The piRNA pathway is a highly conserved mechanism to repress transposon activation in the germline in Drosophila and mammals. This pathway starts from transcribing piRNA clusters to generate long piRNA precursors. The majority of piRNA clusters lack conventional promoters. and utilize heterochromatin- and HP1D/Rhino-dependent noncanonical mechanisms for transcription. https://www.roneverhart.com/1619PA8038-Bosch-Table-Saw-Motor-Housing-4000-4100-Replaces-2610996864/