19. A proto-oncogene is suspected to have undergone duplication in a certain type of cancer. Of the
following techniques, which one would verify the gene duplication?
(a) Northern blotting (b) Southern blotting
(c) South western blotting (d) Western blotting
Southern blotting stands out as the precise technique to confirm proto-oncogene duplication in cancer samples. This method directly analyzes DNA structure changes like gene copy number increases, which transform proto-oncogenes into oncogenes driving tumor growth. Unlike other blotting methods, it uses restriction enzyme digestion to reveal extra gene copies through additional or shifted bands on gels.
Correct Answer
The right choice is (b) Southern blotting. In cancer research, proto-oncogene duplication amplifies gene dosage, detectable by digesting genomic DNA with restriction enzymes, separating fragments via electrophoresis, and probing for the target sequence. Multiple bands or increased intensity indicate duplication, distinguishing it from single-copy normal DNA, as validated in gene copy number studies.
Why Other Options Fail
Northern blotting (a) targets RNA transcripts, measuring expression levels but missing DNA-level duplications. South western blotting (c) combines Southern and Western methods to detect DNA-protein interactions, irrelevant for pure gene copy verification. Western blotting (d) assesses protein levels post-translation, unable to confirm genomic DNA changes like duplications.
Blotting Techniques Comparison
| Technique | Target Molecule | Key Use | Detects Gene Duplication? |
|---|---|---|---|
| Northern (a) | RNA | Gene expression analysis | No |
| Southern (b) | DNA | Copy number, mutations, RFLP | Yes |
| South Western (c) | DNA-Protein | Transcription factor binding | No |
| Western (d) | Protein | Protein abundance, modifications | No |
This table highlights Southern blotting’s unique role in DNA structural analysis for cancer genomics.
Applications in Cancer Research
Southern blotting remains valuable for verifying oncogene amplifications despite newer methods like qPCR or NGS, especially in confirming large duplications or restriction fragment length polymorphisms (RFLP). Biotech professionals use it in diagnostics for repeat expansions linked to diseases, aiding precise oncogene studies in molecular biology workflows.
