Fig. 4: Maternal slow-1 transcripts inhibit piRNA-mediated repression.
From: Selfish conflict underlies RNA-mediated parent-of-origin effects
a, Top, in the slow-1(fs)/grow-1(−) double mutant NIL strain, both slow-1 and grow-1 carry frameshift (fs) mutations. Bottom, TA activity is observed regardless of maternal or paternal inheritance (M, n = 31; P, n = 24; two-sided Fisher’s exact test; P = 0.43; data are mean ± 95% confidence interval). b, Top, in the slow-1(Δ)/grow-1(−) mutant NIL strain, the full slow-1 gene (including coding sequence and UTR) is deleted, and grow-1 carries a frameshift mutation. Bottom, slow-1/grow-1 is only active when maternally inherited (M, n = 18; P, n = 25; two-sided Fisher’s exact test; P < 0.0001; data are mean ± 95% confidence interval). c, In vitro transcribed slow-1 RNA with a mutated start codon was injected in the gonad of slow-1(Δ)/grow-1(−) double mutant NILs and later crossed to NIL males. Approximately half of their Δ/Δ F2 progeny were delayed. Control mothers were injected with DEPC H2O (slow-1 RNA, n = 128; control, n = 62; two-sided Fisher’s exact test P < 0.0001; data are mean ± 95% confidence interval). d, Reciprocal crosses between worms carrying an N-terminally tagged mScarlet::slow-1 and EG6180 (top and middle crosses). Maternal mScarlet expression (rps-20p::mScarlet::rps-20 3′ UTR chromosome V) licenses paternal mScarlet::slow-1 (bottom cross). Maternal mScarlet::slow-1; n = 23; paternal maternal mScarlet::slow-1, n = 31; maternal mScarlet, paternal maternal mScarlet::slow-1, n = 38; two-sided Fisher’s exact test; P < 0.0001; data are mean ± 95% confidence interval. e, Schematic of the C. elegans piRNA pathway. Target recognition and secondary sRNA amplification depend on the target mRNA, whereas epigenetic repression depends on complementarity to the nascent transcript of the target. f, Schematic of the mScarlet::SL2::slow-1 operon. The operon is transcribed as a single polycistronic transcript and later trans-spliced into two independent mRNA transcripts. Licensing could counter piRNA-mediated repression either during target recognition (mRNA) or epigenetic repression (nascent transcript). snRNP, small nuclear ribonucleoprotein particle. g, Reciprocal crosses between worms carrying the mScarlet::SL2::slow-1 operon and EG6180 (top and middle crosses). Maternal mScarlet expression does not license a paternally inherited mScarlet::SL2::slow-1 (bottom cross). Maternal mScarlet::SL2::slow-1, n = 32; paternal mScarlet::SL2::slow-1, n = 49; maternal mScarlet, paternal mScarlet::SL2::slow-1, n = 37; two-sided Fisher’s exact test; ****P < 0.0001; data are mean ± 95% confidence interval.
