6. Which of the following is NOT used for the generation of transgenic animals?
a. Somatic cell nuclear transfer
b. Pronuclear injection
c. Embryonic stem cells
d. Next-generation sequencing
Answer: d. Next-generation sequencing
Next-generation sequencing (NGS) analyzes DNA sequences but does not introduce foreign genes into animal genomes for transgenic production.
Option Analysis
Somatic Cell Nuclear Transfer (SCNT)
SCNT modifies somatic cells with transgenes in culture, then transfers their nuclei into enucleated oocytes to generate transgenic animals like cloned cattle and pigs.
This method confirms modifications before embryo production, especially useful where embryonic stem cells are unavailable.
Pronuclear Injection
Pronuclear injection microinjects DNA directly into zygote pronuclei, a standard method for creating transgenic mice, rabbits, and livestock since the 1980s.
Fertilized eggs integrate the transgene randomly upon implantation, enabling stable germline transmission.
Embryonic Stem Cells
Embryonic stem (ES) cells incorporate transgenes via homologous recombination, followed by injection into blastocysts to produce chimeras and transgenic offspring.
This allows screening for targeted integrations before animal generation, common in mice.
Next-Generation Sequencing
NGS sequences genomes to detect or map transgenes post-production but plays no role in gene insertion or animal creation.
Transgenic animals carry foreign genes for research, agriculture, and medicine. Common techniques for generation of transgenic animals include physical and cell-based approaches.
Core Methods
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Pronuclear Injection: DNA enters zygote pronuclei for random integration, widely used in mammals.
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Somatic Cell Nuclear Transfer: Genetically altered somatic nuclei reprogram in oocytes, ideal for livestock transgenics.
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Embryonic Stem Cells: Modified ES cells create chimeras yielding germline transgenics, precise for mice.
Excluded Technique
Next-generation sequencing verifies transgenes but does not generate them.
This aligns with CSIR NET Life Sciences questions testing method distinctions.
