Many aspects of meiotic entry in male Drosophila are controlled by the activity of the meiotic specific cdc25 homologue twine, a protein tyrosine phosphatase that activates p34cdc2. Mutations in twine and its translational regulators boule and off-schedule prevent meiotic entry. A second G2-M translational regulatory step occurs after twine expression, and is controlled by the Cytoplasmic Polyadenylation Element Binding (CPEB) protein orb2. Similarly, mutations in orb2 result in a prolonged G2-M arrest. To identify other genes responsible for regulating the G2-M transition, we have identified male sterile mutations that cause a similar meiotic phenotype. Seven chromosome 2 and eight chromosome 3 mutations were identified from a collection of previously identified male sterile mutations (Wakimoto BT, Lindsley DL and Herrera C., 2004). These represent thirteen complementation groups: twelve unique genes and one complementation group consisting of three mutations that fail to complement the amorphic twineHB5 allele. We have taken a bioinformatics approach to confirm the 3 new twine alleles and identify the mutated genes in the 12 remaining lines. We created strains bearing four mutations each (i. e. transheterozygous for mutations on both chromosome 2 and 3), and performed whole genome sequencing at 11x coverage to identify the causative mutations. We identified new missense mutations in twine for each of the three non-complementing mutations. Towards identify the unknown genes, we have filtered variants in the genome sequence data by chromosome and eliminated variants shared between lines. We are presently completing recombination mapping with respect to dominant mutations to further delimit variants to candidate genes.