technique about Chromosome walking and its applications and drawbacks

1. Chromosome walking

2. Introduction
• Chromosome walking is a method of
positional cloning used to find, isolate, and
clone a particular allele in a gene library.
• Developed by Welcome Bender, Pierre Spierer,
and David S. Hogness in the Early 1980's.

3. KNOWN
Construction of library

4. 1A DNA fragment from a
chromosome contains and
identify sequence (usually
a gene)
Fragment 2
2
Fragment 1
Fragment 3
Prepare restriction map
Use this sequence as probe
Probe produced by subcloning ; subclone -1
Hybridize with clones from genomic library
Isolate fragment-2 prepare
restriction map of fragment-2
Successive fragments
1
2
3
1 2 3
Overlapping
sequences
Use this sequence as probe
Probe produced by subcloning ; subclone -2
Hybridize with clones from genomic library
3

7. Application
• The analysis of genetically transmitted diseases, to look for
mutation
• Discovery of single-nucleotide polymorphism of different
organisms.
• To know the unknown flanking region of the chromosome
• Now a days it can be use for the metagenomics process to
know the genome sequence of the unknown organism

8. Disadvantages
• Speed of chromosome walking
• Difficulty of walking through the repeated sequence that are
scattered through the gene.
• Chromosome walking could easily be stopped by un clonable
sections of DNA.
• A solution to this problem was achieved with the advent of
chromosome jumping (Marx, 1989), which allows the skipping
of unclonable sections of DNA