Relationship between low-molecular-weight insulin-like growth factor-binding proteins, caspase-3 activity, and oocyte quality

Effect of IGFBP-4 during In Vitro Maturation on Developmental Competence of Bovine Cumulus Oocyte Complexes

Insulin-like growth factors (IGFs) are essential for oocyte maturation. Their bioavailability is regulated by their respective binding proteins (IGFBPs) and proteases. IGFBP-4 blocks the biological effects of IGFs. High IGFBP-4 expression has been associated with follicle atresia. We hypothesized that IGFBP-4 affects oocyte developmental competence during maturation. Therefore, the aim of this study was to examine the effect of IGFBP-4 on the developmental rate of bovine cumulus-oocyte complexes (COCs) during in vitro embryo production. Abattoir-derived COCs were matured with rbIGFBP-4 (2000, 540, and 54 ng/mL) compared to a control. Cumulus expansion, oocyte maturation, cleavage, blastocyst, and hatching rates were evaluated. Furthermore, blastocyst gene expression of SOCS2, STAT3, SLC2A1, SLCA3, BAX, and POU5F1 transcripts were quantified using RT-qPCR. No statistical differences were detected among the groups for cumulus expansion, maturation, cleavage, blastocyst rates, or all gene transcripts analyzed. However, at day 8 and 9, the number of total hatching and successfully hatched blastocysts was lower in 2000 ng/mL rbIGFBP-4 compared to the control (day 8: total hatching: 17.1 ± 0.21 vs. 31.2 ± 0.11%, p = 0.02 and hatched blastocyst 6.7 ± 0.31 vs. 21.5 ± 0.14%, p = 0.004; day 9 total hatching 36.4 ± 0.18 vs. 57.7 ± 0.10%, p = 0.009 and hatched blastocyst 18.2 ± 0.21 vs. 38.1 ± 0.11%, p = 0.004). We concluded that high concentrations of rbIGFBP-4 might negatively affect the subsequent ability of the embryo to hatch and possibly compromise further elongation.

Protective effect of onion peel extract on ageing mouse oocytes

Mammalian oocytes not fertilized immediately after ovulation can undergo ageing and a rapid decline in quality. The addition of antioxidants can be an efficient approach to delaying the oocyte ageing process. Onion peel extract (OPE) contains quercetin and other flavonoids with natural antioxidant activities. In this study, we investigated the effect of OPE on mouse oocyte ageing and its mechanism of action. The oocytes were aged in vitro in M16 medium for 16 h after adding OPE at different concentrations (0, 50, 100, 200, and 500 μg/ml). The addition of 100 μg/ml OPE reduced the oocyte fragmentation rate, decreased the reactive oxygen species (ROS) level, increased the glutathione (GSH) level, and improved the mitochondrial membrane potential compared with the control group. The addition of OPE also increased the expression of SOD1, CAT, and GPX3 genes, and the caspase-3 activity in OPE-treated aged oocytes was significantly lower than that in untreated aged oocytes and similar to that in fresh oocytes. These results indicated that OPE delayed mouse oocyte ageing by reducing oxidative stress and apoptosis and enhancing mitochondrial function.

Quercetin protects mouse oocytes against chromium-induced damage in vitro and in vivo

BACKGROUND

Chromium (Cr) is a naturally-occurring element that is used in various fields of industry. Humans may be exposed to hexavalent chromium [Cr(VI)], which is one of the stable valence states of the chromium through contaminated soil, air, and water. Exposure to Cr(VI) through contaminated drinking water, soil and air causes various cancers and also fertility problems in animals and humans. Quercetin (QCT), a common flavonoid compound, has numerous biological effects as an antioxidant and free radical scavenger, but its function and mechanisms in reproductive processes in various species remain unclear. This study aims to determine the chromium effects on mice oocyte quality and the ameliorative effect of QCT in both in vitro and in vivo experimental models.

METHODS

For the in vitro experiment, oocytes were collected and divided into the control, sham, QCT-treated, Cr(VI) (potassium dichromate), and treatment [Cr(VI)+QCT] groups. Collected oocytes were cultured in maturation medium with or without 10 µM quercetin and 10 µM Cr(VI) for 14 h based on the defined experimental design. For the in vivo experiment, the mice were randomly divided into the control, sham, QCT-treated, Cr(VI), and Cr(VI) + QCT groups. Control and sham mice received regular drinking water and diet. Cr(VI) group received Cr(VI) (50 ppm in drinking water) and Cr(VI) + QCT group received 50 ppm Cr(VI) with QCT (20 mg/kg body wt, through i.p) for a period of 21 days and then oocytes were collected and cultured for 14 h for in vitro maturation. For both experiments, at the end of the culture period, we examined the ameliorative effect of QCT on oocyte maturation, spindle formation, ROS production, mitochondrial function, and apoptosis.

RESULTS

Our in vitro and in vivo results showed that Cr(VI) disrupt the oocyte maturation and spindle formation (P < 0.001). Furthermore, we found that exposure to Cr(VI) significantly increased ROS levels and decreased mitochondrial membrane potential (P < 0.001). In addition, exposure to Cr(VI) induced early apoptosis and downregulated the Bcl-2 mRNA expression and upregulated the Caspase-3 and Bax mRNAs expression (P < 0.01). Finally, quercetin significantly restored the detrimental effects of Cr(VI).

CONCLUSION

The results indicated that quercetin protects the oocytes against Cr(VI) toxicity through the suppression of oxidative stress and apoptosis. The conclusions drawn from our study's findings suggest that quercetin might be useful agent for oocyte maturation in case of possible exposure to toxic substances such as chromium.

Effect of Nellore (Bos indicus) donor age on in vitro embryo production and pregnancy rate

The aim of this study was to evaluate the effect of age of Nellore (Bos indicus) donors on the efficiency of in vitro embryo production (IVEP) and pregnancy rate. Thirty-six donors, including 11 female calves (13±0.61 months), 17 prepubertal heifers (25±0.78 months) and 8 cows (83±28 months), were submitted to 3 procedures of ovum pick up (OPU) on random days of the estrous cycle at intervals of 21 days. Caspase-3 and IGFBP2 were quantified in oocytes and blastocysts for the evaluation of oocyte and embryo quality. The produced embryos were vitrified (n=445) and transferred to synchronized recipients. Cows produced a larger number of follicles (cows: 54.5±6.2; calves: 20.0±0.57; prepubertal heifers: 20.8±0.46), total oocytes (cows: 45.97±7.22; calves: 28.93±6.14; prepubertal heifers: 27.21±4.94), and cleaved oocytes (cows: 21.14±4.22; calves: 13.09±3.72; prepubertal heifers: 12.4±3.19). The cleavage rate was similar between age categories; however, cows tended (p<0.07) to produce a larger number of blastocysts (9.74±2.26) per OPU than calves (5.57±1.99) and prepubertal heifers tended to have a higher blastocyst yield (35.4%) than calves (27.1%) (p<0.07). The expression levels of IGFBP2 and caspase-3 were higher in oocytes derived from calves compared to the other two categories. The pregnancy rate was higher in calves (43.1%) and cows (40.4%) than in prepubertal heifers (33.8%) (p=0.03). Despite the larger numbers of follicles and viable oocytes in cows, the blastocyst production results and pregnancy rates obtained indicate that the use of young females as oocyte donors in IVEP is feasible and may contribute to reduce the generation interval.

Toxic effects of methomyl on mouse oocytes and its possible mechanisms

Methomyl is a broad-spectrum carbamate insecticide that has a variety of toxic effects on humans and animals. However, there have been no studies on the toxicity of methomyl in female mammalian oocytes. This study investigated the toxic effects of environmental oestrogen methomyl exposure on mouse oocyte maturation and its possible mechanisms. Our results indicated that methomyl exposure inhibited polar body extrusion in mouse oocytes. Compared with that in the control group, in the methomyl treatment group, superoxide anion free radicals in oocytes were significantly increased. In addition, the mitochondrial membrane potential of metaphase II stage oocytes in the methomyl treatment group was significantly decreased, resulting in reduced mouse oocyte quality. After 8.5 h of exposure to methomyl, metaphase I stage mouse oocytes displayed an abnormal spindle morphology. mRNA expression of the pro-apoptotic genes Bax and Caspase-3 in methomyl-treated oocytes increased, which confirmed the apoptosis. Collectively, our results indicated that mouse oocyte maturation is defective after methomyl treatment at least through disruption of spindle morphology, mitochondrial function and by induction of oxidative stress.

Downregulating lncRNA NEAT1 induces proliferation and represses apoptosis of ovarian granulosa cells in polycystic ovary syndrome via microRNA-381/IGF1 axis

OBJECTIVE

Researchers have revealed the combined functions of long noncoding RNAs (lncRNAs) and microRNA (miRNAs) in polycystic ovary syndrome (PCOS). This study aimed to understand the role of nuclear-enriched abundant transcript 1 (NEAT1) and miR-381 involving insulin-like growth factor 1 (IGF1) in PCOS.

METHODS

PCOS rat model was established by dehydroepiandrosterone induction. NEAT1, miR-381 and IGF1 expression in ovarian granulosa cells of PCOS patients and ovarian tissues of PCOS rats were tested. Bioinformatics website and dual luciferase reporter gene assay were utilized to verify the relationship between NEAT1 and miR-381 and that between miR-381 and IGF1. Levels of sex hormone, pathological changes and ovarian granulosa cell apoptosis in ovarian tissues of PCOS rats were detected. Ovarian granulosa cell proliferation and apoptosis were analyzed in vitro.

RESULTS

NEAT1 and IGF1 expression increased while miR-381 expression decreased in the ovarian granulosa cells of patients with PCOS and the ovarian tissues of PCOS rats. In in vivo experiments, interference with NEAT1 improved the levels of sex hormones, alleviated pathological changes and suppressed ovarian granulosa cell apoptosis in the ovarian tissues of PCOS rats. In in vitro cell experiments, interference with NEAT1 suppressed apoptosis and enhanced cell proliferation of ovarian granulosa cells. NEAT1 interference-mediated effect would be reversed by up-regulating miR-381. NEAT1 acted as a ceRNA to adsorb miR-381 to target IGF1. Overexpression of IGF1 reversed the inhibitory effect of miR-381 on ovarian granulosa cell apoptosis.

CONCLUSION

Interference with NEAT1 increases miR-381 and reduces IGF1 levels, effectively improving the levels of sex hormones and reducing the pathological damage of ovarian tissue in rats with PCOS.

L-carnitine prevents bovine oocyte aging and promotes subsequent embryonic development

L-carnitine (LC) is well known for its antioxidant activity. In this study, we explored the potential mechanistic effects of LC supplementation on aged bovine oocytes in vitro. We showed that in-vitro maturation could enhance the subsequent developmental capacity of aging oocytes, when supplemented with LC. After in vitro fertilization, the blastocyst formation rate in the aged oocytes post-LC treatment significantly increased compared to that in untreated aged oocytes (29.23 ± 2.20% vs. 20.90 ± 3.05%). Furthermore, after LC treatment, the level of intracellular reactive oxygen species in aged oocytes significantly decreased, and glutathione levels significantly increased, compared to those in untreated aged oocytes. Mitochondrial membrane potential, the percentage of early apoptotic oocytes, and caspase-3 activity were significantly reduced in LC-treated aged oocytes compared to those in untreated aged oocytes. Furthermore, during in vitro aging, the mRNA levels of the anti-apoptotic genes, Bcl-xl and survivin in LC-treated aged oocytes were significantly higher than those in untreated aged oocytes. Overall, these results indicate that at least in in vitro conditions, LC can prevent the aging of bovine oocytes and improve the developmental capacity of bovine embryo.

Potential Functions of IGFBP-2 for Ovarian Folliculogenesis and Steroidogenesis

Ovarian follicles, as transient structural and functional complexes with the oocyte and the associated cells, determine the female reproductive cycle and thus fertility. Ovarian function is subject to the strict control of hormones and growth factors and thus regulated by auto-, para-, and endocrine mechanisms but influenced also by endogenous factors. During the waves of follicular growth and development, one follicle (monoovulatory) or a limited number of them (polyovulatory) are selected under hypothalamic-gonadal control for maturation until ovulation, resulting in the fertile oocyte. Subordinate follicles inevitably enter different stages of atresia. A number of studies have observed species-specific alterations of IGFBP-2 levels during the phases of growth and development or selection and atresia of follicles. IGFBP-2 is thus probably involved in the process of follicle growth, differentiation, and degeneration. This may occur on the levels of IGF-dependent and -independent growth control but also due to the control of steroidogenesis, e.g., via induction of aromatase expression. In mice, IGFBP-2 delayed reproductive development most probably by IGF-independent mechanisms. Because reproductive development is closely linked to the control of life- or health-span and energy metabolism, we feel that the time is right now to resume research on the effects of IGFBP-2 in the ovarian follicular compartment.

Identification and expression of X-linked inhibitor of apoptosis protein during follicular development in goat ovary

X-linked inhibitor of apoptosis protein (XIAP), an endogenous of inhibitor of caspases, plays crucial roles in regulating ovarian granulosa cell apoptosis during follicular atresia. The aim of the present study was to determine the presence and localization of XIAP in the goat ovary and its expression level during follicular development. The full length cDNA of XIAP from goat ovary cells was cloned using reverse transcription PCR. A total of 497 amino acid residues were encoded by open reading frame and had high identity with homologous sequences from other mammals. XIAP was widely expressed in adult goat tissues as determined by real-time PCR and it demonstrated higher expression in propagative organs. High level of XIAP was detected in large healthy follicles and corpus luteum in comparison with that in small antral follicles, which was in accordance with the immunohistochemistry results and atretic follicles had very low expression. XIAP was localized in both granulosa and theca cells in antral follicles but not in primordial follicles. Furthermore, luteinizing hormone stimulated the proliferation of mRNA encoding XIAP in granulosa cells in vitro. The present study demonstrated that XIAP was expressed in a follicular-stage-dependent manner in goat ovaries.

Intact cell MALDI-TOF mass spectrometry on single bovine oocyte and follicular cells combined with top-down proteomics: A novel approach to characterise markers of oocyte maturation

Intact cell MALDI-TOF mass spectrometry (ICM-MS) was adapted to bovine follicular cells from individual ovarian follicles to obtain the protein/peptide signatures (<17kDa) of single oocytes, cumulus cells (CC) and granulosa cells (GC), which shared a total of 439 peaks. By comparing the ICM-MS profiles of single oocytes and CC before and after in vitro maturation (IVM), 71 different peaks were characterised, and their relative abundance was found to vary depending on the stage of oocyte meiotic maturation. To identify these endogenous biomolecules, top-down workflow using high resolution MS/MS (TD HR-MS) was performed on the protein extracts from oocytes, CC and GC. The TD HR-MS proteomic approach allowed for: (1) identification of 386 peptide/proteoforms encoded by 194 genes; and (2) characterisation of proteolysis products likely resulting from the action of kallikreins and caspases. In total, 136 peaks observed by ICM-MS were annotated by TD HR-MS (ProteomeXchange PXD004892). Among these, 16 markers of maturation were identified, including IGF2 binding protein 3 and hemoglobin B in the oocyte, thymosins beta-4 and beta-10, histone H2B and ubiquitin in CC. The combination of ICM-MS and TD HR-MS proved to be a suitable strategy to identify non-invasive markers of oocyte quality using limited biological samples.

BIOLOGICAL SIGNIFICANCE

Intact cell MALDI-TOF mass spectrometry on single oocytes and their surrounding cumulus cells, coupled to an optimised top-down HR-MS proteomic approach on ovarian follicular cells, was used to identify specific markers of oocyte meiotic maturation represented by whole low molecular weight proteins or products of degradation by specific proteases.

Interplay between autophagy and apoptosis in the development of Danio rerio follicles and the effects of a probiotic

The present study investigated autophagic processes in Danio rerio preovulatory follicles (Stage III and IV). There were more autophagosomes, as revealed by electron microscopy, in follicles from females fed the probiotic Lactobacillus rhamnosus IMC 501. This was confirmed by increased expression of genes involved in the autophagic process, namely ambra1, becn1, lc3 and uvrag. In addition, preovulatory follicles from females fed the probiotic contained more microtubule-associated protein 1 light chain 3 isoform II (LC3-II) and less p62 protein. The increased autophagy in preovulatory follicles from females fed the probiotic was concomitant with a decrease in the apoptotic process in the ovary, as evidenced by terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labelling analysis and confirmed by lower expression of genes involved in apoptosis (i.e., p53, bax, apaf and cas3) and higher expression as igfII and igf1r. The results of the present study provide preliminary evidence of the involvement of autophagy during follicle development in the zebrafish ovary. In addition, we have demonstrated for the first time that a functional food, such as L. rhamnosus IMC 501, can modulate the balance between apoptosis and autophagy that regulates ovary physiology in zebrafish by inhibiting follicular apoptosis and improving follicular survival.

Differential gene expression in cumulus oocyte complexes collected by ovum pick up from repeat breeder and normally fertile Holstein Friesian heifers

The aim of this study was to establish whether perturbed gene expression during cumulus oocyte development causes repeat breeding in cattle. In this study, a repeat breeder was defined as a normal estrous cycling animal that did not become pregnant after three inseminations despite the absence of clinically detectable reproductive disorders. Transcripts of genes extracted from cumulus oocyte complexes (COC) that were collected from three repeat breeder and three normally fertile Holstein Friesian heifers were compared. Up to 40 COC were collected from each heifer by means of repeated sessions of ovum pick up in the absence of hormonal stimulation; immediately plunged into liquid nitrogen; and stored at -80°C until analysis. For each heifer, RNA was extracted from the pooled COC and hybridized on GeneChip(®) Bovine Gene Array (Affymetrix). Analysis of gene expression profiles of repeat breeder and control COC showed that 178 genes were differentially expressed (log2 fold change>1.5). Of these genes, 43 (24%) were up-regulated and 135 (76%) were down-regulated in repeat breeder relative to control heifers. This altered pattern of expression occurred in genes involved in several cellular biological processes and cellular components such as metabolism, angiogenesis, substrate/ion transport, regulation/signaling, cell adhesion and cytoskeleton. From these, 13 genes potentially involved in cumulus oocyte growth were subjected to validation by qRT-PCR and nine genes (annexin A1, ANXA1; lactoferrin, LTF; interferon stimulated exonuclease 20kDa, ISG20/HEM45; oxidized low density lipoprotein receptor 1, OLR1; fatty acid desaturase 2, FADS2; glutathione S-transferase A2 and A4, GSTA2 and GSTA4; glutathione peroxidase 1, GPX1; endothelin receptor type A, EDNRA) were confirmed to be differentially expressed. This study identified potential marker genes for fertility in dairy cattle.

Microarray analysis of mRNA from cumulus cells following in vivo or in vitro maturation of mouse cumulus–oocyte complexes

The IVM of mammalian cumulus–oocyte complexes (COCs) yields reduced oocyte developmental competence compared with oocytes matured in vivo. Altered cumulus cell function during IVM is implicated as one cause for this difference. We have conducted a microarray analysis of cumulus cell mRNA following IVM or in vivo maturation (IVV). Mouse COCs were sourced from ovaries of 21-day-old CBAB6F1 mice 46 h after equine chorionic gonadotrophin (5 IU, i.p.) or from oviducts following treatment with 5 IU eCG (61 h) and 5 IU human chorionic gonadotrophin (13 h). IVM was performed in α-Minimal Essential Medium with 50 mIU FSH for 17 h. Three independent RNA samples were assessed using the Affymetrix Gene Chip Mouse Genome 430 2.0 array (Affymetrix, Santa Clara, CA, USA). In total, 1593 genes were differentially expressed, with 811 genes upregulated and 782 genes downregulated in IVM compared with IVV cumulus cells; selected genes were validated by real-time reverse transcription–polymerase chain reaction (RT-PCR). Surprisingly, haemoglobin α (Hba-a1) was highly expressed in IVV relative to IVM cumulus cells, which was verified by both RT-PCR and western blot analysis. Because haemoglobin regulates O2 and/or nitric oxide availability, we postulate that it may contribute to regulation of these gases during the ovulatory period in vivo. These data will provide a useful resource to determine differences in cumulus cell function that are possibly linked to oocyte competence.

Zona pellucida birefringence correlates with developmental capacity of bovine oocytes classified by maturational environment, COC morphology and G6PDH activity

In the present study we aimed to analyse structural changes during in vitro maturation of the bovine zona pellucida (ZP) by scanning electron microscopy (SEM) ands zona pellucida birefringence (ZPB). Here we show that alterations during in vitro maturation invasively analysed by SEM are reflected in ZPB. In vivo-matured oocytes displayed significantly lower birefringence parameters and significantly higher blastocyst rates compared with in vitro-derived oocytes (39.1% vs 21.6%). The same was observed for in vitro-matured oocytes with cumulus-oocyte complex (COC) Quality 1 (Q1) compared with Q3-COCs with respect to zona birefringence and developmental capacity. Immature oocytes with Q1-COCs displayed higher ZPB values and a higher developmental capacity to the blastocyst stage (27.7% vs 16.9%) compared with immature Q3-COCs. Considering in vitro-matured oocytes, only those with Q1-COC showed a trend for ZPB similar to in vivo-matured oocytes. Therefore, a decreasing trend for ZPB during in vitro maturation seems to be typical for high-quality oocytes and successful cytoplasmic maturation. In accordance, fully-grown immature oocytes reached significantly higher blastocyst rates (32.0% vs 11.5%) and lower ZPB values compared with still-growing ones. In conclusion, we successfully evaluated the applicability of zona imaging to bovine oocytes: alterations during in vitro maturation invasively analysed by scanning electron microscopy were reflected in the birefringence of the zona pellucida of bovine oocytes affecting developmental capacity at the same value. Therefore ZPB measurement by live zona imaging has potential to become a new tool to assess correctness of in vitro maturation and to predict developmental competence.

Incidence of apoptosis and transcript abundance in bovine follicular cells is associated with the quality of the enclosed oocyte

The close contact and interaction between the oocyte and the follicular environment influence the establishment of oocyte developmental competence. Moreover, it is assumed that apoptosis in the follicular cells has a beneficial influence on the developmental competence of oocytes. The aim of this study was to investigate whether bovine oocytes with varied developmental competence show differences in the degree of apoptosis and gene expression pattern in their surrounding follicular cells (cumulus and granulosa cells). Oocytes and follicular cells from follicles of 3 to 5 mm in diameter were grouped as brilliant cresyl blue (BCB)+ and BCB- based on glucose-6-phosphate dehydrogenase (G6PDH) activity in the ooplasm by BCB staining. In the follicular cells initial, early and late apoptotic events were assessed by analyzing caspase-3 activity, annexin-V and TUNEL, respectively. Global gene expression was investigated in immature oocytes and corresponding follicular cells. BCB+ oocytes resulted in a higher blastocyst rate (19.3%) compared to the BCB- group (7.4%, P < 0.05). Moreover, the analysis of apoptosis showed a higher caspase-3 activity in the follicular cells and an increased degree of late apoptotic events in granulosa cells in the BCB+ compared with the BCB- group. Additionally, the global gene expression profile revealed a total of 34 and 37 differentially expressed genes between BCB+ and BCB- cumulus cells and granulosa cells, respectively, whereas 207 genes showed an altered transcript abundance between BCB+ and BCB- oocytes. Among these, EIF3F, RARRES2, RNF34, ACTA1, GSTA1, EIF3A, VIM and CS gene transcripts were most highly enriched in the BCB+ oocytes, whereas OLFM1, LINGO1, ALDH1A3, PTHLH, BTN3A3, MRPS2 and PPM1K were most significantly reduced in these cells. Therefore, the follicular cells enclosing developmentally competent oocytes show a higher level of apoptosis and a different pattern of gene expression compared to follicular cells enclosing non-competent bovine oocytes.

X-linked inhibitor of apoptosis protein and active caspase-3 expression patterns in antral follicles in the sheep ovary

X-linked inhibitor of apoptosis protein (XIAP) interacts with caspases to inhibit their activity, thereby providing a potential mechanism for regulation of granulosa cell apoptosis occurring during follicular atresia. The aim of this study was to determine the presence and localization of XIAP mRNA and protein content in the sheep ovary and compare these expression patterns with active caspase-3 protein in the same antral follicles. Romney ewe estrous cycles (n=25) were synchronized with 2–3 Estrumate injections and ovarian tissue collected during the luteal and follicular phases of the cycle. The presence ofXIAPmRNA was confirmed by RT-PCR using laser capture microdissected ovarian cell samples.XIAPmRNA was subsequently localized byin situhybridization histochemistry and XIAP and active caspase-3 protein visualized by immunohistochemistry. In antral follicles extensive XIAP localization was evident in both granulosa and thecal cells. In contrast, mRNA expression was widespread in granulosa cells and only detected in thecal tissue from a small proportion of antral follicles. Active caspase-3 and XIAP comparative expression analysis showed positiveXIAPmRNA expression in all late luteal phase (day 14) follicles, despite varying levels of active caspase-3 protein. A proportion of follicular phase (days 15 and 16) follicles, however, showed an inverse expression relationship at the protein and mRNA levels in both granulosa and thecal tissue, as did XIAP protein in day 14 follicles. These results suggest high XIAP may prevent activation of caspase-3, thereby regulating follicular atresia in antral follicles and could potentially be utilized as a marker of follicular health.

In vitro maturation supplements affect developmental competence of bovine cumulus-oocyte complexes and embryo quality after vitrification

Oocyte quality affects subsequent embryo development and quality. We examined the impact of bovine oocyte in vitro maturation (IVM) conditions on subsequent embryo yield, quality and cryosurvival. Cumulus-oocyte complexes (COCs) were sampled for cytological and gene expression analysis after IVM in TCM199 supplemented with 10% fetal bovine serum (FBS), 4 mg/ml of fatty-acid-free bovine serum albumin (FAFBSA), 4 mg/ml of polyvinylpyrrolidone (PVP), FAFBSA with epidermal growth factor (EGF, 100 ng/ml) and insulin-like growth factor 1 (IGF-I, 100 ng/ml) (FAFBSAGF), PVP with EGF and IGF-I (PVPGF) or PVP with single strength BME and MEM amino acids (PVPAA). The remaining COCs were fertilized. On day 7 (IVF=day 0) quality 1 blastocysts were vitrified or analyzed for glucose transporter 1 (Glut-1) expression levels. The remaining blastocysts (days 7-9) were evaluated for morphology and total cell counts. After warming, survival and hatching rates were evaluated followed by total cell counts and Glut-1 expression levels. Only PVPGF IVM resulted in embryo production rates comparable to those recorded with FBS IVM. Growth factors with FAFBSA and amino acids with PVP reduced embryo production rates whereas the effect of the growth factors with PVP was negligible. Insulin-like growth factor 2 binding protein 3 (IGF2BP3) and beta cell translocation gene 4 (BTG4) were revealed as potential candidates for oocyte developmental competence, and secreted protein, acidic and rich in cysteine (SPARC) for cumulus cell expansion. There were no differences among treatments in hatching rates of vitrified embryos after warming. However, total cell numbers and Glut-1 expression levels at 72 h were affected.

Presence of cleaved caspase 3 in swine embryos of different developmental capacities produced by parthenogenetic activation

This study assessed the presence of cleaved caspase 3 (CC3) during the in vitro development of swine embryos produced by parthenogenetic activation (PA). Embryos with high and low capacity to develop into blastocysts and the exposure to a caspase inhibitor (z-DEVD-fmk) were used to investigate the effect of CC3 on embryo development. The blastocyst rate (64.3% vs. 16.4%) and the average number of nuclei per blastocyst (39.7 vs. 19.8) were significantly higher (P < 0.05) in early- (before 24 hr) compared to late- (between 24 and 48 hr) cleaving embryos after PA. CC3 was mainly detected in the cytoplasm of Day-2 and -4 embryos, but was primarily localized in the nucleus of Day-5 and -6 embryos. The fluorescence signal for CC3 relative to negative controls was significantly higher (P < 0.05) in early- (2.42-fold) compared to late-cleaving (1.39-fold) embryos at Day 2 of culture. Treatment with z-DEVD-fmk during the first 24 or 48 hr of the culture period resulted in more embryos developing into blastocysts compared to the control group (55.8% and 55.1% vs. 37%, respectively; P < 0.05). This study confirmed the presence of CC3 in PA embryos from the two-cell to the blastocyst stage, and revealed that CC3 cellular-localization changed during embryo development. CC3 was shown to be more abundant in early-cleaving and more developmentally competent embryos compared to late-cleaving and less developmentally competent embryos. The inhibition of caspase activity at the beginning, but not at the end, of the culture period affected development of PA embryos.

In vivo oocyte developmental competence is reduced in lean but not in obese superovulated dairy cows after intraovarian administration of IGF1

The present study investigated the role of IGF1 in lactating lean and non-lactating obese dairy cows by injecting 1 μg IGF1 into the ovaries prior to superovulation. This amount of IGF1 has been linked with pregnancy loss in women with the polycystic ovary syndrome (PCOS) and was associated with impaired bovine oocyte competence in vitro. Transcript abundance and protein expression of selected genes involved in apoptosis, glucose metabolism, and the IGF system were analyzed. Plasma concentrations of IGF1 and leptin, and IGF1 in uterine luminal fluid (ULF), were also measured. IGF1 treatment decreased embryo viability in lean cows to the levels observed in obese cows. Obese cows were not affected by IGF1 treatment and showed elevated levels of IGF1 (in both plasma and ULF) and leptin. Blastocysts from lean cows treated with IGF1 showed a higher abundance of SLC2A1 and IGFBP3 transcripts. IGF1 treatment reduced protein expression of tumor protein 53 in blastocysts of lean cows, whereas the opposite was observed in obese cows. IGF1 in plasma and ULF was correlated only in the control groups. Blastocyst transcript abundance of IGF1 receptor and IGFBP3 correlated positively with IGF1 concentrations in both plasma and ULF in lean cows. The detrimental microenvironment created by IGF1 injection in lean cows and the lack of effect in obese cows resemble to a certain extent the situation observed in PCOS patients, where IGF1 bioavailability is increased in normal-weight women but reduced in obese women, suggesting that this bovine model could be useful for studying IGF1 involvement in PCOS.

Evaluation of bovine zona pellucida characteristics in polarized light as a prognostic marker for embryonic developmental potential

It has previously been demonstrated that zona pellucida imaging of human oocytes using polarized light microscopy is a clinically applicable method for the noninvasive assessment of oocyte quality. This study was designed to investigate whether zona pellucida characteristics of bovine oocytes and zygotes in polarized light may similarly serve as a useful marker for developmental competence in bovine reproductive biotechnologies. Zona birefringence intensity parameters of 2862 oocytes/zygotes were objectively evaluated with an automatic analysis system and correlated with oocyte/zygote quality. In detail, immature oocytes of good quality assessed with brilliant cresyl blue staining showed significantly lower zona birefringence than poor-quality counterparts (P<0.001). After in vitro maturation and classification according to maturational status, the birefringence intensity parameters were significantly different in those oocytes that reached metaphase II compared with arrested stages (P<0.001). Following either parthenogenetic activation or IVF with subsequent in vitro culture in a well-of-the-well system until day 9, superior development as determined by cleavage, blastocyst formation, and hatching ability was associated with lower zona birefringence intensity parameters. When early zygote-stage embryos were selected and assorted in groups based on zona birefringence (high/medium/low), the group of embryos derived from high-birefringence zygotes displayed a significantly compromised developmental potential compared with low-birefringence zygotes. These results clearly show that developmentally competent bovine oocytes/zygotes exhibit lower zona birefringence intensity parameters. Therefore, birefringence imaging of zona pellucida is a suitable technique to predict bovine preimplantation embryo development.

Anti-Müllerian hormone: a predictive marker of embryo production in cattle?

In cattle, the embryo production rate after superovulation varies between individuals and is difficult to predict. Recently, we proposed that anti-Müllerian hormone (AMH) plasma levels measured before treatment can help predict superovulatory responses. To establish whether blood measurement of AMH can help predict the number of embryos produced by a given cow after superovulation, data collected over 4 years from 45 dairy cows submitted to repeated embryo production were analysed in a retrospective study. A high within-animal repeatability (0.38 and 0.36) and a strong effect of the father of the donor cow (P < 0.01) were observed for the numbers of collected and transferable embryos, respectively. AMH concentration, measured in the plasma of donor cows during first lactation and several months before the start of the embryo production campaigns, was found to be highly correlated with the maximal number of collected (P < 0.0001) and transferable (P < 0.01) embryos per cow. In conclusion, the capacity of embryo production is a repeatable and probably heritable trait in the cow, and blood measurement of AMH in potential donor cows could be of value in determining a cow’s intrinsic capacity to produce transferable embryos.

Transforming growth factor-β1 inhibits luteinization and promotes apoptosis in bovine granulosa cells

We have previously shown that TGFB1 inhibits estradiol (E2) and progesterone (P4) biosynthesis in FSH-stimulated bovine granulosa cells by selective inhibition of steroidogenic enzymes. The objective of this study was to assess the effects of TGFB1 on E2and P4steroidogenesis in bovine granulosa cells cultured in the absence of FSH and to measure the effects of TGFB1 on cell proliferation and apoptosis in the presence and absence of FSH. Bovine granulosa cells from 2 to 5 mm follicles were cultured in serum-free medium for 2–6 days. In the absence of FSH, the secretion of P4increased with time in culture (P<0.05). Addition of TGFB1 for 6 days decreased P4secretion and mRNA levels of the P4synthesis-associated genesSTAR,CYP11A1,HSD3B1, andGSTA(P<0.05). In the absence of FSH, the secretion of E2decreased and addition of TGFB1 for 6 days partially reversed this decline and stimulated E2biosynthesis,CYP19A1andHSD17B1mRNA levels and CYP19A1 activity (P<0.05). Conversely, TGFB1 did not affectHSD17B7expression and HSD17B-reducing activity. TGFB1 decreased the proportion of cells in the G0/G1 and S+G2/M phases in FSH-stimulated and unstimulated granulosa cells (P<0.05). Furthermore, in the presence or absence of FSH, TGFB1 increased the proportion of cells in apoptosis measured by propidium iodide staining and flow cytometry and confirmed by increased levels of cleaved caspase-3 (P<0.05). Our results therefore indicate that TGFB1 inhibits luteinization in cultured bovine granulosa cells while maintaining an estrogenic phenotype, and this effect was associated with increased apoptosis.

The role of IGF1 in the in vivo production of bovine embryos from superovulated donors

IGF1 plays an important role in bovine follicular growth, acquisition of oocyte competence and embryo viability. Current data also indicate a critical role for IGF1 in both the ovarian response and the embryo yield following the superovulatory treatments. IGF1 can have either positive or negative effects on embryo viability which is related to the concentration of IGF1 induced by superovulation treatment. These effects impact either on oocyte competence or directly on the embryo. Concentrations in the physiological range appear to result in the production of higher quality embryos, mainly due to the mitogenic and the anti-apoptotic activities of IGF1. However, high superovulatory responses are associated with decreased embryo viability and a concomitant increase in apoptosis. Studies in mice suggest that this increase in apoptosis is related to the downregulation of the IGF1 receptor in the embryo associated with high IGF1 concentrations. Strategies capable of controlling the IGF1 concentrations could be one approach to improve superovulation responses. A range of possible approaches for research within the IGF system in gonadotrophin-stimulated cattle is discussed in this review, including the possible use of superovulated female cattle as an alternative animal experimental model for research on reproductive disorders in humans associated with abnormal IGF1 concentrations.

Phenotypes of the ovarian follicular basal lamina predict developmental competence of oocytes

BACKGROUND

The ovarian follicular basal lamina underlies the epithelial membrana granulosa and maintains the avascular intra-follicular compartment. Additional layers of basal lamina occur in a number of pathologies, including pili annulati and diabetes. We previously found additional layers of follicular basal lamina in a significant percentage of healthy bovine follicles. We wished to determine if this phenomenon existed in humans, and if it was related to oocyte function in the bovine.

METHODS AND RESULTS

We examined follicles from human ovaries (n = 18) by electron microscopy and found that many follicles had additional layers of basal lamina. Oocytes (n = 222) from bovine follicles with normal or unusual basal laminas were isolated and their ability to undergo in vitro maturation, fertilization and culture to blastocyst was compared. Healthy bovine follicles with a single layer of basal lamina had oocytes with significantly (P < 0.01) greater developmental competence than healthy follicles with additional layers of follicular basal lamina (65% versus 28%).

CONCLUSIONS

These findings provide direct evidence that the phenotype of the follicular basal lamina is related to oocyte competence.

The effect of mifepristone on apoptosis and caspase-3 activation in human ovarian luteinized granulosa cells

OBJECTIVE

To investigate the effect of mifepristone, an oral contraceptive, on apoptosis in human ovarian luteinized granulosa cells.

STUDY DESIGN

Human ovarian luteinized granulosa cells were treated in vitro with 1.25, 2.5, 5.0, 10.0, or 20.0 microM of mifepristone. Nuclear morphology, apoptosis ratio, and level of caspase-3 expression were determined with immunofluorescence microscopy, the terminal deoxynucleotidyl transferase mediated nick end labeling (TUNEL) assay, and flow cytometry.

RESULTS

We found that mifepristone-treated cells contained single condensed chromatin with multiple nuclear fragments, which is morphologic evidence of apoptosis. A significant difference was observed in the TUNEL assay between mifepristone-treated cells and control cells (P<0.05). Consistent with the results of the TUNEL assay, the fluorescence intensity of caspase-3 in drug-treated cells was also significantly different (P<0.05) from control cells; specifically, the difference between cells treated with different doses of drugs was much smaller and negligible.

CONCLUSION

From these results, we propose that mifepristone induces human ovarian luteinized granulosa cells to undergo apoptosis by activating caspase-3.

In vitro ageing of pig oocytes: effects of the histone deacetylase inhibitor trichostatin A

After in vitro maturation, the unfertilized pig oocytes underwent the process called ageing. This process involves typical events such as fragmentation, spontaneous parthenogenetic activation or lysis. Inhibition of histone deacetylase, using its specific inhibitor trichostatin A (TSA), significantly delayed the maturation of pig oocytes cultured in vitro. The ageing of oocytes matured under the effect of TSA is the same as the ageing in oocytes matured without TSA. The inhibition of histone deacetylase during oocyte ageing significantly reduced the percentage of fragmented oocytes (from 30% in untreated oocytes to 9% in oocytes aged under the effect of 100 nM of TSA). Oocytes matured in vitro and subsequently aged for 1 day under the effects of TSA retained their developmental capacity. After parthenogenetic activation, a significantly higher portion (27% vs. 15%) of oocytes developed to the blastocyst stage after 24 h ageing under 100 nM TSA when compared with oocytes activated after 24 h ageing in a TSA-free medium. The parthenogenetic development in oocytes aged under TSA treatment is similar to the development of fresh oocytes (29% of blastocyst) artificially activated immediately after in vitro maturation.

Interactions among activity of glucose-6-phosphate dehydrogenase in immature oocytes, expression of apoptosis-related genes Bcl-2 and Bax, and developmental competence following IVP in cattle

This study was conducted to understand whether the level of G6PDH activity assessed in immature bovine oocytes by means of BCB test was correlated with the level of expression of apoptosis-related genes such as Bcl-2 and Bax in immature and mature oocytes. This information should support previous findings suggesting that G6PDH activity is a useful marker for determining oocyte quality, thereby increasing the validity of BCB test in oocyte selection. Up to now, there are no data estimating the relation between G6PDH activity and the expression of apoptosis-related genes in oocytes. The expression of Bcl-2 and Bax genes was estimated on the mRNA and protein levels, respectively using real-time PCR and Western-blotting. To evaluate developmental competence of these oocytes, cumulus-oocyte complexes classified as BCB+ (low activity of G6PDH), BCB- (high activity of G6PDH) and Control were used for in vitro embryo production. In immature oocytes, the Bax transcript level in BCB- oocytes was significantly higher (P<0.001) in comparison to Control. In mature oocytes, the Bcl-2 transcript level was significantly lower in BCB+ oocytes (P<0.01) and in BCB- oocytes (P<0.05) in comparison to Control. However, no relation was found between the activity of G6PDH and the expression of the Bcl-2 or Bax proteins, both in immature and mature oocytes. Our results on the transcript level seem to indicate that oocytes subjected to BCB staining show tendency towards apoptosis. However, results obtained at the protein level did not confirm this conclusion. The usefulness of the BCB test as the indirect marker of apoptosis seems to be questionable. The lack of significant differences in the blastocyst rates developed from BCB+ and Control oocytes decreases the validity of BCB test in IVP technology.

Invited review: New perspectives on the roles of nutrition and metabolic priorities in the subfertility of high-producing dairy cows

Management, nutrition, production, and genetics are the main reasons for the decline in fertility in the modern dairy cow. Selection for the single trait of milk production with little consideration for traits associated with reproduction in the modern dairy cow has produced an antagonistic relationship between milk yield and reproductive performance. The outcome is a multi-factorial syndrome of subfertility during lactation; thus, to achieve a better understanding and derive a solution, it is necessary to integrate a range of disciplines, including genetics, nutrition, immunology, molecular biology, endocrinology, metabolic and reproductive physiology, and animal welfare. The common theme underlying the process is a link between nutritional and metabolic inputs that support complex interactions between the gonadotropic and somatotropic axes. Multiple hormonal and metabolic signals from the liver, pancreas, muscle, and adipose tissues act on brain centers regulating feed intake, energy balance, and metabolism. Among these signals, glucose, fatty acids, insulin-like growth factor-I, insulin, growth hormone, ghrelin, leptin, and perhaps myostatin appear to play key roles. Many of these factors are affected by changes in the somatotropic axis that are a consequence of, or are needed to support, high milk production. Ovarian tissues also respond directly to metabolic inputs, with consequences for folliculogenesis, steroidogenesis, and the development of the oocyte and embryo. Little doubt exists that appropriate nutritional management before and after calving is essential for successful reproduction. Changes in body composition are related to the processes that lead to ovulation, estrus, and conception. However, better indicators of body composition and measures of critical metabolites are required to form precise nutritional management guidelines to optimize reproductive outcomes. The eventual solution to the reduction in fertility will be a new strategic direction for genetic selection that includes fertility-related traits. However, this will take time to be effective, so, in the short term, we need to gain a greater understanding of the interactions between nutrition and fertility to better manage the issue. A greater understanding of the phenomenon will also provide markers for more targeted genetic selection. This review highlights many fruitful directions for research, aimed at the development of strategies for nutritional management of reproduction in the high-producing subfertile dairy cow.

Evaluation of oocyte quality: morphological, cellular and molecular predictors

Mounting evidence that oocyte quality profoundly affects fertilisation an d subsequent embryo development drives the continued search for reliable predictors of oocyte developmental competence. In the present review, we provide an overall summary and analysis of potential criteria that can be used to evaluate oocyte quality. These criteria are specifically classified as morphological and cellular/molecular predictors. Traditional methods for the evaluation of oocyte quality are based on morphological classification of thefollicle, cumulus-oocytecomplex, polar body and/or meiotic spindle. Although the use of morphological characteristics as predictors of oocyte quality is controversial, such a grading system can provide valuable information for the preselection of oocytes with higher developmental competence and, therefore, may maximise embryo developmental outcome. Several intrinsic markers (such as mitochondrial status and glucose-6-phosphate dehydrogenase 1 activity) and extrinsic markers (such as apoptosis of follicular cells and levels of the transforming growth factor-beta superfamily in follicular fluid or serum) have also been reported as useful indicators of oocyte competence and embryo quality. Compared with the morphological parameters, these cellular and molecular predictors of oocyte quality may prove to be more precise and objective, although further studies and refinement of techniques are needed.

Gamete origin in relation to early embryo development

Fertilization in vivo requires a complex series of selection events to occur in order to guarantee that only the fittest gametes take part in the fusion process and give rise to a viable embryo. Conventional practice in bovine in vitro fertilization however is to select oocytes and sperm by quite crude procedures. It is therefore not inconceivable that essentially unfit gametes may drive aberrant embryo development in vitro. Abnormal embryonic cells are being removed by apoptosis, which is a physiological process in embryos. Only an excess or a lack of apoptosis can lead to embryonic death or abnormal development. Suboptimal culture conditions undoubtedly contribute to undue embryonic apoptosis, but the intrinsic quality of the oocyte may also be a causative factor. It is generally accepted that the oocyte is in control of early embryogenesis, but is it also in control of future embryonic suicide? Is a compromised follicular environment predestining the oocyte to a dire fate? What is the contribution of the cumulus cells to oocyte quality, and can they rescue it from early demise? And what can be said about the origin of the spermatozoa? Research in human in vitro fertilization has definitely shown that factors such as paternal age, smoking and other sperm stressors can contribute to abnormal embryo development and even diseased offspring. This review will address the questions raised above, and will describe what is known about the cellular and molecular biology that may account for abnormal bovine embryo development caused by gamete origin.

Impact of dietary fatty acids on oocyte quality and development in lactating dairy cows

The purpose of this study was to examine the effects of level of rumen inert fatty acids on developmental competence of oocytes in lactating dairy cows. Estrous cycles were synchronized in 22 cows on a silage-based diet supplemented with either low (200 g/day) or high (800 g/day) fat. A total of 1051 oocytes were collected by ultrasound-guided ovum pickup (OPU) in seven sessions/cow at 3-4 day intervals. Oocytes were matured, fertilized, and cultured to the blastocyst stage in vitro. Embryo quality was assessed by differential staining of Day 8 blastocysts. The high-fat diet reduced numbers of small and medium follicles. There was no effect on the quality of oocytes (grades 1-4) or cleavage rate. However, high fat significantly improved blastocyst production from matured (P < 0.005) and cleaved (P < 0.05) oocytes. Blastocysts from the high-fat group had significantly more total, inner cell mass and trophectoderm cells than the low-fat group (P < 0.05). Regression analysis showed negative effects of milk yield (P < 0.001), dry matter intake (P < 0.001), metabolizable energy intake (P < 0.005), and starch intake (P < 0.001) on blastocyst production in the low-fat group but not in the high-fat group. Within the low-fat group, blastocyst production was negatively related to growth hormone (P < 0.05) and positively related to leptin (P < 0.05). The low-fat group had higher nonesterified fatty acids than the high-fat group (P < 0.05). In conclusion, higher milk yields were associated with reduced developmental potential of oocytes in cows given a low-fat diet. Provision of a high-fat diet buffered oocytes against these effects, resulting in significantly improved developmental potential.

Developmental competence of bovine oocytes is not related to apoptosis incidence in oocytes, cumulus cells and blastocysts

The number of follicles undergoing atresia in an ovary is very high, and isolation of cumulus-oocyte complexes (COCs) from such atretic follicles may impair subsequent embryo development in vitro. Our aim was to study if stringent selection by morphological assessment of COCs can improve embryo development, and to evaluate whether oocyte diameter is related with apoptotic ratio in oocytes and blastocysts. COCs from slaughtered cattle were recovered by follicle aspiration and classified depending on oocyte diameter: (A) <110 microm; (B) 110-120 microm; (C) >120 microm. COCs were matured, fertilized and cultured in vitro. Early and late stages of apoptosis were detected by Annexin-V and TUNEL staining, respectively, in denuded oocytes, COCs and blastocysts. Immature oocytes from Group A showed higher apoptotic ratio assessed by TUNEL assay, and the COCs corresponding to this group also showed a higher proportion of apoptotic cumulus cells. After maturation, no differences were present in the incidence of apoptosis among oocytes from different groups, but COCs corresponding to the largest diameter showed less apoptotic cumulus cells. In addition, the percentage of apoptotic oocytes decreased during in vitro maturation in all groups. Apoptotic cell ratio (ACR) in blastocysts was not related to oocyte diameter. In conclusion, oocyte selection and oocyte morphological evaluation prior to maturation was not sufficient to select non-atretic oocytes. When oocyte diameter was used as an additional selection the embryonic developmental potential increased together with oocyte diameter, but this improvement was not related to a lower incidence of apoptosis in the largest oocytes.

Apoptosis Inhibition by Insulin-Like Growth Factor (IGF)-I During In Vitro Maturation of Bovine Oocytes

Recently, significant progress has been achieved in improving the yield of good quality embryos in vitro. However, efforts are still required to recognize the factors and understand the mechanisms of oocyte maturation, which are essential for subsequent embryo development. The aims of the present study were to determine the frequency of apoptosis in oocytes recovered from slaughterhouse ovaries and to investigate whether insulin-like growth factor (IGF)-I action during oocyte maturation in vitro may withhold apoptosis and improve oocyte quality. Only oocytes of proper morphology with homogenous ooplasm and compact cumulus cells were selected for this study. All oocytes recovered from the slaughterhouse ovaries were divided into two groups. One group of oocytes, chosen for apoptosis detection, was examined immediately after recovery. The other group of oocytes was maturated in vitro. Oocytes were maturated with IGF-I supplementation (100 ng/ml). Oocytes without supplementation were used as a control. Apoptosis in oocytes was determined by positive results of TUNEL assay and active caspase labeling. The percentage of apoptotic oocytes detected by TUNEL fell to zero when the maturation medium was supplemented with IGF-I in comparison to the control matured oocytes (0 vs. 9.87%; P<0.05). However, active caspase labeling was only slightly decreased in the IGF-I matured oocytes compared with the control matured oocytes (1.13 vs. 2.08%; P<0.05). The results indicate that IGF-I may serve as an anti-apoptotic factor during oocyte maturation. We suggest that IGF-I may inhibit apoptosis in oocytes at the stage of caspase activation and may prevent further advancement of oocyte apoptosis.