leIs1 [pes-1::lacZ + rol-6(su1006)] V. Rollers. B-galactosidase expression begins in a subset of cells of the AB lineage which go on to produce muscle, nerve and hypodermal cells. B-galactosidase is also present within the D lineage until the cells move anteriorly to become body wall cells. Expression is also apparent in Z1 and Z4 which go on to form part of the somatic gonad. plasmid name: pUL#24C7. Plasmid backbone: pPD22.11. Partial Sau3A fragments cloned into BamH1 site of vector.