A screen for genes required for meiosis and spore formation based on whole-genome expression

Background: Meiosis is the process by which gametes are generated with half the ploidy of somatic cells. This reduction is achieved by three major dif ferences in chromosome behavior during meiosis as compared to mitosis: the production of chiasmata by recombination, the protection of centromere-prox imal sister chromatid cohesion, and the monoorientation of sister kinetocho res during meiosis I, Mistakes in any of these processes lead to chromosome missegregation, Results: To identify genes involved in meiotic chromosome behavior in Sacch aromyces cerevisiae, we deleted 301 open reading frames (ORFs) which are pr eferentially expressed in meiotic cells according to microarray gene expres sion data, To facilitate the detection of chromosome missegregation mutants , chromosome V of the parental strain was marked by GFP, Thirty-three ORFs were required for the formation of wild-type asci, eight of which were need ed for proper chromosome segregation. One of these (MAM1) is essential for the monoorientation of sister kinetochores during meiosis I, Two genes (MND 1 and MND2) are implicated in the recombination process and another two (SM A1 and SMA2) in prospore membrane formation. Conclusions: Reverse genetics using gene expression data is an effective me thod for identifying new genes involved in specific cellular processes.