At present, the yeast genetic collection at the ATCC contains 1,276 Yeast Genetic Stock Center (YGSC) strains of Saccharomyces (S.) cerevisiae, approximately 20,000 Saccharomyces Genome Deletion Project (SGDP) strains, over 1,400 ATCC S. cerevisiae strains, and 400 other yeasts, representing 13 genera and 21 species. Yeast-associated resources at the ATCC include 1,888 Yeast Artificial Chromosome (YAC) clones, 400 vectors, and 22 DNA libraries. The application seeks the continued support of this national YGRRC funded by the National Center for Research Resources (NCRR)/National Institutes of Health (NIH) (1P40RR13278). The Specific Aims of this proposed project include the following: 1) authenticate, cryopreserve, and distribute 1,200 well-defined and characterized S. cerevisiae genetic stocks. This number includes 290 strains from the Nasmyth Laboratory (meiosis-sporulation collection), 280 strains from the Holm Laboratory (DNA replication collection), 130 strains from the Sachs Laboratory (mRNA study collection), and 500 SGDP strains (requested by scientists in single culture format); 2) improve the authentication of yeast genetic strains arrayed in 96-well and other high throughout formats to ensure the quality of the investigators' genetic stock products. This will be accomplished by conducting morphological and functional studies, testing polymerase chain reaction (PCR) products, and direct genomic DNA sequencing of randomly selected samples from arrayed plates; 3) prepare for distribution 1,200 YGSC strains, originally from the University of California at Berkeley (UCB), in 96-well format, now available only in single culture format; 4) develop new cryopreservation protocols for genetic stock to minimize genetic drift and provide more reliable delivery service by shipping cultures frozen in dry ice instead of as test tube cultures; and 5) increase user awareness of the YGRRC collection via printed and Web-based communications, as well as presentations at scientific conferences.