Construct: Amino acid replacement: V77G. Amino acid replacement: I526V. Fragment carrying the BP1 P-element (deletion from nucleotides 578 to 684 compared to a full length P-element, in frame deletion of 35 amino acids) cloned from the Muller-5 Birmingham strain is fused to an Hsp70 promoter in sense orientation. Element also carried base substitutions as above.