We used high-density oligonucleotide microarrays to analyse the genomes and meiotic expression patterns of two yeast strains, SK1 and W303, that display distinct kinetics and efficiencies of sporulation. Hybridization of genomic DNA to arrays revealed numerous gene deletions and polymorphisms in both backgrounds. The expression analysis yielded approximately 1,600 meiotically regulated genes in each strain, with a core set of approximately 60% displaying similar patterns in both strains. Most of these (95%) are MATa/MATalpha-dependent and are not similarly expressed in near-isogenic meiosis-deficient controls. The transcript profiles correlate with the distribution of defined meiotic promoter elements and with the time of known gene function.

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 f luorescently 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.The genome sequencing projects have generated and will continue to generate enormous amounts of sequence data. The genomes of Saccharomyces cerevisiae, Haemophilus influenzae (1), Mycoplasma genitalium (2), and Methanococcus jannischii (3) have been completely sequenced. Other model organisms have had substantial portions of their genomes sequenced as well including the nematode Caenorhabditis elegans (4) and the small flowering plant Arabidopsis thaliana (5). Given this everincreasing amount of sequence information, new strategies are necessary to efficiently pursue the next phase of the genome projects-the elucidation of gene expression patterns and gene product function on a whole genome scale.One important use of genome sequence data is to attempt to identify the functions of predicted ORFs within the genome. Many of the ORFs identified in the yeast genome sequence were not identified in decades of genetic studies and have no significant homology to previously identified sequences in the database. In addition, even in cases where ORFs have significant homology to sequences in the database, or have known sequence motifs (e.g., protein kinase), this is not sufficient to determine the actual biological role of the gene product. Experimental analysis must be performed to thoroughly understand the biological function of a given ORF's product. Model organisms, such as S. cerevisiae, will be extremely important in improving our understanding of other more complex and less manipulable organisms.To examine in detail the functional role of individual ORFs and relationships between genes at the expression level, this work describes the use of genome sequence information to study large numbers of genes efficiently and systematically. The procedure was as follows. (i) Software scripts scanned annotated sequence information from public databases for predicted ORFs. (ii) The start and stop position of each identified ORF was extracted automatically, along with the sequence data of the ORF and 200 bases flanking either side. (iii) These data were used to automatically select PCR primers that would amplify the ORF. (iv) The primer sequences were automatically input into the automated multip...

To examine the in vivo role(s) of type I interferons (IFNs) and to determine the role of a component of the type I IFN receptor (IFNAR1) in mediating responses to these IFNs, we generated mice with a null mutation (-/-) in the IFNAR1 gene. Despite compelling evidence for modulation of cell proliferation and differentiation by type I IFNs, there were no gross signs of abnormal fetal development or morphological changes in adult IFNAR1 -/-mice. However, abnormalities of hemopoietic cells were detected in IFNAR1 -/-mice. Elevated levels of myeloid lineage cells were detected in peripheral blood and bone marrow by staining with Mac-i and Gr-1 antibodies. Furthermore, bone marrow macrophages from IFNAR1 -/-mice showed abnormal responses to colony-stimulating factor 1 and lipopolysaccharide. IFNAR1 -/-mice were highly susceptible to viral infection: viral titers were undetected 24 hr after infection of IFNAR1 +/+ mice but were extremely high in organs of IFNAR1-/-mice, demonstrating that the type I IFN system is a major acute antiviral defence. In cell lines derived from IFNAR1 -/-mice, there was no signaling in response to IFN-a or -,B as measured by induction of 2'-5' oligoadenylate synthetase, antiviral, or antiproliferative responses. Importantly, these studies demonstrate that type I IFNs function in the development and responses of myeloid lineage cells, particularly macrophages, and that the IFNAR1 receptor component is essential for antiproliferative and antiviral responses to IFN-a and -1.