Dicer-Like
A RNA Helicase Gene Involved in
Gene Silencing
UCSF
Max Bachour
Jessica Chen
Chris McQuilkin
A RNA Helicase Gene Involved in Gene Silencing
• RNA helicase is an enzyme that unwinds
RNA and modifies its structure
• Involved in transcription, splicing,
translation, and gene silencing
A RNA Helicase Gene Involved in Gene Silencing
How does Dicer-Like Help with Gene
Silencing?
RNA interference
• Dicer and Dicer-Like (DCL) enzymes are
involved in RNA interference (RNAi)
• Nontranslated RNA fragments bind to
mRNA and prevent translation into a protein
Evolutionary Origins
• A defense system for eukaryotes against
double stranded viruses and transposons
What is Dicer’s role in RNAi?
• Activated by exogenous double-stranded
(ds) RNA
• miRNA (micro RNA)
-small, non-coding regions of double-stranded
(ds) RNA
21-22 nucleotides
What is Dicer’s role in RNAi?
• siRNA (small interfering RNA)
non-coding regions of dsRNA 20-25 nucleotides in
length
What Happened When the Dicer-Like Gene
Was Knocked-out?
Seed from a Wild Type Plant
Dicer-Like Mutants
Cone Shaped
Suspensor
Cone Shaped
Suspensor
How did the Dicer Knock-out Result in the
Cone Shape?
•Knocking-out the dicer gene keeps RNAi from forming
•This keeps certain genes in the seed from being
inhibited.
•The lack of inhibition caused the cells in the embryo to
multiply irregularly
Why did we knock-out dicer?
• Provided a positive control to compare to
our T-DNA knock-out line
• Made sure that negative results weren’t due
to technical failure
• Our main goal is to discover the function
genes in arabidopsis.