Molecular mechanisms regulating bovine ovarian follicular selection.

Transcription profiling of ovarian follicles. Understanding the mechanisms by which a single follicle is selected for further ovulation is important to control fertility in mammals. However, development of new treatments is limited by our poor understanding of molecular mechanisms regulating follicular selection. Our hypothesis is that genes involved in the control of cell proliferation and apoptosis are differentially regulated during follicular selection. Our objective was to identify these new genes. Bovine follicles were collected and gene expression levels were measured using microarrays. First, follicles were allocated to three groups, according to the time spent from the initiation of follicular wave to surgery (24 H, 36 H, and 48-60 H). Fifty-seven genes are differentially expressed at a false discovery rate of 5%. These genes are involved in the control of lipid metabolism (P-value = 0.0005), cell proliferation (0.007), cell death (0.003), cell morphology (0.003), and immune response (0.003). Follicles were also grouped into four categories, according to the expected time of deviation (early deviation; 8 mm, mid-deviation; 8.5 mm, late deviation; 9 mm, dominant follicles; >or=10 mm). One hundred and twenty eight genes are differentially expressed between these four groups, including genes involved in cell proliferation (0.00002), cell death (0.0006), cell-to-cell signaling (0.003), cell morphology (0.003), lipid metabolism (0.0004), and immune response (0.00007). The expression levels of 10 genes were confirmed using quantitative real time PCR. As expected, we identified new differentially regulated genes involved in the control of cell growth and apoptosis. We also discovered a potential role for immune cells, and in particular macrophages, in follicular selection.

Determination of serologic and colostral response in late-gestation cows vaccinated with a Mycoplasma bovis bacterin.

OBJECTIVE: To determine whether vaccinating cows during late gestation against Mycoplasma bovis will result in adequate concentrations of M bovis-specific IgG(1) in serum, colostrum, and milk. ANIMALS: 78 dairy cows. PROCEDURES: Serum samples were obtained 60 and 39 days prior to expected parturition in vaccinated and control cows from a single herd. Serum and colostrum samples were also obtained at parturition. Milk samples were obtained 7 to 14 days after parturition. Samples were analyzed for anti-M bovis IgG(1) concentrations. RESULTS: Prior to vaccination, control and vaccinated cows had similar anti-M bovis IgG(1) concentrations. After initial vaccination and subsequent booster and at parturition, there was a significant difference between the 2 groups, with vaccinated cows having higher IgG concentrations. Colostrum from vaccinated cows had higher anti-M bovis IgG(1) concentrations, compared with control cows; however, IgG(1) concentrations in milk did not differ between the 2 groups. CONCLUSIONS AND CLINICAL RELEVANCE: Vaccination of late-gestation cows resulted in increased concentrations of anti-M bovis IgG(1) in colostrum. However, ingestion of colostrum by calves may not guarantee protection against M bovis infection.