Lipid Content Of Embryos Research Articles

Influence of maternal obesity on embryonic vitrification injury and subsequent pregnancy outcomes: A retrospective cohort study

BackgroundWe previously reported that obese mice had significantly high lipid content in embryos, and excessive lipids are detrimental to embryonic development. However, whether maternal obesity has an effect on embryonic vitrification injury and subsequent pregnancy outcomes is still controversial. This study was conducted to clarify the influence of maternal obesity on embryonic vitrification injury and subsequent pregnancy outcomes by in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI). MethodsWe retrospectively collected medical record of IVF/ICSI patients from reproductive medicine centers in two tertiary hospitals. The patients were classified into a low-weight group (<18.5 kg/m2), normal-weight group (18.5–23.9 kg/m2), overweight group (24.0–27.9 kg/m2) and obese group (≥28.0 kg/m2) according to their body mass index (BMI). Multivariable logistic regression analysis was performed to compare pregnancy outcomes in fresh and frozen embryo transfer among different BMI groups to define the correlation between BMI and embryonic vitrification injury. ResultsA total of 44 773 women among 20–40 years old were recruited in this study, of which 27 797 underwent their first fresh embryo transfer and 16 976 underwent their first frozen embryo transfer. For fresh embryo transfer, there was no significant difference in the clinical pregnancy rate, live birth rate, and miscarriage rate of 4 BMI groups. For frozen-thawed embryo transfer, there was a significant increase in the clinical pregnancy rate of the overweight group (AOR = 1.14, 95% CI: 1.05–1.25) and the obese group (AOR = 1.24, 95% CI: 1.03–1.50), while the miscarriage rate (AOR = 1.42, 95% CI: 1.05–1.92) also showed a significant increase in the obese group compared to the normal-weight group. ConclusionThis study provided a new understanding of the effect of maternal obesity on embryonic vitrification injury. Maternal obesity does not worsen the outcome of IVF/ICSI, particularly in the frozen-thawed group.

The PRK/Rubisco shunt strongly influences Arabidopsis seed metabolism and oil accumulation, affecting more than carbon recycling.

The carbon efficiency of storage lipid biosynthesis from imported sucrose in green Brassicaceae seeds is proposed to be enhanced by the PRK/Rubisco shunt, in which ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) acts outside the context of the Calvin-Benson-Bassham cycle to recycle CO2 molecules released during fatty acid synthesis. This pathway utilizes metabolites generated by the nonoxidative steps of the pentose phosphate pathway. Photosynthesis provides energy for reactions such as the phosphorylation of ribulose 5-phosphate by phosphoribulokinase (PRK). Here, we show that loss of PRK in Arabidopsis thaliana (Arabidopsis) blocks photoautotrophic growth and is seedling-lethal. However, seeds containing prk embryos develop normally, allowing us to use genetics to assess the importance of the PRK/Rubisco shunt. Compared with nonmutant siblings, prk embryos produce one-third less lipids-a greater reduction than expected from simply blocking the proposed PRK/Rubisco shunt. However, developing prk seeds are also chlorotic and have elevated starch contents compared with their siblings, indicative of secondary effects. Overexpressing PRK did not increase embryo lipid content, but metabolite profiling suggested that Rubisco activity becomes limiting. Overall, our findings show that the PRK/Rubisco shunt is tightly integrated into the carbon metabolism of green Arabidopsis seeds, and that its manipulation affects seed glycolysis, starch metabolism, and photosynthesis.

Docosahexaenoic acid and phenazine ethosulfate are not efficient lipid modulators for porcine in vitro maturation systems.

The high lipid content in porcine oocytes impairs in vitro embryo production (IVP). Here, we evaluated the influence of two different lipid modulators during in vitro maturation (IVM) on the embryo development and the lipid content of oocytes and embryos. In Experiment I, oocytes were exposed to 50μM docosahexaenoic acid (DHA) with (+) or without (-) the presence of porcine follicular fluid (pFF). In Experiment II, phenazine ethosulfate (PES) was added during IVM at two concentrations (0.5 and 0.05μM). The pFF- with 50μM DHA treatment impaired nuclear maturation, cleavage and blastocyst rates (p < 0.05). Oocytes in pFF- media accumulated less lipids (p < 0.05). The addition of 0.5μM PES reduced all development rates (p < 0.05) and resulted in higher lipid content for oocytes and embryos. Only 0.05μM PES oocytes matured similarly to the control (p > 0.05), although embryo development and embryo lipid content was similar to 0.5μM PES oocytes (p > 0.05). Thus, 50μM DHA supplementation in the IVM medium without pFF impaired oocyte maturation and embryo development rates without interfering in oocyte lipid content even in the presence of pFF. Maturation with PES neither favored porcine embryo development nor reduced their lipid content.

Influence of cAMP modulator supplementation of in vitro culture medium on Bos taurus indicus embryos

The effectiveness of the use of natriuretic peptide C (NPPC) in the blocking of meiosis has already been proven in several species. However, there are no reports on the use of NPPC in the activation of metabolic processes in embryos. Whereas modulations of cAMP concentrations alter the lipid metabolism of bovine oocytes, the present study aims to evaluate the effect of NPPC on the development, lipid content and transcript levels of genes related to lipid metabolism of IVP bovine embryos. For this purpose, ovaries were obtained from a slaughterhouse, and oocytes were fertilized in vitro (D0). From D5 of in vitro culture, embryos were treated with 100 nM NPPC (NPPC group) or with no NPPC (Control group) and evaluated in terms of Blastocyst (D7) and hatching rates (D10). For the assessment of the cytoplasmatic lipid amounts, blastocysts were stained with Sudan Black B dye. The embryonic lipid profile was investigated by electrospray ionization desorption-mass spectrometry (DESI-MS). The abundance of nine transcripts related to lipid metabolism were assessed using the Biomark HD system. For statistical analysis, blastocyst and hatching rates, lipid content by the Sudan Black B and variation of gene expression between groups were compared by Student t-test. For lipid profile analysis, principal component analysis (PCA) and fold-change were performed. The embryo lipid content was similar between NPPC (881 ± 3.7) and Control (883 ± 5.2) groups (p > 0.05). However, cholesteryl esters and TAGs were downregulated by NPPC at multiple levels according to the DESI-MS profiles. Of the analyzed genes, ELOVL6 and SREBF1 showed an up-regulation in the control group (p < 0.05), while CPT2 was observed to be up-regulated in the NPPC-treated embryos. There was no significant difference in the blastocyst production rate between NPPC (44.4%) and Control (42.4%), however the hatching rate at D10 was higher (p < 0.05) in the NPPC group (69.77%) when compared to the Control group (48.33%). These findings demonstrate that NPPC alters the mRNA expression of genes related to lipid metabolism and that it exerts a positive effect on the hatching rates of IVP Bos taurus indicus embryos.

Influence of forskolin supplementation on embryos produced in vitro

The objective of this study was to evaluate the effects of forskolin supplementation of the culture medium on the development, lipid content, and transcript levels genes of in vitro-produced bovine embryos. Ovaries (n = 420) from Nelore cows were obtained from the slaughterhouse. On day 5 (D5) of in vitro culture, the embryos in the experimental group were treated with 10 µM of forskolin, and the control group embryos were not treated. The evaluation was performed based on blastocyst and hatching rates on D7 and D10. For the evaluation of lipid deposition, blastocysts (D7; n = 10/group) were stained with the Sudan black B. Additionally, 47 genes were analyzed with RTq-PCR. The embryo lipid content (gray intensity) was similar (P > 0.05) between the forskolin (772 ± 4.8) and control (883 ± 5.2) groups. The mRNA transcript levels of GPX1, HAND1, POU5F1 and HP1 were increased in the control group (P = 0.06). The mRNA transcript level of SREBF1 was equal (P = 0.06) in both treatments, and those of AKR1, IFNT2 (P = 0.06) and SCD (P = 0.08) were increased in forskolin-derived embryos when compared with control embryos. There was no difference (P > 0.05) in the blastocyst production rate between the forskolin (37.9%) and control (39.5%) groups. Interestingly, the blastocyst hatching rate at D10 was higher (P = 0.09) in the forskolin group (62.9%) than in the control group (48.4%).

Effects of barotrauma and recompression events on subsequent embryo condition of yelloweye rockfish

Catch-and-release fishing may adversely affect reproduction of rockfishes Sebastes spp. due to angling-induced barotrauma. Although yelloweye rockfish (S. ruberrimus) have been shown to be reproductively viable following these events, the energetic cost of recovery may negatively affect reproductive fitness through reduced embryo condition. In this study, female yelloweye rockfish from Prince William Sound, Alaska, were recaptured one to two years following their initial capture and recompression using a deepwater-release mechanism (DRM). Embryo composition from these fish was compared to the embryos from females with no previously known capture history to examine embryo oil globule volume (OGV), energy content, and percent lipid content. Capture history, maternal length and age, and developmental stage explained a high proportion of the variability in embryo OGV, but not energy or percent lipid content. For both groups of females, there were declines in OGV and energy content of embryos from early to late developmental stages. However, there were no differences in OGV and energy content between female groups for each embryo developmental stage and there were no differences in lipid content of embryos for either group between and among developmental stages. These results suggest that embryo condition was similar between females, regardless of capture history. As a result, DRM recompression seems to mitigate the negative effects of barotrauma on yelloweye rockfish embryo composition in subsequent spawning seasons.

Correction: The role of cGMP as a mediator of lipolysis in bovine oocytes and its effects on embryo development and cryopreservation.

[This corrects the article DOI: 10.1371/journal.pone.0191023.].

The role of cGMP as a mediator of lipolysis in bovine oocytes and its effects on embryo development and cryopreservation.

This study aimed to determine the influence of cyclic guanosine 3’5’-monophosphate (cGMP) and cGMP-dependent kinase (PKG) during in vitro maturation (IVM) on lipolysis-related parameters in bovine cumulus-oocyte complexes (COCs), and on embryo development and cryosurvival. COCs were matured with cGMP/PKG modulators and assessed for metaphase II rates (MII), cGMP levels, lipid content in oocytes (OO), transcript abundance for genes involved in lipolysis (ATGL) and lipid droplets (PLIN2) in cumulus cells (CC) and OO, and presence of phosphorylated (active) hormone sensitive lipase (HSLser563) in OO. Embryo development, lipid contents and survival to vitrification were also assessed. Phosphodiesterase 5 inhibition (PDE5; cGMP-hydrolyzing enzyme) with 10-5M sildenafil (SDF) during 24 h IVM increased cGMP in COCs (56.9 vs 9.5 fMol/COC in untreated controls, p<0.05) and did not affect on maturation rate (84.3±6.4% MII). Fetal calf serum (FCS) in IVM medium decreased cGMP in COCs compared to bovine serum albumin (BSA) + SDF (19.6 vs 66.5 fMol/COC, respectively, p<0.05). FCS increased lipid content in OO (40.1 FI, p<0.05) compared to BSA (34.6 FI), while SDF decreased (29.8 and 29.6 FI, with BSA or FCS, respectively p<0.05). PKG inhibitor (KT5823) reversed this effect (38.9 FI, p<0.05). ATGL and PLIN2 transcripts were detected in CC and OO, but were affected by cGMP and PKG only in CC. HSLser563 was detected in OO matured with or without modulators. Reduced lipid content in embryos were observed only when SDF was added during IVM and IVC (27.6 FI) compared to its use in either or none of the culture periods (34.2 FI, p<0.05). Survival to vitrification was unaffected by SDF. In conclusion, cGMP and PKG are involved in lipolysis in OO and possibly in CC and embryos; serum negatively affects this pathway, contributing to lipid accumulation, and cGMP modulation may reduce lipid contents in oocytes and embryos, but without improving embryo cryotolerance.

Modification of mitochondrial function, cytoplasmic lipid content and cryosensitivity of bovine embryos by resveratrol.

Resveratrol is a potent activator of NAD-dependent deacetyltransferase sirtuin-1 (SIRT1) and affects lipid metabolism and ATP generation in somatic cells. In the present study, the effects of supplementing culture medium with resveratrol on lipid metabolism, ATP generation, and cryosensitivity of bovine in vitro produced embryos were investigated. Bovine early cleaved-stage embryos were cultured in medium containing 0 or 0.5 µM resveratrol for 1 or 5 days. Resveratrol treatment for both 1 day and 5 days increased the expression levels of SIRT1 and phosphorylated AMP-activated protein kinase (pAMPK) in the embryos. Furthermore, resveratrol treatment was effective to increase ATP generation and reduce lipid content of the embryos. The effects of resveratrol treatment were diminished by the SIRT1 inhibitor “EX527”, and the reduced lipid content was reversed by treatment with etomoxir (a potent inhibitor of beta-oxidation). Blastocysts developed after resveratrol treatment showed low levels reactive oxygen species and increased cryotolerance. These results demonstrate that resveratrol improves in vitro development of bovine embryos, while reducing cytoplasmic lipid content through activation of beta-oxidation, thereby effective for production of bovine blastocysts with enhanced cryotolerance.

90 LIPID CONTENT OF IN VIVO- AND IN VITRO-PRODUCED JERSEY AND HOLSTEIN CATTLE EMBRYOS AND THE EFFECT OF FORSKOLIN ON EMBRYO LIPID REDUCTION

Jersey embryos have been suggested to have higher lipid content and lower tolerance to cryopreservation. In addition, in vitro-produced (IVP) bovine embryos have darker cytoplasm as a consequence of higher lipid accumulation than in vivo-derived embryos, associated with impaired embryo quality and reduced cryotolerance. Forskolin is an adenylate cyclase activator that regulates cAMP levels in cells and has been shown to induce lipolysis in IVP embryos. We hypothesised that the lipid content of in vivo-produced and IVP Jersey embryos is higher than respective Holstein embryos and that forskolin would reduce lipid content of IVP embryos. The objectives of this experiment were (1) to analyse lipid content of in vivo and IVP Jersey and Holstein cattle embryos and (2) to evaluate the effect of forskolin added to IVP culture media. The factorial experimental design used two breeds (Holstein and Jersey) and three embryo production methods (in vivo, IVP, and IVP + forskolin). IVP embryos (n = 27 blastocysts) were collected from super-stimulated donors by routine procedures 7.5 days after AI. IVP embryos (n = 259 blastocysts) were produced by standard procedures; briefly, oocytes were aspirated from 2- to 8-mm follicles from slaughterhouse ovaries and matured for 24 h in SMM medium (BoviPro, MOFA Global, Verona, WI, USA). Matured oocytes were fertilized using semen from two different bulls for each breed, and embryos were cultured in BBH7 medium (BoviPro, MOFA Global) alone or with the addition of forskolin (10 µM) at Day 5 of culture at 38.5°C in 5% O2, 5% CO2, and 90% N2. The lipid content of embryos was quantified by staining Day 7 blastocysts with 1 μg mL–1 Nile red dye (580–596 nm), after which a digital photograph of the equatorial part of the embryo was taken at 40×, and fluorescence intensity (FI) was measured with Image Pro software. Data (Table 1) were analysed by ANOVA, and means were compared using Tukey’s HSD. Jersey and Holstein IVP embryos had higher lipid content than Holstein in vivo-produced embryos (P &lt; 0.05), but were not different than Jersey in vivo-derived embryos (P &gt; 0.1). Forskolin lowered the lipid content (P &lt; 0.05) of both IVP Jersey and Holstein embryos and was not different (P &gt; 0.1) than in vivo-produced embryos. Addition of forskolin to embryo culture media has the potential to lower embryo lipid accumulation and possibly improve embryo viability and cryotolerance of IVP embryos. Further studies including cryopreservation and transfer of IVP + forskolin embryos to recipients are necessary to corroborate the findings of the present study. Table 1.Fluorescence intensity of in vivo-produced and IVP Jersey and Holstein embryos

168 EFFECT OF CYCLIC ADENOSINE MONOPHOSPHATE MODULATORS DURING OOCYTE IN VITRO MATURATION ON BOVINE EMBRYOS (Gyr×HOLSTEIN) QUALITY

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. Quality determines the oocyte proportion that will develop to blastocyst stage, and although the lipid content is important in oocyte development, a high concentration in embryos is associated with cryotolerance reduction, making this a relevant issue for IVP systems. The in vitro maturation system (IVM) simulated physiological oocyte maturation (SPOM) mimics the physiological maturation events by using cyclic adenosine monophosphate (cAMP) modulators, which promote the increase of oocyte competence. Among the modulators, Forskolin has lipolytic properties. The aim of this study was to evaluate the effect of the SPOM system (Albuz 2010 Hum. Reprod. 25, 12) on bovine embryos (Gyr × Holstein) regarding their total number of cells (TNC) and lipid content. Oocytes were obtained by ovum pick-up from Gyr cows in 5 replications. After selection, they were randomly divided into 2 groups: SPOM (S) and control (C). The IVM lasted 24 h for group C (TCM 199 medium without FBS) in culture oven at 38.5°C, 5% CO2 in atmospheric air and high humidity. In the SPOM system, oocytes were in pre-IVM [TCM 199 medium + 100 µM Forskolin + 500 µM 3-isobutyl-1-methylxanthine (IBMX)] for 2 h and followed for extended IVM (TCM 199 medium + 20 µM cilostamide) for 28 h under the same conditions as control group. After IVM, oocytes were fertilised with semen from a single Holstein bull that was prepared by Percoll gradient method in Fert-TALP medium (Bioklone® Animal Reproduction, São Paulo, Brazil) for 22 h and transfered to culture droplets, where they remained for 7 days (n = 10–13 per group). The lipid content analysis was performed by staining with Oil red and the stained area fraction of each embryo was measured using software ImageJ (NIH, Bethesda, MD, USA). The TNC was measured after being stained with Hoechst 33342 and results were analysed by Student's t-test in Instat GraphPad program, with a 5% significance level. There was no significant difference (P &gt; 0.05) between embryos from both groups on TNC (group S: 88.9 ± 28.0A; group C: 101.6 ± 29.1a) and lipid content (group S: 0.93 ± 12:18A; group C: ±0.15 to 0.96) analysis. Some studies have shown there is a beneficial effect on embryo quality when using this system; however, our results demonstrated that there was no effect on total number of cells using our conditions. Some authors have also demonstrated a reduction in embryo lipid content using Forskolin during in vitro culture. Our results suggest that the time of Forskolin exposure was not enough to ensure lipolytic action on the structures produced from oocytes (Gyr) treated in pre-IVM. It was concluded that the SPOM system had no effect on TNC and lipid content of Gyr/Holstein embryos. Financial support from FAPERJ and CAPES is acknowledged.

165 CRYOPRESERVATION OF IN VITRO PRODUCED BOVINE EMBRYOS AFTER LIPID DECREASE WITH FORSKOLIN

Forskolin® (F-6886) is being used to induce lipolysis and increase cryotolerance, to be an activator of adenylate cyclase, and elevating the cyclic adenosine monophosphate (cAMP) levels. The objective of this experiment was to induce the chemical lipolysis of embryos to improve vitrification and the hypothesis would be that Forskolin decrease the amount of lipid droplets, improve the production of blastocysts, and increase the survival rate after vitrification and warming. Eight random effect were performed which oocytes (N = 1172) were matured in TCM 199® supplemented with 10% of fetal bovine serum (FBS), under 5% CO2 atmosphere, at a temperature of 38.5°C and absolute humidity for 24 h. Semen was selected by Percoll gradient with a final concentration of the 2 × 106 sperm mL–1. Presumptive zygotes were cultured in SOFaa and 2.5% of FBS and were kept in an incubator with 5% CO2, 5% O2 and 90% N2 at 38.5°C and absolute humidity until Day 6, when Forskolin was added and remained until Day 7; control (group without Forskolin); F 2.5 µM (group with 2.5 µM Forskolin); F 5 µM (group with 5 µM Forskolin). On Day 7 (Day 0 = IVF) the rate of blastocyst formation was observed then they were vitrified. Apoptosis was analysed using the TUNEL technique, and the lipid content analysis was performed with Sudan Black B® (S-0395). To estimate the lipid content of embryos, 1 photo at a blastocyst group was performed and submitted to the program ImageJ 1.14 (Wayne Rasband, National Institutes of Health, Bethesda, MD, USA). The embryos were limited to obtain the area (μm2), and gray intensity mean (arbitrary units), and gray intensity per area was calculated (arbitrary units/μm2). Data were analysed by ANOVA with PROC GLM of SAS (SAS Institute, Cary, NC, USA). Sources of variation in the model including treatment and replicas were regarded as fixed and random effects, respectively. Data are presented as mean and standard least-squares error. For all analyzes was adopted the significance level of 5%. There was no difference in blastocyst rate: control (37.0 ± 4.0%), F 2.5 μM (38.6 ± 4.0%), F 5 μM (40.7 ± 4.0%). There were difference in lipids content between all groups: control (136.8 ± 2.2ab); F 2.5 μM (128.5 ± 2.2b), F 5 μM (135.6 ± 2.3c; P &lt; 0.05). The F 2.5 μM group showed the higher rate of apoptotic cells compared to other groups: control (12.1 ± 3.5%a), F 2.5 μM (16.7 ± 4.1%b), F 5 μM (11.1 ± 6.5%a; P &lt; 0.05). After vitrification, there was no difference in re-expansion: control (71.3 ± 8.9%), F 2.5 μM (73.1 ± 8.9%); F 5 μM (66.1 ± 8.9%) and apoptosis rate: control (22.3 ± 3.1%); F 2.5 μM (37.3 ± 3.8%); F 5 μM (33.2 ± 6.5%) between the groups. The Forskolin was effective at lower concentration to diminish lipids concentrations in embryos. But when we analysed the apoptotic cell, the lower concentration of Forskolin damaged embryos, but this effect could be diminished after vitrification and warming, when the drug did not increase the apoptotic cells. However, we need to study other concentrations of Forskolin. FAPESP (2010/50410–2/2014/21289–1) is acknowledged for support.

89 EFFECT OF MEDIA, METABOLIC REGULATORS, AND STAGE OF DEVELOPMENT ON LIPID CONTENT AND MITOCHONDRIAL POLARITY OF IN VITRO-PRODUCED HOLSTEIN EMBRYOS

Current bovine embryo culture methods result in accumulation of lipids and reactive oxygen species, possibly due to sub-optimal metabolic regulation. These effects decrease the cryopreservation survival and implantation potential of in vitro-produced (IVP) embryos. Forskolin has been shown to decrease lipid accumulation, and vitamin K2 (Vit K2) is thought to decrease oxidative stress from in vitro conditions. The aims of this study were (1) to assess lipid content of embryos cultured with or without forskolin and Vit K2 in both continuous and sequential SOF-based medium, and (2) to examine individual and combined effects of forskolin and Vit K2 on mitochondrial polarity. For Experiment 1, a 2 × 2 × 2 factorial design was used to compare culture systems (continuous v. 3-step sequential), additives (no additive v. Vit K2 (0.5 mM at Day 3) plus forskolin (10 µM at Day 5), and blastocyst stage [6 (early) v. 7 (late)] on overall lipid content. For Experiment 2, mitochondrial polarity of stage 7 blastocysts was analysed from the following groups: no additive, Vit K2 (0.5 mM at Day 3), forskolin (10 µM at Day 5), and Vit K2 plus forskolin. IVP embryos (n = 199, Experiment 1; n = 45, Experiment 2) were produced by standard procedures and cultured at 38.5°C in 5% O2, 5% CO2, and 90% N2. For Experiment 1, embryos were stained with 1 μg mL–1 Nile Red, and two images per embryo were taken along the equatorial plane at 40× magnification. For Experiment 2, embryos were stained with 300 nM MitoTracker Red CMX-Rosamine, and 10 images per embryo were acquired by confocal microscopy with a 5-μm step size at 40× magnification. For both experiments, fluorescence intensity (FI) of each image was measured by Image PRO software with embryo controlled for and background fluorescence corrected. Data (Table 1) were analysed by ANOVA and means were compared by Tukey’s HSD. In Experiment 1, embryos cultured with forskolin and Vit K2 showed decreased lipid content in both the early and late stage (P &lt; 0.05), with no effect from culture system (P &gt; 0.05). In Experiment 2, forskolin and Vit K2 individually increased mitochondrial polarity (P &lt; 0.05), but had no combined effect (P &gt; 0.05). In conclusion, these data suggest that while a combination of forskolin and Vit K2 as media additives reduces lipid accumulation, the interaction between these metabolic regulators may negate their individual effects on mitochondrial polarity. Table 1.Fluorescence intensity of Nile Red and MitoTracker Red dyes between treatment groups

Genetic influence on the reduction in bovine embryo lipid content by l-carnitine.

The decreased rate of pregnancy obtained in cattle using frozen in vitro embryos compared with in vivo embryos has been associated with over-accumulation of intracellular lipid, which causes cell damage during cryopreservation. It is believed that the higher lipid content of blastomeres of bovine embryos produced in vitro results in darker-coloured cytoplasm, which could be a consequence of impaired mitochondrial function. In this study, l-carnitine was used as a treatment to reduce embryonic lipid content by increasing metabolism in cultured bovine embryos. We have observed previously that in vivo embryos of different dairy breeds collected from cows housed and fed under the same conditions differed in lipid content and metabolism. As such, breed effects between Holstein and Jersey were also examined in terms of general appearance, lipid composition, mitochondrial activity and gene expression. Adding l-carnitine to the embryo culture medium reduced the lipid content in both breeds due to increased mitochondrial activity. The response to l-carnitine was weaker in Jersey than in Holstein embryos. Our results thus show that genetics influence the response of bovine embryos to stimulation of mitochondrial metabolism.

53 EFFECT OF ADDITION OF L-CARNITINE AND CONJUGATED LINOLEIC ACID DURING BOVINE EMBRYO CULTURE ON CRYOSURVIVAL, LIPID CONTENT, AND GENE EXPRESSION

The objective was to determine the effects of addition of l-carnitine (LC) and trans-10, cis-12 conjugated linoleic acid (CLA) during bovine embryo culture on cryosurvival, lipid content, and gene expression. For all experiments, embryos were produced in vitro using abattoir-derived oocytes. Following insemination, presumptive zygotes were randomly assigned in a 2 × 2 factorial to be cultured in SOF-BE1 supplemented with or without 3.03 mM LC and 100 μM CLA until Day 7. For Exp. 1, blastocyst- and expanded-blastocyst-stage embryos (n = 777) were slow-frozen in 1.5 M ethylene glycol. Embryos were thawed and then cultured for 72 h. Re-expansion and hatching rates were recorded at 24, 48, and 72 h. There was no effect of LC on post-thaw re-expansion rates, but CLA reduced (P &lt; 0.05) and tended (P &lt; 0.08) to reduce re-expansion rate at 24 and 48 h, respectively (76.5 ± 2.5 v. 70.4 ± 2.5 and 79.5 ± 2.2 v. 76.0 ± 2.2, respectively). Whereas hatching rate at 72 h tended (P &lt; 0.08) to be higher for embryos cultured with LC (67.8 ± 2.5 v. 74.4 ± 2.5), treatment with CLA reduced (P &lt; 0.05) hatching rate at 48 h (62.3 ± 2.6 v. 54.9 ± 2.6). In Exp. 2, to determine lipid content, expanded blastocyst-stage embryos (n = 263) were harvested and stained using Nile Red. Embryos were examined for fluorescence using an epifluorescence microscope, and intensity of fluorescence per unit area was quantified using ImageJ software (NIH, Bethesda, MD, USA). There was a significant interaction (P &lt; 0.01) between LC and CLA affecting embryo lipid content. Whereas addition of CLA during culture increased lipid, treatment with LC and the combination of LC and CLA reduced lipid (22.8 ± 1.1 v. 19.1 ± 1.1 v. 28.4 ± 1.1 v. 19.2 ± 1.2 for no additive, +LC, +CLA, and +LC and CLA, respectively). For Exp. 3, the effect of LC and CLA on the relative abundance of genes involved in lipid metabolism (ELOVL6, SCD1, SQLE, HMGCS1, CYP51A1, FDPS, FDFT1, LDLR, and SC4MOL) was determined. Pools of 5 expanded blastocyst-stage embryos from each treatment were collected across 5 replicates. The RNA was purified and synthesised into cDNA for RT-qPCR analysis. The SDHA, GAPDH, and YWAZ were used as housekeeping genes. Addition of LC during culture reduced (P &lt; 0.05) the abundance of 4 of the 9 genes analysed (SQLE, HMGCS1, CYP51A1, and FDPS) and tended (P &lt; 0.08) to reduce a fifth (FDFT1). In addition, there was a tendency (P &lt; 0.08) for LC to increase the abundance of SCD1. Addition of CLA during culture had minimal effects on transcript abundance. In particular, CLA treatment reduced (P &lt; 0.01) ELOVL6 and tended (P &lt; 0.08) to increase SCD1. In contrast to previous studies, post-thaw cryosurvival was not significantly improved by treatment with LC or CLA. Results indicate that reduced embryo lipid content caused by LC treatment is due, in part, to an alteration in the abundance of genes involved in lipid metabolism. Further research is still necessary to determine whether in vivo survival following transfer of cryopreserved embryos can be enhanced by treatment with LC or CLA.Support was provided by USDA AFRI Grant 2010–85122–20623.

49 EFFECTS OF DIETARY CONJUGATED LINOLEIC ACID SUPPLEMENTATION ON BOVINE OOCYTE LIPID METABOLISM, LIPID COMPOSITION, AND EMBRYO CRYOTOLERANCE

Reduced tolerance to chilling and cryotolerance of oocytes and embryos has been associated with greater cytoplasmic lipids. Previous studies in the cow have demonstrated nutrition-induced modification of follicular components. trans-10, cis-12 conjugated linoleic acid (CLA) was identified as a potent inhibitor of milk fat synthesis in lactating cows, and inclusion of CLA in bovine embryo culture medium reduced embryo lipid content and improved post-thaw embryo survival. Dietary supplementation of cows with CLA could alter oocyte fatty acid metabolism, oocyte lipid composition, and embryo cryotolerance, and responses may be different between Bos indicus and Bos taurus cattle. Therefore, a series of experiments were conducted to evaluate effects of dietary CLA on bovine oocyte lipid content and lipid metabolism and cryosurvival of in vitro-produced embryos from CLA-supplemented oocyte donor cows. Lactating Holstein cows (n = 39) were supplemented 100 g per head/d CLA or Ca salts of palm oil to determine effects of dietary CLA on milk production and milk composition. Nonlactating Holstein (n = 8) and Brahman (n = 17) cows were individually supplemented with 150 g per head/d CLA or no lipid supplement. Cumulus-oocyte complexes (COC) were collected after 41 ± 1 day of CLA supplementation, and mRNA was isolated for qPCR. Relative gene expression in COC from CLA- and control-fed cows was evaluated for genes involved in lipid metabolism (CPT1, FADS2, and PPARα). Crossbred (Angus × Red Angus × Brangus) cows (n = 28) were randomly allotted to a 2 × 2 factorial experiment and fed 150 g per head/d CLA or no lipid supplement. Oocytes were collected (Day 129 and 143 of CLA supplementation), matured, fertilized, and cultured in vitro for 7 days in serum-free culture medium. Embryos were cryopreserved in individual 0.25-mL plastic straws containing 1.5 M ethylene glycol using a slow-cooled method. Post-thaw survival and hatching were evaluated using a 24-h in vitro culture (mSOF with 5% FBS) assay. Milk yield, milk composition, and Nile Red intensity were analysed using the GLM procedure of SAS (SAS Institute Inc., Cary, NC, USA). Follicle and oocyte responses were analysed with the Mixed procedure of SAS. Relative gene expression of COC was evaluated using the REST 2009 Software. In vitro embryo production, post-thaw survival, and hatching rates were analysed using Chi Square. Milk fat was depressed (P &lt; 0.001) by 10.1% in lactating Holstein cows fed CLA. Dietary supplementation of Holstien and Brahman cows with CLA did not alter expression of genes (CPT1, FADS2, and PPARα) in COC. Dietary supplementation of crossbred cows with CLA before oocyte collection did not influence cryotolerance of in vitro-produced embryos. Lipid content of oocytes (measured by Nile Red florescence) and follicle, oocyte, and embryo production was not influenced by CLA supplementation of Holstein and Brahman cows. The highly regulated mechanisms involved in fatty acid uptake by ovarian components may help explain the lack of ovarian response to dietary CLA in the current study.

The effects of conjugated linoleic acid isomers cis-9,trans-11 and trans-10,cis-12 on in vitro bovine embryo production and cryopreservation

Conjugated linoleic acid (CLA) isomers can affect the lipid profile and signaling of cells and thereby alter their function. A total of 5,700 bovine oocytes were used in a structured series of experiments to test the effects of CLA cis-9,trans-11 and CLA trans-10,cis-12 in vitro. In experiment 1, high doses of each CLA isomer during in vitro maturation (IVM) were compared with high or low doses during the entire in vitro culture (IVC) of parthenogenetic embryos. High doses of the CLA isomers ranged from 50 to 200μM and low doses were 15 and 25μM. In experiment 2, the low doses of each CLA isomer were tested during IVM/IVC on embryos produced by in vitro fertilization (IVF). Experiment 3 compared the effects of 15μM doses of each CLA isomer during IVM or IVC of IVF embryos. In experiment 4, post-rewarming survival rates and blastomere counts were assessed for embryos supplemented with each CLA isomer during IVM or for 36h before vitrification. In experiment 1, when either CLA isomer was provided only during IVM, we observed no effects on overall rates of maturation, cleavage, or blastocysts (92.2±1.6%, 78.3±4.1%, and 28.9±5.1%, respectively). However, high doses of each CLA isomer, but not low doses, during the entire embryo culture period decreased blastocyst rates (5–20%) in a dose-dependent manner. Cleavage rates improved with 15 or 50μM CLA trans-10,cis-12. Progesterone concentrations in maturation media were significantly increased by high doses of each CLA isomer compared with control, but low doses of CLA isomers had no effect. In experiment 2 with IVF embryos, low doses of each CLA isomer did not alter cleavage rates (average 84.9±1.9%) and only 25μM CLA trans-10,cis-12 during IVC reduced blastocyst rates below those of controls (25.5±2.1 vs. 38.2±2.3%). The lipid content of embryos was increased and relative expression of the BIRC5 (baculoviral IAP repeat containing 5) gene was depressed by CLA trans-10,cis-12. In experiment 3, low doses (15μM) of each CLA isomer during IVC significantly reduced blastocyst rates (20.6±2.4% and 27.7±1.2% vs. 34.18±1.2% for CLA trans-10,cis-12 and CLA cis-9,trans-11 compared with control, respectively) with less effect of each CLA during IVM. In experiment 4, adding 100μM CLA cis-9,trans-11 during the final 36h of culture resulted in a high survival rate after rewarming and culture, and the higher embryo blastomere count was comparable to that of control embryos not undergoing vitrification. In conclusion, supplementation with either CLA isomer did not improve embryo production, but inclusion of CLA cis-9,trans-11 before vitrification improved the quality of bovine IVF embryos after rewarming and culture.

Birth of Kittens After the Transfer of Frozen–Thawed Embryos Produced by Intracytoplasmic Sperm Injection with Spermatozoa Collected from Cryopreserved Testicular Tissue

The aim of this study is to produce live kittens from oocytes fertilized by intracytoplasmic sperm injection (ICSI) with frozen/thawed testicular spermatozoa. Spermatozoa were collected from thawed testicular tissue and subsequently injected into in vitro matured cat oocytes. At 24 h post-ICSI, presumptive zygotes/cleaved embryos were treated with 10 μm forskolin for 24 h to reduce intracellular lipid content of embryos (delipidation). At 48 h after oocyte injection, cleaved embryos (2- to 8-cell stage) were frozen in 10% (v/v) ethylene glycol-based medium by a slow controlled rate method and stored in liquid nitrogen. To evaluate in vitro and in vivo developmental competence, frozen embryos were thawed and then cultured for 6 days (n = 155) or cultured for 2 h before transferred (n = 209) to hormonal (equine chorionic gonadotropin/hCG)-treated cat recipients. Cleavage frequency at day 2 after ICSI with frozen/thawed testicular spermatozoa was ~30%. The percentages of frozen/thawed embryos that developed to morula and blastocyst stage (on day 3 and day 6 of in vitro culture, respectively) were significantly lower than that of fresh ICSI embryos (22.6 vs 45.2% and 21.3 vs 38.7%, respectively; p < 0.05). However, no difference was found in the number of blastomeres between frozen/thawed (242.5 ± 43.1) and fresh (320.2 ± 28.1) blastocysts. Three of seven cat recipients were pregnant and one pregnant cat delivered two healthy kittens. This is the first report of the birth of kittens after the transfer of frozen-thawed embryos produced by ICSI with frozen/thawed testicular sperm.

Supplementation of culture medium with L-carnitine improves development and cryotolerance of bovine embryos produced in vitro

High lipid content in embryos is associated with low freezing tolerance. This study assessed the effects of exogenous L-carnitine, an enhancer of lipid metabolism, on the in vitro development and freezing survival of bovine embryos. Also, effects on metabolic activity, reactive oxygen species (ROS) and apoptosis were investigated. Supplementation of embryo culture medium with 1.518 mM or 3.030 mM L-carnitine significantly increased the rates of zygote development to the blastocyst stage and blastocyst cell numbers whereas 6.072 mM of this compound did not improve embryo development. Survival rates after slow freezing of blastocysts were significantly higher when embryos were cultured in the presence of 1.518 mM or 3.030 mM L-carnitine compared with the control. A lower density of lipid droplets was detected in L-carnitine-treated blastocysts compared with the control. L-carnitine significantly reduced ROS levels in 2-cell embryos but did not reduce ROS levels at later stages. The apoptotic cell rate was not different between control and L-carnitine-treated blastocysts. L-carnitine significantly increased ATP levels in 2-cell embryos but not at the 8-cell or blastocyst stages. L-carnitine increased the expression of metabolism-related ATP6 and COX1 genes in blastocysts. In conclusion, L-carnitine supplementation enhanced lipid metabolism in embryos resulting in improved development and cryotolerance of bovine blastocysts produced in vitro.

92 UTILISATION OF ENDOGENOUS FATTY ACID STORES FOR ENERGY PRODUCTION IN BOVINE PRE-IMPLANTATION EMBRYOS

Current embryo culture media are based on the carbohydrate metabolism of embryos. However, little is known about the metabolism of endogenous lipids. This is surprising given the high intracellular lipid densities of embryos of some species and the potential for ATP production via β-oxidation. L-carnitine is a β-oxidation co-factor that is absent in most culture media. The aim of this study is to investigate the influence of carnitine supplementation ± carbohydrates on bovine embryo development. Abattoir-derived cattle cumulus–oocyte complexes were cultured and fertilised (Sutton-McDowall et al. 2006 Biol. Reprod. 74, 881–888). Post-fertilisation (24 h), presumptive zygotes were transferred into an amino acid-free cleavage media ± carbohydrates (glucose, lactate and pyruvate) ±5 mM carnitine and cultured for 4 days. The absence of carbohydrates during culture resulted in embryos arresting at the 2- and 4-cell stages. Remarkably, +carnitine significantly increased development to the morula stage compared with +carbohydrates alone (20.4 ± 3% vs 4.7 ± 2.5% morula development; P &lt; 0.001). The combination of carbohydrates and carnitine supplementation further improved embryo development, with 14-fold more embryos reaching the morula stage after culture in the +carbohydrates +carnitine group compared with the +carbohydrates group (+carbohydrates = 3.1 ± 1.9 vs +carbohydrates +carnitine = 43.8 ± 9.1% morula development; P &lt; 0.05). The beneficial effects of carnitine supplementation on embryo development were reversed when embryos were cultured in presence of etomoxir, a non-reversible inhibitor of the rate-limiting enzyme of β-oxidation (development to 8-cell stage; +carnitine = 33.9 ± 8% vs +carnitine +etomoxir = 19.2 ± 4.9%; P &lt; 0.05). Intracellular lipid content of embryos +carnitine was determined by culturing presumptive zygotes in media -carbohydrates ± carnitine for 24 h. Lipid content of embryos was determined by measuring BODIPY 493/503 dye fluorescence. Carnitine supplementation reduced fluorescence intensity 1.8-fold (P &lt; 0.001). Adenosine triphosphate and ATP:ADP levels were measured in embryos after 24 h of culture ± carbohydrates ± carnitine. While there was a trend for +carnitine to increase ATP levels (P = 0.09), ADP levels were higher and ATP:ADP ratio were 1.9-fold lower (main effect, P &lt; 0.05) compared with embryos cultured in –carnitine. This indicates +carnitine embryos were more metabolically active, with higher rates of ATP-ADP conversion. We have shown carnitine supplementation supports pre-compaction embryo development and there is an additive effect of +carnitine +carbohydrate on early embryo development. This is most likely through increased β-oxidation levels within embryos. Current disparities between in vivo and in vitro embryo production, in particular increased lipid content (Romek et al. 2010 Theriogenology 74, 265–276) and decreased developmental potential of in vitro-produced embryos, may be an artefact resulting from limited lipid oxidation in vitro.