Proteomic analysis of mare follicular fluid during late follicle development

Bacterial endometritis-induced changes in the endometrial proteome in mares: Potential uterine biomarker for bacterial endometritis

Equine endometritis is one of the main causes of subfertility in the mare. Unraveling the molecular mechanisms involved in this condition and pinpointing proteins with biomarker potential could be crucial in both diagnosing and treating this condition. This study aimed to identify the endometritis-induced changes in the endometrial proteome in mares and to elucidate potential biological processes in which these proteins may be involved. Secondly, biomarkers related to bacterial endometritis (BE) in mares were identified. Uterine lavage fluid samples were collected from 28 mares (14 healthy: negative cytology and culture, and no clinical signs and 14 mares with endometritis: positive cytology and culture, in addition to clinical signs). Proteomic analysis was performed with a UHPLC-MS/MS system and bioinformatic analysis was carried out using Qlucore Omics Explorer. Gene Ontology enrichment and pathway analysis (PANTHER and KEGG) of the uterine proteome were performed to identify active biological pathways in enriched proteins from each group. Quantitative analysis revealed 38 proteins differentially abundant in endometritis mares when compared to healthy mares (fold changes >4.25, and q-value = 0.002). The proteins upregulated in the secretome of mares with BE were involved in biological processes related to the generation of energy and REDOX regulation and to the defense response to bacterium. A total of 24 biomarkers for BE were identified using the biomarker workbench algorithm. Some of the proteins identified were related to the innate immune system such as isoforms of histones H2A and H2B involvement in neutrophil extracellular trap (NET) formation, complement C3a, or gelsolin and profilin, two actin-binding proteins which are essential for dynamic remodeling of the actin cytoskeleton during cell migration. The other group of biomarkers were three known antimicrobial peptides (lysosome, equine cathelicidin 2 and myeloperoxidase (MPO)) and two uncharacterized proteins with a high homology with cathelicidin families. Findings in this study provide the first evidence that innate immune cells in the equine endometrium undergo reprogramming of metabolic pathways similar to the Warburg effect during activation. In addition, biomarkers of BE in uterine fluid of mares including the new proteins identified, as well as other antimicrobial peptides already known, offer future lines of research for alternative treatments to antibiotics.

Proteome and metabolomic profile of Mongolian horse follicular fluid during follicle development

During follicular development, changes in the composition of the follicular fluid are synchronized with the development of oocytes. Our aim was to screen the key factors affecting oocyte maturation and optimize the in vitro culture protocol by understanding the changes of proteins and metabolites in follicular fluid. Follicles are divided into three groups according to their diameter (small follicle fluid (SFF): 10 mm < d < 20 mm; medium follicle fluid (MFF): 20 mm < d < 30 mm; large follicle fluid (LFF): 30 mm < d). Proteins and metabolites from the follicular fluid were analyzed by mass spectrometry. The results showed that: in LFF vs MFF, 20 differential abundant protein (DAP) and 88 differential abundant metabolites (DAM) were screened out; In SFF vs MFF, 3 DAPs and 65 DAMs were screened out; In MFF vs SFF, 24 DAPs and 35 DAMs were screened out. The analysis of differential proteins and metabolites showed that glycerophosphate hydrolysis decreased during follicular development, and proteins played a major role in metabolism and binding. In addition, DAMs and DAPs are co-enriched in the "linoleic acid metabolism" pathway. Combinatorial analysis reveals the dynamic profile of follicular fluid during follicular development and provides fundation for further exploring the function of follicular fluid in Mongolian horse.

Prolonged follicular dominance is associated with dysregulated proteomic profile of the follicular fluid in Bos indicus cows

Prolonged follicular dominance is one of the conditions associated with disconcerted follicular dynamics that result in substantial economic losses to the farmers through low reproductive efficiency in cattle. Hormonal aberrations associated with prolonged follicular dominance may affect the follicular microenvironment and composition of follicular fluid. The current study focused on proteome changes of follicular fluid in prolonged follicular dominance compared to physiological follicular dominance. Prolonged dominance was induced in Deoni cows (n = 6) by using CIDR (previously used for 7 days) from day 4-8 of estrus, with PGF2 injection on day 6 and day 7 at 12 h intervals. Follicular fluid was collected by ultrasound guided transvaginal follicular aspiration method. Global proteomic analysis of follicular fluid revealed 217 proteins in the Deoni cow, with the majority of proteins involved in 21 pathways, 42 molecular functions, and 106 biological processes. Complement and coagulation cascades (22.8%) and cholesterol metabolism (4.68%) were the major pathways in which identified proteins were involved. Comparison of physiological and prolonged dominant follicular fluid revealed differential expression of 26 proteins, of which 15 were upregulated and 11 were downregulated. Proteins involved in complement and coagulation cascades, and vitamin digestion and absorption were found to be dysregulated in PFD. The present study suggests that the expression of proteins involved in inflammation, oocyte metabolism, and ovulation cascade were found to be dysregulated in the follicular fluid of prolonged follicular dominance consequently resulting in delayed ovulation or anovulation.

Low-Abundance Protein Enrichment for Medical Applications: The Involvement of Combinatorial Peptide Library Technique

The discovery of low- and very low-abundance proteins in medical applications is considered a key success factor in various important domains. To reach this category of proteins, it is essential to adopt procedures consisting of the selective enrichment of species that are present at extremely low concentrations. In the past few years pathways towards this objective have been proposed. In this review, a general landscape of the enrichment technology situation is made first with the presentation and the use of combinatorial peptide libraries. Then, a description of this peculiar technology for the identification of early-stage biomarkers for well-known pathologies with concrete examples is given. In another field of medical applications, the determination of host cell protein traces potentially present in recombinant therapeutic proteins, such as antibodies, is discussed along with their potentially deleterious effects on the health of patients on the one hand, and on the stability of these biodrugs on the other hand. Various additional applications of medical interest are disclosed for biological fluids investigations where the target proteins are present at very low concentrations (e.g., protein allergens).

How in vitro maturation changes the proteome of ovine cumulus-oocyte complexes?

The present study evaluated the effects of in vitro maturation (IVM) on the proteome of cumulus-oocyte complexes (COCs) from ewes. Extracted COC proteins were analyzed by LC-MS/MS. Differences in protein abundances (p < 0.05) and functional enrichments in immature versus in vitro-matured COCs were evaluated using bioinformatics tools. There were 2550 proteins identified in the COCs, with 89 and 87 proteins exclusive to immature and mature COCs, respectively. IVM caused downregulation of 84 and upregulation of 34 proteins. Major upregulated proteins in mature COCs were dopey_N domain-containing protein, structural maintenance of chromosomes protein, ubiquitin-like modifier-activating enzyme 2. Main downregulated proteins in mature COCs were immunoglobulin heavy constant mu, inter-alpha-trypsin inhibitor heavy chain 2, alpha-2-macroglobulin. Proteins exclusive to mature COCs and upregulated after IVM related to immune response, complement cascade, vesicle-mediated transport, cell cycle, and extracellular matrix organization. Proteins of immature COCs and downregulated after IVM were linked to metabolic processes, immune response, and complement cascade. KEGG pathways and miRNA-regulated genes attributed to downregulated and mature COC proteins related to complement and coagulation cascades, metabolism, humoral response, and B cell-mediated immunity. Thus, IVM influenced the ovine COC proteome. This knowledge supports the future development of efficient IVM protocols for Ovis aries.

Follicular-fluid proteomics during equine follicle development

The complex composition of the follicular fluid (FF), the intimate proximity to the oocyte, and the continual changes in their composition have a major effect on folliculogenesis and oogenesis. To date, the profiling of FF proteomes during follicle selection, development, and ovulation has not been comprehensively investigated. Therefore, a shotgun proteomics approach and bioinformatics analyses were used to profile the proteomes of equine FF harvested in vivo from follicles at the following development stages: predeviation (18-20 mm), deviation (22-25 mm), postdeviation (26-29 mm), preovulatory (30-35 mm), and impending ovulation. A total of 294 proteins were detected in FF (FDR <1%), corresponding to 65 common proteins and 124, 142, 167, 132, and 142 proteins in the predeviation, deviation, postdeviation, preovulatory, and impending ovulation groups, respectively. The higher expression of properdin and several other proteins belonging to the complement system during the deviation time and ovulation suggested their contribution in the selection of the future dominant follicle and ovulation. Apolipoprotein A-1 and antithrombin-III appeared to be important throughout folliculogenesis. The "complement and coagulation cascades" was the major KEGG pathway across all stages of follicle development. The significant expression of several proteins belonging to the serine-type endopeptidase indicated their likely contribution to follicle and oocyte development. Our data provide an extensive description and functional analyses of the equine FF proteome during follicle selection, development, and ovulation. This information will help improve understanding of the ovarian function and ovulatory dysfunctions and might serve as a reference for future biomarker discovery for oocyte quality assessment.

Differential proteomic analysis demonstrates follicle fluid participate immune reaction and protein translation in yak

Background

Ovarian follicle fluid (FF) as a microenvironment surrounding oocyte plays critical roles in physio-biochemical processes of follicle development and oocyte maturation. It is hypothesized that proteins in yak FF participate in the physio-biochemical pathways. The primary aims of this study were to find differentially expressed proteins (DEPs) between mature and immature FF, and to elucidating functions of the mature and immature FF in yak.

Results

The mature and immature FF samples were obtained from three healthy yaks that were nonpregnant, aged from four to five years, and free from any anatomical reproductive disorders. The FF samples were subjected to mass spectrometry with the isobaric tags for relative and absolute quantification (iTRAQ). The FF samples went through correlation analysis, principle component analysis, and expression pattern analysis based on quantification of the identified proteins. Four hundred sixty-three DEPs between mature and immature FF were identified. The DEPs between the mature and immature FF samples underwent gene ontology (GO), Kyoto encyclopedia of genes and genomes (KEGG), and protein-protein interaction (PPI) analysis. The DEPs highly expressed in the mature FF mainly took parts in the complement and coagulation cascades, defense response, acute-phase response, response to other organism pathways to avoid invasion of exogenous microorganisms. The complement activation pathway contains eight DEPs, namely C2, C5, C6, C7, C9, C4BPA, CFH, and MBL2. The three DEPs, CATHL4, CHGA, and PGLYRP1, take parts in defense response pathway to prevent invasion of exogenetic microorganism. The coagulation cascades pathway involves many coagulation factors, such as F7, F13A1, FGA, FGB, FGG, KLKB1, KNG1, MASP1, SERPINA1, and SERPIND1. While the DEPs highly expressed in the immature FF participated in protein translation, peptide biosynthetic process, DNA conformation change, and DNA geometric change pathways to facilitate follicle development. The translation pathway contains many ribosomal proteins, such as RPL3, RPL5, RPS3, RPS6, and other translation factors, such as EIF3J, EIF4G2, ETF1, MOV10, and NARS. The DNA conformation change and DNA geometric change involve nine DEPs, DDX1, G3BP1, HMGB1, HMGB2, HMGB3, MCM3, MCM5, MCM6, and RUVBL2. Furthermore, the expressed levels of the main DEPs, C2 and SERPIND1, were confirmed by western blot.

Conclusions

The differential proteomics revealed the up-regulated DEPs in mature FF take parts in immunoreaction to prevent invasion of microorganisms and the up-regulated DEPs in immature FF participate in protein synthesis, which may improve our knowledge of the follicular microenvironment and its biological roles for reproductive processes in yak. The DEPs, C2 and SERPIND1, can be considered as protein markers for mature yak follicle.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-03097-0.

Uterine infusion of conceptus fragments changes the protein profile from cyclic mares

This experiment aimed to compare at day seven after ovulation, the protein profile of uterine fluid in cyclic mares with mares infused two days before with Day 13 conceptus fragments. Experimental animals were ten healthy cyclic mares, examined daily to detect ovulation (Day 0) as soon as estrus was confirmed. On day seven, after ovulation, uterine fluid was collected, constituting the Cyclic group (n = 10). The same mares were examined in the second cycle until ovulation was detected. On day five, after ovulation, fragments from a previously collected concepti were infused into each mare's uterus. Two days after infusion, uterine fluid was collected, constituting the Fragment group (n = 10). Two-dimensional electrophoresis technique processed uterine fluid samples. A total of 373 spots were detected. MALDI-TOF/TOF and NanoUHPLC-QTOF mass spectrometry identified twenty spots with differences in abundance between the Cyclic and Fragment group. Thirteen proteins were identified, with different abundance between groups. Identified proteins may be related to embryo-maternal communication, which involves adhesion, nutrition, endothelial cell proliferation, transport, and immunological tolerance. In conclusion, conceptus fragments signalized changes in the protein profile of uterine fluid seven days after ovulation in comparison to the observed at Day 7 in the same cyclic mares.

Protein Cargo of Extracellular Vesicles From Bovine Follicular Fluid and Analysis of Their Origin From Different Ovarian Cells

Follicular fluid (FF) fills the interior portion of the ovarian antral follicle and provides a suitable microenvironment for the growth of the enclosed oocyte through molecular factors that originate from plasma and the secretions of follicular cells. FF contains extracellular nanovesicles (ffEVs), including 30-100-nm membrane-coated exosomes, which carry different types of RNA, proteins, and lipids and directly influence oocyte competence to develop embryo. In the present study, we aimed to characterize the protein cargo of EVs from the FF of 3-6-mm follicles and uncover the origins of ffEVs by assessing expression levels of corresponding mRNAs in bovine follicular cells and oocyte and cell proteomes. Isolated exosome-like ffEVs were 53.6 + 23.3 nm in size and could be internalized by cumulus-oocyte complex. Proteomes of ffEVs and granulosa cells (GC) were assessed using nanoflow liquid chromatography coupled with high-resolution tandem mass spectrometry after the gel fractionation of total proteins. In total, 460 protein isoforms corresponding to 322 unique proteins were identified in ffEVs; among them, 190 were also identified via GC. Gene Ontology terms related to the ribosome, protein and RNA folding, molecular transport, endocytosis, signal transduction, complement and coagulation cascades, apoptosis, and developmental biology pathways, including PI3K-Akt signaling, were significantly enriched features of ffEV proteins. FfEVs contain numerous ribosome and RNA-binding proteins, which may serve to compact different RNAs to regulate gene expression and RNA degradation, and might transfer ribosomal constituents to the oocyte. Majority of genes encoding ffEV proteins expressed at different levels in follicular cells and oocyte, corroborating with numerous proteins, which were reported in bovine oocyte and cumulus cells in other studies thus indicating possible origin of ffEV proteins. The limited abundance of several mRNAs within follicular cells indicated that corresponding ffEV proteins likely originated from circulating exosomes released by other tissues. Analysis of bovine ffEV transcriptome revealed that mRNAs present in ffEV accounted for only 18.3% of detected ffEV proteins. In conclusion, our study revealed numerous proteins within ffEVs, which originated from follicular and other cells. These proteins are likely involved in the maintenance of follicular homeostasis and may affect oocyte competence.

Quantitative proteomic strategies to study reproduction in farm animals: Female reproductive fluids

Reproductive fluids from the female reproductive tract are gaining attention for their potential to support and optimize reproductive processes, including gamete maturation and embryo culture in vitro. Quantitative proteomics is a powerful way to decipher the proteome of reproductive tract fluids and to identify biologically relevant proteins. The present review describes proteomic strategies for analysing female reproductive fluid proteins. In addition, it considers the strategies for the preparation of oviductal, uterine and follicular fluid samples. Finally, it highlights the main results of quantitative proteomic studies, providing insights into the biological processes related to reproductive biology in farm animals. SIGNIFICANCE: Assisted reproductive technologies (ARTs) have become vitally important for farm animal breeding and much effort is going into the optimization and refinement of the techniques. There are also attempts to imitate physiological conditions by adding reproductive fluids or individual fluid proteins to improve in vitro procedures. A detailed knowledge of the reproductive fluid proteomes is indispensable. The present review summarizes the most widely used quantitative proteomic approaches for the analysis of fluids from the female reproductive tract and highlights the potential of quantitative proteomics to delineate reproductive processes and identify candidate proteins for ARTs in farm animals.

The bovine cumulus proteome is influenced by maturation condition and maturational competence of the oocyte

In vitro maturation (IVM) of oocytes has still a negative impact on the developmental competence of oocytes. Therefore, this study analysed the cumulus proteome of individual cumulus-oocyte complexes (COCs) with and without maturational competence, matured under in vivo or in vitro conditions (n = 5 per group). A novel, ultrasensitive mass spectrometry (MS) based protein profiling approach, using label-free quantification, was applied. The detected cumulus proteome included 2226 quantifiable proteins and was highly influenced by the maturation condition (479 differentially expressed proteins) as well as maturational competence of the corresponding oocyte (424 differentially expressed proteins). Enrichment analysis showed an overrepresentation of the complement and coagulation cascades (CCC), ECM-receptor interaction and steroid biosynthesis in cumulus of COCs that matured successfully under in vivo conditions. Verification of the origin of CCC proteins was achieved through detection of C3 secretion into the maturation medium, with significantly increasing concentrations from 12 (48.4 ng/ml) to 24 hours (68 ng/ml: p < 0.001). In relation, concentrations in follicular fluid, reflecting the in vivo situation, were >100x higher. In summary, this study identified important pathways that are impaired in IVM cumulus, as well as potential markers of the maturational competence of oocytes.

Estradiol and Progesterone Levels are Related to Redox Status in the Follicular Fluid During in vitro Fertilization

Studies have reported a possible association between the levels of oxidative stress biomarkers in follicular fluid (FF) and infertility treatment outcomes. FF analysis can provide important information about oocyte quality. This study aimed to evaluate the possible correlation between oxidative stress biomarker and intrafollicular hormone levels and clinical and laboratory parameters in women during controlled ovarian stimulation. These women were undergoing in vitro fertilization with intracytoplasmic sperm injection (ICSI).The FF samples were acquired from September 2012 to February 2014 from women undergoing private fertility treatment in Rio de Janeiro, Brazil. A total of 196 women who were undergoing ICSI and had different infertility diagnoses were recruited. The FF from each patient (average patient age of 36.3 ± 4.3 years) was collected following puncture of just one follicle with the largest diameter. After ruling out blood contamination by spectrophotometry, 163 patient samples were utilized in the study. In the FF, the progesterone levels were negatively correlated with (a) hydrogen peroxide scavenging capacity (HPSC) (r = −0.294, P < 0.0001), (b) total number of follicles (r = −0.246, P < 0.001) and (c) total number of oocytes punctured (r = −0.268, P = 0.0001). The concentration of serum estradiol exhibited a positive correlation with intrafollicular HPSC (r = 0.165, P = 0.037). Our data indicate that the FF levels of estradiol and progesterone are related to the FF redox status, which is closely associated with the number of oocytes obtained during ICSI procedures.

Comparative Analysis of Porcine Follicular Fluid Proteomes of Small and Large Ovarian Follicles

Ovarian follicular fluid is widely used for in vitro oocyte maturation, but its in-depth characterization to extract full beneficial effects remains unclear. Here, we performed both shotgun (nanoscale liquid chromatography coupled to tandem mass spectrometry or nanoLC-MS/MS) and gel-based (two dimension-differential in-gel electrophoresis or 2D-DIGE) proteomics, followed by functional bioinformatics to compare the proteomes of follicular fluids collected from small (<4 mm) and large (>6-12 mm) follicles of pig ovaries. A total of 2321 unique spots were detected with the 2D-DIGE across small and large follicles, while 2876 proteins with 88% successful annotations were detected with the shotgun approach. The shotgun and 2D-DIGE approaches revealed about 426 and 300 proteins that were respectively common across samples. Six proteins detected with both technical approaches were significantly differently expressed between small and large follicles. Pathways such as estrogen and PI3K-Akt signaling were significantly enriched in small follicles while the complement and coagulation cascades pathways were significantly represented in large follicles. Up-regulated proteins in small follicles were in favor of oocyte maturation, while those in large follicles were involved in the ovulatory process preparation. Few proteins with potential roles during sperm-oocyte interactions were especially detected in FF of large follicles and supporting the potential role of the ovarian FF on the intrafallopian sperm migration and interaction with the oocyte.

Can the Presence of Ovarian Corpus Luteum Modify the Hormonal Composition of Follicular Fluid in Mares?

The hypothesis of this study was to investigate if the presence of corpus luteum (CL) in one ovary could modify the hormonal content of follicular fluid (FF) in the follicles. Sixty ovaries were taken after the slaughter of 30 clinically healthy mares. In relation to the sizes, the follicles were classified into three different categories, as small (20-30 mm), medium (31-40 mm) and large (≥41 mm). Blood samples were collected from the jugular vein of mares before their slaughter, and then the FF samplings were extracted from each single follicle. The ovaries that were collected were classified into two groups, according to the presence (CL-bearing) or absence (non-CL-bearing) of CL. The serum and FF samples were analysed for progesterone (P4), oestradiol-17β (E2), testosterone (T), androstenedione (A4) and dehydroepiandrosterone (DHEA). Intrafollicular P4 concentrations in large follicles of CL-bearing groups were lower than for non-CL-bearing ones. Intrafollicular E2 concentrations increased with the increase of the follicle diameter in both groups, CL-bearing and non-CL-bearing. However, in the FF with a large and medium follicle size, E2 concentrations were significantly higher in non-CL-bearing groups than in CL-bearing groups. T and A4 significantly increased in the large and medium follicle sizes when compared to the small follicle sizes in both groups, but higher concentrations in the non-CL-bearing group were obtained. Intrafollicular DHEA significantly decreased with the increase of the follicular diameter in both groups. Steroid hormones in FF dynamically changed, according to the presence or not of CL in the ovary. This study brings new knowledge on the role of the CL in the follicular hormonal composition in mares.

Proteome changes of porcine follicular fluid during follicle development

Background

Ovarian follicular fluid influences follicle and oocyte growth, but the fluctuation of its protein content during folliculogenesis has not been comprehensively analyzed. Here we used a shotgun approach and bioinformatics analyses to investigate and compare the proteomes of porcine follicular fluid (pFF) obtained from small (< 4 mm), medium (4–6 mm) and large (> 6–12 mm) follicles.

Results

Follicular fluid samples containing highest estrogen levels were selected as non-atretic from small (SNA: 26.1 ± 15 ng/mL), medium (MNA: 162 ± 54 ng/mL), and large (LNA: 290 ± 37 ng/mL) follicles for proteomic analyses. We detected 1627, 1699, and 1756 proteins in SNA, MNA, and LNA samples, respectively. Nearly 60–63% of total proteins were specific to each sample, 11–13% were shared in pairwise comparisons, and 247 proteins were shared among all samples. Functional categorization indicated comparable gene ontology (GO) terms distribution per cellular component, molecular function, and biological process categories across samples; however, the ranking of highly significantly enriched GO terms per category revealed differences between samples. The patterns of protein-to-protein interactions varied throughout follicle development, and proteins such as serine protease inhibitor, clade E (SERPINE); plasminogen activator, urokinase (PLAU); and plasminogen activator, urokinase receptor (PLAUR) appeared stage-specific to SNA, MNA, and LNA, respectively. The “complement and coagulation cascades” was the common major pathway. Besides, properdin and fibulin-1 were abundant proteins that appeared absent in LNA samples.

Conclusion

This study provides extensive and functional analyses of the pFF proteome changes during folliculogenesis and offers the potential for novel biomarker discovery in pFF for oocyte quality assessment.

Protein profile of the ovarian follicular fluid of brown brocket deer (Mazama gouazoubira; Fisher, 1814)

The aim of this study was to characterize the protein profile of ovarian follicular fluid (FF) of brown brocket deer (Mazama gouazoubira). Five adult females received an ovarian stimulation treatment and the FF was collected by laparoscopy from small/medium (≤3.5 mm) and large (>3.5 mm) follicles. Concentrations of soluble proteins in FF samples were measured and proteins were analyzed by 1-D SDS-PAGE followed by tryptic digestion and tandem mass spectrometry. Data from protein list defined after a Mascot database search were analyzed using the STRAP software tool. For the protein concentration, no significant difference (P > 0.05) was observed between small/medium and large follicles: 49.2 ± 22.8 and 56.7 ± 27.4 μg/μl, respectively. Mass spectrometry analysis identified 13 major proteins, but with no significant difference (P > 0.05) between follicle size class. This study provides insight into elucidating folliculogenesis in brown brocket deer.

Intrafollicular and systemic serotonin, oestradiol and progesterone concentrations in cycling mares

The hypothesis that a local serotonergic network might also exist in the follicle of mares remains poorly documented, with exception for humans and laboratory species. For this reason, the aim of the present study was to clarify this possibility, investigating intrafollicular serotonin concentrations of the cycling mare at ovulation time. Sixty ovaries collected from 30 clinically healthy mares of slaughterhouse meat production with clinically normal reproductive tracts after slaughtering were evaluated. Blood samples were taken prior to sacrifice. Follicles were classified in three categories in relation to size, as small (20-30 mm), medium (31-40 mm) and large (>41 mm), and the follicular fluid samples were extracted from each follicle. Intrafollicular and systemic serotonin (5-HT), oestradiol-17β (E₂ ) and progesterone (P₄ ) were determined by means of enzyme-linked immunosorbent assay and RIA, respectively. Intrafollicular 5-HT, E₂ and P₄ concentrations were higher than systemic ones (p < .05). 5-HT concentrations increased in larger compared to medium follicles, without differences compared to small size follicles (p < .05). 5-HT and E₂ (r = .79) and 5-HT and P₄ (r = .79; p < .05) were positively correlated. 5-HT and P₄ concentrations in follicular fluid increased progressively with the increase in follicular size (p < .05). Follicle diameter and E₂ (r = .85) and P₄ (r = .68) were correlated (p < .05). Since serotonin interacts with steroids, its role on steroidogenesis during growth of the dominant follicle may be suggested.

Analysis of the equine "cumulome" reveals major metabolic aberrations after maturation in vitro

Background

Maturation of oocytes under in vitro conditions (IVM) results in impaired developmental competence compared to oocytes matured in vivo. As oocytes are closely coupled to their cumulus complex, elucidating aberrations in cumulus metabolism in vitro is important to bridge the gap towards more physiological maturation conditions. The aim of this study was to analyze the equine “cumulome” in a novel combination of proteomic (nano-HPLC MS/MS) and metabolomic (UPLC-nanoESI-MS) profiling of single cumulus complexes of metaphase II oocytes matured either in vivo (n = 8) or in vitro (n = 7).

Results

A total of 1811 quantifiable proteins and 906 metabolic compounds were identified. The proteome contained 216 differentially expressed proteins (p ≤ 0.05; FC ≥ 2; 95 decreased and 121 increased in vitro), and the metabolome contained 108 metabolites with significantly different abundance (p ≤ 0.05; FC ≥ 2; 24 decreased and 84 increased in vitro). The in vitro “cumulome” was summarized in the following 10 metabolic groups (containing 78 proteins and 21 metabolites): (1) oxygen supply, (2) glucose metabolism, (3) fatty acid metabolism, (4) oxidative phosphorylation, (5) amino acid metabolism, (6) purine and pyrimidine metabolism, (7) steroid metabolism, (8) extracellular matrix, (9) complement cascade and (10) coagulation cascade. The KEGG pathway “complement and coagulation cascades” (ID4610; n = 21) was significantly overrepresented after in vitro maturation. The findings indicate that the in vitro condition especially affects central metabolism and extracellular matrix composition. Important candidates for the metabolic group oxygen supply were underrepresented after maturation in vitro. Additionally, a shift towards glycolysis was detected in glucose metabolism. Therefore, under in vitro conditions, cumulus cells seem to preferentially consume excess available glucose to meet their energy requirements. Proteins involved in biosynthetic processes for fatty acids, cholesterol, amino acids, and purines exhibited higher abundances after maturation in vitro.

Conclusion

This study revealed the marked impact of maturation conditions on the “cumulome” of individual cumulus oocyte complexes. Under the studied in vitro milieu, cumulus cells seem to compensate for a lack of important substrates by shifting to aerobic glycolysis. These findings will help to adapt culture media towards more physiological conditions for oocyte maturation.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5836-5) contains supplementary material, which is available to authorized users.

Hematochemical Patterns in Follicular Fluid and Blood Stream in Cycling Mares: A Comparative Note

The aim of this study was to verify the existence of possible cross-talk between biochemical contents of follicular fluid (FF) and systemic concentrations according to the follicular development of the metabolites: glucose (GLU), lactate (LACT), cholesterol (CHOL), triglycerides (TG), total bilirubin (T BIL), blood urea nitrogen (BUN), and creatinine (CREAT); enzymatic activities: gamma-glutamyl transferase (GGT), lactate dehydrogenase (LDH), alkaline phosphatase (ALP), and aspartate aminotransferase (AST); electrolytes: calcium (Ca), phosphorus (P), sodium (Na), chloride (Cl), potassium (K), magnesium (Mg), and iron (Fe); total proteins (TP) and their fractions: albumin (ALB), α1-, α2-, β-, and γ-globulins (GLOB) of FF and blood strain and their correlations with follicular size in cycling mares. Systemic concentrations of GLU, T BIL, BUN, Fe, TP, ALB, α-1, and α-2 and δ-GLOB and of ALP, GGT, and AST activities were higher than in the FF (P < .05); LACT, CHOL, and TG were higher in FF than systemic ones (P < .05). Glucose, CHOL, TG, LACT, and T BIL were higher in large follicles than in medium and small follicles (P < .05); however, BUN, Fe, ALP, and AST were lower in large follicles than in medium or small follicles (P < .05). Alkaline phosphatase, GGT, and AST activities decreased in medium and large follicles compared with small follicles (P < .05). These results suggest that the metabolic, enzymatic, electrolytic, and protein composition of FF of growing follicles could occur according to the bloodstream changes; hence, it is possible to presume that the nutritional environment of oocyte and follicular cells could improve the clinical diagnoses of infertility in the mare.

Cellular and molecular mechanisms of the preovulatory follicle differenciation and ovulation: What do we know in the mare relative to other species

Terminal follicular differentiation and ovulation are essential steps of reproduction. They are induced by the increase in circulating LH, and lead to the expulsion from the ovary of oocytes ready to be fertilized. This review summarizes our current understanding of cellular and molecular pathways that control ovulation using a broad mammalian literature, with a specific focus to the mare, which is unique in some aspects of ovarian function in some cases. Essential steps and key factors are approached. The first part of this review concerns LH, receptors and signaling, addressing the description of the equine gonadotropin and cloning, signaling pathways that are activated following the binding of LH to its receptors, and implication of transcription factors which better known are CCAAT-enhancer-binding proteins (CEBP) and cAMP response element-binding protein (CREB). The second and major part is devoted to the cellular and molecular actors within follicular cells during preovulatory maturation. We relate to 1) molecules involved in vascular permeability and vasoconstriction, 2) involvement of neuropeptides, such as kisspeptin, neurotrophins and neuronal growth factor, neuropeptide Y (NPY), 3) the modification of steroidogenesis, steroids intrafollicular levels and enzymes activity, 4) the local inflammation, with the increase in prostaglandins synthesis, and implication of leukotrienes, cytokines and glucocorticoids, 5) extracellular matrix remodelling with involvement of proteases, antiproteases and inhibitors, as well as relaxin, and finaly 6) the implication of oxytocine, osteopontin, growth factors and reactive oxygen species. The third part describes our current knowledge on molecular aspect of in vivo cumulus-oocyte-complexe maturation, with a specific focus on signaling pathways, paracrine factors, and intracellular regulations that occur in cumulus cells during expansion, and in the oocyte during nuclear and cytoplasmic meiosis resumption. Our aim was to give an overall and comprehensive map of the regulatory mechanisms that intervene within the preovulatory follicle during differentiation and ovulation.

Seasonal variation in equine follicular fluid proteome

BACKGROUND

Proteomic studies of follicular fluid (FF) exist for several species, including the horse; however, the seasonal influence on FF proteome has not been explored in livestock. The application of high-throughput proteomics of FF in horse has the potential to identify seasonal variations of proteins involved in follicle and oocyte growth.

METHODS

This study (i) profiles the proteomes of equine FF collected from dominant growing follicles during the spring anovulatory season (SAN), and spring (SOV), summer (SUM), and fall (FOV) ovulatory seasons; and (ii) identifies season-dependent regulatory networks and associated key proteins.

RESULTS

Regardless of season, a total of 90 proteins were identified in FF, corresponding to 63, 72, 69, and 78 proteins detected in the SAN, SOV, SUM, and FOV seasons, respectively. Fifty-two proteins were common to all seasons, a total of 13 were unique to either season, and 25 were shared between two seasons or more. Protein-to-protein interaction (PPI) analysis indicated the likely critical roles of plasminogen in the SAN season, the prothrombin/plasminogen combination in SUM, and plasminogen/complement C3 in both SOV and FOV seasons. The apolipoprotein A1 appeared crucial in all seasons. The present findings show that FF proteome of SUM differs from other seasons, with FF having high fluidity (low viscosity).

CONCLUSIONS

The balance between the FF contents in prothrombin, plasminogen, and coagulation factor XII proteins favoring FF fluidity may be crucial at the peak of the ovulatory season (SUM) and may explain the reported lower incidence of hemorrhagic anovulatory follicles during the SUM season.

Genome -wide transcriptome profiling in ovaries of small-tail Han sheep during the follicular and luteal phases of the oestrous cycle

Ovarian function, the control of which is predominantly integrated by the hypothalamic-pituitary-ovarian axis, is pivotal for maintaining reproductive efficiency in sheep. To understand the regulatory mechanism of the follicular-luteal phase transition in prolific sheep, the genome-wide expression patterns of microRNAs and genes in ovarian tissue of Small Tail Han sheep were examined during the follicular and luteal phases of the oestrous cycle. Differentially expressed genes (n = 450) were identified and a total of 139 known and 72 novel miRNAs were identified in the two libraries. It is suggested that differential abundance of miR-200a, 200b and 200c may have an important role in the follicular-luteal transition. A miRNA-regulated gene expression network was created for exploring the regulation of the follicular-luteal transition and quantitative real-time PCR verified the reliability of the RNA-seq data.

Presence of growth/differentiation factor-15 cytokine in human follicular fluid, granulosa cells, and oocytes

PURPOSE

The purpose of the study was to determine whether the GDF-15 is present in follicular fluid; to evaluate if there is a relation between follicular and serum levels of GDF-15 and fertility status of study subjects; and to test whether granulosa cells, oocytes, or both produce GDF-15.

METHODS

This study used follicular fluid (FF, serum, and oocytes obtained under informed consent from women undergoing oocyte retrieval for in vitro fertilization. It also used ovaries from deceased preterm newborns. Collection of FF and blood at the time of oocyte retrieval, ELISA and western blot were performed to determine levels and forms of GDF-15. Concentrations of GDF-15 in FF and serum, its expression in ovarian tissue, and secretion from granulosa cells were analyzed.

RESULTS

GDF-15 concentration in FF ranged from 35 to 572 ng/ml, as determined by ELISA. Western blot analysis revealed the GDF-15 pro-dimer only in FF. Both normal healthy and cancerous granulosa cells secreted GDF-15 into culture media. Primary oocytes displayed cytoplasmic GDF-15 positivity in immunostained newborn ovaries, and its expression was also observed in fully grown human oocytes.

CONCLUSIONS

To the best of our knowledge, this is the first documentation of cytokine GDF-15 presence in follicular fluid. Its concentration was not associated with donor/patient fertility status. Our data also show that GDF-15 is expressed and inducible in both normal healthy and cancerous granulosa cells, as well as in oocytes.

Proteomic analysis of follicular fluid in carriers and non-carriers of the Trio allele for high ovulation rate in cattle

This study was conducted to characterise differences in follicular fluid proteins between carriers and non-carriers of a bovine allele for high ovulation rate. A total of four non-carrier and five carrier females were used in an initial study with four and six additional non-carriers and carriers respectively used in a validation study. Emergence of the follicular wave was synchronised and the ovaries containing the dominant follicle(s) were extracted by ovariectomy for follicular fluid collection. A hexapeptide ligand library was used to overcome the masking effect of high-abundance proteins and to increase detection of low-abundance proteins in tandem mass spectrometry. After correcting for multiple comparisons, only two proteins, glia-derived nexin precursor (SERPINE2) and inhibin β B chain precursor (INHBB), were significantly differentially expressed (false-discovery rate <0.05). In a replicate study of analogous design differential expression was confirmed (P < 0.05). Joint analysis of results from the two studies indicated that three additional proteins were consistently differentially expressed between genotypes. For three of these five, previous studies have indicated that expression is increased by transforming growth factor-β–bone morphogenetic protein signalling; their reduction in follicular fluid from carrier animals is consistent with the ~9-fold overexpression of SMAD family member 6 (SMAD6) in carriers that is inhibitory to this pathway.

Applying a systems approach to thyroid physiology: Looking at the whole with a mitochondrial perspective instead of judging single TSH values or why we should know more about mitochondria to understand metabolism

Classical thinking in endocrine physiology squeezes our diagnostic handling into a simple negative feedback mechanism with a controller and a controlled variable. In the case of the thyroid this is reduced to TSH and fT3 and fT4, respectively. The setting of this tight notion has no free space for any additions. In this paper we want to challenge this model of limited application by proposing a construct based on a systems approach departing from two basic considerations. In first place since the majority of cases of thyroid disease develop and appear during life it has to be considered as an acquired condition. In the second place, our experience with the reversibility of morphological changes makes the autoimmune theory inconsistent.

While medical complexity can expand into the era of OMICS as well as into one where manipulations with the use of knock-outs and -ins are common in science, we have preferred to maintain a simple and practical approach. We will describe the interactions of iron, magnesium, zinc, selenium and coenzyme Q10 with the thyroid axis. The discourse will be then brought into the context of ovarian function, i.e. steroid hormone production. Finally the same elemental players will be presented in relation to the basic mitochondrial machinery that supports the endocrine.

We propose that an intact mitochondrial function can guard the normal endocrine function of both the thyroid as well as of the ovarian axis. The basic elements required for this function appear to be magnesium and iron. In the case of the thyroid, magnesium-ATP acts in iodine uptake and the heme protein peroxidase in thyroid hormone synthesis. A similar biochemical process is found in steroid synthesis with cholesterol uptake being the initial energy-dependent step and later the heme protein ferredoxin 1 which is required for steroid synthesis. Magnesium plays a central role in determining the clinical picture associated with thyroid disease and is also involved in maintaining fertility. With the aid of 3D sonography patients needing selenium and/or coenzyme Q10 can be easily identified. By this we firmly believe that physicians should know more about basic biochemistry and the way it fits into mitochondrial function in order to understand metabolism. Contemplating only TSH is highly reductionistic.

Outline

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Author's profiles and motivation for this analysis

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The philosophical alternatives in science and medicine

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Reductionism vs. systems approach in clinical thyroid disease guidelines

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The entry into complexity: the involvement of the musculoskeletal system

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Integrating East and West: teachings from Chinese Medicine and from evidence based medicine (EBM)

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Can a mathematical model represent complexity in the daily thyroid practice?

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How effective is thyroxine treatment?

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Resolving the situation of residual symptoms in treated patients with thyroid disease

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Importance of iron, zinc and magnesium in relation to thyroid function

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Putting together new concepts related to thyroid function for a systems approach

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Expanding our model into general aspects of medicine

Shotgun proteomics of rainbow trout ovarian fluid

In the present study we used a shotgun proteomic approach to identify 54 proteins of rainbow trout ovarian fluid. The study has unravelled the identity of several proteins not previously reported in fish ovarian fluid. The proteome of trout ovarian fluid consists of diverse proteins participating in lipid binding and metabolism, carbohydrate and ion transport, innate immunity, maturation and ovulation processes. Most trout ovarian fluid proteins correspond to follicular fluid proteins of higher vertebrates, but 15% of the proteins were found to be different, such as those related to the immune system (precerebellin-like protein), proteolysis (myeloid cell lineage chitinase), carbohydrate and lipid binding and metabolism (vitellogenins), cell structure and shape (vitelline envelope protein gamma) and a protein with unknown functions (UPF0762 protein C6orf58 homologue). The present study could help in the decoding of the biological function of these proteins and in the discovery of potential biomarkers of oocyte quality.

Protocol for Exosome Isolation from Small Volume of Ovarian Follicular Fluid: Evaluation of Ultracentrifugation and Commercial Kits

The ovarian follicular fluid (FF) is a complex fluid that constitutes the microenvironment of developing follicles and contains factors secreted by the surrounding cells and blood plasma compounds that cross the "blood-follicle barrier." Upon oocyte retrieval (in human, bovine, and equine) the follicular fluid is normally discarded and represents a repertoire of cellular messages exchanged during follicle development, thus providing a suitable sample for performing oocyte quality diagnostics. Several studies report on the presence of extracellular vesicles (EVs) in FF from human, bovine and equine. Here, we describe the process of FF collection from human and bovine and the enrichment and isolation of EVs that we termed folliculosomes (FFEs), using available commercial kits as well as the traditional ultracentrifugation methods.

Influence of Estradiol-17beta on Progesterone and Estrogen Receptor mRNA Expression in Porcine Follicular Granulosa Cells during Short-Term, In Vitro Real-Time Cell Proliferation

Progesterone (P4) and estradiol (E2) play a significant role in mammalian reproduction. Our study demonstrated that separated porcine cumulus cells (CCs) and/or granulosa cells (GCs) might proliferate in vitro during short-term, real-time primary culture. The GCs were analyzed according to gene expression of the progesterone receptor (nuclear form) (pgr), progesterone receptor membrane component 1 (pgrmc1), and estrogen-related receptor beta 3 (esrrb3) in relation to two housekeeping genes: actb and pbgd. GCs were cultivated in medium with the E2. Both pgr/actb and pgr/pbgd revealed higher expression between 24 and 168 h of IVC of prolonged E2 treatment and at 48 h of IVC after acute E2 administration. The pgrmc1/actb and pgrmc1/pbgd displayed increased expression after prolonged E2 treatment between 24 and 120 h of IVC. The highest level of esrrb3/actb at 120 and 144 h, as well as esrrb3/pbgd at 120 h, in untreated controls as compared to the hormone-stimulated group, was observed. We suggest that E2 significantly influences the upregulation of pgr, pgrmc1, and esrrb3 expression in porcine GCs during real-time cell proliferation. Since esrrb3 expression is stimulated by E2 in both an acute and prolonged manner, estradiol may be recognized as a potential estrogen receptor agonist in GCs.

Proteome Profile and Quantitative Proteomic Analysis of Buffalo (Bubalusbubalis) Follicular Fluid during Follicle Development

Follicular fluid (FF) accumulates in the antrum of the ovarian follicle and provides the microenvironment for oocyte development. FF plays an important role in follicle growth and oocyte maturation. The FF provides a unique window to investigate the processes occurring during buffalo follicular development. The observed low quality of buffalo oocytes may arise from the poor follicular microenvironment. Investigating proteins found in buffalo FF (BFF) should provide insight into follicular development processes and provide further understanding of intra-follicular maturation and oocytes quality. Here, a proteomic-based approach was used to analyze the proteome of BFF. SDS-PAGE separation combined with mass spectrometry was used to generate the proteomic dataset. In total, 363 proteins were identified and classified by Gene Ontology terms. The proteins were assigned to 153 pathways, including signaling pathways. To evaluate difference in proteins expressed between BFF with different follicle size (small, <4 mm; and large, >8 mm), a quantitative proteomic analysis based on multi-dimensional liquid chromatography pre-fractionation tandem Orbitrap mass spectrometry identification was performed. Eleven differentially expressed proteins (six downregulated and five upregulated in large BFF) were identified and assigned to a variety of functional processes, including serine protease inhibition, oxidation protection and the complement cascade system. Three differentially expressed proteins, Vimentin, Peroxiredoxin-1 and SERPIND1, were verified by Western blotting, consistent with the quantitative proteomics results. Our datasets offers new information about proteins present in BFF and should facilitate the development of new biomarkers. These differentially expressed proteins illuminate the size-dependent protein changes in follicle microenvironment.

Proteomic analysis of the follicular fluid of Tianzhu white yak during diestrus

The aim of this study was to identify differentially expressed proteins in the follicular fluid of Tianzhu white yak during diestrus. Follicles obtained from female yak were divided into four groups according to their diameter: 0–2, 2–4, 4–6 mm, and greater than 6 mm. The follicular fluid was directly aspirated from the follicles and mixed according to follicular size, and two-dimensional gel electrophoresis was carried out on the crude follicular fluid samples. Thirty-four differentially expressed spots were generated from these four sizes of follicles. Fourteen of these spots were analyzed by MALDI-TOF/TOF-MS and identified as: AS3MT, VDP, ANKRD6, C10orf107 protein, MRP4, MAPKAP1, AGO3, profilin-β-actin, SPT2 homolog, AGP, AR, RNF20, obscurin-like-1, and one unnamed protein. These proteins were first reported in follicular fluid, in addition to VDP and AGP. Based on existing knowledge of their function and patterns of expression, we hypothesize that most of these differentially expressed proteins play a role in ovarian follicular growth and development, dominant follicle selection, or follicular atresia and development of oocytes; however, the function of the other differentially expressed proteins in reproduction remains ambiguous.