Plant & Animal Genome IX Conference

Poster: Sequencing & EST
P01_03.html

CHARACTERIZATION OF A NORMALIZED CDNA LIBRARY OF PIG OVARIAN FOLLICLES

University of Nebraska-Lincoln, Department of Animal Science, Lincoln, NE, 68583-0908, USA

Improvement of swine reproductive traits is of major importance to the pork industry. Over the past 20 years, we have developed highly unique lines of pigs that were selected 18 generations for components of litter size and differ by ~45% in ovulation rate and ~30% in litter size. Ovulation rate in the pig is determined by the dynamics of follicle development, which in turn is dictated by a balance between follicle recruitment, maturation, selection and atresia. The role of several genes expressed in the ovaries in this process has been described, but studies utilizing large-scale genomic approaches have yet to be conducted. We are developing the resources necessary for conducting RNA expression profile studies, with DNA microarrays, of ovarian follicle development in pigs. Gilts from high (n=7) and low (n=7) UNL ovulation rate selection lines were injected with PGF2a on day 13 (d0) of the estrous cycle. Ovaries were harvested by ovariectomy on d0-6, and follicles were dissected. mRNA isolated from 83 ovarian follicles, ranging from 2.0 to 10.0 mm in diameter, was used to construct a cDNA library (5x10⁶cfu) with average insert size of ~1.2kb. This cDNA library was normalized and is being sequence-characterized, with a goal of generating 3,000 unique clones. The sequences are being processed, compared to public databases and annotated. Clones containing unique sequences will be used for constructing a cDNA microarray for conducting RNA expression studies to elucidate processes regulating follicle developmental dynamics in the pig, and to discover the genomic basis for response to selection for enhanced reproduction.