164 Evaluation of the lipid content of in vitro-matured bovine cumulus - oocyte complexes in the presence of natriuretic peptides A, B, and C types

2019 ◽  
Vol 31 (1) ◽  
pp. 207
Author(s):  
L. Schefer ◽  
K. R. L. Schwarz ◽  
H. Fernandes ◽  
D. M. P. Paschoal ◽  
F. C. C. Castro ◽  
...  
Keyword(s):  
Lipid Content ◽  
Natriuretic Peptides ◽  
Guanosine Monophosphate ◽  
Epifluorescence Microscopy ◽  
Control Group ◽  
In Vitro Production ◽  
Significance Level ◽  
Nuclear Maturation ◽  
Bovine Oocytes

One of the difficulties still observed in in vitro production (IVP) of bovine embryos is the lower cryotolerance of such embryos, which has been related to their increased lipid accumulation during culture in the presence of fetal bovine serum (FBS). Previous studies have indicated that the cyclic guanosine monophosphate (cGMP) pathway may be involved in the lipid metabolism of bovine cumulus-oocyte complexes (COC). Synthesis of cGMP can be caused by activation of membrane guanylate cyclase (mGC), also called natriuretic peptide receptors (NPR1 and NPR2), which are activated by natriuretic peptides (NP) A, B, and C types (NPPA, NPPB, and NPPC). The objective of this study was to investigate the influence of supplementation with NP during in vitro maturation (IVM) on lipid content and nuclear maturation of bovine COC. Pools of 25 COC were submitted to IVM in TCM-199 with 0.2mM sodium pyruvate, 10μg mL−1 gentamicide, 0.5μg mL−1 FSH, 10% FBS, and NPPA (10−5 M), NPPB (10−7 M), or NPPC (10−5 M). The control group was matured without NP. After 24h, cumulus cells (CC) were removed and oocytes (OO) were fixed and permeabilized in 4% paraformaldehyde+0.5% Triton for 20min, stained with 10μg mL−1 Hoechst 33342 for 15min and 1μg mL−1 Nile Red for 30min. Then, the OO were placed in 13μL of ProLong (Thermo Fisher Scientific, Waltham, MA, USA) on glass slides, covered with a coverslip, and submitted to epifluorescence microscopy to evaluate nuclear maturation (emission 445-450nm and excitation 475-490nm) and lipid content (emission 590nm and excitation 516-560nm). Data for 4 replicates/group were tested for normality of results and homogeneity of variance, and then submitted to ANOVA, followed by Tukey test using a GraphPad Prism software (GraphPad Inc., San Diego, CA, USA), with a significance level of 5%. Nuclear maturation was influenced only by one of the NP added to IVM medium, NPPC, which reduced maturation rate (68.3% metaphase II, MII) compared with the control (82.7% MII; P<0.05). Maturation rates of NPPA (79.5% MII) and NPPB (85.1% MII) did not differ from the control (P>0.05). Activation of mGC by NPPB generated oocytes with lower lipid content (34.02±1.2 IF/μm2) compared with control (36.98±0.7 IF/μm2; P<0.05). Neither NPPA (36.5±1.4 IF/μm2) nor NPPC (39.3±1.4 IF/μm2) was able to reduce the lipid content in oocytes matured in vitro relative to control (P>0.05). Different NP may have different effects on maturation and lipid content in in vitro matured bovine oocytes; NPPB may be favourable for reducing the lipid content of matured bovine oocytes in vitro.

282 DIFFERENT CONCENTRATIONS OF FORSKOLIN FOR MEIOSIS BLOCK AND TO IMPROVE IN VITRO PRODUCTION OF BOVINE EMBRYOS

2015 ◽  
Vol 27 (1) ◽  
pp. 230
Author(s):  
D. Paschoal ◽  
R. Maziero ◽  
M. Sudano ◽  
M. Guastali ◽  
L. Crocomo ◽  
...  
Keyword(s):  
Embryonic Development ◽  
Least Squares ◽  
Control Group ◽  
In Vitro Production ◽  
Intact Cells ◽  
Significance Level ◽  
Nuclear Maturation ◽  
Oocyte Meiosis ◽  
Group Control

The inhibition of nuclear maturation allows time for the oocyte to accumulate molecules that are important for embryonic development. It was suggested that the inhibition of spontaneous nuclear IVM might allow for more time to accumulate the molecules important for embryonic development. The objective of this work was to evaluate blocking oocyte meiosis with the addition of forskolin. Slaughterhouse-derived bovine Zebu ovaries were collected and carried to the laboratory. Oocytes (n = 584) with at least 3 intact layers of cumulus cells and homogeneous cytoplasm were selected for IVM. The oocytes were transferred to drops of TCM 199 plus 10% FCS and hormones. The oocytes remained in IVM medium in 3 different concentrations of forskolin (6886), 0.1, 0.05, 0.025 mM, and a control group (withouth forskolin), for 6 h. Then they were maturated for an additional 18 h in forskolin-free medium. The first period above was an attempt to block (Block) and the second to resume (Res) the oocyte meiosis. The oocytes were incubated in a humidified atmosphere with 5% CO2 at 38.5°C in an air incubator. The oocytes were assessed for the stage of nuclear maturation, to see if they were in M II. Then oocytes were in vitro fertilized (IVF) with frozen Nelore bull semen (Bos taurus indicus). Presumptive zygotes (20–30/group) were cultured in SOFaa (synthetic oviducal fluid) supplemented with 5 mg mL–1 of BSA; the embryos were kept in an incubator with 5% CO2, 5% O2, and 90% N2 at 38.5°C and absolute humidity. On Day 7 (Day 0 = IVF) the blastocyst, the number of viable cells, and apoptosis rate (terminal deoxynucleotide transferase uridine nick-end labelling) were observed. Data were analysed with ANOVA using SAS PROC GLM (SAS Inst. Inc., Cary, NC, USA). Sources of variation in the model, including treatment and replication, were respectively considered fixed and random effects. If ANOVA was significant, the contrasts of means were performed using the least-squares difference. Data are presented as the mean and the standard error of least-squares. For all analyses, we used a significance level of 5%. No differences were observed for the stage of nuclear maturation of the oocyte (N = 336; control: 67.7 ± 8.3; F 0.025 mM, Block/Res: 67.7 ± 8.9; F 0.05 mM, Block/Res: 65.9 ± 9.8; F 0.1 mM, Block/Res: 50.2 ± 8.9), the blastocyst rate (N = 584; Control: 36.7 ± 3.7; F0.025 mM, Block/Res: 32.6 ± 3.7; F0.05 mM, Block/Res: 29.2 ± 3.7; F0.1 mM, Block/Res: 25.1 ± 3.7), and total number of intact cells (N = 10–15 embryos/group; Control:140.1 ± 13.0; F0.025 mM, Block/Res: 129.9 ± 13.0; F0.05 mM, Block/Res: 139.0 ± 13.0; F0.1 mM, Block/Res: 104.4 ± 13.0; P > 0.05). However, a higher rate of apoptosis was observed in the blastocysts produced from oocytes blocked for 6 h with the higher concentration of forskolin (N = 10–15 embryos/group): Control: 12.1 ± 2.5a; F 0.025 mM, Block/Res: 12.9 ± 2.5a; F0.05 mM, Block/Res: 13.5 ± 2.5a; F 0.1 mM, Block/Res: 30.2 ± 2.5b (P < 0.05). We conclude that all the experimental groups reached the stage of M II after the addition of forskolin and the highest concentration of forskolin caused cellular degeneration without harming embryo production on the seventh day.

277 LIPID ACCUMULATION DURING BOVINE OOCYTES Gyr/HOLSTEIN MATURATION COLLECTED BY OPU IN SPOM SYSTEM

2015 ◽  
Vol 27 (1) ◽  
pp. 227
Author(s):  
G. R. Leal ◽  
C. A. S. Monteiro ◽  
H. F. R. A. Saraiva ◽  
A. J. R. Camargo ◽  
C. O. P. Vasconcelos ◽  
...  
Keyword(s):  
Lipid Content ◽  
Lipid Accumulation ◽  
Lipid Analysis ◽  
Fold Increase ◽  
Control Group ◽  
Sodium Pyruvate ◽  
Nuclear Maturation ◽  
Tropical Conditions ◽  
Bovine Oocytes

In vitro embryo production (IVP) is an important tool for cattle breeding. Brazilian dairy systems are based on Gyr/Holstein crossbreds, which integrates adaptability to tropical conditions and milk production. Oocyte quality is crucial for IVP, and lipid accumulation is a detrimental factor. The aim of this study was to assess the effect of SPOM maturation system (Albuz et al. 2010 Hum. Reprod. 25) on lipid accumulation in bovine oocytes. Oocytes obtained by ovum pick-up (OPU) from heifers without ovarian stimulation were transferred to control media (TCM 199 + sodium pyruvate, ITS, penicillin-streptomycin, BSA, FSH, oestrogen, and hCG) or SPOM (2 h pre-IVM: TCM 199 hepes + sodium pyruvate, ITS, penicillin-streptomycin, BSA, IBMX, and forskolin; followed by 28 h IVM: control media + cilostamide) in 5% CO2 atmosphere at 38°C. Oocytes were collected after 20, 24, and 28 h (groups: C20, C24, C28; S20, S24, S28) and evaluated for nuclear maturation using HOECHST (experiment 1, n = 301, 35–62 per group) and lipid content using Oil Red (experiment 2, n = 163, 14–42 per group). Oocytes from 4 replicates were fixed with PFA and stored at 4°C. For Oil Red, all structures were stained and evaluated at the same day. After being washed in 50% ethanol, oocytes were incubated in 0.2% Oil Red O solution for 10 min. Stained area fraction in each oocyte cytoplasm was measured using ImageJ (NIH). Nuclear maturation analysis was performed by Chi-squared test and Lipid analysis by Kruskal-Wallis and Dunn's post-test (P = 0.05). Distinct superscript letters indicate statistical difference between groups. In experiment 1, we detected a reduction in the percentage of matured (MII) oocytes only in S20 group (C20 = 64.28%a, C24 = 74.28%a, C28 = 60.46%a, S20 = 25.8%b, S24 = 59, 01%a, S28 = 74.13%a). In experiment 2, we detected an increase in lipid content in both control and SPOM groups from 20 to 28 h of IVM (S20 = 5.72a ± 4.41, S24 = 15.95bd ± 7.41, S28 = 37.46c ± 8.68, C20 = 8.65a ± 2.58, C24 = 12.14ad ± 8.08, C28 = 18.50b ± 8.09). For SPOM groups, the lipid content increased 2.78-fold from S20 to S24, and 6.54-fold from S20 to S28. In the control group, only in C28 wasa lipid increase detected, 2.13-fold higher than C20 content. Comparing control and SPOM groups at each time point, S28 displayed a 2.02-fold increase in lipid content compared to C28. We concluded that despite SPOM system being effective in maintaining meiotic arrest until 20 h of IVM and forskolin being present during pre-IVM in SPOM groups, Gyr/Holstein crossbreed oocytes obtained by OPU presented a significant increase in lipid content when matured in SPOM system, even higher than observed for the control group. During the last 8 h of IVM we observed a huge lipid accumulation in both systems, suggesting this might be a crucial period.

172 Effect of Melatonin on Meiosis Progression and Lipid Content in Bovine Oocytes Matured In Vitro

2018 ◽  
Vol 30 (1) ◽  
pp. 225
Author(s):  
H. Fernandes ◽  
L. Schefer ◽  
F. C. Castro ◽  
D. M. Paschoal ◽  
R. C. Botigelli ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Lipid Content ◽  
Negative Control ◽  
Epifluorescence Microscopy ◽  
Maturation Stage ◽  
Nuclear Maturation ◽  
Positive Effects ◽  
Lipid Contents ◽  
Bovine Oocytes

Melatonin (MLT) may have positive effects on oocyte nuclear maturation and may influence their lipid metabolism. The aim of this study was to assess the effect of MLT on nuclear maturation and lipid content inbovine oocytes during in vitro maturation (IVM). Cumulus-oocyte complexes (30-35/group) were submitted to IVM in TCM-199 supplemented with 3 mg mL−1 BSA (negative control; NC) or with added hormones: 1 µg mL−1 FSH (positive control; PC) or MLT (10−11, 10−9 and 10−7 M), to evaluate the individual action of each treatment on meiosis resumption (metaphase I, MI) at 9 h and progression to metaphase II (MII) at 24 h IVM. Lipid content in oocytes was also assessed. Oocytes were denuded and stained with Hoechst 33342 and Nile Red, and evaluated by epifluorescence microscopy to determine the nuclear maturation stage and lipid content, respectively. The fluorescence intensity (FI) was measured by ImageJ software (National Institutes of Health, Bethesda, MD, USA). Data were analysed by ANOVA followed by Tukey’s test to compare effects of treatments on meiosis resumption and lipid contents at 9 h and on meiosis progression and lipid contents at 24 h; and t-test to compare the same treatment at 9 and 24 h IVM regarding lipid contents (4 replicates/treatment). Significance level was 5% (GraphPrism software; GraphPad Inc., San Diego, CA, USA). At 9 h IVM, meiosis resumption rate (MI) increased (P < 0.05) for MLT 10−9 M (32.6 ± 14.8%, 45/138) and FSH groups (33.9 ± 18.1%, 38/112) compared with NC (4.2 ± 2.7%, 5/120). The other treatments did not differ in relation to NC (20.5 ± 12.5%, 27/132 and 14.9 ± 9.0%, 20/134 to MLT 10−11 and 10−7 M, respectively). Regarding lipid contents at 9 h, MLT 10−11 M showed higher lipid content (8.43 ± 7.61FI; P < 0.0001) compared with other treatments [MLT 10−9 M (5.59 ± 4.13), MLT 10−7 M (4.87 ± 3.21), FSH (5.34 ± 3.66), and NC (4.27 ± 3.28)]. Maturation rate (MII) at 24 h IVM was highest in FSH group (70.1 ± 10.2%, 94/134). No differences were observed (P > 0.05) between groups matured in different concentrations of MLT (65.9 ± 4.2%, 83/126; 62.2 ± 0.6%, 56/90 and 53.5 ± 10.0%, 61/114 for MLT 10−11, 10−9 and 10−7 M, respectively) compared with NC (86.3 ± 1.2%, 88/102; P < 0.05). Similarly, lipid content at 24 h IVM was higher (P < 0.05) in FSH group (10.72 ± 4.71 FI) compared with NC (7.98 ± 3.45 FI) or MLT treatments with 10−11 M (8.90 ± 3.91), 10−9 M (7.85 ± 3.56), and 10−7 M (8.29 ± 3.87). However, MLT 10−7 M, FSH, and NC groups had higher (P < 0.0001) lipid content at 24 than at 9 h. In conclusion, MLT 10−9 M alone was able to stimulate meiosis resumption (9 h) at a rate similar to FSH, but was insufficient to stimulate progression to MII at 24 h, indicating that it may affect nuclear maturation only during the initial steps of meiosis. Lipid contents were increased during IVM but for lower MLT concentrations, this increase was not observed. Whether these observations have any impact on oocyte quality remains to be determined. Further studies are necessary to improve our knowledge of the role of MLT on lipid metabolism and by which mechanism it may affect meiosis resumption in bovine oocytes. This research was funded by FAPESP (HF- 2016/24884-3, scholarship; CLVL, financial support 2015/20379-0).

Treatment with roscovitine and butyrolactone I prior to in vitro maturation alters blastocyst production

Zygote ◽  
2019 ◽  
Vol 28 (1) ◽  
pp. 24-31 ◽  
Author(s):  
Rosiara Rosária Dias Maziero ◽  
Carlos Renato de Freitas Guaitolini ◽  
Daniela Martins Paschoal ◽  
André Maciel Crespilho ◽  
Bianca Andriolo Monteiro ◽  
...  
Keyword(s):  
In Vitro Maturation ◽  
Study Groups ◽  
Embryo Cryopreservation ◽  
Control Group ◽  
Bovine Embryos ◽  
Nuclear Maturation ◽  
Oocyte Meiosis ◽  
Maturation Index ◽  
Bovine Oocytes

SummaryThis study evaluated the effects of oocyte meiosis inhibitors roscovitine (ROS) and butyrolactone I (BL-I) on in vitro production of bovine embryos. Bovine oocytes were maintained in pre in vitro maturation (pre-IVM) with 25 µM ROS or 100 µM BL-I for 24 h to delay meiosis and for 24 h in in vitro maturation (IVM). Following this treatment, the nuclear maturation index was evaluated. All embryos degenerated following this procedure. In the second set of experiments, oocytes were maintained for 6 or 12 h in pre-IVM with the following three treatments: ROS (25 µM or 12.5 µM), BL-I (100 µM or 50 µM) or a combination of both drugs (6.25 µM ROS and 12.5 µM BL-I). Oocytes were cultivated for 18 or 12 h in IVM. When a meiosis-inducing agent was used during pre-IVM for 24 h, more degenerated oocytes were observed at the end of the IVM period. This effect decreased when the meiotic blocking period was reduced to 6 or 12 h. No significant differences were observed in the blastocyst production rate of oocytes in pre-IVM for 6 h with ROS, BL-I, or ROS + BL-I compared with that of the control group (P > 0.05). However, inhibition of oocytes for 12 h resulted in decreased embryo production compared with that in the controls (P < 0.05). There was no difference in the post-vitrification embryo re-expansion rate between the study groups, showing that the meiotic inhibition for 6 or 12 h did not alter the embryo cryopreservation process.

165 FETAL CALF SERUM INFLUENCES CYCLIC GMP PATHWAY, WHICH IN TURN AFFECTS THE LIPID CONTENT IN IN VITRO-MATURED BOVINE OOCYTES

2014 ◽  
Vol 26 (1) ◽  
pp. 196
Author(s):  
K. R. L. Schwarz ◽  
R. C. Botigelli ◽  
F. C. Castro ◽  
M. R. Chiaratti ◽  
C. L. V. Leal
Keyword(s):  
Lipid Content ◽  
Fetal Calf Serum ◽  
Calf Serum ◽  
Cumulus Cells ◽  
Control Group ◽  
Maturation Medium ◽  
Cgmp Pathway ◽  
Bovine Oocytes ◽  
Synthesis And Degradation

The sensitivity of IVP embryos to cryopreservation is often associated with lipid accumulation in the cytoplasm induced by the presence of fetal calf serum (FCS) during culture. Intracellular levels of cyclic (c)AMP and cGMP are involved in the regulation of lipolysis in adipocytes; high levels stimulate lipolysis whereas low levels lead to lipogenesis. Both nucleotides are present in bovine oocytes, together with the enzymes for their synthesis and degradation. The aim of this study was to analysis the effect of FCS on the cGMP pathway and the influence of cGMP on cytoplasmic lipids in bovine oocytes. In experiments 1 and 2, cumulus–oocyte complexes (COC) were cultured for 24 h in maturation medium with different proportions of FCS (2 and 10%) and a control group was matured with 0.4% BSA. After this period, transcripts for cGMP pathway were assessed by real-time PCR (GUCY1B3 and PDE5, cGMP synthesis and degradation enzymes, respectively; experiment 1) in oocytes and cumulus cells, and cGMP levels were measured in COC using commercial enzyme immunoassay kits (EIA; experiment 2). In experiments 3 and 4, COC were matured for 24 h with 0.4% BSA and different concentrations of the phosphodiesterase (PDE)5 inhibitor (0, 10–7, and 10–5 M sildenafil) to inhibit cGMP degradation and a control group was matured with 0.4% BSA. The nucleotide levels were measured in COC (experiment 3) and the oocytes were stained with Nile Red (1 μg mL–1) for evaluation of lipid content (experiment 4). Statistical analyses were performed by ANOVA followed by Tukey post hoc test using SAS software (SAS Institute Inc., Cary, NC, USA). Data for gene expression from 5 replicates and for cGMP measurements and lipid content from 3 replicates were log10-transformed into before analyses. The level of significance was 5%. The presence of FCS reduced GUCY1B3 expression in both cells and increased PDE5A in cumulus cells (P < 0.05). In experiment 2, the groups treated with 2 (0.64 fmol/COC) and 10% FCS (1.04 fmol/COC) showed decreased cGMP levels compared with control (9.46 fmol/COC; P < 0.05). In experiment 3, inhibition of PDE5A increased cGMP levels in the treated groups (36 and 56 fmol/COC for 10–7 and 10–5 M sildenafil, respectively) compared with control (9.5 fmol/COC; P < 0.05). Therefore, sildenafil showed inverse effects compared with FCS (experiment 2). In experiment 4, oocytes treated with 10–7 and 10–5 M sildenafil showed a reduced lipid content compared with controls (11.6 ± 9.4 v. 13.9 μm2 fluorescence intensity, respectively; P < 0.05). The results suggest that FCS in maturation medium affects the cGMP pathway, interfering with the transcription of genes that control its levels, which in turn results in nucleotide reduction. Inhibition of PDE5 increases cGMP levels and reduces the lipid content of oocytes, indicating that changes in this pathway caused by FCS may affect lipid metabolism of oocytes. More studies are underway to better understand this mechanism. The authors acknowledge FAPESP 2012/00170-0 for financial support.

116 EFFECTS OF l-GLUTAMINE ON CRYOPRESERVATION OF IMMATURE BOVINE OOCYTES

2006 ◽  
Vol 18 (2) ◽  
pp. 167
Author(s):  
C. Yamada ◽  
M. D. Goissis ◽  
H. V. A. Caetano ◽  
A. R. S. Coutinho ◽  
M. E. O. A. Assumpção ◽  
...  
Keyword(s):  
Amino Acids ◽  
In Vitro Maturation ◽  
Complex Structure ◽  
Cumulus Cell ◽  
Epifluorescence Microscopy ◽  
Control Group ◽  
Maturation Medium ◽  
Cell Layers ◽  
Bovine Oocytes

The cryopreservation of bovine oocytes remains a challenge despite significant reported progress. Immature bovine oocytes have a complex structure and the conventional cryoprotectants (penetrating cryoprotectants, sugars, and macromolecules) appear to be not sufficient to preserve them efficiently during freezing. Studies on semen and fibroblast cryopreservation indicate that amino acids, particularly l-glutamine, protect enzymes during freezing and increase the post-thaw viability. Therefore, the amino acids may optimize oocyte cryopreservation when associated with conventional cryoprotectants. This work evaluated the effect of l-glutamine on cryopreservation of immature bovine oocytes after in vitro maturation. Oocytes with homogeneous cytoplasm and several cumulus cell layers from slaughterhouse ovaries were distributed randomly in three groups: non-vitrified control, vitrified control, and vitrified with l-glutamine. Oocytes from vitrified groups were exposed for 10 min to PBS + 10% FCS + 10% ethylene glycol (EG) + 0.25 m trehalose (T), and for 30 s to PBS + 10% FCS + 25% EG + 25% dimethylsulfoxide + 0.5 m T at room temperature, adding 80 mm l-glutamine for the third group. Oocytes were loaded into OPS and plunged in liquid nitrogen. For thawing, OPS were immersed in PBS + 10% FCS + 10% EG + 1 m T for three min. Oocytes werethen placed in PBS + 10% FCS + 0.5 m T and in PBS + 10% FCS, remaining three min in each solution. For in vitro maturation, oocytes were washed three times on holding medium (TCM-HEPES + FCS + pyruvate + gentamycin), washed three times in maturation medium (TCM-bicarbonate + FCS + pyruvate + gentamycin + hCG + FSH + estradiol), and cultured in microdrops (90 μL) of maturation medium covered with mineral oil at 38.5°C under 5% CO2 in air and high humidity for 24 h. Oocytes were denuded, fixed in paraformaldehyde and triton, stained with Hoechst 33342, and evaluated under epifluorescence microscopy. Oocytes at metaphase II were considered matured. The group vitrified with l-glutamine had a significantly higher maturation rate than the group vitrified without l-glutamine; however, both had significantly lower maturation rates than the non-vitrified control group. In conclusion, l-glutamine improved the viability of vitrified oocytes. Table 1. Oocyte maturation rates of non-vitrified control, vitrified control, and vitrified with glutamine groups This work was supported by FAPESP 03/08543-1.

329 SUPPRESSION OF BOVINE OOCYTE IVM BY SERUM AND FSH DEPRIVATION OR BY α-AMANITIN: EFFECT ON FERTILIZATION AND EMBRYO DEVELOPMENT

2006 ◽  
Vol 18 (2) ◽  
pp. 272
Author(s):  
K. Kananen-Anttila ◽  
M. Eronen ◽  
J. Matilainen ◽  
M. Kallio ◽  
J. Peippo ◽  
...  
Keyword(s):  
Embryo Development ◽  
Cumulus Cell ◽  
Developmental Competence ◽  
Control Group ◽  
Blastocyst Development ◽  
Nuclear Maturation ◽  
Embryo Cleavage ◽  
Bovine Oocytes ◽  
Sperm Aster

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

355 INFLUENCE OF NITRIC OXIDE AND CYCLIC GMP SIGNALING PATHWAY ON THE IN VITRO MATURATION OF BOVINE OOCYTES: PRELIMINARY RESULTS

2010 ◽  
Vol 22 (1) ◽  
pp. 334
Author(s):  
K. R. L. Schwarz ◽  
T. H. C. de Bem ◽  
P. R. L. Pires ◽  
L. G. Mesquita ◽  
L. Remy ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Signaling Pathway ◽  
Polar Body ◽  
Calf Serum ◽  
Guanosine Monophosphate ◽  
No Donor ◽  
Nuclear Maturation ◽  
First Polar Body ◽  
Bovine Oocytes

Nitric oxide (NO) is a chemical messenger generated by the activity of the nitric oxide synthase enzyme (NOS) and has been shown to be involved in oocyte maturation. NO is known to act through the guanylate cyclase (GC) signaling pathway, stimulating the production of cyclic guanosine monophosphate (cGMP), which in turn activates protein kinase G (PKG). The objective of the present study was to investigate the involvement of NO and GC/cGMP/PKG pathway on the IVM of bovine oocytes. Slaughterhouse ovaries were transported to the laboratory and oocytes were aspirated from 2 to 8 mm follicles. Oocytes were submitted to IVM (TCM-199+10% fetal calf serum + hormones) for 24 h (38.5°C and 5% CO2 in air) and were assessed for nuclear maturation by acetic-orcein (1%) staining. Maturation rates were analyzed by ANOVA. Five replicates were performed with 20 oocytes per group per replicate. When the oocytes were matured with the NO donor [(0, 10-9, 10-8 and 10-7M S-nitroso-N-acteyl-D,L- penicillamine (SNAP)] germinal vesicle break down (GVBD) rates after 7 h in IVM were 36, 31, 42, and 24%, respectively (P > 0.05). Maturation rates after 24 h IVM ranged from 80 to 85% (P > 0.05). The inhibition of GC [(0, 0.1, 10, and 100 μM 1, H-[1, 2, 4]oxadiazole[4, 3-a]quinoxalon-1-one (ODQ)] and PKG (0, 1, 10, and 100 μM KT5823) did not affect (P > 0.05) the ability of oocytes to form the first polar body (average of 83 and 88%, respectively). When the cGMP-analogue (0, 1, 2, and 4 mM 8-Bromo-cGMP) and the GC-stimulator (0, 5, 10, and 50 μM Protoporphyrin IX) were used during IVM, maturation rates were over 85% in all groups (P > 0.05). To confirm the lack of effect of the inhibitors, another evaluation with higher concentrations of inhibitors in semi-defined IVM medium (TCM-199 + 0.04% BSA) was carried out. Maturation rates were 70 to 75% (P > 0.05) with ODQ and 57 to 76% (P > 0.05) with KT5823. The evaluation with the GC stimulator and the cGMP analogue in semi-defined medium is currently underway. In conclusion, under the conditions studied, the GC/cGMP/PKG signaling pathway is not involved in the nuclear maturation of bovine oocytes. Supported by FAPESP, Brazil.

289 THE EFFECTS OF MEIOSIS BLOCKING BY CDK INHIBITORS ON THE ACTIVITY OF MATURATION PROMOTING FACTOR, ERK1 AND 2, AND THE DISTRIBUTION OF CYTOPLASMIC ORGANELLES IN IN VITRO-MATURED BOVINE OOCYTES

2015 ◽  
Vol 27 (1) ◽  
pp. 233
Author(s):  
R. R. D. Maziero ◽  
C. R. F. Guaitolini ◽  
D. M. Paschoal ◽  
A. M. Crespilho ◽  
F. C. Landim-Alvarenga
Keyword(s):  
Cyclin B1 ◽  
Oocyte Quality ◽  
Control Group ◽  
Cdk Inhibitors ◽  
Cortical Granules ◽  
Immature Oocytes ◽  
Nuclear Maturation ◽  
Cytoplasmic Organelles ◽  
Bovine Oocytes

Studies have suggested that the prematuration with meiotic blockers can improve oocyte quality promoting embryonic development; however, its exact effects on cytoplasmic characteristics remain unclear. Thus, this study aimed to evaluate the effects of meiosis block of bovine oocytes with the CDK inhibitors roscovitine (ROS) and butyrolactone (BL-I) on nuclear maturation, expression, and localization of ERK 1 and 2, cyclin B1, and p34cdc2 proteins and the ultrastructure of oocytes. Immature oocytes from the slaughterhouse were divided into the following groups: (1) control, in vitro maturated (IVM) in TCM 199 for 24 h; (2) ROS 12.5 µM; (3) BL-I 50 µM; and (4) ROS (6.25 µM) + BL-I (25 µM) treatment for 6 h followed by IVM in CDK inhibitor-free medium for 18 h. Immature oocytes and IVM oocytes in each group were then fixed stained by immunofluorescence for nuclear visualisation (n = 600), localization, and expression of ERK1 and 2 proteins, cyclin B1 and p34cdc2 protein (n = 350), and prepared for evaluation of the ultrastructure by electron microscopy (n = 100). Data were analysed using the ANOVA test (nuclear visualisation), Student-Newman-Keuls test (expression of ERK1 and 2 proteins, cyclin B1 and p43cdc2) by the PROC GLM procedure of SAS (SAS Inst. Inc., Cary, NC, USA). At 6 h of IVM, a lower (P < 0.05) percentage of oocytes were at the metaphase I (MI) stage in the control group (C = 18.2 ± 5.4%) compared with other groups and a higher percentage of oocytes were degenerated in the ROS group (16.3 ± 5.6%) compared with other groups (C = 13.6 ± 4.6%, BL-I = 10.0 ± 4.5%, BL-I+ROS = 8.0 ± 5.6%). At 24 h of IVM, higher (P < 0.05) percentages of oocytes were at the MI stage in the control and ROS group (8.3 ± 5.9% and 6.8 ± 6.4%, respectively). There was no difference (P > 0.05) in percentage of metaphase II (MII) oocytes among the groups. Only the ROS group showed lower fluorescence intensity of ERK1 and 2 proteins in the ooplasma (P < 0.05). Immature oocytes showed higher expression of cyclin B1 and p34cdc2 (P < 0.05). There was no difference in the localization of these proteins in the ooplasm and there was no difference in the oocyte ultrastructure (mitochondria, cortical granules, endoplasmic reticulum, microvilli, zona pellucida, lipid granules) among treatments (P > 0.05). The results suggest that a temporary blocking of oocyte maturation by CDK inhibitors affect neither the expression and distribution of MPF components (cyclin B1/cdc2) nor the distribution of cytoplasmic organelles in IVM oocytes. However, the expression of ERK 1 and 2 in mature oocytes may be reduced by pre-IVM with ROS.

Effects of ghrelin on activation of Akt1 and ERK1/2 pathways during in vitro maturation of bovine oocytes

Zygote ◽  
2017 ◽  
Vol 25 (2) ◽  
pp. 183-189 ◽  
Author(s):  
Thomas-Markos Chouzouris ◽  
Eleni Dovolou ◽  
Fotini Krania ◽  
Ioannis S. Pappas ◽  
Konstantinos Dafopoulos ◽  
...  
Keyword(s):  
Oocyte Maturation ◽  
Cumulus Cells ◽  
Treated Group ◽  
Control Group ◽  
Dependent Manner ◽  
Nuclear Maturation ◽  
Bovine Oocytes ◽  
Phosphorylation Rate ◽  
Matured Oocyte

SummaryThe purpose of this study was to investigate the possible molecular pathways through which ghrelin accelerates in vitro oocyte maturation. Bovine cumulus–oocyte complexes (COCs), after 18 or 24 h maturation in the absence or the presence of 800 pg ml–1 of acylated ghrelin were either assessed for nuclear maturation or underwent in vitro fertilization in standard media and putative zygotes were cultured in vitro for 8 days. In a subset of COCs the levels of phosphorylated Akt1 and ERK1/2 (MAPK1/3) were assessed at the 0th, 6th, 10th, 18th and 24th hours of in vitro maturation (IVM). At 18 and 24 h no difference existed in the proportion of matured oocytes in the ghrelin-treated group, while in the control group more (P < 0.05) matured oocyte were found at 24 h. Oocyte maturation for 24 h in the presence of ghrelin resulted in substantially reduced (P < 0.05) blastocyst yield(16.3%) in comparison with that obtained after 18 h (30.0%) or to both control groups (29.3% and 26.9%, for 18 and 24 h in maturation, respectively). Ghrelin-treated oocytes expressed lower Akt1 phosphorylation rate at the 10th hour of IVM, and higher ERK1/2 at the 6th and 10th hours of IVM compared with controls. In cumulus cells, at the 18th and 24th hours of IVM Akt1 phosphorylation rate was higher in ghrelin-treated oocytes. Our results imply that ghrelin acts in a different time-dependent manner on bovine oocytes and cumulus cells modulating Akt1 and ERK1/2 phosphorylation, which brings about acceleration of the oocyte maturation process.

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