Question

Methods of cloning organisms: embryo splitting, cell fusion, nuclear transfer

Answer 1

Cloning:

Cloning is the technique which involves the production of identical copies of the cell or organism.

Embryo splitting:

Embryo splitting is the technique in which the early 2 cell stage of the embryo is split to two individual cells and grown as two identical embryos.

This technique was also done in 4-cell stage good success rate was obtained.

But when this technique was done in 6 to 8 cell stage its efficiency reduced.

Somatic cell nuclear transfer:

In this technique the nucleus of the somatic cell is transferred to the egg cell, the nucleus of the egg is removed. The egg is then allowed to develop,

In the year 1996 Dolly the sheep was successfully cloned by fusing a nucleus from the mammary gland cell of a Finn Dorset ewe into an enucleated egg cell. The embryo was then developed in a surrogate mother and dolly was produced.

Technique of nuclear transfer:

• It involves viewing the egg cell under the microscope.
• A holding pipette with small vacuum is used to hold the egg cell in place.
• A micropipette is used to remove the nucleus of the cell.
• In some species a drill is used to pierce the egg cell layers.
• After the nucleus of the egg is removed the cell fusion is done to fuse the somatic cell with the egg cell.
• The fusion involves the transfer of nucleus to the egg cell.
• After the nuclear transfer the egg cell develops to embryo.
• The embryo is then transferred to the foster mother.

Thus dolly was produced by this method.

Cell fusion:

Cell fusion is the technique by which two cells fuse to form single cell.

Cell fusion can be done by 3 methods

Electrical cell fusion:

Electrical pulse is applied to the two cells. The electrical pulse permeate the cell membranes and fuses the two cells.

PEG:

Poly ethylene glycol is the dehydrating agent which fuses the plasma membrane.

This type of cell fusion is used to generate somatic cell hybrids and for nuclear transfer in cloning.

Sendai virus:

Sendai virus induces the fusion of two cells.