ptl-1 mRNA is not expressed in ptl-1∷(ok621) null mutant worms. mRNA was extracted from mixed stage worms (wild type and ptl-1(ok621) homozygotes) using Invitrogen’s Microfast-track kit (Invitrogen, Inc.) and converted to cDNA using Invitrogen’s Superscript III (Invitrogen, Inc.). Lanes 1,2: cDNA from ptl-1(ok621) worms (1 µg, 0.5µg respectively); Lanes 3,4: cDNA from wild type worms (1 µg, 0.5µg); Lane 5: ptl-1(ok621) single worm genomic DNA amplified with two primers, one of which is within exon 2; Lane 6: wild type genomic DNA with the same two primers as Lane 6; Lane 7: ptl-1(ok621) genomic DNA with three primers, described in Materials and methods.