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Yining Li, Yeu-Farn Lin, Xiang Zhou, Hugh J Clarke, and Daniel J Bernard

Ovarian follicle development is regulated by locally produced TGFβ superfamily members. The TGFβ type III receptor (TGFBR3, or betaglycan), which regulates the actions of diverse TGFβ ligands, including inhibins, is expressed in different ovarian cell types. However, its functional roles in the ovary have not been investigated in vivo. Here, we ablated Tgfbr3 in murine oocytes using the Cre-loxP system. Oocyte-specific Tgfbr3 knockout (cKO) females were fertile, producing litters of similar size and frequency as controls. Their ovarian weights and histology were also normal. Though we confirmed efficient recombination of the floxed alleles, we did not detect Tgfbr3 mRNA in purified oocytes from superovulated cKO or control mice. These results challenge earlier observations of betaglycan protein expression in this cell type. Regardless, Tgfbr3 in the murine oocyte is clearly dispensable for female fertility.

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Xiaolei Yao, M A EI-Samahy, Shenhua Xiao, Zhibo Wang, Fanxing Meng, Xiaodan Li, Yongjin Bao, Yanli Zhang, Ziyu Wang, Yixuan Fan, and Feng Wang

Being a novel target of luteinizing hormone (LH), the effect of CREB-binding protein/P300-interacting trans-activator with ED-rich tail member 4 (CITED4) gene on the proliferation, apoptosis, and steroidogenesis of ovarian granulosa cells (GCs) in Hu sheep was investigated. The presence of CITED4, CREB-binding protein (CBP), CCAAT/enhancer-binding protein alpha (C/EBPα) and -beta (C/EBPβ) proteins was demonstrated in GCs and luteal cells. CITED4 protein in GCs was induced by LH, and CITED4 overexpression moderately increased GC responses to LH. In contrast, CITED4 knockdown in GCs decreased prostaglandin (PGE2)-induced LH target gene levels. Moreover, PGE2-stimulated CITED4 mRNA expression was blocked by ERK1/2 inhibition (U0126), suggesting that CITED4 is a downstream target of the ERK1/2 pathway in sheep GCs. In contrast to CITED4 knockdown, CITED4 overexpression promoted GC proliferation, inhibited apoptosis, upregulated cell cycle-related genes, and downregulated apoptosis-related genes. Additionally, CITED4 overexpression induced cell cycle transition from S to G2/M phase. No effect was observed with CITED4 knockdown. CITED4 overexpression increased progesterone (P4) production levels and STAR mRNA expression, whereas CITED4 knockdown decreased P4 production and STAR and 3β-HSD mRNA expression levels. Thus, our results suggest that CITED4 is involved in regulating the expression of LH-induced genes and the ERK1/2 pathway and the proliferation, apoptosis, and steroidogenesis in Hu sheep GCs by modulating the expression of related genes. These findings will help understand the role of CITED4 in follicular development and ovulation of pre-ovulatory follicles.

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Behzad Hajizadeh Maleki and Bakhtyar Tartibian

The existing evidence suggests that the human reproductive system may be potentially vulnerable to COVID-19 infection. However, little is known about the virus–host interaction of COVID-19 in sperm cells. We are the first to address the connection between changes in multiple seminal biomarkers and reproductive function in male patients recovering from COVID-19. In a prospective longitudinal cohort study, seminal ACE2 activity, markers of inflammation and oxidative stress, apoptotic variables, and semen quality parameters were evaluated at 10-day intervals for a maximum follow-up time of 60 days among male patients with laboratory-confirmed COVID-19 (n = 84) and healthy controls (CON; n = 105). At the baseline and the subsequent follow-ups, the COVID-19 group revealed significantly higher levels of seminal plasma ACE2 enzymatic activity, IL-1β, IL-6, IL-8, IL-10, TGF-β, TNF-α, IFN-α, IFN-γ, ROS, caspase-8, caspase-9, and caspase-3 activity as well as lower levels of SOD activity than those in the CON group (P  < 0.05). These perturbations tended to persist over time and were correlated with significant impairments in semen volume, progressive motility, sperm morphology, sperm concentration, and the number of spermatozoa. We provide the direct experimental evidence that the male reproductive system could be targeted and damaged by the COVID-19 infection. These findings go beyond our current understanding of the disease, suggesting that the reproductive function of the patients recovering from the disease should be precisely followed and evaluated to detect and avoid more serious reproductive problems in the future, as they may develop a transient state of male subfertility like those with oligoasthenoteratozoospermia.

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Sinan Ozkavukcu, Nilay Kuscu, Dileyra Adiguzel, Guldane Cengiz-Seval, and Ciler Celik-Ozenci

Nilotinib is a second-generation tyrosine kinase inhibitor (TKI) that is widely used to treat patients with Philadelphia chromosome-positive chronic myeloid leukaemia (CML). TKIs provided a significant improvement in terms of survival rates and disease-free period in CML; however, there is insufficient knowledge about their side effects, including reproductive toxicity. Since nearly half of the CML patients are in their reproductive age, and newly announced indications cover the treatment of the paediatric age groups, concerns arise about the effects of these drugs on the reproductive system, as there are no controlled preclinical studies. We investigated acute and long-term gonadotoxic and teratogenic effects of nilotinib, utilising a mouse model that simulates various clinical scenarios. We observed significant testicular damage in mice receiving nilotinib according to Johnsen’s score analysis. Alterations were observed in female mice’s number of follicles, as the primordial follicle numbers significantly decreased. Proliferating cell number in both genders’ gonads decreased and apoptosis rate increased significantly. The nilotinib-received female and male mice’s pregnancy rates were low compared to controls. A significant decrease in the thickness of the spongiotrophoblast and decidual layers of the placenta was detected in pregnancies consisting of male and/or female mice treated with nilotinib. The results of this study establish a critical point of view for clinical translation and indicate the importance of consulting patients for directing them to fertility preservation and contraception options for both genders before nilotinib treatment.

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Ana Filipa Ferreira, Maria Soares, Sandra Almeida Reis, João Ramalho-Santos, Ana Paula Sousa, and Teresa Almeida-Santos

Mitochondrial supplementation was proposed as a complementary treatment to assisted reproductive technologies to improve oocyte competence and support post-fertilization development. This strategy is based on the fact that poor-quality/aged oocytes contain lower and dysfunctional mitochondria. However, the efficacy and safety of mitochondrial supplementation are still controversial. Therefore, this review summarizes the clinical/biological outcomes of mitochondrial supplementation, aiming to improve oocyte competence or explore the safety of this technique, and was based on an online search using PubMed and Web of Science, until September 2019. The studies included reported outcomes related to the efficacy and safety of mitochondrial supplementation either in human or animal models (bovine, porcine and mouse). Extracted data were organized according to study objective, the mitochondrial source and the main outcomes: fertilization/pregnancy rates, embryo development and adverse outcomes. Clinical pregnancy was not improved in the only randomized controlled trial published, although an increase was demonstrated in other non-randomized studies. Fertilization rate and embryo development were not different from control groups in the majority of studies, although performed in different contexts and using diverse sources of mitochondria. The safety of mitochondria transfer is still a concern, however, the euploid rate and the absence of reported congenital malformation from the clinical studies are reassuring. In summary, mitochondrial supplementation does not seem to cause harm although the benefit of improving oocyte competence is still unclear due to the diversity of methodological approaches and low-quality of the data available. Analyzed data support the need to investigate further, in both pre-clinical and clinical contexts.

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Jacqueline M Wallace, John S Milne, and Raymond P Aitken

The competition for nutrients when pregnancy coincides with continuing growth in biologically immature adolescent girls increases their risk of preterm delivery and low birthweight and is partly replicated in the overnourished adolescent sheep paradigm. Although overfeeding to promote rapid maternal growth robustly leads to a reduction in average birthweight relative to slow-growing control-fed adolescents of equivalent age, the extent of prenatal compromise is variable. This retrospective analysis of a large cohort of identically managed pregnancies determined whether maternal anthropometry predicts the severity of fetal growth-restriction (FGR) in growing adolescents. Singleton pregnancies were established by embryo transfer in adolescents subsequently control-fed (n = 96) or overnourished. The latter pregnancies were classified as non-FGR (n = 116) or FGR (n = 96) if lamb birthweight was above or below the optimally fed control mean minus 2SD. A similar approach categorised placental growth-restriction (PlGR) and preterm delivery. Gestation length, placental mass and lamb birthweight were FGR < non-FGR < control (post hoc P < 0.01). Relative to the non-FGR group, overnourished dams with FGR were marginally leaner and lighter at conception (P = 0.023/P = 0.014) and had greater gestational weight gain (GWG) during the first-third of pregnancy (P < 0.001). GWG during this early period was also higher in PlGR compared with non-PlGR, and in very preterm vs term deliveries (P < 0.01). Likewise maternal leptin concentrations (fat accrual biomarker) were FGR > non-FGR by day 60, and changes in leptin throughout pregnancy predicted attenuated fetal cotyledon mass and birthweight (P = 0.01 to <0.001). The anthropometric antecedents of FGR in still-growing adolescent sheep originate in early pregnancy coincident with early placental development.

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Heather Flanagan, Chih-Jen Lin, Lisa L Campbell, Paddy Horner, Andrew W Horne, and Norah Spears

Ectopic pregnancy (EP) is defined as the implantation of an embryo outside of the uterus and is a leading cause of first trimester maternal mortality and morbidity. This article discusses a possible role for epithelial to mesenchymal transition in the pathogenesis of EP, given the notable similarity of protein expression between the two processes.

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Natalie M Hohos, Emily M Elliott, Asma Giornazi, Elena Silva, John D Rice, and Malgorzata E Skaznik-Wikiel

High-fat diet (HFD) consumption in female rodents causes impaired estrous cyclicity, fewer pups per litter, and dysregulation of key ovulatory genes suggesting that HFD-induced subfertility may be due to ovulatory dysfunction. To test this hypothesis female mice were fed chow or HFD for 10 weeks at which point ovulation and ovarian gene expression of endothelin-2 (Edn2), a gene critical for ovulation, were assessed. After 10 weeks of HFD, both mice that remained lean and those that became obese had fewer ovulated oocytes than chow controls (P = 0.041, P = 0.0030, respectively). In chow controls, Edn2 was expressed as expected with basal levels during diestrus and proestrus, increased 11.6-fold during estrus, and decreased to basal levels during metestrus. In HFD mice, Edn2 was dysregulated across the entire estrous cycle as were other Edn2 system components (endothelin converting enzyme 1 (Ece-1), and the endothelin receptors (Ednra, Ednrb)). Interestingly, we found dysregulation of key ovarian steroidogenic genes after HFD. We also found that estradiol treatment in prepubertal mice increased Edn2 expression in the ovary (P = 0.030), suggesting that impaired steroidogenesis may be involved in the HFD-induced dysregulation of ovarian Edn2. In conclusion, HFD leads to ovulatory dysfunction regardless of the development of obesity, which appears to be mediated through dysregulation of ovarian Edn2 expression.

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Teruhito Ishihara, Oliver W Griffith, Gerard A Tarulli, and Marilyn B Renfree

Male germ cells undergo two consecutive processes – pre-spermatogenesis and spermatogenesis – to generate mature sperm. In eutherian mammals, epigenetic information such as DNA methylation is dynamically reprogrammed during pre-spermatogenesis, before and during mitotic arrest. In mice, by the time germ cells resume mitosis, the majority of DNA methylation is reprogrammed. The tammar wallaby has a similar pattern of germ cell global DNA methylation reprogramming to that of the mouse during early pre-spermatogenesis. However, early male germline development in the tammar or in any marsupial has not been described previously, so it is unknown whether this is a general feature regulating male germline development or a more recent phenomenon in mammalian evolutionary history. To answer this, we examined germ cell nuclear morphology and mitotic arrest during male germline development in the tammar wallaby (Macropus eugenii), a marsupial that diverged from mice and humans around 160 million years ago. Tammar pro-spermatogonia proliferated after birth and entered mitotic arrest after day 30 postpartum (pp). At this time, they began moving towards the periphery of the testis cords and their nuclear size increased. Germ cells increased in number after day 100 pp which is the time that DNA methylation is known to be re-established in the tammar. This is similar to the pattern observed in the mouse, suggesting that resumption of germ cell mitosis and the timing of DNA methylation reprogramming are correlated and conserved across mammals and over long evolutionary timescales.