Fig. 1.

Putative Penelope siRNA is present in whole adults of strain 160, absent from strain 9, and maternally inherited in the nondysgenic cross. (A) Sequence organization of Penelope and location of the probe for siRNA. Black arrows indicate terminal repeats. RT, reverse transcriptase domain. (B) Northern analysis with 50 μg of total RNA from adults of strain 9 and 160, as well as dysgenic and nondysgenic progeny and sense and antisense orientations of the Penelope probe. 5S RNA is shown as a loading control, with a 10-bp RNA ladder shown on the side. Above the blots, we designate chromosomes as bars, with chromosomes from strain 160 in black and chromosomes from strain 9 in white. The pair of sex chromosomes, with the Y chromosome designated with a hooked bar, is shown above, and a representative pair of autosomes is shown below. Maternal cytoplasm is designated with an oval, with white and black indicating the presence or absence, respectively, of strain 160 chromosomes in the mother. Sense and antisense Penelope RNA between 20 and 30 nt is absent from strain 9 and present in strain 160. In the progeny, putative siRNA is present in males and females of the dysgenic (Dys) cross but only present in females of the nondysgenic (Ndys) crosses. (C) Northern analysis of 5 μg of enriched RNA from 0- to 2-h, nondysgenic and dysgenic embryos with 5S loading control. DNA oligos of 20, 24, and 28 nt with antisense and sense orientation to the Penelope probe were used as a polarity control. Small sense and antisense Penelope RNA is detectable in early embryos of the nondysgenic cross but not in those of the dysgenic cross. (D) RT-PCR for ftz expression in 0- to 2-h and 0- to 13-h nondysgenic embryos. Reverse transcriptase-negative controls (-) and rp49-positive controls (+) are shown. Lack of ftz expression in 0- to 2-h embryos indicates that genome-wide transcription has not yet been initiated in the nondysgenic embryos from C.