Table 2. Comparison of piRNA length between D. virilis and D. melanogaster. Mode was the most common length class among small RNAs 23 to 30 nt, post adapter trimming and filtering against ncRNA, miRNA, miscRNA and tRNA. Only including one of each replicate library for the comparison (indicated with * for each library included), the difference in small RNA mode is significant (p < .01, t test among modes). § indicates a library generated by oxidation by sodium periodate.

Species	Sample	Tissue	Source	Small RNA mode
Drosophila virilis	Strain 160 (rep 1)	0-2 hr embryos	Erwin et al. [41]	26*
Drosophila virilis	Strain 160 (rep 2)	0-2 hr embryos	Erwin et al. [41]	26
Drosophila virilis	Strain 9 (rep 1)	0-2 hr embryos	Erwin et al. [41]	26*
Drosophila virilis	Strain 9 (rep 2)	0-2 hr embryos	Erwin et al. [41]	26
Drosophila virilis	wt	follicle cells	Chirn et al. [93]	27*
Drosophila virilis	wt (rep 1)	0-4 hr unfertilized embryos	Ninova et al.[96]	27*
Drosophila virilis	wt (rep 2)	0-4 hr unfertilized embryos	Ninova et al.[96]	27
Drosophila virilis	Strain 9	0-2 hr embryos	Rozhkov et al. [97]	26*
Drosophila melanogaster	Oregon-R	follicle cells	Chirn et al. [93]	26*
Drosophila melanogaster	wt (rep 1)	0-4 hr unfertilized embryos	Ninova et al.[96]	26*
Drosophila melanogaster	wt (rep 2)	0-4 hr unfertilized embryos	Ninova et al.[96]	26
Drosophila melanogaster	Ral 437	ovaries§	Song et al.[98]	26*
Drosophila melanogaster	Ral 375	ovaries§	Song et al.[98]	26*
Drosophila melanogaster	Ral 714	ovaries§	Song et al.[98]	25*
Drosophila melanogaster	Ral 707	ovaries§	Song et al.[98]	25*
Drosophila melanogaster	Ral 427	ovaries§	Song et al.[98]	25*
Drosophila melanogaster	Ral 313	ovaries§	Song et al.[98]	25*
Drosophila melanogaster	Ral 732	ovaries§	Song et al.[98]	25*
Drosophila melanogaster	Ral 391	ovaries§	Song et al.[98]	25*