152 DIELECTROPHORETIC BEHAVIOR OF BOVINE OOCYTES AND ZYGOTES IN RELATION TO DEVELOPMENT AND TRANSCRIPTIONAL ABUNDANCE

2007 ◽  
Vol 19 (1) ◽  
pp. 193
Author(s):  
D. Salilew-Wondim ◽  
F. Rings ◽  
M. Hoelker ◽  
D. Jennen ◽  
E. Tholen ◽  
...  

Selection of developmentally competent oocytes and zygotes based on external morphology has been employed to increase in vitro embryo production. However, this method is more often influenced by personal judgments and lacks universal standards. Hence, this study was aimed at investigating the dielectrophoretic behavior of oocytes and zygotes in relation to their development and mRNA abundance. To achieve the objective, 2 experiments were conducted. In the first experiment, matured bovine oocytes (PB+) and zygotes were subjected to a dielectrophoresis (DEP) procedure designed as follows: 4 MHz AC, 450-�m electrode distance, 5 V, and 80-�s cm-1 medium conductivity. The time elapsed for each of the oocytes and zygotes to reach one of the electrodes from the center was recorded. To accomplish this, 457 PB+ oocytes were subjected to the DEP procedure and 152, 121, 90, and 94 were classified as very fast, fast, slow, and very slow, respectively. Moreover, 152 oocytes were used as controls. Similarly, a total of 940 zygotes were subjected to the DEP procedure and classified as very fast (n = 329), fast (n = 329), slow (n = 97), and very slow (n = 245). In addition, 323 zygotes were used as the control group. The oocyte DEP groups were parthenogenetically activated, and the zygote DEP groups were further in vitro-cultured in a CR1 culture medium supplemented with 10% estrous cow serum, 20 mL mL-1 �-mercaptoethanol, and 10 mL mL-1 minimal essential medium. In PB+ DEP groups, the results show that the blastocyst rate (mean � SEM) at 7 days post-parthenogenetic activation was significantly (P < 0.05) lower in the very slow moving group (7.2 � 4.9) compared to the very fast (21.8 � 3.2), fast (21.5 � 4.6), slow (23.3 � 4.5), and the control (19.7 � 3.7) groups. In zygotes, the blastocyst rate at 7 days post-insemination was significantly (P < 0.05) higher in the very fast (16.1 � 2.7) compared to the slow (9.1 � 2.7) and very slow (10.6 � 2.7) groups, but it was not significantly higher than the fast (12.2 � 2.7) and control (12.3 � 2.7) groups. To investigate whether the transcriptional level of DEP separated very fast and very slow oocytes and zygotes, mRNA expression level was analyzed using a bovine cDNA microarray from a pool of 30 zygotes and oocytes in 6 replications including the dyeswap. The data analyzed using statistical analysis for microarray revealed that 31 and 5 genes were up- and down-regulated, respectively, in very fast compared to very slow PB+ DEP groups. The up-regulated genes are known to be involved in RNA binding and protein biosynthesis (RPL2, RPL8, and RPLPO), ion binding (PTGS2 and ANXA2), and cell cycle regulation (CDC91L1, NUSAP1, and CKS1B). Similarly, 25 and 17 genes were up- and down-regulated, respectively, in the very fast compared to the very slow zygote DEP groups. Some of these genes enriching the very fast zygotes are involved in ion binding (ZNF85, ZNF519, and NANOS1), regulation of cell cycle (NASP, SMARCA5, and AURKA), and signal transduction (RALA). Therefore, from this experiment we can conclude that dielectrophoretically separated oocytes and zygotes show differences in the rate of blastocyst development accompanied by differences in transcriptional abundances.

2017 ◽  
Vol 65 (4) ◽  
pp. 546-555
Author(s):  
Tayita Suttirojpattana ◽  
Tamás Somfai ◽  
Satoko Matoba ◽  
Takashi Nagai ◽  
Rangsun Parnpai ◽  
...  

This study determined the optimum storage vessel and the effects of resveratrol for the storage of in vitro matured (IVM) bovine oocytes. After IVM, the oocytes were kept in a Hepes-buffered medium at 25 °C for 20 h in different containers including Eppendorf tubes (ET) made of polypropylene (PP) and polystyrene (PS), and tissue culture tubes (TCT) made of PP, PS, and glass. Then oocytes were subjected to IVF and subsequent in vitro embryo development was compared among the groups and to that of a control group without storage. The percentage of blastocyst development in the control group was significantly higher than in the stored groups (P < 0.05). Among oocytes stored in TCT, the percentage of blastocyst development of oocytes stored in glass TCT was significantly higher than that of oocytes stored in PP and PS TCT (P < 0.05); however, it did not differ from that of oocytes stored in ET. The quality of blastocysts did not differ among the control and stored groups. Embryo development was not affected when 0.1, 1 or 10 μM resveratrol was added to the medium during oocyte storage. In conclusion, glass tubes were optimal for oocyte storage and resveratrol did not improve the development of stored oocytes.


2006 ◽  
Vol 18 (2) ◽  
pp. 272
Author(s):  
K. Kananen-Anttila ◽  
M. Eronen ◽  
J. Matilainen ◽  
M. Kallio ◽  
J. Peippo ◽  
...  

We have studied the effect of suppressed IVM on the developmental competence of bovine oocytes, aiming at elucidating the importance of cytoplasmic maturation in fertilization and embryo development. Six replicates of abattoir-derived oocytes were randomly divided into three IVM groups. Control (n = 950): TCM-199 with glutamax-I (Gibco, Grand Island, NY, USA), 0.25 mM Na-pyruvate, 100 IU mL−1 penicillin and 100 μg mL−1 streptomycin, 50 ng mL−1 FSH, and 10% fetal bovine serum (FBS) (Gibco); Serum+FSH-free (n = 944): same as control but without FSH and FBS; α-amanitin (n = 977): same as control but with 10 μg mL−1 α-amanitin. Nuclear maturation of oocytes was studied 24 h after the onset of IVM, the formation of sperm aster structure 10 hours post-insemination (hpi) and the formation of pronuclei 20 hpi. Sperm aster was visualized with β-tubulin antibody (modified from Navara et al. 1999 Dev. Biol. 162, 29–40). Presumptive zygotes were cultured until Day 7 in modified SOFaaci + 4 mg mL−1 fatty acid-free BSA in 5% O2. Cumulus cell expansion was seen only in the control group. The results of nuclear maturation, fertilization, and embryo development are summarized in Table 1. Serum and FSH deprivation did not have a statistically significant effect on the parameters studied (vs. control). α-amanitin exposure during IVM reduced nuclear maturation, fertilization, and Day 3 embryo cleavage vs. control, and resulted in total blockage of Day 7 blastocyst development. The treatment groups had significantly smaller mean diameters of male pronuclei (control: 14 ± 0.6 μ­m; serum+FSH-free: 12 ± 0.5 μ­m, P < 0.05; α-amanitin: 10 ± 0.6 μ­m, P < 0.001) and sperm asters (control: 86 ± 4 μ­m; serum+FSH-free: 82 ± 4 μ­m, P < 0.01; α-amanitin: 49 ± 7 μm, P < 0.001) (nonparametric Kruskall Wallis and Mann-Whitney U tests) vs. control group. Despite reduction in pronucleus and sperm aster diameter, serum and FSH deprivation during IVM did not affect in vitro developmental competence of bovine oocytes, suggesting a need for re-evaluation of the components of IVM. α-Amanitin exposure in IVM disturbed nuclear maturation, fertilization, and embryo development, indicating the essence of early transcription. Table 1. Average percentages ± (n) for nuclear maturation, fertilization (min two pronuclei), embryo cleavage, and blastocyst development


2007 ◽  
Vol 19 (1) ◽  
pp. 273 ◽  
Author(s):  
A. Sugulle ◽  
S. Katakawa ◽  
S. Yamamoto ◽  
S. Oomori ◽  
I. Itou ◽  
...  

The morphological identification of immature oocytes has commonly been used to select the bovine oocytes for IVF. However, &lt;30% of the recovered oocytes reach the blastocyst stage after fertilization, and this is probably due to the quality of the oocytes at the beginning of maturation. The brilliant cresyl blue (BCB) stain determines the activity of glucose-6-phosphate dehydrogenase, an enzyme synthesized in growing oocytes. The aim of this study was to evaluate the effect of the BCB stain on the selection of bovine oocytes and on the subsequent embryo development for in vitro production (IVP). Cumulus–oocyte complexes (COCs) were collected by the aspiration of 2- to 6-mm follicles. A total of 559 oocytes were divided into 2 groups: (1) a control group, immediately cultured, and (2) a BCB-incubated group. After 90 min of BCB staining (Pujol et al. 2004 Theriogenology 61, 735–744), the oocytes were divided into oocytes with blue cytoplasm (BCB+) and oocytes without blue cytoplasm (BCB−). The COCs were matured for 20 h in TCM-199 supplemented with 5% calf serum (CS) and 0.02 mg mL−1 FSH at 38.5°C under an atmosphere of 5% CO2 in air. The matured COCs were inseminated with 5 × 106 sperm mL−1. After 18 h of gamete co-culture, the presumed zygotes were cultured in CR1aa supplemented with 5% CS for 9 days at 38.5°C under an atmosphere of 5% CO2, 5% O2, and 90% N2. Embryonic development was evaluated at 48 h after IVF (proportion of ≥5-cell stage, the total cleavage rates) and on Days 7 to 9 (blastocyst rate). The experiment was replicated 5 times, and the data were analyzed by a chi-square test and ANOVA. The results are presented in Table 1. The proportion of embryos with ≥5-cell stage was significantly higher (P &lt; 0.01) in the BCB+ group than in the BCB− group, but not in the control group. The total cleavage rate for the BCB+ embryos was significantly higher than that of either the BCB− or the control group (P &lt; 0.01). There were also significant differences (P &lt; 0.01) in the blastocyst development between the BCB+ and BCB− embryos and between the BCB− and the control embryos (P &lt; 0.05). This result showed that the selection of bovine oocytes by BCB staining before in vitro maturation may be useful for selecting oocytes that are developmentally competent up to Day 9 for IVP. Table 1.Effect of selection of oocytes by brilliant cresyl blue (BCB) staining on the subsequent embryo development of in vitro-matured/in vitro-fertilized bovine embryos


Zygote ◽  
2009 ◽  
Vol 18 (3) ◽  
pp. 209-216 ◽  
Author(s):  
Gustavo Bruno Mota ◽  
Ribrio Ivan Tavares Pereira Batista ◽  
Raquel Varella Serapião ◽  
Mariana Cortes Boité ◽  
João Henrique Moreira Viana ◽  
...  

SummaryThe objective of this work was to evaluate the selection of immature bovine oocytes by brilliant cresyl blue dye (BCB) and expression of transcripts MATER and ZAR1. Cumulus–oocyte complexes (COCs) from slaughterhouse ovaries were exposed to BCB diluted in mDPBS and incubated for 60 min at 38.5 °C in humidified air. After exposure those COCs were distributed in two groups, according to their cytoplasm colour: BCB+ (coloured cytoplasm) or BCB− (colourless cytoplasm). The control group was submitted to in vitro maturation (IVM) immediately after morphological selection and holding control group COCs were exposed to mDPBS without BCB but in the same incubation conditions of BCB+ and BCB− group. The COCs of all groups were submitted to IVM, in vitro fertilization (IVF) and in vitro culture (IVC). Cleavage rate (72 h post-insemination) was similar between control (65.3%) and BCB+ (64.4%) groups, but greater than (p < 0.05) holding control (49.8%) and BCB− (51.3%) groups. Blastocyst rate (192 h post-insemination) was not different between BCB+ (18.5%) and control (16.3%) groups, but greater (p < 0.05) than BCB− (8.4%) group. No difference was found for blastocyst rate between holding control group (14.2%), control and BCB+ groups. The relative expression of MATER and ZAR1 genes was evaluated by real-time PCR in immature oocytes collected from the control, holding control, BCB+ and BCB− groups. Despite the relative expression of MATER in holding control, BCB+ and BCB− were down regulated in comparison to control group there was no statistical difference (p > 0.05) in the relative expression of MATER and ZAR1 transcripts among groups. The results indicate that the BCB dye detects immature oocyte populations with different developmental competence, although no improvement in in vitro embryo production using oocytes exposed or not to BCB was observed. Development competence of immature oocytes exposed to BCB does not seem to be associated with variations in the expression of MATER and ZAR1 transcripts.


Zygote ◽  
2007 ◽  
Vol 15 (4) ◽  
pp. 295-306 ◽  
Author(s):  
S.C. Méo ◽  
W. Yamazaki ◽  
C.R. Ferreira ◽  
F. Perecin ◽  
N.Z. Saraiva ◽  
...  

SummaryIn vitro-matured (IVM) bovine oocytes were activated with single and combined treatments of strontium (S), ionomycin (I) and 6-DMAP (D). Using oocytes IVM for 26 h, we observed that activation altered cell cycle kinetics (faster progression, MIII arrest, or direct transition from MII to pronuclear stage) when compared to in vitro fertilization. The effect of oocyte age on early parthenogenesis was assessed in oocytes IVM for 22, 26 and 30 h. Better results in pronuclear development were obtained in treatments ISD (81.7%) at 22 h; D (66.7%), IS (63.3%), ID (73.3%) and ISD (76.7%) at 26 h; and D (86.7%), IS (85.0%) and ID (78.3%) at 30 h. Higher cleavage occurred on ISD (80.0%) at 22 h; ID (83.3%) and ISD (91.7%) at 26 h; and I (86.7%), IS (90.0%), ID (85.0%) and ISD (95.0%) at 30 h. More blastocysts were achieved in ID (25.0%) and ISD (18.3%) at 22 h; and in ID at 26 h (45.0%) and 30 h (50.0%). We also observed that IS allowed higher haploid (77.4%) embryonic development, whilst ID was better for diploid (89.1%) development. It was concluded that association of S and D without I was not effective for blastocyst development; treatments using S were less influenced by oocyte age, but when S was associated with D there was a detrimental effect on aged oocytes; treatment ISD promoted higher activation and cleavage rates in young oocytes and ID protocol was the best for producing blastocysts.


2003 ◽  
Vol 8 (1) ◽  
Author(s):  
L.P. RAUBER ◽  
D.F. ALVES ◽  
F.D. MOZZAQUATRO ◽  
J.V. TESSMANN ◽  
M.L. BERNARDI ◽  
...  

A manutenção dos complexos cumulus-oócitos (CCO) em líquido folicular (LF) antes da sua maturação, além de visar a capacitação, viabiliza o transporte até o laboratório por ser de baixo custo, de fácil aquisição e o congelamento do LF permite seu armazenamento para futura utilização. Neste experimento avaliou-se o efeito do congelamento do LF obtido de folículos de 2-8mm e de folículos >8mm, sobre a taxa de produção embrionária. Oócitos foram aspirados de folículos de 2 a 8mm de ovários provenientes de abatedouro. No grupo controle (n=295) os CCO foram maturados por 24h. Nos tratamentos GF (n=297) e GC (n=282), os CCO foram mantidos por 6h a 30ºC em LF fresco ou congelado, respectivamente, de folículos >8mm. Já no tratamento PF(n=278) e PC (n=281), os CCO foram mantidos em LF fresco ou congelado, respectivamente, de folículos de 2-8mm. Posteriormente, os CCO dos tratamentos GF, GC, PF e PC foram maturados por 18h. Não houve efeito negativo do congelamento do líquido folicular e nem do tamanho dos folículos sobre as taxas de clivagem e produção embrionária em D7 e D9 (P>0,05). No entanto, o congelamento do LF de folículos de 2 a 8mm resultou em redução da taxa de eclosão e do número de células dos blastocistos. A manutenção de oócitos bovinos por 6h a 30ºC, antes da maturação, pode ser efetuada em líquido folicular de folículos >8mm, fresco ou congelado. Fresh or frozen follicular fluid in vitro bovine embryo production Abstract In addition to the capacitation, the maintenance of cumulus-oocyte complex (COC) in follicular fluid (FF) before maturation, allows the transport to the laboratory, being a practical and less expensive media. The FF can be stored after freezing to future use. Oocytes aspirated from bovine slaughterhouse ovaries, were used to evaluate the effect of maintaining the oocytes in fresh or frozen bovine FF (from 2-8mm and >8mm follicles) on the blastocyst rate. In the control group (n=259) the COC were matured for 24h. On treatments GF (n=297) and GC (n=282) the COC were held for 6h at 30°C in fresh or frozen FF from >8mm follicles, respectively. In treatments PF (n=278) and PC (n=281) the COC were held in fresh or frozen FF from 2-8mm follicles, respectively. Later, the COC from GF, GC, PF and PC were matured for 18h. The freezing process as well as the follicle size had no effect on the cleavage, D7 or D9 blastocyst rates (P>0,05). Nevertheless, the frozen FF from 2-8mm follicles resulted in a reduced hatching rate and lower ICM cells. Fresh or frozen follicular fluid of >8mm follicles could be used for a 6h transport of bovine oocytes before maturation for 18h.


2021 ◽  
Vol 99 (Supplement_1) ◽  
pp. 108-108
Author(s):  
Malavika K Adur ◽  
Yunsheng Li ◽  
Jason W Ross

Abstract MicroRNA are small non-coding RNA involved in post-transcriptional gene regulation impacting oocyte maturation and embryo development. MIR574-3p abundance decreases during oocyte in vitro maturation (IVM) and blastocyst development. The study objective was to evaluate the role of MIR574-3p during porcine oocyte maturation and early embryo development. To assess the function of MIR574-3p during these processes, denuded GV stage oocytes injected with MIR574-3p mimic (MIR574-3p-M), MIR574-3p inhibitor (MIR574-3p-I) or negative control oligo (NC) underwent IVM for 42 hours. The number of MII arrested oocytes was decreased (P = 0.06) in the MIR574-3p-M group (67.7 ± 1.4%) as compared to the NC group (76.1 ± 1.3%), whereas maturation was not affected by MIR574-3p-I (75.6 ± 1.5%) as compared to the NC group (73.1 ± 3.6%). MII arrested oocytes were parthenogenetically activated and cultured for 7 days. Neither mimic nor inhibitor affected the cleavage or blastocyst rate. Using LC-MS/MS we evaluated changes in global protein abundance in injected oocytes after 42 hours of IVM. We identified 971 proteins in MIR574-3p-M injected oocytes, of which 57 were differentially abundant as compared to the control group. In MIR574-3p-I injected oocytes, 1007 proteins were identified, of which 107 were differentially abundant as compared to the control group. Overall, MIR574-3p-M upregulated proteins critical to membrane binding mediating sperm receptors on the zona pellucida, while it downregulated intranuclear activity such as nucleotide biosynthesis, mitotic spindle assembly and orientation; whereas MIR574-3p-I induced upregulation of proteins involved in the processes between and including protein biosynthesis and metabolism, while downregulating proteins critical to ATP, RNA, DNA and protein binding. These data suggest artificially increasing MIR574-3p abundance during IVM alters the oocyte proteome and influences meiotic progression to MII. Project was supported by Agriculture and Food Research Initiative Competitive Grant no. 2017-67015-26459 from the USDA National Institute of Food and Agriculture.


2004 ◽  
Vol 16 (2) ◽  
pp. 238
Author(s):  
E. Gomez ◽  
C. Diez ◽  
E. Moran ◽  
A. Rodriguez ◽  
L.J. Royo ◽  
...  

As a transcription factor, retinoic acid (RA) can activate or silence a wide number of genes, thus inducing differentiation in cell systems and playing a role in cell cycle regulation. However, little is known of RA-dependent gene expression in the oocyte. Bovine oocytes and cumulus cells express most RA receptors, and the presence of 9-cis-RA during in vitro maturation (IVM) is beneficial to oocyte development (Duque et al., 2002 Hum. Reprod. 17, 2706–2714; Hidalgo et al., 2003 Reproduction 125, 409–416). The present work analyzes the relative abundance of various developmentally important gene transcripts in bovine oocytes during in vitro prematuration and/or maturation. Cumulus-oocyte complexes (COCs) were manipulated in defined medium with polyvinyl-alcohol (DM-PVA). Those COCs undergoing prematuration were cultured for 24h in DM-PVA with 25μM roscovitine. For IVM, some prematured COCs were cultured for 24h in DM-PVA containing pFSH, LH and E2. Incubations were made at 39°C in an atmosphere of 5% CO2 in air and high humidity. Within experiments, COCs were cultured with nM 9-cis-RA 5, in 1% ethanol (both as vehicle and inhibitor of endogenous RA synthesis), 3% ethanol, 5% ethanol and untreated. Using Real Time PCR (10 oocytes per group) (Rizos et al., 2003 Biol. Reprod. 68, 236) we examined the relative mRNA expression of genes involved in protection against free oxygen radicals (Mn-superoxide dismutase, MnSOD), glucose metabolism (glucose-6-phosphate dehydrogenase, G6PDH) and cell cycle events (Cyclin B1 and H1). Data (of 4 replicates) were analyzed by ANOVA and Duncan test (P&lt;0.05). Regarding immature oocytes, prematuration in 1% ethanol increased cyclin B1 expression and decreased cyclin H1, while 9-cis-RA increased G6PDH. Maturation without additives increased cyclin B1 and G6PDH, but decreased cyclin H1 and MnSOD expression;; opposite trends were observed under increasing ethanol dosages (3% and 5%). Maturation with 1% ethanol or 9-cis-RA enhanced cyclin B1 and G6PDH, while reducing cyclin H1 and MnSOD expressions. The presence of 9-cis-RA during both prematuration and maturation processes tended to show more prominent effects than the ones observed when it was present only during prematuration or maturation alone. In our study, in presence of 9-cis-RA during both prematuration and maturation processes, the expression of cyclin B1 and G6PDH tended to increase, while cyclin H1 and MnSOD tended to decrease. However, the differences with the control group without additives were not significant. Our study during both prematuration and maturation processes show that beneficial effects of RA on oocyte developmental competence may not be related to the alteration of mRNA expression of the four genes analyzed. Grant support: Spanish Ministry of Science and Technology (AGL-2002-01175; 2003-05783).


Reproduction ◽  
2006 ◽  
Vol 132 (4) ◽  
pp. 549-557 ◽  
Author(s):  
S Ikeda ◽  
K Saeki ◽  
H Imai ◽  
M Yamada

We previously reported that when midkine (MK), a heparin-binding growth differentiation factor was used inin vitromaturation (IVM) culture of bovine cumulus-enclosed oocytes (CEOs), their developmental competence to the blastocyst stage afterin vitrofertilization (IVF) was enhanced and the effect of MK might be mediated by its action upon mural granulosa cells and cumulus cells that closely surround the oocyte. In the present study, when denuded oocytes (DOs) were matured in IVM medium with or without MK (200 ng/ml) in the presence or absence of isolated cumulus cell masses and subjected to IVF, the enhancing effects of MK on the developmental competence of DOs to the blastocyst stage after IVF were exerted only in the presence of cumulus cells. In addition, we prepared the conditioned media of granulosa cells cultured with or without 200 ng MK/ml (CMMK+ or CMMK− respectively) and examined their effects on the IVM of DOs in terms of their developmental competence to the blastocyst stage after IVF. The supplementation of CMMK+ into IVM medium at 40% (v/v) significantly enhanced the blastocyst development compared with the no additive control and the CMMK− supplemented groups. Furthermore, the effects of MK during IVM of bovine CEOs on the cumulus cell apoptosis were investigated. CEOs were cultured up to 24 h in IVM medium without (control) or with 200 ng MK/ml. The genomic DNA was extracted from CEOs at 0, 6, 12, 18 and 24 h of IVM and subjected to ligation-mediated PCR (LM-PCR) to detect the apoptotic internucleosomal DNA fragmentation. DNA fragmentation was scarcely detected at the start of IVM, whereas it increased time-dependently as the IVM culture progressed. The degree of the fragmentation was significantly lower in the MK-treatment group compared with the control group at 18 and 24 h of IVM. The apoptosis-suppressing effect of MK on cumulus cells was further confirmedin situby using TUNEL on CEOs. In conclusion, data from the present study further confirmed that MK enhances the developmental competence of bovine oocytes via cumulus and granulosa cells. It was also demonstrated that MK suppresses the apoptosis that occurs in cumulus cells during the period of IVM of bovine CEOs. The putative soluble factor(s) from cumulus cells was suggested from the experiment using CMMK+ . MK may promote the production of such factors in part by its anti-apoptotic effects on cumulus cells.


2004 ◽  
Vol 16 (8) ◽  
pp. 781 ◽  
Author(s):  
Jun Xue ◽  
Melissa A. Cooney ◽  
Vanessa J. Hall ◽  
Natasha A. Korfiatis ◽  
R. Tayfur Tecirlioglu ◽  
...  

Adenosine triphosphate (ATP) plays an important role during fertilisation of the mammalian oocyte through its ability to alter the frequency and duration of calcium oscillations. It has also been shown that higher ATP levels correlate with increased developmental competence in bovine and human oocytes. During somatic cell nuclear transfer (NT), the incoming nucleus is remodelled extensively, undoubtedly using a variety of ATP-dependent enzymes. The aim of the present study was to determine whether additional exogenous ATP influences activation of parthenogenetic (PA), in vitro-fertilised (IVF) or cloned (NT) in vitro-matured bovine oocytes. Blastocyst development and cell numbers in PA embryos were found to increase in a dose-dependent manner following the photorelease of 0, 50, 100, 500 and 1000 μm DMNPE-caged ATP (adenosine 5′-triphosphate, P3-(1-(4,5-dimethoxy-2-nitrophenyl)ethyl) ester, disodium salt). No cleavage was found following release of 2 and 5 mm DMNPE-caged ATP or with DMNPE-caged ATP (not photoreleased). There were also no differences in blastocyst rates or cell numbers between the control group and groups treated with caged, but not photoreleased, ATP. The addition of exogenous ATP before IVF or to NT couplets did not result in a significant increase in blastocyst development or cell number. Embryo transfer is necessary to determine whether exogenous ATP can positively affect reprogramming, resulting in higher cloned pregnancy rates or live-term births.


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