Introduction to Biotechnology
What are reasons to make transgenic animals?
To make a model animal to study animal diseases
Introduce economical important traits in farm animals
For production of antibody and growth hormones
Help transfer genes across species
What methods are used in gene transfer?
Embryonic stem cell-mediated gene transfer
Retrovirus-mediated gene transfer
What are the steps in DNA microinjection?
Identify the gene of interest
Clone the gene in the proper vector
Microinject the cloned gene directly into the pronucleus of a single fertilized egg before first cell division occurs
Implant the egg into surrogate mother
Allow embryo to develop to birth
Demonstrate that the foreign gene has been incorporated into the host genome and it is heritable in at least one offspring.
What are the potential problems in microinjection?
Few injected eggs survive
The gene inserts itself into chromosome at random
Not all of the cells in the animal receive the gene
The gene is not expressed in large enough amounts
What is embryonic stem cell gene transfer?
Producing differentiated cells from undifferentiated cells, by maintaining the potential of undifferentiated stem cells
Used for targeted gene replacement (put the gene on the right chromosome)
What are the steps in embryonic stem cell gene transfer?
ES cells removed from embryo
Transfection- Gene of interest is inserted in the the embryo
The gene is targeted by homologous recombination and selective markers
The ES cells with the correct gene are inserted into blastocysts (partially developed embryos) which are implanted into the mother animal
Offspring are screened for trait of interest
What are the uses of embryonic stem cells?
Study human diseases
Study growth and developement
To inactivate or insert gene
What are the two ways of gene targeting?
Knock-in - Insert genes into specific site on chromosome
Knock-out - Remove a gene or part of a gene to inactivate it
How is a retrovirus used to integrate genes into a recipient organism?
By infecting the organism with virus carrying the gene
The desired gene can be integrated into the host chromosome
What make an animal transgenic?
Animals have genes from other species
Genes either knock-in or knock-out
What are the uses of transgenic animals?
They are modified to resist diseases and environmental stress
They are used to manufacture proteins, clotting factors, hormones, growth factors
What is Xenotransplantation?
The use of animal organs in human patients
What is the animal of choice for Xenotransplantation and why?
They are easy to raise and breed
Have similar sized organs
Can be genetically engineered and cloned
What are the concerns about xenotransplants?
Loss of litter mates
Fear of diseases
Required method to screen PERV free organ and organ is not rejected
What are some animal health concerns
Foot and mouth disease
Mad cow disease
What is artificial insemination?
Allows genetically desirable animals to be bred more efficiently and frequently
Increase genetic diversity of endangered animals
What is conservation biology?
It is used to preserve and protect endangered species of animals
What techniques are used in conservation biology?
Invitro fertilization for controlled breeding
Cryopreservation of gametes
Embryo transfer-preserving fertilized eggs
What are the causes for concern for animal clones?
Animals have many problems- Early death, low cloning success, oversized animals, physical deformities, medical problems
Introduction to Biotechnology