Yeast microarrays for genome wide parallel genetic and gene expression analysis

We have developed high-density DNA microarrays of yeast ORFs. These microarrays can monitor hybridization to ORFs for applications such as quantitative differential gene expression analysis and screening for sequence polymorphisms. Automated scripts retrieved sequence information from public databases to locate predicted ORFs and select appropriate primers for amplification. The primers were used to amplify yeast ORFs in 96-well plates, and the resulting products were arrayed using an automated micro arraying device. Arrays containing up to 2,479 yeast ORFs were printed on a single slide. The hybridization of fluorescently labeled samples to the array were detected and quantitated with a laser confocal scanning microscope. Applications of the microarrays are shown for genetic and gene expression analysis at the whole genome level.

Mapping expressed sequence tag sites on yeast artificial chromosome clones of Arabidopsis thaliana DNA

We describe a method for efficient parallel mapping of expressed sequence tag (EST) sites onto yeast artificial chromosome (YAC) clones. The strategy involves an initial YAC clone pooling scheme that minimizes the number of required PCR amplifications. This is followed by parallel analysis of PCR amplicons of EST sequences. Using this method, we have screened 600 EST sites in combinatorial pools of 3449 YAC clones that contain Arabidopsis thaliana DNA inserts. The presence of these genes on YACs was detected by amplifying EST sequences with PCR and analyzing the reaction products by agarose gel electrophoresis. Of the 600 ESTs, 271 were found to map to individual YACs. Software tools are presented that allow for the automated analysis of this electrophoresis data. Suggestions for the scale-up of this method to map large genomes are discussed.