Effects of FSH on the expression of receptors for oocyte-secreted factors and members of the EGF-like family during in vitro maturation in cattle.

FSH induces expansion of bovine cumulus-oocyte complexes (COCs) in cattle, which can be enhanced by oocyte-secreted factors (OSFs). In this study it was hypothesised that FSH stimulates COC expansion in part from direct stimulation of the epidermal growth factor (EGF)-like ligands amphiregulin (AREG), epiregulin (EREG) and betacellulin (BTC), but also in part through regulation of OSFs or their receptors in cumulus cells. Bovine COCs were cultured in defined medium with graded doses of FSH.

Estimation of taurindicine hybridization of American Zebu cattle in Brazil.

Our objective was to estimate Bos primigenius taurus introgression in American Zebu cattle. One hundred and four American Zebu (Nellore) cattle were submitted to mtDNA, microsatellite and satellite analysis. Twenty-three alleles were detected in microsatellite analysis, averaging 4.

Fibroblast growth factor-2 regulation of Sprouty and NR4A genes in bovine ovarian granulosa cells.

Fibroblast growth factors (FGFs) alter ovarian function, at least in part by inhibiting steroid hormone secretion and affecting survival of granulosa cells. The mechanism of action of FGFs in ovarian follicle cells is largely unknown; in the present study we identified the major pathways used by FGF2 in non-luteinizing granulosa cells cultured under serum-free conditions. FGF2 increased abundance of mRNA encoding SPRY1, 2, and 4, but not SPRY3.

Differential gene expression and developmental competence in in vitro produced bovine embryos.

The embryonic developmental block occurs at the 8-cell stage in cattle and is characterized by a lengthening of the cell cycle and an increased number of embryos that stop development. The maternal-embryonic transition arises at the same stage resulting in the transcription of many genes. Gene expression studies during this stage may contribute to the understanding of the physiological mechanisms involved in the maternal-embryonic transition.

Regulation and action of fibroblast growth factor 17 in bovine follicles.

Fibroblast growth factor 17 (FGF17) is a member of the FGF8 subfamily that appears to be relevant to folliculogenesis and oogenesis, as the prototype member FGF8 is an oocyte-derived protein that signals to cumulus cells. FGF8 has structural and receptor-binding similarities to FGF17, whose expression in the ovary has not been reported. In this study, we demonstrate localization of FGF17 protein to the oocyte of preantral follicles, and to the oocyte and granulosa cells of antral follicles.

Effect of follicle size on mRNA expression in cumulus cells and oocytes of Bos indicus: an approach to identify marker genes for developmental competence.

To identify the genes related to oocyte competence, we quantified transcripts for candidate genes in oocytes (H1Foo, H2A, H3A, GHR, GDF9, BMP15, OOSP1) and cumulus cells (FSHR, EGFR, GHR, PTX3, IGFII) using the follicle size model to select oocytes of better developmental quality. Follicles were dissected and distributed into four groups according to diameter as follows: 1.0-3.

Expression of fibroblast growth factor receptors during development and regression of the bovine corpus luteum.

There is evidence that fibroblast growth factors (FGFs) are involved in the regulation of growth and regression of the corpus luteum (CL). However, the expression pattern of most FGF receptors (FGFRs) during CL lifespan is still unknown. The objective of the present study was to determine the pattern of expression of 'B' and 'C' splice variants of FGFRs in the bovine CL.

Development and optimization of a fluorescent differential display PCR system for studying bovine embryo development in vitro.

Differential display is a widely used methodology to identify genes that are differentially expressed in biological samples. We developed a new protocol for the amplification and recovery of differentially expressed genes from extremely small initial amounts of RNA (10 to 25 pg mRNA) from preimplantation bovine embryos. The cDNAs generated with an anchor primer, associated with a universal sequence, were amplified with an arbitrary primer and a single fluorescently labeled primer.

Genome activation and developmental block in bovine embryos.

The ultimate goal of in vitro embryo culture systems is to perfectly mimic the condition of oocyte maturation, fertilization and embryo development. These systems are far more complex than standard in vitro cell culture because of the various environments through which the gametes and embryos pass during in vivo development. Improvement of the medium and other culture conditions has allowed for full development of a percentage of the fertilized oocytes but the great majority of bovine zygotes stop developing within a few cell cycles after initiating cleavage.