Reproduction, Fertility and Development
Number 9 2016
The tammar wallaby has evolved a unique lactation strategy compared to eutherian mammals making it a valuable comparative model for lactation studies. In this study, the tammar wallaby mammary gland was investigated for changes in gene expression during key stages of the lactation cycle and differentially regulated genes were identified. These genes may play a crucial regulatory role in marsupial milk production, and are likely to play a related role in other mammals.
Altered sphingolipid metabolism has been suggested to cause sperm morphological abnormalities in Twitcher, a mouse model of Krabbe disease. However, our data demonstrate that a derangement of the hypothalamic–pituitary–gonadal axis, caused by severe brain degeneration, may contribute to Twitcher infertility. These findings may also contribute in further understanding of all cases of infertility associated with neurological impairment.
Despite a lack of cysteine in the protamine fraction of dunnart spermatozoa, the chromatin remains remarkably stable. Using a range of molecular techniques and under conditions known to fragment sperm DNA, we further confirm this phenomenon. Our results suggest that cysteine is present in the histone fraction of the chromatin and it may be functioning to conform tertiary and/or quaternary chromatin structure.
In cattle, a suboptimal pool of oocyte factors is suspected to contribute to the poor reproductive performance. Cows with high and low oocyte developmental potential in vitro were discriminated, and differential transcripts evidenced using microarrays; reverse transcription–quantitative polymerase chain reactionconfirmed altered expression for SLC25A16, PPP1R14C, ROBO1, AMDHD1 and MEAF6. These genes will be examined for polymorphisms that could be used in genomic selection.
Endometrial receptivity is a primary concern in fertility treatments. No significant differences in pregnancy rate, the number of gestational sacs and miscarriage rates were found with different endometrial thickness measurements in the present study, the largest study so far evaluating the role of endometrial thickness in oocyte donation cycles. Hence, embryo transfer can take place once endometrial thickness >5 mm has been observed in a single ultrasonographic evaluation, with no need for subsequent monitoring.
Reproductive toxicity screening relies on animal testing. We applied our in vitro follicle growth assay to screen for endocrine and gamete outcomes following exposure to compounds including an oil dispersant used heavily during the Deepwater Horizon oil spill. Here we show that in vitro follicle health can be monitored in vitro, which may help inform future human health exposure policy.
Knowledge of the molecular mechanisms regulating apoptosis in normal canine cyclic endometrium might lead to a better understanding of tissue changes associated with implantation and uterine pathological conditions such as cystic endometrial hyperplasia. The results of our work indicate that pro- and anti-apoptotic proteins regulate the balance between cell proliferation and death in the canine endometrium during the oestrous cycle.
Reproductive efficiency is controlled by genetics and environmental factors such as nutrition. Using a sheep model, we have discovered that mutations in the leptin receptor, a key pathway in the nutritional control of reproduction, are associated with reduced fertility. This has potential applications for the selection of sheep with improved reproductive efficiency as well as providing a new model to better understand how leptin regulates fertility in mammals.
Nutritional and environmental conditions around conception and during early embryonic development have significant effects on health and well-being in adult life. Here, we used a bovine heifer model to investigate the effects of rumen-protected fat supplementation on oocyte quality and embryo development with the aid of advanced mass spectrometry and molecular methods. Results show that rumen-protected fatty-acid supplementation affects oocyte lipid content and may pave the way towards a better understanding of reproductive disorders associated with nutritional impairments.
FSH and its receptor (FSHR) are essential for the development and function of the ovary. This study demonstrates for the first time a constant expression and immunolocalisation of FSHR in ovaries from adult mares and newborn fillies, together with the existence of tertiary follicles up to 4 mm in female neonates. Our results suggest an involvement of FSH in luteal function and oocyte maturation in horses.
The use of liquid bull semen in artificial insemination provides an ideal opportunity to maximise the number of inseminations per ejaculate through a lower number of spermatozoa per insemination dose. This study demonstrated that a temperature range of 5 to 22°C is not detrimental to liquid sperm function and that lowering the number of spermatozoa per liquid insemination dose from 5 to 3 million does not result in a significant decline in fertility. This reduction in sperm number allows for the better use of genetically superior sires leading to enhanced genetic gain.
Interspecies nuclear transfer can be a valuable tool for the preservation of threatened wildlife species; however, numerous challenges remain. Development of embryos reconstructed from wood bison donor cells transplanted into enucleated domestic cattle oocytes was affected as early as the 8–16-cell stage with altered cellular function and viability. These findings provide evidence for low blastocyst development rates and highlight the influence of interspecies communication in reconstructed embryos.
Early assessment of fertility is important for bull selection in a breeding program. The relationships of sperm membrane and DNA fitness with bull fertility were determined. Spermatozoa with membrane and DNA breaks in bull semen adversely affected field fertility following artificial insemination. Cow ova fertilised with semen possessing DNA-nicked spermatozoa demonstrated poor embryonic development in the laboratory.
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in daily life and have endocrine-disrupting properties that may affect reproductive and developmental processes. The purpose of this study was to investigate whether 1-hydroxypyrene – a biomarker of PAH exposure – was associated with sperm aneuploidy. The results suggest that exposure to PAHs may be associated with sperm aneuploidy. As this is the first such epidemiological study these findings require further replication.
Detection of sex, disease status and other genetic traits of horse embryos by biopsy before they are transferred would be a valuable breeding management tool. We found that accuracy differed between methods used for DNA amplification, but not between in vivo- and in vitro-produced embryos. The final high accuracy achieved (>95%) using DNA amplification and multiplex PCR supports clinical use of this technique.
Early pregnancy influences hormones in the blood of the mare, but little is known about local hormone concentrations in the reproductive tract, which is in direct contact with the developing equine embryo. We determined hormone levels in the oviduct of the horse and our main finding was that the concentration of the pregnancy hormone progesterone is significantly elevated in the oviduct after ovulation and on the side of ovulation. This study provides the basis for further research into embryo–maternal interactions in the equine oviduct.
Fertility is the most important factor regulating animal reproduction. The aim of the present study was to ascertain to what extent sperm proteins β-tubulin 2C, heat shock protein 10 and superoxide dismutase 1 (SOD1) were associated with bull fertility using molecular and bioinformatics approaches. We demonstrated that SOD1 was associated with in vivo bull fertility and that it interacts with key regulators of cell viability. The findings are significant because they reveal the paternal effect protein involved in bull fertility.
Polycystic ovary syndrome (PCOS), a common cause of female infertility, may be predetermined in the womb. Exposing mothers to excess amounts of an androgenic hormone may render their female offspring susceptible to developing PCOS due to altered regulation of androgen production-related genes in the offspring. This research has furthered our understanding of the mechanisms of PCOS and sheds light on disease prevention.
Rather little attention has been paid to the molecular mechanisms in the effects of heat treatment on Leydig cell function. In this study, testicular heat treatment led to Leydig cell hyperplasia and a reduction in testosterone levels. The findings of this study provide new insights into improvements in the treatment of male infertility.
What do you do when you have large volume of frozen semen from an endangered species with quality too poor to be used in assisted reproductive programs? Facing such a conundrum we tested a number of density-gradient centrifugation media, finding Percoll as the medium of choice for wild African elephant spermatozoa. Rather than discarding semen of inferior quality, density-gradient centrifugation can help select for better-quality and useable spermatozoa.