Submitted to: European Association of Animal Production Proceedings
Publication Type: Proceedings
Publication Acceptance Date: May 10, 2003
Publication Date: N/A
A series of complex physiological processes underlie bovine mammary gland development from embryogenesis through puberty, pregnancy, lactation, and involution. The involvement of hormones such as estrogen and progesterone in these processes has been demonstrated. However, the mechanisms that ultimately modulate gene expression patterns for mammary cell proliferation, differentiation or secretory activity are not well understood. For example, it was demonstrated that estrogen and progesterone receptor transcript expression is significantly down regulated during mid-gestation in pregnant heifers but not pregnant lactating cows. To better understand effects of hormone response on downstream regulation of gene expression, studies were initiated to survey the mammary gland transcriptome. First, over 25,000 expressed sequence tags were characterized from a normalized cDNA library encompassing all the major physiological processes of the mammary gland. These sequence data and corresponding cDNA clones have been made freely available for all researchers. After testing several different platforms for transcript profiling, a nylon-based microarray containing reporters corresponding to more than 5,000 transcripts expressed in the mammary gland was developed. This resource is being used to evaluate effects on the mammary transcriptome of treatments that influence mammary development and lactation persistency. Significant differences in expression are being validated by quantitative real-time RT-PCR and immunohistochemistry or in situ hybridization.