Reproduction, Fertility and Development
Number 8 2015
Embryos experience stress when they are grown in the laboratory, and this is believed to be detrimental to the embryo later in life. This article reviews the effects of in vitro conditions on the embryo and the mechanisms involved. By having a greater understanding of the mechanisms, we can potentially prevent stress during embryo growth in vitro.
Lipids are the main energy source for oocytes. Based on 3D-microscopic evaluation, a mature bovine oocyte contained 22 picolitres of lipids distributed as 3000 droplets occupying 3.3% of the cell volume. Extending the FSH treatment from 4 to 7 days yielded a higher proportion of mature oocytes with no effect on lipids. FSH starvation for 84 h resulted in failure of meiotic resumption and accumulation of large lipid droplets, indicating degenerative changes.
Sperm storage technologies aim to extend sperm longevity and increase the time available to achieve artificial fertilisation. Overall, results from this study on the booroolong frog indicate that increased oxygen availability is beneficial to sperm longevity, but that antibiotics are detrimental. The optimal storage protocols identified will allow spermatozoa from spatially separated breeding stock to be transferred among captive facilities, a tool that will assist the genetic management of this critically endangered species.
Tagging with multi-ubiquitin chains targets substrate proteins for recycling by the 26S proteasome, during which deubiquitinating enzymes (DUBs) remove multi-ubiquitin chains from the substrate to regenerate mono-ubiquitin. In this study, DUB inhibitors impaired porcine oocyte maturation, fertilisation and pre-embryo development by altering the turnover of oocyte proteins such as major vault protein. Thus, DUBs may promote the acquisition of oocyte developmental competence.
The integrity of sperm DNA is recognised as an important parameter of semen quality, but there are no published reports of this procedure for any amphibian. Validated as the first amphibian protocol for the assessment of sperm DNA fragmentation, the sperm chromatin dispersion test revealed three nuclear morphotypes representing varying degrees of DNA damage. This protocol has the potential to benefit assisted breeding programs using assisted reproductive technologies to support amphibian conservation efforts.
Embryo cryopreservation has huge potential to ensure the storage and worldwide distribution of elite germplasm. The aim of this study was to establish a standard procedure using specific cryoprotectant concentrations to avoid loss during cryopreservation procedures. Vitrification using 40% ethylene glycol resulted in superior embryo survival in sheep embryos from abattoir-derived oocytes. These results provide an easier option for embryo cryopreservation without compromising embryo survival.
Alpaca seminal plasma contains the protein β-nerve growth factor (β-NGF), which induces ovulation in females. We examined the effects of three doses of β-NGF and a gonadotrophin-releasing hormone (GnRH) agonist on ovulation rate and interval, corpus luteum diameter and plasma progesterone when administered to female alpacas and found that only ovulation rate varied. This suggests that there is no advantage to using β-NGF over more readily available and cheaper GnRH agonists to induce ovulation in alpacas.
This paper shows a direct relation between fertility and ROS production in sperm samples. The Fluorescein (CM-H2DCFDA) test combined with the SOF incubation could be considered a standard method for improving sperm-quality assessment. Ultimately, this technique could be a possible solution to the problem of fertility prediction in the laboratory.
Insulin plays an important role in the regulation of ovarian function; however, the specific molecular mechanism of its function remains largely unknown. This study found that insulin promoted folliculogenesis by facilitating germ-cell apoptosis within the cysts and upregulating oestrogen levels. This work established an effective model to study the function of insulin in folliculogenesis.
Changes in maternal diet during pregnancy can have long-lasting influences on the offspring’s health. In sheep, suboptimal nutrition during early-to-mid gestation results in enhanced fat deposition around the fetal heart. This is accompanied by increased abundance of genes that promote adipocyte synthesis. These adaptations may promote survival at birth but contribute to obesity in later life.
Diethylhexyl phthalate (DEHP) disrupts the physiological functions of endogenous hormones and induces abnormal development of mammals. However, the effects of DEHP exposure on folliculogenesis remain largely unknown. DEHP exposure significantly delayed the first meiotic progression of female fetal germ cells and accelerated follicle recruitment. DEHP exposure induced ovarian development deficiency, which was transgenerational in mice.
Low density lipoprotein receptor (LDLR) is responsible for the uptake of cholesterol-carrying lipoprotein particles into cells. The Ldlr deficient mice developed severe dyslipidemia and had significantly decreased female fertility. This study provides additional evidence for the role of Ldlr in regulation of lipid metabolism as well as female reproductive health during postnatal life.
Almost two thirds of the 65 documented Pteropus species (large bats called flying-foxes) are considered threatened with extinction. Our research aimed to provide foundational information from which to develop a method of semen collection, extension and preservation for use in male fertility assessments and artificial insemination. The successful collection of >400 semen samples from six Pteropus species, four which had never been characterised before, adds to the general knowledge of male reproductive biology in these species and advances the likelihood that artificial reproductive technologies may one day be used to assist conservation efforts.
Ovarian tissue cryopreservation by slow freezing and vitrification are techniques available to cancer-affected women to preserve their fertility before cancer therapy. Comparison of these two techniques in mouse ovarian tissue has demonstrated the adverse effects of ovarian tissue slow freezing but not vitrification on oocyte DNA quality and functional ability. Hence, vitrification may be preferred over slow freezing for ovarian tissue cryopreservation.
Ovum pick-up and in vitro embryo production is a technique that can be used in high genetic merit dairy heifers to produce large numbers of high quality embryos. Serum anti-Müllerian hormone (AMH) was positively correlated with the numbers and quality of in vitro produced embryos after superovulation. A simple dietary supplement, propylene glycol, which increased circulating insulin, glucose and IGF1, was able to further increase oocyte quality and embryo production in animals with high AMH levels.
Adenosine triphosphate, the energy substrate, can also be an extracellular signalling molecule. The aim of this study was to investigate the role of ATP signalling in murine luteal cells and the possible mechanism(s) involved. We revealed that ATP signalling can activate the P2X7 receptor and inhibited the proliferation of luteal cells.