235RETINOID-DEPENDENT MRNA EXPRESSION IN BOVINE OOCYTES
PREMATURED AND/OR MATURED IN VITRO

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<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).

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6 TIMING OF DEADENYLATION OF GDF-9 AND CYCLIN 3′ UTR CONSTRUCTS IN BOVINE OOCYTES

Reproduction Fertility and Development ◽

10.1071/rdv19n1ab6 ◽

2007 ◽

Vol 19 (1) ◽

pp. 121

Author(s):

D. J. Walker ◽

C. J. Wilusz ◽

G. E. Seidel Jr

Keyword(s):

In Vitro Maturation ◽

Control Point ◽

Tail Length ◽

Cumulus Cells ◽

Cyclin B1 ◽

Defined Medium ◽

Untranslated Regions ◽

Labeled Rna ◽

Bovine Oocytes

The maternal pool of mRNA undergoes major changes during oocyte maturation and early embryonic development. Specific genes are activated or degraded in response to changes in poly-(A) tail length. However, little is known about how the oocyte targets specific transcripts for degradation or translation in a timely manner. The objective of this study was to determine how poly-(A) tail length of different transcripts is affected in bovine oocytes by time of in vitro maturation. Cyclin B1 and GDF-9 32 untranslated regions (UTRs) were cloned into modified p-GEM plasmids containing a poly-(A) tract of 60 or 0 adenosines (A60 or A0, respectively). Each 32 UTR was transcribed in vitro with (A60) or without (A0) a poly-(A) tail to generate UTP32-labeled RNA. Transcriptions producing at least 200 000 counts per min (cpm) per �L were used for subsequent injections into denuded bovine oocytes. Cumulus-oocyte complexes (COCs) recovered from slaughterhouse-derived ovaries (n = 216) were vortexed to remove cumulus cells immediately after aspiration, after 3 h of in vitro maturation, or after 19 h of maturation in a chemically defined medium supplemented with FSH, LH, EGF, and cysteamine. After vortexing, denuded oocytes were injected and snap frozen, or matured in vitro for 1 or 3 h. Eight oocytes were injected with ~0.5 nL (~100 cpm/oocyte) labeled RNA at each time point in 3 replicates. Total RNA was isolated from injected oocyte pools and loaded onto a 5% denaturing acrylamide gel for size separation. Radiolabeled A0 was used as a control point of reference for deadenylation. Gels were dried, and RNA was visualized on a phosphoimager after 24 h exposure to a phosphor screen. Changes in polyadenylation status (transcript size) were evaluated by comparing shifts in bands from gene-specific A60

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325RETINOID-DEPENDENT POLY(A) MRNA CONTENTS IN BOVINE OOCYTES PREMATURED AND/OR MATURED IN VITRO

Reproduction Fertility and Development ◽

10.1071/rdv16n1ab325 ◽

2004 ◽

Vol 16 (2) ◽

pp. 282

Author(s):

L.J. Royo ◽

A. Rodriguez ◽

A. Gutierrez-Adan ◽

C. Diez ◽

E. Moran ◽

...

Keyword(s):

Cumulus Cells ◽

Defined Medium ◽

Developmental Competence ◽

Mrna Levels ◽

Atp Production ◽

Beneficial Effects ◽

Oocyte Developmental Competence ◽

Grant Support ◽

Bovine Oocytes

Retinoic acid (RA) can induce cell differentiation and plays a role in controlling events within the cell cycle, but little is known of RA post-transcriptional modifications in the oocyte. Bovine oocyte and cumulus cells express most of RA receptors, and the presence of 9-cis-RA during in vitro prematuration and maturation (IVM) improves oocyte developmental competence (Duque et al., 2002 Hum. Reprod. 17, 2706–2714; Hidalgo et al., 2003 Reproduction 125, 409–416). This work analyzes the mRNA stability in bovine oocytes during in vitro prematuration and/or maturation. Cumulus-oocyte complexes (COCs) were cultured in defined medium with polyvinyl alcohol (DM). Those COCs undergoing prematuration were cultured for 24h in DM with 25μM roscovitine. For IVM, COCs were cultured in DM containing pFSH, LH and E2 for 24h, and some prematured COCs were then allowed to mature. Incubations were made at 39°C in 5% CO2 in air and high humidity. Within experiments, COCs were cultured with 5nM 9-cis-RA, in 1% ethanol (both as a vehicle and as an inhibitor of endogenous RA synthesis), 3% ethanol, 5% ethanol and untreated. Groups of 10 COCs per treatment were cultured, and oocytes detached from cumulus cells were analyzed. Poly(A) mRNA quantification was based on the pyrophosphorylation property of the DNA polymerase (Klenow). ATP production was measured by luminometric assay as a function of numbers of poly(A) tails. Data (4 replicates) were analyzed by ANOVA and Duncan’s test (v,x,y,zP<0.01; a,bP<0.05), and poly(A) mRNA (pg oocyte−1) was expressed as LSM±SE. After prematuration, poly(A) mRNA contents differed between 9-cis-RA (125.7±4.8x) and untreated (95.5±4.8y) oocytes, as compared to 1% ethanol (72.2±4.8z) and immature (71.5±4.8z) oocytes. After IVM, untreated oocytes (23.0±2.2v) showed the lowest poly(A) mRNA amount, and poly(A) mRNA in 9-cis-RA (36.2±2.2y) basically equalled that in 1% ethanol (35.2±2.2y), while 3% (44.5±2.2yz) and 5% ethanol (52.0±2.2z) increased poly(A) mRNA levels. All groups of matured oocytes showed poly(A) mRNA contents lower than in immature (71.5±4.8x). After prematuration+maturation, poly(A) mRNA values were 34.2±2.2v (untreated+untreated), 36.5±2.2v (9-cis-RA+untreated), 49.5±2.2xa (untreated+9-cis-RA), 41.0±2.2vxb (9-cis-RA+9-cis-RA) and 59.0±2.2y (untreated+1% ethanol). Levels of poly(A) mRNA from prematured+matured oocytes were again lower than in immature (71.5±4.8x). Our study shows that beneficial effects of RA on the oocyte developmental competence can be represented in part as a gain in the quality of mRNAs stored. Grant support: Spanish Ministry of Science and Technology (AGL-2002-01175).

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The effects of cysteine addition during in vitro maturation on the developmental competence, ROS, GSH and apoptosis level of bovine oocytes exposed to heat stress

Zygote ◽

10.1017/s0967199411000220 ◽

2011 ◽

Vol 20 (3) ◽

pp. 249-259 ◽

Cited By ~ 50

Author(s):

Hisashi Nabenishi ◽

Hiroshi Ohta ◽

Toshihumi Nishimoto ◽

Tetsuo Morita ◽

Koji Ashizawa ◽

...

Keyword(s):

Heat Stress ◽

Formation Rate ◽

Cumulus Cells ◽

Developmental Competence ◽

Control Group ◽

Blastocyst Formation ◽

Nuclear Maturation ◽

Maturation Medium ◽

Bovine Oocytes

SummaryIn the present study, we investigated the effects of various concentrations of cysteine (0.0, 0.6, 1.2 and 1.8 mM) added to the maturation medium on nuclear maturation and subsequent embryonic development of bovine oocytes exposed to heat stress (HS: set at 39.5 °C for 5 h, 40.0 °C for 5 h, 40.5 °C for 6 h, and 40.0 °C for 4 h versus 38.5 °C for 20 h as the control group). This regime mimicked the circadian rhythm of the vaginal temperature of lactating dairy cows during the summer season in southwestern Japan. Moreover, we also evaluated the oocyte's reactive oxygen species (ROS) and glutathione (GSH) levels and the apoptosis levels of the oocytes and cumulus cells in the presence or absence of 1.2 mM cysteine. As a result, HS in the without-cysteine group significantly suppressed (p < 0.05) both the nuclear maturation rate up to the metaphase (M)II stage and the blastocyst formation rate compared with that of the control group. In addition, this group showed significantly higher (p < 0.05) ROS levels and significantly lower (p < 0.05) GSH levels than those of the control group. Moreover, the level of TdT-mediated dUTP nick end labelling (TUNEL)-positive cumulus cells in the HS without-cysteine group was significantly higher (p < 0.05) than that of the control group. However, the addition of 1.2 mM cysteine to the maturation medium restored not only the nuclear maturation, blastocyst formation rates and GSH contents, but also increased the ROS and TUNEL-positive levels of the cumulus cells, but not oocytes, to that of the control group. These results indicate that the addition of 1.2 mM cysteine during in vitro maturation (IVM) may alleviate the influence of heat stress for oocyte developmental competence by increasing GSH content and inhibiting the production of oocyte ROS followed by apoptosis of cumulus cells.

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Effects of Stem Cell Factor/c-Kit Signaling on In Vitro Maturation of Porcine Oocytes and Subsequent Developmental Competence After Fertilization

Frontiers in Veterinary Science ◽

10.3389/fvets.2021.745488 ◽

2021 ◽

Vol 8 ◽

Author(s):

Eunhye Kim ◽

Lian Cai ◽

Sang-Hwan Hyun

Keyword(s):

Stem Cell ◽

Mrna Expression ◽

Stem Cell Factor ◽

Polar Body ◽

Cumulus Cells ◽

Developmental Competence ◽

Control Group ◽

Secreted Factors ◽

Polar Body Extrusion

Stem cell factor (SCF), also known as c-Kit ligand, plays an important role in the proliferation of primordial germ cells and the survival of oocytes during follicular development. The aim of this study was to investigate the effect of SCF/c-Kit signaling on in vitro maturation (IVM) of porcine oocytes by analyzing nuclear and cytoplasmic maturation, oocyte size, cumulus cell expansion, and developmental competence to the blastocyst stage. Moreover, mRNA expression patterns of porcine cumulus cells and oocytes were evaluated using qRT-PCR. Following 42 h of IVM, 10 and 50 ng/mL SCF-treated groups exhibited significantly (P < 0.05) increased polar body extrusion rates and intracellular glutathione levels compared with the control group. The cumulus expansion index significantly (P < 0.05) increased in all SCF-treated groups compared with the control samples. mRNA levels of the proapoptotic gene Bax and apoptosis-related cysteine peptidase Caspase3 were lower in SCF-treated cumulus cells than in the control group. Notably, the diameter of oocytes after IVM, the mRNA expression of well-known oocyte-secreted factors (GDF9 and BMP15), and an oocyte-specific protein essential for ovulation and oocyte health (YBX2) were significantly (P < 0.05) higher in SCF-treated than in non-treated oocytes. Inhibition of c-Kit during porcine IVM using ACK2, an antagonistic blocker of c-Kit, significantly (P < 0.05) decreased the polar body extrusion rate compared with the control, as well as blastocyst formation rate compared with the 10 ng/mL SCF-treated group. In conclusion, the effect of SCF/c-Kit-mediated signaling during porcine IVM could be ascribed to the reduced expression of apoptosis-related genes and higher expression of oocyte-specific/secreted factors.

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Abilities of cumulus and granulosa cells to enhance the developmental competence of bovine oocytes during in vitro maturation period are promoted by midkine; a possible implication of its apoptosis suppressing effects

Reproduction ◽

10.1530/rep.1.01066 ◽

2006 ◽

Vol 132 (4) ◽

pp. 549-557 ◽

Cited By ~ 24

Author(s):

S Ikeda ◽

K Saeki ◽

H Imai ◽

M Yamada

Keyword(s):

Dna Fragmentation ◽

Granulosa Cells ◽

Cumulus Cell ◽

Cumulus Cells ◽

Blastocyst Stage ◽

Developmental Competence ◽

Control Group ◽

Blastocyst Development ◽

Bovine Oocytes

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.

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Heat Shock Protein 70 Improves In Vitro Embryo Yield and Quality from Heat Stressed Bovine Oocytes

Animals ◽

10.3390/ani11061794 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1794

Author(s):

Konstantina Stamperna ◽

Themistoklis Giannoulis ◽

Eleni Dovolou ◽

Maria Kalemkeridou ◽

Ioannis Nanas ◽

...

Keyword(s):

Gene Expression ◽

Heat Shock ◽

Heat Shock Protein ◽

Heat Shock Protein 70 ◽

Cumulus Cells ◽

Intramolecular Interactions ◽

Developmental Competence ◽

Embryo Yield ◽

Bovine Oocytes

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.

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Mechanism of the adverse effect of hyaluronidase used for oocyte denudation on early development of bovine embryos

Zygote ◽

10.1017/s0967199421000010 ◽

2021 ◽

pp. 1-5

Author(s):

Shiori Ashibe ◽

Kanade Irisawa ◽

Ken Yokawa ◽

Yoshikazu Nagao

Keyword(s):

Treatment Group ◽

Assisted Reproductive Technologies ◽

Cumulus Cells ◽

Reproductive Technologies ◽

Control Group ◽

Free Calcium ◽

Parthenogenetic Development ◽

Early Embryos ◽

Bovine Oocytes

Summary Hyaluronidase is widely used in animal and human assisted reproductive technologies (ARTs) to remove cumulus cells around oocytes. However, adverse effects of hyaluronidase treatment, such as increased rates of degeneration and parthenogenesis, have been found after treatment of human and mouse oocytes. Currently, the mechanism(s) of the detrimental effects are unclear. The present study was initiated to identify the mechanism of adverse responses to hyaluronidase treatment in bovine oocytes and early embryos. Cumulus cells were removed from cumulus–oocyte complexes (COCs) with or without hyaluronidase and the oocytes were subjected to intracytoplasmic sperm injection (ICSI) or in vitro fertilization (IVF). Significantly lower rates of blastocyst formation were obtained in the hyaluronidase treatment group after ICSI (22.4%) and IVF (21.2%) compared with the non-hyaluronidase control groups: 36.1% after ICSI and 30.4% after IVF. Next, we examined the effect of hyaluronidase on parthenogenetic development rates and on the cytoplasmic levels of free calcium ions (Ca2+), reactive oxygen species (ROS) and reduced glutathione (GSH). No differences in parthenogenesis rates were found between treated and untreated groups. Ca2+ levels in oocytes from the hyaluronidase treatment group indicated using mean fluorescence intensity were significantly higher (68.8 ± 5.3) compared with in the control group (45.0 ± 2.5). No differences were found in the levels of ROS or GSH between the treated and untreated groups. We conclude that hyaluronidase might trigger an increase in Ca2+ levels in oocytes, resulting in a decreased potential for normal embryonic development.

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346 BENEFICIAL EFFECTS OF ACETYL-l-CARNITINE TREATMENT DURING IVM ON POST-FERTILIZATION DEVELOPMENT OF BOVINE OOCYTES IN VITRO

Reproduction Fertility and Development ◽

10.1071/rdv18n2ab346 ◽

2006 ◽

Vol 18 (2) ◽

pp. 280 ◽

Cited By ~ 14

Author(s):

T. Yamada ◽

H. Imai ◽

M. Yamada

Keyword(s):

Energy Production ◽

Metabolic Regulation ◽

Cellular Proliferation ◽

Cumulus Cells ◽

Developmental Competence ◽

Acid Oxidation ◽

Oocyte Cytoplasm ◽

Peripheral Type ◽

Bovine Oocytes

The lower competence of in vitro-matured oocytes for post-fertilization development is attributed to the lack of physiological factors in in vitro maturation (IVM) that regulate maturation events which occur exclusively in the cytoplasm of oocytes. It has been found recently that mitochondrial function plays an important role in regulation of oocyte developmental competence via metabolic regulation of energy production. Acetyl-l-carnitine (ALC) is known to enhance fatty acid oxidation and energy production in the mitochondria, and to exert enhancing effects on cellular proliferation and survival. In this experiment, we examined the effects of ALC on IVM and post-fertilization development of bovine oocytes. Cumulus-oocyte complexs (COCs) were aspirated from 2-5 mm follicles of ovaries from a slaughterhouse. COCs were cultured in IVM medium (mSOFaa+estradiol+hCG+BSA) with or without ALC (10 mM) for 24 h at 39�C under 5% CO2 in air, and then fertilized according to the conventional method. After 6 h of insemination, presumptive zygotes were freed from cumulus cells by repeated pipetting and cultured in mSOFaa with 1% FCS at 39�C under 5% CO2, 5% O2, and 90% N2. At 48 h post-fertilization, the rates of cleaved embryos were assessed. The cleaved embryos were transferred to mSOFaa with 5% FCS and cultured for additional 6 days at 39�C under 5% CO2, 5% O2, and 90% N2. The percentages of embryos developing to the blastcyst stage were assessed on Days 6, 7, and 8 (fertilization = Day 0), and the data were analyzed for statistically significant differences with the t-test. For examinination of mitochondrial organization in oocytes at different maturation stages, oocytes were stained for active mitochondria with MitoRed (1 �M in IVM medium for 2 h at 37�). When COCs were matured in medium without (control) or with ALC, although the rates of post-fertilization cleavage of oocytes were 60% to 70% despite the presence or absence of ALC, ALC significantly (P < 0.05) increased the rates of cleaved embryos forming blastcysts on Days 6, 7, and 8 (30%, 36%, 40%) compared with those in the control (13%, 21%, 34%). We next examined effects of ALC treatment during IVM on active mitochondria distribution in oocytes. In 75% of immature oocytes, active mitochondria localized in the periphery of the oocytes (peripheral type). After 24 h of IVM without ALC, while 17% of oocytes remained in a peripheral type, 44% showed some migration of active mitochondria toward the center of the oocytes (semiperipheral type) and 39% presented a diffused distribution of active mitochondria in the whole oocyte cytoplasm (diffused type). On the other hand, in ALC treated oocytes, 60% of the oocytes presented a diffused type, 25% exhibited a semiperipheral type, and 15% had still maintained a peripheral distribution. These results provide the first evidence that ALC treatment during IVM of bovine oocytes enhances their post-fertilization development to the blastcyst stage and enhances the frequency of oocytes that exhibit an extensive relocation (diffused type) of active mitochondria to the inner oocyte cytoplasm.

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195 ALTERED mRNA TRANSCRIPT EXPRESSION OF IN VITRO- VERSUS IN VIVO-MATURED PORCINE OOCYTES

Reproduction Fertility and Development ◽

10.1071/rdv24n1ab195 ◽

2012 ◽

Vol 24 (1) ◽

pp. 210

Author(s):

L. D. Spate ◽

B. K. Redel ◽

K. M. Whitworth ◽

W. G. Spollen ◽

S. M. Blake ◽

...

Keyword(s):

Cell Cycle ◽

Real Time ◽

Real Time Pcr ◽

Genetic Background ◽

Cumulus Cells ◽

Developmental Competence ◽

Illumina Genome Analyzer ◽

Similar Genetic Background

In contrast to oocytes matured in vitro, porcine embryos that result from in vivo maturation and fertilization have a high developmental competence and readily make the transition from oocyte to blastocyst. This observation led us to investigate the transcript profile differences between in vivo- and in vitro-matured porcine oocytes. For the in vivo-matured group, oviducts of 3 gilts of similar genetic background were flushed 2 days after detection of standing oestrus. MII oocytes were collected in pools of 10 and snap frozen in liquid nitrogen for RNA isolation. The in vitro-matured oocytes were obtained by euthanizing 3 gilts, again with a similar genetic background and recovering the ovaries. Follicles (2 to 8 mm in size) were aspirated and oocytes with multiple layers of cumulus cells and uniform cytoplasm were placed in M-199 supplemented with LH, FSH and epidermal growth factor for 42 h. Upon maturation, cumulus cells were stripped and the healthy MII oocytes were collected in pools of 10 and snap frozen. Total RNA was extracted from 3 pools of 10 oocytes for both treatments using an All prep DNA/RNA micro isolation kit (Qiagen, Valencia, CA, USA). Complementary DNA was synthesized using oligo (dT′) primed reverse transcriptase with superscript III (Invitrogen, Carlsbad, CA, USA). Second-strand cDNA was synthesized using DNA polymerase I and sequenced using Illumina Genome Analyzer II. All reads were aligned to a custom-built porcine transcriptome. There were over 18 million reads in the 2 maturation groups that tiled to the 34 433-member transcriptome: 1317 transcripts were detected with a P ≤ 0.1 (Students t-test), a minimum of 7 reads in at least 1 of the treatments and ≥2-fold difference. Real-time PCR was used on selected transcripts. Comparative CT Method was used on an IQ real-time PCR system with the Bio–Rad SYBR green mix. Statistical differences were determined using the Proc general linear model procedure of SAS (SAS Institute Inc., Cary, NC) and means separated with a l.s.d. (P ≤ 0.05). The misrepresented transcripts from the sequencing data were also characterized using the functional annotation tool DAVID. Twelve pathways were overrepresented in the in vitro-matured oocytes (the top 4 are pathways to cancer, spliceosome, cell cycle and ubiquitin-mediated proteolysis). Eight pathways were underrepresented in the in vitro-matured oocytes (the top 4 are cytoskeleton regulation, T-cell receptor signaling pathway, ubiquitin-mediated proteolysis and cell cycle). Eight transcripts were selected for real-time PCR. ZP2 was higher in the in vitro-matured oocytes as determined by both sequencing and real time. ATG4, HSP90, UBAP2 and SOX4 were not different, regardless of assay. SLC7A3, MRPS36 and PDHX2 were not different based on sequencing, but based on real-time MRPS36 and PDHX2, were higher in the in vivo group and SLC7A3 was higher in the in vitro group. In conclusion, there is an abundance of misregulated transcripts and altered pathways in in vitro-matured oocytes. This dataset is a tool that may provide clues to improve the in vitro maturation process so that in vitro-matured oocytes will be more like their in vivo-matured counterparts, thus improving developmental competence. Funded by Food for the 21st Century.

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346 BOVINE EMBRYO DEVELOPMENT AFTER IVM/IVF/IVC OF OOCYTES STORED FOR 22 H IN VARIOUS MEDIA

Reproduction Fertility and Development ◽

10.1071/rdv19n1ab346 ◽

2007 ◽

Vol 19 (1) ◽

pp. 288

Author(s):

C. Kubota ◽

T. Kojima ◽

T. Nagai ◽

X. Tian ◽

X. Yang

Keyword(s):

Subsequent Development ◽

Industrial Applications ◽

Blastocyst Stage ◽

Developmental Competence ◽

Control Group ◽

Bovine Embryo ◽

Becton Dickinson ◽

In Vitro Storage ◽

Bovine Oocytes

The timing of IVM–IVF–IVC is restricted by the onset of oocyte maturation, and sometimes oocytes must be treated at midnight. If we could regulate the timing of IVM of oocytes without decreasing their developmental competence, the IVM–IVF–IVC system could be a more applied technology. The present study was performed to examine the effects of in vitro storage of bovine oocytes in simple media prior to maturation culture to manipulate the start of IVM. Bovine follicular fluid (bFF), Dulbecco's PBS (PBS), M199 Earle salts (M199), and Earle salts supplemented with 5 mM NaHCO3 (M199A) were used as the fundamental media, after an addition of antibiotics, for in vitro storage of bovine cumulus–oocyte complexes (COCs) collected from ovaries obtained at the slaughterhouse. The fundamental media except for bFF were supplemented with 10&percnt; fetal bovine serum (FBS) or 1 mg mL−1 polyvinyl alcohol (PVA). COCs were collected from follicles (3–8 mm in diameter) and washed twice in each medium; then approximately 50 COCs were submerged in 1 mL of each medium in cryotubes (Falcon #2812, 2.5 mL; Becton Dickinson Labware, Lincoln, NJ, USA), which were stored in a container kept at 38.5°C for 22 h under air-closed condition (in vitro storage: IVS). Subsequently, the stored COCs were in vitro-matured (IVM) for 22 h in M199 with 10&percnt; FBS and 20 µg mL−1 estradiol, fertilized (IVF), and cultured in CR1aa (IVC) for examination of their development to the blastocyst stage (Kubota et al. 1998 Mol. Reprod. Dev. 51, 281–286). Fresh oocytes without IVS were used as controls. The nuclear status of oocytes after IVS–IVM was compared to that of control oocytes by aceto-orcein stain. Their developmental rates to the blastocyst stage after IVM–IVF–IVC were compared between experimental and control groups. The experiment was repeated more than 3 times, and results were statistically analyzed using Student's t-test. When bFF and PBS supplemented with FBS or PVA were used for IVS, the rates of survived COCs after IVS and the development to the blastocyst stage after IVM–IVF–IVC (bFF (n = 87): 0&percnt;, 0&percnt;; PBS/FBS (n = 72): 84&percnt;, 1&percnt;; and PBS/PVA (n = 81): 89&percnt;, 6&percnt;, respectively) were significantly lower than those of the control group (n = 406; 97&percnt; and 29&percnt;, respectively). On the other hand, when M199A supplemented with FBS or PVA was used for IVS, the survival rate after IVS and the developmental rate to the blastocyst stage after IVS–IVM–IVF (M199A/FBS (n = 97): 82&percnt;, 28&percnt;; and M199A/PVA (n = 111): 98&percnt;, 31&percnt;, respectively) did not differ from those of the control group. After IVS, cumulus expansion was not seen and most of the oocyte nuclei reached the GVBD stage. These results suggest that the nuclear maturation progress of bovine oocytes can be regulated for at least 22 h in M199A without any deleterious influence on the number of oocytes surviving at an immature state after the storage and their subsequent development to the blastocyst stage after IVM–IVF–IVC. The delayed maturation allows a flexible fertilization schedule which is advantageous in research and industrial applications.

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