Construction and screening of the yeast deletion strain collection. (a) The cassette used consists of a kanamycin-resistance gene (KanMX4) flanked by two tags (also called barcodes), the UPTAG and the DOWNTAG, which are unique to each gene. The yeast DNA 5' and 3' to the barcodes is homologous to yeast DNA flanking the gene to be deleted. After homologous recombination, the gene is replaced by the cassette sequences, including the barcodes. (b) Screening the deletion strains for differences in fitness under selective conditions. Selection leads to an increase in the proportion of some strains in the culture and a decrease of others; these changes can be detected by probing a microarray containing the sequences complementary to the barcodes. A stronger signal, indicating a higher level of a barcode in the RNA extracted from the culture, shows strains that have increased in frequency after selection. Adapted with permission from .
Scherens and Goffeau Genome Biology 2004 5:229 doi:10.1186/gb-2004-5-7-229