Bioscientifica Proceedings

Summary. Reproductive traits can range from lowly to moderately heritable. Genomic technologies provide a powerful tool for improving selection for traits that are lowly heritable, sex-linked, or not expressed until later in life. Therefore, as genomic technologies become a part of selection decisions, there is a critical need to understand how specific gene variants affect reproductive traits in cattle. Both classical quantitative genetics approaches and geno...

The expression and localization of selected growth factor systems and extracellular matrix (ECM) components that may influence oocyte maturation and fertilization within the mammalian oviduct are reported. Fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF) systems could be detected by use of RT–PCR, RNase protection assay (RPA) and immunohistochemistry in bovine follicles, bovine cumulus–oocyte complexes (COC) and bovine and marmoset oviduct...

Experiments were conducted to further our understanding of the cellular and molecular mechanisms that regulate luteal function in ewes. Inhibition of protein kinase A (PKA) reduced (P < 0.05) secretion of progesterone from both small and large steroidogenic luteal cells. In addition, the relative phosphorylation state of steriodogenic acute regulatory protein (StAR) was more than twice as high (P&hairsp;<&hairsp;0.05) in large vs small luteal cells. Large steroidogenic...

High numbers of lipid droplets (LDs) in mammalian eggs are stored and maintained throughout embryo development without marked signs of their utilization. It was previously demonstrated in large domestic mammals that removing lipids from the zygote does not influence post-implantation development in terms of the rate of delivered offspring. Previously studied pig and cow eggs contain considerable amounts of LDs, while mice have a very low level of ooplasmic lipids, which allows...

Summary. Our understanding of the synthesis and production of follicular steroids and prostaglandins (PG) in the pig is based largely on in-vitro studies with granulosa and theca interna tissues obtained from Graafian follicles at various stages of maturation. As the follicle enlarges before the LH surge, granulosa cells exhibit a decrease in FSH receptors and are less responsive to FSH in terms of cAMP production. Concurrently, there is an increase in gr...

The development of new technologies that would increase the efficiency for generation of transgenic livestock and would overcome some of the problems associated with random insertion of the transgene will greatly benefit animal agriculture. A potential alternative technology to pronuclear injection for the generation of transgenic pigs involves the isolation, culture and genetic manipulation of cell lines that can be reintroduced into the embryo for participation in the f...

The resumption of ovarian follicular development during lactation and after weaning in sows is a complex process that ultimately determines rebreeding efficiency of sows. Ovarian follicular development before weaning is heterogeneous because multiple patterns of development are observed when individual sows are compared. Sows can have relatively inactive ovaries before weaning with follicles of < 2 mm in diameter. Other sows have nonovulatory follicular waves in which...

An overview is presented on the structure and function of the pig oviduct in relation to sperm capacitation and oocyte development in vivo. In pigs, a functional sperm reservoir is established in the uterotubal junction-isthmus when sperm deposition occurs before ovulation. Capacitation is assumed to occur in this location, and spermatozoa progress towards the ampullaryisthmic junction at about the time of ovulation as a consequence of capacitation and hyperacti...

In pigs, as in other species, fetal growth retardation is associated with reduced birth weight and increased risk of fetal and neonatal death. As there are few opportunities after birth to remedy the detrimental effects of low birth weight, it is important to understand both the intrinsic and extrinsic factors associated with inadequate fetal growth and to determine when growth retarded fetuses deviate from the growth trajectory of their normal sized littermates. Inadequately ...

Functional genomics is an experimental approach that incorporates genomewide or system-wide experimentation, expanding the scope of biological investigation from studying single genes to studying potentially all genes at once in a systematic manner. This technology is highly appealing because of its high throughput and relatively low cost. Furthermore, analysis of gene expression using microarrays is likely to be more biologically relevant than the conventional paradigm ...