Figure 4. GSC nucleolar morphology and rDNA copy number decrease is heritable.

(A) Scheme for aging of flies and collection of F₁ progeny from old parents. (B) rDNA quantification from testes by qPCR in P₀ at 0 and 40 days, and F₁ at 0 days. Mean ±SD (p-value *≤0.05, t-test). (C) GSC nucleolar morphology in young P₀, old P₀ and young F₁, as a percentage of total GSCs scored (n, number of GSCs scored). p-values from chi-squared test are shown. (D) Nucleolar dominance assessed by SNP in situ in GSCs from young P₀, old P₀ and young F₁ (n, number of GSCs scored). Mean ±SD. p-value of t-test is shown. Note that ‘X-only’ rRNA transcription was never observed. (E) Y:X signal intensity ratio for the 18S rDNA and 240-IGS in mitotic germ cells comparing day 0 P₀ Y and day 0 F₁ Y (from day 40 father). Day 0 vs. day 40 fathers (P₀) were mated to day 0 old females to yield P₀ Y/X vs. F₁ Y/X ratio, where X comes from the same source (day 0 yw female). Bracket indicates mean ±SD. p-values from Student’s t-test is shown. (F) Effect of X and Y chromosome inheritance from young vs. old parents on nucleolar morphology, as a percentage of total GSCs scored (n, number of GSCs scored). P-value from chi-squared test is shown.