Reproduction, Fertility and Development
Intracellular lipid is involved in long-term blastocyst competence to survive vitrification. We studied how protein removal affects bovine embryo development in vitro, lipid content and pregnancy outcomes, and found that calf weight at birth was altered depending on specific embryonic kinetics within vitrified–warmed embryos. Therefore, it is possible to modify calf phenotypes by introducing simple changes in culture conditions combined with selection of embryos.
Poly(A)-binding proteins function in the timely regulation of gene expression during oocyte maturation, fertilisation and early embryo development in vertebrates. In this review, we comprehensively evaluate and discuss the expression patterns and particular functions of the embryonic poly(A)-binding protein (EPAB) and poly(A)-binding protein, cytoplasmic 1 (PABPC1) genes, especially in mouse and human oocytes and early embryos.
It is still unspecified if and how the number of embryos or fetal sex affect pregnancy outcome. The present study determined whether there are differences in transcriptome profiles of the beaver placenta as a result of fetal sex or multiplicity of gestation. The results indicate that the number of fetuses affects the expression profile in the subplacental transcriptome. Enhancement of transcriptome resources will improve our understanding of the pathways relevant to proper placental development and successful reproduction in general.
Polydatin (PD) has antioxidant activity and is useful for embryo development in vitro. Supplementation of IVM medium with PD scavenged reactive oxygen species and improved embryo developmental competence via induction of sirtuin 1 (Sirt1).
Immune and renal function, both critical for reproductive success, were evaluated to determine if exposure of postreproductive female mice to young ovaries would influence these non-reproductive physiological functions. Postreproductive mice received new (60-day-old) ovaries at 12 months of age and were evaluated at 16 months of age. Age-related declines in immune and renal function in 16-month-old control mice were restored to levels found in 6-month-old mice by ovarian transplantation. Re-establishment of reproductive function in aged female mice positively influenced non-reproductive functions.
Honey bees, which are vital agricultural pollinators, are at risk from numerous factors. The ability to artificially inseminate these species provides a means to strengthen them genetically by collecting semen from bees of different regions throughout the world and then inseminating bees at distant locations. Our study aimed to substantially improve the viability of spermatozoa between collection and insemination.
The aim of this study was to compare the efficacy of paclitaxel (PT) and docetaxel (DT) in reducing spindle damage in bovine oocytes during vitrification. The important finding of the study was that pretreatment of bovine oocytes with 0.05 µM DT for 30 min before vitrification reduced spindle damage to a greater degree than pretreatment with 1.0 µM PT. This finding will be useful in improving oocyte cryopreservation in the future.
Limited information is available about the role of growth factors in very early embryonic development. This study demonstrates the presence of stem cell factor, stanniocalcin-1, connective tissue growth factor and heparin-binding epidermal growth factor-like growth factor in bovine uterine fluid, endometrium and embryos during blastocyst formation. The results suggest a role for these proteins in early embryo development in cattle.
Ovaries contain a large number of small follicles, but the meiotic and developmental competence of oocytes from these follicles is quite low. In the present study we demonstrated that the addition of 200 ng mL–1 vascular endothelial growth factor to the IVM medium increased the maturation rate of porcine oocytes from small follicles and that blastocyst formation following parthenogenetic activation also increased. These findings may contribute to efficient animal production and human assisted reproductive technology.
Improvements in the quality of stallion semen are required to increase the success of artificial insemination. The aim of this study was to assess the effects of the addition of docosahexaenoic acid to semen diluents on the quality of stallion semen. Docosahexaenoic acid increased spermatozoa motility and membrane fluidity in cooled semen and thus can be used to increase the quality of spermatozoa.
The present study investigated DNA methylation profiles and mRNA expression of imprinted and non-imprinted candidate genes in bovine oocytes from antral follicles of three different size classes (≤2 mm, 3–5 mm, ≥6 mm) to unravel the epigenetic contribution to follicular and oocyte growth. We observed an increased number of aberrantly methylated alleles in bH19, bSNRPN and bDNMT3 Lo of oocytes from small antral follicles and an increased frequency of CpG sites with an unclear methylation status for DNMT3 Ls in large follicles. Results indicate that a follicle diameter of ~2 mm is critical for establishing DNA methylation profiles.
Evidence exists that early life nutritional insults can predispose to metabolic disorders, like Type 2 diabetes, for which excessive hepatic glucose production is a contributing factor. Maternal undernutrition alters the epigenetic status of the glucocorticoid receptor and increases the expression of gluconeogenic enzymes in the liver of male offspring. Undernutrition in the womb programs long-lasting changes in specific gene expression that leads to persistent metabolic abnormalities.
Antifreeze glycoprotein 8 (AFGP8) supplementation during vitrification beneficially protects bovine blastocysts against chill-induced injury. AFGP8 supplementation during vitrification enhances the cryosurvival of bovine blastocysts. AFGP8 supplementation during vitrification improves the subsequent in vitro developmental capacity of bovine blastocysts.
Knowledge of molecular defects in spermatozoa becomes critical during assisted reproduction to treat male factor infertility. Herein we show that the absence or low expression of protocadherin 11Yb (PCDH11Yb) in spermatozoa is associated with male factor infertility. Profiling of a panel of differentially expressed sperm proteins, including PCDH11Yb, in men with infertility may be of diagnostic and therapeutic value in infertility management.
Metronidazole, an essential medicine, adversely affects male fertility. We aimed at investigating the capability of Rosmarinic acid to reverse metranidazole induced male infertility. We found that certain doses of Rosmarinic acid could reverse metronidazole’s effects on sperm count, motility, morphology and testis ultrastructure. Our findings have great clinical implications where Rosmarinic acid might have a potential use in reversing Metronidazole induced male infertility.
Live cell RNA imaging in mammalian embryos would represent a quantum leap in understanding cell differentiation and early embryonic development. Applicability of RNA imaging by SmartFlare technology was tested in equine embryos surrounded by an embryonic capsule and/or the zona pellucida, nude trophoblastic vesicles and fibroblast cell cultures. Encapsulated embryos block SmartFlare uptake, but stages surrounded by the zona pellucida only and nude vesicles incorporate the probes, leading to specific fluorescence suitable for tracing gene expression cascades necessary for further embryo development.
Maternal obesity leads to premature aging of male offspring reproductive capacity and increases testes oxidative stress in male rat offspring. Our results show that maternal obesity modifies the antioxidant enzyme system in the testes of offspring, which, in turn, affects testicular physiological functions and leads to premature aging of male reproductive capacity.
The mechanism underlying the non-genomic action of progesterone in sperm functions and related Ca2+ mobilisation remains elusive. Herein we report the expression of gamma-aminobutyric acid type A receptor delta subunit (GABRD) in human and rodent spermatozoa and its involvement in mediating the progesterone-induced acrosome reaction through its interaction with purinergic P2X2 receptors. GABRD represents a novel progesterone receptor or modulator in sperm responsible for the progesterone-induced Ca2+ influx required for the acrosome reaction.
The possibility of growing immature human ovarian follicles in laboratories will assist fertility restoration. The aim of the present study was to investigate whether growth of immature follicles can be promoted by using different culture surfaces and supplementation with a growth factor. It was unclear whether any of the culture surfaces had an advantage over the others. In addition, the growth factor did not promote growth. Further studies should test other culture surfaces and identify additional fluid supplements, so that an optimal system can be developed.
Mitochondrial ferritin is an iron-storage protein highly expressed in human and mouse spermatozoa. This work showed that male mice, but not female, in which mitochondrial ferritin was genetically deleted have reduced fertility without significant alterations in sperm parameters. These data show that mitochondrial ferritin has a role in male fertility.
A diabetic pregnancy leads to distinct changes in maternal cholesterol metabolism, whereas embryonic cholesterol concentrations and cholesterol metabolism genes are not affected. The trophoblast : embryoblast cholesterol ratio suggests a higher metabolic activity of the embryoblast in diabetes. The findings of the present study imply independent and functional cholesterol metabolism in the mammalian embryo before implantation.
Reproductive science is central to our understanding of biology, translating to biological processes across many organ systems. The Society for Reproductive Biology conference review provides a focused summary of symposia at the 2016 annual meeting. The presentations highlight the breadth of reproductive research in Australia and New Zealand and its potential to affect the fertility and health of future generations.
Kisspeptin neurons in the brain are crucial for the hormone surge required for ovulation, but are established before puberty. This study examined kisspeptin and brain clock gene rhythms (known to restrict kisspeptin action) in young mice. The data show that the kisspeptin peak is not seen prior to puberty and there is incomplete development of clock gene rhythmicity at this time.
In this study we investigated the expression of the LH receptor (LHR) gene during dominant follicle selection in Bos indicus cattle. The main finding was that the early deviation of the dominant follicle in this subspecies is driven by the differential expression of full-length LHR and its isoforms in small follicles. This finding will contribute to explaining the differences in ovarian physiology between B. indicus and Bos taurus.
Deficiencies in the initiation of embryo elongation play a major role in early embryonic mortality in the pig. This study demonstrates that embryos encapsulated and cultured in alginate hydrogels with the integrin-binding Arg-Gly-Asp (RGD) sequence had increased embryonic survival and modulation of gene expression to support increased steroid production and adequate immune responsiveness, with a larger number exhibiting the morphological changes compared to other in vitro treatments in this study. These results illustrate the importance of the integrin-binding RGD peptide sequence for stimulating the initiation of embryo elongation and improving embryo survival.
Decidualisation and vascular remodelling are fundamental for placentation and pregnancy success. Disruption of endogenous lysophosphatidic acid signalling modified the development of uterine vessels with consequences in the formation of the decidua and placenta, compromising the growth of embryos. Defects in these mechanisms could appear as obstetric complications, like implantation failure, positioning lysophosphatidic acid as a regulatory key lipid at implantation.
High embryo loss during early pregnancy in pigs is still an unresolved issue. Comparing the proteomic profile of the endometrium harvested from crucial stages of early pregnancy (Days 12–13 and 15–16) with the proteomic profile of tissue from corresponding days of the oestrous cycle revealed the presence of proteins unique for early pregnancy that are involved in adhesion, angiogenesis and cytoskeletal organization. The results of the present study may help us understand the causes of early pregnancy loss in pigs.
Binding of spermatozoa to the egg coat is a key step in fertilisation and provides a mechanism for reproductive isolation and sexual selection. To test this theory we investigated the molecular evolution of the ZP3 gene and its encoded sperm-binding region in a diverse murine rodent group. Our analyses provides evidence for positive selection on the sperm-binding region in several murine lineages, but the nature of the selective force remains unresolved.
The aim of this study was to develop a new genome preservation technique for goose species. According to our results, goose primordial germ cells (PGCs) migrate between 69 and 84 h of development. The goose blastoderm contains PGCs and by isolating and injecting these blastodermal cells we were able to generate chimeras. Altogether, this method could contribute to the cryopreservation of this species.
The addition of 20 mM glutamine to the freezing extender significantly improved post-thaw sperm motility, acrosome integrity, membrane integrity and mitochondrial activity. The exposure of spermatozoa to glutamine enhanced their γ-GCS activity and GSH synthesis, while decreasing ROS accumulation, LPO and DNA damage. Therefore, glutamine protects spermatozoa against ROS-induced cryodamage by enhancing GSH synthesis.
Enzymatic disaggregation of murine ovaries yielded higher numbers of morphologically intact follicules than previously reported. The molecular markers DAPI, CMXRos and alpha-tubulin were applied to assess post-harvest follicular morphology, mitochondrial function and cellular cytoskeleton respectively. A new preparation of animal origin-free collagenase IV caused more damage to follicular integrity, mitochondrial function and the cytoskeleton than enzyme-free mechanical isolation, but another preparation of collagenase IV ovarian disaggregation gave the highest yield of morphologically intact follicles containing viable mitochondria.
Seminal plasma bathes the sperm upon ejaculation but its function has yet to be fully defined. This study sought to characterise the effect of seminal plasma from bulls of high or low fertility on sperm function. Seminal plasma reduced osmotic resistance of epididymal sperm, regardless of whether it was from high or low fertility bulls.
The importance of the oviduct for different reproductive processes is known; however, the molecular mechanisms underlying oviductal regulation are not fully understood. The results of the present study demonstrate that gene expression in the oviduct is regulated during the oestrous cycle, with some oviductal proteins that could be related to several reproductive processes being described for the first time. These findings are very important in our understanding of the different processes that take place in the oviduct as fertilisation or early embryo development.
The expression of IL-11 is stimulated by LH/hCG in theca cells of preovulatory follicles via PKA-MAPK pathway and TLR4 activation. IL-11 increases progesterone production by stimulating StAR expression.
The peripubertal period is considered a critical stage of reproductive development and more vulnerable to the action of toxic agents, such as BPA, which can lead to impaired sexual development. We investigated the exposure to BPA during the peripubertal period and eEvidencing a reduction in the number of Sertoli cells, histopathological abnormalities and changes in sperm morphology. Therefore, BPA may silently impair testicular postnatal development in rats.
Subsequent infertility and testicular cancer are major problems for boys with undescended testis. This study aims to examine whether mouse has similar postnatal hormonal changes as boys, so it can be used as a model to study human testis development. Our results demonstrated that mouse can be used as a model for human minipuberty.
Bull semen quality traits are vital parameters in evaluating the fertility potential of bulls. In the present study we demonstrated that a single nucleotide polymorphism within the exonic splicing enhancer motif caused aberrant splicing of the RAB, member of RAS oncogene family like 2B (RABL2B) gene, and that semen quality differed among Chinese Holstein bulls with different RABL2B genotypes. These results also provide a novel research idea for further elucidating the complex molecular mechanism underlying the regulation of bull fertility.
Pannexins (Panx) are proteins that form functional single membrane channels that have not yet been described in dogs. The aim of the present study was to detect Panx1, Panx2 and Panx3 in frozen–thawed dog semen. All three Panx channels were present in dog spermatozoa and increased propidium iodide (PI) permeability in frozen–thawed dog spermatozoa, suggesting that the percentage of PI-positive spermatozoa used as an indicator of non-viable cells may lead to overestimation of non-viable cells.
Porcine embryos contain substantial amounts of lipid, with little known regarding its metabolic role during development. This study investigated the association of lipid metabolism with carbohydrate substrates in the culture medium and revealed positive effects of adding L-carnitine, a limiting co-factor required for lipolysis, on early cleavage and blastocyst quality. Supplementing medium with L-carnitine is a useful strategy to improve the success of porcine blastocyst vitrification.
Maternal metabolic disorders (e.g. obesity and diabetes in women or a negative energy balance in dairy cows) are associated with altered metabolic profiles, which can impact oocyte quality and thus fertility. We showed that altered glucose can differentially affect oocyte quality in the presence of elevated free fatty acids. These results further highlight the importance of maternal metabolic health for fertility.
Although oocyte cryopreservation is desired for the preservation of female germplasm, the developmental competence of vitrified porcine oocytes has been notoriously low due to unclear reasons. We investigated the effects of vitrification of porcine oocytes at the immature stage. Vitrification triggered premature nuclear resumption and nucleolar fragmentation from which some oocytes could recover, suggesting that enhancement of recovery processes might be a possible way to improve competency.
Successful artificial fertilisation primarily depends on two characteristics of male quality: 1) the maintenance of high sperm viability during storage and 2) the effective activation of sperm motility. This study identified optimal conditions for sperm motility activation in the critically endangered booroolong frog. Results reported make a significant contribution to the growing field of amphibian reproduction technologies.
Sex-specific differences have been reported in most of the diseases. This review provides data on differential adaptation of male and female fetuses in utero in response to maternal nutritional, physiological and environmental insults resulting in sex-specific differences. Because sex differences are associated with fetal outcome and survival, it is of importance to study the underlying biological mechanisms to improve both pre-natal and neonatal care.
This study provides evidence that natriuretic peptide C and steroids interact to slow oocyte nuclear maturation and to enhance oocyte-cumulus communication in cattle. Moreover, it indicates that exposure of the cumulus–oocyte complex to physiological concentrations of these hormones is beneficial to oocyte developmental competence. Therefore, the dataset is of relevance for the progress of oocyte biology and for the improvement of in vitro maturation outcomes.
This paper describes findings during a unique opportunity to monitor placental structure and function throughout pregnancy in the under-researched zebra. Zebras are more donkey-like than horse-like in placental structure, rate of fetal development and gestation length. The results highlight the retention of unique reproductive mechanisms across the Genus Equus despite many other evolutionary changes within the member species.
A combination of permeating and non-permeating cryoprotectants and freezing rates was used to successfully cryopreserve saltwater crocodile spermatozoa. Although glycerol concentrations >1.35 M had an inhibitory effect on motility before freezing, 0.68 M glycerol combined with 0.2 M sucrose and post-thaw washing of spermatozoa in capacitating media resulted in motility of between 12% and 14.2%, the highest ever recorded for this species.
Andrographolide should be prudently consumed by women attempting to conceive. The aim of the present study was to investigate the effects of andrographolide on oocytes. The findings indicate that andrographolide may disrupt mouse oocyte meiotic maturation and fertilisation potential by blocking cytoskeletal reorganisation. This study provides an important platform for understanding the potential adverse effects of andrographolide on female fertility.
In cattle, a major limitation of the success of IVF is the developmental competence that oocytes acquire during ovarian stimulation. The aim of the present study was to better understand the follicular conditions associated higher versus lower embryo yields. We revealed that the level of follicular differentiation (timing) is the main cause of failure and provide new biomarkers to identify such follicular conditions to adapt the ovarian stimulation protocol to individual animals.
Endo-siRNAs play an important role in mouse oocyte meiosis but the function of endo-siRNAs in other species is unknown. In this study, we found that an endo-siRNA deficiency resulted in oocyte spindle abnormalities and apoptosis, suggesting that endo-siRNAs are indispensible for oocyte maturation in pigs. This study unequivocally demonstrates an essential function for endo-siRNAs in mammals.
The association between bovine endometrial growth and prostaglandin (PG) F2α–PGF2α receptor (PTGFR) signalling activation is unknown. In the present study, cell proliferation and the expression of growth factors essential for endometrial growth were upregulated by PGF2α-PTGFR signalling activation by fluprostenol in bovine endometrial explants in vitro. These results indicate that PGF2α-PTGFR signalling activation could be involved in endometrial growth.
uPA shRNA lentivirus system induced by Dox inhibited the expression of uPA in TM4 cells. Through injecting the lentivirus into mice testis, we found that downregulation of uPA in mice testis decreased the fertility of male mice, which may be caused by a reduction in sperm motility. The inducible uPA shRNA system is safe and reversible to regulate male fertility.
This work demonstrates that estradiol through the peripheral nervous system modulates the ovarian physiology, favoring the physiological luteolysis. The objective of this work was to demonstrate whether estradiol in superior mesenteric ganglion modifies the release of ovarian progesterone, estradiol, nitric oxide and noradrenaline on DII day. The ganglionic stimulation produces a decrease in the ovarian release of progesterone and estradiol by an increase of nitric oxide and decrease of noradrenaline.
In PCOS, elevated levels of plasma androgens affects the quality of oocytes and ovulation rate, and causes anovulation in women of reproductive age. We studied the mechanism in a mouse model of PCOS, and showed that intracytoplasmic oxidative stress in oocyte via increase in histone acetylation and decrease in DNA methylation and histone dimethylation alters epigenetic modification. Consistently, mRNA expression of DNA methyltransferase-1 and histone deacetylase-1 was decreased with PCOS. There was a significant correlation between ROS production and increased histone acetylation. We concluded that antioxidant therapy in PCOS is a viable approach to reduce the adverse effects of epigenetic alterations.
The notable pathophysiological event that occurs in testicular torsion–detorsion (T/D) is ischaemia–reperfusion (I/R), which lacks efficient clinical treatment. Herein we describe, for the first time, the protective effects of polydatin, a traditional Chinese medicine, against testicular T/D injury in the rat. Our findings may provide new clues for male infertility associated with testicular torsion.
The reproductive effects of melatonin have been extensively studied, but its involvement in the local control of ovarian physiology has not yet been clarified. The present research, which was undertaken to study the effects of physiological levels of melatonin on the main parameters of swine granulosa cell function, documents that the hormone is involved in the modulation of ovarian follicle growth and development.
Resistin and visfatin, two adipokines, modulate reproduction in the gonads, but their actions at the hypothalamic–pituitary level are not known. We showed in vitro that these hormones decreased LH secretion from mouse gonadotroph cells and that in vivo visfatin may be a myokine as well as an adipokine in mice. Our findings suggest that these hormones may influence mouse female fertility by regulating LH secretion at the pituitary level.
The factors initiating puberty have not been clearly revealed. The present study compared serum total and high molecular weight (HMW) adiponectin levels between girls with central precocious puberty (CPP) and age-matched controls. Total adiponectin levels were low, but HMW adiponectin levels were high in girls with CPP, which probably leads to decreased inhibition of gonadotrophin-releasing hormone neuronal activity. This may provide an insight into how adipokines are involved in the initiation of puberty.
The selection of fertile males is important to augment fertility in cows, and breeding soundness examinations may not provide information on the fertility potential of bulls. Expression levels of seminal plasma RNAs may be used to predict the fertilising ability and cryotolerance of bull semen. Such non-invasive tests using seminal plasma may aid in the assessment of the health of the reproductive tract and in the selection of males for breeding.
The developing fetal brain is a potent target for endocrine chemical disruption by bisphenol A (BPA) because of its lipophilicity. In the present study, perinatal exposure to BPA changed the expression of genes regulating the hypothalamic–pituitary–testis (HPT) axis at the hypothalamic, pituitary and testes levels. Maternal exposure to BPA during fetal differentiation of the sexually dimorphic nucleus of the hypothalamus caused reprogramming of the HPT axis in adult male offspring
Although giant pandas have been described as mono-oestrus spring breeders, males exposed to oestrous females outside this timeframe exhibit breeding behaviours and interest in mating. Urinary androgens and sperm parameters were quantified for males exposed to females expressing oestrus during spring, autumn, or winter. The data from this study showed a rapid physiological readiness of male giant pandas to mate in response to female oestrous cues within or outside of the normal breeding season and may suggest a facultative seasonal reproduction with a “female-induced rut”.
In vitro growth of secondary follicles isolated from the vitrified ovarian cortex allows a better understanding of their complex development and of obtaining healthy follicles. The aim of this study was to investigate how the medium composition affects the viability and growth rate of the isolated secondary follicles. This technique could become a strategy to preserve the reproductive potential of females.
Reduced fetal growth can contribute to a greater risk of later metabolic disease, but the key mechanisms remain unknown. Herein we report findings from a large animal model (sheep) in which fetal growth was restricted by reducing maternal food intake and show that once the offspring become obese, they exhibit increased abundance of molecular markers of metabolic stress in the fat and liver. This could represent a primary mechanism by which growth-restricted offspring are at greater risk of metabolic ill health in later life.
Equine immature oocytes are classified as expanded or compact and are matured in the laboratory to obtain offspring; higher maturation rates are reported for expanded oocytes. The aim of this study was to assess whether differences in the maturation capacity of these oocytes is related to differences in glucose uptake, metabolism or apoptosis. Consistent metabolic and genomic differences were found between expanded and compact oocytes: compact oocytes consumed more glucose but matured less than expanded oocytes. This indicates that the maturation requirements vary for compact and expanded oocytes.
The zona pellucida (ZP) is an extracellular matrix formed by few glycoproteins that covers the oocyte and plays an important role during fertilisation. The identification of ZP glycoproteins in carnivores is relevant for an understanding of sperm–ZP interactions and species specificity. In this study, molecular and in silico analyses demonstrated the presence of the ZP1 gene in four families (Felidae, Mustelidae, Odobenidae and Ursidae), whereas in three families (Canidae, Otariidae and Phocidae) ZP1 is pseudogenised. This information could be relevant for the development of more specific and efficient contraceptive vaccines for carnivores.
Inflammation plays an important role in the initiation of preterm birth, which remains the largest cause of neonatal deaths. In the present study, components of the protein synthesis machinery were significantly increased with labouring compared to non-labouring fetal membranes and myometrium, and blockade of protein synthesis significantly reduced inflammation in the myometrium. These results may provide further insight into the pathways involved in the initiation of preterm birth.
One of the predominant causes of anoestrus is a low level of ovarian oestrogens. Herein, we investigated the association of the oestrogen biosynthesis regulator CYP19A1 with the risk of anoestrus in buffaloes and found three SNPs. The risk alleles in these SNPs were significantly associated with lower levels of estradiol and antioxidants and higher incidence of oxidative ovarian damage and anoestrus.
Ovum pick-up and in vitro embryo production can be used in dairy heifers. However, production results are often disappointing when animals are underfed. A short-term dietary supplement with propylene glycol (400 mL of PG or water/drench, daily drenching at 1600 hours for the first 9 days of the oestrous cycle), given to feed-restricted heifers, was able to restore the expression of selected genes in cumulus cells and blastocysts to levels seen in correctly fed heifers.
Is the temperature in a preovulatory follicle lower than in adjacent tissues? Using a novel non-invasive approach it was demonstrated that bovine follicular fluid before ovulation is cooler than the uterine surface and deep rectal tissues, whereas temperature is not reduced in follicles suffering ovulation failure. Follicular antral temperature could become a more valuable indicator of oocyte potential than a purely morphological assessment.
Juvenile in vitro embryo transfer (JIVET) can increase the gain rate by reducing the generation interval, but the low quality of these oocytes leads to poor embryo production. In this study we hypothesised that oocyte quality could be related to omega 3 (linolenic acid, ALA) and omega 6 (linoleic acid, LA) concentrations in follicular fluid. No differences were found in ALA and LA concentrations in relation to follicle diameter. The addition of a high LA (omega 6) concentration to the IVM medium impaired oocyte competence to develop up to the blastocyst stage.
Toll-like receptors (TLRs) contribute to an exclusive protection system in the uterus during the oestrus cycle; however, the importance of TLRs in tissue repair within the involuting uterus is not known. Herein we show that TLRs are constitutively expressed in uterine cells and that the localisation pattern of TLRs in the endometrium varies with structural changes in the involuting uterus. These results suggest that TLRs have a physiological role in the uterine remodelling events during the post partum involution period.
Assisted reproduction techniques such as in vitro fertilisation and embryo culture have been shown to affect the size and anatomy of the newborn and the placenta in some species, but no information is available on this area in the horse. We evaluated foals and placentas from pregnancies resulting from natural conception, embryo transfer and transfer of in vitro-produced (intracytoplasmic sperm injection) embryos and found no significant differences between groups in size or weight of the foal or placenta and no differences in expression of 17 genes controlling placental function. Our findings suggest that the horse embryo differs from that of ruminants in its sensitivity to the in vitro environment, supporting the continued use of assisted reproduction techniques for commercial foal production.
Extravillous trophoblast cells are one of the main elements that are affected by maternal smoking during pregnancy. Quantitative changes in extravillous trophoblast cells could be evidence for the hypothesis that changes in these cells could affect fetal health by changes in normal placentation.
Humans may be exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), an environmental pollutant, via contaminated food, inhalation or skin contact. The effects of TCDD are exerted via binding to aryl hydrocarbon receptors (AhR). In this study we investigated the possible protective effect of resveratrol, an AhR antagonist, against testicular damage caused by TCDD exposure during pregnancy. The findings suggest that TCDD in combination with resveratrol results in more severe toxicity than administration of either drug alone.
The testis is the organ essential for spermatogenesis and male fertility. This paper profiles differences in DNA methylation levels during prepubertal porcine testis development, and provides new insights into mammalian testis development and represents a foundation for additional research using the pig as a model animal.
It is not known whether female accessory reproductive organs that play a major role in reproduction are vulnerable to chronic stress effects. This study revealed irreversible oxidative stress in the Fallopian tube following short or long-term chronic stress exposure, whereas uterus changes were reversible following short-term exposure but not after long-term exposure. This study indicates that stress-induced reproductive failure may also be due to alterations in the accessory reproductive organs.
Genetic background can help to explain idiopathic cases of recurrent pregnancy loss (RPL), which make up about 50% of total cases. Here, we have evaluated the genetic profiles of women experiencing RPL by analysing polymorphisms in the NOS2, PTGS2 and VEGFA genes. We found a higher incidence of a polymorphic variant in the NOS2 gene in the RPL group, suggesting a role for this gene in RPL risk, possibly due to oxidative stress mechanisms.
Hormones in plants may provide an important trigger for activating breeding activity in Kākāpō, a critically endangered New Zealand parrot. By comparing native and Australian parrots for their ability to respond to steroid hormones, we discovered novel sequences in the receptivity of parrots to oestrogenic compounds. Receptor modeling revealed that altered interactions with plant oestrogens in parrots may enhance the physiological pathways linked to fertility and successful breeding.
For wild rodents such as the agoutis, the combination of gonadal tissue cryopreservation and xenotransplantation could help promote germplasm conservation and reproduction, especially in the case of genetically valuable individuals. The present study demonstrates that xenografted agouti ovarian tissue, fresh or vitrified, is able to promote the return of ovarian activity in ovariectomised SCID C57B1/6 mice.
Tumor suppressor protein p53, known widely as the guardian of genome preventing cancer formation, is also involved in physiological apoptosis of germ cells in testes. The study used a mouse model to reveal that germ cell apoptosis during the first round of spermatogenesis can be efficiently mediated by p53-independent mechanisms, but activation of these mechanisms requires engagement of multicopy Y-chromosome long arm genes. The role of Y-chromosome genes in regulation of testicular apoptosis was demonstrated for the first time.
Fertilisation and development of the mammalian egg is still not well understood, illustrated by low efficiencies of assisted reproductive technologies. The role of a cell membrane receptor for calcium (CASR) was studied, using pig spermatozoa and eggs as models. Significant effects were demonstrated by stimulating this receptor at different steps of the process. These findings are useful for future basic and applied research.
Juvenile in vitro embryo transfer (JIVET) can increase the genetic gain rate by reducing the generation interval, but the low quality of the oocytes and higher oxidative levels leads to poor embryo production. In the present study we hypothesised that melatonin could be a suitable tool for improving oocyte competence in juvenile goats. The results show that melatonin is present in the follicular fluid in juvenile goats and its addition to the in vitro maturation medium reduces oxidation and increases embryo development showing its potential role for JIVET.
Taking advantages of the clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated (Cas) 9 system, we achieved a precise single-nucleotide substitution in the growth differentiation factor 9 (GDF9) gene using a single-stranded oligo deoxynucleotide as a homology-dependent repair template with a relatively high efficiency in order to increase litter size in goats. The present study provides an alternative approach for introducing defined point mutations in large animal models for the improvement of significant traits, as well as for the functional validation of key variants.
The application of genome storage in conservation is severely constrained by our limited access to reliable assisted breeding techniques. This is particularly so for marsupials, in which the corpus luteum, and thus cycling, is not affected by agents used to control ovarian function in eutherian mammals. Herein we report progress on the use of a single-treatment long-acting suppressor of pituitary function to reset cycling and ovulation in a marsupial.