Figure 4. Primordial germ cells (PGCs) reduce uaDf5 heteroplasmy independently of lobe cannibalism.

(A) Schematic of C. elegans mitochondrial DNA (mtDNA); genes are indicated with colored arrows and the region deleted in uaDf5 is shown with a red bar. (B) Quantification of uaDf5 heteroplasmy in whole embryos, sorted PGCs or germline stem cells (GSCs), or whole adults at the indicated stages. (C) Quantification of mtDNA copy number in PGCs of uaDf5 and nop-1; uaDf5 mutants. (D) Quantification of uaDf5 heteroplasmy in nop-1; uaDf5 mutant PGCs. (E) Data from (B and D) presented as change in heteroplasmy shift from embryonic to L1 PGCs. Data in graphs: small dots are three technical replicates of droplet digital PCR (ddPCR) quantification from each of three color-coded biological replicates; the technical replicate mean from each experiment is shown as a larger circle, the mean of means as a horizontal line, and the SEM as error bars. n.s., not significant (p>0.05), *p≤0.05, **p≤0.01, ***p≤0.001, paired (B, D) and unpaired (B, C, E) two-tailed Student’s t-test.

Figure 4—figure supplement 1. Droplet digital PCR (ddPCR) primers, detection of mitochondrial DNA (mtDNA) deletions, and mptDf2 inheritance in primordial germ cells (PGCs).

(A) Schematic of C. elegans mtDNA showing mtDNA deletions uaDf5 and mptDf2, as well as color-coded primer pairs for detecting wild-type and mutant mtDNA by ddPCR. Blue primers, wild-type mtDNA (uaDf5 experiments); black primers, uaDf5 mtDNA; purple primers, wild-type mtDNA (mptDf2 experiments); and green primers, mptDf2 mtDNA. (B) Representative ddPCR plot for quantifying uaDf5 and WT mtDNA copy number in sorted PGC lysates. (C) Representative ddPCR plot for quantifying mptDf2 and WT mtDNA copy number in sorted PGC lysates. Positive droplets (blue dots), negative droplets (black dots), and the threshold for positive droplets (magenta line) are shown. (D) The mtDNA copy number in mptDf2 embryonic and L1 PGCs. (E) The proportion of mptDf2 embryonic PGC mtDNAs inherited by L1 PGCs compared to wild type (from data in D and Figure 2B). (F) The percentage of mptDf2 heteroplasmy in embryonic and L1 PGCs. Data in graphs: small dots are three technical replicates of ddPCR quantification from each of three color-coded biological replicates; the technical replicate mean from each experiment is shown as a larger circle, the mean of means as a horizontal line, and the SEM as error bars. n.s., not significant (p>0.05), **p≤0.01, ***p≤0.001 paired (F) and unpaired (E,D) two-tailed Student’s t-test.