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Lecture 28

BIOL 202 Lecture Notes - Lecture 28: Dicer, Rna Interference, Transposase


Department
Biology (Sci)
Course Code
BIOL 202
Professor
David Hipfner
Lecture
28

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Regulation of TEs by the host
Hipfner Biol 202 1
One mechanism for silencing TEs identified in C. elegans
oRon Plasterk, late 1990’s
oIdentified 25 C. elegans
genes required for TE
“silencing”
oMany were components
of RNA interference
(RNAi) machinery

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RNA interference -
Post-transcriptional
gene silencing
Hipfner Biol 202 2
oBased on short (~21-25 nt)
RNAs derived from double-
stranded RNA precursors
ocleavage by Dicer
oSequence-specific silencing
of mRNAs by RNA/RISC
omicroRNA (miRNA) –
endogenous gene
osiRNA – foreign gene
(transgene, virus, TE)
RNAi-induced
silencing
complex

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A siRNA mechanism silences TEs
Hipfner Biol 202 3
o “Read-through”
transcription of TE
next to host gene
o antisense transcript
hybridizes with TE
mRNA (transposase,
pol) to create dsRNA
o leads to processing
by Dicer, incorporation
into RISC
o Targets TE
transcripts for gene
silencing
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