|Roberts, Andrew - Andy|
Submitted to: Society for the Study of Reproduction Annual Meeting
Publication Type: Abstract only
Publication Acceptance Date: 5/14/2004
Publication Date: 6/1/2004
Citation: Turzillo, A.M., Moore, H.C., Rajapaksa, K.S., Greer, K.A., Hoying, J.B., Collier, R.J., Roberts, A.J. 2004. Gene expression profiling in pituitary glands of cows during the preovulatory period using bovine specific cdna microarrays. Society for the Study of Reproduction Annual Meeting Proceedings Abstract 368. Interpretive Summary:
Technical Abstract: During the bovine preovulatory period increasing circulating concentrations of LH are accompanied by decreasing concentrations of FSH. Endocrine factors regulating these secretory patterns have been characterized, but molecular mechanisms that result in differential gonadotropin secretion are not well understood. As a first step toward understanding gene networks that control dynamic secretory patterns displayed by gonadotropes, bovine-specific cDNA microarrays were used to profile pituitary gene expression patterns during the preovulatory period. Anterior pituitary glands were collected from cows at 0 (n=4), 24 (n=5), 48 (n=5) and 72 (n=5) h after a luteolytic injection of PGF2' on d 18 of the estrous cycle. Total RNA was isolated from pituitary glands and pools of RNA (2 or 3 samples/pool) were made for each time point. Each RNA pool was amplified, reverse transcribed into cDNA modified to contain amino allyl-UTP, labeled with dye (Alexa Flour 555 & 647), and hybridized to custom printed arrays containing 4600 expressed sequence tags (ESTs) derived from bovine mammary, pituitary and gastrointestinal tissues. Each pool was labeled twice with each dye and compared to 4 pools from different time points for a total of 16 hybridizations. A gene-by-gene ANOVA was performed that accounted for contributions of array, dye and sample to measured intensities. Genes were identified as differentially expressed if the P value for the sample term in the ANOVA was < 0.05 and the calculated fold change between any 2 samples was > 1.5. A total of 511 ESTs exhibited differential expression of which 171 have known identities. Of the 10 ESTs that yielded the greatest variation in expression among the 4 time points, 4 had known identities: cAMP-dependent protein kinase type 1 regulatory subunit, gastrin-releasing peptide, corticotrophin-beta-lipotropin precursor, and immunoglobulin lambda chain (V region). We conclude that this custom, bovine-specific array is an efficacious tool for identifying novel genes and characterizing gene expression patterns in the bovine pituitary gland. Further characterization of these genes will help elucidate genetic mechanisms that mediate communication between extrapituitary signals and intrapituitary gene networks, thus resulting in divergent synthesis and secretion of LH and FSH.