263 GENE EXPRESSION PROFILING OF IMMATURE AND IN VITRO-MATURED BOVINE OOCYTES USING AFFYMETRIX GENECHIP TECHNOLOGY

2007 ◽  
Vol 19 (1) ◽  
pp. 248 ◽  
Author(s):  
F. Carter ◽  
T. Fair ◽  
S. Park ◽  
M. Wade ◽  
A. C. O. Evans ◽  
...  

Previous studies by our group have demonstrated that oocyte maturation is a crucial event in the determination of subsequent developmental competence. The objective of the current study was to characterize changes in gene expression profiles of bovine oocytes during meiotic maturation. To this end, 5 replicate pools of 200 bovine cumulus–oocyte complexes (COCs)were collected from the ovaries of slaughtered heifers. Upon recovery, 100 COCs from each replicatewere immediately denuded, and the oocytes were snap frozen in liquid nitrogen. The remaining 100 COCs were matured in vitro in TCM-199 supplemented with 10% (v/v) fetal calf serum and 10 ngmL-1 epidermal growth factor for 24 h at 39�C under an atmosphere of 5% CO2 in air with maximum humidity. Following maturation, the remaining COCs were denuded and snap frozen. Total RNA was isolated (mean total RNA content 106.08�38.87 ng per 100 oocytes) and subjected to 2 rounds of amplification incorporating biotin-labeled nucleotides during the second in vitro transcription reaction (mean total RNA content 155.15�51.14 �g per 100 oocytes post-amplification). The resulting labeled antisense RNA was hybridized to a GeneChip Bovine Genome Arrays (Affymetrix, Inc., Santa Clara, CA, USA) (10 chips, 5 replicates each of immature and mature oocytes, n=100 oocytes/chip). Expression data were analysed using Genespring software (Agilent Technologies, Palo Alto, CA, USA), and data were normalized to the median. Overall, 54.9�1.3% and 53.3�3.3% of the 24 178 probe sets representing 23 000 transcripts spotted on the arrays were expressed in immature and in vitro-matured oocytes, respectively. Across the 5 array comparisons, 52 genes were consistently exclusively present in immature oocytes, whereas 16 genes were exclusively present in mature oocytes. A further 821 genes were found to be differentially expressed (≥2-fold) between the 2 groups (P <0.05), of which 209 were up-regulated and 612 were down-regulated in the in vitro-matured oocytes compared with their immature counterparts. The differentially expressed transcripts were classified according to their gene ontology (http://benzer.ubic.ca/ermineJ). The existing Affymetrix annotation was updated by blasting the sequences against bovine, human, and murine databases (≥90% homology; increasing molecular function annotation from 14% to 42%). In terms of olecular function, the majority of these genes were associated with protein or nucleic acid binding (>42%), catalytic activity (24%), signal transduction (7%), transporter activity (5%), and structural molecule activity (5%). In conclusion, we have stablished the molecular transcriptome blueprint of immature and in vitro-matured bovine oocytes. Through comparisons with in vivo-matured oocytes, this resource will be invaluable in determining genes that are involved in controlling the developmental competence of oocytes. This research was funded by the Science Foundation Ireland (02/IN1/B78).

2010 ◽  
Vol 22 (1) ◽  
pp. 297
Author(s):  
L. Jiang ◽  
S. L. Marjani ◽  
M. Bertolini ◽  
H. A. Lewin ◽  
G. B. Anderson ◽  
...  

During the past several decades, in vitro fertilization (IVF) has been increasingly used in animal production and human infertility treatment. In vitro production (IVP) has been shown to cause reduced developmental competence, aberrant gene expression, and developmental abnormalities. Our objective was to determine how in vitro procedures influence global gene expression during fetal development. To this end, we analyzed the gene expression profiles of liver and placentome tissue samples (n = 18) from IVP and in vivo-derived fetuses at Days 90 and 180 of gestation (n = 5 IVP and n = 4 in vivo-derived pregnancies for each day of gestation). Standard in vitro maturation and fertilization protocols were employed. Putative zygotes were co-cultured with bovine oviductal epithelial cells to the blastocyst stage. In vivo embryos were collected 7 days after AI by nonsurgical uterine flushing. Blastocyst-stage IVP and in vivo embryos were transferred to synchronized recipients and monitored until collection at Day 90 or 180. The pregnancy rate at Day 90 was 12% and 27% for IVP and in vivo pregnancies, respectively (Bertolini et al. 2004 Reproduction 128, 341-354). To conduct expression profiling, total RNA from each tissue sample and a standard reference was indirectly labeled with Cy3 and Cy5, respectively, and hybridized in duplicate to custom, bovine 13 K oligonucleotide microarrays. After Loess normalization, a two-way (origin and day) ANOVA model (GeneSpring 7.3.1) was used to identify differentially expressed genes in each tissue. The P-values were adjusted for multiple comparisons using a 5% false discovery rate (FDR). The expression of 11 candidate genes was confirmed independently by quantitative RT-PCR. Surprisingly, in both the liver and placentome tissues, no differential gene expression was detected between the IVP and in vivo fetuses at Day 90 and 180. This was observed even when the FDR was relaxed to 10% and 20%. A total of 879 genes (523 genes ≥ 1.5-fold) were differentially expressed during liver development from 90 to 180 days of gestation. Conversely, no differential gene expression was detected in the placentomes during this developmental period. Our findings show that during early and mid gestation, surviving IVP fetuses had normal patterns of gene expression. It is possible that embryos with less severe perturbations may survive with their gene expression normalized as development proceeds. Additionally, initial changes in gene expression caused by IVP may affect subsequent development, but do not necessarily persist throughout gestation. Present addresses: L. Jiang, Columbia University, New York, NY, USA; S. L. Marjani, Yale University, New Haven, CT, USA; M. Bertolini, University of Fortaleza, CE, Brazil. This work was supported by USDA grants to X.Y, H.A.L., and X.C T.


Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1794
Author(s):  
Konstantina Stamperna ◽  
Themistoklis Giannoulis ◽  
Eleni Dovolou ◽  
Maria Kalemkeridou ◽  
Ioannis Nanas ◽  
...  

Heat shock protein 70 (HSP70) is a chaperon that stabilizes unfolded or partially folded proteins, preventing inappropriate inter- and intramolecular interactions. Here, we examined the developmental competence of in vitro matured oocytes exposed to heat stress with or without HSP70. Bovine oocytes were matured for 24 h at 39 °C without (group C39) or with HSP70 (group H39) and at 41 °C for the first 6 h, followed by 16 h at 39 °C with (group H41) or without HSP70 (group C41). After insemination, zygotes were cultured for 9 days at 39 °C. Cleavage and embryo yield were assessed 48 h post insemination and on days 7, 8, 9, respectively. Gene expression was assessed by RT-PCR in oocytes, cumulus cells and blastocysts. In C41, blastocysts formation rate was lower than in C39 and on day 9 it was lower than in H41. In oocytes, HSP70 enhanced the expression of three HSP genes regardless of incubation temperature. HSP70 at 39 °C led to tight coordination of gene expression in oocytes and blastocysts, but not in cumulus cells. Our results imply that HSP70, by preventing apoptosis, supporting signal transduction, and increasing antioxidant protection of the embryo, protects heat stressed maturing bovine oocyte and restores its developmental competence.


2005 ◽  
Vol 17 (8) ◽  
pp. 751 ◽  
Author(s):  
Mona E. Pedersen ◽  
Øzen Banu Øzdas ◽  
Wenche Farstad ◽  
Aage Tverdal ◽  
Ingrid Olsaker

In this study the synthetic oviduct fluid (SOF) system with bovine oviduct epithelial cell (BOEC) co-culture is compared with an SOF system with common protein supplements. One thousand six hundred bovine embryos were cultured in SOF media supplemented with BOEC, fetal calf serum (FCS) and bovine serum albumin (BSA). Eight different culture groups were assigned according to the different supplementation factors. Developmental competence and the expression levels of five genes, namely glucose transporter-1 (Glut-1), heat shock protein 70 (HSP), connexin43 (Cx43), β-actin (ACTB) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), analysed as mRNA by using reverse transcription–polymerase chain reaction, were measured on bovine embryos cultured for 9 days. Gene expression of these in vitro-produced embryos was compared with the gene expression of in vivo-produced embryos. There was no significant difference found in embryo developmental competence between the Day 9 embryos in BOEC co-culture, FCS and BSA supplements in SOF media. However, differences in gene expression were observed. With respect to gene expression in in vivo and in vitro embryos, BOEC co-culture affected the same genes as did supplementation with FCS and BSA. HSP was the only gene that differed significantly between in vitro and in vivo embryos. When the different in vitro groups were compared, a significant difference between the BOEC co-culture and the FCS supplementation groups due to Glut-1 expression was observed.


2006 ◽  
Vol 18 (2) ◽  
pp. 120
Author(s):  
Z. Beyhan ◽  
P. Ross ◽  
A. Iager ◽  
A. Kocabas ◽  
K. Cunniff ◽  
...  

Identification of genes implicated in the biological processes of somatic cell nuclear transfer will improve our understanding of reprogramming events, i.e. the transformation of a lineage-committed cell into a pluripotent one. In addition, the gene expression profile of cloned embryos can help explain the widely reported developmental failures in cloned animals. In this study, we investigated global gene expression profiles of bovine in vitro-fertilized and cloned embryos using Gene Chip Bovine Genome Arrays (Affymetrix, Inc., Santa Clara, CA, USA). For the generation of cloned bovine blastocysts from two adult fibroblast lines (C and D), we employed methods previously proven to generate live offspring and compared these offspring to in vitro-produced blastocysts. Total RNA isolated from groups of 10 blastocysts was amplified by a template-switching PCR. Amplified cDNAs were used to synthesize biotin-labeled antisense RNAs (aRNAs) during and in vitro transcription reaction. Labeled aRNAs were hybridized to microarrays as described by the manufacturer. Experiments were performed in four replicates. Expression data were analyzed using the Significance Analysis of Microarrays (SAM; Tusher et al. 2001 Proc. Natl. Acad. Sci. 98, 5116-5121) procedure and software. Overall, 48.4% and 46% of 23 000 bovine transcripts spotted on the arrays were present in cloned and in in vitro-produced control blastocysts, respectively. The SAM procedure identified 43 genes that changed at least 1.5-fold, with an estimated false discovery rate (FDR) of 20%. Comparison of gene expression between NT embryos produced from two different cell lines and IVF controls with the same criteria revealed 6 (clones from cell line C vs. IVF) and 46 (clones from cell line D vs. IVF) differentially expressed genes. The number of transcripts expressed differentially between the cloned embryos with different donor cell origin was 437. Of the 43 differentially expressed transcripts in cloned blastocysts, 13 have unknown functions and the rest of the genes related to cell structure (tuftelin, desmoplakin), cell cycle/mitosis (Kinesin like 4, katanin, stathmin, PCNA), energy metabolism (lactate dehydrogenase, ATPsynthase, lipid-binding protein, keto acid dehydrogenase E1, metallothionein), and cell signaling (GTP-binding protein1, GTP binding stimulatory protein). Our results indicate that expression profiles of cloned blastocysts could be affected by somatic donor cell.


2008 ◽  
Vol 20 (1) ◽  
pp. 165
Author(s):  
X. S. Cui ◽  
X. Y. Li ◽  
T. Kim ◽  
N.-H. Kim

Trichostatin A (TSA) is an inhibitor of histone deacetylase and is able to alter gene expression patterns by interfering with the removal of acetyl groups from histones. The aim of this study was to determine the effect of TSA treatment on the development and gene expression patterns of mouse zygotes developing in vitro. The addition of 100 nm TSA to the culture medium did not affect the cleavage of mouse embryos (TSA treatment, 148/150 (99%) v. control, 107/107 (100%)); however, embryos that were treated with TSA arrested at the 2-cell stage (145/148, 98%). We estimated the number of nuclei in control and TSA-treated embryos by propidium iodide staining, taking into account the presence of any cells with two or more nuclei. At 62–63 h post-hCG stimulation, control zygotes had developed to the 4-cell stage and exhibited one nucleus in each blastomere, indicative of normal development. In contrast, we observed tetraploid nuclei in at least one blastomere in 20.8% (11/53) of the embryos that had been treated with TSA. At 28–29 h post-hCG stimulation (metaphase of the 1-cell stage), there was no difference in the mitotic index (as determined by analyzing the microtubule configuration) in the TSA group compared to the control group. At the 2-cell stage, however, we did not observe mitotic spindles and metaphase chromatin in embryos in the TSA treatment group compared to the controls. Interestingly, when embryos were cultured in TSA-free medium from 35 h post-hCG stimulation (S- or early G2-phase of the 2-cell stage) onward, almost all of them (47/50) developed to the blastocyst stage. In contrast, when embryos were cultured in TSA-free medium from 42 h post-hCG stimulation (middle G2-phase of the 2-cell stage) onward, they did not develop to the 4-cell stage. We used Illumina microarray technology to analyze the gene expression profiles in control and TSA-treated late 2-cell-stage embryos. Applied Biosystems Expression System software was used to extract assay signals and assay signal-to-noise ratio values from the microarray images. Our data showed that 897 genes were significantly (P < 0.05; 2-sample t-test) up- or down-regulated by TSA treatment compared to controls. Analysis using the PANTHER classification system (https://panther.appliedbiosystems.com) revealed that the 575 genes that were differentially expressed in the TSA group compared to the control were classified as being associated with putative biological processes or molecular function. Overall, in terms of putative biological processes, more nucleoside, nucleotide, and nucleic acid metabolism, protein metabolism and modification, signal transduction, developmental process, and cell cycle genes were differentially expressed between the TSA and control groups. In terms of putative molecular function, more nucleic acid-binding transcription factor and transferase genes were differentially expressed between the groups. The results collectively suggest that inhibition of histone acetylation in mouse embryos affects gene expression profiles at the time of zygotic genome activation, and this subsequently affects further development.


2008 ◽  
Vol 20 (1) ◽  
pp. 82
Author(s):  
M. Paczkowski ◽  
C. Bidwell ◽  
D. Spurlock ◽  
J. Waddell ◽  
R. L. Krisher

The in vitro culture environment significantly impacts nuclear maturation, fertilization, embryonic development, and epigenetic competence; however, our knowledge of the effects of in vitro maturation on oocyte developmental competence, and specifically cytoplasmic maturation, is limited. The objective of this experiment was to identify alterations in the transcriptome of oocytes matured in vitro compared to those matured in vivo that correlate to developmental competence. Immature oocytes were collected from Day 26 and 7-8-week-old B6D2F1 mice 48 h post-pregnant mare serum gonadotropin (PMSG) administration and matured for 16 h in Gmat supplemented with 0.5 mm citric acid, 0.5 mm cysteamine, 100 ng mL–1 epidermal growth factor (EGF), 0.05% insulin-transferrin-selenium (ITS; v/v), 0.01% recombumin (v/v) and 2 mg mL–1 fetuin. In vivo-matured oocytes from females of the same ages were collected from the oviducts 62 h post-PMSG and 14 h post-hCG and mating to vasectomized males. In vivo- and in vitro-matured oocytes were identified visually by the presence of the first polar body. Mature oocytes were pooled into three groups of 150 oocytes per treatment and lysed; poly A+ RNA was extracted. Samples were processed through two cycles of linear amplification and hybridized to the GeneChip� Mouse Genome 430 2.0 Array (Affymetrix, Inc., Santa Clara, CA, USA), with three arrays per treatment. Microarray data were sorted and filtered to include genes that were classified as having two present calls per treatment. The data were then normalized to the chip median and analyzed using a one-way analysis of variance; the level of significance was calculated at P < 0.01. In total, 2.17% (482/22170) and 1.61% (358/22170) of genes were differentially expressed between in vitro- and in vivo-matured oocytes in Day 26 and 7–8-week-old mice, respectively. However, 72.82% (351/482) and 67.87% (243/358) of differentially expressed genes had increased abundance in the in vitro- and in vivo-matured oocytes, respectively. Transcripts involved in gene expression, cellular growth and proliferation, and cellular development were increased in in vivo-matured oocytes from both age groups compared to those matured in vitro. Cell death was one of the higher ranking functional groups increased in the 7–8-week-old in vitro-matured oocytes compared to the 7–8-week-old in vivo-matured oocytes. Specific genes altered by in vitro maturation conditions in Day 26 oocytes were DNA methyltransferase 1 (>7-fold increase in vivo), caspase 8 (>4-fold increase in vivo), and eukaryotic translation initiation factor 1B (>4-fold increase in vivo). DNA methyltransferase 1 and ubiquitin-conjugating enzyme E2T were significantly increased in in vivo-matured 7–8-week-old oocytes (>3-fold and >5-fold, respectively). These results indicate that gene expression is altered in oocytes matured in vitro compared to those matured in vivo. Based on the functional annotations of genes differentially expressed, dysregulation of gene expression in the oocyte resulting in altered DNA methylation and an up-regulation in cell death pathways are potential developmental mechanisms influenced by in vitro culture conditions that correlate to reduced embryonic developmental potential.


2010 ◽  
Vol 22 (1) ◽  
pp. 329
Author(s):  
C. L. V. Leal ◽  
S. Mamo ◽  
T. Fair ◽  
P. Lonergan

Once removed from the follicle, mammalian oocytes resume meiosis spontaneously and progress through breakdown of the germinal vesicle to the matured state at metaphase II. The ability to reversibly inhibit such meiotic resumption has been reported and is a potentially useful method for studying developmental competence acquisition in oocytes as well as in some cases allowing flexibility in an IVF system where oocytes are collected from distant locations or on different days. The aim of the present study was to determine the effect of temporary inhibition of meiotic resumption using the cyclin-dependent kinase inhibitor butyrolactone I (BLI) on gene expression in bovine oocytes. Immature bovine oocytes were recovered from the ovaries of slaughtered heifers at a commercial abattoir and assigned to 1 of 4 groups: (1) Control: immature oocytes were collected either immediately or (2) after IVM for 24 h in TCM-199 containing 10 ng mL-1 EGF and 10% (v/v) FCS, (3) Inhibited oocytes collected either 24 h after incubation in the presence of 100 μM BLI in TCM-199 with 3 mg mL-1 BSA or (4) after meiotic inhibition for 24 h followed by in vitro maturation. All cultures were carried out at 38.5°C under 5% CO2 in air and maximum humidity. For mRNA relative abundance analysis, cumulus cells were removed and pools of 10 denuded oocytes were snap frozen in liquid nitrogen and stored at -80°C until use. A total of 42 transcripts, previously reported to be related to cell cycle regulation and/or oocyte competence were evaluated by quantitative real time PCR. Differences in relative abundance were analyzed by ANOVA and Student’s t-test. The majority of transcripts were downregulated (P < 0.05) after IVM in control oocytes (23 out of 42) and the same pattern was observed in inhibited oocytes that were allowed to mature. Twelve transcripts remained stable (P > 0.05) after IVM in control oocytes; of these, only two (PTTG1 and INHBA) did not show the same pattern in inhibited and matured oocytes. Few genes (7) were upregulated after IVM in control oocytes (P < 0.05) and of these, three (PLAT1, RBP1, and INHBB) were not upregulated in inhibited oocytes after IVM. Inhibited oocytes showed similar levels of expression (P > 0.05) as immature control oocytes, except for two genes (LUM and INHBB), which were increased in these oocytes (P < 0.05). The expression profiles of cell cycle genes were mostly unaffected by the BLI treatment. The few genes affected were previously reported as competence-related and could be useful markers of oocyte competence following pretreatment. In conclusion, the changes occurring in transcript abundance during oocyte maturation in vitro were to a large extent mirrored following inhibition of meiotic resumption prior to IVM and subsequent release from inhibition and maturation. CLV Leal was supported by CNPq, Brazil (PDE 201487/2007-1); Supported by Science Foundation Ireland (07/SRC/B1156).


2017 ◽  
Vol 29 (1) ◽  
pp. 180
Author(s):  
T. Yamanouchi ◽  
S. Sugimura ◽  
H. Matsuda ◽  
M. Ohtake ◽  
Y. Goto ◽  
...  

Bovine oocytes obtained by ovum-pick-up (OPU) following follicle growth treatment (FGT) have improved quality and competence (Imai et al. 2008 Reprod. Fertil. Dev. 20, 182). However, the effect of the presence of FSH or epidermal growth factor (EGF) like peptide during in vitro maturation (IVM) on the developmental competence of FGT oocytes has not been well known. This study was undertaken to examine the developmental competence of FGT oocytes following IVM in the presence of FSH (recombinant human FSH) or EGF-like peptide (amphiregulin; Areg) and IVF. Japanese Black cows (n = 17) were used as donors. Five days after arbitrary OPU (opu group), follicles ≥8 mm in diameter were aspirated again, a controlled internal drug release (CIDR) was inserted into the vagina, and then pFSH was injected twice a day from the evening of Day 6 to the morning of Day 10 with decreasing doses (total of 20 AU; 4, 4, 3, 3, 2, 2, 1, 1 AU/day). On the evening of Day 8, PGF2α (0.5 mg of cloprostenol) was administered. On Day 11, oocytes were aspirated from follicles with ≥5 mm in diameter of the treated donors by OPU (fgt group). The cumulus-oocyte complexes (COC) were cultured in the absence (opu-cont and fgt-cont groups) or presence of 0.1 IU mL−1 FSH (opu-fsh and fgt-fsh groups) or 100 ng mL−1 Areg (opu-areg and fgt-areg groups) in IVM medium (mTCM199 containing 5 mg mL−1 BSA) for 20 to 22 h (1 COC/5 µL, total of 162–171 COC per group), and then co-cultured with 3 × 106 sperm/mL for 6 h. The presumptive zygotes were continued to culture in mCR1aa supplemented with 5% newborn calf serum for 216 h (1 zygote/5 µL) using micro-well culture dishes (Dai-Nippon-Print). When repeating this opu-fgt session in the same cow, an interval at least for 50 days was kept, and the session was performed 28 times. Statistical analysis was carried out by Mann-Whitney’s U-test (between opu and fgt groups) or Steel-Dwass test after Kruskal-Wallis test (among all groups). The number of follicles ≥5 mm increased in the fgt than opu group (17.8 v. 2.9; P < 0.01). The number of COC collected was not different between the opu and fgt groups (23.1 v. 19.6; P > 0.05). The blastocyst formation rate was higher in the fgt than opu group (36.9 v. 23.1%; P < 0.01). Within 6 groups, the blastocyst formation rate was higher in the fgt-fsh (43.3%; P < 0.01) and fgt-areg (39.5%; P < 0.05) groups than the opu-cont (16.3%) group. The rate in the fgt-fsh group was also higher than that in the opu-fsh group (43.3 v. 18.7%; P < 0.01). These results suggested that FGT improved the developmental competence of bovine oocytes, probably through improving the ability of the COC to react against FSH/Areg.


2018 ◽  
Vol 30 (1) ◽  
pp. 206
Author(s):  
G. Singina ◽  
I. Lebedeva ◽  
T. Taradajnic ◽  
E. Shedova ◽  
A. Lopukhov ◽  
...  

Data on effects of progesterone (P4) during in vitro maturation of bovine oocytes on their capacity for embryonic development are contradictory. Our study was aimed at characterising effects of P4 and 2 luteotropic hormones, prolactin (PRL) and LH, on bovine oocyte developmental competence during the second step of two-step maturation (from metaphase (M)I to MII). Slaughterhouse-derived cumulus-enclosed oocytes (CEO) were matured for 12 or 24 h [one-step (OS) Control] in TCM-199 containing 10% fetal calf serum (FCS), 10 μg mL−1 porcine FSH, and 10 μg mL−1 ovine LH at 38.5°C and 5% CO2. The CEO cultured for 12 h were transferred to the following culture systems: (1) TCM-199 containing 10% FCS (Control 1) or (2) a monolayer of granulosa cells (GC) precultured for 12 h in TCM-199 containing 10% FCS (Control 2); then, the oocytes were matured for next 12 h. In both systems, the medium of experimental groups was supplemented with either P4 (50 ng mL−1) or bovine PRL (25 and 50 ng mL−1) or ovine LH (5 μg mL−1). All treatments were repeated 5 to 6 times using 138 to 196 oocytes per group. Following IVM, all oocytes underwent IVF as described previously (Singina et al. 2014 Reprod. Fertil. Dev. 26, 154). Embryos were cultured in CR1aa medium until Day 5 post-insemination and then transferred to the same medium supplemented with 5% FCS and cultured to Day 7. Embryo development was evaluated at Days 2 and 7 for cleavage and blastocyst formation. Apoptosis was detected by the TUNEL method using 26 to 47 blastocysts per group (from 4 to 5 separate experiments). For each system, arcsine-transformed data were analysed by one-way ANOVA. In OS Control, the cleavage and blastocyst rates were 68.9 ± 4.4% and 22.0 ± 2.4%, respectively. Regardless of the system or medium of two-step culture, the cleavage rate did not differ from that for OS Control, varying between 57.6 and 68.4%. In the absence of GC (System 1), the blastocyst yield in the P4 group (30.4 ± 0.8%) was greater (P < 0.05) than in OS Control and Control 1 (20.2 ± 2.7%) as well as in the groups treated with LH (19.1 ± 3.0%) and 25 ng mL−1 PRL (20.1 ± 2.7%). In the presence of GC, P4 raised the yield from 16.7 ± 2.3% (Control 2) to 27.7 ± 2.4% (P < 0.05). Furthermore, in System 2, the blastocyst rate in groups treated with P4 and 50 ng mL−1 PRL (25.0 ± 2.8%) was higher (P < 0.05) than in the LH group (13.9 ± 2.6%). Meanwhile, the proportion of apoptotic nuclei (2.3-6.9%) was not associated with the system of oocyte maturation or effects of hormones studied. Our data indicate that P4 (50 ng mL−1) can enhance the developmental competence of bovine oocytes during the second step of two-step maturation regardless of the presence of granulosa cells, whereas the similar effect of PRL (50 ng mL−1) is less pronounced and depends on the granulosa-conditioned environment. This research was supported by the Russian Science Foundation (project 16-16-10069).


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