LAUSR

that cysts may be differentiating prematurely. The pre-meiotic Impα1 mutant phenotype can be phenocopied by germline expression of a dominant-negative Impα1 protein that lacks the Impβ binding domain. We identified genes known to be expressed in the testis that produce proteins containing a consensus nuclear localisation sequence and screened for the ability of the dominant-negative allele to prevent protein transport into spermatogonial nuclei. From this screen we identified CycH and CG12909 as potential targets of IMPα1. Germline specific knockdown of CG12909 produces a phenotype similar to that of Impα1 alleles. The mammalian ortholog of CG12909, LYAR, has been associated with recruitment of the methyltransferase PRMT5 to specific regions of chromatin and symmetric dimethylation of histone H4 Arg3.