The document outlines the composition and types of nucleic acids, including DNA and RNA, along with their functions in genetic material storage and transfer. It also describes techniques for demonstrating nucleic acids in medical diagnostics, highlighting various staining methods and their principles. Additionally, it covers enzymatic and chemical extraction methods for nucleic acids, underscoring the importance of these techniques in laboratory settings.

1. Demonstration of
nucleic acids
By: Omnia Elamin

2. Objectives :
Define the nucleic acid and
describe its composition.
0
1
Describe the diagnostic
application for the demonstration
of the nucleic acid.
0
2
List the methods for the
demonstration and describe their
principles.
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3
Define the enzymatic extraction
and describe its function
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4

3. Composition
of nucleic
acids:
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-Linear polymers of nucleotides.
-Each nucleotide consists of 3
components:
1- nitrogenous base.
2- pentose sugar.
3- phosphate group.

4. Types of nucleic acid
Double stranded,
helical,polymers
of
deoxyribonucleoti
des found in the
nucleus of the
cell.
- Function:
storage of the
genetic material.
DNA
single stranded,
nonhelical, polymers
of ribonucleotides
found in the nucleus
and cytoplasm of the
cell.
-function: to transfer
the genetic
information from
nucleus to
cytoplasm for
protein synthesis.
RNA
Deoxyribonucleic
acid
Ribonucleic
acid

5. Demonstration
of the nucliec
acid:

6. commonly used medical process in
the
medical diagnosis of tumors
in which a dye color is
applied on the sample tissues to
locate the diseased or tumorous cells
or other pathological cell
Why do we demonstrate the
nucleic acids?

7. Fixation
- Pathologic diagnosis requires tissue fixation for histologic
and immunohistologic analysis, and formalin is routinely
used for
this.
- In general terms, the nucleic acids are best preserved
in alcoholic and acidic fixatives, a good example
being Carnoy’s fluid which contains both alcohol
and glacial acetic acid

8. Decalcification
- strong acids tend to degrade DNA, making the decalcified
bone sections suboptimal for testing.
- Weak acids, although slower than the strong acid agents
in the decalcifying process, are much gentler in action and
less likely to interfere with nuclear staining

9. The monument to the
laboratory mouse
A little break!

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11. Nucleic acid
demonstrated by:
Feulgen technique.
Fluorescent method.
Gallocyanin chrom-
alum technique
Methyl green-pyronin
A
B
C
D

12. Feulgen reaction:
Mild acid hydrolysis, employing 1 M
hydrochloric acid at 60°C, is used to break
the purine-deoxyribose bond
the resulting ‘exposed’ aldehydes are then
demonstrated by the use of Schiff’s reagen
(plasmal reaction).
The method of Feulgen and Rossenbeck
(1924) is the
standard technique for demonstrating
deoxyribose.

13. Feulgen reaction:
Phospholipid may give feulgen reaction in
cryostat technique but not in paraffin technique.
Feulgen reaction used in conjunction with
micro-dinstomitry to study cancer (DNA
content in certain lymphoma is inverse to the
tumor prognosis).

14. Feulgen-naphthoic acid-hydrazide method
This technique can be used as control method for standard feulgen reaction
2-hydroxy-3-naphthoic acid
is coupled with fast blue B
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4
The reaction gives blue to
bluish purple colour.
0
5
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6
The sections are hydrolyzed in
1M HCl as in felgen reaction
0
1
This hydrolysis produces
aldehyde group
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2
The aldehyde couples with
2-hydroxy-3-naphthoic acid
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3

15. Gallocyanine-chrome
alum method:
It gives blue colour with both DNA and RNA.
The phosphoric acid of the nucleic acid of
both DNA and RNA combined with
gallocynin-chrome alum at acid PH.

16. Fluorescent method:
Acidine orange is an organic compound. It
interacts with DNA and RNA by interaction or
electrostatic attraction respectively.
DNA stained yellow-green and RNA stained red.
The most used method is acidine orange
technique.

17. Methyl green-pyronin:
Methyl green is specific for phosphate
radicals in the DNA double helix staining it
green-blue.
Pyronin does not posses this affinity and
binds to the remaining negatively charged
RNA staining it red.
Classical histological staining technique using
two basic (cationic) dyes for the demonstration
and defferentiation of DNA and RNA.
Methyl green is an impure dye containing
methyl violet which removed by washing by
chloroform, at PH 4,8.

18. Methods used for digestion of one of the nucleic
acid to make the applied technique specific for
the other one.
Digestion methods
for nucleic acid:

19. 0
1
0
2
Enzymatic
method:
Chemical extraction
method:
Specific enzymes can be
used to digest DNA and
RNA in tissue section
-Pure deoxyribonuclease :
removes DNA.
-- ribonuclease : removes
RNA
1- percloric acid.
2- tri-chlora acetic acid.
3- hydrochloric acid

20. Thank You
For your attention