Ancestral hymenopteran queen pheromones do not share the broad phylogenetic repressive effects of honeybee queen mandibular pheromone

Queen pheromones effect the reproductive division of labour, a defining feature of eusociality. Reproductive division of labour ensures that one, or a small number of, females are responsible for the majority of reproduction within a colony. Much work on the evolution and function of these pheromones has focussed on Queen Mandibular Pheromone (QMP) which is produced by the Western or European honeybee (Apis mellifera). QMP has phylogenetically broad effects, repressing reproduction in a variety of arthropods, including those distantly related to the honeybee such as the fruit fly Drosophila melanogaster. QMP is highly derived and has little chemical similarity to the majority of hymenopteran queen pheromones which are derived from cuticular hydrocarbons. This raises the question of whether the phylogenetically widespread repression of reproduction by QMP also occurs with more basal saturated hydrocarbon-based queen-pheromones. Using D. melanogaster we show that saturated hydrocarbons are incapable of repressing reproduction, unlike QMP. We also show no interaction between the four saturated hydrocarbons tested or between the saturated hydrocarbons and QMP, implying that there is no conservation in the mechanism of detection or action between these compounds. We propose that the phylogenetically broad reproductive repression seen in response to QMP is not a feature of all queen pheromones, but unique to QMP itself, which has implications for our understanding of how queen pheromones act and evolve.

Induction of Gonadal Development in Protogynous Grouper with Orally Delivered FSH DNA

The availability of sexually mature fish often dictates the success of its captive breeding. In this study, we induced reproductive development in juvenile protogynous tiger grouper through oral administration of a plasmid (p) containing an engineered follicle-stimulating hormone (FSH). An expression construct (pcDNA3.1) was designed to express a single-chain FSH consisting of giant grouper FSH β-subunit and glycoprotein subunit-α (CGα), linked by the carboxy-terminal peptide (CTP) sequence from the human chorionic gonadotropin (hCG). Single oral delivery of pFSH encapsulated in liposome and chitosan to tiger grouper yielded a significant increase in plasma FSH protein level after 4 days. Weekly pFSH feeding of juvenile tiger groupers for 8 weeks stimulated ovarian development as indicated by a significant increase in oocyte diameter and progression of oocytes to cortical alveolar stage. As the pFSH treatment progressed from 20 to 38 weeks, female to male sex change was initiated, characterized by oocyte regression, proliferation of spermatogonial cells, and occurrence of spermatogenic cysts. It was also associated with significantly lower mRNA expression of steroidogenic genes (cyp11b, cyp19a1a, and foxl2) and basal plasma levels of sex steroid hormones 17β-estradiol (E₂), testosterone (T), and 11-ketotestosterone (11KT). Results suggest that pFSH stimulates ovarian development up to cortical alveolar stage and then initiates sex change in tiger grouper. These findings significantly contribute to our knowledge on the role of FSH in the development of protogynous hermaphroditic fish. This study is the first to demonstrate induction of reproductive development in fish through oral delivery of plasmid gonadotropin.

Fluorene-9-bisphenol exposure induces cytotoxicity in mouse oocytes and causes ovarian damage

Fluorene-9-bisphenol (BHPF), a substitute for bisphenol A, is a chemical component of plastics for industrial production. There is evidence that BHPF exerts an antioestrogenic effect on mice, induces endometrial atrophy and leads to adverse pregnancy outcomes. However, the effects of BHPF on oocyte maturation and ovary development as well as its possible mechanisms remain unclear. The objective of this study was to investigate the toxicity and mechanism of BHPF exposure in mouse oocytes in vitro and in vivo. Our results showed that BHPF could inhibit the maturation of oocytes in vitro by reducing the protein level of p-MAPK and destroying the meiotic spindle. We found that in vitro, BHPF-treated oocytes showed increased ROS levels, DNA damage, mitochondrial dysfunction, and expression of apoptosis- and autophagy-related genes, such as Bax, cleaved-caspase 3, LC 3 and Atg 12. In addition, in vivo experiments showed that BHPF exposure could induce the expression of oxidative stress genes (Cat, Gpx 3 and Sod 2) and apoptosis genes (Bax, Bcl-2 and Cleaved-caspase 3) and increase the number of atresia follicles in the ovaries. Our data showed that BHPF exposure affected the first polar body extrusion of oocytes, increased oxidative stress, destroyed spindle assembly, caused DNA damage, altered mitochondrial membrane potentials, induced apoptosis and autophagy, and affected ovarian development.

Insulin-like growth factor binding proteins inhibit oocyte maturation of zebrafish

The function of insulin-like growth factor (Igf) system in ovary has attracted much attention, but the role of Igf binding proteins (Igfbps) in ovary is still largely unknown. In this study, the role of Igfbps in oocyte maturation was investigated in zebrafish. The expression of all eight identified Igfbps except Igfbp6b could be detected in the adult ovary and exhibited differential expression profiles during folliculogenesis. The expression of several Igfbps is dynamically changed during oocyte maturation induced by human chorionic gonadotropin (hCG). By treatment of an Igfbps inhibitor NBI-31772 in vitro, the oocyte maturation could be stimulated in a clear dose-, time- and stage-dependent manner. Such effects were also observed by administration of NBI-31772 in vivo. Igfbps are differentially expressed in both follicular cells and oocytes, but the effect of NBI-31772 could only be found in intact follicles and not in the denuded oocytes. Previous studies have demonstrated that Igf3 is the major Igf member in regulating oocyte maturation of zebrafish. Interestingly, NBI-31772 could increase the effect of Igf3 on oocyte maturation. Furthermore, we found the effect of NBI-31772 on oocyte maturation could be blocked by an Igf type 1 receptor inhibitor BMS-536924 in vitro, suggesting the Igfbps can inhibit the oocyte maturation via Igf/Igf1r pathway. Together, we provided the first evidence in fish that Igfbps inhibit oocyte maturation of zebrafish.

Dosage-related beneficial and deleterious effects of ginsenoside Rb1 on mouse oocyte maturation and fertilization and fetal development

Ginsenoside Rb1 (GRb1), the major saponin component of ginseng root, has a wide range of therapeutic applications for various diseases. Previously, our group showed that GRb1 triggers ROS-mediated apoptotic cascades in mouse blastocysts, leading to decreased cell viability and impairment of pre- and postimplantation embryonic development, both in vitro and in vivo. In this study, we further found that GRb1 exerted dose-dependent effects on oocyte maturation and sequent development in vitro. Oocytes preincubated with 25 μg/mL GRB1 displayed significantly enhanced maturation and in vitro fertilization (IVF) rates, along with progression of subsequent embryonic development. In contrast, treatment with 50 and 100 μg/mL GRB1 led to impairment of mouse oocyte maturation, decreased IVF rates, and injurious effects on subsequent embryonic development. In vivo, intravenous injection of 1 mg/kg body weight GRb1 significantly promoted mouse oocyte maturation, IVF, and early-stage embryo development after fertilization while administration of 5 mg/kg body weight GRb1 led to a marked decrease in oocyte maturation and IVF rates concomitant with impairment of early embryonic development in our animal model. In terms of the mechanisms underlying the regulatory effects of GRb1 demonstrated increased intracellular reactive oxygen species (ROS) production and apoptosis in the 100 μg/mL GRb1 treatment group. However, we observed a significant decrease in total intracellular ROS content and inhibition of apoptosis events in the 25 μg/mL GRb1 treatment group, signifying that the intracellular ROS content serves as a key upstream regulator of GRb1 that influences its dose-dependent beneficial or deleterious effects on oocyte maturation and sequent embryonic development. For further clarification of the mechanisms underlying GRb1-triggered injurious effects, oocytes were pretreated with Ac-DEVD-CHO, a caspase-3-specific inhibitor, which effectively blocked injury to oocyte maturation, fertilization, and sequent development. In sum, study findings highlight the potential involvement of p53-, p21-, and caspase-3-dependent regulatory signaling cascades in GRb1-mediated apoptotic processes.

Follicular dynamics and in vivo embryo production in Santa Inês ewes treated with smaller doses of pFSH

To evaluate follicular dynamics, there was assessment of superovulatory response and in vivo embryo production in ewes treated with relatively smaller doses of exogenous pFSH than typically used in combination with a dose of eCG at the beginning of the gonadotropin treatment period. Santa Inês ewes (n = 24) were randomly divided into three groups, based on mg dose of pFSH administered: G200 (n = 8), G133 (n = 8) and G100 (n = 8) in eight decreasing doses at 12 -h intervals. All ewes were treated with 300 IU of eCG concomitantly starting with first pFSH administration. Ovulatory follicular dynamics and follicular wall vascularization (FWV) were evaluated using a B-mode and color Doppler ultrasonic machine, respectively. Superovulatory response and embryo production were evaluated 6 days after estrous detection. In the G200 group, the preovulatory follicle size (PFS) were less (P <  0.05), ovulation time later (P <  0.05), and PFS rate greater (P <  0.05); while in the G100 group ovulation rate, and number and percentage of unfertilized eggs were greater (P <  0.05) than in the G133 group (P <  0.05). Number and percentage of viable embryos were greater in the G200 and G100 compared to G133 group (P <  0.05). The dose of 100 mg of FSH was as efficacious as the traditional dose of 200 mg, in combination with a dose of eCG, for superovulatory response and viable embryo production but there was a greater percentage of unfertilized eggs with this treatment.

Modulatory Effects of Single and Complex Vitamins on the In Vitro Growth of Murine Ovarian Follicles

Background

Vitamin is a well-known co-factor for many metabolic processes and its roles in fertility and follicular growth have been studied. Vitamin supplementation is frequently achieved by daily ingestion in the form of a complex capsule. However, the role of single and complex vitamins in in vitro maturation of murine follicles is not fully elucidated.

Methods

In this study, we evaluated the effects of two forms of vitamins. Pure L-ascorbic acid, and multi-vitamin (vitamin C + vitamin B complex) was treated at two different concentrations (50 and 100 µg/ml), to pre-puberty murine follicles during in vitro maturation. To determine the specific stage of growth that is affected by treatment with vitamins, the vitamins were treated from day 0, 4, 9, and 13. Growth of each follicle was assessed by measuring diameters of whole expanded area and of the granulosa cells. Expression of follicular and oocyte growth-related genes and the effect of vitamin on the viability of follicles was assessed using senescence associated β-galactosidase staining.

Results

Treatment with vitamins promoted the in vitro growth of murine follicles and the upregulated the expression of granulosa cell- and oocyte-specific genes such as BMP15, Fsh receptor, and GDF9. The proliferation of the granulosa cells was enhanced by the treatment of vitamin. Fifty µg/ml concentration vitamin showed greater effects compared to higher concentration. The viability of in vitro grown follicles was also significantly improved in vitamin-treated follicles. The effects of single L-ascorbic acid and complex vitamin were not significantly different to those of day 4 and day 9 follicles. Vitamins promoted murine follicle development in vitro with different effects on specific growth stage.

Conclusion

Supplementation of vitamins during in vitro maturation of murine follicles is an efficient strategy for in vitro expansion of follicular cells. These results could be customized to the sophisticated culture of follicles retrieved from aged or cancer-survived female that contain smaller number of follicles with reduced potential to develop into mature follicles.

Atrazine or bisphenol A mediated negative modulation of mismatch repair gene, mlh1 leads to defective oogenesis and reduced female fertility in Drosophila melanogaster

The study reports the effects of an herbicide (atrazine) and a plasticizer (Bisphenol A, BPA) on the transcriptional modulation of a mismatch repair gene (mlh1) and its adverse consequences on female fertility using Drosophila as a model. Through a chemical screen, we show that exposure to atrazine or BPA significantly downregulates mlh1 and the exposed flies had reduced fertility with smaller ovaries having reduced number of mature oocytes and abnormal distribution of ovarian follicles with increased apoptosis in them. These females had increased double-strand breaks as well as reduced synaptonemal complex formation in their ovaries suggesting altered meiotic crossing over. The eggs of these females were defective in their maternal transcripts as well as proteins and consequently, after fertilization, these eggs exhibited abnormal embryonic development. Interestingly, these phenotypes parallel that of mlh1 mutants. Further, exposure of females having reduced Mlh1 levels (mlh1^e00130/CyO) to atrazine or BPA caused severe defective phenotypes at a higher proportion than normal flies. Our findings reveal the critical role of mlh1 in atrazine and BPA mediated female reproductive toxicity, and opens up a possibility of toxicants affecting female fertility by modulating the MMR genes.

Exposure to MPA-capped CdTe quantum dots causes reproductive toxicity effects by affecting oogenesis in nematode Caenorhabditis elegans

Quantum dots (QDs), considered as a type of excellent semiconductor nanomaterial, are widely employed and have a number of important applications. However, QDs have the potential to produce adverse effects and toxicity with the underlying molecular mechanisms not well understood. Herein, Caenorhabditis elegans was used for in vivo toxicity assessment to detect the reproductive toxicity of CdTe QDs. We found that exposure to CdTe QDs particles (≥ 50 mg/L) resulted in a defect in reproductive capacity, dysfunctional proliferation and differentiation, as well as an imbalance in oogenesis by reducing the number of cells in pachytene and diakinesis. Further, we identified a SPO-11 and PCH-2 mediated toxic mechanism and a GLP-1/Notch mediated protective mechanism in response to CdTe QDs particles (≥ 50 mg/L). Taken together, these results demonstrate the potential adverse impact of CdTe QDs (≥ 50 mg/L) exposure on oogenesis and provide valuable data and guidelines for evaluation of QD biocompatibility.

Chlorothalonil inhibits mouse ovarian development through endocrine disruption

Although many studies have investigated the toxic effects and even the reproductive toxicity of chlorothalonil, almost no studies have focused on the ovary, the organ of oocyte development. Puberty is a critical window for development of the female reproductive system. Therefore, this investigation aimed to explore the effects and underlying mechanisms of chlorothalonil at low doses on peripubertal mouse ovarian development. Chlorothalonil is frequently used in horticulture with short intervals between applications, therefore, vegetables and fruits may be potential sources of chlorothalonil contamination. For the first time, this study demonstrated that chlorothalonil inhibited ovarian development during puberty in mice, and at levels currently assumed to have no adverse health consequences for humans. Chlorothalonil exposure inhibited mouse ovarian development by increasing the number of primary follicles and decreasing the number of mature follicles. It acted by decreasing the levels of hormone production proteins, such as FSH receptor and estrogen receptor alpha, while increasing the levels of DNA repairing marker RAD51 and cell apoptosis. These results suggest that chlorothalonil may disrupt endocrine function and inhibit murine ovarian development. Therefore it may pose a potential health risk to female reproductive systems in other species, especially to the ovary.

Mitochondrial respiratory chain complex abnormal expressions and fusion disorder are involved in fluoride-induced mitochondrial dysfunction in ovarian granulosa cells

Excessive fluoride intake has a strong female reproductive toxicity, which can result in follicular developmental dysplasia and decrease oocytes developmental potential. The underlying mechanisms of fluoride-induced mitochondrial dysfunction in ovarian granulosa cells remain largely unknown. In this study, the ultrastructure changes of mitochondria and DNA damage in ovarian granulosa cells were observed under transmission electron microscope and TUNEL staining. Then, the ATP content and ROS level in granulosa cells were measured. The expression of mitochondrial fusion proteins and mitochondrial respiratory chain complexes, including OPA1 and Mfn1, and NDUFV2, SDHA and CYC1, in the ovarian tissues were measured by immunohistochemistry, Western blot and Quantitative real-time PCR analyses. The expression of ATP5j and ATP5h in the ovarian tissues was also measured. Results show that fluoride treatment considerably damages mitochondrial ultrastructure and enhances the apoptosis of granulosa cells. The ATP content greatly decreased, whereas the ROS level increased after fluoride treatment. The expression level of Mfn1 in the ovarian tissue was up-regulated, whereas OPA1 expression had no significant change. The expression levels of NDUFV2, SDHA and CYC1 were considerably up-regulated, and the expression of ATP5j and ATP5h were down-regulated after fluoride treatment. In summary, the damage in the mitochondrial ultrastructure, ATP content decrease, ROS level increase and the abnormal expression of OPA1, Mfn1, NDUFV2, SDHA, CYC1, ATP5j and ATP5h in ovary tissue are closely associated with fluoride-induced mitochondrial dysfunction, which might be responsible for the follicular developmental dysplasia and the potential decrease in oocyte development induced by fluoride in female mice.

Roles of Figla/figla in Juvenile Ovary Development and Follicle Formation During Zebrafish Gonadogenesis

Sex determination and differentiation are complex processes. As a juvenile hermaphrodite or undifferentiated gonochorist, zebrafish undergo a special juvenile ovarian phase during sex differentiation, making it an excellent model for studying early oogenesis and folliculogenesis. We provide lines of evidence at morphological, molecular, and genetic levels for roles of factor in the germline α (Figla), an oocyte-specific transcription factor, in early zebrafish gonadogenesis. As in mammals, Figla/figla was also expressed in the gonads and its expression in the ovary was also restricted to early oocytes. Disruption of figla gene by CRISPR/Cas9 led to an all-male phenotype in the mutant. Detailed analysis of early gonadal development showed that the germ cells in the mutant were clustered in cysts and underwent meiosis, forming oocytes at prefollicular chromatin nucleolar (CN) stage (stage IA). However, the subsequent transition from cystic CN oocytes to individual follicular perinucleolar oocytes (stage IB) was blocked, resulting in an all-male phenotype in the mutant. The phenotype of figla mutant could not be rescued by estrogen treatment, in contrast to cyp19a1a mutant, and introduction of tp53 mutation also had no effect, unlike in fancd1 and fancl mutants. Transcriptome analysis revealed that many biological processes and pathways related to germ cell development, especially oogenesis, were upregulated in the presence of Figla and that the regulation of figla expression may involve heat shock proteins. Our results strongly suggest important roles for Figla in juvenile ovary development, especially the formation of individual follicles from cystic oocytes.

Does the bone morphogenetic protein 7 inhibit oocyte maturation by autocrine/paracrine in mud crab?

A bone morphogenetic protein ligand (BMP7) and its two receptors (BMPRIB and BMPRII) were recently cloned and characterized in the mud crab, Scylla paramamosain. However specific functions of BMP7 and the mechanistic pathways regulating its function are largely unidentified. In the present study, we separated oocytes and follicle cells from the ovarian explants of S. paramamosain. Subsequent analysis using semi-quantitative PCR demonstrated that the mRNA of Sp-BMP7 was exclusively expressed in follicle cells while Sp-BMPRs were expressed in both oocytes and follicle cells. In vitro experiments further showed that the mRNA and protein levels of Cyclin B increased but Sp-BMP7 declined in 17α, 20β-Dihydroxyprogesterone (DHP)-induced oocytes. Furthermore, the inhibitory effects of Sp-BMP7 were not affected by the elimination of the contact/gap junction-mediated communication between oocytes and follicle cells. Our data indicate that BMP7 may play a role in the suppression of DHP-induced oocyte maturation by affecting autocrine/paracrine pathways in S. paramamosain.

Role of natriuretic peptide receptor 2-mediated signaling in meiotic arrest of zebrafish oocytes and its estrogen regulation through G protein-coupled estrogen receptor (Gper)

Natriuretic peptide type C (NPPC) and its receptor, natriuretic peptide receptor 2 (NPR2), have essential roles in maintaining meiotic arrest of oocytes in several mammalian species. However, it is not known if a similar mechanism exists in non-mammalian vertebrates. Using zebrafish as a model, we show that Nppc is expressed in ovarian follicle cells, whereas Npr2 is mainly detected in oocytes. Treatment of intact and defolliculated oocytes with 100 nM NPPC for 6 h caused a large increase in cGMP concentrations, and a significant decrease in oocyte maturation (OM), an effect that was mimicked by treatment with 8-Br-cGMP. Treatment with E2 and G-1, the specific GPER agonist, also increased cGMP levels. Cyclic AMP levels were also increased by treatments with 8-Br-cGMP, E2 and G1. The estrogen upregulation of cAMP levels was blocked by co-treatment with AG1478, an inhibitor of EGFR activation. Gene expression of npr2, but not nppc, was significantly upregulated in intact oocytes by 6 h treatments with 20 nM E2 and G-1. Both cilostamide, a phosphodiesterase 3 (PDE3) inhibitor, and rolipram, a PDE4 inhibitor, significantly decreased OM of intact and defolliculated oocytes, and enhanced the inhibitory effects of E2 and G-1 on OM. These findings indicate the presence of a Nppc/Npr2/cGMP pathway maintaining meiotic arrest in zebrafish oocytes that is upregulated by estrogen activation of Gper. Collectively, the results suggest that Nppc through Npr2 cooperates with E2 through Gper in upregulation of cGMP levels to inhibit phosphodiesterase activity resulting in maintenance of oocyte meiotic arrest in zebrafish.

N-octanoylated ghrelin peptide inhibits bovine oocyte meiotic resumption

BACKGROUND

Studies have shown that ghrelin plays an important role in the mammalian reproductive system, including the central, gonadal levels, and also during in vitro maturation of oocytes; however, the functions of ghrelin in bovine oocyte meiosis require further investigation.

OBJECTIVE

We aimed to evaluate the effects of an n-octanoylated ghrelin peptide on oocyte meiotic resumption and the developmental competence of mature oocytes in vitro.

EXPERIMENTAL

design: The expression of GHRL (encoding ghrelin) mRNA and its receptor (the growth hormone secretagogue receptor, GHSR) in the cumulus-oocyte complex (COCs), denuded oocytes (DOs), and cumulus cells (CCs) was assessed using quantitative real-time reverse transcription PCR (qRT-PCR), and the effects of the n-octanoylated ghrelin peptide on meiotic resumption were studied at four different doses (0, 10, 50, and 100 ng/mL) in a 6 h culture system.

RESULTS

qRT-PCR analysis showed that GHRL and GHSR mRNAs were expressed in all tested samples; however, GHRL was predominantly expressed in DOs, and GHSR was predominantly expressed in CCs. Germinal vesicle breakdown was inhibited significantly by 50 ng/mL ghrelin compared with that in the negative control (P < 0.05). Further studies showed that n-octanoylated ghrelin increased the levels of cAMP and cGMP in the CCs and DOs, which inhibited the meiotic resumption of bovine oocytes. And the inhibitory role in the developmental competence of mature oocytes were also included, ghrelin could significantly improve the cleavage rate (P < 0.05) and blastocyst rate (P < 0.05).

CONCLUSION

N-octanoylated ghrelin maintained bovine oocytes meiotic arrest and further improved their developmental competence; therefore, n-octanoylated ghrelin could be considered as a potential pharmaceutical inhibitor of meiosis for the in vitro maturation of bovine oocytes.

Tributyltin impaired reproductive success in female zebrafish through disrupting oogenesis, reproductive behaviors and serotonin synthesis

Tributyltin (TBT), an organotin acting as aromatase (Cyp19a1) inhibitor, has been found to disrupt gametogenesis and reproductive behaviors in several fish species. However, few studies addressing the mechanisms underlying the impaired gametogenesis and reproduction have been reported. In this study, female adults of zebrafish (Danio rerio) were continuously exposed to two nominal concentrations of TBT (100 and 500 ng/L, actual concentrations: 90.8 ± 1.3 ng/L and 470.3 ± 2.7 ng/L, respectively) for 28 days. After exposures, TBT decreased the total egg number, reduced the hatchability and elevated the mortality of the larvae. Decreased gonadosomatic index (GSI) and altered percentages of follicles in different developmental stages (increased early-stage follicles and reduced mid/late-stage follicles) were also observed in the ovary of TBT-treated fish. TBT also lowered the plasma level of 17β-estradiol and suppressed the expressions of cyp19a1a in the ovary. In treated fish, up-regulated expressions of aldhla2, sycp3 and dmc1 were present in the ovary, indicating an enhanced level of meiosis. The mRNA level of vtg1 was dramatically suppressed in the liver of TBT-treated fish, suggesting an insufficient synthesis of Vtg protein, consistent with the decreased percentage of mid/late-stage follicles in the ovaries. Moreover, TBT significantly suppressed the reproductive behaviors of the female fish (duration of both sexes simultaneously in spawning area, the frequency of meeting and the visit in spawning area) and down-regulated the mRNA levels of genes involved in the regulation of reproductive behaviors (cyp19a1b, gnrh-3 and kiss 2) in the brain. In addition, TBT significantly suppressed the expressions of serotonin-related genes, such as tph2 (encoding serotonin synthase), pet1 (marker of serotonin neuron) and kiss 1 (the modulator of serotonin synthesis), suggesting that TBT might disrupt the non-reproductive behaviors of zebrafish. The present study demonstrated that TBT may impair the reproductive success of zebrafish females probably through disrupting oogenesis, disturbing reproductive behaviors and altering serotonin synthesis. The present study greatly extends our understanding on the reproductive toxicity of TBT on fish.

Roles of progesterone receptor membrane component 1 and membrane progestin receptor alpha in regulation of zebrafish oocyte maturation

Although previous studies suggest membrane progesterone receptor alpha (mPRα/Paqr7) mediates 17, 20β-dihydroxy-4-pregnen-3-one (DHP) induction of oocyte maturation (OM) in zebrafish, critical information needed to establish mPRα as the receptor mediating OM is lacking. The relative potencies of progestins and specific mPRα agonists in inducing OM matched their relative binding affinities for zebrafish mPRα, supporting its role in OM. Microinjection of pertussis toxin blocked DHP induction of OM and the progestin-induced decrease in cyclic AMP levels, suggesting mPRα activates an inhibitory G protein (Gi). Microinjection of morpholino antisense oligonucleotides to zebrafish pgrmc1 blocked induction of OM by DHP which was accompanied by decreased levels of Pgrmc1 and mPRα on the oocyte plasma membranes. Similarly, treatment of denuded oocytes with a PGRMC1 inhibitor, AG205, blocked the gonadotropin-induced increase in plasma membrane mPRα levels and attenuated DHP induction of OM. Co-incubation with two inhibitors of epidermal growth factor Erbb2, ErbB2 inhibitor II and AG 879, prevented induction of OM by DHP, indicating the likely involvement of Erbb2 in mPRα-mediated signaling. Treatment with AG205 reversed the inhibitory effects of the Erbb2 inhibitors on OM and also inhibited insulin-like growth factor-1 induction of OM. Close associations between Pgrmc1 and mPRα, and between Pgrmc1 and Erbb2 were detected in zebrafish oocytes with in situ proximity ligation assays. The results suggest progestin induction of OM in zebrafish is mediated through an mPRα/Gi/Erbb2 signaling pathway that requires Pgrmc1 for expression of mPRα on oocyte membranes and that Pgrmc1 also is required for induction of OM through Erbb2.

Luteinizing Hormone Facilitates Antral Follicular Maturation and Survival via Thecal Paracrine Signaling in Cattle

LH supplementation in assisted reproductive technology cycles improves the ongoing pregnancy rate in women with poor ovarian response (POR). However, our knowledge of the precise role of LH during the follicular phase of the menstrual cycle is incomplete. To explore the role of LH in the maturation of small antral follicles, we used an in vitro two-cell system that involved coculturing bovine granulosa cells (GCs) and theca cells (TCs) on a collagen membrane. Treatment of TCs with LH stimulated androgen production in TCs by inducing the expression of androgenic factors, subsequently increasing estrogen biosynthesis in GCs by providing androgen substrates, and inducing aromatase expression. LH stimulation of TCs induced functional LH receptor expression in GCs, a response modulated by the synthesis and action of estrogen. In the presence of TCs, LH stimulation of TCs and FSH stimulation of GCs increased the expression of IGF-1, IGF-2, and IGF-1 receptor in GCs. LH-induced expression of thecal IGF-1 protected GCs from apoptosis and promoted GC survival. Furthermore, LH stimulation of TCs increased FSH sensitivity in GCs. Thus, the LH-TC axis may be involved in the acquisition of LH dependence and the survival of small antral follicles by upregulating androgen/estrogen biosynthesis and activating the IGF system. The use of LH supplementation in ovarian stimulation may increase gonadotropin sensitivity in small antral follicles and promote follicular growth and survival by suppressing GC apoptosis and follicular atresia, resulting in multiple follicular development, even in patients with POR.

Fenoxycarb exposure disrupted the reproductive success of the amphipod Gammarus fossarum with limited effects on the lipid profile

Insect growth regulator insecticides mimic the action of hormones on the growth and development of insect pests. However, they can affect the development of non-target arthropods. In the present study, we tested the effects of the growth regulator insecticide fenoxycarb on several endpoints in the freshwater crustacean Gammarus fossarum (Amphipoda). Females carrying embryos in their open brood pouch were exposed to 50 μg L^-1 fenoxycarb throughout the entire oogenesis (i.e. 21 days). After exposure, newborn individuals from exposed embryos were removed from the maternal open brood pouch for lipidomic analysis, while males were added to assess the reproductive success. After fertilization, the lipid profile, energy reserve content (lipids, proteins and glycogen), and activity of phenoloxidase − an enzyme involved in the immune response − were measured in females. No significant effect of fenoxycarb exposure was observed on the lipid profile of both newborn individuals and females, while reproductive success was severely impaired in exposed females. Particularly, precopulatory behavior was significantly reduced and fertilized eggs were unviable. This study highlighted the deleterious effects of the insect growth regulator fenoxycarb on gammarid reproduction, which could have severe repercussions on population dynamics.

Sodium fluoride disturbs DNA methylation of NNAT and declines oocyte quality by impairing glucose transport in porcine oocytes

Sodium fluoride (NaF) is used as a medicine to prevent tooth decay; however, excessive NaF could cause a pathological damage to the health. Recent studies showed that NaF impaired mouse oocyte maturation, included of abnormal spindle configuration, actin cap formation, cortical granule-free domain formation, and the following development after fertilization. However, few studies used large animals as models to study the toxicology of NaF on oocytes maturation. We proposed a hypothesis that NaF would affect the nuclear and cytoplasmic maturation of porcine oocytes and DNA methylation pattern of imprinted genes in oocytes. Our results showed that NaF affected cumulus expansion, polar body emission, spindle morphology, cortical granule distribution, early apoptosis, and the following development after parthenogenetic activation during porcine oocyte maturation. Moreover, NaF increased the DNA methylation of NNAT and decreased its expression, which disturbed the glucose transport in oocytes. These results suggest that NaF impairs the porcine oocytes maturation epigenetically, which provides a new toxicological mechanism of NaF on the oocyte maturation. Environ. Mol. Mutagen. 59:223-233, 2018. © 2017 Wiley Periodicals, Inc.

Production of blastocysts following in vitro maturation and fertilization of dromedary camel oocytes vitrified at the germinal vesicle stage

Cryopreservation of oocytes would serve as an alternative to overcome the limited availability of dromedary camel oocytes and facilitate improvements in IVP techniques in this species. Our goal was to develop a protocol for the vitrification of camel oocytes at the germinal vesicle (GV) stage using different cryoprotectant combinations: 20% EG and 20% DMSO (VS1), 25% EG plus 25% DMSO (VS2) or 25% EG and 25% glycerol (VS3) and various cryo-carriers; straws or open pulled-straw (OPS) or solid surface vitrification (SSV); and Cryotop. Viable oocytes were cultured in vitro for 30 h. Matured oocytes were fertilized with epididymal spermatozoa and then cultured in vitro in modified KSOMaa medium for 7 days. Survival and nuclear maturation rates were significantly lower (P ≤ 0.05) in oocytes exposed to VS3 (44.8% and 34.0%, respectively) than those exposed to VS1 (68.2% and 48.0%, respectively) and VS2 (79.3% and 56.9%, respectively). Although recovery rates were significantly lower (P ≤ 0.05) in SSV and Cryotop vitrified oocytes (66.9% to 71.1%) than those vitrified by straws with VS1 or VS2 solutions (86.3% to 91.0%), survival rates were higher in the SSV and Cryotop groups (90.7% to 94.8%) than in the straw and OPS groups (68.2% to 86.5%). Among vitrified groups, maturation and fertilization rates were the highest in the Cryotop-VS2 group (51.8% and 39.2%, respectively). These values were comparable to those seen in the controls (59.2% and 44.6%, respectively). Cleavage (22.5% to 27.9%), morula (13.2% to 14.5%), and blastocyst (6.4% to 8.5%) rates were significantly higher (P ≤ 0.05) in SSV and Cryotop groups than in straws. No significant differences were observed in these parameters between the Cryotop and control groups. We report for the first time that dromedary oocytes vitrified at the GV-stage have the ability to be matured, fertilized and subsequently develop in vitro to produce blastocysts at frequencies comparable to those obtained using fresh oocytes.

Melatonin improves the meiotic maturation of porcine oocytes by reducing endoplasmic reticulum stress during in vitro maturation

Under endoplasmic reticulum (ER)-stress conditions, the unfolded protein response (UPR) generates a defense mechanism in mammalian cells. The regulation of UPR signaling is important in oocyte maturation, embryo development, and female reproduction of pigs. Recent studies have shown that melatonin plays an important role as an antioxidant to improve pig oocyte maturation. However, there is no report on the role of melatonin in the regulation of UPR signaling and ER-stress during in vitro maturation (IVM) of porcine oocytes. Therefore, the objective of this study was to investigate the antioxidative effects of melatonin on porcine oocyte maturation through the regulation of ER-stress and UPR signaling. We investigated the changes in the mRNA/protein expression levels of three UPR signal genes (Bip/Grp78, ATF4, P90/50ATF6, sXbp1, and CHOP) on oocytes, cumulus cells, and cumulus-oocyte complexes (COCs) during IVM (metaphase I; 22 hours and metaphase II; 44 hours) by Western blot and reverse transcription-polymerase chain reaction analysis. Treatment with the ER-stress inducer, tunicamycin (Tm), significantly increased expression of UPR markers. Additionally, cumulus cell expansion and meiotic maturation of oocytes were reduced in COCs of Tm-treated groups (1, 5, and 10 μg/mL). We confirmed the reducing effects of melatonin (0.1 μmol/L) on ER-stress after pretreatment with Tm (5 μg/mL; 22 hours) in maturing COCs. Addition of melatonin (0.1 μmol/L) to Tm-pretreated COCs recovered meiotic maturation rates and expression of most UPR markers. In conclusion, we confirmed a role for melatonin in the modulation of UPR signal pathways and reducing ER-stress during IVM of porcine oocytes.

Unexpected repeat immature oocyte response after IVF stimulation: a case report

The purpose of ovarian stimulation in IVF is to recover mature oocytes at metaphase II stage which are capable of fertilization either when mixed with sperm or after ICSI. However, there have been instances when even after controlled ovarian stimulation (COS) and correct administration of human chorionic gonadotrophin (hCG) trigger for final oocyte maturation, the oocytes were found to be arrested at germinal vesicle (GV) or metaphase I (MI) stage. Similar dilemma is faced in cases of empty follicle syndrome (either genuine or due to inadequate response), however, in this condition, there is no retrieval of oocytes despite presence of mature looking follicles. We present an interesting case where despite presence of normally growing follicles and documentation of correct response to trigger and rise in estradiol levels, two subsequent IVF cycles; one triggered with recombinant hCG and second with GnRH agonist, hCG failed to yield mature oocytes. Both cycles yielded expected number of oocytes but all at immature MI stage even after dual trigger.

Characterization of a suboptimal IVF population and clinical outcome after two IVF cycles

The number of oocytes retrieved in in vitro fertilization (IVF) cycles is an independent factor influencing pregnancy rate (PR), and optimal number of oocytes would be between 10 and 15. This has led to the hypothesis that the identification of a suboptimal group of responders beforehand (4-9 oocytes retrieved) would allow physicians to optimize their PR. A retrospective observational study counting on 735 women doing an IVF treatment in our center was performed. Multivariable logistic regression was used to analyze the relationship between anti-Mullerian hormone (AMH) and antral follicle count (AFC), within suboptimal and optimal responders. We also analyzed the outcome of those patients with an estimated high probability of having an optimal response and the second cycles of those who did not get pregnant in the first cycle to observe the main significant traits that made them change from one group of responders to the other. Main results are that suboptimal responders account for almost half of our patients. Ovarian reserve markers (AMH and AFC) are significantly different in optimal and suboptimal responders, even when adjusted by age. There is a significant difference in the cumulative PR between both groups. Interestingly, 18.9% shifted from suboptimal to optimal response, and 36.9% from optimal to suboptimal.

Ovarian stimulation under the effect of isotretinoin

Isotretinoin (13-cis-retinoic acid) is a pharmaceutical vitamin A analog that is frequently used in the treatment of severe cystic acne, many women at reproductive age being exposed to this substance. This drug has a clearly documented teratogenicity and data from rodents and humans indicate that a direct aggression to ovarian follicles also occurs. Here we report the case of a 29-year-old woman with breast cancer referred for emergency preservation of reproductive potential that used isotretinoin up to the day before the initiation of ovarian stimulation. Ultrasound scan showed an antral follicle count of 17 and 13 follicles on the right and the left ovary, respectively, and her antimüllerian hormone levels were 4.03 ng/ml. Standard ovarian stimulation for oocyte vitrification in oncological patients was initiated during the luteal phase and final estradiol levels were 49 pg/ml. Three mature oocytes were obtained. Other four oocytes were retrieved in the germinal vesicle and metaphase I developmental stage, all of which matured in vitro in the following 30 h and were also vitrified. Response to ovarian stimulation, both in terms of the number of mature oocytes obtained and serum sex steroids production were in the lower range of what is observed in patients with a similar clinical profile. These findings suggest that isotretinoin impairs follicular-oocyte maturation.

Subchronic exposure to kalach 360 SL-induced endocrine disruption and ovary damage in female rats

Kalach 360 SL (KL), glyphosate (G) surfactant-based herbicides, is a systemic herbicide effective against weeds. It was applied in agriculture in Tunisia and throughout the world, which can represent a risk to non-target organisms. The aim of this study was to investigate the morphological and biochemical aspects of ovary injury after exposure to KL. Female Wistar rats were divided into three groups: group 1 was used as a control; group 2 orally received 0.07 ml of KL, (126 mg of G/kg) and group 3 orally received 0.175 ml of KL (315 mg of G/kg) each day for 60 days. The subchronic exposure of KL induces impaired folliculogenesis, ovary development, decreased oestrogen secretion, promoted oxidative stress and impairments of ovary histological aspects. Histological finding shows necrosis cell, vacuolisation of follicles, dissociated oocytes and granulosa cell, associated with several atretic follicles. We conclude that KL induces endocrine disruption and ovary damage in female rats.

Azadirachtin effects on mating success, gametic abnormalities and progeny survival in Drosophila melanogaster (Diptera)

BACKGROUND

Azadirachtin is a prominent natural pesticide and represents an alternative to conventional insecticides. It has been successfully used against insect pests. However, its effects on reproduction require further analysis. Here we investigated lethal and sublethal effects of azadirachtin, on treated adults in a model insect, Drosophila melanogaster (Meigen). Dose-mortality relationships as well as several parameters of reproduction (mating, spermatogenesis, oogenesis and fertility) were examined.

RESULTS

Neem-Azal, a commercial formulation of azadirachtin, applied topically on newly emerged adults, increased mortality with a positive dose-dependent relationship. The LD₅₀ (0.63 μg) was determined 24 h after treatment using a non-linear regression. Adults surviving this dose had a mating success that was divided by 3 and a progeny production reduced by half when males were treated, and even more when females were treated. When combining probability of survival, of mating and reduced progeny, it appeared that LD₅₀ induced a 98% reduction in reproductive rates. Reduced progeny was partially explained by the effect of adult treatment on gametes number and abnormalities. The number of cysts and the apical nuclei positions within the cysts decreased by 29.7% and 20%, respectively, in males. In females, the number of oocytes per ovary and the volume of basal oocytes also decreased by 16.1% and 32.4%, respectively.

CONCLUSION

Azadirachtin causes significant toxic effects in both sexes and decreases the fecundity and fertility of D. melanogaster. Females are more sensitive to azadirachtin. © 2017 Society of Chemical Industry.

Exposure effects of levonorgestrel on oogenesis in the fathead minnow (Pimephales promelas)

The synthetic progestin levonorgestrel is commonly utilized in human oral contraceptives. It enters the environment as a component of wastewater treatment plant effluent, and has been measured at low ng/L concentrations in surface waters. It has been shown to activate fish androgen receptors, causing the physical masculinization of females, changes in reproductive behavior, and decreases in fecundity. In the present study, the effects of levonorgestrel exposure on early-stage oogenesis in the fathead minnow (Pimephales promelas) was examined. Adult females were exposed to 0, 10, or 100 ng/L levonorgestrel for 14 d using a flow-through exposure system. The ovaries from each female were then removed via dissection and weighed for gonadosomatic index (GSI) calculations, and oocytes from one lobe preserved in Serra's fixative. Total numbers of late-stage vitellogenic oocytes exhibiting a germinal vesicle were then quantified. In a second exposure, blood plasma samples were collected from adult females and analyzed for vitellogenin concentrations using enzyme-linked immunosorbent assay. Females exposed to both concentrations of levonorgestrel developed male secondary sexual characteristics in a dose-dependent manner, and ovaries contained significantly fewer late stage oocytes. Exposure to 100 ng/L of levonorgestrel resulted in decreased GSI and blood plasma vitellogenin concentrations. The results suggest that female exposure to levonorgestrel alone may have profound effects on reproduction in progestin-contaminated environments. Environ Toxicol Chem 2017;36:3299-3304. © 2017 SETAC.

Fluoride-induced oxidative stress and apoptosis are involved in the reducing of oocytes development potential in mice

The present study was conducted to investigate the mechanisms of excessive-fluoride-induced reduction of oocyte development potential in mice. The development morphology of oocyte and the changes of pathomorphology in ovary were observed. The protein expression levels of apoptosis factors, including Bax, Bcl-2, casepase-3, casepase-9 and cytochrome c, and the mRNA expression levels of antioxidant enzymes, including SOD1, GSH-Px1, CAT and inducible nitric oxide synthase were measured by Western blot and real-time PCR, respectively. DNA damage in the ovary was analysed by single cell gel electrophoresis and TUNEL staining. Results indicated that the structure and function of ovarian cells were seriously damaged, followed, the development potential of oocyte was reduced by excessive fluoride. The expression levels of apoptosis factors were up-regulated and antioxidant enzymes were significantly down-regulated. Meanwhile, the contents of ROS, MDA, NO and iNOS were significantly increased. Whereas, the activities of SOD1, GSH-Px1 and CAT was significantly decreased compared with the control group. Simultaneously, the results of DNA analysis indicated that the tail length and tailing ratio of ovarian cells were significantly increased in the fluoride group. In summary, the results provided compelling evidence that excessive fluoride intake can reduce the development potential of oocyte by inducing oxidative stress and apoptosis in the ovary of female mice.

In vivo induction of human chorionic gonadotropin by osmotic pump advances sexual maturation during pre-spawning phase in adult catfish

Gonadal maturation is a critical event wherein gonads, under the influence of several hormones and factors, undergo cyclic morphological and physiological changes to produce functional gametes during the spawning phase. However, artificial induction can be effectively used to advance the maturation of gonad vis-à-vis spawning like behavior in seasonal breeders during the off-breeding season. In the present study, osmotic pumps loaded with 5000IU of human chorionic gonadotropin (hCG) or saline as control were implanted intraperitoneally for 21days during the pre-spawning phase (May-June) in catfish Clarias batrachus and C. gariepinus. Significant increase in gonado-somatic index and sperm motility, and in the levels of certain sex steroids were observed in the hCG treated catfish when compared to control while estradiol-17β (E₂) was low. Histological analysis in hCG treated testis revealed densely packed sperm and/or spermatids inside the lumen wherein the control testis displayed normal characteristics of the pre-spawning phase. In females, histological analysis showed a significant increase in post-vitellogenic full-grown immature follicles as seen in the spawning phase. In accordance with this, the steroid hormone profile correlated well with steroidogenic shift from E₂ to 17α,20β-DP indicating oocyte maturation. However, in the control ovaries of C. batrachus, perinucleolar and pre-vitellogenic oocytes were seen to be predominant. In addition, when compared with the control, the hCG treated group displayed a significant increase in the transcripts of several genes associated with gonadal growth. Taken together, artificial induction by slow release of hCG is an effective strategy to advance sexual maturation in catfish in a programmed manner.

Teratogenic Effects of Topiramate in a Zebrafish Model

Topiramate is commonly used for treating epilepsy in both children and adults. Recent clinical data suggests that administration of topiramate to women during pregnancy increases the risk of oral clefts in their offspring. To better understand the potential effects of topiramate, we dosed adult female zebrafish with topiramate, and investigated the altered morphologies in adult females and their offspring. It showed that topiramate-treated female fish had reduced oocyte maturation, and the survival rates of their offspring were seriously decreased during embryogenesis. In addition, around 23% of offspring displayed cartilage malformation in the craniofacial area, such as loss of ceratobranchial cartilages as well as impaired ceratohyal, Meckel’s cartilage and ethmoid plate development. Moreover, mineralization of ceratohyal, Meckel’s cartilage, and vertebrae were downregulated during bone development. Taken together, we concluded that topiramate impaired oogenesis in the maternal reproductive system, and then caused offspring cartilage malformation or bone dysplasia.

Kisspeptin as a promising oocyte maturation trigger for in vitro fertilisation in humans

The aim of this review is to analyse the effectiveness of exogenous kisspeptin administration as a novel alternative of triggering oocyte maturation, instead of currently used triggers such as human chorionic gonadotropin (hCG) or gonadotropin releasing hormone (GnRH) agonist, in women undergoing in vitro fertilisation (IVF) treatment. Kisspeptin has been considered a master regulator of two modes of GnRH and hence gonadotropin secretion, pulses and surges. Administration of kisspeptin-10 and kisspeptin-54 induces the luteinising hormone (LH) surge required for egg maturation and ovulation in animal investigations and LH release during the preovulatory phase of the menstrual cycle and hypothalamic amenorrhoea in humans. Exogenous kisspeptin-54 has been successfully administered as a promising method of triggering oocyte maturation, following ovarian stimulation with gonadotropins and GnRH antagonists in women undergoing IVF, due to its efficacy considering achieved pregnancy rates compared to hCG and GnRH agonists. Also, its safety in patients at high risk of developing ovarian hyperstimulation syndrome is noteworthy. Nevertheless, further studies would be desirable to establish the optimal trigger of egg maturation and to improve the reproductive outcome for women undergoing IVF treatment.

Oxidative stress as a damage mechanism in porcine cumulus-oocyte complexes exposed to malathion during in vitro maturation

Malathion is one of the most commonly used insecticides. Recent findings have demonstrated that it induces oxidative stress in somatic cells, but there are not enough studies that have demonstrated this effect in germ cells. Malathion impairs porcine oocyte viability and maturation, but studies have not shown how oxidative stress damages maturation and which biochemical mechanisms are affected in this process in cumulus-oocyte complexes (COCs). The aims of the present study were to determine the amount of oxidative stress produced by malathion in porcine COCs matured in vitro, to define how biochemical mechanisms affect this process, and determine whether trolox can attenuate oxidative damage. Sublethal concentrations 0, 750, and 1000 µM were used to evaluate antioxidant enzyme expressions, reactive oxygen species (ROS production), protein oxidation, and lipid peroxidation, among other oxidation products. COCs viability and oocyte maturation decreased in a concentration-dependent manner. Malathion increased Cu, Zn superoxide dismutase (SOD1), glutathione-S-transferase (GST), and glucose 6 phosphate dehydrogenase (G6PD) protein level and decreased glutathione peroxidase (GSH-Px) and catalase (CAT) protein level. Species reactives of oxygen (ROS), protein oxidation and Thiobarbituric acid reactive substances (TBARS) levels increased in COCs exposed to the insecticide, but when COCs were pre-treated with the trolox (50 µM) 30 min before and during malathion exposure, these parameters decreased down to control levels. This study showed that malathion has a detrimental effect on COCs during in vitro maturation, inducing oxidative stress, while trolox attenuated malathion toxicity by decreasing oxidative damage.

Natriuretic peptides improve the developmental competence of in vitro cultured porcine oocytes

BACKGROUND

Natriuretic peptides (NPs), brain and C type NPs (BNP and CNP), were involved in the maintenance of porcine oocyte meiotic arrest. The present study investigated the effects of NPs on developmental competence of immature porcine oocytes with follicles of different sizes.

METHODS

Follicular fluid NP levels were examined by radioimmunoassay. The developmental competence of porcine oocytes was evaluated by cleavage and blastocyst developmental rates after in vitro fertilization (IVF) or parthenogenetic activation (PA) of cumulus oocyte complexes (COCs), which were recovered from follicle with different sizes. NP levels were examined and classified according to the cleavage potential after IVF with COCs released from these follicles.

RESULTS

The BNP and CNP concentrations were increased with follicular size in follicular fluid and sustained at the set ranges of 3.0 - 6.0 mm follicles compared to 6.1 - 8.0 mm follicles. The oocytes developed from 3.0 to 6.0 mm follicles demonstrated increased embryo cleavage and blastocyst ratios after IVF, with an increased follicle size (P < 0.05). Moreover, BNP and CNP significantly promoted the blastocyst developmental rates of 3.0 - 6.0 mm follicles, but could not improve the developmental competence of oocytes from 6.1 to 8.0 mm follicles due to low NP levels. The COCs from 3.0 to 4.0 mm follicles were pre-incubated in 100 ng/ml of BNP and CNP media for 20 h before regular in vitro maturation, which demonstrated 2 to 3 folds higher developmental competencies in both PA and IVF groups compared to respective controls (P < 0.01).

CONCLUSIONS

The effects of BNP and CNP supplementation in the pre-maturation culture media (PMC) on porcine developmental competence from COCs in follicles of different sizes were different and improved the developmental competence of porcine oocytes from small antral follicle in vitro.

Individual luteolysis pattern after GnRH-agonist trigger for final oocyte maturation

Final oocyte maturation using GnRH-agonist trigger in a GnRH-antagonist protocol is increasingly common, as ovarian hyperstimulation syndrome is almost completely avoided. However, this approach might lead to reduced pregnancy rates due to severe luteolysis. This proof of concept study evaluated the extend of luteolysis by measuring progesterone levels 48 hours after oocyte retrieval in 51 patients, who received GnRH-agonist trigger for final oocyte maturation in a GnRH-antagonist protocol due to the risk of ovarian hyperstimulation syndrome. It was shown, that luteolysis after GnRHa-trigger differs greatly among patients, with progesterone levels ranging from 13.0 ng/ml to ≥ 60.0 ng/ml, 48 hours after oocyte retrieval. Significant positive correlations could be demonstrated between progesterone levels and the number of ovarian stimulation and suppression days (p = 0.006 and p = 0.002 respectively), the total amount of medication used for ovarian suppression (p = 0.015), the level of progesterone on the day of final oocyte maturation (p = 0.008) and the number of retrieved oocytes (p = 0.019). Therefore it was concluded, that luteolysis after GnRH-agonist trigger is patient-specific and also luteal phase support requires individualization. Longer stimulation duration as well as a higher level of progesterone on the day of final oocyte maturation and more retrieved oocytes will result in higher levels of progesterone 48 hours after oocyte retrieval.

Serum substance P concentrations to predict oocyte maturation index and clinical pregnancy

AIM

The aim of this study was to assess the predictive value of serum substance P (SP) concentrations on oocyte maturation and clinical pregnancy.

METHODS

Ninety-three women with unexplained infertility underwent intracytoplasmic sperm injection (ICSI) cycles. Antagonist protocol was started for each participant and at the day of oocyte pick up, serum samples were obtained from each participant to assess SP concentrations, and these concentrations were utilized to predict mature/total oocyte ratio and clinical pregnancy.

RESULTS

SP concentration was a significant predictor for mature/total oocyte ratio > 0.75 and clinical pregnancy. In correlation analyses, maturation index was significantly correlated with FSH (r= -0.226, p = 0.03), estradiol (r = 0.239, p = 0.021), peak estradiol (r = 0.414, p < 0.001), and substance P (r = 0.796, p < 0.001). In multivariate analyses, number of immature (beta coefficient = -0.379, p < 0.001), mature oocyte (beta coefficient = 0.473, p < 0.001), SP concentration (beta coefficient = 0.723, p < 0.001) and maturation index (beta coefficient = -0.387, p = 0.003) were significantly associated with clinical pregnancy.

CONCLUSION

SP concentrations at the day of oocyte pick up may be used to predict clinical pregnancy and may be an indirect indicator for cycle outcome in assisted reproductive technology (ART).

The Adverse Effects of Triptolide on the Reproductive System of Caenorhabditis elegans: Oogenesis Impairment and Decreased Oocyte Quality

Previous studies have revealed that Triptolide damages female reproductive capacity, but the mechanism is unclear. In this study, we used Caenorhabditis elegans to investigate the effects of Triptolide on the germline and explore its possible mechanisms. Our data show that exposure for 4 h to 50 and 100 mg/L Triptolide reduced C. elegans fertility, led to depletion and inactivation of spermatids with the changes in the expression levels of related genes, and increased the number of unfertilized oocytes through damaging chromosomes and DNA damage repair mechanisms. After 24 and 48 h of the 4 h exposure to 50 and 100 mg/L Triptolide, we observed shrink in distal tip cells, an increase in the number of apoptotic cells, a decrease in the number of mitotic germ cells and oocytes in diakinesis stage, and chromatin aggregates in -1 oocytes. Moreover, expression patterns of the genes associated with mitotic germ cell proliferation, apoptosis, and oocyte quality were altered after Triptolide exposure. Therefore, Triptolide may damage fertility of nematodes by hampering the development of oocytes at different developmental stages. Alterations in the expression patterns of genes involved in oocyte development may explain the corresponding changes in oocyte development in nematodes exposed to Triptolide.

GnRH antagonist and letrozole co-treatment in diminished ovarian reserve patients: a proof-of-concept study

The current study aimed to investigate the effects of luteal gonadotropin-releasing hormone (GnRH) antagonist pretreatment on the outcomes of diminished ovarian reserve (DOR) patients who were treated using a FSH/letrozole/GnRH antagonist (FLA) protocol. Thus, patients who had luteal GnRH antagonist pretreatment (AFLA) prior to stimulation were compared to patients who had the FLA protocol, only. An electronic database was used to identify patients and stimulation characteristics. Women who had a total antral follicle count (AFC) of <7 were included in the analysis. A total of 45 cycles using luteal GnRH antagonist pretreatment in combination with a letrozole/GnRH antagonist (AFLA) protocol were compared to 76 cycles using a FLA protocol, only. The total gonadotropin dose, duration of stimulation, and peak estradiol levels were comparable between the groups (p>0.05). However, the AFLA group had significantly more metaphase-2 (MII) oocytes (p=0.009), a higher oocyte maturity rate (MII/total oocytes) (p=0.029), and a higher mature oocyte yield (MII/AFC) (p=0.020) with more cleaved embryos (p=0.036), and a significantly reduced number of canceled cycles (26.7% vs. 44.7%; p=0.048). The clinical pregnancy rate per cycle was 22.2% vs. 13.2% (p=0.195) in the AFLA and FLA groups, respectively. Interestingly, a subgroup analysis including ESHRE Bologna criteria poor responder patients showed that the luteal administration of GnRH antagonist resulted in better outcomes when compared with the FLA protocol alone. In conclusion, luteal GnRH antagonist pretreatment improves ovarian stimulation parameters and reproductive outcomes in poor ovarian reserve IVF patients.

In-vitro and in-vivo biological activity of recombinant yellowtail kingfish (Seriola lalandi) follicle stimulating hormone

Biologically active recombinant yellowtail kingfish follicle stimulating hormone (rytkFsh) was produced in yeast Pichia pastoris and its biological activity was demonstrated by both in-vitro and in-vivo bioassays. Incubation of ovarian and testicular fragments with the recombinant hormone stimulated E₂ and 11-KT secretion, respectively. In-vivo trial in immature female YTK resulted in a significant increase of plasma E₂ levels and development of oocytes. In males at the early stages of puberty, advancement of spermatogenesis was observed, however plasma 11-KT levels were reduced when administered with rytkFsh.

Endocrine and paracrine regulation of meiotic cell cycle progression in teleost oocytes: cAMP at the centre of complex intra-oocyte signalling events

Participation of major endocrine and/or local autocrine/paracrine factors and potential interplay between apparently disparate intra-oocyte signalling events during maintenance and withdrawal of meiotic prophase arrest has been an area of active research in recent years. Studies on oocyte maturation have contributed substantially in the discovery of some of the most important biochemical and cellular events like functional significance of novel membrane-associated steroid receptors, elucidation of maturation promoting factor (MPF), cytostatic factor (CSF) and other signalling cascades that entrain the cell cycle clock to hormonal stimuli. While follicular estrogen has largely been implicated in maintenance of prophase arrest, involvement of maturational steroid and membrane progestin receptor in resumption of meiotic G2-M1 transition in piscine oocytes has been shown earlier. Moreover, detection of ovarian IGF system, maturational gonadotropin stimulation of IGF ligands and potential synergism between maturational steroid and IGF1 in zebrafish oocytes are most recent advancements. Though endocrine/paracrine regulation of cyclic nucleotide-mediated signalling events in meiotic cell cycle progression is well established, involvement of PI3K/Akt signalling cascade has also been reported in fish, amphibian and mammalian oocytes. The major objective of this overview is to describe how fish oocytes maintain high cAMP/PKA activity and how steroid- and/or growth factor-mediated signalling cascade regulate this pathway for the withdrawal of meiotic arrest. Moreover, special emphasis is placed on some recent findings on interaction of PKA with some of the MPF-regulating components (e.g., synthesis of cyclin B or MEK/MAPK signalling cascade) for the maintenance of prophase arrest.

Zinc deficiency reduces fertility in C. elegans hermaphrodites and disrupts oogenesis and meiotic progression

Zinc is necessary for successful gametogenesis in mammals; however the role of zinc in the gonad function of non-mammalian species has not been investigated. The genetic tractability, short generation time, and hermaphroditic reproduction of the nematode C. elegans offer distinct advantages for the study of impaired gametogenesis as a result of zinc deficiency. However the phenotypic reproductive effects arising from zinc restriction have not been established in this model. We therefore examined the effect of zinc deficiency on C. elegans reproduction by exposing worms to the zinc chelator N,N,N',N'-tetrakis (2-pyridylmethyl)ethane-1,2-diamine (TPEN). Treatment began at the early larval stage and continued until reproductive senescence. TPEN treatment reduced the total number of progeny produced by C. elegans hermaphrodites compared with control subjects, with the largest difference in output observed 48h after larval stage 4. At this time-point, zinc deficient worms displayed fewer embryos in the uterus and disorganized oocyte development when observed under DIC microscopy. DAPI staining revealed impaired oogenesis and chromosome dynamics with an expanded region of pachytene stage oocytes extending into the proximal arm of the gonad. This phenotype was not seen in control or zinc-rescue subjects. This study demonstrates that reproduction in C. elegans is sensitive to environmental perturbations in zinc, indicating that this is a good model for future studies in zinc-mediated subfertility. Aberrant oocyte development and disruption of the pachytene-diplotene transition indicate that oogenesis in particular is affected by zinc deficiency in this model.

Expression of two insulin receptor subtypes, insra and insrb, in zebrafish (Danio rerio) ovary and involvement of insulin action in ovarian function

Present study reports differential expression of the two insulin receptor (IR) subtypes in zebrafish ovary at various stages of follicular growth and potential involvement of IR in insulin-induced oocyte maturation. The results showed that mRNA expression for IR subtypes, insra and insrb, exhibited higher levels in mid-vitellogenic (MV) and full-grown (FG) rather than pre-vitellogenic (PV) oocytes. Interestingly, compared to the levels in denuded oocytes, mRNAs for both insra and insrb were expressed at much higher level in the follicle layer harvested from FG oocytes. Immunoprecipitation using IRβ antibody could detect a protein band of desired size (∼95kDa) in FG oocyte lysates. Further, IRβ immunoreactivity was detected in ovarian tissue sections, especially at the follicle layer and oocyte membrane of MV and FG, but not PV stage oocytes. While hCG (10IU/ml) stimulation was without effect, priming with insulin (5μM) could promote oocyte maturation of MV oocytes in a manner sensitive to de novo protein and steroid biosynthesis. Compared to hCG, in insulin pre-incubated MV oocytes, stimulation with maturation inducing steroid (MIS), 17α,20β-dihydroxy-4-pregnen-3-one (DHP) elicited higher maturational response. Potential involvement of insulin-mediated action on acquisition of maturational competence and regulation of oocyte maturation was further manifested through up regulation of 20β-hydroxysteroid dehydrogenase (20β-hsd), MIS receptor (mPRα), insulin-like growth factor 3 (igf3) and IGF1 receptor (igf1rb), but not cyp19a expression in MV oocytes. Moreover, priming with anti-IRβ attenuated insulin action on meiotic G2-M1 transition indicating the specificity of insulin action and physiological relevance of IR in zebrafish ovary.

Ovarian follicle structure of Zebrafish (Danio rerio Hamilton) after poly(2-ethyl-2-oxazoline) exposure

Poly(2-oxazoline)s have been widely known for their biomedical applications. They mimic natural systems and are generally used as liposomes, drug and gene delivery modules and also as pseudopeptides. In this study, effects of different doses (10 and 50 mg/L) of poly(2-ethyl-2-oxazoline) on ovarian follicle ultrastructure of zebrafish were investigated with light and electron microscopy. After five days of administation, ovary tissues were disected and routine histological processes were done. Severe structural deformation at zona radiata, follicular epithelium and outer granulosa cell structure were observed. Edema at follicular epithelium, zona radiata and vitelline envelope stuructures were detected. Dose dependent increase in the number of immature oocytes were seen. Briefly, it was demonstrated that poly(2-ethyl-2-oxazoline) exposure affected oogenesis and caused apoptosis in zebrafish.

Effects of anti-androgens cyproterone acetate, linuron, vinclozolin, and p,p'-DDE on the reproductive organs of the copepod Acartia tonsa

The study was performed to detect the effects of anti-androgenic compounds on the reproduction. In this paper alterations observed in the marine calanoid copepod Acartia tonsa exposed to environmental concentrations of cyproterone acetate (CPA), linuron (LIN), vinclozolin (VIN), and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p'-DDE) for 21 days covering a full life cycle are described. Histological alterations were studied with a focus on reproductive organs, gonad and accessory sexual glands. Exposure to ≥1.2 µg L(-1) CPA caused degeneration of spermatocytes and deformation of the spermatophore in males. In a single male exposed to 33 µg L(-1) CPA, an ovotestis was observed. In CPA exposed females, enhancement of oogenesis, increase in apoptosis and a decrease in proliferation occurred. Exposure of males to ≥12 µg L(-1) LIN caused degenerative effects in spermatogonia, spermatocytes and spermatids, and at 4.7 µg L(-1) LIN, the spermatophore wall displayed an irregular formation. In LIN exposed females, no such structural alterations were found; however, the proliferation index was reduced at 29 µg L(-1) LIN. At an exposure concentration of ≥100 µg L(-1) VIN, distinct areas in male gonad were stimulated, whereas others displayed a disturbed spermatogenesis and a deformed spermatophore wall. In VIN exposed female A. tonsa, no effects were observed. Male A. tonsa exposed to p,p'-DDE displayed an impairment of spermatogenesis in all stages with increased degrees of apoptosis. In p,p'-DDE-exposed females, a statistical significant increase of the proliferation index and an intensification of oogenesis were observed at 0.0088 µg L(-1).

Exposure to Aroclor-1254 impairs spindle assembly during mouse oocyte maturation

Polychlorinated biphenyls (PCBs), as typical environmental estrogen disruptors, are a structurally-related group of halogenated aromatic hydrocarbons that are composed of 209 isomers and present as a mixture in the environment. PCBs congener with different numbers and positions of chlorine atoms substituted on the biphenyl moiety. Aroclor-1254 is a mixture of more than 60 PCB congeners. Previous studies have provided the evidence that PCBs have severe negative effects on reproductive functions, but the effects of PCBs on spindle assembly during mouse oocyte maturation in vitro have not been reported. In the present study, female ICR mouse immature oocytes were cultured in M2 medium with 1 and 10 μg mL^-1 Aroclor-1254 separately in vitro. The percentage of germinal vesicle breakdown (GVBD) and the first polar body extrusion were recorded. The results showed no significant difference in the percentage of GVBD or the first polar body extrusion between control oocytes and Aroclor-1254-treated oocytes. Further studies showed that the normal localization of γ-tubulin and Aurora-A kinase was interfered and α-tubulin assembling into spindle was affected when mouse oocytes were exposed to Aroclor-1254. The length of spindle from 10 μg mL^-1 Aroclor-1254-treated oocytes was longer than that from control oocytes, and the spindle area in the Aroclor-1254-treated groups were decreased. Furthermore, the percentage of DNA damage in cumulus cells revealed an increase after exposed to Aroclor-1254. These results will provide the important reference for the prevention of reproductive disorders caused by PCBs. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1652-1662, 2016.

Fluoride impairs oocyte maturation and subsequent embryonic development in mice

The damage caused by fluorosis is permanent, and has been recognized as a public health problem in a number of regions of the world. Although multiple studies provided evidence that sodium fluoride (NaF) elicits adverse effects on reproductive function, the effect of fluoride on female germ cell development is not well understood. Therefore, the present study aimed at evaluating the effect of fluoride treatments on in vivo maturation and developmental potential of mouse oocytes, in which female ICR mice were treated with a range of doses (0, 30, 60, and 150 mg/L) of NaF. After treatment, mice were superovulated to collect ovulated oocytes. The effects of NaF on oocyte quality, fertilization potential and early embryonic development were evaluated, as well as the underlying mechanisms were primarily investigated. The findings of this study showed that NaF treatment resulted in abnormal spindle configuration, actin cap formation, and cortical granule-free domain formation. Additionally, overexposure of mice to NaF notably reduced ATP production and mitochondrial membrane potential, further influencing in vitro fertilization and subsequent embryonic development. These results indicated that NaF treatment impairs the subsequent embryonic developmental potential of the oocytes. In conclusion, overexposure to fluoride in vivo was associated with a significant disruption of cytoskeletal dynamics and decreased oocyte quality, affecting the oocyte's subsequent fertilization and embryonic development. Results of this study provide a rationale for treating reproductive diseases such as infertility or miscarriage caused by environmental contaminants. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1486-1495, 2016.

Di(2-ethylhexyl)phthalate: Adverse effects on folliculogenesis that cannot be neglected

Primordial follicle formation and the subsequent transition of follicles through primary and secondary stages constitute crucial events of oogenesis. In particular, in mammals, defects in the processes that precede and accompany the formation of the primordial follicle pool can affect the size of this population significantly, while alterations in follicle activation, growth and maturation can result in premature depletion of the follicle reserve or cause follicle arrest at immature stages. Over the last decade, in vitro and in vivo approaches have been used to provide evidence that exposure to di(2-ethylhexyl)phthalate(DEHP), the most widely used plasticizer, has a deleterious effect on various stages of folliculogenesis in rodents. There is growing concern, supported by epidemiological and experimental data, that DEHP may have similar effects in women. This article reviews the evidence, with particular reference to our own findings, that DEHP may actually exert a variety of adverse effects on mammalian folliculogenesis from early to final stages of oogenesis, including altered development of the primordial germ cells, impaired fetal oocyte survival and meiotic progression, reduced oocyte nest breakdown, acceleration of primordial follicle activation, altered follicle steroidogenesis and increased follicle atresia. These effects can cause serious complications for reproductive and nonreproductive women's health. In addition, emerging data indicate that phthalates, including DEHP, may cause subtle epigenetic changes in germ cells that can be transmitted to subsequent generations, with potential negative effects on human health. Environ. Mol. Mutagen. 57:589-604, 2016. © 2016 Wiley Periodicals, Inc.

Effects of GSM-like radiofrequency irradiation during the oogenesis and spermiogenesis of Xenopus laevis

We aimed to evaluate the effect of GSM-like radiofrequency electromagnetic radiation (RF-EMR) on the oogenesis, and spermiogenesis of Xenopus laevis, and so the development of the embryos obtained from Normal Females+Normal Males (i.e. "N(F)+N(M)"); Normal Females+RF-exposed Males (i.e. "N(F)+RF(M)"); RF-exposed Female+Normal Male (i.e. "RF(F)+N(M)"); and RF-exposed Female+RF-exposed Male (i.e. "RF(F)+RF(M)". Various, assessments were performed to determine potential teratogenic effects and mortality, body growth and behavior on first generation embryos. After exposing adults frogs of both sexes to 900MHz RF-EMR (at 1.0W/kg) for 8h a day over a 5-week period, the embryos' specific energy absorption rate (SAR) was calculated. In our present study (control group; 2.2% abnormal, 0.0% dead); with the N(F)+RF(M) combination, the long-term exposure of adult males to GSM-like radiation at 900MHz (RF: 2W) for 5 week/8h/day resulted in normal, abnormal and dead embryo ratios of 88.3%, 3.3% and 8.3%, respectively (p<0.001). In the RF(F)+N(M) combination, long-term exposure (5 week/8h/day) of adult females led to normal, abnormal and dead embryo ratios of 76.7%, 11.7%, and 11.7%, respectively (p<0.001). And in the RF(F)+RF(M) combination, long-term exposure (5 week/8h/day) of both adult males and females led to normal, abnormal and dead embryo ratios of 73.3%, 11.7%, and 15%, respectively (p<0.001). With the exception RF(F)+RF(M) group (p<0.001), no significant changes were observed on body growth (lengths) in comparison to the control group. It was also observed that the offspring of female adult Xenopus exposed to RF-EMR during oogenesis exhibited a more aggressive behavior compared to the control group. Cell phones radiation can thus lead to detrimental effects in humans' male and female reproductive cells.

Cumulus Cell Mitochondrial Resistance to Stress In Vitro Predicts Oocyte Development During Assisted Reproduction

CONTEXT

Complex cumulus cell-oocyte interactions govern energy utilization during oocyte development.

OBJECTIVE

This study investigates the relationship of cumulus cell mitochondria with oocyte development during ovarian stimulation for in vitro fertilization (IVF).

DESIGN

This is a prospective cohort study.

SETTING

The setting was an academic center.

PATIENTS

Thirty women underwent ovarian stimulation for IVF.

INTERVENTION(S)

Pooled cumulus cells were collected; numbers of total and mature oocytes and two-pronuclear (day 1), six- to eight-cell cleavage (day 3), and blastocyst (day 5) embryos were recorded.

MAIN OUTCOME MEASURE(S)

A mitochondrial bioassay was developed with Jurkat cells and used with cumulus cells from IVF patients to correlate mitochondrial membrane potential resistance to carbonyl cyanide 3-chlorophenylhydrazone (CCCP) stress with oocyte development and embryogenesis.

RESULTS

Adjusting for FSH administered and maternal age, cumulus cell mitochondrial membrane potential resistance to CCCP positively correlated with numbers of total (P < .025) and mature (P < .025) oocytes retrieved. The highest oocyte numbers that correlated with cumulus cell mitochondrial membrane potential occurred in women with the greatest ovarian response to FSH (mitochondrial membrane potential resistance to CCCP-log FSH interactions: total oocytes P < .025; mature oocytes P < .05). Multiple regression modeling of mature oocyte numbers, age, and cumulus cell mitochondrial membrane potential resistance to CCCP showed that numbers of mature oocytes best correlated with numbers of embryos at all stages (P < .0001).

CONCLUSION

During ovarian stimulation for IVF, cumulus cell mitochondrial membrane potential resistance to stress correlates with numbers of total and mature oocytes retrieved, suggesting that cumulus cell-oocyte interactions involving energy facilitate oocyte development.

The adverse outcome pathway (AOP) for chemical binding to tubulin in oocytes leading to aneuploid offspring

The Organisation for Economic Co-operation and Development (OECD) has launched the Adverse Outcome Pathway (AOP) Programme to advance knowledge of pathways of toxicity and improve the use of mechanistic information in risk assessment. An AOP links a molecular initiating event (MIE) to an adverse outcome (AO) through intermediate key events (KE). Here, we present the scientific evidence in support of an AOP whereby chemicals that bind to tubulin cause microtubule depolymerization resulting in spindle disorganization followed by altered chromosome alignment and segregation and the generation of aneuploidy in female germ cells, ultimately leading to aneuploidy in the offspring. Aneuploidy, an abnormal number of chromosomes that is not an exact multiple of the haploid number, is a well-known cause of human disease and represents a major cause of infertility, pregnancy failure, and serious genetic disorders in the offspring. Among chemicals that induce aneuploidy in female germ cells, a large majority impairs microtubule dynamics and spindle function. Colchicine, a prototypical chemical that binds to tubulin and causes microtubule depolymerization, is used here to illustrate the AOP. This AOP is specific to female germ cells exposed during the periovulation period. Although the majority of the data come from rodent studies, the available evidence suggests that the MIE and KEs are conserved across species and would occur in human oocytes. The development of AOPs related to mutagenicity in germ cells is expected to aid the identification of potential hazards to germ cell genomic integrity and support regulatory efforts to protect population health.