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SUMMARY:Uniparental expression of PolIV-dependent siRNAs in developing end
 osperm of Arabidopsis - Becky Mosher
DTSTART:20100205T130000Z
DTEND:20100205T133000Z
UID:TALK22543@talks.cam.ac.uk
CONTACT:15560
DESCRIPTION:Most eukaryotes produce small RNA (sRNA) mediators of gene sil
 encing that bind to Argonaute proteins and guide them\, by base pairing\, 
 to an RNA target. MicroRNAs (miRNAs) that normally target messenger RNAs f
 or degradation or translational arrest are the best-understood class of sR
 NAs. However\, in Arabidopsis thaliana flowers\, miRNAs account for only 5
 % of the sRNA mass and less than 0.1% of the sequence complexity. The rema
 ining sRNAs form a complex population of more than 100\,000 different smal
 l interfering RNAs (siRNAs) transcribed from thousands of loci. The biogen
 esis of most of the siRNAs in Arabidopsis are dependent on RNA polymerase 
 IV (PolIV)\, a homologue of DNA-dependent RNA polymerase II. A subset of t
 hese PolIV-dependent (p4)-siRNAs are involved in stress responses\, and ot
 hers are associated with epigenetic modifications to DNA or chromatin\; ho
 wever\, the biological role is not known for most of them. Here we show th
 at the predominant phase of p4-siRNA accumulation is initiated in the mate
 rnal gametophyte and continues during seed development. Expression of p4-s
 iRNAs in developing endosperm is specifically from maternal chromosomes. O
 ur results provide the first evidence for a link between genomic imprintin
 g and RNA silencing in plants.
LOCATION:Department of Plant Sciences\, Large Lecture Theatre
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