Selective breeding of chickens for high growth rate and other production traits has led to the modern commercial broiler, a bird that has the genetic potential for reaching an average body weight of 2.7kg within 6 weeks of hatch. However, the breeding stock for modern broilers has to be feed controlled in order to lay large numbers of viable hatching eggs. Broiler breeders, when fed ad libitum, have a propensity to produce internal ovulations, double-yolked, misshapen or shell-less eggs. This is due to the release of multiple ova at ovulation, which results in a significant loss of production. Feed control has been shown to mitigate this effect but welfare concerns have been raised as to the side-effects for the birds. The main objective of this research was to determine the genetic basis for the regulation of ovarian follicle selection and its dysfunction in ad libitum-fed broiler breeders, and how this might be addressed by genetic selection to limit the impact on the management and welfare of future broiler breeders. A multi-layered statistical, expression profiling and cluster analysis of ovarian gene expression data from a microarray study was carried out to identify candidate genes for further study.Key stages of development were investigated for feed restricted and ad libitum-fed broiler breeders. Several gene candidate genes were validated by qPCR in a comparison of different ovarian tissues in layer type hens for subsequent analysis in broiler breeders. Sequencing of the founders of an Advanced Intercross Line (AIL) of commercial broiler breeders and White Leghorn layers was performed covering 3 regions of each of the primary candidate genes in order to identify genetic variation that could account for differences in follicle number between broilers and layers. Expression data from a microarray study highlighted a number of potential candidate genes for regulation of follicle development. One of these genes, Platelet Derived Growth Factor Receptor Like (PDGFRL), shares significant sequence homology with the active domains of Platelet Derived Growth Factor Receptor β. Expression profiling in layers showed peak PDGFRL expression in 5-6 mm follicles and the F2 follicle (P <0.001). PDGFRL was also up-regulated in response to ad libitum feeding in broiler breeders in 6-8 mm follicles (P<0.016), the point at which follicle selection and recruitment is considered to occur. In addition to this, while PDGFRL expression remains relatively constant between tissues under ad libitum conditions, it shows a clear reduction in expression (P <0.001) in prehierarchical follicles relative to the stroma and the F1 follicle under feed restriction. This observation is consistent with results from the original microarray study. Sequencing of the AIL Founders highlighted several SNPs in the broiler that have the potential to be used as markers for incorporation into commercial selection programs. EST alignment in preparation for targeted sequencing of PDGFRL also highlighted three potential forms of the protein, each with a different 5’ starting sequence. Initial investigation has shown all three to be expressed in ovarian follicles. QPCR in a panel of 13 tissues shows marked differences between the 3 variants, implying different and perhaps specialised roles for each. The PDGFR family has a potential role in steroidogenesis, and the expression profiling, combined with the clear effect on expression from ad libitum feeding in broiler breeders, suggest that PDGFRL is a strong candidate for involvement in the regulation of follicle development GDF9, shown to be associated with multiple ovulation in sheep, and FSH receptor, a mediator of neuroendocrine signalling to the ovary, were also investigated. They behaved as expected in layer type birds but both showed significant differential expression (P = 0.005 and 0.018 respectively) as a result of ad libitum feeding in broiler breeders. Though these two genes have been extensively investigated, these are previously unobserved effects. SNPs have also been identified in these genes which have the potential to be used as markers for incorporation into commercial selection programs. To fully exploit these results, additional investigation is recommended to confirm these results in commercial populations and to determine how they can be employed to best effect.

No description available.

Diss. (sammanfattning) Umeå : Umeå universitet, 2009. / Härtill 4 uppsatser.

Diss. (sammanfattning) Umeå : Univ., 2007. / Härtill 4 uppsatser.

The harvesting of immature mammalian oocytes (eggs) and their maturation in a laboratory environment, known as in-vitro maturation (IVM), provides an alternative to the harvesting of mature oocytes for in-vitro fertilisation (IVF) programs. The nutrient environment of an oocyte matured in vitro is known to have a significant effect on its potential to successfully mature, and it is desirable for the in-vitro nutrient environment to mimic the natural environment in vivo. This thesis describes an interaction between mathematical modelling and experimental investigation designed to build upon understanding of the nutrient environment of the oocyte in vivo, which is difficult to determine via experiment alone. A general mathematical model of nutrient transport to the oocyte, through its surrounding cumulus cells is developed. This model is applicable in-vivo and in-vitro across several species and to a number of important nutrients. Nutrient transport in this system - the cumulus-oocyte complex (COC) - is of particular importance, as it is this system that is normally removed for IVM treatments, and its solution under in-vivo conditions allows the nutrient concentration reaching the oocyte to be determined, given a known concentration immediately surrounding the COC. To successfully apply this model, parameters representing the rate of nutrient transport into cells within the COC must be accurately determined. These parameters are determined by a combination of experimental procedures and mathematical modelling in the case of an important nutrient to oocyte development, glucose. This work gives insight into the concentration dependence of glucose uptake into cell types that are important in regulating oocyte development, and to the behaviour of the oocyte itself with regard to glucose uptake. Finally models to describe the transport of two key nutrients, oxygen and glucose, from the vascular system in the ovary, through the ovarian follicle to the oocyte are developed. These make use of experimental results found in the study of glucose transport in the COC, and show that the geometry of the follicle has a significant impact on the nutrient environment of the COC, and hence by inference the nutrient environment of the oocyte. Work discussed in this thesis has been published [31, 156] and submitted for publication [30]. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1374636 / Thesis (Ph.D.) -- University of Adelaide, School of Mathematical Science, 2009

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 4 uppsatser.

Chemotherapy treatment in premenopausal women has been linked to premature ovarian failure (POF), and hence infertility, through ovarian follicle loss. The exact mechanisms that lie behind this loss are unclear and so the action of two commonly used chemotherapeutic agents were compared here. Cisplatin is a DNA cross-linking agent commonly used in the treatment of ovarian, lung and bladder cancers, while the anthracycline doxorubicin is commonly used to treat leukaemia and breast cancer. Neonatal mouse ovaries were cultured in vitro and exposed to cisplatin or doxorubicin in order to determine their effects on primordial and early growing follicles. Both drugs caused a dose dependant follicle loss but targeted different cell types. Cisplatin caused a significant increase in follicles with unhealthy oocytes; furthermore primary stage follicles were the follicle class most affected (up to 98% classified as unhealthy compared with 13% in control, p<0.001). In contrast, doxorubicin caused a significant increase in follicles with unhealthy granulosa cells and affected all follicle stages present. When the mechanism of cell death was further investigated, apoptosis was the main pathway through which these drugs cause ovarian cell death. Doxorubicin in particular caused a significant increase in apoptosis of ovarian somatic cells including the granulosa cells and stroma. Imatinib mesylate, a tyrosine kinase inhibitor which is also used as a chemotherapeutic agent, has been implicated as a potential therapy to block the ovotoxic effects of cisplatin. Results here confirm this finding (29% of follicles classified as unhealthy in the cisplatin only group compared to 8% in the cisplatin and imatinib co-treatment group, p<0.001) and found further, that imatinib was unable to protect against doxorubicin-induced damage (28% of follicles classified as unhealthy in the doxorubicin treated group compared to 19% in the doxorubicin and imatinib cotreatment group). Imatinib treatment alone in newborn ovaries caused a significant increase in the number of follicles present at the end of culture compared to control (402±43 in the imatinib group compared to 188±34 in control, p<0.001), which is likely due to an effect on follicle formation. In conclusion, the work presented in this thesis demonstrates drug specific actions of cisplatin and doxorubicin on the mouse ovary. This suggests that any therapy designed to confer ovarian protection in the future may have to be tailored to be drug specific.

Ovarian follicles in women are fluid-filled structures in the ovary that contain oocytes (eggs). A dominant follicle is physiologically selected and ovulates during the menstrual cycle. We examined the echotexture in ultrasonographic images of the follicle wall of dominant ovulatory follicles in women during natural menstrual cycles and dominant anovulatory follicles which developed in women using oral contraceptives (OC). Texture features of follicle wall regions of both ovulatory and anovulatory dominant follicles were evaluated over a period of seven days before ovulation (natural cycles) or peak estradiol concentrations (OC cycles). Differences in echotexture between the two classes of follicles were found for two co-occurrence matrix derived texture features and two edge-frequency based texture features. Co-occurrence energy and homogeneity were significantly lower for ovulatory follicles while edge density and edge contrast were higher for ovulatory follicles. In the each feature space, the two classes of follicle were adequately separable.</p><p>This thesis employed several statistical approaches to analyses of texture features, such as plotting method and the Mann-Kendall method. A distinct change of feature trend was detected 3 or 4 days before the day of ovulation for ovulatory follicles in the two co-occurrence matrix derived texture features and two edge-frequency-based texture features. Anovulatory follicles, exhibited the biggest variation of the feature value 3 or 4 days before the day on which dominant follicles developed to maximum size. This discovery is believed to correspond to the ovarian follicles responding to system hormonal changes leading to presumptive ovulation.</p>

Ovarian follicles in women are fluid-filled structures in the ovary that contain oocytes (eggs). A dominant follicle is physiologically selected and ovulates during the menstrual cycle. We examined the echotexture in ultrasonographic images of the follicle wall of dominant ovulatory follicles in women during natural menstrual cycles and dominant anovulatory follicles which developed in women using oral contraceptives (OC). Texture features of follicle wall regions of both ovulatory and anovulatory dominant follicles were evaluated over a period of seven days before ovulation (natural cycles) or peak estradiol concentrations (OC cycles). Differences in echotexture between the two classes of follicles were found for two co-occurrence matrix derived texture features and two edge-frequency based texture features. Co-occurrence energy and homogeneity were significantly lower for ovulatory follicles while edge density and edge contrast were higher for ovulatory follicles. In the each feature space, the two classes of follicle were adequately separable.</p><p>This thesis employed several statistical approaches to analyses of texture features, such as plotting method and the Mann-Kendall method. A distinct change of feature trend was detected 3 or 4 days before the day of ovulation for ovulatory follicles in the two co-occurrence matrix derived texture features and two edge-frequency-based texture features. Anovulatory follicles, exhibited the biggest variation of the feature value 3 or 4 days before the day on which dominant follicles developed to maximum size. This discovery is believed to correspond to the ovarian follicles responding to system hormonal changes leading to presumptive ovulation.</p>

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 4 uppsatser.