Reproductive Physiology Research Articles

Unraveling the Dynamics of Estrogen and Progesterone Signaling in the Endometrium: An Overview.

The endometrium is crucial for the perpetuation of human species. It is a complex and dynamic tissue lining the inner wall of the uterus, regulated throughout a woman's life based on estrogen and progesterone fluctuations. During each menstrual cycle, this multicellular tissue undergoes cyclical changes, including regeneration, differentiation in order to allow egg implantation and embryo development, or shedding of the functional layer in the absence of pregnancy. The biology of the endometrium relies on paracrine interactions between epithelial and stromal cells involving complex signaling pathways that are modulated by the variations of estrogen and progesterone levels across the menstrual cycle. Understanding the complexity of estrogen and progesterone receptor signaling will help elucidate the mechanisms underlying normal reproductive physiology and provide fundamental knowledge contributing to a better understanding of the consequences of hormonal imbalances on gynecological conditions and tumorigenesis. In this narrative review, we delve into the physiology of the endometrium, encompassing the complex signaling pathways of estrogen and progesterone.

What has embryo recovery and transfer taught us about equine reproductive physiology?

Equine embryo transfer has been the foundation stone on which modern reproductive technologies and novel research in this species has been built. Nonsurgical embryo recovery and transfer methods developed from the original surgical methods, and the ease with which these procedures can be undertaken has enabled these techniques to play a continuing role in original research. We document how embryo recovery and/or transfer have increased our knowledge about many of the events involved in equine reproductive physiology. These include, when the equine embryo enters the uterus, the importance and development of the blastocyst capsule, secretory products of early embryos, early maternal-embryo interactions, effects of uterine asynchrony on early embryo development, the role of endometrial cups and maternal immunological tolerance of extraspecies embryo transfers, and the influence of uterine environmental on fetal growth and development.

The Evaluation of Post-COVID-19 Effects on Ovarian Reserve and Menstruation in Reproductive-Aged Women in 2022: A Single-Centered Observational Study

Background: Despite the finite reproductive lifespan of women, the effect of Coronavirus disease 2019 (COVID-19) on female fertility is not widely evaluated, especially in the post-COVID recovery period. Objectives: The study aimed to detect COVID-19's long-term impact on ovarian reserve and menstruation in reproductive-aged women. Methods: One hundred and three reproductive-age women were recruited for this observational study from March to September 2022. Participants with a history of severe COVID-19 were included in the case group (n = 50), while those with non-severe or no infection were considered the control group (n = 53). The ovarian reserve was assessed using anti-Müllerian hormone (AMH) levels, and a structured questionnaire was used to evaluate menstrual cycle abnormalities. Results: We detected a significant decrease in the ovarian reserve indicator, AMH serum levels, in women with severe infection compared to controls (2.66 ± 1.95 vs. 3.38 ± 2.59 ng/L P = 0.03) in the post-COVID-19 recovery period. Characteristics related to menstrual cycle length and volume abnormalities, such as hypermenorrhea and hypomenorrhea, were similar in cases and controls (P = 0.79, P = 0.64), but the severity of dysmenorrhea was significantly higher in cases than controls (P = 0.02). Menstrual pain perception was not related to women’s marital status (r = 0.10, P = 0.27), employment (r = 0.16, P = 0.10), education (r = 0.11, P = 0.24), or AMH serum levels (r = 0.03, P = 0.74). Conclusions: This investigation sheds light on the potential long-term effects of severe COVID-19 on the ovarian reserve and menstrual cycle, which may lead to changes in female reproductive physiology. Longitudinal studies with larger sample sizes are needed to confirm the long-lasting fertility issues in women affected by severe COVID-19.

The concentrations and behavior of classic phthalates and emerging phthalate alternatives in different environmental matrices and their biological health risks.

Because of their excellent plasticity, phthalates or phthalic acid esters (PAEs) are widely used in plastic products. However, due to the recognized toxicity of PAEs and legislative requirements, the production and use of emerging PAE alternatives have rapidly grown, such as di-isononyl cyclohexane-1,2-dicarboxylate (DINCH) and di(2-ethylhexyl) terephthalate (DEHTP) which are the primary replacements for classic PAEs. Nowadays, PAEs and emerging PAE alternatives are frequently found in a variety of environmental media, including the atmosphere, sludge, rivers, and seawater/sediment. PAEs and emerging PAE alternatives are involved in endocrine-disrupting effects, and they affect the reproductive physiology of different species of fish and mammals. Therefore, their presence in the environment is of considerable concern due to their potential effects on ecosystem function and public health. Nevertheless, current research on the prevalence, destiny, and conduct of PAEs in the environment has primarily focused on classic PAEs, with little attention given to emerging PAE alternatives. The present article furnishes a synopsis of the physicochemical characteristics, occurrence, transport, fate, and adverse effects of both classic PAEs and emerging PAE alternatives on organisms in the ecosystem. Our analysis reveals that both classic PAEs and emerging PAE alternatives are widely distributed in all environmental media, with emerging PAE alternatives increasingly replacing classic PAEs. Various pathways can transform and degrade both classic PAEs and emerging PAE alternatives, and their own and related metabolites can have toxic effects on organisms. This research offers a more extensive comprehension of the health hazards associated with classic PAEs and emerging PAE alternatives.

Mitochondria of Porcine Oocytes Synthesize Melatonin, Which Improves Their In Vitro Maturation and Embryonic Development.

The in vitro maturation efficiency of porcine oocytes is relatively low, and this limits the production of in vitro porcine embryos. Since melatonin is involved in mammalian reproductive physiology, in this study, we have explored whether endogenously produced melatonin can help in porcine oocyte in vitro maturation. We have found, for the first time in the literature, that mitochondria are the major sites for melatonin biosynthesis in porcine oocytes. This mitochondrially originated melatonin reduces ROS production and increases the activity of the mitochondrial respiratory electron transport chain, mitochondrial biogenesis, mitochondrial membrane potential, and ATP production. Therefore, melatonin improves the quality of oocytes and their in vitro maturation. In contrast, the reduced melatonin level caused by siRNA to knockdown AANAT (siAANAT) is associated with the abnormal distribution of mitochondria, decreasing the ATP level of porcine oocytes and inhibiting their in vitro maturation. These abnormalities can be rescued by melatonin supplementation. In addition, we found that siAANAT switches the mitochondrial oxidative phosphorylation to glycolysis, a Warburg effect. This metabolic alteration can also be corrected by melatonin supplementation. All these activities of melatonin appear to be mediated by its membrane receptors since the non-selective melatonin receptor antagonist Luzindole can blunt the effects of melatonin. Taken together, the mitochondria of porcine oocytes can synthesize melatonin and improve the quality of oocyte maturation. These results provide an insight from a novel aspect to study oocyte maturation under in vitro conditions.

Crustacean endocrinology: Sexual differentiation and potential application for aquaculture

Crustaceans, which represent a significant subset of arthropods, are classified into three major classes: Ostracoda, Malacostraca, and Branchiopoda. Among them, sex manipulation in decapod species from the Malacostraca class has been extensively researched for aquaculture purposes and to study reproductive physiology and sexual plasticity. Some decapods exhibit sexual dimorphism that influences their biological and economic value. Monosex culture, in which only one sex is cultivated, increases production yields while reducing the risk of invasiveness, as genetic leakage into natural waters is less likely to occur. Differences in yield are also observed when cultivating different sexes, with all-male cultures of Macrobrachium rosenbergii being more profitable than both mixed and all-female cultures. Research on decapod sexual differentiation has led to a better understanding of sex determination and sexual differentiation processes in arthropods. Similar to most mammals and other vertebrate classes, Malacostraca crustaceans, including decapods, exhibit a cell-non-autonomous mode of sexual development. Genetic factors (e.g., sex chromosomes) and endocrine factors (e.g., insulin-like androgenic gland factor and crustacean female sex hormone) play pivotal roles in the development of sexually dimorphic traits. This review synthesizes the existing understanding of sex determination mechanisms and the role of sex hormones in decapod species. Additionally, it provides an overview of the methyl farnesoate, which has been suggested to be involved in male sex differentiation in some crab species, as well as the phenomenon of male-to-female sex reversal in host decapods caused by parasitic crustaceans.

O-115 Ovarian function in transmasculine people

Abstract Transgender and gender diverse patients are increasingly being seen in fertility clinics for fertility preservation and/or family building, yet very little is known about the effects of gender-affirming hormones on reproductive capacity, precluding data-driven counseling. Specific to transmasculine individuals, human studies reporting the effects of gender-affirming testosterone on ovarian function are all observational in nature, many with only short-term testosterone exposure. Animal studies contribute to our understanding of the effect of testosterone on reproductive physiology, but have yet to be confirmed in humans. This lecture will review what is and isn't known about reproductive outcomes after gender-affirming testosterone, including whether testosterone can be continued during ovarian stimulation, and make suggestions for improving the clinical experience for transmasculine individuals seeking fertility care. Areas for future study will also be discussed.

P-598 Novel inactivating homozygous mutation of the luteinizing hormone/choriogonadotropin receptor (LHCGR) and first live birth after in vitro maturation (IVM): a breakthrough

Abstract Study question How can pregnancy and live birth be achieved in patients with inactivating homozygous luteinizing hormone/choriogonadotropin receptor (LHCGR) mutation? Summary answer We report the first live birth after IVM in a patient with a novel homozygous inactivating LHCGR mutation (exon 6,c.470A>G). What is known already LH plays a fundamental role in female reproductive physiology and is responsible for steroidogenesis, oocyte maturation, ovulation and subsequent progesterone production by the corpus luteum. LH binds to the LHCGR located on the membrane of theca cells and mature granulosa cells. Inactivating mutations of the LHCG receptor lead to the impossibility to obtain final oocyte maturation both during natural cycles and after ovarian stimulation for in vitro fertilization purpose. Until now, egg donation represented the only option to treat their infertility. Study design, size, duration A case report. Participants/materials, setting, methods A 35 year-old nulliparous patient was referred to our university hospital for primary infertility. Main results and the role of chance The 35-year-old nulliparous patient presented with primary spaniomenorrhea but timely and spontaneous onset of secondary sexual characteristics. Serum LH levels were high (ranging from 15 to 30 IU/L) and to a lesser extent so were FSH levels. The ovarian reserve was normal for age, as assessed by serum AMH levels and ultrasound. There was no argument for polycystic ovarian syndrome, 21-hydroxylase deficiency, Cushing’s syndrome or hyperprolactinemia. Two previous attempts of controlled ovarian stimulation with gonadotropins and ovulation trigger with hCG and GnRH-agonist trigger had failed, resulting in low estradiol levels despite correct follicular growth on ultrasound and absence of ovulation after trigger. We identified by genetic analysis a novel homozygous inactivating LHCGR mutation (exon 6, c.470A>G) that had never been described previously. IVM was performed. A total of 7 oocytes were obtained after IVM, resulting in 4 Day 3 embryos. All embryos were frozen. Subsequently, 2 Day 3 embryos were replaced after endometrial preparation by hormone replacement therapy. The patient became pregnant and gave birth to a healthy baby. Two Day 3 embryos remain. Limitations, reasons for caution By definition, a case-report requires further studies to confirm our findings. Wider implications of the findings We describe a novel inactivating LHCGR mutation with subsequent live birth after IVM. As a growing number of gonadotropin receptor mutations are identified, this live birth successfully obtained places IVM as the only reliable option for these patients to conceive with their own eggs. Trial registration number not applicable

P-474 State-Trait Anxiety Inventory (STAI) punctuations as a non-invasive method for evaluating endometrial prognosis associated with cortisol and estradiol endometrial levels in IVF patients

Abstract Study question Are STAI State punctuations a potential non-invasive marker of endometrial prognosis in IVF patients? Summary answer Being stressed (determined by STAI State punctuations) is positively and negatively correlated with endometrial cortisol and estradiol levels, respectively, and highly associated with pregnancy consecution. What is known already Despite it is well known IVF treatments are a source of stress, this factor is frequently overlooked mainly due to the difficulty of stress evaluation and the lack of accurate biomarkers, not being standardized in the clinical setting. Steroid hormones are essential for reproductive physiology and highly related to well-known stress biomarkers such as cortisol. The lack of correlation between endometrial and serum steroid levels creates the need to look for non-invasive tools reflecting the endometrial microenvironment. In this study, by molecularly and psychologically characterizing patients, we aim to unveil non-invasive potential markers of stress associated to pregnancy consecution. Study design, size, duration This prospective cohort study included a total of 74 IVF patients (<45 years old, no uterine or systemic pathologies and good quality embryos) who underwent endometrial biopsy collection in mid-secretory phase for metabolites measurement between 2019 and 2023. These patients also underwent psychological evaluation by stress related questionnaires. Participants/materials, setting, methods The endometrial concentration of eleven steroid metabolites was measured by ultra-performance liquid chromatography-tandem mass spectrometry. Patients also underwent stress and anxiety evaluation (STAI), and reproductive outcomes in the first embryo transfer after biopsy collection were followed up. Wilcoxon and Barnard’s test were applied to compare the mean and proportion of stressed/unstressed, pregnant/not pregnant patients and metabolites levels. Correlations between metabolites’ levels and the proportion of stressed patients were evaluated by Pearson’s correlation coefficient. Main results and the role of chance Patients with STAI State punctuations > 60 presented higher mean endometrial cortisol levels (8.01 ng/g (n = 23) vs 5.08 ng/g (n = 35), p-value = 0.05) and lower mean estrone levels (54.97 ng/g (n = 23) vs 56.31 ng/g (n = 35), p-value = 0.049) than those patients with STAI State punctuations < 60. Also, in patients with high endometrial estradiol levels (>2 ng/g) a higher significant proportion of unstressed patients (STAI State < 60) was observed (88.9% vs 52% of unstressed patients in > 2 ng/g and < =2 ng/g estradiol concentrations, respectively) (n = 34, p-value = 0.036). As expected, a significant positive correlation between endometrial cortisol levels and stress (measured by STAI State questionnaire) (cor = 0.977, p-value = 0.023) and a negative correlation between endometrial estradiol levels and stress (cor = -0.9945, p-value = 0.0055) was evidenced. Additionally, a higher proportion of pregnant patients was observed when endometrial estradiol concentrations were high (>1 ng/g) (78.9% vs 50% pregnant in > 1 ng/g vs < =1 ng/g estradiol respectively, p-value = 0.035) and a higher proportion of not pregnant patients was observed when endometrial cortisol concentrations were high ( > =13.9 ng/g) (80% vs 34.4% not pregnant in > =13.9 ng/g and <13.9 ng/g cortisol respectively, p-value = 0.029). Limitations, reasons for caution Although we have employed validated psychological questionnaires and stress biomarkers, a causal relationship between stress and reproductive outcomes should be further explored. Wider implications of the findings This study demonstrated a significant correlation between stress and cortisol and estradiol levels. Since both metabolites’ levels were also related to pregnancy chances, STAI State psychological evaluation could be implemented in the clinical practice as a non-invasive method to prevent endometrial failure through psychological counseling. Trial registration number Not applicable

The consequences of heatwaves for the reproductive success and physiology of the wingless sub-Antarctic fly Anatalanta aptera

Sub-lethal effects of warming temperatures are an important, yet sometimes overlooked impact of climate change that may threaten the long-term survival of numerous species. This, like many other effects of climate change, is especially concerning for cold-adapted ectotherms living in rapidly warming polar regions. This study examines the effects of warmer temperatures on cold-adapted Diptera, using the long-lived sub-Antarctic sphaerocerid fly, Anatalanta aptera, as a focal species. We conducted two experiments to assess heat stress in adult flies, one varying the intensity of the heat stress (daily heating from 4 °C to 8 °C, 20 °C, or 24 °C) and one varying the frequency of heat stress exposure (heating from 4 °C to 12 °C every one, two, or three days) and examined consequences for reproductive success and metabolic responses. We found that more heat stress reduced reproductive output, but not timing of reproduction. Surprisingly, individuals sampled at different times during heat stress exposure were undifferentiable when all metabolite concentrations were analysed with redundancy analysis, however some individual metabolites did exhibit significant differences. Overall, our findings suggest that warmer temperatures in the sub-Antarctic may put this species at greater risk, especially when combined with other concurrent threats from biological invasions.

Development of Anti-inflammatory and Anti-oxidative Functional Foods and Their Role in Reproductive Physiology of Polycystic Ovarian Syndrome Induced Female Rats

Development of Anti-inflammatory and Anti-oxidative Functional Foods and Their Role in Reproductive Physiology of Polycystic Ovarian Syndrome Induced Female Rats

METTL14 mediates nerve growth factor-stimulated testosterone synthesis in porcine theca cells†.

Ovarian theca cells produce testosterone, which acts as a vital precursor substance for synthesizing estrogens during follicular development. Nerve growth factor (NGF) has been shown to participate in reproductive physiology, specifically to follicular development and ovulation. There is currently no available data on the impact of NGF on testosterone synthesis in porcine theca cells. Furthermore, m6A modification is the most common internal modification in eukaryotic mRNAs that are closely associated with female gametogenesis, follicle development, ovulation, and other related processes. It is also uncertain whether the three main enzymes associated with m6A, such as Writers, Erasers, and Readers, play a role in this process. The present study, with an in vitro culture model, investigated the effect of NGF on testosterone synthesis in porcine theca cells and the role of Writers-METTL14 in this process. It was found that NGF activates the PI3K/AKT signaling pathway through METTL14, which regulates testosterone synthesis in porcine theca cells. This study will help to further elucidate the mechanisms by which NGF regulates follicular development and provide new therapeutic targets for ovary-related diseases in female animals. Summary Sentence The present study investigated the effect of NGF on testosterone synthesis in porcine theca cells. It was found that NGF activates the PI3K/AKT signaling pathway through METTL14, which regulates testosterone synthesis in porcine theca cells.

Sperm handling and management in the teleost model fish Japanese medaka (Oryzias latipes)

Japanese medaka (Oryzias latipes) has been used as a model organism in different research fields, including reproductive physiology. Sperm motility is the most important marker for male fertility in fish and, thus, reproduction success. However, because of small volume of ejaculate and short motility duration, it is still challenging to manage the sperm collection and analysis in small model fish. In the present study, we aimed to investigate sperm motility and to optimize sperm collection, short-term sperm storage, and cryopreservation in Japanese medaka (Oryzias latipes). Using two different approaches for sperm collection: testes dissection and abdominal massage, different housing conditions and activating the sperm with different activation solutions, we investigated immediate sperm motility. In the second part of this study, we used different osmolalities of immobilization solution, Hank's Balanced Salt Solution (HBSS) for sperm storage at 0, 2 and 3 h after sperm collection. Finally, the sperm were cryopreserved using methanol as cryoprotectant and HBSS as extender at two different osmolalities, and post-thaw sperm motility was investigated. The highest post-activating sperm motility was achieved in the groups activated by the extender at 300 mOsm/kg. The quality of sperm remained unaffected by co-housing with females or with males only. Furthermore, Hanks’ Balanced Salt Solution (HBSS) with an osmolality of 600 mOsm/kg demonstrated its efficacy as a suitable extender for sperm storage, preserving motility and progressivity for 3 h. The highest post-thaw motility was around 35%. There were no significant differences between post-thaw motility in different groups. We also found that post-thaw incubation on ice can maintain the motility of the sperm for up to one hour after thawing.

The role of declining ataxia-telangiectasia-mutated (ATM) function in oocyte aging

Despite the advances in the understanding of reproductive physiology, the mechanisms underlying ovarian aging are still not deciphered. Recent research found an association between impaired ATM-mediated DNA double-strand break (DSB) repair mechanisms and oocyte aging. However, direct evidence connecting ATM-mediated pathway function decline and impaired oocyte quality is lacking. The objective of this study was to determine the role of ATM-mediated DNA DSB repair in the maintenance of oocyte quality in a mouse oocyte knockdown model. Gene interference, in vitro culture, parthenogenesis coupled with genotoxicity assay approaches, as well as molecular cytogenetic analyses based upon next-generation sequencing, were used to test the hypothesis that intact ATM function is critical in the maintenance of oocyte quality. We found that ATM knockdown impaired oocyte quality, resulting in poor embryo development. ATM knockdown significantly lowered or blocked the progression of meiosis in vitro, as well as retarding and reducing embryo cleavage after parthenogenesis. After ATM knockdown, all embryos were of poor quality, and none reached the blastocyst stage. ATM knockdown was also associated with an increased aneuploidy rate compared to controls. Finally, ATM knockdown increased the sensitivity of the oocytes to a genotoxic active metabolite of cyclophosphamide, with increased formation of DNA DSBs, reduced survival, and earlier apoptotic death compared to controls. These findings suggest a key role for ATM in maintaining oocyte quality and resistance to genotoxic stress, and that the previously observed age-induced decline in oocyte ATM function may be a prime factor contributing to oocyte aging.

Impact of seasonality on the reproductive physiology of diploid and tetraploid eastern oyster, Crassostrea virginica

Aquaculture production of triploid Eastern oyster, Crassostrea virginica, in the Gulf of Mexico (GoM) is reliant on naturally conditioned diploid females and tetraploid males. However, limited knowledge is available on their reproductive biology, including the gametogenic cycle. The aim was to quantify monthly changes in gametogenesis and gamete quality for triploid production in Eastern oyster in the GoM from June 2022 to July 2023. Monthly changes in temperature and salinity were recorded. Shell morphometrics and sex were determined. Sperm density, sperm activity, Spermatogenic Maturity Index (SMI), oocyte diameter, Oogenesis Maturity Index (OMI), and gonad coverage area were quantified. Mean monthly temperature ranged from 15.1 to 31.2 °C and salinity ranged from 12.5 to 27.6 PSU. Shell morphometrics increased over the annual cycle. When gametes were detectable, 48–80% of tetraploids and 45–70% of diploids were males. Hermaphrodites were identified in both ploidies in June; an additional tetraploid hermaphrodite was identified in March. Sperm density exhibited monthly fluctuations with high densities reported in June–July, September, and April–May. Sperm were motile when present, with high motility in June–July. High sperm velocity was also recorded in June–July and March–May. Tetraploids exhibited high SMI from June–September and April–May with increased variability in December–January. Mature sperm cells were predominant in tetraploids in June–July. Gonadal coverage was high from June–September and March–May. OMI was highest from June–September and March–May, while variability was high from August–March. Large oocyte diameters and gonad coverage areas were observed in June–July, September, and April–May. Together, these findings provide novel insights into reproductive dynamics for triploid production of Eastern oyster in GoM.

The Molecular Link between Obesity and the Endometrial Environment: A Starting Point for Female Infertility.

Female infertility constitutes a growing health problem in developing countries and could be associated with several possible causes including reproductive disorders, congenital malformations, infections and hormonal dysfunction. Nonetheless, a series of additional factors can also negatively impact female fertility and are represented by chronic exposure to environmental pollutants, stress, unhealthy lifestyle choices such as cigarette smoking and, among others, obesity. Excess weight is associated with several chronic diseases, and growing evidence demonstrates that it can compromise reproductive physiology due to its influence on endometrial gene expression and receptivity. Thus, the current review of the literature mainly focused on how obesity can impair uterine receptivity, mostly from a molecular point of view throughout the window of implantation (WOI) period at an endometrial level. It was also highlighted that an obesity-related increase in adipose tissue may lead to a modulation in the expression of multiple pathways, which could cause a hostile endometrial environment with a consequent negative impact on the uterine receptivity and the establishment of pregnancy. Thanks to the use of the endometrial receptivity assay (ERA), a specific microarray that studies the expression of a series of genes, it is now possible to evaluate the endometrial status of patients with infertility problems in a more detailed manner. Moreover, female fertility and endometrial receptivity could be affected by endometriosis, a chronic benign gynecological disease, whose cause-and-effect relationship to obesity is still uncertain. Therefore, further investigations would be required to better elucidate these mechanisms that govern embryo implantation and could be potentially useful for the generation of new strategies to overcome implantation failure and improve the pregnancy rates in obese women.

Effects of thyroxin and luteinizing hormone releasing hormone on reproductive physiology of Rohu (Labeo rohita): Insights into spawning performance, oocyte maturation, steroidogenesis, and follicular development genes

As the global aquaculture industry grows, attention is increasingly turning towards assisted reproductive technologies. In this study, we examined the impact of D-Ala6, Pro9-Net-mGnRH (LHRHa: 0.4 mL/kg) and two doses (1 and 10 μg/kg fish) of thyroxin (T4) administered through a single injection on oocyte maturation, spawning performance, sex steroid hormone levels, as well as the expression of genes related to steroidogenesis and follicle development (ZP2, Cyp19a1a and SF-1) in Rohu (Labeo rohita). The study found that untreated female Rohu did not spawn, while those treated with LHRHa and thyroxin ovulated and spawned across a hormonal gradient. The highest spawning success was observed with a thyroxin dosage of 10 µg/kg (no significant change with a dose of 1 μg/kg), and female latency period decreased with increasing dosage. Additionally, females treated with thyroxin exhibited significantly higher fecundity than other experimental groups. Treatment with LHRHa and two doses of thyroxin significantly increased the gonadal somatic index compared to the control and sham groups. Hormonal treatment also led to increased fertilization success, hatching rate, and larval survival. At 12 h post-injection, females treated with thyroxin exhibited a significant decline in estradiol levels and expression of Zp2, Cyp19a1a, and SF-1 compared to other experimental groups. Levels of DHP significantly increased across the hormonal gradient. Histological analyses supported a steroidogenic shift, where oocyte maturation was accelerated by hormone administration, particularly with both doses of thyroxin. In conclusion, the findings suggest that thyroxin is a recommended treatment for assisted reproduction of Rohu due to its ability to induce spawning, increase fecundity and improve larval survival.

Sirenian (manatees and dugongs) reproductive endocrinology

Reproductive hormones are essential to mating systems, behavior, fertility, gestation, parturition, and lactation in mammals and understanding the role of hormones in these processes is essential for species conservation. Sirenia is a unique order of marine mammals that include manatees, dugongs, and the extinct Steller’s sea cow. Extant Sirenian species are all listed as vulnerable due to habitat loss, cold stress, boat strike trauma, harmful algal bloom toxicity, entanglements, and illegal hunting. Therefore, successful reproduction is essential to maintaining and increasing Sirenian populations. Understanding Sirenian reproductive behavior, endocrinology, and mating strategies will aid conservation and management efforts to protect and provide the proper conditions for successful reproduction. The objectives of this review were to synthesize the current knowledge regarding reproductive cycles and endocrinology of Sirenians and identify knowledge gaps for future investigation. The current literature on Sirenian reproductive physiology reports reproductive seasonality, sexual maturation, estrous cyclicity and acyclicity, pregnancy, and sex differences. However, there remain significant knowledge gaps on the cyclicity and pulsatile release of gonadotropins, maturation in females, and characterization of pregnancy hormone profiles throughout gestation. To date, there is no explanation for confirmed pattern for ovarian acyclicity, nor understanding of the function of the numerous accessory corpus luteum described in manatees. Research including a greater number of longitudinal and postmortem studies on a wider variety of wild manatee populations are important first steps. Taken together, understanding the reproductive endocrinology of these vulnerable and threatened species is critical for policy and management decisions to better inform protection initiatives.

The Omics Revolution in Understanding Chicken Reproduction: A Comprehensive Review.

Omics approaches have significantly contributed to our understanding of several aspects of chicken reproduction. This review paper gives an overview of the use of omics technologies such as genomics, transcriptomics, proteomics, and metabolomics to elucidate the mechanisms of chicken reproduction. Genomics has transformed the study of chicken reproduction by allowing the examination of the full genetic makeup of chickens, resulting in the discovery of genes associated with reproductive features and disorders. Transcriptomics has provided insights into the gene expression patterns and regulatory mechanisms involved in reproductive processes, allowing for a better knowledge of developmental stages and hormone regulation. Furthermore, proteomics has made it easier to identify and quantify the proteins involved in reproductive physiology to better understand the molecular mechanisms driving fertility, embryonic development, and egg quality. Metabolomics has emerged as a useful technique for understanding the metabolic pathways and biomarkers linked to reproductive performance, providing vital insights for enhancing breeding tactics and reproductive health. The integration of omics data has resulted in the identification of critical molecular pathways and biomarkers linked with chicken reproductive features, providing the opportunity for targeted genetic selection and improved reproductive management approaches. Furthermore, omics technologies have helped to create biomarkers for fertility and embryonic viability, providing the poultry sector with tools for effective breeding and reproductive health management. Finally, omics technologies have greatly improved our understanding of chicken reproduction by revealing the molecular complexities that underpin reproductive processes.

Genome-Wide Identification, Expression and Response to Estrogen of Vitellogenin Gene Family in Sichuan Bream (Sinibrama taeniatus).

To enhance our understanding of teleost reproductive physiology, we identified six Sichuan bream (Sinibrama taeniatus) vitellogenin genes (vtg1-6) and characterized their sequence structures. We categorized them into type Ⅰ (vtg1,4,5 and 6), type Ⅱ (vtg2) and type Ⅲ (vtg3) based on differences in their subdomain structure. The promoter sequence of vtgs has multiple estrogen response elements, and their abundance appears to correlate with the responsiveness of vtg gene expression to estrogen. Gene expression analyses revealed that the vitellogenesis of Sichuan bream involves both heterosynthesis and autosynthesis pathways, with the dominant pathway originating from the liver. The drug treatment experiments revealed that 17β-estradiol (E2) tightly regulated the level of vtg mRNA in the liver. Feeding fish with a diet containing 100 μg/g E2 for three weeks significantly induced vtg gene expression and ovarian development, leading to an earlier onset of vitellogenesis. Additionally, it was observed that the initiation of vtg transcription required E2 binding to its receptor, a process primarily mediated by estrogen receptor alpha in Sichuan bream. The findings of this study provide novel insights into the molecular information of the vitellogenin gene family in teleosts, thereby contributing to the regulation of gonadal development in farmed fish.