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SUMMARY:A small RNA-based innate immune system guards the integrity of ger
 m cell genomes - Professor Greg Hannon\, Cancer Research UK Cambridge Inst
 itute 
DTSTART:20200116T161500Z
DTEND:20200116T171500Z
UID:TALK132145@talks.cam.ac.uk
CONTACT:Caroline Newnham
DESCRIPTION:PIWI-family proteins and their associated small RNAs (piRNAs) 
 act in an evolutionarily conserved innate immune mechanism that provides a
 n essential protection for germ cell genomes against the activity of mobil
 e genetic elements. piRNA populations comprise a molecular definition of t
 ransposons that permits them to be distinguished from host genes and selec
 tively silenced. piRNAs can be generated in two distinct ways. Primary piR
 NAs emanate from discrete genomic loci\, termed piRNA clusters\, and appea
 r to be derived from long\, single-stranded precursors. The biogenesis of 
 primary piRNAs involves at least two nucleolytic steps. Zucchini cleaves p
 iRNA cluster transcripts to generate monophosphorylated piRNA 5’ ends. p
 iRNA 3’ ends are likely formed by exonucleolytic trimming\, after a piRN
 A precursor is loaded into its PIWI partner. Secondary piRNAs arise during
  the adaptive ping-pong cycle\, with their 5’ termini being formed by th
 e activity of PIWIs themselves. At least in Drosophila\, piRNAs are matern
 ally deposited and transmit an epigenetic signal essential for the effecti
 ve control of at least some transposable elements. Our continuing efforts 
 combine genetics\, biochemistry\, structural biology\, and evolutionary an
 d computational approaches to understand how the piRNA pathway effectively
  discriminates self from non-self at the genomic level.
LOCATION:Biffen Lecture Theatre\, Department of Genetics\, Downing Site
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