title: DNA microarray analyses reveal a post-irradiation differential time-dependent gene expression profile in yeast cells exposed to X-rays and gamma-rays.
abstract: Ionizing radiation (IR) is the most enigmatic of genotoxic stress inducers in our environment that has been around from the eons of time. IR is generally considered harmful, and has been the subject of numerous studies, mostly looking at the DNA damaging effects in cells and the repair mechanisms therein. Moreover, few studies have focused on large-scale identification of cellular responses to IR, and to this end, we describe here an initial study on the transcriptional responses of the unicellular genome model, yeast (Saccharomyces cerevisiae strain S288C), by cDNA microarray. The effect of two different IR, X-rays, and gamma (gamma)-rays, was investigated by irradiating the yeast cells cultured in YPD medium with 50 Gy doses of X- and gamma-rays, followed by resuspension of the cells in YPD for time-course experiments. The samples were collected for microarray analysis at 20, 40, and 80 min after irradiation. Microarray analysis revealed a time-course transcriptional profile of changed gene expressions. Up-regulated genes belonged to the functional categories mainly related to cell cycle and DNA processing, cell rescue defense and virulence, protein and cell fate, and metabolism (X- and gamma-rays). Similarly, for X- and gamma-rays, the down-regulated genes belonged to mostly transcription and protein synthesis, cell cycle and DNA processing, control of cellular organization, cell fate, and C-compound and carbohydrate metabolism categories, respectively. This study provides for the first time a snapshot of the genome-wide mRNA expression profiles in X- and gamma-ray post-irradiated yeast cells and comparatively interprets/discusses the changed gene functional categories as effects of these two radiations vis-à-vis their energy levels.
authors.affiliation: Laboratory of Environmental Biology, Department of Preventive Medicine, Hokkaido University School of Medicine, Sapporo 060-8638, Japan.
authors.forename: Shinzo
authors.initials: S
authors.lastname: Kimura
authors.forename: Emi
authors.initials: E
authors.lastname: Ishidou
authors.forename: Sakiko
authors.initials: S
authors.lastname: Kurita
authors.forename: Yoshiteru
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Junko
authors.initials: J
authors.lastname: Shibato
authors.forename: Randeep
authors.initials: R
authors.lastname: Rakwal
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Iwahashi
mesh_terms: D015536:Down-Regulation / Q000528:radiation effects; D005720:Gamma Rays; D020869:Gene Expression Profiling; D005800:Genes, Fungal / Q000235:genetics / Q000528:radiation effects*; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000528:radiation effects*; D013997:Time Factors; D015854:Up-Regulation / Q000528:radiation effects; D014965:X-Rays