Post Transcriptional Gene Silencing in Plants (PTGS) - Eurasnet.info

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POST - TRANSCRIPTIONALGENE SILENCING -PTGS„RNA interference“ RNAi, a phenomenon in C. elegansand Drosophila for silencing of gene expression through asignal induced by double stranded RNA (dsRNA)C. elegans: injection of dsRNA: corresponding gene productdisapears in the somatic cells, also in F1 generation.However, F2 normal phenotyp, no mutation, no sequencedifference: is post-transcriptional because only exonsequences show RNAi. In polycistronic pre-mRNAs only thesequences of the initial dsRNA are silenced. RNAdegradation is at the level of nucleus and cytoplasm.WHAT HAPPENS? WHY is DEGRADATIONtransmissible through the whole organism??
PTGS: siRNAsPlants: 1999: small RNAs of 21- 25 nt were detected which correspondedto the silenced gene, but only detectable in plants which were silenced. Alsofor viral sequences(Hamilton and Baulcombe, Science, 286, 950).Drosophila: induced silencing of a gene with a dsRNA, cell extract hadnuclease activity which was sequence specific: partial purified nucleasecontained sequence specific 21-25 mers.Cell extract could be induced with dsRNA to process the dsRNA into21-23 nt RNA (dsRNA nuclease). Addition of mRNA resulted in degradationof sequences corresponding to the original dsRNA sequence: siRNA: small interfering RNAs: hallmark in RNA silencing
Page 2 and 3: POST TRANSCRIPTIONALGENE SILENCING
Page 4 and 5: PTGS can also be induced by homolog
Page 7 and 8: Cross protection: for several virus
Page 9: Fire, A. TIGS, 15, 358 (1999)
Page 13 and 14: An integrated model for RNAi and PT
Page 15 and 16: Systemic silencing: mobile signalsi
Page 17 and 18: Intercellular transport of TMV RNA?
Page 20 and 21: Viruses fight back: suppressors of
Page 22 and 23: RNA-based silencing strategies in p
Page 24 and 25: General pathway of RNAi in vitroRNA
Page 26 and 27: siRNA asymmetry, dsRNA processing a
Page 28: RISC Assembly in Drosophila

Post Transcriptional Gene Silencing in Plants (PTGS) - Eurasnet.info

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