by exposure to 5 μm L–1 calcium ionomycin for 5 to 7 min, followed by their incubation in B2 medium with addition of 2 mm L–1 6-dimethylaminopurine (6-DMAP) for 4 h. Reconstructed embryos were in vitro cultured in B2 medium for 2 days. Afterwards, cleaved embryos were co-cultured with Vero cells in B2 medium supplemented with 10% FBS for 5 to 6 days up to morula/blastocyst stages. From among 88 in vitro cultured cpCOCs, 55 (62.5%) acquired meiotic nuclear and cytoplasmic maturity state after reaching the Metaphase II stage. A total of 55 enucleated oocytes underwent reconstruction and 44/55 (80.0%) were successfully fused with nuclear donor cells. Out of 44 cultured NT embryos, 21 (47.7%) were cleaved. The frequencies of cloned embryos that reached the morula and blastocyst stages were 6/44 (13.6%) and 3/44 (6.8%), respectively. In conclusion, the cell nuclei of in vitro cultured adult dermal fibroblast cells, which had undergone the contact inhibition, were able to direct the preimplantation development of equine cloned embryos to morula and blastocyst stages. This work was supported by the Scientific Net of Animal Reproduction Biotechnology.


Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 4287-4287
Author(s):  
Laurence K. Benattar ◽  
Laurence Bouffard ◽  
Lionel J. Coignet

Abstract We report here the case of a bone marrow transplant (BMT) patient who received a graft from her 1-year-old HLA-identical brother for severe aplastic anemia (AA) with severe thrombopenia at the age of 4, followed by myelodysplasia at the age of 6 that transformed to AREBt/AML type M6 at the age of 7. She died at the age of 8. Two years after the BMT, the brother developed hypoplasia that rapidly transformed to AML-M2 and he died rapidly during chemotherapy induction. Cytogenetic results showed that the brother initially developed an AML-M2 with a t(16;21) translocation and, 3 years later, the patient developed an AREBt/AML-M6 with a monosomy 7 and a donor profile (45,XY,−7). Retrospective examinations did not allow the detection of the t(16;21) in any samples of the patient nor monosomy 7 in any available sample from her brother. This observation shows that the same cells (the donor cells) in another microenvironment, even HLA-identical, can transform to different acute leukemia types with different chromosomal abnormalities. In both, the chromosomal abnormalities seem to appear at a late stage of the disease and can be considered a secondary event. Familial MDS/AML with monosomy 7 are well described: heterozygous deletion and nonpreferential deletion of parental chromosome suggest that the inherited gene(s) might not be located on chromosome 7. Other familial hematological disorders such as familial platelet disorders present a AML1 translocation or mutation. In our case, on one hand, two hematological disorders in siblings (one AA and one AML at diagnosis) can be considered a familial case even if the past medical history of the other members of the family is unremarkable. On the other hand, the same cells (the brother’s cells) have provided a translocation involving AML1 in the donor and a monosomy 7 in the recipient, the two genetic abnormalities being involved in familial hematological disorders. We could hypothesize that those two events might have been induced by the same inherited gene(s) that could be responsible at the same time for familial monosomy 7 and for other familial hematological disorders.


2013 ◽  
Vol 13 (2) ◽  
pp. 275-293 ◽  
Author(s):  
Marcin Samiec ◽  
Maria Skrzyszowska ◽  
Jolanta Opiela

Abstract Somatic cell cloning efficiency is determined by many factors. One of the most important factors is the structure-functional quality of nuclear donor cells. Morphologic criteria that have been used to date for qualitative evaluation of somatic cells may be insufficient for practical application in the cloning. Biochemical and biophysical changes that are one of the earliest symptoms in the transduction of apoptotic signal may be not reflected in the morphologic changes of somatic cells. For this reason, adult cutaneous or foetal fibroblast cells that, in our experiments, provided the source of genomic DNA for the cloning procedure had been previously analysed for biochemical and biophysical proapoptotic alterations with the use of live-DNA (YO-PRO-1) and plasma membrane (Annexin V-eGFP) fluorescent markers. In Groups IA and IB, the generation of nucleartransferred (NT) embryos using non-apoptotic/non-necrotic contact-inhibited or serum-starved adult cutaneous fibroblast cells yielded the morula and blastocyst formation rates of 125/231 (54.1%) and 68/231 (29.4%) or 99/237 (41.8%) and 43/237 (18.1%), respectively. In Groups IIA and IIB, the frequencies of embryos reconstituted with non-apoptotic/non-necrotic contact-inhibited or serum-starved foetal fibroblast cell nuclei that reached the morula and blastocyst stages were 171/245 (69.8%) and 97/245 (39.6%) or 132/227 (58.1%) and 63/227 (27.8%), respectively. In conclusion, contact inhibition of migration and proliferative activity among the subpopulations of adult dermal fibroblast cells and foetal fibroblast cells resulted in considerably higher morula and blastocyst formation rates of in vitro cultured cloned pig embryos compared to serum starvation of either type of fibroblast cell line. Moreover, irrespective of the methods applied to artificially synchronize the mitotic cycle of nuclear donor cells at the G0/G1 phases, developmental abilities to reach the morula/blastocyst stages were significantly higher for porcine NT embryos that had been reconstructed with non-apoptotic/non-necrotic foetal fibroblast cells than those for NT embryos that had been reconstructed with non-apoptotic/non-necrotic adult dermal fibroblast cells. To our knowledge, the generation of cloned pig embryos using abattoir-derived oocytes receiving cell nuclei descended from contact-inhibited or serum-deprived somatic cells undergoing comprehensive vital diagnostics for the absence of biochemical and biophysical proapoptotic alterations within their plasmalemmas has not been reported so far.


2007 ◽  
Vol 19 (1) ◽  
pp. 152
Author(s):  
K. Naruse ◽  
Y. M. Shin ◽  
Y. S. Quan ◽  
C. S. Park ◽  
D. I. Jin

Streptolysin O (SLO) is known to bacterial proteins that form very large pores in the plasma membrane of mammalian cells. SLO has been used in the delivery of proteins into living cells following permeabilization. The objective of this study was to investigate the effect of permeabilization of donor cells using SLO on in vitro development of porcine reconstructed embryos. Porcine fetal fibroblast cells were treated with Ca2+-free DMEM medium containing 200 ng mL−1 of SLO for 50 min before or after trypsinization. Those SLO-treated donor cells were injected into enucleated oocytes, fused with 2 DC pulses (1.2 kV cm−1, 30 µs) and cultured in procine zygote medium-3 (PZM-3) for 6 days. In vitro development of the reconstructed embryos was examined. SLO treatment after trypsinzation significantly increased (P < 0.05) the percentage of fusion rates and blastocyst developmental rates compared with that before trypsinization or in the nontreated group. Additionally there were no significant differences in fusion rates, cleavage rates, blastocyst developmental rates, and total cell number of blastocysts between the SLO-treated group before trypsinzation and the nontreated group. Next, after the trypsinzation treatment, fetal fibroblast cells were incubated in Ca2+-free DMEM containing 200 ng mL−1 of SLO for 0, 30, 50, and 70 min and SLO-treated donor cells were also tested for fusion rate and developmental capability following reconstruction. The 50-min group of SLO-treated cells significantly increased (P < 0.05) the percentage of fusion rates (90.6 vs. 77.6, 85.4, and 78.5%) and blastocyst developmental rates (24.7 vs. 13.5, 11.2, and 13.5%) compared with the other groups (Table 1). However, there was no significant difference in the total cell number of blastocysts among SLO-treated groups. Although cleavage rates the in SLO-treated groups were not significantly different from those of the nontreated group, there the cleavage rates were slightly in SLO-treated groups. In conclusion, permeabilization of porcine fetal fibroblast cells with SLO improves the fusion rates and in vitro development of porcine reconstructed embryos. Table 1.Effects of SLO treatment of fetal fibroblasts by different exposure times on in vitro development of porcine reconstructed embryos


2010 ◽  
Vol 22 (1) ◽  
pp. 187
Author(s):  
M. K. Jena ◽  
D. Malakar ◽  
A. K. De ◽  
S. Garg ◽  
Y. S. Akshey

The study was carried out to see the developmental efficiency of handmade cloned goat embryos with 3 different media: RVCL (Research Vitro Cleave, Cook, Brisbane, Australia), EDM (Embryo Development Media) and modified SOF (mSOF) and 2 types of donor cells: fetal fibroblast and adult fibroblast. Oocytes were isolated from abattoir goat ovaries, matured in maturation medium, and incubated in 5% CO2 in air at 38.5°C for 24 h. Then, the oocytes were made cumulus free by treatment with hyaluronidase (0.5 mg mL-1) and zona free by pronase (2 mg mL-1). Protrusion cone formation in oocytes was found 95 to 100% in T20 (TCM-199 + 20% FBS). The zona-free oocytes were bisected with an ultra-sharp micro blade on the basis of visible protrusion cones on the surface of oocytes using T20 medium containing 2.5 μg mL-1 cytochalasin-B. Fetal and adult fibroblast cells were used from confluent monolayer at passage 5 after trypsinizing in 0.25% trypsin-EDTA. One somatic cell was attached with one enucleated demioocyte by phytohemagglutinin and further fused with another enucleated demioocyte through electric pulse with a combination of alternating current (4 V) and direct current (2.10 kV cm-1 for 5 μs with a single pulse) in fusion medium (0.3 M mannitol, 0.1 mM MgCl2, 0.05 mM CaCl2, and 3 mg mL-1 BSA). Then, triplets were chemically activated with 5 μM Ca ionophore for 5 min and 2 mM 6-DMAP for 4 h and cultured in the 3 media. Cleavage and morulae formation were observed at Day 7 from 183 triplets with fetal fibroblasts as donor cells in media RVCL (78.60 ± 2.23, 38.97 ± 2.1), mSOF (72.62 ± 1.89, 33.81 ± 1.9), and EDM (73.96 ± 1.66, 26.20 ± 2.04), respectively. Simultaneously, cleavage and morulae formation were observed at Day 7 from 203 triplets with adult fibroblasts as donor cells in media RVCL (73.97 ± 3.57, 33.14 ± 2.68), mSOF (76.22 ± 4.36, 26.15 ± 0.99), and EDM (65.97 ± 3.11, 20.78 ± 2.77), respectively. Among the 3 media, morulae formation was significantly higher in RVCL. Hence, in the subsequent experiment, RVCL medium was used exclusively in culture for 172 triplets. Cleavage and morulae formation at Day 7 was not significantly different (P < 0.05) in 2 types of donor cells; fetal fibroblasts (77.46 ± 3.65, 38.70 ± 2.66) and adult fibroblasts (75.74 ± 3.04, 33.77 ± 1.43), respectively. The data were analyzed using SYSTAT 7.0 (Systat, SPSS Inc., Chicago, IL, USA) after arcsine transformation, one-way ANOVA followed by Fisher’s LSD test. PCR analysis was performed with highly polymorphic 286-bp fragment of MHC-II DRB gene of cloned embryo and its donor cell. Similar bands were observed in both the cloned embryos and fibroblast cells in agar gel electrophoresis. In conclusion, development of handmade cloned embryos was higher in RVCL medium compared with the other two media tested, and efficiency of morulae formation was similar in both types of donor cells. Further study is required to optimize blastocyst production.


Reproduction ◽  
2005 ◽  
Vol 129 (2) ◽  
pp. 245-249 ◽  
Author(s):  
X J Yin ◽  
H S Lee ◽  
Y H Lee ◽  
Y I Seo ◽  
S J Jeon ◽  
...  

This work was undertaken in order to study the developmental competence of nuclear transfer (NT ) into cat embryos using fetal fibroblast and adult skin fibroblast cells as donor nuclei. Oocytes were recovered by mincing the ovaries in Hepes-buffered TCM199 and selecting the cumulus oocyte complexes (COCs) with compact cumulus cell mass and dark color. Homogenous ooplasm was cultured for maturation in TCM199+10% fetal bovine serum (FBS) for 12 h and used as a source of recipient cytoplast for exogenous somatic nuclei. In experiment 1, we evaluated the effect of donor cell type on the reconstruction and development of cloned embryos. Fusion, first cleavage and blastocyst developmental rate were not different between fetal fibroblasts and adult skin cells (71.2 vs 66.8; 71.0 vs 57.6; 4.0 vs 6.1% respectively; P < 0.05). In experiment 2, cloned embryos were surgically transferred into the oviducts of recipient queens. One of the seven recipient queens was delivered naturally of 2 healthy cloned cats and 1 stillborn from fetal fibroblast cells of male origin 65 days after embryo transfer. One of three recipient queens was delivered naturally of 1 healthy cloned cat from adult skin cells of female origin 65 days after embryo transfer. The cloned cats showed genotypes identical to the donor cell lines, indicating that adult somatic cells can be used for feline cloning.


2007 ◽  
Vol 19 (1) ◽  
pp. 150 ◽  
Author(s):  
K. Miyamoto ◽  
M. Ohnuki ◽  
N. Minami ◽  
M. Yamada ◽  
H. Imai

Revealing an adequate cell state for nuclear reprogramming is essential to achieve efficient production of cloned embryos and animals. Previous reports suggest that nuclei from undifferentiated cells such as blastomeres or embryonic stem cells can support efficient development of cloned embryos to term. In recent years, differentiated somatic cells are frequently used for donor cells because of ease of preparation and application for genetic modification. The efficiency of the somatic cell nuclear transfer (SCNT) is still extremely low. We hypothesized that somatic cells that had been reprogrammed to dedifferentiated states before SCNT might support higher developmental ability of SCNT embryos. To test this hypothesis, porcine fibroblast cells were treated with Xenopus egg extracts, and the extract-treated cells (ETCs) were used as donor cell for SCNT to examine their ability to support early embryonic development. Xenopus egg extracts were prepared from activated S-phase eggs. Porcine fibroblast cells (106/mL) were permeabilized by 500 ng mL-1 of Streptolysin O and were incubated in the egg extracts with the energy-regenerating system for 2 hours at 23�C. After the extract treatment, permeabilized membranes were resealed in DMEM containing 2 mM CaCl2. The ETCs were fused with porcine enucleated oocytes and simultaneously activated. The reconstructed embryos were cultured in PZM-3 medium for 7 days. All statistical differences were analyzed by ANOVA. Reprogramming of ETCs was evaluated on changes of chromatin states and gene expression. Chromatin-binding proteins of ETCs were separated and analyzed on SDS-PAGE. Some proteins were incorporated onto and/or released from chromatins after the extract treatment. Especially, Xenopus egg-specific linker histone B4 was assembled on chromatins. Non-permeabilized control cells did not show these protein exchanges. Deacetylation of histone H3 lysine9 was detected in half number of ETCs in an ATP-dependent manner. In contrast, a high population of histone H3-acetylated cells was observed in buffer-treated cells as well as cells before the extract treatment. The pluripotent marker gene expression, such as OCT4 and SOX2, was also observed in ETCs after culture. The gene expression of these genes was not detected in non-treated cells. These results indicate that the extract treatment induces or triggers a part of dedifferentiation of somatic cells. These ETCs were used as donor cell for SCNT, and reconstructed cloned embryos were cultured. SCNT embryos showed no significant difference in cleavage rates and developmental rates to the blastocyst stage (25%) compared with non-treated control cells (26%). However, the total cell number of embryos at the blastocyst stage was significantly higher in SCNT embryos from ETCs compared with those of control cells (62 � 7 vs. 43 � 2, respectively; P &lt; 0.05). These results indicate that the extract treatment before nuclear transfer may stimulate cell proliferation of SCNT embryos but not improve early development. More studies, however, are needed to investigate their developmental ability to term.


2011 ◽  
Vol 23 (1) ◽  
pp. 244
Author(s):  
R. Dutta ◽  
D. Malakar ◽  
K. Khate ◽  
J. Akshay

The handmade cloning technique has been a relatively recent addition in the field of nuclear transfer. In the present study, attempts were made to efficiently derive stem cells from handmade cloned (HMC) embryos in goat using adult fibroblast cells, embryonic stem (ES) cells, and lymphocytes as donor cells, and to characterise the derived putative nuclear transfer ES (ntES) cells for their stemness. Efficiency of the donor cells for nuclear transfer was also compared, and an overall cleavage and morula formation rates of 62.44 ± 3.9% and 35.30 ± 3.86%, 75.45 ± 3.92% and 45.84 ± 3.86%, and 56.38 ± 3.92% and 29.09 ± 3.86% were obtained from adult fibroblasts, ES cells, and lymphocytes, respectively. A significant difference was found between ES cells and the other 2 donor cells in terms of cleavage and morula formation. However, no such difference existed between fibroblasts and lymphocyte donor cells. Stem cell colonies were successfully derived from HMC embryos obtained from all 3 different donor cells. The rate of primary colony formation was 61.66 ± 4.62% for fibroblast-donor-cell-derived embryos. This rate was 59.91 ± 4.62% for ES-donor-cell-derived embryos and 62.49 ± 4.62% for lymphocyte-donor-cell-derived embryos. The putative ntES colonies were positively characterised for TRA-1-60, TRA-1-81, SSEA-1, SSEA-4, OCT-4, SOX-2, and Nanog by immunocytochemistry and RT-PCR. Results indicated that ES cells had better efficiency as donor cells in cloned embryo production than did adult fibroblasts and lymphocytes. The finding also suggested that terminally differentiated cell-like lymphocytes can also be reprogrammed. Moreover, there was no difference between the different donor-cell-derived HMC embryos in terms of ntES cell derivation. The study has established an efficient protocol for putative ntES cell derivation from HMC embryos. This could be of substantial significance because patient-specific ntES cells have proven therapeutic significance. The authors acknowledge N.D.R.I for the financial and infrastructural assistance.


Reproduction ◽  
2001 ◽  
pp. 801-808 ◽  
Author(s):  
JL Liu ◽  
MK Wang ◽  
QY Sun ◽  
XR Zhang ◽  
LK Jiang ◽  
...  

In mammals, preparation of donor cells for somatic nuclear transfer is very important because the character of the donor cell directly affects the efficiency and outcome of transfer. The protocols used most commonly for donor preparation are (i) disaggregating cells from fresh tissue 1-2 h before micromanipulation or (ii) trypsinizing cultured cells temporarily, after special treatments for 3-8 days (for example, serum starvation). In this study, a new simple protocol was designed, whereby the donor cells (cumulus cells) used in bovine somatic nuclear transfer were refrigerated. In brief, cultured cells at 80-100% confluency were detached using trypsin, washed by centrifugation, aliquoted into different vials and refrigerated at 4 degrees C. The density of viable cells was decreased after day 1 of refrigeration; however, the rate of decrease tended to slow down with increasing duration of refrigeration. Cells refrigerated for 15 days were seeded at a density of 5 x 10(4) ml(-1) and reached 70% confluency after day 2 of culture. Most cells had the normal number of chromosomes (2n = 60). Cells chilled at 4 degrees C for different durations were removed from refrigeration and immediately subjected to micromanipulation. The in vitro development of reconstructed embryos (fusion rates, cleavage rates, morula and blastocyst rates) indicated that there were no significant differences among treatment groups regardless of the duration of refrigeration (0-2 weeks) of the donor cells. Reconstructed embryos were transferred into the uteri of recipient cows. No significant differences were observed in established early pregnancies between embryos derived from the non-refrigerated donor cells and those derived from refrigerated donor cells. This study indicates that refrigeration of donor cells for 1-2 weeks is a feasible protocol for preparing donor cells for bovine somatic nuclear transfer, and does not compromise development in vitro and early development in vivo.


Zygote ◽  
2008 ◽  
Vol 16 (3) ◽  
pp. 223-227 ◽  
Author(s):  
Gang Zhang ◽  
Qing-Yuan Sun ◽  
Da-Yuan Chen

SummaryIn this study, C57BL/6 adult male mouse ear fibroblast cells and Kunming mouse M2 oocytes were used as donors and recipients, respectively, to investigate the effect of passage number on donor cells and electrofusion times on the in vitro development of nuclear transfer (NT) embryos. The results demonstrated firstly that when the ear fibroblast cells from either 2–4, 5–7 or 8–10 passages were used as donors, respectively, to produce NT embryos, the number of passages undergone by the donor cells had no significant effect on the in vitro development of NT embryos. The developmental rates for morula/blastocyst were 15.2, 13.3 and 14.0%, respectively, which were not significantly difference (p > 0.05). Secondly, when the NT embryos were electrofused, there was no significant difference between the fusion ratio for the first electrofusion and the second electrofusion (p > 0.05). The developmental rates of the 2-cell and 4-cell stages that had undergone only one electrofusion, however, were significantly higher than those that had had two electrofusions (65.7% compared with 18.4% and 36.4% compared with 6.1%; p < 0.01), furthermore the NT embryos with two electrofusions could not develop beyond the 4-cell stage. This study suggests that this protocol might be an alternative method for mouse somatic cloning, even though electrofusion can exert negative effects on the development of NT embryos.


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