Chromosome Walking and Characterizations of Chromosome Segments, Gene Sequence, genomic Library, Number of Clones, Different Genomes

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Chimeric DNA Molecular Probes and Gene Libraries Chimeric DNA Molecular Probes and Gene Libraries Introduction Restriction Enzymes for Cloning Technique of Restriction Mapping Restriction Clevage and Gel Electrophoresis Construction of a Restriction Map Use of Partial Digests end Labelling and Hybridization in Restriction Mapping Construction of Chimeric DNA Cloning of Plasmid Vectors Directional Cloning of DNA Fragments with Heterologus Protruding Termini Adding Poly dA at 3' Ends of DNA Clone Blunt End Ligation by T4 DNA Ligase Cloning in Phage λ and Cosmid Vectors Cloning in phage λ Vectors Cloning in Cosmid Vectors Hosts for Cloning Vectors Bacteria as Hosts Eukaryotes as Hosts Molecular Probes Preparation of Probes Genomic DNA Probes

Home >> Biotechnology and Genomics >> Chimeric DNA Molecular Probes and Gene Libraries >> Chromosome Walking and Characterizations of Chromosome Segments

Your Ad Here	Chromosome Walking and Characterizations of Chromosome Segments When a probe is used for the identification of a gene sequence in a genomic library, the probe may hybridize with a number of clones, each carrying a part of a large gene fragmented during preparation of genomic library. If we obtain partial digests (by digesting the DNA only partially) from the genome, different genomes (form large number of cells) may give fragments which have overlapping sequences, because sites cleaved in different genomes of the same organism will differ being random. Since none of these fragments may have entire sequence represented in the probe, overlapping sequences may be used to construct the original genomic sequence.
Identification of fragments with overlapping sequences may be a key to the reconstruction or characterization of large chromosome regions. This is achieved by the technique popularly described as chromosome walking. The technique of chromosome walking involves the following steps: (i) from the genomic library, a clone of interest (identified by a probe) is selected and a small fragment is subcloned from one end of the clone (there is a technique available to subclone a fragment from the end); (ii) the subcloned fragment of the selected clone may be hybridized with other clones in the library and a second clone hybridizing with the subclone of the first clone is identified due to presence of overlapping region;
(iii) the end of the second clone is then subcloned and used for hybridization with other clones to identify a third clone having overlapping region with the subcloned- end of the second clone; (iv) the third clone identified as above is also subcloned and hybridized with clones in the same manner and the procedure may be continued; (v) restriction maps of selected overlapping clones may be prepared and compared to know the region of overlapping as,so that identification of few overlapping restriction sites will amount to walking along the chromosome or along a long chromosome segment.	Your Ad Here
The technique of chromosome walking through successive hybridization between Overlapping genomic clones Regions of chromosomes approaching 1000kb have been mapped following the above technique. Restriction maps of entire chromosomes can be prepared in this manner following the technique of chromosome walking.

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c DNA Probes Synthetic Oligonucleotides as Probes RNA Probes or Riboprobes Labelling of Probes Radiolablled Probes Non Radioactive Probes Biotin Labelled Probes Digoxigenin Labelled Probes Alternatives to Biotin and Digoxigenin Labelling Amplification of DNA Probe Signals Techniques Used in Molecular Probing Southern Nothern and Western Blotting Southern Blotting Northern Blotting Western Blotting Dot Blots and Slot Blots Applications of Molecular Probes Construction and Screening of Genomic and cDNA Libraries Genomic Library by Shotgun Experiment cDNA Library from mRNAs Colony or Plaque Hybridization for Screening of Libraries Chromosome Walking and Characterization of Chromosome Segments Chromosome Jumping or Hopping Libraries BAC Libraries and Assembly of BACs into Contigs

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