Blotting Techniques: The Muscular System

Essentials of Anatomy & Physiology, 4th Edition
Martini / Bartholomew
BLOTTING TECHNIQUES
The Muscular
System
By
Abdullah Al-Hatami
PowerPoint Lecture Outlines
prepared by Alan Magid, Duke
University
PhD
student
College of Medicine
University of Kufa
What is blotting?
Blots are techniques for transferring DNA , RNA

and proteins onto a carrier so they can be
separated, and often follows the use of a gel
electrophoresis. The Southern blot is used for
transferring DNA, the Northern blot for RNA and
the western blot for PROTEIN.
TYPES OF BLOTTING
TECHNIQUES
Blotting technique
Southern Blot
Northern Blot
Western blot
It is used to detect DNA.It is used to detect RNA.

It is used to detect protein.
SOUTHERN BLOTTING
Professor Sir Edwin Southern,

Professor of Biochemistry and
Fellow of Trinity developed this
method in 1975.
Southern won the Lasker
Award for Clinical Medical
Research prize for the method
of finding specific DNA
sequences he developed this
procedure at Edinburgh
University more than 30 years
ago. The technique is known as
DNA transfer or 'Southern
blotting'
Professor Sir Edwin Souther
Cont.
This method Involves separation, transfer and

hybridization.
It is a method routinely used in molecular biology for

detection of a specific DNA sequence in DNA samples. The
DNA detected can be a single gene, or it can be part of a
larger piece of DNA such as a viral genome.
Cont.
Southern blotting combines agarose gel electrophoresis for

size separation of DNA with methods to transfer the size
separated DNA to a filter membrane for probe
hybridization.
The key to this method is Hybridization.
Hybridization - Process of forming a double-stranded DNA

molecule between a single-stranded DNA probe and a
single-stranded target patient DNA.
PRINCIPLE
1.
The mixture of molecules is separated.

2. The molecules are immobilized on a matrix.
3. The probe is added to the matrix to bind to the
molecules.
4. Any unbound probes are then removed.
5. The place where the probe is connected corresponds to
the location of the immobilized target molecule.
APPARATUS
Whatman 3MM paper
nitrocellulosemembrane
Capillary plotting apparatus
Steps in southern blotting

1. Digest the DNA with an
appropriate restriction
enzyme.
2.The complex mixture of

fragments is subjected to gel
electrophoresis to separate
the fragments according to
size.
Cont.
3.The restriction fragments
present in the gel are
denatured with alkali and
transferred onto
4. a nitrocellulose filter or nylon
membrane by blotting.
This procedure preserves the

distribution of the fragments
in the gel, creating a replica
of the gel on the filter.
Cont.
5.The filter is incubated under
hybridization conditions
with a specific radiolabeled
DNA probe.
The probe hybridizes to the

complementary DNA
restriction fragment.
Cont.
6.Excess probe is washed away and the
probe bound to the filter is detected
by autoradiography, which reveals the
DNA fragment to which the probe
hybridized.
APPLICATIONS
Southern blots are used in gene discovery , mapping,

evolution and development studies, diagnostics and
forensics (It is used for DNA fingerprinting, preparation of
RFLP maps)
identification of the transferred genes in transgenic

individuals, etc.
APPLICATIONS
Southern blots allow investigators to determine the

molecular weight of a restriction fragment and to measure
relative amounts in different samples.
Southern blot is used to detect the presence of a particular

bit of DNA in a sample
analyze the genetic patterns which appear in a person's

DNA.
Northern Blotting
Northern blotting is a technique for detection
of specific RNA sequences. Northern blotting
was developed by James Alwine and George Stark
at Stanford University (1979) and was named
such by analogy to Southern blotting
Steps involved in
Northern blotting
1. RNA is isolated from
several biological samples
(e.g. various tissues,
various developmental
stages of same tissue etc.)
* RNA is more susceptible
to degradation than DNA.
Cont
2. Samples are loaded on gel
and the RNA samples are
separated according to their
size on an agarose gel.
The resulting gel following

after the electrophoresis run.
Cont
3. The gel is then blotted on
a nylon membrane or a
nitrocellulose filter paper
by creating the sandwich
arrangement.
Cont
4. The membrane is placed in a
dish containing hybridization
buffer with a labeled probe.
Thus, it will hybridize to the RNA

on the blot that corresponds to
the sequence of interest.
5. The membrane is washed to

remove unbound probe.
Cont
6. The labeled probe is
detected via
autoradiography or via a
chemiluminescence reaction
(if a chemically labeled
probe is used). In both
cases this results in the
formation of a dark band on
an X-ray film.
Now the expression patterns

of the sequence of interest
APPLICATIONS
A standard for the study of gene expression at the

level of mRNA (messenger RNA transcripts)
Detection of mRNA transcript size
Study RNA degradation
Study RNA splicing
Study RNA half-life
Often used to confirm and check transgenic /

knockout mice (animals)
Disadvantage of
Nourthern plotting
1.The standard northern blot method is relatively less
sensitive than nuclease protection assays and RT-PCR
2. Detection with multiple probes is a problem
3. If RNA samples are even slightly degraded by RNases, the
quality of the data and quantitation of expression is quite
negatively affected.
Western blotting
Western blotting (1981) is an Immunoblotting technique

which rely on the specificity of binding between a protein of
interest and a probe (antibody raised against that particular
protein) to allow detection of the protein of interest in a
mixture of many other similar molecules.
The SDS PAGE technique is a prerequisite for Western

blotting .
Steps in western blotting

1.
A protein sample is
subjected to electrophoresis
on an SDS-polyacrylamide
gel.
2.
Electroblotting transfers the

separated proteins from the
gel to the surface of a
nitrocellulose membrane.
Cont
3. The blot is incubated with a generic protein
(such as milk proteins or BSA) which binds to
any remaining sticky places on the
nitrocellulose.
4. An antibody that is specific for the protein of

interest (the primary antibody - Ab1) is added
to the nitrocellulose sheet and reacts with the
antigen. Only the band containing the
protein of interest binds the antibody,
forming a layer of antibody molecules .
Cont
5. After washing for removal of nonspecifically bound Ab1, second
antibody (Ab2)is added, which
specifically recognizes the Fc domain
of the primary antibody and binds it.
Ab2 is radioactively labeled, or is
covalently linked to a reporter
enzyme, which allows to visualize the
protein-Ab1-Ab2 complex.
An example
Application
1.The confirmatory HIV test
2.Western blot is also used as the definitive test
for Bovine spongiform encephalopathy (BSE(
3.Some forms of Lyme disease testing employ Western
blotting.

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Essentials of Anatomy & Physiology, 4th Edition

Blots are techniques for transferring DNA , RNA

It is used to detect DNA.It is used to detect RNA.

Professor Sir Edwin Southern,

Professor Sir Edwin Souther

This method Involves separation, transfer and

It is a method routinely used in molecular biology for

Southern blotting combines agarose gel electrophoresis for

The key to this method is Hybridization.

Hybridization - Process of forming a double-stranded DNA

The mixture of molecules is separated.

Whatman 3MM paper

Capillary plotting apparatus

Steps in southern blotting

2.The complex mixture of

This procedure preserves the

The probe hybridizes to the

Southern blots are used in gene discovery , mapping,

identification of the transferred genes in transgenic

Southern blots allow investigators to determine the

Southern blot is used to detect the presence of a particular

analyze the genetic patterns which appear in a person's

The resulting gel following

Thus, it will hybridize to the RNA

5. The membrane is washed to

Now the expression patterns

A standard for the study of gene expression at the

Detection of mRNA transcript size

Study RNA degradation

Study RNA splicing

Study RNA half-life

Often used to confirm and check transgenic /

Western blotting (1981) is an Immunoblotting technique

The SDS PAGE technique is a prerequisite for Western

Steps in western blotting

Electroblotting transfers the

4. An antibody that is specific for the protein of

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