Gene expression profile in juvenile Spo11 knockout testes

Spo11, a meiosis-specific protein, introduces double strand breaks on chromosomes and initiates meiotic recombination in a wide variety of organisms. Mouse null Spo11 spermatocytes fail to synapse chromosomes and to progress beyond zygotene stage of meiosis. We analyzed gene expression profiles in Spo11-/- adult and juvenile wild type testis to determine genes expressed in different stages of meiosis and spermatogenesis. These genes were characterized using Gene Ontology. To focus on genes involved in meiosis we performed comparative gene expression analysis of Spo11 -/- and wild type testes from 12 and 15 day mice. We found that the knockout of Spo11 gene causes dramatic changes in the level of expression of genes that participate in meiotic recombination (Hop2, Brca2, Mnd1, FancG) and in the meiotic checkpoint (cyclin B2, Cks2) at 15 day, but does not affect genes encoding protein components of the synaptonemal complex. Finally, we uncovered unknown genes that are affected by disruption of the Spo11gene and therefore, may be specifically involved in meiosis and spermatogenesis. Keywords: repeat sample Microarray experiments were performed in quadruplicate with different mouse pairs from the same mouse litter. The chips were scanned using the GenePix 4000A scanner (Axon Instruments) and primary data were analyzed using the Genepix 3.0 software. Primary data were flagged using four default parameters set in the Genepix 3.0 program. For further analysis, the data were imported into Excel (Microsoft) and normalized by the Median Centering Method. We performed the statistical analysis using a modified t-test implemented in SAM software (Tusher et al., 2001). We defined differentially expressed genes at a 1% false discovery rate confidence level and a cutoff for differential expression equal to 1.5 for juvenile Spo11-/- microarray experiments