Fiji | ResearchGate | Contact Zara
Investigating the Intrafollicular Factors Affecting Oocyte Competency
The overall aim of my research project is to improve outcomes of assisted reproductive technologies. In order to do this, my project uses sheep as a model species and is focussed on:
- investigating the key maturational events that occur during the period prior to ovulation in vivo
- using a combination of cumulus cell gene expression profiles and the timing of important developmental events (morphokinetic markers) to develop better biomarkers of oocyte competency in in vitro produced embryos.
- investigating the effects of supplementing different ratios of porcine GDF9 and BMP15 on oocyte competency in sheep.
New Zealand | Contact Charlotte
Factors Affecting Oocyte Quality in New Zealand Dairy Cows
Poor oocyte quality is a contributing factor to early pregnancy loss and poor conception rates in dairy cows. While the oocyte is successfully fertilised in most inseminated cows, a large proportion of these pregnancies are lost in the first week. To improve the reproductive performance of New Zealand dairy cows, the factors driving this early loss must be examined. Oocyte quality is one of these factors.
Oocyte quality is essential to early embryonic survival. Because the genome of the developing embryo doesn’t activate until the eight cell stage, maternal mRNA and proteins stored within the oocyte are required to guide and support early development. Consequently, when poor quality oocytes are fertilised they are less able to support this development and there is increased risk of early embryonic death. My research will test the hypothesis that factors such as disease, nutrition, and genetics, which are known to reduce fertility, affect oocyte quality.
New Zealand | Contact Orin
Aptamers are novel oligonucliotide sequences that can bind specifically to their target with high affinity. My research is focused on the development of an aptamer-based assay for the specific detection of BMP15 and GDF9 proteins in vitro. These proteins have already been shown to act as essential reproductive hormones in many mammalian species including sheep and cows. Therefore the ability to accurately measure these proteins in vitro may allow for an indication of reproductive success.
New Zealand | Contact Matire
The productivity of the dairy industry is reliant on the reproductive success of cows. The consequences of their long gestation period (~283 days) is, that to fit within a calendar year, the optimal time for mating coincides with the time of peak lactation. The increased energy demands of lactation results in dairy cows that are likely to be under high energy constraints during the mating period. Subsequently, oocyte quality and the ability to develop into a success embryo once fertilised is compromised.
The Pitman laboratory hypothesises that in some individual cows during peak lactation, the ovarian follicle may be unable to provide an optimal environment for successful oocyte maturation. Moreover, the components of follicular fluid have been assessed in the NZ dairy cow ;and found to be considerably different in several critical constituents, compared with that of dairy cows from other countries and with that of culture media. The divergence between the concentrations of constituents within follicular fluid to that in the gold-standard in vitro maturation (IVM) media (M199) is significant given the importance of these constituents on numerous processes involved in oocyte maturation, as discussed above. To address this, the Pitman group created two physiologically-relevant media containing concentrations of constituents that are representative of that measured in follicular fluid of NZ dairy cows.
My research will test the effects of culturing bovine oocytes in commercial IVM media compared to two physiologically-relevant media that represent a good and poor follicular microenvironment on (i) gap junction communication within the COC, (ii) timing of meiotic resumption (iii) expression levels of key genes and (iv) utilisation of amino acids.