Review: Endometrial function in pregnancy establishment in cattle

The endometrium is fundamentally required for successful pregnancy in ruminants and species where the posthatching conceptus undergoes a protracted elongation and peri-implantation phase of pregnancy. Moreover, there are substantial waves of pregnancy loss during this pre- and peri-implantation period of pregnancy the precise source of which has not been clearly defined i.e., the maternal uterine contribution to this loss. Understanding the molecular interactions required for successful pregnancy in cattle will allow us to intervene to support pregnancy success during this vulnerable window. The endometrium contributes to most key developmental milestones of pregnancy establishment, including (1) contributing to the regulation of the oestrus cycle, (2) nourishing the preimplantation conceptus, (3) responding to the conceptus to create a more receptive microenvironment, (4) providing essential biophysical support, and (5) signalling and producing factors which affect the mother systemically. This review will summarise what we currently know about conceptus-maternal interactions as well as identify the gaps in our knowledge that could be filled with newer in vitro model approaches. These include the use of microfluidics, organ-on-a-chip devices, and bioinformatic approaches. This will help maximise food production efficiency (both meat and dairy) and decrease the environmental burden, while enhancing our understanding of the fundamental processes required for successful implantation in cattle.

Enhancing neuroimaging genetics through meta-analysis for Tourette syndrome (ENIGMA-TS): A worldwide platform for collaboration

Tourette syndrome (TS) is characterized by multiple motor and vocal tics, and high-comorbidity rates with other neuropsychiatric disorders. Obsessive compulsive disorder (OCD), attention deficit hyperactivity disorder (ADHD), autism spectrum disorders (ASDs), major depressive disorder (MDD), and anxiety disorders (AXDs) are among the most prevalent TS comorbidities. To date, studies on TS brain structure and function have been limited in size with efforts mostly fragmented. This leads to low-statistical power, discordant results due to differences in approaches, and hinders the ability to stratify patients according to clinical parameters and investigate comorbidity patterns. Here, we present the scientific premise, perspectives, and key goals that have motivated the establishment of the Enhancing Neuroimaging Genetics through Meta-Analysis for TS (ENIGMA-TS) working group. The ENIGMA-TS working group is an international collaborative effort bringing together a large network of investigators who aim to understand brain structure and function in TS and dissect the underlying neurobiology that leads to observed comorbidity patterns and clinical heterogeneity. Previously collected TS neuroimaging data will be analyzed jointly and integrated with TS genomic data, as well as equivalently large and already existing studies of highly comorbid OCD, ADHD, ASD, MDD, and AXD. Our work highlights the power of collaborative efforts and transdiagnostic approaches, and points to the existence of different TS subtypes. ENIGMA-TS will offer large-scale, high-powered studies that will lead to important insights toward understanding brain structure and function and genetic effects in TS and related disorders, and the identification of biomarkers that could help inform improved clinical practice.

Bovine scavenger receptor class A (SR-A) exhibit specific patterns of regulation in the endometrium during the oestrous cycle and early pregnancy

In mammals, tight regulation of maternal endometrial function is critical for pregnancy success. In bovine species, endometrial expression of members of the scavenger receptor class A (SR-A) has been listed in high-throughput analyses, but very little is known about the involvement of these immune factors during implantation in mammals. To provide first insights into the contribution of SR-A to endometrial physiology, we analysed the expression and regulation of all members of SR-A (SR-A1, SR-A3-SR-A6) during the oestrous cycle and early pregnancy in cattle. Levels of SR-A1 were increased on Day 20 of pregnancy, whereas SR-A3 levels were increased on Day 13 of the oestrous cycle and of the pregnancy. Although SR-A4 levels were reduced on Day 20 of the oestrous cycle, they remained high in pregnant animals. SR-A5 levels increased by Day 13 of the oestrous cycle and decreased on Day 20, but remained high in pregnant animals. Interferon-τ does not affect SR-A gene expression, whereas progesterone regulates the expression of the SR-A3 and SR-A5 transcripts. Endometrial SR-A3 appeared significantly higher in cows carrying invitro-produced embryos than in AI cows. Our data suggest that members of the SR-A family are involved in endometrial remodelling and regulation of endometrial gland physiology, both processes being critical for implantation in mammals.

The effect of exogenous glucose infusion on early embryonic development in lactating dairy cows

The objective of this study was to examine the effect of intravenous infusion of glucose on early embryonic development in lactating dairy cows. Nonpregnant, lactating dairy cows (n = 12) were enrolled in the study (276 ± 17 d in milk). On d 7 after a synchronized estrus, cows were randomly assigned to receive an intravenous infusion of either 750 g/d of exogenous glucose (GLUC; 78 mL/h of 40% glucose wt/vol) or saline (CTRL; 78 mL/h of 0.9% saline solution). The infusion period lasted 7 d and cows were confined to metabolism stalls for the duration of the study. Coincident with the commencement of the infusion on d 7 after estrus, 15 in vitro-produced grade 1 blastocysts were transferred into the uterine horn ipsilateral to the corpus luteum. All animals were slaughtered on d 14 to recover conceptuses, uterine fluid, and endometrial tissue. Glucose infusion increased circulating glucose concentrations (4.70 ± 0.12 vs. 4.15 ± 0.12 mmol/L) but did not affect milk production or dry matter intake. Circulating β-hydroxybutyrate concentrations were decreased (0.51 ± 0.01 vs. 0.70 ± 0.01 mmol/L for GLUC vs. CTRL, respectively) but plasma fatty acids, progesterone, and insulin concentrations were unaffected by treatment. Treatment did not affect either uterine lumen fluid glucose concentration or the mRNA abundance of specific glucose transporters in the endometrium. Mean conceptus length, width, and area on d 14 were reduced in the GLUC treatment compared with the CTRL treatment. A greater proportion of embryos in the CTRL group had elongated to all length cut-off measurements between 11 and 20 mm (measured in 1-mm increments) compared with the GLUC treatment. In conclusion, infusion of glucose into lactating dairy cows from d 7 to d 14 post-estrus during the critical period of conceptus elongation had an adverse impact on early embryonic development.

Age-Related Changes in Topological Degradation of White Matter Networks and Gene Expression in Chronic Schizophrenia

Current hypotheses stipulate core symptoms of schizophrenia (SZ) result from the brain's incapacity to integrate neural processes. Converging diffusion magnetic resonance imaging and graph theory studies provide evidence of macrostructural alterations in SZ. However, age-related topological changes within and between white matter (WM) networks and its relationship to gene expression with disease progression remain incompletely understood. This cross-sectional study uses network modeling to investigate changes in WM network organization with disease progression in chronic SZ as well its relationship with gene expression in healthy brains. First, we replicate prior findings demonstrating altered global WM network topology in SZ. Novel results show significantly altered age-related network degradation patterns in patients compared with controls. Specifically, controls show stereotyped, linear global network decline with age. In contrast, patients show nonlinear network decline with age. Further analysis reveals lack of significant topological decline in younger adult patients, which is subsequently followed by stereotyped linear decline in older adult patients. Node-specific analyses show significant topological differences in frontal and limbic regions of younger adult patients compared with age-matched controls, which become less pronounced with age in older adult patients compared with age-matched controls. Lastly, we show several gene expression profiles, including DISC1, are associated with age-related changes in WM disconnectivity. Together, these findings provide novel WM topological and genetic evidence supporting neurodevelopmental models of SZ, suggesting that network remodeling continues throughout the third decade of life before stabilizing.

110 Temporal Changes in Endometrial Gene Expression Between Ipsi- and Contralateral Uterine Horns in Cattle

The transfer of an embryo into the uterine horn contralateral to the ovary bearing the corpus luteum has been associated with a decreased pregnancy rate in cattle compared with transfer into the ipsilateral horn. These findings suggest that the environment in the contralateral horn is less conducive to supporting conceptus development than that of the ipsilateral horn. Therefore, this study compared the endometrial transcriptome of the ipsi- and contralateral uterine horns during the luteal phase. Endometrial samples from the ipsi- (IPSI) and contralateral (CONTRA) horns were collected from synchronized nonpregnant beef heifers on Days 5, 7, 13 or 16 post-oestrus (n = 5 heifers per time point). Total RNA was isolated and sequenced. Differences in the transcriptome were determined by edgeR-robust analysis. Principal component analysis found that IPSI and CONTRA have distinct patterns of gene expression on each day, with Day 5 exhibiting the most variation and Day 16 being least variable. Further, the 2 uterine horns had distinct expression patterns on Day 5, with IPSI exhibiting significantly higher variation in gene expression compared twitho CONTRA. EdgeR-robust analysis found 217 (201 up- and 16 down-regulated), 54 (44 up- and 10 down-regulated), 14 (13 up- and 1 down-regulated), and 18 (14 up- and 4 down-regulated) differentially expressed genes (DEG; >2-fold change, false discovery rate P < 0.05) between IPSI and CONTRA endometria on Days 5, 7, 13, and 16 of the oestrous cycle, respectively. The top 5 canonical pathways associated with DEG between IPSI and CONTRA during the luteal phase of the oestrous cycle were involved in signalling pathways regulating pluripotency of stem cells (73/138), progesterone-mediated oocyte maturation (55/89), endometrial cancer (31/51), ErbB signalling pathway (50/87), and mTOR signalling pathway (36/61). The impact of DEG on signalling pathways was assessed using a pathway perturbation algorithm called Signalling Pathway Impact Analysis (SPIA). This topology-based pathway analysis was conducted using the Bioconductor ToPAseq package (https://bioconductor.org/packages/release/bioc/html/ToPASeq.html) and revealed that signalling pathways regulating pluripotency of stem cells showed the highest perturbation score when IPSI was compared with CONTRA irrespective of day. Discovering and cataloguing which pathways are perturbed in each uterine horn throughout the oestrous cycle may contribute to our understanding of the mechanisms underlying early embryonic loss. Ths study was supported by Science Foundation Ireland (13/IA/1983) and the Irish Department of Agriculture, Food and The Marine (13S528).

59 Selected Reaction Monitoring-Based Absolute Quantification of Developmentally Relevant Proteins in Early Bovine Embryos Reveals Differences Between In Vitro and In Vivo Embryo Culture and Between Different Maternal Metabolic Stages

Early embryogenesis is a highly complex developmental process, accompanied by a plethora of changes at the morphological and molecular level. Particularly at the level of proteins, these changes are still poorly characterised and understood. During the first cleavages, the embryo depends mainly on maternal transcripts and proteins that were accumulated and stored during oogenesis until embryonic genome activation (EGA) occurs. In the bovine system, the major EGA takes place at the 8- to 16-cell stage. However, we recently demonstrated by liquid chormatography-tandem mass spectrometry (LC-MS/MS)-based holistic proteome approaches that despite transcriptional and translational silencing, the proteome of the early embryo is highly dynamic (Deutsch et al. 2014; Demant et al. 2015). Based on these findings, we established a targeted LC-MS/MS approach based on multiplexed selected reaction monitoring (mSRM), which facilitates an absolute quantification of 27 proteins relevant in early embryogenesis. Each protein is targeted by 2 independent peptides to facilitate highly reliable quantifications. Nine characteristic developmental stages from germinal vesicle oocyte to hatched blastocyst were analysed (n = 6 per stage), and absolute protein contents are reported as femtomole per embryo, with limits of quantification (LOQ) down to 100 attomoles per embryo. Based on their abundance profiles during maturation, zygote formation, and embryonic development, the 27 proteins could be grouped into 6 SOTA clusters. By principal component analysis (PCA), absolute SRM quantifications of only 9 selected proteins were shown to discriminate between all 9 developmental stages analysed, thus providing molecular fingerprints significant for each developmental stage. We used the 27-plex SRM assay as a powerful readout tool and demonstrated substantial quantitative differences between embryos derived from a well-established in vitro culture system and embryos transferred into the oviduct of living animals for 2 days (in vivo culture). Furthermore, in vivo development of embryos in animals differing in their metabolic stress levels led to significant alterations in the 27-plex SRM profiles. This work was supported by a grant to GJA from Deutsche Forschungsgemeinschaft DFG FOR1041 ‘Germ Cell Potential’ AR 362/7-1 and European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement n° 312097 - FECUND.

67 Influence of Metabolic Status and Genetic Merit for Fertility on Proteomic Composition of Bovine Uterine Luminal Fluid

Intensive selection strategies focusing on increased milk yield over several decades has been associated with a decline in fertility in dairy cows. To study the effect of the genetic merit for fertility and the metabolic status of the female on the oocyte, early embryo and the maternal environment, 2 animal models were established. The genetic merit model involved Holstein heifers with a low (LFH) and high fertility (HFH) index and heifers from the Montbéliarde breed (MBD), known to have good reproductive performance. The metabolic model comprised samples from maiden heifers (MH), postpartum lactating cows (Lact), and non-lactating cows (dried off immediately after calving; Dry). A common pool of Day 7 embryos recovered from superovulated and artificially inseminated Holstein heifers were transferred into synchronised recipients (1/recipient) of the above-mentioned animal models and uterine lumen fluid (ULF) of confirmed pregnant animals was recovered on Day 19 post-oestrus. As communication between the conceptus and the uterine environment is crucial for the successful establishment of pregnancy, we analysed uterine luminal fluid of pregnant cows from both models using a holistic proteomic approach. Using nano-liquid chromatography-tandem mass spectrometry analysis combined with a label-free quantification approach, we analysed the uterine luminal fluid from the uterine horn ipsilateral to the corpus luteum (where the conceptus was located in all cases). A total of 2127 proteins were quantified in all samples of both models. Among this set of proteins, 458 were found to differ significantly (P-value < 0.05) in abundance between the groups of the genetic model, and 141 were altered in abundance in the metabolic model. The majority of proteome differences in ULF samples was found comparing HFH to the LFH group (358) and between Dry and Lact cows (70) in the metabolic model. Evaluation of this dataset using bioinformatic tools comprising DAVID GO and gene set enrichment analysis revealed that the affected proteins were predominantly assigned to the terms “translation”, “monosaccharide metabolic process”, “enzyme inhibitor activity”, “lipid binding”, and “response to oxidative stress”. Our study revealed that metabolic status and genetic merit for fertility lead to quantitative molecular differences at the level of proteins in uterine fluid of pregnant animals, thus altering the microenvironment for the early conceptus. This research was funded by European Union Seventh Framework Programme FP7/2007-2013 under grant agreement no. 312097 (‘FECUND’).

Interferon-tau and fertility in ruminants

Establishment of pregnancy in domestic ruminants includes pregnancy recognition signalling by the conceptus, implantation and placentation. Despite the high fertilisation success rate in ruminants, a significant amount of embryo loss occurs, primarily during early gestation. Interferon-tau (IFNT), a type I interferon that is exclusively secreted by the cells of the trophectoderm of the ruminant conceptus, has been recognised as the primary agent for maternal recognition of pregnancy in ruminants. It produces its antiluteolytic effect on the corpus luteum by inhibiting the expression of oxytocin receptors in the uterine epithelial cells, which prevents pulsatile, luteolytic secretion of prostaglandin F2α by the uterine endometrium. While the importance of IFNT in maternal recognition of pregnancy and prevention of luteolysis in ruminants is unequivocal, important questions, for example, relating to the threshold level of IFNT required for pregnancy maintenance, remain unanswered. This paper reviews data linking IFNT with measures of fertility in ruminants.

Analysis of STAT1 expression and biological activity reveals interferon-tau-dependent STAT1-regulated SOCS genes in the bovine endometrium

Signal transducer and activator of transcription (STAT) proteins are critical for the regulation of numerous biological processes. In cattle, microarray analyses identified STAT1 as a differentially expressed gene in the endometrium during the peri-implantation period. To gain new insights about STAT1 during the oestrous cycle and early pregnancy, we investigated STAT1 transcript and protein expression, as well as its biological activity in bovine tissue and cells of endometrial origin. Pregnancy increased STAT1 expression on Day 16, and protein and phosphorylation levels on Day 20. In cyclic and pregnant females, STAT1 was located in endometrial cells but not in the luminal epithelium at Day 20 of pregnancy. The expression of STAT1 during the oestrous cycle was not affected by progesterone supplementation. In vivo and in vitro, interferon-tau (IFNT) stimulated STAT1 mRNA expression, protein tyrosine phosphorylation and nuclear translocation. Using chromatin immunoprecipitation in IFNT-stimulated endometrial cells, we demonstrated an increase of STAT1 binding on interferon regulatory factor 1 (IRF1), cytokine-inducible SH2-containing protein (CISH), suppressor of cytokine signaling 1 and 3 (SOCS1, SOCS3) gene promoters consistent with the induction of their transcripts. Our data provide novel molecular insights into the biological functions of STAT1 in the various cells composing the endometrium during maternal pregnancy recognition and implantation.

Insights into conceptus elongation and establishment of pregnancy in ruminants

This review integrates established and new information on the factors and pathways regulating conceptus–endometrial interactions, conceptus elongation and establishment of pregnancy in sheep and cattle. Establishment of pregnancy in domestic ruminants begins at the conceptus stage (embryo or fetus and associated extra-embryonic membranes) and includes pregnancy recognition signalling, implantation and the onset of placentation. Survival and growth of the preimplantation blastocyst and elongating conceptus require embryotrophic factors (amino acids, carbohydrates, proteins, lipids and other substances) provided by the uterus. The coordinated and interactive actions of ovarian progesterone and conceptus-derived factors (interferon-τ and prostaglandins) regulate expression of elongation- and implantation-related genes in the endometrial epithelia that alter the uterine luminal milieu and affect trophectoderm proliferation, migration, attachment, differentiation and function. A comparison of sheep and cattle finds both conserved and non-conserved embryotrophic factors in the uterus; however, the overall biological pathways governing conceptus elongation and establishment of pregnancy are likely conserved. Given that most pregnancy losses in ruminants occur during the first month of pregnancy, increased knowledge is necessary to understand why and provide a basis for new strategies to improve pregnancy outcome and reproductive efficiency.

Imprinted and DNA methyltransferase gene expression in the endometrium during the pre- and peri-implantation period in cattle

The endometrium plays a key role in providing an optimal environment for attachment of the preimplantation embryo during the early stages of pregnancy. Investigations over the past 2 decades have demonstrated that vital epigenetic processes occur in the embryo during the preimplantation stages of development. However, few studies have investigated the potential role of imprinted genes and their associated modulators, the DNA methyltransferases (DNMTs), in the bovine endometrium during the pre- and peri-implantation period. Therefore, in the present study we examined the expression profiles of the DNMT genes (3A, 3A2 and 3B) and a panel of the most comprehensively studied imprinted genes in the endometrium of cyclic and pregnant animals. Intercaruncular (Days 5, 7, 13, 16 and 20) and caruncular (Days 16 and 20) regions were analysed for gene expression changes, with protein analysis also performed for DNMT3A, DNMT3A2 and DNMT3B on Days 16 and 20. An overall effect of day was observed for expression of several of the imprinted genes. Tissue-dependent gene expression was detected for all genes at Day 20. Differences in DNMT protein abundance were mostly observed in the intercaruncular regions of pregnant heifers at Day 16 when DNMT3A, DNMT3A2 and DNMT3B were all lower when compared with cyclic controls. At Day 20, DNMT3A2 expression was lower in the pregnant caruncular samples compared with cyclic animals. This study provides evidence that epigenetic mechanisms in the endometrium may be involved with implantation of the embryo during the early stages of pregnancy in cattle.

133 COMPARISON OF ENDOMETRIAL TRANSCRIPTOME CHANGES BETWEEN IPSI- AND CONTRALATERAL HORNS DURING DIESTROUS AND ITS RELATIONSHIP WITH THE ABILITY TO SUPPORT CONCEPTUS ELONGATION IN CATTLE

Data from embryo transfer studies indicate that transfer to the uterine horn contralateral to the ovary containing the corpus luteum (CL) reduces pregnancy rate. The aim of this study was to compare the ipsi- v. contralateral horns in terms of (1) endometrial gene expression and (2) the ability to support conceptus growth to Day 14. In Experiment 1, endometrial samples from the ipsi- and contralateral horns were collected from synchronized nonpregnant heifers slaughtered on Day 5, 7, 13 or 16 post-oestrus (n = 5 per time point) and snap frozen for subsequent analysis. In Experiment 2, fresh Day 7 in vitro-produced blastocysts were transferred to the uterine horn(s) ipsilateral (Group I, n = 9 recipients) or contralateral to the CL (Group C, n = 8) or to both horns (i.e. bilateral, Group B, n = 9) of synchronized recipients (10 embryos transferred per horn per recipient). All recipients were slaughtered on Day 14. Reproductive tracts were recovered and each horn was flushed independently. The number and dimensions (length and width) of recovered conceptuses were recorded independently for each horn. Embryo data were analysed using PROC MIXED in SAS (SAS Institute Inc., Cary, NC, USA). The model had treatment as a fixed effect and heifer within treatment as a random effect. Experiment 1, RNA-Seq analysis of endometrium, detected 217, 54, 14, and 18 differentially expressed genes (>2-fold change, false discovery rate P < 0.05) between ipsi- and contralateral horns on Day 5, 7, 13, and 16 of the oestrous cycle, respectively. In Experiment 2, no differences were observed in the recovery rate of conceptuses on Day 14 from the 3 groups [53.3% (48/90), 48.7% (39/80), and 45% (81/180)], for the I, C, and B transfer groups, respectively. Conceptus length from the ipsi- (2.24 ± 0.35 mm) and contralateral (2.91 ± 0.38 mm) horns was not different (P > 0.05). Thus, significant differences in endometrial gene expression exist between the uterine horns ipsi- and contralateral to the CL in cattle, but those differences do not affect conceptus elongation on Day 14. Research was supported by Science Foundation Ireland (13/IA/1983) and the Irish Department of Agriculture, Food and The Marine (13S528).

Effect of combined exogenous progesterone with luteotrophic support via equine chorionic gonadotrophin (eCG) on corpus luteum development, circulating progesterone concentrations and embryo development in cattle

The aim was to examine the effect of a single intramuscular (i.m.) injection of equine chorionic gonadotrophin (eCG) on Day 3 after oestrus on corpus luteum (CL) development, circulating progesterone and conceptus development in cross-bred beef heifers. In Experiment 1, heifers received: (1) saline, or a single i.m. injection of eCG on Day 3 at (2) 250 IU (3) 500 IU (4) 750 IU or (5) 1000 IU. Administration of eCG resulted in increased luteal tissue area and progesterone and oestradiol concentrations compared with controls. In Experiment 2, heifers received (1) a progesterone-releasing intravaginal device (PRID Delta) from Day 3 to 5 or (2) a PRID Delta from Day 3 to 5 plus a single injection of 750 IU eCG on Day 3. In vitro-produced blastocysts (n = 10 per recipient) were transferred on Day 7 and heifers were slaughtered on Day 14 to assess conceptus development. Administration of eCG reduced the number of short cycles (6.3% vs 31.3%) and increased mean luteal tissue weight (P = 0.02). Insertion of a PRID Delta on Day 3 resulted in an elevation (P < 0.05) in serum progesterone until removal on Day 5. Administration of eCG at the time of PRID Delta insertion resulted in higher progesterone levels (P < 0.05) from Day 10 onwards. Conceptus dimensions were not affected. In conclusion, a single injection of eCG on Day 3 increased CL size and progesterone concentrations and, when given in conjunction with a progesterone-releasing device, appeared to reduce the number of short cycles, presumably due to its luteotrophic nature. The implications of the elevated oestradiol concentrations for embryo quality require further study.

Fertility and genomics: comparison of gene expression in contrasting reproductive tissues of female cattle

To compare gene expression among bovine tissues, large bovine RNA-seq datasets were used, comprising 280 samples from 10 different bovine tissues (uterine endometrium, granulosa cells, theca cells, cervix, embryos, leucocytes, liver, hypothalamus, pituitary, muscle) and generating 260 Gbases of data. Twin approaches were used: an information–theoretic analysis of the existing annotated transcriptome to identify the most tissue-specific genes and a de-novo transcriptome annotation to evaluate general features of the transcription landscape. Expression was detected for 97% of the Ensembl transcriptome with at least one read in one sample and between 28% and 66% at a level of 10 tags per million (TPM) or greater in individual tissues. Over 95% of genes exhibited some level of tissue-specific gene expression. This was mostly due to different levels of expression in different tissues rather than exclusive expression in a single tissue. Less than 1% of annotated genes exhibited a highly restricted tissue-specific expression profile and approximately 2% exhibited classic housekeeping profiles. In conclusion, it is the combined effects of the variable expression of large numbers of genes (73%–93% of the genome) and the specific expression of a small number of genes (<1% of the transcriptome) that contribute to determining the outcome of the function of individual tissues.

73 PROTEOMIC ANALYSIS OF UTERINE LUMINAL FLUID ON DAY 7 OF PREGNANCY IN CATTLE

In vitro fertilization studies have demonstrated that contact with the female reproductive tract is not necessary in order for the embryo to reach the hatched blastocyst stage. Furthermore, the endometrial transcriptome does not differ between cyclic and pregnant cattle before maternal recognition around Days 15 to 16, suggesting that before that time the cow does not know she is pregnant. Nonetheless, embryo quality is significantly improved by exposure to reproductive tract secretions. Therefore, the aims of this study were to (1) characterise the protein content of uterine luminal fluid (ULF) on Day 7 of pregnancy and the oestrous cycle; (2) identify if differences in ULF composition exist between pregnant and cyclic heifers on Day 7; and (3) determine if blastocyst-derived proteins contribute to ULF composition. Following oestrus synchronization, heifers observed in standing oestrus were randomly assigned to either inseminated (AI: n = 12) or cyclic control (C: n = 6) groups. At slaughter, the uterine horn ipsilateral to the corpus luteum was flushed with 10 mL of PBS. In the AI group, the presence of an appropriately developed embryo was noted (n = 8), and the ULF of both confirmed pregnant and cyclic heifers was clarified by centrifugation at 1000 × g for 15 min at 4°C. Blastocyst-conditioned medium was produced by culturing in vitro-produced blastocysts (n = 300) for 24 h in synthetic oviduct fluid (SOF; groups of 50 blastocysts in 500 µL of SOF). After 24 h the conditioned medium (n = 6 pools), along with contemporaneous blanks (n = 6), was collected and snap frozen. Proteomic analysis of ULF as well as blastocyst-conditioned medium was carried out by nano-LC tandem mass spectrometry (nano-LC-MS/MS). A total of 661 proteins were identified in the ULF of heifers on Day 7 with >95% confidence in at least 4 out of the 6 animals analysed per group. The most abundant proteins were myosin-9, cytoplasmic dynein 1 heavy chain 1-like, fatty acid synthase isoform X1, serum albumin, and aminopeptidase N. No differences were detected between pregnant and cyclic ULF. Of the proteins identified, the biological processes of gene expression (23.8%), small molecule metabolic process (22.6%), and cellular protein metabolic process (17.8%) were most overrepresented. Interestingly, 400 proteins were associated with extracellular exosome as well as extracellular space (87 proteins) and extracellular region (58). Analysis of blastocyst-conditioned medium identified 11 proteins that were not detected in the contemporaneous blanks, of which one (α-1-acid glycoprotein) was also detected in Day 7 ULF. In conclusion, no differences in the ULF composition between pregnant and cyclic heifers were observed on Day 7, consistent with studies on the endometrial transcriptome. A large proportion of the proteins detected are associated with the extracellular space region and may represent candidate proteins that can be added to embryo culture media to enhance early development. Research was funded by Science Foundation Ireland (13/IA/1983).

71 CIRCULATING microRNAs AS POTENTIAL BIOMARKERS OF EARLY PREGNANCY IN HIGH-PRODUCING DAIRY COWS

Lactation induces changes in the metabolic status of postpartum dairy cows that negatively affects the likelihood of pregnancy establishment. At present, pregnancy diagnosis with confidence is only possible after the third week of gestation. Earlier diagnosis could facilitate earlier re-breeding, reduce calving intervals, and improve profits for the industry. MicroRNAs (miRNAs) released in body fluids have been identified as minimally invasive biomarkers of several diseases. In addition, distinct miRNA profiles have been directly related to specific stages of human pregnancy. The aim of this study was to profile circulating miRNAs in the blood of high-producing dairy cows in order to identify biomarkers of early pregnancy. In-calf primiparous Holstein-Friesian cows (n = 22) with a similar economic breeding index were used. At calving, cows were randomly assigned to one of two groups: (1) lactating (n = 11; milked twice per day) or (2) non-lactating (n = 11; dried off immediately). Around 65 to 75 days postpartum (dpp), oestrous cycles were synchronized and a single embryo from a superovulated Holstein-Friesian donor was transferred at Day 7 post-oestrus. Plasma samples were analysed at Day 13 (initiation of conceptus elongation) and at Day 19 (initiation of implantation). Pregnancy rate, established by the presence of conceptus at Day 19, was 5/11 (45%) for lactating and 8/11 (73%) for non-lactating cows, respectively. Circulating miRNA levels were profiled in 4 animals per group in non-lactating pregnant, and lactating pregnant and nonpregnant cows at selected timepoints using Illumina HiSEqn 2000 (Illumina Inc., San Diego, CA, USA) for smallRNA sequencing. Annotation and discovery of miRNAs were done using MirDeep2, and read counts were analysed using edgeR to identify differentially expressed miRNAs. Target genes analysis was run with miRWalk and pathways interactions were built using Cytoscape (P ≤ 0.05). Differentially abundant miRNAs between lactating and non-lactating cows were found at both time points (FDR ≤ 0.05). At Day 13, non-lactating cows had a distinct miRNA profile compared with lactating cows showing 8 differentially expressed miRNA (6 v. pregnant and 2 v. nonpregnant cows). At Day 19, no significant differences were found within pregnant cows, but 5 differentially expressed miRNAs were identified between pregnant and nonpregnant cows, regardless of metabolic status. Interestingly, one miRNA, bta-mir140, was up-regulated in non-lactating pregnant cows from Day 13 onwards compared with nonpregnant cows. Furthermore, the same miRNA was up-regulated in lactating pregnant v. nonpregnant at Day 19. Among bta-mir140 target genes, CD274, SLC44A4, CXCL12, and SIRPA were strictly associated with immune tolerance. In conclusion, the maternal plasma miRNome may represent an early indicator of pregnancy status. In particular, the up-regulation of bta-mir140 in pregnant cows suggests that this miRNA may be a good candidate as an early biomarker of fertility. Furthermore, the positive correlation between this miRNA and pathways involved in T-cell response may indicate a role of immune tolerance in preventing rejection at the initiation of implantation.

Evidence of a molecular clock in the ovine ovary and the influence of photoperiod

The influence of the central circadian clock on reproductive timing is well established. Much less is known about the role of peripheral oscillators such as those in the ovary. We investigated the influence of photoperiod and timing of the LH surge on expression of circadian clock genes and genes involved in steroidogenesis in ovine ovarian stroma. Seventy-two Suffolk cross ewes were divided into two groups, and their estrous cycles were synchronized. Progestagen sponge removal was staggered by 12 hours between the groups such that expected LH peak would occur midway through either the light or dark phase of the photoperiodic cycle. Four animals from each group were killed, and their ovaries were harvested beginning 36 hours after sponge removal, at 6-hour intervals for 48 hours. Blood was sampled every 3 hours for the period 24 to 48 hours after sponge removal to detect the LH surge. The interval to peak LH did not differ between the groups (36.2 ± 1.2 and 35.6 ± 1.1 hours, respectively). There was an interaction between group and the time of sponge removal on the expression of the core clock genes ARNTL, PER1, CRY1, CLOCK, and DBP (P < 0.01, P < 0.05, P < 0.01, P < 0.01, and P < 0.01, respectively). As no significant interaction between group and time of day was detected, the datasets were combined. Statistically significant rhythmic oscillation was observed for ARNTL, CLOCK, CRY1 (P < 0.01, respectively), PTGS2, DBP, PTGER2, and CYP17A1 (P < 0.05, respectively), confirming the existence of a time-sensitive functionality within the ovary, which may influence steroidogenesis and is independent of the ovulatory cycle.

100 EMBRYO SURVIVAL AND CONCEPTUS ELONGATION FOLLOWING ASYNCHRONOUS EMBRYO TRANSFER IN CATTLE

Maternal progesterone (P4) regulates early conceptus growth and development in ruminants. Early embryo transfer studies in sheep and cattle demonstrated a need for close synchrony between the embryo and the uterine environment of the recipient. However, manipulating P4 may be one way of strategically regulating the temporal changes that normally occur in the uterine environment in order to allow flexibility in the timing of embryo transfer. For example, previous studies have demonstrated that P4 administration during the first few days of the oestrous cycle facilitates pregnancy establishment with older embryos. The aim of this study was to examine the effect of embryo-uterine synchrony on conceptus elongation in cattle. Oestrous cycles of crossbred beef heifers were synchronised using an 8-day P4-Releasing Intravaginal Device (PRID Delta®, CEVA, Mountain View, CA, USA) with administration of a prostaglandin F2α analogue (Enzaprost®, CEVA; 5 mL equivalent to 25 mg of dinoprost) given on the day before PRID removal. Heifers were checked for signs of oestrus 4 times per day commencing 30 h after PRID withdrawal. Only those seen in standing oestrus (n = 50) were randomly assigned to 1 of 5 treatment groups to receive Day 7 in vitro-produced blastocysts (n = 10 per recipient) (1) on Day 5 post-oestrus; (2) on Day 5, with P4 supplementation via PRID from Day 3 to 5 + 750 IU of eCG at PRID insertion; (3) on Day 5, PRID Delta from Day 3 to 5 plus 3000 IU of hCG at PRID insertion; (4) on Day 7, or (5) on Day 9. At embryo age Day 14, all heifers were slaughtered and the uterus was flushed to recover and measure conceptuses. Data are summarised in Table 1. Fewer recipients yielded conceptuses (P < 0.05) and fewer conceptuses overall were recovered (P < 0.05) following transfer on Day 5 compared with Day 7 or Day 9. Supplementation with P4 resulted in short cycles (evidenced by corpus luteum regression and/or a recent ovulation at slaughter) in 33.3 to 54.5% of recipients receiving embryos on Day 5. Mean conceptus length was greater (P < 0.05) following transfer to an advanced uterus. In conclusion, transfer of embryos to a retarded (Day 5) uterine environment results in poor embryo survival. Supplementation with P4 shortened the interoestrous period in a significant number of heifers. Transfer to an advanced uterine environment promotes conceptus elongation, presumably driven by P4. Table 1.Embryo survival and conceptus length data

SOCS genes expression during physiological and perturbed implantation in bovine endometrium

In mammals, suppressor of cytokine signalling (CISH, SOCS1 to SOCS7) factors control signalling pathways involved in the regulation of numerous physiological processes including pregnancy. In order to gain new insights into the biological functions of SOCS in the endometrium, a comprehensive analysis of SOCS gene expression was carried out in bovine caruncular (CAR) and intercaruncular (ICAR) tissues collected i) during the oestrous cycle, ii) at the time of maternal recognition of pregnancy and at implantation in inseminated females, iii) following uterine interferon-tau (IFNT) infusion at day 14 post-oestrus, iv) following a period of controlled intravaginal progesterone release and v) following transfer of embryos by somatic-cell nuclear transfer (SCNT). The regulatory effects of IFNT on in vitro cultured epithelial and stromal cells were also examined. Altogether, our data showed that CISH, SOCS4, SOCS5 and SOCS7 mRNA levels were poorly affected during luteolysis and pregnancy. In contrast, SOCS1, SOCS2, SOCS3 and SOCS6 mRNA levels were strongly up-regulated at implantation (day 20 of pregnancy). Experimental in vitro and in vivo models demonstrated that only CISH, SOCS1, SOCS2 and SOCS3 were IFNT-induced genes. Immunohistochemistry showed an intense SOCS3 and SOCS6 staining in the nucleus of luminal and glandular epithelium and of stromal cells of pregnant endometrium. Finally, SOCS3 expression was significantly increased in SCNT pregnancies in keeping with the altered immune function previously reported in this model of compromised implantation. Collectively, our data suggest that spatio-temporal changes in endometrial SOCS gene expression reflect the acquisition of receptivity, maternal recognition of pregnancy and implantation.

White matter microstructural abnormalities in families multiply affected with bipolar I disorder: a diffusion tensor tractography study

BACKGROUND

White matter (WM) abnormalities are proposed as potential endophenotypic markers of bipolar disorder (BD). In a diffusion tensor imaging (DTI) voxel-based analysis (VBA) study of families multiply affected with BD, we previously reported that widespread abnormalities of fractional anisotropy (FA) are associated with both BD and genetic liability for illness. In the present study, we further investigated the endophenotypic potential of WM abnormalities by applying DTI tractography to specifically investigate tracts implicated in the pathophysiology of BD.

METHOD

Diffusion magnetic resonance imaging (MRI) data were acquired from 19 patients with BD type I from multiply affected families, 21 of their unaffected first-degree relatives and 18 healthy volunteers. DTI tractography was used to identify the cingulum, uncinate fasciculus (UF), arcuate portion of the superior longitudinal fasciculus (SLF), inferior longitudinal fasciculus (ILF), corpus callosum, and the anterior limb of the internal capsule (ALIC). Regression analyses were conducted to investigate the effect of participant group and genetic liability on FA and radial diffusivity (RD) in each tract.

RESULTS

We detected a significant effect of group on both FA and RD in the cingulum, SLF, callosal splenium and ILF driven by reduced FA and increased RD in patients compared to controls and relatives. Increasing genetic liability was associated with decreased FA and increased RD in the UF, and decreased FA in the SLF, among patients.

CONCLUSIONS

WM microstructural abnormalities in limbic, temporal and callosal pathways represent microstructural abnormalities associated with BD whereas alterations in the SLF and UF may represent potential markers of endophenotypic risk.

Temporal regulation of fibroblast growth factors and their receptors in the endometrium and conceptus during the pre-implantation period of pregnancy in cattle

We hypothesised that the expression pattern of members of the fibroblast growth factor (FGF) family would be altered in the endometrium as the oestrous cycle/early pregnancy progressed associated with changes in the expression pattern of their receptors in the developing embryo/conceptus. Expression of FGF1 and FGF10 transcript variants 1 and 2 increased significantly as the oestrous cycle/early pregnancy progressed. Neither progesterone (P4) supplementation nor pregnancy status significantly affected the expression of any of the FGF ligands studied. However, there was a significant interaction between day, pregnancy and P4 status on FGF2 expression (P<0.05) and a significant interaction between P4 status and day on FGF10_tv2 expression. FGF10 protein was localised in the luminal and glandular epithelium as well as the stroma but was not detected in the myometrium. By RNA sequencing, the expression of FGF ligands in the developing embryo/conceptus was found to be minimal. The expression of FGF receptor 1 (FGFR1), FGFR2, FGFR3, FGFR4, FGFRL1 and FRS3 was significantly affected by the stage of conceptus development. Interestingly, the expression of FGFR1 and FGFR4 was higher during early embryo development (days 7–13, P<0.05) but decreased on day 16 (P<0.05) while FGFR2 (P<0.001) expression was similar from day 7 through to day 13, with a significant increase by day 16 (P<0.05) that was maintained until day 19 (P>0.05). In conclusion, these data demonstrate that FGF ligands are primarily expressed by the endometrium and their modulation throughout the luteal phase of the oestrous cycle/early pregnancy are associated with alterations in the expression of their receptors in the embryo/conceptus.

Paradoxical effect of supplementary progesterone between Day 3 and Day 7 on corpus luteum function and conceptus development in cattle

The aim of the present study was to investigate the effect of short-term progesterone (P4) supplementation during the early metoestrous period on circulating P4 concentrations and conceptus development in cattle. The oestrous cycles of cross-bred beef heifers were synchronised using a 7-day P4-releasing intravaginal device (PRID® Delta; 1.55 g P4) treatment with administration of a prostaglandin F2α analogue (Enzaprost; CEVA Sante Animale) the day before PRID® Delta removal. Only those heifers recorded in standing oestrus (Day 0) were used. In Experiment 1, heifers were randomly assigned to one of five groups: (1) control: no treatment; (2) placebo: insertion of a blank device (no P4) from Day 3 to Day 7; (3) insertion of a PRID® Delta from Day 3 to Day 7; (4) insertion of a PRID® Delta from Day 3 to Day 5; or (5) insertion of a PRID® Delta from Day 5 to Day 7. In vitro-produced blastocysts were transferred to each heifer in Groups 2–5 on Day 7 (n = 10 blastocysts per heifer) and conceptuses were recovered when heifers were killed on Day 14. Based on the outcome of Experiment 1, in Experiment 2 heifers were artificially inseminated at oestrus and randomly assigned to one of three treatment groups: (1) placebo; (2) PRID from Day 3 to Day 5; or (3) PRID from Day 3 to Day 7. All heifers were killed on Day 16 and recovered conceptuses were incubated in synthetic oviducal fluid medium for 24 h; spent media and uterine flushes were analysed for interferon-τ (IFNT). In both experiments, daily blood samples were taken to determined serum P4 concentrations. Data were analysed using the PROC MIXED procedure of SAS (SAS Institute, Cary, NC, USA). Insertion of a PRID resulted in an increase (P < 0.05) in serum P4 that declined following removal. In Experiment 1, P4 supplementation from Day 3 to Day 5 (17.0 ± 1.4 mm) or Day 3 to Day 7 (11.3 ± 2.3 mm) increased conceptus length compared with placebo (2.1 ± 1.8 mm). Serum P4 was significantly lower from Day 9 to Day 14 (P < 0.05) and the weight of the Day 14 corpus luteum (CL) was lower in the PRID Day 3–7 group than the placebo or control groups. In Experiment 2, supplementation from Day 3 to Day 5 (94.0 ± 18.8 mm) or Day 3 to Day 7 (143.6 ± 20.6 mm) increased conceptus length on Day 16 compared with placebo (50.3 ± 17.4 mm). Serum P4 was significantly lower in the two supplemented groups following PRID removal compared with placebo (P < 0.05) and was associated with a lower CL weight in the Day 3–7 group. Conceptus length was strongly correlated with the IFNT concentration in the uterine flush (r = 0.58; P = 0.011) and spent culture medium (r = 0.68; P < 0.002). The findings of the present study highlight the somewhat paradoxical effects of P4 supplementation when given in the early metoestrous period in terms of its positive effect on conceptus development and its potentially negative effects on CL lifespan.

77 OVIDUCT - EMBRYO INTERACTIONS: TWO-WAY TRAFFIC OR A ONE-WAY STREET? TRANSCRIPTOMIC RESPONSE OF THE BOVINE OVIDUCT TO THE PRESENCE OF AN EMBRYO

Despite clear evidence of a two-way interaction between the developing conceptus and the uterine endometrium in early pregnancy, the evidence for reciprocal cross-talk during the transit of the embryo through the oviduct is less clear. The aims were (1) to characterise the transcriptome of the bovine oviduct at the initiation of embryonic genome activation (EGA), (2) to examine the effect, if any, of the presence of an embryo on the oviduct transcriptome, and (3) to compare gene expression in the ampulla and isthmus of the oviduct ipsilateral to the corpus luteum. The oestrous cycles of cross-bred beef heifers were synchronized and those recorded in standing oestrus were randomly allocated to control group, nonbred (n = 7), or AI group (n = 11). All heifers were slaughtered on Day 3 after oestrus. The oviducts from each animal were isolated, straightened, and cut in half (ampulla and isthmus). Each portion was flushed with 500 μL of PBS to confirm the presence of an oocyte/embryo and was then opened and scraped longitudinally to obtain epithelial cells. Cells were snap-frozen in liquid nitrogen for microarray analysis. All recovered oocytes and embryos were located in the isthmus of the oviduct ipsilateral to the corpus luteum. The recovery rate was 72.7% (8/11) and 83.3% (5/6) for pregnant and cyclic animals, respectively. The stage of the recovered embryos was as follows: 4-cell stage (n = 1), 8-cell stage (n = 5), and 8–16 cell stage (n = 2), whereas in the cyclic group all recovered structures were unfertilized oocytes. The cells of the isthmus from ipsilateral and contralateral oviducts from 5 cyclic and 5 pregnant animals (8-cell embryos) and the ipsilateral ampulla cells from the pregnant animals were used for microarray analysis (Affymetrix Bovine ST array, Affymetrix, Santa Clara, CA, USA). Array data were analysed using BioConductor packages in R and custom CDF files downloaded from MBNI. Preprocessing of raw data was performed with RMA, and differential expression was assessed by linear modelling implemented in the limma package. Genes displaying P < 0.05 after adjustment for multiple testing were considered differentially expressed. A total of 18 809 probe sets were assessed for differential expression. Comparison of pregnant and cyclic oviduct epithelium revealed no significantly altered genes. However, comparison of the isthmus and ampulla of the ipsilateral oviduct in pregnant animals revealed 4011 (P < 0.05) and 2327 (P < 0.01) differentially expressed genes. Some of the gene ontologies involved in biological processes included fatty acid metabolism, cell adhesion, cell morphogenesis, cellular developmental process, and reproduction. In conclusion, we have characterised the transcriptome of the bovine oviduct epithelium at the initiation of embryonic genome activation on Day 3 post-oestrus in pregnant and cyclic heifers. Although large differences in gene expression were observed between the isthmus and ampulla, data suggest that the presence of an 8-cell embryo had no effect on the transcriptome of the cells of the isthmus, although a local effect at the precise position of the embryo cannot be ruled out.

76 RELATIONSHIP BETWEEN BLASTOCYST CELL NUMBER AT EMBRYO TRANSFER AND CONCEPTUS ELONGATION ON DAY 14: CAN SUPPLEMENTARY PROGESTERONE RESCUE SMALL EMBRYOS?

Conceptus size on Day 14 following multiple embryo transfer of Day 7 in vitro-produced blastocysts varies greatly within animal. One explanation for this variation may be related to blastocyst cell number at the time of transfer. The aim of this study was to examine the effect of Day 7 blastocyst cell number on Day 14 conceptus size and to examine the effect of progesterone (P4) supplementation on embryo development following the transfer of Day 7 blastocysts containing a low total cell number. The oestrous cycles of crossbred beef heifers were synchronised using an 8-day CIDR (1.38 g of P4) treatment with administration of a prostaglandin F2α analogue (Estrumate™, Merck Animal Health, Summit, NJ, USA) on the day before CIDR removal. Only those heifers recorded in standing oestrus (Day 0) were used. Heifers were randomly assigned to 1 of 4 treatment groups: (1) Control: large blastocysts (high total cell number), (2) Control: small blastocysts (low total cell number), (3) small blastocysts plus a single intramuscular injection of 3000 IU of hCG (Chorulon®, Merck Animal Health) on Day 2 after oestrus, or (4) small blastocysts plus insertion of a vaginal progesterone insert (PRID, 1.55 g of P4) between Days 3 to 5 after oestrus. In vitro-produced blastocysts were transferred to each heifer on Day 7 (n = 10 blastocysts per heifer) and conceptuses were recovered at slaughter on Day 14. A sample of blastocysts was fixed and stained using Hoechst 33342 to determine the mean total cell number per group. Daily blood samples were collected from Day 0 to 14 to measure serum P4 concentrations. Data were analysed using the PROC MIXED procedure of SAS (SAS Institute Inc. Cary, NC, USA). Total cell number on Day 7 was significantly lower in small compared with large blastocysts (72.4 ± 3.93 v. 144.8 ± 3.90; P < 0.05). Conceptus recovery rate was 53.8% overall (140/260) and was highest in the large blastocyst group (68.3%, 41/60) compared with the other groups (45.7–55.0%). Concentrations of serum P4 were similar in the 2 unmanipulated recipient groups but were significantly elevated (P < 0.05) by Day 8 in hCG-treated heifers and on Days 4 and 5 in the PRID group (P < 0.003). In the absence of supplemental P4, Day 14 conceptuses resulting from the transfer of small blastocysts (2.48 ± 0.54 mm) were smaller than those from large blastocysts (3.32 ± 0.52 mm). Administration of hCG on Day 2 approximately doubled conceptus length on Day 14 (4.94 ± 1.15 mm), whereas insertion of a PRID from Day 3 to 5 increased conceptus length ~5-fold (13.09 ± 2.11 mm; P < 0.05) compared with controls. In conclusion, results indicate that supplemental P4 is capable of “rescuing” poor quality blastocysts, presumably via the now well-described actions on the endometrium and consequent effects on uterine lumen fluid composition. Supported by Science Foundation Ireland (07/SRC/B1156).

109 EFFECT OF SHORT TERM PROGESTERONE SUPPLEMENTATION ON CIRCULATING PROGESTERONE CONCENTRATION, CORPUS LUTEUM SIZE, AND EARLY EMBRYO DEVELOPMENT IN CATTLE

The aim of this study was to investigate the effect of short term progesterone (P4) supplementation on circulating P4 concentrations, corpus luteum (CL) size, and conceptus development in cattle. The oestrous cycles of crossbred beef heifers were synchronised using a 7-day PRID® Delta (1.55 g P4) treatment with administration of a PGF2α analog (Enzaprost®) the day before PRID® Delta removal. Only those recorded in standing oestrus (Day 0) were used. In Experiment 1, heifers were randomly assigned to 1 of 5 groups: (1) control: no treatment, (2) placebo: insertion of a blank device (no P4) from Day 3 to 7, (3) insertion of a PRID® Delta from Day 3 to 7, (4) insertion of a PRID® Delta from Day 3 to 5, or (v5) insertion of a PRID® Delta from Day 5 to 7. In vitro produced blastocysts were transferred to each heifer on Day 7 (10 blastocysts per heifer) and conceptuses were recovered at slaughter on Day 14. In Experiment 2 heifers were artificially inseminated at oestrus and randomly assigned to 1 of 3 treatment groups (1) placebo, (2) PRID® Delta from Day 3 to 5, or (3) PRID® Delta from Day 3 to 7. All heifers were slaughtered on Day 16, and recovered conceptuses were incubated in synthetic oviduct fluid medium for 24 h; spent media and uterine flushes were analysed for interferon-tau (IFNT). In both experiments, daily blood samples were taken to measure serum P4 concentration. Data were analysed using the PROC MIXED procedure of SAS (SAS Institute Inc., Cary, NC, USA). Insertion of a PRID® Delta resulted in an increase (P < 0.05) in serum P4, which declined following removal. In Experiment 1, serum P4 concentration was significantly lower from Day 9 to 14 (P < 0.05) and Day 14 CL weight was lower in the PRID® Delta Day 3 to 7 group than the placebo or control groups. P4 supplementation from Day 3 to 5 (17.0 ± 1.4 mm) or Day 3 to 7 (11.3 ± 2.3 mm) increased conceptus length compared to the placebo (2.1 ± 1.8 mm). In Experiment 2, serum P4 was significantly lower in the two supplemented groups following PRID® Delta removal compared with the placebo (P < 0.05) and was associated with a lower CL weight in the Day 3 to 7 group. Supplementation from Day 3 to 5 (94.0 ± 18.8 mm) or Day 3 to 7 (143.6 ± 20.6 mm) increased conceptus length on Day 16 compared to the placebo (50.3 ± 17.4 mm). Conceptus length was strongly correlated with the concentration of IFNT in the uterine flush (r = 0.58; P = 0.011) and spent culture medium (r = 0.68; P < 0.002). These findings highlight the somewhat paradoxical effects of P4 supplementation when given in the early metoestrus period in terms of its positive effect on conceptus development and its potentially negative effects on CL lifespan. Supported by CEVA Sante Animale and Science Foundation Ireland (07/SRC/B1156).

Altered endometrial immune gene expression in beef heifers with retarded embryos

The aim of the present study was to compare endometrial gene expression profiles in a group of beef heifers yielding viable or retarded embryos on Day 7 after oestrus as a means of potentially explaining differences in embryo survival rates. Heifers were classified as either: (1) viable, when the embryo collected on Day 7 after oestrus was at the correct developmental stage (i.e. morula/early blastocyst); or (2) retarded, when the embryo was arrested at the 2–16-cell stage. The focus of the present study was on genes that were associated with either the pro- or anti-inflammatory immune response. Endometrial gene expression was determined using quantitative real-time polymerase chain reaction analysis. Expression of the β-defensin (DEFB1), interferon (IFN)-α (IFNA), IFN-γ (IFNG), interleukin (IL)-6 (IL6), IL-10 (IL10), forkhead box P3 (FOXP3) and natural cytotoxicity triggering receptor 1 (NCR1) genes was lower in endometria from viable than retarded heifers. Expression of the nuclear factor of kappa light polypeptide gene enhancer in B cells 1 (NKFB1), transforming growth factor (TGF)-β (TGFB), IFN-γ-inducible protein 16 (IFI16) and IL-21 (IL21) genes was higher in viable than retarded heifers. We propose that small disturbances in the expression of immune genes in the endometrium on Day 7 after oestrus can have detrimental effects on embryo survival.

Endometrial response of beef heifers on day 7 following insemination to supraphysiological concentrations of progesterone associated with superovulation

Ovarian stimulation is a routine procedure in assisted reproduction to stimulate the growth of multiple follicles in naturally single-ovulating species including cattle and humans. The aim of this study was to analyze the changes induced in the endometrial transcriptome associated with superovulation in cattle and place these observations in the context of our previous data on changes in the endometrial transcriptome associated with elevated progesterone (P4) concentrations within the physiological range and those changes induced in the embryo due to superovulation. Mean serum P4 concentrations were significantly higher from day 4 to day 7 in superovulated compared with unstimulated control heifers (P < 0.05). Between-group analysis revealed a clear separation in the overall transcriptional profile of endometria from unstimulated control heifers (n = 5) compared with superovulated heifers (n = 5). This was reflected in the number of differentially expressed genes (DEGs) identified between the two groups with 795 up- and 440 downregulated in superovulated endometria. Ten times more genes were altered by superovulation (n = 1,234) compared with the number altered due to elevated P4 within physiological ranges by insertion of a P4-releasing intravaginal device (n = 124) with only 22 DEGs common to both models of P4 manipulation. Fewer genes were affected by superovulation in the embryo compared with the endometrium, (443 vs. 1,234 DEGs, respectively), and the manner in which genes were altered was different with 64.5% of genes up- and 35.5% of genes downregulated in the endometrium, compared with the 98.9% of DEGs upregulated in the embryo. In conclusion, superovulation induces significant changes in the transcriptome of the endometrium which are distinct from those in the embryo.

Evidence for an early endometrial response to pregnancy in cattle: both dependent upon and independent of interferon tau

The aims of this study were to 1) identify the earliest transcriptional response of the bovine endometrium to the presence of the conceptus (using RNAseq), 2) investigate if these genes are regulated by interferon tau (IFNT) in vivo, and 3) determine if they are predictive of the pregnancy status of postpartum dairy cows. RNAseq identified 459 differentially expressed genes (DEGs) between pregnant and cyclic endometria on day 16. Quantitative real-time PCR analysis of selected genes revealed PARP12, ZNFX1, HERC6, IFI16, RNF213, and DDX58 expression increased in pregnant compared with cyclic endometria on day 16 and were directly upregulated by intrauterine infusion of IFNT in vivo for 2 h ( P < 0.05). On day 13 following estrous endometrial expression of nine genes increased [ ARHGAP1, MGC127874, LIMS2, TBC1D1, FBXL7, C25H16orf71, LOC507810, ZSWIM4, and one novel gene (ENSBTAT00000050193)] and seven genes decreased ( SERBP1, SRGAP2, AL7A1, TBK1, F2RL2, MGC128929, and WBSCR17; P < 0.05) in pregnant compared with cyclic heifers. Of these DEGs, significant differences in expression between pregnant and cyclic endometria were maintained on day 16 for F2RL2, LIMS2, LOC507810, MGC127874, TBC1D1, WBSCR17, and ZSWIM4 ( P < 0.05) both their expression was not directly regulated by IFNT in vivo. Analysis of the expression of selected interferon-stimulated genes in blood samples from postpartum dairy cows revealed a significant increase ( P < 0.05) in expression of ZXFX1, PARP12, SAMD9, and HERC6 on day 18 following artificial insemination in cows subsequently confirmed pregnant compared with cyclic controls. In conclusion, RNAseq identified a number of novel pregnancy-associated genes in the endometrium of cattle during early pregnancy that are not regulated by IFNT in vivo. In addition, a number of genes that are directly regulated by short term exposure to IFNT in vivo are differentially expressed on day 18 following estrus detection in the blood of postpartum dairy cows depending on their pregnancy status.

Acute dietary restriction in heifers alters expression of genes regulating exposure and response to gonadotrophins and IGF in dominant follicles

Dietary restriction in growing cattle and severe negative energy balance in lactating cows have been associated with altered gonadotropin secretion, reduced follicle diameter, reduced circulating oestradiol concentrations and anovulation. Therefore, we hypothesised that acute dietary restriction would influence the fate and function of the dominant follicle by altering the expression for genes regulating gonadotrophin and IGF response in ovarian follicles. Newly selected dominant follicles were collected 7-8 days after prostaglandin F(2α) (PGF) administration from heifers (n=25) that were individually fed a diet supplying 1.2 maintenance (M; control, n=8) or 0.4 M (restricted, n=17) for a total duration of 18-19 days. Heifers within 0.4 M were ovulatory (n=11) or anovulatory (n=6) depending on whether the dominant follicle present at PGF ovulated or became atretic following luteolysis. Control animals were all ovulatory. Acute dietary restriction decreased IGF-I (P<0.001) and insulin (P<0.05) in circulation; oestradiol (P<0.01) and IGF-I (P<0.01) in follicular fluid; and mRNA for FSHR (P<0.01) in granulosa cells but increased mRNA for IGFBP2 (P<0.05) in theca cells of the newly selected dominant follicle. However, this only led to anovulation when dietary restriction also decreased mRNA for CYP19A1 (P<0.05), IGF2 (P<0.01) and IGF1R (P<0.05) in granulosa cells and LHCGR (P<0.05) in theca cells of follicles collected from heifers fed 0.4 M. These results suggest that the catabolic environment induced by dietary restriction may ultimately cause anovulation by reducing oestradiol synthesis, FSH-responsiveness and IGF signaling in granulosa, and LH-responsiveness in theca cells of dominant follicles.

Effect of follicular aspiration just before ovulation on corpus luteum characteristics, circulating progesterone concentrations and uterine receptivity in single-ovulating and superstimulated heifers

The aim of this study was to investigate, in unstimulated and superstimulated heifers, the effect of follicle aspiration just before ovulation on corpus luteum (CL) development, circulating progesterone (P4) concentrations and the ability of the uterus to support embryo development. Following follicle aspiration or ovulation timed from GNRH administration, CL development was assessed by daily ultrasonography, and CL function was assessed in terms of the capacity to produce P4 and the expression of genes involved in steroidogenesis in luteal tissue. The capacity of the uterine environment to support conceptus development was assessed following transfer and recovery of in vitro-produced embryos. Follicular aspiration just before the expected time of ovulation leads to a significant reduction in CL diameter, CL area and area of luteal tissue. This was associated with a decrease in circulating P4 in both unstimulated and superstimulated heifers. Follicle aspiration leads to a reduction in conceptus length and area on day 14 in unstimulated heifers only. Follicle aspiration leads to a reduction in the expression of LHCGR in luteal tissue from unstimulated heifers compared with those in which the CL formed after ovulation. Superstimulation significantly reduced the expression of STAR in luteal tissue in both ovulated and follicle-aspirated heifers. In conclusion, in stimulated and unstimulated heifers, aspiration of the preovulatory dominant follicle(s) just before expected ovulation interferes with the subsequent formation and function of the CL, in terms of size and P4 output and this, in turn, is associated with a reduced capacity of the uterus to support conceptus elongation in unstimulated heifers.

Effect of the metabolic environment at key stages of follicle development in cattle: focus on steroid biosynthesis

Cellular mechanisms that contribute to low estradiol concentrations produced by the preovulatory ovarian follicle in cattle with a compromised metabolic status are largely unknown. To gain insight into the main metabolic mechanisms affecting preovulatory follicle function, two different animal models were used. Experiment 1 compared Holstein-Friesian nonlactating heifers (n = 17) and lactating cows (n = 16) at three stages of preovulatory follicle development: 1) newly selected dominant follicle in the luteal phase (Selection), 2) follicular phase before the LH surge (Differentiation), and 3) preovulatory phase after the LH surge (Luteinization). Experiment 2 compared newly selected dominant follicles in the luteal phase in beef heifers fed a diet of 1.2 times maintenance (M, n = 8) or 0.4 M (n = 11). Lactating cows and 0.4 M beef heifers had higher concentrations of β-hydroxybutyrate, and lower concentrations of glucose, insulin, and IGF-I compared with dairy heifers and 1.2 M beef heifers, respectively. In lactating cows this altered metabolic environment was associated with reduced dominant follicle estradiol and progesterone synthesis during Differentiation and Luteinization, respectively, and in 0.4 M beef heifers with reduced dominant follicle estradiol synthesis. Using a combination of RNA sequencing, Ingenuity Pathway Analysis, and qRT-PCR validation, we identified several important molecular markers involved in steroid biosynthesis, such as the expression of steroidogenic acute regulatory protein (STAR) within developing dominant follicles, to be downregulated by the catabolic state. Based on this, we propose that the adverse metabolic environment caused by lactation or nutritional restriction decreases preovulatory follicle function mainly by affecting cholesterol transport into the mitochondria to initiate steroidogenesis.

Effects of human chorionic gonadotrophin administration on Day 5 after oestrus on corpus luteum characteristics, circulating progesterone and conceptus elongation in cattle

The aim of the present study was to test the hypothesis that elevated concentrations of progesterone (P4) resulting from the induction of an accessory corpus luteum (CL) by human chorionic gonadotrophin (hCG) administration on Day 5 after oestrus would lead to advanced conceptus elongation on Day 14 following embryo transfer on Day 7. The oestrous cycles of cross-bred beef heifers were synchronised and animals were randomly assigned to receive either of two treatments: (1) intramuscular injection of 3000 IU hCG on Day 5 after oestrus (n = 14); or (2) intramuscular injection of saline on Day 5 after oestrus (n = 13). Ovaries were scanned daily by transrectal ultrasonography to assess CL development. Serum concentrations of P4 were determined from daily blood samples collected from the jugular vein. In vitro-produced bovine blastocysts were transferred to synchronised recipients on Day 7 after oestrus (n = 15 blastocysts per recipient). Heifers were killed on Day 14 after oestrus and the uterus was flushed to recover the embryos. Injection of hCG on Day 5 induced ovulation of the dominant follicle in all treated heifers and increased the total area of luteal tissue on the ovary, which was associated with a significant increase (P < 0.001) in serum concentrations of P4 from Day 7 to Day 14. Positive associations were detected between circulating P4 with CL area (within-day correlations ranging from r = 0.45 to r = 0.67) and total area of luteal tissue (within-day correlations ranging from r = 0.65 to r = 0.86) Administration of hCG did not affect the proportion of Day 14 conceptuses recovered. However, compared with the control group, hCG-treated heifers had increased conceptus length (3.91 ± 1.23 vs 5.57 ± 1.02 mm, respectively; P = 0.06), width (1.00 ± 0.06 vs 1.45 ± 0.05 mm, respectively; P = 0.002) and area (5.71 ± 0.97 vs 8.31 ± 0.83, respectively; P = 0.02). Although numerically greater, mean interferon-τ (IFNT) production in vitro did not differ significantly (P = 0.54) between embryos recovered from hCG-treated and control heifers. In contrast, there was a strong positive correlation between individual embryo length (r = 0.76; P < 0.001) and individual embryo area (r = 0.72; P < 0.001) and IFNT production. In conclusion, administration of hCG on Day 5 after oestrus resulted in the formation of an accessory CL and hypertrophy of the original CL, the result of which was an increase in P4 concentrations from Day 7 onwards. These elevated P4 concentrations were associated with an increased conceptus area. Furthermore, conceptus size was highly correlated with IFNT secretion in vitro.

85 EFFECT OF FOLLICULAR ASPIRATION JUST PRIOR TO OVULATION ON CORPUS LUTEUM CHARACTERISTICS, CIRCULATING PROGESTERONE CONCENTRATIONS AND UTERINE RECEPTIVITY IN SINGLE-OVULATING BEEF HEIFERS

Progesterone (P4) has a crucial impact on the transcriptome of the uterine endometrium and the preparation of the uterus to support implantation. The aim of this study was to investigate the effect of follicle aspiration just before ovulation on corpus luteum (CL) development, circulating P4 concentrations and the ability of the uterus to support embryo development and conceptus elongation. We tested the hypothesis that the unavoidable loss of follicular fluid and some granulosa cells during aspiration of the preovulatory follicle would compromise the development and function of the developing CL and that this would be associated with reduced P4 and a poorer uterine environment. Oestrous cycles of crossbred beef heifers were synchronized using an 8-day CIDR treatment with administration of a prostaglandin F2α analogue on the day before CIDR removal to ensure CL regression. Heifers were checked for signs of oestrus 4 times per day commencing 30 h after CIDR withdrawal and only those recorded in standing oestrus (Day 0, n = 20) were used. All heifers received a gonadotropin-releasing hormone agonist (0.01 mg buserelin) 48 h after CIDR removal to induce an LH surge. Half of the animals underwent follicle aspiration 20 h later, while the remainder underwent ovulation. Daily transrectal ultrasonography was carried out from Day 3 to 13 to record CL development. Daily blood samples were collected from Day 0 to 14 for circulating P4 concentrations. To test the ability of the uterus to support embryo development and conceptus elongation, Day 7 in vitro-produced blastocysts were transferred to the uteri of synchronised recipients (7 to 10 blastocysts per recipient). All recipients were slaughtered on Day 14 to assess embryo survival and conceptus size. CL diameter and CL area were significantly reduced in the follicle aspirated group compared with controls from Day 6 onwards (P ≤ 0.05). Similarly, at slaughter on Day 14, CL weight (4.17 ± 0.48 vs 7.05 ± 1.65 mm), diameter (19.89 ± 1.35 vs 24.64 ± 2.07 mm) and area (321.94 ± 45.01 vs 510.18 ± 69.41 mm2) were lower in aspirated heifers (P ≤ 0.05). Circulating P4 concentrations were lower at all time points from Day 3 to Day 14 but were only significantly lower from Day 12 onwards (P ≤ 0.05). Conceptus length (2.08 ± 0.29, n = 56 vs 4.55 ± 0.78 mm, n = 45) and area (2.52 ± 0.39 vs 5.61 ± 1.12 mm2) were lower (P ≤ 0.05) in heifers undergoing follicular aspiration compared with those undergoing ovulation. In conclusion, aspiration of the preovulatory dominant follicle just before expected ovulation was associated with a compromised CL in terms of size and P4 output and this, in turn, was associated with a reduced capacity of the uterus to support the initiation of conceptus elongation. Supported by Science Foundation Ireland (07/SRC/B1156).

Temporal changes in endometrial gene expression and protein localization of members of the IGF family in cattle: effects of progesterone and pregnancy

In the study presented, the hypothesis that ligands of the insulin-like growth factor (IGF) family, as well as their binding proteins (BPs), are temporally regulated and are altered by elevated progesterone (P4) and/or pregnancy was tested. Heifers detected in standing estrus following synchronization (n = 210, day 0), were artificially inseminated (n = 140) or left as noninseminated cyclic controls (n = 70). On day 3, half of each group were randomly assigned to receive a P4-releasing intravaginal device resulting in four treatment groups, pregnant and cyclic heifers with high and normal P4 concentrations on either day 5, 7, 13, or 16 of the estrous cycle/early pregnancy. Quantitative real-time PCR and immunohistochemistry were performed on endometrial homogenate and uterine cross sections to measure transcript abundance and protein localization respectively (n = 5 per treatment per time point). No effect of day, treatment, or their interactions was observed for IGF2, IGFBP4, and -5 (P > 0.05). IGF1 and IGFBP6 expression decreased, while IGF1R and IGFBP2 expression increased (P < 0.05) as the days of the cycle or pregnancy progressed. The expression of IGFBP2 was increased by elevated P4; in addition, localization of both IGF2 and IGFBP2 protein in the luminal and superficial glandular epithelium displayed a P4 × day interaction. In conclusion it is proposed that decreased IGF1 and IGFBP6 expression with a coordinate increase in IGF1R and IGFBP2 as the estrous cycle/early pregnancy progresses, along with other factors, are required to establish a uterine environment that promotes the growth and development of the conceptus prior to implantation. In addition, the increased protein abundance of both IGF2 and IGFBP2 observed in heifers supplemented with P4 contributes to the enhanced conceptus elongation observed in this model.

Endometrial expression of progesterone-induced blocking factor and galectins-1, -3, -9, and -3 binding protein in the luteal phase and early pregnancy in cattle

Progesterone-induced blocking factor (PIBF) and galectins modulate the maternal immune response during pregnancy. We hypothesized that the relative transcript abundance of the above genes would be different during the luteal phase/early pregnancy and would be affected by progesterone supplementation. To further test this, hypothesis protein expression analyses were carried out to evaluate the abundance and localization of LGALS9 and PIBF. Following estrus synchronization, heifers were inseminated ( n = 140) or not ( n = 70). Half the heifers in each status (cyclic or potentially pregnant) were randomly assigned to receive a progesterone-releasing intravaginal device (PRID) on day 3 after estrus, which elevated progesterone concentrations from day 3.5 to 8 ( P < 0.05), resulting in four treatment groups: cyclic and pregnant heifers, each with normal and high progesterone. After confirmation of pregnancy status in inseminated animals, uterine tissue was collected on days 5, 7, 13, or 16 of the luteal phase of the cycle/pregnancy. Gene and protein expression was determined using Q-RT-PCR and IHC, respectively, on 5 heifers per treatment per time point (i.e., 80 in total). Progesterone concentrations did not affect expression of any of the genes ( P > 0.05). LGALS9 and LGALS3BP were expressed at low levels in both cyclic and pregnant endometria until day 13. On day 16, expression increased only in the pregnant heifers ( P < 0.0001). LGALS1 and LGALS3 decreased on day 7 ( P < 0.0001) and remained low until day 16. Pregnancy had no effect on the expression of LGALS1, LGALS3, and PIBF. Additionally, LGALS9 and PIBF proteins were expressed in distinct uterine cell types. These results indicate that the galectins may be involved in uterine receptivity and/or implantation in heifers.

Transcriptome changes at the initiation of elongation in the bovine conceptus

The majority of embryonic loss in cattle occurs before maternal recognition of pregnancy, at around Day 16 postconception. The origin of the embryo can have a significant impact on the dynamics of embryo mortality. The aim of this study was to examine the temporal changes in transcriptional profile as the embryo develops from a spherical blastocyst on Day 7 to an ovoid conceptus at the initiation of elongation on Day 13 and to highlight differences in these temporal gene expression dynamics between in vivo- and in vitro-derived blastocysts that may be associated with embryonic survival/mortality using the bovine Affymetrix microarray. All embryos were produced either in vitro by in vitro fertilization or in vivo by superovulation. A proportion of Day 7 blastocysts were snap frozen, and the remainder were transferred (n = 10 per recipient) to synchronized heifers, recovered on Day 13, and snap frozen individually. Three pools of Day 7 blastocysts (n = 25 per pool) and Day 13 conceptuses (n = 5 per pool) were used for microarray analysis. In Day 7 blastocysts, 50 genes were found to be differentially expressed (P < 0.05), of which 19 were up-regulated and 31 down-regulated in the in vivo compared to in vitro embryos. In Day 13 conceptuses, 288 genes were found to be differentially expressed (P < 0.05), of which 133 were up-regulated and 155 down-regulated in the in vivo compared to in vitro embryos. The comparison between Day 7 and Day 13 embryos revealed significant temporal changes in transcript profile with 1806 and 909 transcripts differentially expressed in the in vitro- and in vivo-derived embryos, respectively. Across the three array comparisons between Day 7 and Day 13 embryos, 444 genes were consistently exclusively present in the in vivo embryos, whereas 1341 were exclusively present in the in vitro embryos. Regardless of the origin of the embryo, 465 differentially expressed genes between Day 7 and 13 were common to both in vivo- and in vitro-derived embryos; these genes are likely critical for the transition between the blastocyst (Day 7) and ovoid conceptus (Day 13) stages of embryo development. In order to validate the microarray findings, differences in the expression of six genes (CYP51A1, FADS1, TDGF1, HABP2, APOA2, and SLC12A2) were confirmed by quantitative real-time PCR on in vivo- and in vitro-derived embryos on Day 7 and Day 13 using independent samples from those used for the microarray. Subsequent mapping of these differentially expressed genes into relevant functional groups and pathways identified important pathways involved in conceptus elongation in cattle. In conclusion, this analysis has identified genes and pathways crucial for the transition from a spherical blastocyst to an ovoid conceptus as well as those uniquely associated with a greater likelihood of embryonic survival (those unique to in vivo embryos) or loss (those unique to in vitro embryos).

200 IN VITRO EMBRYO PRODUCTION IS ASSOCIATED WITH DISTINCT ALTERATIONS IN THE TRANSCRIPTOME BETWEEN THE BLASTOCYST STAGE AND THE INITIATION OF ELONGATION IN CATTLE

The majority of embryonic loss in cattle occurs before maternal recognition of pregnancy around Day 16 postconception. The origin of the embryo can have a significant impact on the dynamics of embryo mortality. The aim of the present study was to compare transcript profiles between Day 7 (spherical blastocyst) and Day 13 (ovoid conceptus) bovine embryos derived in vitro or in vivo using the bovine Affymetrix microarray. Subsequent mapping of these differentially expressed genes (DEG) into relevant functional groups and pathways using ingenuity pathway analysis would identify the most important pathways involved in conceptus elongation in cattle. All embryos were produced either in vitro or in vivo by superovulation. A proportion of Day 7 blastocysts were snap frozen and the remainder were transferred (n = 10 per recipient) to synchronized heifers, recovered on Day 13, and snap frozen individually. Three pools of Day 7 blastocysts (n = 25 per pool) and Day 13 conceptuses (n = 5 per pool) were used for microarray analysis. A total of 909 and 1806 transcripts were differentially expressed between Day 7 and 13 in in vivo- and in vitro-derived embryos, respectively, of which a core of 465 transcripts was common to both groups. These 465 genes, likely to be crucial for the transition from blastocyst to the initiation of elongation, were associated with 5 canonical pathways, including interleukin (IL)-6 and IL-10 signalling, the endoplasmic reticulum stress pathway, and nitrogen metabolism. The top networks identified genes associated with 1) cellular development, lipid metabolism, and small molecular biochemistry; 2) cell-to-cell signaling; and 3) amino acid metabolism, including transcripts such as MYC, SLC25A12, HSPH1, LXN, ALDH18A1, PMP22, PEG3, CDH2, and Hsp70, which were up-regulated in the conceptus on Day 13. The top canonical pathways among the 444 DEG unique to in vivo embryos were 1) glycerolipid metabolism, 2) steroid biosynthesis, and 3) acute phase response signalling. One of the interaction networks identified was associated with cardiovascular system development and function, gene expression, and organismal development, including transcripts of proteins such as laminins and claudins, which are important for cell communication and morphogenesis during embryonic development. Among the 1341 DEG unique to in vitro-produced embryos, the top pathways were 1) glycerophospholipid metabolism, 2) IL-6 signalling, and 3) endothelial-1 signalling, whereas one of the interaction networks identified was associated with hematological disease, organismal injury, and abnormalities and cellular development, including POU5F1, a transcription factor known to bind to DNA and activate or repress transcription of several genes important for early embryonic development. In conclusion, this analysis has identified genes and pathways crucial to the transition from a spherical blastocyst to an ovoid conceptus as well as those uniquely associated with a greater likelihood of embryonic survival (those unique to in vivo embryos) or loss (those unique to in vitro embryos).

115 EXPRESSION OF RADICAL S-ADENOSYL METHIONINE DOMAIN CONTAINING-2 (RSAD2) AND TRANSFORMING GROWTH FACTOR β (TGF-β) IN BOVINE PERIPHERAL BLOOD MONONUCLEAR CELLS DURING PREGNANCY: IDENTIFICATION OF POTENTIAL BIOMARKERS TO DETERMINE PREGNANCY STATUS

During the bovine peri-implantation period, immune cells are exposed to endocrine and paracrine signals, which support feto-placental development. Recent studies in cattle have shown that the antiviral factor Mx2, known to be up-regulated by conceptus-derived interferon-τ in pregnancy, is detected in peripheral blood mononuclear cells (PBMC) and can be used for pregnancy detection on Day 18. The objectives of the current study were to correlate mRNA expression levels of pregnancy associated factors and immune modulators RSAD2 (radical S-adenosyl methionine domain containing-2) and TGF-β (transforming growth factor β) in circulating PBMCs, with pregnancy status in dairy cows and heifers. Holstein-Friesian heifers (n = 12) and lactating dairy cows (n = 17) were synchronised to estrus and artificially inseminated (bred) or not (non bred, n = 4). Blood samples were collected on Day 0 (day of AI or estrus), 5, 7, 13, 16, 20, and 25 for PBMC isolation. Pregnancy was diagnosed retrospectively by transrectal ultrasonography at Days 30 and 60 after breeding. The relative quantification of RSAD2 and TGF-β transcript abundance, analysed by qPCR, was normalised against PPIA and calculated according to the relative standard curve method. Data from duplicates were pooled, and a mixed model was run on the pooled Cq values for each stage. Genes were considered as differentially expressed if the mixed model P value was <0.05. RSAD2 mRNA abundance was 2-fold higher in pregnant heifers compared with non-bred heifers on Day 20 (P < 0.01) and Day 25 (P < 0.03) post AI. Likewise, RSAD2 mRNA expression was greater (2.25 fold) in pregnant heifers compared with heifers that were inseminated but not pregnant (P < 0.007). In contrast, RSAD2 expression was not significantly different in pregnant cows compared to non-bred or bred but non-pregnant cows. TGF-β mRNA abundance was significantly lower in both pregnant cows (3.5-fold, P < 0.04) and pregnant heifers (4.5-fold, P < 0.01) compared to non-bred animals as early as Day 13. This suppression of expression was maintained until Day 20 in heifers (3.9-fold, P < 0.02). In addition, PBMC TGF-β mRNA expression was lower in pregnant cows compared with bred non-pregnant cows (1.65-fold, P < 0.06). In conclusion, Day 20 PBMC RSAD2 expression may be a useful predictor of pregnancy maintenance in dairy heifers. However, decreased TGF-β expression as early as Day 13 appears to be a more powerful indicator of the presence of a viable embryo in both dairy heifers and cows and may play a role in the establishment and maintenance of pregnancy through the restriction of monocyte recruitment or activation during the time of maternal recognition of pregnancy. Research supported by Science Foundation Ireland (PICA-B813)

Changes in the endometrial transcriptome during the bovine estrous cycle: effect of low circulating progesterone and consequences for conceptus elongation

In cattle, elevated concentrations of circulating progesterone (P4) in the immediate postconception period are associated with advanced conceptus development, while low P4 is implicated as a causative factor in low pregnancy rates observed in dairy cows. This study aimed to: 1) describe the transcriptional changes that occur in the bovine endometrium during the estrous cycle, 2) determine how elevated P4 affects these changes, 3) identify if low P4 alters the expression of these genes, and 4) assess the impact that low P4 has on conceptus development. Relatively few differences occurred in endometrial gene expression during the early luteal phase of the estrous cycle (Day 5 vs. 7), but comparison of endometria from more distant stages of the luteal phase (Day 7 vs. 13) revealed large transcriptional changes, which were significantly altered by exogenous supplementation of P4. Induction of low circulating P4 altered the normal temporal changes in gene expression, and these changes were coordinate with a delay in the down-regulation of the PGR from the LE and GE. Altered endometrial gene expression induced by low P4 was associated with a reduced capacity of the uterus to support conceptus development after embryo transfer on Day 7. In conclusion, the present study provides clear evidence that the temporal changes in the transcriptome of the endometrium of cyclic heifers are sensitive to circulating P4 concentrations in the first few days after estrus. Under low P4 conditions, a suboptimal uterine environment with reduced ability to support conceptus elongation is observed.

The effect of elevated progesterone and pregnancy status on mRNA expression and localisation of progesterone and oestrogen receptors in the bovine uterus

To investigate the effects of pregnancy or post-ovulatory progesterone (P4) supplementation on the expression of oestrogen and P4 receptors (ESRs and PGRs) in the bovine uterus, heifers (n=263) were randomly assigned to the following treatments: i) cyclic, normal P4; ii) cyclic, high P4; iii) pregnant, normal P4; and iv) pregnant, high P4 on days 5, 7, 13 and 16 of pregnancy/oestrous cycle. Elevated P4 was achieved through P4-releasing intravaginal device insertion on day 3 after oestrus, resulting in increased concentrations from day 3.5 to 8 (P<0.05) in the high groups than in the normal groups. Irrespective of treatment, PGR and ESR1 mRNA expressions were highest on days 5 and 7 and decreased on day 13 (P<0.05), while ESR2 mRNA expression increased on day 7 (P<0.05) and similar levels were maintained within the normal P4 groups subsequently. Expression in the high P4 groups decreased on day 13 (P<0.05). PGR-AB and PGR-B protein expressions were high in the luminal and superficial glands on days 5 and 7, but by day 13, expression had declined to very low or undetectable levels and high P4 concentration tended to decrease or decreased significantly (P<0.05) the expression in these regions on days 5 and 7. ESR1 protein expression was high, with no treatment effect. ESR2 protein was also highly expressed, with no clear effect of treatment. In conclusion, early post-ovulatory P4 supplementation advances the disappearance of PGR protein from the luminal epithelium on days 5 and 7, and decreases ESR2 mRNA expression during the mid-luteal phase, but has no effect on PGR or ESR1 mRNA expression.