Invivo-derived Embryos Research Articles

Effect of cryopreservation on Odc1 and RhoA genes expression in diapausing mouse blastocysts.

The possibility of embryo cryopreservation is important for applying the genome resource banking (GRB) concept to those mammalian species that exhibit embryonal diapause in their early development. Odc1 encodes ODC1, which is a key enzyme in polyamine synthesis. RhoA is an essential part of Rho/ROCK system. Both Odc1 and RhoA play an important role in preimplantation embryo development. Studying these systems in mammalian species with obligate or experimentally designed embryonic diapause may provide insight into the molecular machinery underlying embryo dormancy and re-activation. The effect of cryopreservation procedures on the expression of the Odc1 and RhoA in diapausing embryos has not been properly studied yet. The purpose of this work is to address the possibility of cryopreservation diapausing embryos and to estimate the expression of the Odc1 and RhoA genes in diapausing and non-diapausing embryos before and after freeze-thaw procedures using ovariectomized progesterone treated mice as a model. Both diapausing and non-diapausing invivo-derived embryos continued their development invitro after freezing-thawing as evidenced by blastocoel re-expansion. Although cryopreservation dramatically decreased the expression of the Odc1 and RhoA genes in non-diapausing embryos, no such effects have been observed in diapausing embryos where these genes were already at the low level before freeze-thaw procedures. Future studies may attempt to facilitate the re-activation of diapausing embryos, for example frozen-thawed ones, specifically targeting Odc1 or Rho/ROCK system.

Evaluation of bovine embryo quality based on gene expression profiling using whole-transcriptome amplification.

This study aimed to develop a method to evaluate the quality of bovine in vitro fertilized (IVF) embryos based on gene expression profiling via whole-transcriptome amplification. The expression of 11 developmentally important genes in individual bovine in vivo-derived (IVD) and IVF embryos were examined. Gene expression profiling was conducted by classifying the expression level of each gene in individual embryos as low, medium, or high. The IVF group had a higher (P < 0.01) proportion of embryos with low expression of SOX2, NANOG, and FGF4. In addition, a correlation analysis between the expression levels of each gene in individual embryos demonstrated that the relationship between gene expression differed with respect to IVD and IVF embryos. Our results suggest that the expression profiling of developmentally important genes using IVD embryos as normal controls could be a useful indicator for evaluating the quality of bovine IVF embryos.

In vitro-produced equine blastocysts exhibit dispersed ICM cell allocation

Although in vitro production (IVP) of horse embryos has increased markedly in clinical practice, pregnancy rates after transfer are lower, and the incidence of pregnancy loss and monozygotic twins, higher than for in vivo-derived (IVD) embryos. Cell lineage specification is critical to normal early embryo development, and starts with differentiation of trophectoderm (TE) from inner cell mass (ICM) cells, followed by division of the ICM into primitive endoderm (PE) and epiblast (EPI). We examined the influence of developmental stage and speed, IVP and culture (in vivo versus in vitro) on expression of markers for the 3 early cell lineages, namely CDX-2 (TE), GATA-6 (PE) and SOX-2 (EPI). Day 7 IVD blastocysts (n=3 early; n=3 expanded), and IVP embryos identified as blastocysts on day 7 (n=5) or day 9 (n=9) were examined using confocal microscopy to compare total cell number, proportions and distribution of cells expressing CDX-2, GATA-6 and SOX-2. Additional day 7 IVP blastocysts were cultured for 2 days, either in vitro (n=5) or in vivo (after transfer into recipient mares; n=3), to examine the impact on subsequent development. Numerical data were analyzed using T- or Mann-Whitney U-tests. In IVD embryos, CDX-2 expression was exclusive to the TE, whereas SOX-2 expression was detected in both ICM and TE cells in early blastocysts but only thepresumed EPI in expanded blastocysts. GATA-6 was co-expressed with SOX-2 in outer ICM cells in early blastocysts but specific to PE cells lining the EPI and TE in expanded blastocysts. In IVP blastocysts, CDX-2 was also specific to the TE. However, SOX-2 and GATA-6 positive cells were intermingled in the ICM, and both SOX-2 and GATA-6 were co-expressed in TE cells. Strikingly, the EPI cells of IVP blastocysts were more dispersed, with larger mean inter-EPI cell distances (day 7 blastocysts, 52±6µm; day 9, 68±9µm), than in IVD embryos (35±3µm). Total cell number was higher in day 7 IVD (486±81) than IVP (day 7, 317±21; day 9, 377±104) blastocysts, but proportions of the different lineages didn't differ. Cell distribution in day 7 IVP embryos didn't change during an extra 2-day in vitro culture whereas, after 2 days in a mare's uterus, the SOX-2 (EPI) cells had aggregated and compacted, and segregated from PE cells. Overall, with respect to cell lineage allocation, IVP embryos resemble early IVD blastocysts in co-expressing SOX-2 and GATA-6 in TE cells, but differ by having a more dispersed ICM/EPI. While the EPI cells do compact following transfer to a recipient mare, the initial dispersal might contribute to both lower developmental competence (inadequate EPI aggregation) and a higher incidence of monozygotic twins (separated EPIs).

145 Specific Gravity as an Assessment of Embryonic Viability to Improve Implantation Rates for in Vitro Produced and in Vivo Derived Bovine Embryos

Abstract The objective of this study was to evaluate the ability of a specific gravity chamber (SGC) to identify embryos most likely to result in successful implantation following embryo transfer. In this study, 19 in vitro produced (IVP) and 15 in vivo derived (IVD) Grade bovine embryos were allowed to descend through media in an SGC. Descent time through a 1-cm timing region was recorded, and embryos were retrieved from the chamber and transferred into recipient females or cryopreserved and transferred at a later date. To determine if chamber evaluation had an effect on pregnancy status, 27 IVP and 12 IVD embryos that were not evaluated with the SGC were also transferred alongside project embryos. Pregnancy was determined via transrectal ultrasound palpation and recorded. There was no significant difference in conception rates between embryos evaluated with the SGC and those not, indicating that chamber analysis had no negative impact on viability of both IVP (P = 0.54) and IVD (P = 0.93) embryos. Twenty-two of the 34 total project embryos resulted in successful implantation and pregnancy, with 13 pregnancies (68.4%) by IVP and 9 (60%) by IVD. There was no difference in average descent time of pregnant and non-pregnant embryos for IVP (P = 0.54) or IVD embryos (P = 0.24). When divided into groups according to descent time, 32% of all observations for IVP embryos occurred between 30 to 50 seconds with a 66.7% conception rate, and 42% occurred between 70 to 90 seconds with a 75% conception rate (P = 0.85). For IVD, 60% of all observations occurred between 90 to10 seconds, with a conception rate of 66.7% (P = 0.35). Though not significant, the numeric trends highlighted in these data lend support to previous research utilizing specific gravity. Further research is needed to thoroughly evaluate the potential of this technology as a method of noninvasive assessment of embryo viability.

Preimplantation Genetic Testing for Aneuploidy (PGT-A) Reveals High Levels of Chromosomal Errors in In Vivo-Derived Pig Embryos, with an Increased Incidence When Produced In Vitro.

Preimplantation genetic testing for aneuploidy (PGT-A) is widespread, but controversial, in humans and improves pregnancy and live birth rates in cattle. In pigs, it presents a possible solution to improve in vitro embryo production (IVP), however, the incidence and origin of chromosomal errors remains under-explored. To address this, we used single nucleotide polymorphism (SNP)-based PGT-A algorithms in 101 in vivo-derived (IVD) and 64 IVP porcine embryos. More errors were observed in IVP vs. IVD blastocysts (79.7% vs. 13.6% p < 0.001). In IVD embryos, fewer errors were found at blastocyst stage compared to cleavage (4-cell) stage (13.6% vs. 40%, p = 0.056). One androgenetic and two parthenogenetic embryos were also identified. Triploidy was the most common error in IVD embryos (15.8%), but only observed at cleavage, not blastocyst stage, followed by whole chromosome aneuploidy (9.9%). In IVP blastocysts, 32.8% were parthenogenetic, 25.0% (hypo-)triploid, 12.5% aneuploid, and 9.4% haploid. Parthenogenetic blastocysts arose from just three out of ten sows, suggesting a possible donor effect. The high incidence of chromosomal abnormalities in general, but in IVP embryos in particular, suggests an explanation for the low success of porcine IVP. The approaches described provide a means of monitoring technical improvements and suggest future application of PGT-A might improve embryo transfer success.

IETS management of the challenges associated with embryo pathogen interaction

One of the very first challenges the International Embryo Transfer Society (IETS) addressed was concern about disease transmission via the transfer of in vivo–derived (IVD) bovine embryos. IETS commissioned its Import/Export Committee, later named Health and Safety Advisory Committee (HASAC), to resolve this matter, with the assistance of the Data Retrieval Committee following its formation in 1991. Since its first meeting in 1984, considerable achievements have been made, including meeting the numerous challenges created by the many innovations in this industry. Based on research studies and their designs, the IETS HASAC developed a system for categorising pathogens and diseases potentially susceptible to interaction with IVD embryos. This has been instrumental in defining safe operating protocols and ultimately leading to the development of the now universally accepted techniques for certification of embryo health. The close cooperation of IETS/HASAC with the World Organization of Animal Health (WOAH, formerly OIE) has facilitated the establishment of guidelines for regulators worldwide, thus ensuring the safety of international trade with embryos, while avoiding unjustified regulatory measures. In addition, IETS/HASAC produced and published the IETS Manual: A Procedural Guide and General Information for the Use of Embryo Transfer Technology Emphasising Sanitary Procedures for the embryo transfer industry (1st edition, 1987; 5th edition, 2023). This manual and its updates were designed to provide the industry world-wide with a source of information on safe and sanitary handling procedures for embryos, to describe the procedures necessary to ensure that the transfer of embryos does not result in transmission of pathogenic agents or disease, and to ensure consistent and accurate identification of embryos. The result of these 40 years of IETS/HASAC involvement is that embryo transfer technology is recognised as having a comparative advantage in international movement of germplasm.

Vitrification and in-straw warming do not affect pregnancy rates of biopsied bovine embryos

In the cattle industry, in vivo or in vitro embryo production combined with genotyping and cryopreservation technologies allows the selection and conservation of embryos carrying genes for desirable traits. This study aimed to assess the efficiency of a vitrification method suitable for in-straw warming of biopsied in vivo derived (IVD) bovine embryos. Three experiments were carried out using two methodologies: the Cryotop®, the gold standard vitrification and 3-step warming methodology, or the VitTrans, a vitrification/in-straw 1-step warming method that enables direct embryo transfer to the uterus. In experiment 1, intact and biopsied in vitro produced (IVP) day 7 expanded blastocysts were vitrified using the Cryotop® and warmed in 1- or 3-steps. No differences in survival rates were recorded at 24 h after warming for intact or biopsied IVP blastocysts irrespective of the warming procedure. In experiment 2, the effect of the time from trophectoderm (TE) biopsy to vitrification/in-straw warming on post-warming survival rate was assessed. No significant differences in survival were observed when blastocysts were vitrified/in-straw warmed immediately after biopsy or after 3 h in culture when compared to intact blastocysts. In experiment 3, IVD embryos were vitrified 3 h after biopsy using the Cryotop® or the VitTrans method and pregnancy rates were assessed at day 60 after transfer. Fresh, biopsied embryos served as control. Similar pregnancy rates were observed when IVD biopsied embryos were transferred fresh or vitrified/warmed by the Cryotop® or VitTrans method. No significant effect of the embryo quality or developmental stage was detected on the percentage of pregnant recipients when IVD biopsied embryos were transferred fresh or after vitrification. While fresh female IVD embryos produced significantly higher pregnancy rates than male embryos, there were no differences in pregnancy rates when male or female vitrified/warmed embryos were transferred. About 81% from the biopsies analyzed successfully determined the embryo sex, confirming that DNA was there, and it was efficiently amplified. To conclude, our findings indicate that both vitrification methodologies produced similar post-warming outcomes for both intact and biopsied IVP embryos. Besides, vitrification/in-straw warming of biopsied IVD bovine embryos did not affect the viability to originate pregnancy, being a useful option for their direct transfer in field conditions.

4 Aryl hydrocarbon receptor targets are upregulated in porcine blastocyst-stage embryos that were cultured invitro: A transcriptional analysis

Invitro-produced (IVP) porcine embryos are developmentally delayed compared with those derived invivo. Thus, efforts have been made to modify the current medium for IVP of porcine embryos in an attempt to shift the abundance of target transcripts towards the invivo level. The objective of the current study was to identify differences in mRNA abundance that may account for reduced developmental competence in IVP embryos and to determine whether alterations to maturation and culture media directed the transcriptional profiles of IVP embryos towards an invivo state. Following AI of gilts, an oviduct and tip of the uterine horn were flushed on Day 2 to recover 4-cell stage embryos; these were cultured for 4 days in MU3, generating IVM and invitro-cultured (IVC) blastocyst-stage embryos. On Day 6, the gilts were killed, and the contralateral horns were flushed to obtain invivo-derived (IVV) blastocyst-stage embryos. The third group of blastocyst-stage embryos, referred to as invitro-matured and cultured (IVMC), were created by aspirating cumulus–oocyte complexes from slaughterhouse-derived ovaries, maturing and fertilizing invitro, and culturing for 6 days in MU3. Total RNA was extracted from pools of 10 blastocyst-stage embryos with 3 replicates per group. First- and second-strand cDNA was synthesised and sequenced by using the Illumina platform (Illumina Inc.). After removal of adapters and reads that mapped to porcine rRNA genes and the PhiX genome, reads were mapped to the Sus scrofa genome by using STAR (version 2.7.1a) with default options. Pairwise comparisons were performed to test for differential expression of genes by using the Bioconductor package DESEqn 2. Transcripts were differentially abundant (false discovery rate &amp;lt;0.05) between IVV and IVC embryos (2,450), between IVV and IVMC embryos (3,045), and between IVC and IVMC embryos (262). Pathways related to cell cycle were downregulated in IVC and IVMC compared with IVV embryos, and pathways related to amino acid transport in metabolism were upregulated in IVC and IVMC compared with IVV embryos. Of particular interest, message for cytochrome P450 family 1 subfamily A member 1 (CYP1A1) was only present in the IVC (956 reads) and IVMC (381 reads) embryos but not in the IVV embryos (0 reads). The aryl hydrocarbon receptor (AHR) promotes transcription of CYP1A1, which encodes a monooxygenase involved in xenobiotic metabolism. Moreover, abundance of 12 other AHR targets was increased in IVC and IVMC embryos (false discovery rate &amp;lt;0.05) compared with IVV embryos. Thus, production of porcine embryos invitro may activate AHR, resulting in altered transcriptional profiles and reduced competence. This research was funded by USDA-NIFA (2019-67011-29543).

24 Lipid composition of fresh or frozen sexed bovine blastocysts produced invivo or invitro

Currently, invitro embryo production (IVP) is successfully applied commercially in cattle. However, the high sensitivity of embryos to cryopreservation compared with invivo-derived (IVD) embryos still impairs the dissemination of this biotechnology. Reduced cryotolerance is frequently associated with lipid accumulation in the cytoplasm mainly due to invitro culture conditions. The objective of this study was to evaluate the lipid content of fresh and frozen sexed bovine grade 1 IVP or IVD embryos. The same 8 Holstein heifers were used in a Latin square design for both IVP and IVD embryo production. Zygotes were cultured in synthetic oviductal fluid (SOF) supplemented with 1% oestrus cow serum. The same bull was used for IVP and IVD. All expanded Day 7 blastocysts (n=40 IVP and 40 IVD) were biopsied and sexed. Half of the embryos (n=20 in each group) was slow frozen (1.5M ethylene glycol, 0.1m sucrose) and thawed before lipid extraction. Remaining embryos underwent lipid extraction in the fresh state. Briefly, the liposoluble fraction of the embryos was extracted according to the Bligh and Dyer method using chloroform and methanol. Liquid chromatography–high-resolution mass spectrometry (LC-HRMS) analysis was performed and operated in positive ionization mode. Lipids with variance intensities greater than 30% in quality control samples were removed as well as those identified as background noise. Partial least square discriminant analysis (PLS-DA) was used to show the relationship between variance in the data and difference among embryo origin (IVP vs. IVD), state before extraction (fresh vs. frozen), and sex of the embryos (male vs. female). The differentially lipid species groups were identified using Wilcoxon test, and considered significantly different when P&amp;lt;0.05. LC-HRMS analysis allowed us to identify 75 lipids. PLS-DA showed that embryo origin (IVP vs. IVD) and state before extraction (fresh vs. frozen) can be determined by LC-HRMS profiles by group in PLS-DA plot, despite slight overlaps. Sex of the embryos did not allow us to differentiate the lipid profile. However, 15 lipids varied significantly between male and female IVD, predominantly triglycerides (TG), whereas no lipid varied between the sexes in the IVP homologues. Moreover, 26 lipids varied significantly between IVP and IVD fresh embryos with enrichment of IVP embryos in TG, phosphatidyl choline, cholesteryl ester, and less diglyceride and lysophospholipid (LP) compared with IVD embryos. The comparison of the lipid profiles before and after freezing for IVP embryos showed that only 7 lipids varied significantly between fresh and frozen states with a decrease in LP for the frozen embryos. For the invivo counterparts, 13 lipids varied significantly, including the same LP as those identified for IVP embryos in the same way. Our results showed that the embryonic lipid profile is mainly affected by IVP and slow freezing protocols and, to a lesser extent, by sex. Further studies are needed to improve IVP protocols and optimize the cryotolerance of IVP embryos in cattle.

Oocyte IVM or vitrification significantly impairs DNA methylation patterns in blastocysts as analysed by single-cell whole-genome methylation sequencing.

To explore the mechanisms leading to the poor quality of IVF blastocysts, the single-cell whole-genome methylation sequencing technique was used in this study to analyse the methylation patterns of bovine blastocysts derived from invivo, fresh (IVF) or vitrified (V_IVF) oocytes. Genome methylation levels of blastocysts in the IVF and V_IVF groups were significantly lower than those of the invivo group (P<0.05). In all, 1149 differentially methylated regions (DMRs) were identified between the IVF and invivo groups, 1578 DMRs were identified between the V_IVF and invivo groups and 151 DMRs were identified between the V_IVF and IVF groups. For imprinted genes, methylation levels of insulin-like growth factor 2 receptor (IGF2R) and protein phosphatase 1 regulatory subunit 9A (PPP1R9A) were lower in the IVF and V_IVF groups than in the invivo group, and the methylation level of paternally expressed 3 (PEG3) was lower in the V_IVF group than in the IVF and invivo groups. Genes with DMRs between the IVF and invivo and the V_IVF and IVF groups were primarily enriched in oocyte maturation pathways, whereas DMRs between the V_IVF and invivo groups were enriched in fertilisation and vitrification-vulnerable pathways. The results of this study indicate that differences in the methylation of critical DMRs may contribute to the differences in quality between invitro- and invivo-derived embryos.

11 Invivo-derived embryo pregnancy rates at Maddox Dairy from 2008 to 2018

11 Invivo-derived embryo pregnancy rates at Maddox Dairy from 2008 to 2018

74 Analysis of chromosomal abnormality of bovine IVF embryos based on next-generation sequencing

It has been suggested that bovine IVF embryos have a higher frequency of occurrence of chromosomal abnormalities than invivo-fertilised embryos, which may explain low pregnancy success, but the details have not been clarified (Yao et al. 2018 Sci. Rep. 8, 7460). In this study, chromosomal aneuploidy in blastocysts of bovine IVF and invivo-fertilised was analysed by copy number variations (CNVs) based on next-generation sequencing. The IVF bovine embryos were cultured in well of-the-well culture dishes (LinKID micro25: Dai Nippon Printing) containing 125µL of CR1aa supplemented with 5% calf serum at 38.5°C in 5% O2 and 5% CO2 for 8 days after insemination. Invitro development of embryos was monitored using time-lapse cinematography (Sugimura et al. 2010 Biol. Reprod. 83, 970-78). Invivo embryos were produced by collection of a superstimulated Japanese Black cow. Embryos that reached the blastocyst stage were divided into inner cell mass (ICM) and trophectoderm (TE) fractions by a micromanipulator with a blade. The TE and ICM samples were biopsied individually from 10 IVF and 4 invivo-derived embryos, and extracted DNA was amplified using the SurePlex DNA amplification System (Illumina). The whole-genome amplified DNA libraries were sequenced using MiSeq (Illumina). The sequencing reads were mapped onto the Bos taurus reference genome ARS-UCD1.2, obtained from the National Center for Biotechnology Information. In all 29 autosomal chromosomes and the X chromosome, CNV analysis was performed by CNV-seq (Xie and Tammi 2009 BMC Bioinformatics 10, 80). Male or female Japanese Black cattle DNA sequence was used for the reference genome. The parameter of CNV-seq was run with P-value=0.001, log2=0.6, and window size=1M. Four IVF embryos showed chromosomal duplications or deletions in either ICM- or TE-cell samples (4/10, 40%). The CNV loci between ICM and TE cells were relatively similar in each embryo. One of them was a code 1-expanded blastocyst with normal cleavage. Interestingly, CNV was not identified in another code 1-expanded blastocyst that underwent direct cleavage from 1 cell to 3 or more cells. In invivo embryos, only one embryo had a CNV (1/4, 25%). Observed CNVs in both IVF and invivo embryos were segmental duplication or deletion in each chromosome. Hence, to improve pregnancy success in bovine IVF embryos, cytogenetic evaluation may be useful for quality evaluation of embryos that are prone to chromosomal abnormalities, as well as morphological scoring.

In vitro-produced horse embryos exhibit a very narrow window of acceptable recipient mare uterine synchrony compared with in vivo-derived embryos.

In recent years, the number of equine invitro-produced embryos (IVP) has increased markedly; as yet, there are few reports on what constitutes an 'ideal' recipient for an IVP embryo. This study retrospectively investigated the effects of recipient mare oestrous cycle characteristics on the likelihood of pregnancy after transfer of IVP (n=264) and invivo-derived embryos (n=262). IVP embryos tolerated only a narrow window of recipient mare 'synchrony', with transfer on Day 4 after ovulation resulting in a higher likelihood of ongoing pregnancy (69%) than transfer on Days 3, 5 or 6 (53.2%, 41.3% and 23.1% respectively; P=0.02). In contrast, Day 8 invivo-derived embryos tolerated a wide range of uterine (a)synchrony, with no difference in pregnancy or pregnancy loss for recipients that ovulated between Day 4 and Day 9 before transfer. However, transferring invivo-derived embryos to recipients that had a longer oestrus preceding transfer resulted in higher Day 12 and ongoing pregnancy rate (P<0.01). This effect was not significant in IVP embryos. In conclusion, Day 6-8 IVP blastocysts survive best after transfer to Day 4 recipient mares; Day 8 invivo-derived embryos survive equally well in Day 4-9 recipients, but do better in mares that have a long preceding oestrus.

In vitro production of horse embryos predisposes to micronucleus formation, whereas time to blastocyst formation affects likelihood of pregnancy.

Invitro embryo production is an increasingly popular means of breeding horses. However, success is limited by a high incidence of early embryo loss. Although there are various possible causes of pregnancy failure, chromosomal abnormalities, including aneuploidy, are important potential contributors. This study evaluated the frequency of micronucleus formation as a proxy for aneuploidy in invitro-produced (IVP) and invivo-derived horse blastocysts. Associations between IVP embryo morphology, frequency of nuclear abnormalities and the likelihood of pregnancy were investigated. IVP blastocysts exhibited a higher frequency of cells with micronuclei than invivo-derived embryos (10% vs 1% respectively; P=0.05). This indication of chromosomal instability may explain the higher incidence of pregnancy failure after transfer of IVP embryos. However, the frequency of micronuclei was not correlated with brightfield microscopic morphological characteristics. Nevertheless, IVP embryos reaching the blastocyst stage after Day 9 of invitro culture were less likely to yield a pregnancy than embryos that developed to blastocysts before Day 9 (27% vs 69%), and embryos that had expanded before transfer were more likely to undergo embryonic death than those that had not expanded (44% vs 10%). These findings indicate that current embryo culture conditions are suboptimal and that the speed of embryo development is correlated with pregnancy survival.

141 EXPRESSION STATUS OF AQUAPORINS 3, 7, AND 9 IN BOVINE PRE-IMPLANTATION EMBRYOS

The aquaporins (AQP) are a family of small integral membrane proteins that work as channels for rapid water transport. In mouse embryos, AQP3, AQP7, and AQP9 were found to play important roles in the pre-implantation development or adaptive cellular response to osmotic stress. In addition, because AQP3, AQP7, and AQP9 permeate not only water but also cryoprotectant, such as glycerol, these AQP thought to be involved in the process of cryopreservation. However, little information is available for AQP in bovine embryos. The understanding of the mechanisms mediated by AQP that embryos utilise to survive during culture and the process of cryopreservation will contribute to development of in vitro culture systems and cryopreservation procedures for bovine embryos. The aims of present study were to clarify the expression status of AQP3, AQP7, and AQP9 in bovine pre-implantation embryos, and to evaluate the expression level of AQP3 in in vivo-derived (IVD) and IVF bovine embryos. For production of IVF embryos, cumulus-oocyte complexes (COC) were aspirated from ovaries collected at a local slaughterhouse. The COC were in vitro matured, fertilized, and then cultured for 7 days. The IVD embryos at early blastocyst (EB) and blastocyst (BC) stage were obtained from donor cows treated with superovulation and AI. In experiment 1, in order to clarify the expression of AQP3, AQP7, and AQP9 mRNA in bovine pre-implantation embryos, total RNA was extracted from pools of 30 IVM oocytes, pools of 15 IVF embryos at 2- to 4-cell, 8- to 16-cell, compaction morula (CM), EB, BC, and expanded blastocyst (ExBC) stage, and RT-PCR was performed followed by agarose gel electrophoresis. In experiment 2, in order to clarify the expression status of AQP3, AQP7, and AQP9 during bovine pre-implantation development after zygotic gene activation, total RNA was extracted from pools of 15 IVF embryos at 8- to 16-cell, CM, EB, BC and ExBC stage (n = 5), and relative quantifications of AQP mRNA were performed using real-time RT-PCR. Data were analysed by Scheffé’s method. In experiment 3, AQP3 transcript levels in single IVD and IVF embryos at EB and BC stages (n = 10) was evaluated by real-time RT-PCR. Data were analysed by Mann-Whitney’s U test. In experiment 1, AQP3 and AQP7 transcripts were detected in IVM oocytes and all stages of embryos. AQP9 mRNA was detected in IVM oocytes and in 2- to 4-cell, 8- to 16 cell, CM, and EB stage embryos, but was not detected in BC and ExBC stage embryos. In experiment 2, AQP3 and AQP7 transcript levels were significantly increased from 8- to 16-cell to CM and EB stage, and significantly decreased from EB to BC and ExBC stages (P &lt; 0.05). AQP9 transcript level was significantly decreased from 8- to 16-cell to CM and EB stage (P &lt; 0.05). In experiment 3, AQP3 transcript level in IVF embryos was significantly lower than that in in vivo embryos at the BC stage (P &lt; 0.05). Our results indicate that AQP3 and AQP7 may have specific roles at morula and EB stage in bovine embryos. In addition, AQP3 expression is influenced by developmental condition of bovine embryos.

Transcriptional regulators TRIM28, SETDB1, and TP53 are aberrantly expressed in porcine embryos produced by in vitro fertilization in comparison to in vivo‐ and somatic‐cell nuclear transfer‐derived embryos

In vitro embryo production is important for research in animal reproduction, embryo transfer, transgenics, and cloning. Yet, in vitro-fertilized (IVF) embryos are generally developmentally delayed and are inferior to in vivo-derived (IVV) embryos; this discrepancy is likely a result of aberrant gene expression. Transcription of three genes implicated to be important in normal preimplantation embryo development, TRIM28, SETDB1, and TP53, was determined by quanitative PCR in IVF, somatic-cell nuclear transfer (SCNT), parthenogenetic, and IVV porcine oocytes and embryos. There was no difference in TRIM28 or SETDB1 abundance between oocytes matured in vitro versus in vivo (P > 0.05), whereas TP53 levels were higher in in vitro-matured oocytes. TRIM28 increased from metaphase-II oocytes to the 4-cell and blastocyst stages in IVF embryos, whereas IVV embryos showed a reduction in TRIM28 abundance from maturation throughout development. The relative abundance of TP53 increased by the blastocyst stage in all treatment groups, but was higher in IVF embryos compared to IVV and SCNT embryos. In contrast, SETDB1 transcript levels decreased from the 2-cell to blastocyst stage in all treatments. For each gene analyzed, SCNT embryos of both hard-to-clone and easy-to-clone cell lines were more comparable to IVV than IVF embryos. Knockdown of TRIM28 also had no effect on blastocyst development or expression of SETDB1 or TP53. Thus, TRIM28, SETDB1, and TP53 are dynamically expressed in porcine oocytes and embryos. Furthermore, TRIM28 and TP53 abundances in IVV and SCNT embryos are similar, but different from quantities in IVF embryos. Mol. Reprod. Dev. 81: 552–556, 2014. © 2014 The Authors. Published by Wiley Periodicals, Inc.

Expression and Characterization of Constitutive Heat Shock Protein 70.1 (HSPA‐1A) Gene in In Vitro Produced and In Vivo‐Derived Buffalo (Bubalus bubalis) Embryos

Cells are blessed with a group of stress protector molecules known as heat shock proteins (HSPs), amongst them HSP70, encoded by HSPA-1A gene, is most abundant and highly conserved protein. Variety of stresses hampers the developmental competence of embryos under in vivo and in vitro conditions. Present work was designed to study the quantitative expression of HSPA-1A mRNA in immature oocytes (IMO), matured oocytes (MO), in vitro produced (IVP) and in vivo-derived (IVD) buffalo embryos to assess the level of stress to which embryos are exposed under in vivo and in vitro culture conditions. Further, HSPA-1A gene sequence was analysed to determine its homology with other mammalian sequences. The mRNA expression analysis was carried out on 72 oocytes (40 IMO; 32 MO), 76 IVP and 55 IVD buffalo embryos. Expression of HSPA-1A was found in oocytes and throughout the developmental stages of embryos examined irrespective of the embryo source; however, higher (p < 0.05) expression was observed in 8-16 cell, morula and blastocyst stages of IVP embryos as compared to IVD embryos. Phylogenetic analysis of bubaline HSPA-1A revealed that it shares 91-98% identity with other mammalian sequences. It can be concluded that higher level of HSPA-1A mRNA in IVP embryos in comparison with in vivo-derived embryos is an indicator of cellular stress in IVP system. This study suggests need for further optimization of in vitro culture system in which HSPA-1A gene could be used as a stress biomarker during pre-implantation development.

179 EFFECT OF SERUM DURING CULTURE ON DAY 14 ELONGATED BOVINE EMBRYOS

It has been reported that the addition of serum to embryo culture media alters gene expression and triggers the development of large offspring syndrome. The objectives of this study were to determine gene expression levels in embryos cultured in the absence or presence of 5% calf serum and in vivo-derived (IVD) embryos and to determine the effects of serum on the length of elongated embryos. Abattoir-derived oocytes were obtained from a commercial provider and fertilized at 24 h of maturation with semen from a bull previously used for IVF. At 18 h post-insemination (hpi), embryos were denuded and groups of 15 presumptive zygotes were cultured in 30-μL drops of modified SOF medium with amino acids and 6 mg mL–1 of BSA (mSOFaa). At 72 hpi, cleavage rate was assessed and embryos were randomly allocated into 2 treatments: mSOFaa without and with 5% calf serum. Embryos were then cultured to 168 hpi and blastocyst rates were assessed and recorded. Blastocysts (n = 5 to 10) from each treatment were transferred into synchronized recipients, and Day 14 embryos were recovered 7 days post-transfer. Embryos were photographed, measured, and immediately stored at –80°C in a minimal volume of PBS + 0.1% polyvinyl alcohol. Messenger RNA was isolated using a Dynabeads mRNA Direct Kit™ (Invitrogen, Carlsbad, CA), and reverse transcription was performed using an iScript™ cDNA Synthesis Kit (Bio-Rad Laboratories, Inc., CA). Quantitative PCR was performed to determine the transcript abundance for COX6A, IFNT1a, PLAC8, IGF2R, and GAPDH for each sample. The GAPDH was used as a reference gene, and gene expression was calculated as a ratio of expression levels between each gene of interest and GAPDH. Expression levels for each gene were determined from standard curves generated by serial dilutions of PCR amplicons starting with 0.4 pg/reaction. Blastocyst development rates were higher in embryos cultured with serum compared with the nonserum treatment (14.9 and 7.4% respectively; chi-square, P &lt; 0.001). Lengths of elongated embryos from the serum (3395.3 ± 414.7 μm) and nonserum (2784 ± 741.8 μm) culture treatments differed from the IVD (6297.7 ± 677.2 μm) treatment (mean ± SE; ANOVA, P &lt; 0.0052). There were no differences in the mean expression levels for COX6A, IFNT1a, PLAC8, and IGF2R across treatment groups, but in the serum treatment, 3 out 11 overexpressed IFNT1a, 4 out of 11 overexpressed IGF2R, and 2 out of 11 overexpressed PLAC8, defined as being 2 standard deviations above the mean of the IVD treatment for each respective gene. In the in vitro-produced nonserum and IVD treatments, overexpression by this definition was not observed. Although mean expression levels were not affected by culture with serum under these conditions, very high expression of IFNT1a, IGF2R, and PLAC8 was observed in some embryos cultured with serum, but not in embryos cultured without serum or IVD embryos.

Expression pattern of oxygen and stress-responsive gene transcripts at various developmental stages of in vitro and in vivo preimplantation bovine embryos

The present study examined the expression pattern of oxygen (O 2) and stress-responsive gene transcripts at various preimplantation developmental stages of in vitro produced (IVP) and in vivo derived (IVD) bovine embryos. Embryos were produced in vitro from oocytes matured, fertilized and cultured in synthetic oviductal fluid (SOF) medium under low (5%) and high (20%) O 2 concentrations. In vivo embryos were derived from 18 superovulated and artificially inseminated cows. In IVP and IVD groups, embryos were collected at 2-, 4-, 8-, 16-cell morula and blastocyst stages at specific time points for gene expression analysis. The cleavage rates (69.8 ± 4.8%) did not differ significantly, but blastocyst rates were significantly higher (28.5 ± 3.7%) in low O 2 than those in high O 2 group (18.7 ± 3.9%). Mean cell number in low O 2 (145 ± 12) and high O 2 (121 ± 73) IVP blastocyst were lower ( P < 0.05) than those of IVD blastocyst (223 ± 25). The ICM ratio of IVD blastocyst (26 ± 4) was lower ( P < 0.05) than that of IVP embryos under 5% O 2 (33 ± 5) and 20% O 2 (34 ± 4) concentrations, respectively. Using real time PCR, for the set of target transcripts ( Glut1, Glut5, Sox, G6PD, MnSOD, PRDX5, NADH and Hsp 70.1) analyzed, there were differences in the mRNA expression pattern at 2-, 4-, 8-, 16-cell morula and Day 7 blastocyst stages between the two embryo sources. It can be concluded that, although in vitro bovine embryo culture in SOF medium under low (5%) O 2 concentration provided a more conducive environment in terms of blastocyst formation; differences in the total cell number and gene expression pattern between the IVP and IVD embryos reflected the effect of O 2 concentration.

167 EXPRESSION PATTERN OF GAP JUNCTIONAL CONNEXINS DURING IN VITRO AND IN VIVO PREIMPLANTATION EMBRYO DEVELOPMENT IN BOVINE

During preimplantation development, several connexin proteins are expressed and assembled into gap junctions in the plasma membrane at compaction but the functional significance of connexin diversity remains controversial. The present investigations were (i) to compare the expression pattern of a panel of gap junctional connexin (Cx) gene transcripts from in vitro-produced (IVP) under low (5%) and high (20%) oxygen (O2) concentrations and in vivo-derived (IVD) bovine embryos during various preimplantation stages, and (ii) to evaluate the expression of the same set of gene transcripts in blastocysts derived from IVP (low O2 concentration) and in vivo embryos following a conventional cryopreservation method using 1.5 m ethylene glycol (EG) (Hasler et al. 1997 Theriogenology 48, 563–579). Cumulus-oocyte complexes were matured in TCM199 supplemented with 10% FBS and hormones for 22 h at 39�C, 5% CO2 in air, and then inseminated and cultured in SOF medium for 7 days. IVD embryos were collected from 18 superovulated and artificially inseminated cows. In Experiment I, five pooled embryos from each developmental stage (2-, 4-, 8-, 16-cell, morula, and blastocyst) and embryo source (IVP under low and high O2 concentrations and IVD) and, in Experiment II, Day 7 IVP (low O2 concentration) and IVD blastocysts following cryopreservation and storage for at least 1 week were used for analyzing the expression pattern of gap junctional connexin (Cx30, Cx31, Cx32, Cx36, Cx43, and Cx45) gene transcripts using real-time RT-PCR (four replicates). Normalization of mRNAs at each developmental stage of bovine preimplantation embryos was performed by employing a similar amount of RNA at the reverse transcription (RT) step. This was followed by analyzing by qRT-PCR the target genes using GAPDH as a reference gene. Significant differences in gene expression were analyzed byANOVA and Student's t-test. Relative abundances (RA) of Cx30, Cx31, and Cx32 of IVD embryos were significantly (P &lt; 0.05) higher at all stages compared to that of IVP embryos, except at the blastocyst stage for Cx32. Differences in Cx36 and Cx45 were observed at all stages, with the levels being higher (P &lt; 0.05) in IVD than in IVP embryos. However, the differences at the 4-cell stage between the two embryo sources were not significant. The RA of Cx43 transcript in IVD embryos at 4- and 16-cell stages was higher (P &lt; 0.05) than in IVP embryos, but did not differ at the 2-cell stage. Furthermore, there were differences at the 8-cell and blastocyst stages among IVD, and low and high O2 IVP embryos. Following cryopreservation, RA of all analyzed connexin transcripts of IVD blastocysts were significantly (P &lt; 0.05) higher than that of the low O2 concentration. However, the expression levels in both embryo sources were lower compared to blastocysts before cryopreservation, except for Cx36. To the best of our knowledge, this is the first report on the differences in the expression pattern of a panel of gap junctional connexin gene transcripts during the key developmental stages of IVP embryos with direct comparisons of IVD counterparts.