Plant & Animal Genome VII Conference Plant & Animal Genome VII Conference
P67
Transcript profiling was used to identify additional genes involved in lactation and dry off in the bovine mammary gland (MG). Nylon arrays and human microarray (UniGEM, Synteni, Palo Alto, CA) were used to determine the genes expressed during lactation, involution and following bST treatment in the MG. Nylon arrays were generated from bovine mammary EST cDNA libraries; about 400 unique singleton ESTs were arrayed on nylon filters. The relative expression levels were determined by hybridization with 32P-labeled first strand cDNA probe prepared from mammary tissues at different stages of lactation. Transcript profiling with human microarrays identified a set of human gene homologues that are regulated during the processes of lactation and involution. In addition, two subtraction libraries were generated using RNA from lactating and fully involuted mammary glands. Libraries were generated by subtraction of involuted gland cDNA from lactating gland cDNA and by subtraction of lactating gland cDNA from involuted gland cDNA using ClonTech's PCR select method. About 500 singletons were identified from each subtraction. First subtraction identified genes expressed in the lactating gland while the second identified genes expressed in the involuted MG. Both transcript profiling and subtraction cDNA approaches identified many of the same genes expressed specifically either in lactating gland or involuted gland. Genes identified by these approaches will be selected for mapping using a bovine radiation hybrid panel and human-bovine comparative mapping. In addition, gene expression profiles of the MG during lactation and involution will facilitate our understanding the control of these processes.