Which technique uses a fine glass pipette to deliver DNA into the nucleus of a fertilized egg?

Which technique uses a fine glass pipette to deliver DNA into the nucleus of a fertilized egg?

• A. Intraembryonic injection
• B. Retroviral insertion
• C. Embryonic stem cell insertion
• D. Pronuclear injection

Answer: (D)

Delivering DNA directly into the nucleus of a fertilized egg with a fine glass micropipette is a microinjection approach known as pronuclear injection. By injecting the DNA into the pronucleus at the one-cell stage, the transgene can be incorporated into the genome as the embryo divides, allowing the new gene to be passed to the germline and present in all cells of the resulting animal. This method is a direct way to create transgenic organisms right at the earliest developmental stage. It differs from injecting into the embryo at later stages (which may affect specific tissues rather than ensuring germline transmission), from using a viral vector to deliver DNA (which relies on viruses rather than precise nucleus injection), and from modifying embryonic stem cells in culture and then generating an animal from those cells (which starts with cultured cells rather than the zygote itself).

Delivering DNA directly into the nucleus of a fertilized egg with a fine glass micropipette is a microinjection approach known as pronuclear injection. By injecting the DNA into the pronucleus at the one-cell stage, the transgene can be incorporated into the genome as the embryo divides, allowing the new gene to be passed to the germline and present in all cells of the resulting animal. This method is a direct way to create transgenic organisms right at the earliest developmental stage. It differs from injecting into the embryo at later stages (which may affect specific tissues rather than ensuring germline transmission), from using a viral vector to deliver DNA (which relies on viruses rather than precise nucleus injection), and from modifying embryonic stem cells in culture and then generating an animal from those cells (which starts with cultured cells rather than the zygote itself).