UNIT 7.2: Chromosome Banding Flashcards
A part of a chromosome which is clearly distinguishable from its adjacent segments by appearing darker or lighter
band
History of Chromosome Banding
In 1958, Caspersson et al., published their first paper describing the use of ____ to stain chromosome there by ushered in a new era of chromosome banding
Quinacrine mustard
a fluorescent dye
History of Chromosome Banding
The ____ was the first attempt to provide nomenclature for chromosome banding in any species and thus its recommendations have been adopted to nonhyman species as well
The Paris report (1971)
Why study banding pattern?
allows you to see smaller pieces of the chromosome, so that you could identify smaller structural chromosome abnormalities not visible on a routine analysis
Classification of Banding Techniques
Q
Quinacrine
Casperson et al. (1958)
Classification of Banding Techniques
G
Giemsa
Summer et al. (1971)
Classification of Banding Techniques
N
NOR
Matsui & Sasaki (1973)
Classification of Banding Techniques
C
Centromeric
Linde & Laursen (1978)
Q-banding
Staining technique used in Q-banding
Quinacrine (QTQ)
Q-banding
Microscope Used in Q-banding
Fluorescent microscope
Q-banding
Uses and advantages of Q-banding
- ID of all chromosomes and bands
- Reveals polymorphisms on chromosomes 3,4,13,15,21,22 and Y
- easily destained for sequential staining
G-banding
Staining techniques used in G-banding
- Giemsa (GTG)
- Wrights
G-banding
Microscope used in G-banding
Brightfield microscope
G-banding
Uses and advantages of G-banding
- ID of all chromosomes and bands
- Permanent stain
- Simple photography
R-banding (Reverse banding)
Staining techniques used in R-banding
- Giemsa (RHG)
- CH3/DA
R-banding (Reverse banding)
Microscopes used in R-banding
- Brightfield microscope- Giemsa (RHG)
- Fluorescent microscope - CH3/DA
R-banding (Reverse banding)
Uses and advantages of R-banding
- ID of all chromosomes and bands
- Visualization of ends of chromosomes and small positive R-bands
Replication banding
Staining techniques used in Replication banding
- Hoechst
- Hoechst and Giemsa
Replication banding
Staining techniques used in Replication banding
- Hoechst
- Hoechst and Giemsa
Replication banding
Microscopes used in Replication banding
- Fluorescent microscope -Hoechst
- Brightfield microscope- Hoechst and Giemsa
Replication banding
Uses and advantages of Replication banding
ID of all chromosomes and bands, and of inactive, late-replicating X chromosome
C-banding
Staining techniques used in C-banding
Giemsa (CBG)
C-banding
Microscope used in C-banding
Brightfield microscope
C-banding
Uses and advantages of C-banding
- ID of all centromeric and distal Y heterochromatin
- Reveals polymorphisms including heterochromatin inversions
- Evaluation of ring and dicentring chromosomes
NOR banding
Staining technique used in NOR banding
AgNO3
NOR banding
Microscope used in NOR banding
Brightfield microscope
NOR banding
Uses and advantages of NOR banding
- ID of active NOR
- reveals polymorphisms and rearrangements of acrocentric chromosomes
DA-DAPI staining
Staining techniques used in DA-DAPI staining
- Distamycin A/DAPI
- distamycin A/Hoechst
DA-DAPI staining
Microcope used in DA-DAPI staining
Fluorescent microscope
DA-DAPI staining
Uses and advantages of DA-DAPI staining
- ID of centromeric heterochromatin regions of chromosomes 1,9,15,16,and Y
- Useful in evaluation of chromsome 15-derived markers
Type of Banding
- Giemsa stain
- AT-rich regions stain darker than GC-rich regions
G-banding
Type of Banding
Quinacrine fluorescent dye stains AT-rich regions
Q-banding
Type of Banding
- Banding pattern is opposite G-banding
- GC-rich regions stain darker than AT-rich regions
R-banding
Type of banding
- Stains heterochromatic regions close to the centromeres
- Usually stains the entire long arm of the Y chromosome
- Denaturation with barium hydroxide followed by giemsa
- The dark bands represent heterochromatin near centromere
C-banding
Q Banding Techniques
The __ __ region quenches dye and fluorescence, situated in heterochromatin region
AT region
For Region rich in AT bases (dark staining)
Q Banding Techniques
The __ __ region quenches dye but do not fluorescence, situated in euchromatin region
GC region
For Region rich in GC bases (light staining)
Q Banding Techniques
Advantages of Q banding
- Simple and versatile
- Used where G band is not accepted
- Used in study of chromosome heteromorphism
Q Banding Techniques
Disadvantages of Q banding
- Tendency to fade during examination (photo-degredation)
- Chromophore - absorb light of a particular wavelength due to chemical bond formed between dye and light, UV light breaks the chemical bond
G banding Techniques
Used to denature protein
Weak trypsin/ Urea / Protease
G banding Techniques
Interaction of the DNA with thiazine and eosine components of sysin brightens sulfur rich regions
When treated with Giemsa
G banding techniques
Different types of Giemsa stains
- Methylene Azure
- Methylene Violet
- Methylene Blue
G banding Techniques
Advantages of G banding
- Identification of bands rich in sulfur content
- Identification of chromosomal abnormalities
- Gene mapping
G banding Techniques
Disadvantages of G banding
Not used in plants
N Banding
After air drying the chromosome, it will be treated with 5% ____ at 95 °C for _____ mins
Trichloroacetic acid
30 minutes
N banding
After being treated with Trichloroacetic acid, it will be treated with 0.1N ____ at 60°C for 30 minutes
HCl
N banding Techniques
What are the advantages of N banding?
- Identification of nucleolar organizer region
- Superior banding pattern for plants
N banding techniques
What is the disadvantage of N banding technique?
The chemicals (TCA & HCl) create fumes which may be harmful
C banding technique
After harvesting the chromosome, what will it be treated with?
Alkali solution
DNA denaturing takes place
C banding technique
After being treated with Alkali solution, it will be washed with ___ at 60°C for 30 minutes
Sodium Citrate
Repeatative DNA renature but unique DNA do not renature
C banding technique
C banding only stains what?
since sodium citrate renatures them
heterochromatins
C banding techniques
Advantages of C banding techniques
- Identification of chromosomes, particularly in insects and plants
- Identification of bivalents at diakinesis using both centromere positions
- Paternity testing
- Gene mapping
Representation of a chromosome band
What is another term for the short arm of a chromosome?
p (for petit)
Representation of a chromosome band
What is another term for the long arm of a chromosome?
q (for queue)
Representation of a chromosome band
Short arm and long arm is seperated by a what?
a centromere
Representation of a chromosome band
Each chromosome arm is divided into regions that is called?
Cytogenetic bands
that can be seen using a microscope and special stains
Representation of a chromosome band
The cytogenetic bands are labeled ____ counting from the centromere out toward the telomeres
p1,p2,q1,q2, etc
Representation of a chromosome band
At higher resolutions, ____ can be seen within the bands. These are also numbered from the centromere out toward the telomere
sub-bands
Representation of a chromosome band
Example of a cytogenetic map location of a gene:
7q31.2
This indicates that the gene is on chromosome 7, q arm, band 3, sub-band 1, sub-sub band 2
Representation of a chromosome band
End of chromosomes are labeled ____ and ____
ptel and qtel
Representation of a chromosome band
The notation 7qtel refers to?
the telomeric end of the q-arm of chromosome 7
ISCN
International System for Human Cytogenetic Nomenclature