A SURVEY OF THE GOAT GENOME TRANSCRIBED IN THE LACTATING MAMMARY-GLAND

To fulfill its primary function, which is to synthesize milk during th e course of lactation, the mammary gland requires efficient transcript ional, translational, and secretory machineries involving multiple gen es among which promising candidates underlying the genetic variation o f milk production have to be found. With the aim of providing a first transcriptional profile of lactating mammary tissue, a non-normalized cDNA library has been constructed from the udder of a lactating goat. After having discarded cDNA clones encoding the major milk proteins th e rapid characterization of genes expressed in this tissue, by automat ed partial cDNA sequencing, was used to analyze a total of 435 cDNA cl ones. Examination of the Expressed Sequence Tags (ESTs) for similariti es with sequence databases identified 234 cDNAs corresponding to 140 u nique genes or proteins. Eighty-three clones, not similar to any curre nt database entries, representing 77 novel sequences unrelated to prev iously described genes, were thus identified. Tissue specificity and r elative abundance of 18 of these 77 unidentified clones were examined by dot blot and RT-PCR experiments. Sequence data were subsequently us ed to assign six genes of unknown localization in the bovine genome, t o synteny groups by use of bovine-hamster cell hybrids and PCR.