Construction of a bovine yeast artificial chromosome (YAC) library

We have constructed a bovine yeast artificial chromosome (YAC) library to provide a common resource for bovine genome research. We used leukocytes of a Japanese black bull (Bos taurus) as the DNA source, AB1380 for the yeast host, and pYAC4 for the vector. The library consists of 24,576 clones arranged in 256 96-well microtiter plates. An average insert size estimated from the analysis of 251 randomly selected clones was 480 kb. The rate of chimeric YACs evaluated by fluorescence in situ hybridization (FISH) analysis of 44 randomly selected clones was 36.4%. To estimate the number of genome equivalents, PCR-based screening was performed with 48 primer pairs and isolated 3.2 clones on average. In order to provide broad access for the scientific community, this library has been incorporated into the Reference Library system which provides high density filters for colony hybridization screening and a common database of the library.