pkEx170 [gpb-1(+) + rol-6(su1006)]. Rollers. Pick Rollers to maintain. NL361 is homozygous for the gpb-1 deletion allele pk44; this results in an L1 arrest if the larvae has maternally derived GPB-1 or in an early embryonic lethality if there is no maternally derived GPB-1 for the developing embryo. This phenotype is rescued by the extrachromosomal transgene which contains the WT gpb-1 gene.