bruno and P-element transposition: positive regulator or cellular responder?
To determine whether bruno regulates P-element transposition or represents a tolerance factor, we compared P-element expression and excision rates between bruno mutants and wild-type, as well as between natural tolerant and sensitive alleles of bruno. If P-element transposition is independent of bruno, expression and excision should not differ between bruno genotypes. Our data suggest that P-element transcription does not differ between tolerant and sensitive alleles, consistent with bruno’s proposed role in tolerance. However, excision rates in bruno LOF mutants are greatly reduced, suggesting that bruno might influence germline loss by facilitating P-element excision. This function does not clearly align with established models of resistance and tolerance, but rather suggests bruno determines the permissivity of host cells to P-element transposition.