180 IDENTIFICATION AND QUANTIFICATION OF DIFFERENTIALLY REPRESENTED TRANSCRIPTS IN PREIMPLANTATION BOVINE EMBRYOS

2008 ◽  
Vol 20 (1) ◽  
pp. 169 ◽  
Author(s):  
C. E. McHughes ◽  
G. K. Springer ◽  
L. D. Spate ◽  
R. Li ◽  
R. J. Woods ◽  
...  
Keyword(s):  
Relative Abundance ◽  
Nuclear Transfer ◽  
Developmental Stages ◽  
Reproductive Technologies ◽  
Blastocyst Stage ◽  
Preimplantation Embryos ◽  
Cell Stage ◽  
Production Techniques

Identification of transcripts that are present at key development stages of preimplantation embryos is critical for a better understanding of early embryogenesis. To that end, this project had two goals. The first was to characterize the relative abundance of multiple transcripts during several developmental stages, including metaphase II-stage oocytes (MPII), and 2-cell-stage (2-cell), precompact morula (PCM), and in vitro-produced blastocyst-stage (IVTBL) embryos. The second was to characterize differences in the relative abundance of transcripts present in in vivo- (IVVBL), in vitro-, and nuclear transfer-produced (NTBL) blastocysts. It was our hypothesis that the identification of differentially represented transcripts from these stages would reveal not only developmentally important genes, but also genes that might be aberrantly expressed due to embryo production techniques. Individual clusters from a large bovine EST project (http://genome.rnet.missouri.edu/Bovine/), which focused on female reproductive tissues and embryos, were compared using Fisher's exact test weighted by number of transcripts per tissue by gene (SAS PROC FREQ; SAS Institute, Inc., Cary, NC, USA). Of the 3144 transcripts that were present during embryogenesis, 125 were found to be differentially represented (P < 0.01) in at least one pairwise comparison (Table 1). Some transcripts found to increase in representation from the MPII to the 2-cell stage include protein kinases, PRKACA and CKS1, as well as the metabolism-related gene, PTTG1. These same transcripts were also found to decrease in representation from the 2-cell to the PCM stage. RPL15 (translation) and FTH1 (immune function) were both more highly represented in the PCM than in the 2-cell stage. From PCM to IVTBL, we saw an increase in RPS11, another translation-related transcript. When comparing blastocyst-stage embryos from different production techniques, several transcripts involved in energy production (e.g., COX7B and COX8A) were found to be more highly represented in the NTBL than in the IVTBL. COX8A was also more highly represented in the IVVBL than in the IVTBL. By investigating these differentially represented transcripts, we will be able to better understand the developmental implications of embryo manipulation. We may also be able to better develop reproductive technologies that lead to in vitro- and nuclear transfer-derived embryos which more closely follow a normal program of development. Table 1. Differentially represented transcripts between developmental stages

Consumption of amino acids by bovine preimplantation embryos

1996 ◽  
Vol 8 (6) ◽  
pp. 945 ◽  
Author(s):  
RJ Partridge ◽  
HJ Leese
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Developmental Stages ◽  
Blastocyst Stage ◽  
Preimplantation Embryos ◽  
Cell Stage ◽  
Amino Acid Requirement ◽  
Zygote Stage

Bovine embryos produced in vitro from the putative zygote stage to the blastocyst stage, and blastocysts freshly flushed from the uterus, were cultured in a physiological mixture of amino acids. Depletion of amino acids from the medium and, in a few cases, their appearance, was measured by high performance liquid chromatography. Amino acids were depleted at widely differing rates. The depletion of amino acids was higher when embryos at later developmental stages were cultured, implying an increase in amino acid requirement with development. Threonine was the only amino acid to be depleted at all stages of development; depletion increased from 0.18 +/- 0.07 pmol embryo-1 h-1 at the putative zygote stage to 1.96 +/- 0.49 pmol embryo-1 h-1 at the blastocyst stage. Glutamine was depleted at the putative zygote stage and the 4-cell stage (0.76 +/- 0.05 and 0.94 +/- 0.10 pmol embryo-1 h-1 respectively), but was not significantly depleted at the later stages. Alanine was the only amino acid that appeared consistently in the medium and its production increased progressively throughout development. Aspartate, glutamate, threonine and lysine were depleted significantly by blastocysts derived both in vitro and in vivo; the embryos in vivo also depleted arginine, phenylalanine, isoleucine and tyrosine. These results indicate that individual amino acids are depleted at different rates by bovine preimplantation embryos and suggest that amino acid requirements change during development.

131 GENE SILENCING IN BOVINE ZYGOTES: SIRNA TRANSFECTION v. MICROINJECTION

2010 ◽  
Vol 22 (1) ◽  
pp. 224 ◽  
Author(s):  
C. M. O'Meara ◽  
J. D. Murray ◽  
J. F. Roche ◽  
S. Mamo ◽  
E. Gallagher ◽  
...  
Keyword(s):  
Gene Silencing ◽  
Embryo Development ◽  
Relative Abundance ◽  
Gene Function ◽  
Developmental Stages ◽  
Analysis Data ◽  
Blastocyst Stage ◽  
Cell Stage ◽  
E Cadherin

Ribonucleic acid interference (RNAi) has become an effective tool for studying gene function in a variety of cells. The objective of this study was to compare the efficiency of gene silencing when siRNA were introduced into bovine zygotes by microinjection (as done previously; Tesfaye D et al. 2007 Mol. Reprod. Dev. 74, 978-988) v. a novel method of transfection in terms of gene knockdown and embryo development. For microin-jection, in vitro-produced bovine zygotes (16 h post insemination) were randomly assigned to 1 of 3 groups over 2 experiments. In Experiment 1, E-cadherin siRNA was injected at 100 μM (n = 168) and compared with PBS-injected (n = 180) and noninjected controls (n = 152). In Experiment 2, E-cadherin siRNA was injected at 375 μM (n = 154) and compared with PBS-injected (n = 136) and noninjected controls (n = 151). Embryos were subsequently cultured in vitro until Day 7 (day of IVF = Day 0). For transfection, the zona pellucida was removed from in vitro-produced zygotes. Zona-free zygotes were randomly assigned to 1 of 4 groups (i) GAPDH (n = 67), (ii) scrambled (n = 66), (iii) E-cadherin (n = 69) siRNA treatments at 100 nM or (iv) nontransfected controls (n = 66). Zygotes were incubated in transfection medium with siRNA for 1 h at 39°C, cultured individually in the well-of-the-well system to Day 7. The proportion of zygotes undergoing cleavage and developing to the blastocyst stage was recorded, and Day 7 embryos were frozen individually for mRNA analysis. Data for mRNA expression were fitted to a general linear model, and developmental stages were tested using ANOVA. Microinjection of 100 μM E-cadherin siRNA had no effect on phenotype (P > 0.05). Injection of PBS or 375 μM E-cadherin siRNA resulted in a decrease in the number of embryos reaching the 8-cell stage (51.5%, 45.5%, and 62.9%, respectively) and blastocyst stage (39.0%, 32.5%, and 45%, respectively) compared with noninjected controls (P < 0.05). The mRNA abundance of the target gene was suppressed by 36 and 46% when siRNA targeting E-cadherin was injected at 100 μM and 375 μM compared with control and PBS-injected groups (P < 0.05). Transfection with E-cadherin siRNA decreased development of 8-cell embryos (20.3 v. 53.0%, respectively) and blastocysts (7.2 v. 18.2%, respectively) compared with controls (P < 0.05). The mRNA relative abundance was not different between controls (nontransfected, or transfected with GAPDH or scrambled siRNA). However, transfection of zygotes with 100nM E-cadherin siRNA led to a 70% reduction in E-cadherin mRNA relative abundance in Day 7 blastocysts compared with controls (P < 0.05). Zona removal and transfection resulted in decreased embryo development compared with microinjection (P < 0.05). However, transfection yielded more efficient gene silencing of E-cadherin mRNA with reduced embryo development compared with microinjection. This technique of gene silencing could improve the efficiency of gene function studies in early bovine embryogenesis. Supported by Science Foundation Ireland.

Open-pulled straw (OPS) vitrification of in vitro fertilised mouse embryos at various stages

2008 ◽  
Vol 56 (2) ◽  
pp. 245-253 ◽  
Author(s):  
Chang-Liang Yan ◽  
Qi-En Yang ◽  
Guang-Bin Zhou ◽  
Yun-Peng Hou ◽  
Xue-Ming Zhao ◽  
...  
Keyword(s):  
Survival Rate ◽  
Developmental Stages ◽  
Developmental Rate ◽  
Blastocyst Stage ◽  
Significant Loss ◽  
Mouse Embryos ◽  
Cell Stage ◽  
Fresh Embryos

The present study was designed to investigate the cryotolerance of in vitro fertilised (IVF) mouse embryos at various preimplantation developmental stages. IVF mouse embryos were vitrified by the open-pulled straw (OPS) method. After warming, embryos were morphologically evaluated and assessed by their development to blastocysts, hatched blastocysts or term. The results showed that a high proportion (93.3–100.0%) of vitrified embryos at all developmental stages were morphologically normal after recovery. The developmental rate of vitrified 1-cell embryos to blastocyst (40.0%) or hatched blastocyst (32.7%) or term (9.3%) was significantly lower than that from other stages (P < 0.05). Vitrified embryos from 2-cell to early blastocyst stage showed similar blastocyst (71.8–89.5%) and hatched blastocyst rates (61.1–69.6%) and could develop to term without a significant loss of survival compared with those of fresh embryos (P > 0.05). Vitrified 2-cell embryos showed the highest survival rate in vivo (50.6%, 88/174), compared with that from other stages (9.3–30.5%, P < 0.05). The data demonstrate that the OPS method is suitable for the cryopreservation of IVF mouse embryos from 2-cell stage to early blastocyst stage without a significant loss of survival. Embryos at the 2-cell stage had the best tolerance for cryopreservation in the present study.

scholarly journals Effect of Increased Urea Levels on Mouse Preimplantation Embryos Developed in Vivo and in Vitro

2012 ◽  
Vol 56 (2) ◽  
pp. 211-216 ◽  
Author(s):  
Ján Bystriansky ◽  
Ján Burkuš ◽  
Štefan Juhás ◽  
Dušan Fabian ◽  
Juraj Koppel
Keyword(s):  
Apoptotic Cell ◽  
Nitrogen Concentration ◽  
High Plasma ◽  
Blastocyst Stage ◽  
Preimplantation Embryos ◽  
Cell Stage ◽  
Plasma Urea ◽  
High Concentrations

Abstract High plasma urea nitrogen concentration has been proposed as an important factor contributing to the decline in reproductive parameters of domestic animals. The aim of this study was to evaluate the effect of urea on the development of preimplantation embryos in a mouse model. During in vivo tests, acute renal failure (ARF) accompanied by hyper-uraemia was induced by intramuscular administration of glycerol (50%) into hind limbs of fertilised dams. During in vitro tests, embryos collected from healthy dams were cultured in a medium with the addition of various concentrations of urea from the 4-cell stage to the blastocyst stage. Stereomicroscopic evaluation and fluorescence staining of embryos obtained from dams with ARF showed that high blood urea is connected with an increase in the number blastocysts containing at least one apoptotic cell and in the incidences of dead cells per blastocyst, but it did not affect their ability to reach the blastocyst stage. In vitro tests showed that culture of embryos with urea at concentration of 10 mM negatively affected the quality of obtained blastocysts. Blastocysts showed significantly lower numbers of cells and increased incidence of dead cells. An increase in apoptosis incidence was observed even in blastocysts obtained from cultures with 5 mM urea. Urea at concentrations 50 mM and higher negatively affected the ability of embryos to reach the blastocyst stage and the highest used concentrations (from 500 mM) caused overall developmental arrest of embryos at the 4- or 5- cell stage. These results show that elevated levels of urea may cause changes in the microenvironment of developing preimplantation embryos, which can negatively affect their quality. Embryo growth remains un-affected up to very high concentrations of urea.

scholarly journals 243TEMPORAL DIVERGENCE IN THE PATTERN OF MRNA EXPRESSION IN BOVINE EMBRYOS CULTURED FROM THE ZYGOTE TO BLASTOCYST STAGE IN VITRO OR IN VIVO

2004 ◽  
Vol 16 (2) ◽  
pp. 242
Author(s):  
P. Lonergan ◽  
D. Rizos ◽  
A. Gutierrez-Adan ◽  
P.M. Moreira ◽  
B. Pintado ◽  
...  
Keyword(s):  
Growth Factor ◽  
Relative Abundance ◽  
Transcript Abundance ◽  
Blastocyst Stage ◽  
Insulin Like Growth Factor ◽  
Bovine Embryos ◽  
Interferon Tau ◽  
Cell Stage

The objective of this study was to examine the time during the post-fertilization culture period that gene expression patterns of in vitro cultured bovine embryos diverge from those of their in vivo cultured counterparts. Presumptive bovine zygotes were produced by IVM/IVF of immature oocytes collected from the ovaries of slaughtered animals. At approximately 20h post-insemination (hpi), presumptive zygotes were randomly divided into two culture groups, either in vitro in synthetic oviduct fluid or in vivo, and transferred into the ewe oviduct. Embryos were recovered from both systems at approximately 30hpi (2-cell), two (4-cell), three (8-cell), four (16-cell), five (early morula), six (compact morula) or seven (blastocyst) days pi and snap-frozen for the analysis of transcript abundance using real-time PCR. The transcripts studied were interferon-tau, apoptosis regulator box-a (Bax), connexin 43, sarcosine oxidase, glucose transporter 5, mitochondrial Mn-superoxide dismutase, insulin-like growth factor II, and insulin-like growth factor-I receptor, most of which are known from our previous work to be differentially transcribed in blastocysts derived from culture in vitro or in vivo. Analysis was done on pools of 10 embryos. Data were analyzed using one-way repeated measures ANOVA. The relative abundance of the transcripts studied varied throughout the preimplantation period and was strongly influenced by the culture environment. For example, transcripts for interferon-tau were detected from the 8-cell stage onwards in in vitro-cultured embryos but not until the early morula stage in those cultured in vivo. Levels of this transcript increased significantly at the compact morula and blastocyst stages in both groups but were significantly higher (P&lt;0.05) in in vitro-cultured embryos at both stages. mRNA for Bax was not detected before the 8-cell stage in in vitro cultured embryos and not until the 16-cell stage in in vivo cultured embryos. The abundance of this transcript increased significantly thereafter up to the blastocyst stage in both groups. The level of expression was significantly higher (P&lt;0.05) at all stages of development in in vitro-cultured embryos than those cultured in vivo. The relative abundance of Cx43 transcripts decreased in both in vitro- and in vivo-cultured embryos at the 8- to 16-cell stage. Levels remained low thereafter in the in vitro-cultured embryos but significantly increased in those cultured in vivo. Transcript abundance was significantly higher in in vivo cultured embryos from Day 4 onwards with a ten-fold difference presence at the blastocyst stage. Differences also existed for the other transcripts studied. These data demonstrate that changes in transcript abundance in blastocyst stage embryos are in many cases a consequence of perturbed transcription earlier in development. Depending on the transcript, these differences may be evident in as short as 10h of culture.

Phosphorylated H2AX in parthenogenetically activated, in vitro fertilized and cloned bovine embryos

Zygote ◽  
2014 ◽  
Vol 23 (4) ◽  
pp. 485-493 ◽  
Author(s):  
A.F. Pereira ◽  
L.M. Melo ◽  
V.J.F. Freitas ◽  
D.F. Salamone
Keyword(s):  
Dna Damage ◽  
Developmental Stages ◽  
Blastocyst Stage ◽  
Preimplantation Embryos ◽  
Bovine Embryos ◽  
Dna Breaks ◽  
Embryo Production ◽  
Cell Stage ◽  
Γh2ax Foci

SummaryIn vitro embryo production methods induce DNA damage in the embryos. In response to these injuries, histone H2AX is phosphorylated (γH2AX) and forms foci at the sites of DNA breaks to recruit repair proteins. In this work, we quantified the DNA damage in bovine embryos undergoing parthenogenetic activation (PA), in vitro fertilization (IVF) or somatic cell nuclear transfer (SCNT) by measuring γH2AX accumulation at different developmental stages: 1-cell, 2-cell and blastocyst. At the 1-cell stage, IVF embryos exhibited a greater number of γH2AX foci (606.1 ± 103.2) and greater area of γH2AX staining (12923.6 ± 3214.1) than did PA and SCNT embryos. No differences at the 2-cell stage were observed among embryo types. Although PA, IVF and SCNT were associated with different blastocyst formation rates (31.1%, 19.7% and 8.3%, P < 0.05), no differences in the number of γH2AX foci or area were detected among the treatments. γH2AX is detected in bovine preimplantation embryos produced by PA, IVF and SCNT; the amount of DNA damage was comparable among those embryos developing to the blastocyst stage among different methods for in vitro embryo production. While IVF resulted in increased damage at the 1-cell embryo stage, no difference was observed between PA and SCNT embryos at any developmental stage. The decrease in the number of double-stranded breaks at the blastocyst stage seems to indicate that DNA repair mechanisms are functional during embryo development.

The development and expression of pluripotency genes in embryos derived from nuclear transfer and in vitro fertilization

Zygote ◽  
2013 ◽  
Vol 22 (4) ◽  
pp. 540-548 ◽  
Author(s):  
Li-Bing Ma ◽  
Xiao-Ying He ◽  
Feng-Mei Wang ◽  
Jun-Wei Cao ◽  
Teng Cheng
Keyword(s):  
Nuclear Transfer ◽  
Developmental Stages ◽  
Es Cells ◽  
Embryonic Stem ◽  
Developmental Rate ◽  
Blastocyst Stage ◽  
Cell Stage ◽  
Vitro Fertilization ◽  
Pluripotency Genes

SummarySomatic cell nuclear transfer can be used to produce embryonic stem (ES) cells, cloned animals, and can even increase the population size of endangered animals. However, the application of this technique is limited by the low developmental rate of cloned embryos, a situation that may result from abnormal expression of some zygotic genes. In this study, sheep–sheep intra-species cloned embryos, goat–sheep inter-species cloned embryos, or sheep in vitro fertilized embryos were constructed and cultured in vitro and the developmental ability and expression of three pluripotency genes, SSEA-1, Nanog and Oct4, were examined. The results showed firstly that the developmental ability of in vitro fertilized embryos was significantly higher than that of cloned embryos. In addition, the percentage of intra-species cloned embryos that developed to morula or blastocyst stages was also significantly higher than that of the inter-species cloned embryos. Secondly, all three types of embryos expressed SSEA-1 at the 8-cell and morula stages. At the 8-cell stage, a higher percentage of in vitro fertilized embryos expressed SSEA-1 than occurred for cloned embryos. However, at the morula stage, all detected embryos could express SSEA-1. Thirdly, the three types of embryos expressed Oct4 mRNA at the morula and blastocyst stages, and embryos at the blastocyst stage expressed Nanog mRNA. The rate of expression of Oct4 and Nanog mRNA at these developmental stages was higher in in vitro fertilized embryos than in cloned embryos. These results indicated that, during early development, the failure to reactivate some pluripotency genes maybe is a reason for the low cloning efficiency found with cloned embryos.

scholarly journals 252A COMPARATIVE EXPRESSION ANALYSIS OF GENES IN PREIMPLANTATION DEVELOPMENTAL STAGES OF BOVINE EMBRYOS PRODUCED IN VITRO OR IN VIVO

2004 ◽  
Vol 16 (2) ◽  
pp. 246 ◽  
Author(s):  
D. Tesfaye ◽  
K. Wimmers ◽  
M. Gilles ◽  
S. Ponsuksili ◽  
K. Schellander
Keyword(s):  
Developmental Stage ◽  
Developmental Stages ◽  
Blastocyst Stage ◽  
The Novel ◽  
Cell Stage ◽  
Novel Transcript ◽  
Stage Of Development ◽  
Significant Difference

A comparative analysis of mRNA expression patterns between embryos produced under different in vitro and in vivo culture systems allows the isolation of genes associated with embryo quality and investigation of the effect of culture environment on the embryonic gene expression. In this study, expression analysis of four known (PSCD2, TCF7L2, NADH-subunit and PAIP1) genes and one novel transcript, derived from differential display PCR, was performed in in vitro (Ponsuksili et al., 2002, Theriogenology 57, 1611–1624) or in vivo- (Moesslacher et al., 2001 Reprod. Dom. Anim. 32, 37) produced bovine 2-, 4-, 8-, 16-cell, morula and blastocyst stage embryos using real time PCR technology. Poly(A) RNA was isolated from four separate individual embryos from each developmental stage and embryo group (in vitro or in vivo) using Dynabeads mRNA kit (Dynal, Oslo, Norway). After reverse transcription, quantitative PCR was performed with sequence specific primers in an ABI PRISM® 7000 Sequence Detection System instrument (Applied Biosystems, Foster City, CA, USA) using SYBR® Green as a double-strand DNA-specific fluorescent dye. Standard curves were generated for target and endogenous genes using serial dilutions of plasmid DNA. Final quantification was done using the relative standard curve method, and results were reported as relative expression or n-fold difference to the calibrator cDNA (i.e., the blastocyst stage) after normalization with the endogenous control (Histone2a). Data were analyzed using SAS version 8.0 (SAS Institute Inc., NC, USA) software package. Analysis of variance was performed with the main effects being the developmental stage and embryo source (in vitro or in vivo) and their interactions followed by multiple pairwise comparisons using Tukey’s test. No significant difference was observed in the relative abundance of the PSCD2 gene between the two embryo groups. However, its expression was higher (20-fold) (P&lt;0.05) at the 8-cell stage than the other developmental stages among in vitro embryos. Higher expression (P&lt;0.05) of NADH-subunit mRNA was detected in vivo than in vitro at the 2-cell stage of development. The TCF7L2 mRNA was expressed in the in vitro embryos but not in the in vivo ones. PAIP1 mRNA was higher (P&lt;0.05) in in vitro (1500-fold) than in the in vivo embryos (500-fold) at the 2-cell developmental stage compared to the calibrator. The novel transcript was also detected at higher level (P&lt;0.05) in the in vitro than in the in vivo embryos at the 2-cell stage of development. However, the PAIP1 and the novel transcript showed no significant difference in their expression between the two embryo groups beyond the 2-cell developmental stage. Both PAIP1 and the novel transcript were detected only up to 8-cell stage in both embryo groups, suggesting their maternal origin. In conclusion, the variations in the expression of studied genes between in vitro and in vivo may reflect the effect of the two culture systems on the transcriptional activity of early embryos.

Effect of embryonic cell cycle of nuclear donor embryos on the efficiency of nuclear transfer in Japanese black cattle

Zygote ◽  
2007 ◽  
Vol 15 (2) ◽  
pp. 165-171
Author(s):  
M. Kishi ◽  
R. Takakura ◽  
Y. Nagao ◽  
K. Saeki ◽  
Y. Takahashi
Keyword(s):  
Cell Cycle ◽  
Nuclear Transfer ◽  
Blastocyst Stage ◽  
Embryonic Cell ◽  
Embryonic Cells ◽  
Japanese Black Cattle ◽  
Cell Stage ◽  
Cell Cycle Stage

SummaryIn the present study, the development in vitro and in vivo of nuclear transfer (NT) embryos reconstructed with embryonic cells (blastomeres) at the 32- to 63-cell (sixth cell cycle) and 64- to 127-cell (seventh cell cycle) stages was investigated to determine the optimum range of embryonic cell cycles for yielding the highest number of identical calves in Japanese black cattle. Rates of development to the blastocyst stage (overall efficiency) were higher in the sixth cell-cycle stage (45%) than in the seventh cell-cycle stage (12%). After the transfer of the blastocysts reconstructed with blastomeres of the sixth and seventh cell cycle-stage embryos to recipient heifers, there were no differences in the pregnancy (14/35: 40% versus 3/13: 23%, respectively) or calving rates (11/39: 28% versus 3/13: 23%, respectively). These results indicate that the highest number of identical calves would be obtained by using sixth cell cycle (32- to 63-cell)-stage embryos as nuclear donors.

Differential effects of culture and nuclear transfer on relative transcript levels of genes with key roles during preimplantation

Zygote ◽  
2006 ◽  
Vol 14 (1) ◽  
pp. 81-87 ◽  
Author(s):  
P.N. Moreira ◽  
R. Fernández-Gonzalez ◽  
M.A. Ramirez ◽  
M. Pérez-Crespo ◽  
D. Rizos ◽  
...  
Keyword(s):  
Nuclear Transfer ◽  
Culture Medium ◽  
Cumulus Cell ◽  
Blastocyst Stage ◽  
Mrna Levels ◽  
Differential Effects ◽  
Glut 1 ◽  
Mouse Somatic Cell

It is well known that the preimplantation culture environment to which embryos are exposed influences the expression of developmentally important genes. Recently, it has been reported that MEMα, a culture medium commonly used for somatic cells, allows high rates of preimplantation development and development to term of mouse somatic cell nuclear transfer (SCNT) embryos. The objective of this study was to compare the differential effects of this medium and of the nuclear transfer procedure on the relative mRNA abundance of several genes with key roles during preimplantation. The relative mRNA levels of nine genes (Glut 1, Glut 5, G6PDH, Bax, Survivin, Gpx 1, Oct4, mTert and IGF2bp1) were quantified at blastocyst stage on cumulus cell cloned embryos cultured in MEMα, as well as on in vivo cultured and MEMα cultured controls. Only three of the nine transcripts analysed (Glut 5, Gpx 1 and Igf2bp1) were significantly down-regulated at blastocyst stage in in vitro produced controls. However, most genes analysed in our MEMα cultured cloned embryos showed altered transcription levels. Interestingly, between cloned and in vitro produced controls only the transcription levels measured for Glut 1 were significantly different. This result suggests that Glut 1 may be a good marker for embryo quality after cumulus cell nuclear transfer.

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