CRISPR/Cas9 engineered smg-4 null allele. smg-4(az152) allele is confirmed NMD-defective by both the presence of the protruding vulva phenotype and the accumulation of NMD-targeted isoforms. smg-4(az152) is easy to track in crosses by PCR and digestion with BstBI (see S1 text of Suzuki, et al. for sequence of allele) and essentially mimics ma116 in having a G->A mutation at the last base of intron 1. az152 also removes two bases of exon 2 and inserts 50nt in exon 2. Reference: Suzuki JMNGL, et al. PLoS Genet. 2022 Feb 10;18(2):e1010028. doi: 10.1371/journal.pgen.1010028. PMID: 35143478.

dxbp-1(az121) is a K23N mutation that promotes usage of introns starting in UU when the sequence GUU is present at the 5' end of the intron. az121 was initially identified as able to suppress uncoordination of unc-73(e936) by promoting a cryptic splice site that defines an intron beginning UU. smg-4 mutant background allows for high throughput sequencing to identify frame shifted transcripts since it can move the 5'ss over by 1nt. e936az30 has no phenotype on its own, but it offers two adjacent cryptic 5'ss separated by 1nt. Reference: Suzuki JMNGL, et al. PLoS Genet. 2022 Feb 10;18(2):e1010028. doi: 10.1371/journal.pgen.1010028. PMID: 35143478.

az52 is a CRISPR-engineered M107I missense allele of dxbp-1. az52 has no phenotype on its own, but suppresses unc-73(e936) and unc-73(az63) by promoting use of a cryptic splice site for an intron beginning with UU. smg-4(az152) provides an NMD deficient background allowing identification of out-of-frame mis-splicing in an RNA-seq experiment. Reference: Suzuki JMNGL, et al. PLoS Genet. 2022 Feb 10;18(2):e1010028. doi: 10.1371/journal.pgen.1010028. PMID: 35143478.