Screening and Identification of Differential Ovarian Proteins before and after Induced Ovulation via Seminal Plasma in Bactrian Camels

Camelidae are induced ovulators whose ovulation is tightly regulated by multiple factors. Understanding the biological mechanisms underlying follicular development, hormone secretion, and ovulation requires investigating the potential molecular pathways involved. However, little is known about these pathways in Bactrian camels. To screen and identify candidate biomarkers after inducing ovulation, this study performed comprehensive proteomic and molecular biological analyses of the ovaries from two camel groups (n = 6). We identified 5075 expressed ovarian proteins, of which 404 were differentially expressed (264 upregulated, 140 downregulated) (p < 0.05 or p < 0.01), in samples from plasma-induced versus control camels. Gene ontology annotation identified the potential functions of the differentially expressed proteins (DEPs). These results validated the differential expression for a subset of these proteins using Western blot (p < 0.05) and immunofluorescence staining. Three DEPs (FST, NR5A1, and PRL) were involved in neurochemical signal transduction, as well as endocrine and reproductive hormone regulatory processes. The Kyoto Encyclopedia of Genes and Genomes analysis indicated the involvement of several pathways, including the calcium, cAMP, gonadotropin-releasing hormone, MAPK, and neuroactive ligand–receptor signaling pathways, suggesting that induced ovulation depends on the hypothalamic–pituitary–ovarian axis. Identifying these candidate biomarkers enables a better understanding of Bactrian camel reproduction. Ovarian proteomic profiling and the measurement of selected proteins using more targeted methods is a promising approach for studying induced-ovulation mechanisms.

Correlation between Pre-Ovulatory Follicle Diameter and Follicular Fluid Metabolome Profiles in Lactating Beef Cows

Induced ovulation of small pre-ovulatory follicles reduced pregnancy rates, embryo survival, day seven embryo quality, and successful embryo cleavage in beef cows undergoing fixed-time artificial insemination. RNA-sequencing of oocytes and associated cumulus cells collected from pre-ovulatory follicles 23 h after gonadotropin-releasing hormone (GnRH) administration to induce the pre-ovulatory gonadotropin surge suggested reduced capacity for glucose metabolism in cumulus cells of follicles ≤11.7 mm. We hypothesized that the follicular fluid metabolome influences metabolic capacity of the cumulus-oocyte complex and contributes to reduced embryo cleavage and quality grade observed following induced ovulation of small follicles. Therefore, we performed a study to determine the correlation between pre-ovulatory follicle diameter and follicular fluid metabolome profiles in lactating beef cows (Angus, n = 130). We synchronized the development of a pre-ovulatory follicle and collected the follicular contents approximately 20 h after GnRH administration. We then performed ultra-high performance liquid chromatography—high resolution mass spectrometry (UHPLC-HRMS) metabolomic studies on 43 follicular fluid samples and identified 38 metabolites within pre-ovulatory follicles of increasing size. We detected 18 metabolites with a significant, positive correlation to follicle diameter. Individual and pathway enrichment analysis of significantly correlated metabolites suggest that altered glucose and amino acid metabolism likely contribute to reduced developmental competence of oocytes when small pre-ovulatory follicles undergo induced ovulation.

P–629 Is spontaneous ovulation better than induced ovulation for frozen-thawed embryo transfer cycle?

Study question Between spontaneous ovulation (SPO) and induced ovulation (INO) comparing clinical pregnancy rate and ongoing pregnancy rate for frozen-thawed embryo transfer (FET) cycle, which is better? Summary answer Both spontaneous ovulation and induced ovulation protocols showed no significant difference in clinical pregnancy rates and ongoing pregnancy rates. What is known already Recent practice worldwide is moving towards elective freezing of all embryos and subsequent frozen-thawed transfer, both for a perceived higher pregnancy rate as well as the significant reduction of ovarian hyperstimulation. The timing of FET can be determined by either detecting the spontaneous Luteinizing Hormone surge (SPO group) or by the administration of hCG (INO group). There is still an ongoing debate to determine which is the best protocol for frozen-thawed embryo transfer in the non-hormone replacement therapy (non-HRT) cycle. Study design, size, duration This retrospective study included 500 FET cycles for patients who had regular menses between June 2017 and June 2020. The FET cycles were grouped by type as follows: SPO (n = 281) and INO (n = 219). The primary outcome was the clinical pregnancy rate and the secondary outcome was ongoing pregnancy rate. Ongoing pregnancy is defined as a viable intrauterine pregnancy at 12 weeks of gestation confirmed on an ultrasound scan. Participants/materials, setting, methods This study was conducted in a single IVF centre. Vitrification was used as the cryopreservation method. To standardize outcome measures, only patients having single blastocyst transfer and aged under 38 years old were included. The average age of the patient was 32.9. Gamete donation, embryo donation, pre-implantation testing and assisted hatching cycles were also excluded from the analysis. Categorical data were analysed using Chi-square test SPSS version 25. Main results and the role of chance Clinical pregnancy rate for SPO group was 54.8% (154/281) versus 52.9% (116/219) in INO group. Even though clinical pregnancy rate was higher in SPO group as compared to INO group, it did not reach significance level (ꭓ2 = 0.17, p = 0.68). As all patients had single blastocyst transferred, the implantation rate was the same as clinical pregnancy rate. Ongoing pregnancy rate was also found higher in SPO group as compared to INO group (135/281, 48.0% and 97/219, 44.3% respectively) but again failed to reach significance level (ꭓ2 = 0.70, p = 0.40). Limitations, reasons for caution The retrospective nature of the study and therefore, the analysis was not adjusted for confounding factors such as blastocyst grading, etiology of infertility, and ethnicity of patients. Wider implications of the findings: In natural cycle, both spontaneous ovulation and induced ovulation protocols had the same pregnancy outcomes for frozen-thawed embryo transfer. However, induced ovulation can facilitate in scheduling FET timing to avoid weekends and public holidays, if necessary. Trial registration number Not applicable

Differential Transcript Profiles in Cumulus-Oocyte Complexes Originating from Pre-Ovulatory Follicles of Varied Physiological Maturity in Beef Cows

Small dominant follicle diameter at induced ovulation, but not at spontaneous ovulation, decreased pregnancy rate, fertilization rate, and day seven embryo quality in beef cows. We hypothesized that the physiological status of the follicle at GnRH-induced ovulation has a direct effect on the transcriptome of the Cumulus-Oocyte complex, thereby affecting oocyte competence and subsequent embryo development. The objective of this study was to determine if the transcriptome of oocytes and associated cumulus cells (CC) differed among small (≤11.7 mm) and large follicles (≥12.7 mm) exposed to a GnRH-induced gonadotropin surge and follicles (11.7–14.0 mm) exposed to an endogenous gonadotropin surge (spontaneous follicles). RNA sequencing data, from pools of four oocytes or their corresponding CC, revealed 69, 94, and 83 differentially expressed gene transcripts (DEG) among oocyte pools from small versus large, small versus spontaneous, and large versus spontaneous follicle classifications, respectively. An additional 128, 98, and 80 DEG were identified among small versus large, small versus spontaneous, and large versus spontaneous follicle CC pools, respectively. The biological pathway “oxidative phosphorylation” was significantly enriched with DEG from small versus spontaneous follicle oocyte pools (FDR < 0.01); whereas the glycolytic pathway was significantly enriched with DEG from CC pools obtained from large versus small follicles (FDR < 0.01). These findings collectively suggest that altered carbohydrate metabolism within the Cumulus-Oocyte complex likely contributes to the decreased competency of oocytes from small pre-ovulatory follicles exposed to an exogenous GnRH-induced gonadotropin surge.

Screening and Identification of Ovulation-Inducing Regulatory Factors in Bactrian Camel

Background: Camelidae are inducing ovulators, ovulation is tightly regulated by multiple factors, and understanding the biological mechanisms underlying follicular development, hormone secretion and ovulation requires investigation of the potential molecular pathways. However, little is known about the pathways of these factors in the camel. To screening and identification candidate biomarkers after inducing ovulators in ovary.Methods: In this paper, the quantitative proteomics method iTRAQ analysis technology was used to analyze the proteomic differences of ovarian before and after induced ovulation in Bactrian camels. The differentially expressed protein was validated by Western blot, qRT-PCR and Immunofluorescence staining analysis.Results: A total of 5,075 ovarian expressed proteins were detected, and 404 proteins were differentially expressed (264 up-regulated, 140 down-regulated) in samples from treated versus control camels. Gene ontology annotation identified potential functions of the differentially expressed proteins (DEPs). We validated the differential expression for a subset of these proteins using western blotting and immunofluorescence staining. Three DEPs (FST, NR5A1 and PRL) were involved in neurochemical signal transduction, endocrine and reproductive hormones regulatory processes. KEGG analysis indicated the involvement of several pathways, such as calcium, cAMP, gonadotropin-releasing hormone, MAPK, and neuroactive ligand-receptor signaling pathways, further suggesting that the induced ovulation process depends on the hypothalamic-pituitary-ovarian axis. Conclusions: This study is the first to perform quantitative proteomic investigation by iTRAQ labeling and LC-MS/MS to identify differentially expressed proteins induced ovulation in Bactrian camels. Our study has revealed distinct molecular functions and metabolic pathways that are active during reproduction in Bactrian camels. These results have demonstrated the pivotal role played by 3 DEPs in the modulation and activation of the reproductive axis during induced ovulation in the Bactrian camel, followed by the measurement of selected proteins using more targeted methods, offers a promising approach for studying potential mechanism of ovary development and ovulation.