RNA interference (RNAi) is a mechanism for gene silencing by degrading unwanted mRNAs in the cytoplasm, initially discovered in plants and later in C. elegans. The process involves small interfering RNAs (siRNAs) that guide the RNA-induced silencing complex (RISC) to degrade target mRNAs, offering a powerful method to inhibit gene expression. RNAi is valuable for research and has potential applications in crop improvement and functional gene analysis.

1. RNA INTERFERENCE
TECHNOLOGY- GENE
SLIENCING
(Shooting down mRNA)
By-Somanath Baral
Roll No.-BY3416
M.Sc part I
sb000333@gmail.com

2. BackgroundBackground
What is it and its discovery?What is it and its discovery?
The mechanism and processThe mechanism and process
Advantages of RNAi mechanismAdvantages of RNAi mechanism
in cellin cell
ConclusionConclusion
RNAiRNAi

3. Transcription
Translation

4. Shooting mRNA means RNA interference
What is RNA interference?

5. --Gene “knockdown”
--A cellular mechanism that degrades
unwanted RNAs in the cytoplasm but not
in the nucleus.
--A way for the cell to defend itself.

7. Jorgensen 1990
van der Krol 1990
Gene injection (pigmentation
Enzyme-petunias)
Expectation: more red color
Co-suppression of transgene
and endogenous gene.
First discovered in plants
(R. Jorgensen, 1990)

8. RNAi discovered in C. elegans (first animal) while
attempting to use antisense RNA in vivo
Craig Mello Andrew Fire (2006 Nobel Prize in
Physiology & Medicine)
Control “sense” RNAs also produced suppression of
target gene!
sense RNAs were contaminated with dsRNA.
dsRNA was the suppressing agent.

9. RNA interference:
--A type of gene regulation
--Involve small RNA molecules
--Induce a double stranded RNA
The RNAi process

10. The mechanism of
small interfering RNAs (siRNAs)
What happens?
dsRNA is processed into shorter units
(siRNAs) that guide the targeted cleavage
of homologous RNA.

11. Step 1
• dsRNA is processed
into sense and
antisense RNAs
• 21-25 nucleotides in
length
• have 2-3 nt 3’
overhanging ends
• Done by Dicer (an
RNase III-type
enzyme)
Dicer cuts dsRNA into short
RNAs

12. Step 2
• The siRNAs associate
with RISC (RNA-
induced silencing
complex) and
unwind

13. Step 3
• the antisense siRNAs
act as guides for RISC
to associate with
complimentary single-
stranded mRNAs.

14. Step 4
• RISC cuts the mRNA
approximately in the
middle of the region
paired with the siRNA
• The mRNA is degraded
further

15. Advantages of RNAi
1. The most powerful way to inhibit
unwanted gene expression and
acquire info about the gene’s
function fast
2. Works in any cell/organism
3. Uses conserved endogenous
machinery
4. Potent at low concentrations
5. Highly specific.

17. conclusion
RNAi is a valuable research tool,both in self culture and
in living organism.
Most widely held view is that RNAi evolved to protect the
genome virus.
The genetic modifications of plant by different
approaches have a millstone among RNAi shows the
greater potentiality to for crop improvement to sustain
the production and productivity.

18. References
1. Textbook of Genetics by Ajoy Paul
2. Genetics by P.K.Gupta
3. Images from Google

19. THANK YOUTHANK YOU