95. In animal cloning protocol, while performing enucleation, which chemical is used for relaxing
the cellular cytoskeleton?
A. Phytohaemagglutinin
B. Cytochalasin B
C. Pronase
D. Heparin

Detailed Explanation:

In animal cloning protocols, one of the critical steps is enucleation, where the nucleus is removed from an egg cell in preparation for transferring a donor nucleus. This step is essential for creating a viable zygote in cloning, as it allows the reprogramming of the donor DNA to direct the development of a new organism.

To ensure that enucleation is successful, the cytoskeleton of the egg cell must be manipulated. The cytoskeleton is responsible for maintaining the cell’s shape and structure, and its stability must be temporarily altered to facilitate the removal of the nucleus.

Chemical Involved in Relaxing the Cytoskeleton:

The chemical commonly used to relax the cellular cytoskeleton during enucleation in animal cloning is Cytochalasin B. Cytochalasin B is a cytoskeletal disruptor that interferes with the function of actin filaments. By disrupting the actin network, Cytochalasin B helps relax the cytoskeleton, making it easier to manipulate the cell and remove the nucleus.

Why is Cytochalasin B Used?

• Cytoskeletal Disruption: Cytochalasin B specifically inhibits actin polymerization, leading to the disruption of the cytoskeletal structure. This makes the cell membrane more malleable and allows researchers to carefully extract the nucleus without damaging other cellular components.

• Enucleation Process: The relaxed cytoskeleton allows the egg cell to be more amenable to nuclear transfer, which is crucial for the success of cloning.

Other Chemicals in Cloning Protocols:

• Phytohaemagglutinin: This is a plant-derived protein used to induce cell division in some protocols, but it does not play a role in relaxing the cytoskeleton.

• Pronase: This enzyme is used to digest proteins on the surface of the cell, but it is not involved in relaxing the cytoskeleton.

• Heparin: Heparin is an anticoagulant and is used to prevent clotting in biological experiments but does not have an impact on the cytoskeleton in the context of cloning.

Conclusion:

In animal cloning protocols, Cytochalasin B is used to relax the cellular cytoskeleton during enucleation. This chemical is crucial for ensuring that the egg cell can undergo nuclear transfer effectively, making it a fundamental component in the success of cloning procedures.

Correct Answer:

B. Cytochalasin B