Fig. 1

Heterogeneity inside cluster 1A. A Subtelomeric cluster 1A on the X chromosome in the P-1152 strain composed of several repeats (n) containing solo LTRs of INV-4 (gray), T1 (blue), T2 (pink), and T4 (yellow) domains also found in autosomal subtelomeric piRNA clusters and the T3 domain (0.9 kb) found only in cluster 1A (green). One of the repeats contains the P(lArB) transgenes (18 kb) (asterisks). B The P(lArB) transgene includes the 5′ and 3′ P-derived sequences, a plasmid sequence, rosy, Adh, lacZ (under the control of the P promoter), and the two transcriptional terminators (tCG and tHs). Black arrows represent the sense of transcription. C Paternal (PI) and maternal (MI) inheritances of cluster 1A were obtained by two reciprocal crosses between P-1152 and Canton strains. The maternal alleles are above the fraction. P-1152 carries P(lArB) and T3 in cluster 1A (“P(larB); T3 + ”), absent in Canton (“Δ-1A”). D Ovarian lacZ repression in the PI and MI P(lArB) lineages. Values represent the mean of four sublines with standard deviation. E Experimental design showing regions complementary to maternal piRNAs (small black lines) in G1. Maternal piRNAs in PI are produced by autosomal subtelomeres. Below are the size distributions of normalized 20–29-nt counts and the relative frequency (z-score) of overlapping sense-antisense small RNA pairs in the subsets of 23–29-nt RNAs matching P(lArB) and T3, showing enrichment of 10 nucleotides overlaps. The sense piRNAs are in red, and the antisense are in blue. F, G Normalized 23–29-nt reads mapping to P(lArB) (F) and T3 (G) of the MI H and PI D sublines. The percentage of 23–29-nt P(lArB) and T3 RNAs beginning with a 5′ uridine (1U bias) and characteristic of piRNAs are indicated for G4. Note that P(lArB) (18 kb), X subtelomeric repeat (1.8 kb), and T3 (0.9 kb) are not drawn to scale