Describe the principle and method of whole animal cloning. 9IAS 2023/15 Marks Marks)

Introduction

Whole animal cloning is a process that involves creating an exact genetic copy of an organism. This technique has been successfully used in various species, including mammals, to produce genetically identical individuals. The principle behind whole animal cloning lies in the ability of a single cell to develop into a complete organism. 

Principle of Whole Animal Cloning

• Genetic Copy Creation
  
  • Whole animal cloning aims to produce an organism genetically identical to the donor animal.
  • This process involves creating a clone with the same DNA sequence, ensuring all genetic characteristics are preserved.
• Somatic Cell Nuclear Transfer (SCNT)
  
  • The primary technique for whole animal cloning is SCNT, where the nucleus of a somatic (body) cell is transferred to an enucleated egg cell.
  • This method bypasses the need for sexual reproduction and creates an embryo genetically identical to the donor.
• Reprogramming of DNA
  
  • The DNA of the donor somatic cell is reprogrammed in the egg environment, which restores its developmental potential.
  • This reprogramming enables the somatic cell to initiate embryo development and differentiate into various tissues and organs.
• Embryonic Development Process
  
  • The newly formed zygote undergoes normal embryonic development stages, eventually developing into a clone of the donor animal.
  • The clone undergoes identical processes of cellular differentiation and organ formation as a naturally fertilized embryo.
• Role of Epigenetic Factors
  
  • Although the DNA sequence remains the same, epigenetic factors (modifications on DNA that affect gene expression) play a role in the development and differentiation of cloned embryos.
  • These factors can affect the expression of certain genes, which may impact the clone's physical and physiological characteristics.

Method of Whole Animal Cloning

• Somatic Cell Collection
  
  • A somatic cell, usually from the skin or another easily accessible tissue, is collected from the donor animal.
  • This cell contains the complete set of chromosomes with the genetic information needed for cloning.
• Enucleation of Egg Cell
  
  • An egg cell is harvested from a female animal and its nucleus is removed, leaving behind an enucleated cell.
  • This enucleated egg will serve as the recipient for the donor DNA.
• Nuclear Transfer
  
  • The nucleus from the donor somatic cell is inserted into the enucleated egg cell.
  • The egg, now containing the donor's DNA, is stimulated (often with electric pulses) to begin dividing as a fertilized egg would.
• Embryo Culture and Development
  
  • The egg begins dividing and develops into an embryo in a lab setting.
  • Once it reaches a certain developmental stage, it is ready to be implanted.
• Implantation into Surrogate Mother
  
  • The developing embryo is implanted into the uterus of a surrogate mother for gestation.
  • The surrogate carries the embryo to term, and the cloned animal is born, genetically identical to the donor.

Conclusion

Whole animal cloning has revolutionized the field of genetics and has opened up new possibilities for research and conservation efforts. Despite the ethical concerns surrounding cloning, this technique has the potential to make significant contributions to the field of zoology and beyond.