The spr alleles pf52 and by146 affect NMD. A) The genetic position of spr-8(pf52). The genetic position of pf52 is shown with the position of classical genetic markers in blue and Single Nucleotide Polymorphisms (SNPs) in red used to position pf52. smg-6 is also found within the minimal region for spr-8 B) The results of the rpl-12 test for several strains. A 2% agarose gel with PCR fragments from rpl-12 is shown. N2 controls only have the smaller product while smg-5(r860) animals show both. The weak spr alleles pf52 and by146 have defects in NMD, while pf14, pf21, pf71, pf126 and ok1537 have retained NMD. C) An alignment of the PINc domain of SMG-6 from Homo sapiens (Hsa accession # NP_060045), Brugia malayi (Bma accession # EDP30730.1) and Caenorhabditis elegans (Cel accession # NP_497566.3). The sequences were aligned by ClustalW and analyzed by Boxshade. Identical amino acids are shaded in black while similar amino acids are shaded in grey. The three catalytic aspartates are denoted by a * above the sequence. The position of the pf52 G→D mutation is shown by a D above the sequence just after the last catalytic aspartate.