What are transgenic animals definition production process types and applications
Animals that have modified genomes are called Transgenic Animals. A foreign gene is being inserted into the genome of the animal with the purpose to alter its DNA. To improve the genetic traits of the target animals, this method is used. Earlier, selective breeding methods were used for the improvement of these genetic traits. In this method, the animals were mated to produce an individual with improved genetic characteristics with the desired genetic traits. This time-consuming and expensive method was later replaced by recombinant DNA technology. These genes are passed on to successive generations. Transgenic animals are genetically modified and are therefore known as Genetically Modified Organisms. The first genetically modified organism was engineered in the year 1974 by Rudolph Jaenisch. He injected the SV40 virus in early mouse embryos and developed a transgenic mouse.
Methods for Creating Transgenic Animals
Following methods are used for creating the Transgenic Animals -
Physical Transfection
In this method, the gene of interest is directly injected into the pronucleus of a fertilized ovum. It is the very first method that proved to be effective in mammals. This method is applied to a wide variety of species. Other methods of physical transfection include particle bombardment, ultrasound, and electroporation.
Chemical Transfection
One of the chemical methods of gene transfection includes transformation. In this method, the target DNA is taken up in the presence of calcium phosphate. The DNA and calcium phosphate co-precipitates, which facilitates DNA uptake. The mammalian cells possess the ability to take up foreign DNA from the culture medium.
Retrovirus-Mediated Gene Transfer
To increase the chances of expression, the gene is transferred utilizing a vector. Since retroviruses can infect the host cell, they are used as vectors to transfect the gene of interest into the target genome.
Viral Vectors
Viruses are used to transfect rDNA into the animal cell. The virus can infect the host cell, express well, and replicate efficiently.
Bactofection
The gene of interest is transferred into the target gene with the help of bacteria with this process.
Examples of Transgenic Animals
Following are some of the examples of transgenic animals:
Transgenic Fish
Genetic transfer has been done in various fishes such as common carp, Atlantic salmon,etc. Transgenic salmon was the first genetically modified animal for food production.
Transgenic Chicken
D.W.Salter and L.B.Crittenden produced an avian leukosis virus resistant strain of the chicken in the year 1987.
Transgenic Rabbit
The first transgenic rabbit was successfully produced in 1985. They are used in the field of molecular farming.
Transgenic Cow
The name of the first transgenic cow is Rosie and it was developed in 1997. They are mainly developed with two objectives- increased milk production and molecular farming.
Transgenic Sheep
The first mammal to be produced from an adult cell was a sheep. The sheep’s name was Dolly. In this, the udder cells from a 6-year-old Finn Dorset white sheep were injected into an unfertilized egg from a Scottish Blackface ewe, which had its nucleus removed. Electrical pulses were used to fuse the cells. After the fusion of the nucleus of the cell with the egg, the resultant embryo was cultured for six to seven days. A transgenic sheep, Dolly was born by implantation into another Scottish Blackface ewe. Generally, transgenic sheeps are produced in order to achieve better meat production.
Transgenic Mice
Transgenic mice take birth when DNA is injected into the oocytes or one or two-celled embryos obtained from female mice after hormonal treatment. After injecting the DNA, the embryo is implanted into the uterus of receptive females.
Benefits Of Transgenic Animals
Some of the benefits of transgenic animals are -
Normal Physiology and Development
The growth factor is altered by introducing a foreign gene in transgenic animals. These animals facilitate the study of gene regulation and its effect on the everyday functions of the body.
Study of Diseases
These transgenic animals are specially designed to study the functions of genes in the development of certain diseases. Moreover, to take out a solution to disease, transgenic animals are used as model organisms. These transgenic models are used in research for the development of medicines. For example, we have transgenic models for diseases such as Alzheimer’s and cancer.
Biological Products
Transgenic animals are useful in obtaining biological products such as medicines and nutritional supplements. Some of the biological products such as medicines and nutritional supplements are produced and obtained from transgenic animals. Research for the manufacture of medicines to treat diseases such as phenylketonuria (PKU) and hereditary emphysema is going on. Rosie was the first transgenic cow in 1997 who produced milk that was rich in human protein. She produced about 2.4 grams per liter of milk. This milk contains the human gene alpha-lactalbumin and could be given to babies as an alternative to natural cow milk.
Vaccine Safety
For testing the safety of the vaccines, these transgenic animals are used as models before they are injected into humans. Mostly, this was done on Monkeys.
Conclusion:
Transgenic animals are close cousins to cloned animals with a slight technicality. It is interesting to read about technological advancement and evolution of species. Imagine if humans could be transgened for better outcomes. This article gives you a thorough understanding of modified genomes and their role in transgenic animals, methods of their creation, and popular examples. You can read it through to prepare better on the topic.
FAQs on Transgenic Animals in Biotechnology and Genetic Engineering
1. What are transgenic animals?
Transgenic animals are genetically modified organisms that carry a foreign gene deliberately inserted into their genome using genetic engineering techniques. The inserted gene, called a transgene, is usually taken from another species to express a desired trait.
- The transgene integrates into the host DNA.
- It becomes a stable part of the organism’s genome.
- The new trait can be inherited by offspring.
2. How are transgenic animals produced?
Transgenic animals are produced by inserting a foreign gene into a fertilized egg or embryo using molecular biotechnology methods. The basic steps include:
- Isolation of the desired gene using recombinant DNA technology.
- Insertion of the gene into a vector.
- Introduction of the gene into an embryo by microinjection, viral vectors, or CRISPR-Cas9.
- Implantation of the modified embryo into a surrogate mother.
3. What is the purpose of creating transgenic animals?
The main purpose of creating transgenic animals is to study gene function and produce useful biological products. They are used for:
- Medical research to study human diseases.
- Production of therapeutic proteins like insulin and antithrombin.
- Improving livestock traits such as growth rate and milk quality.
- Testing drug safety and efficacy.
4. What is a transgene?
A transgene is a foreign gene that is artificially introduced into the genome of an organism. It is designed to:
- Express a specific protein.
- Modify a biological trait.
- Study gene regulation and expression.
5. What are some examples of transgenic animals?
Examples of transgenic animals include genetically modified mice, sheep, fish, and goats engineered for research or production purposes. Notable examples are:
- Oncomouse, developed for cancer research.
- Transgenic sheep producing human proteins in milk.
- GloFish, fluorescent fish containing jellyfish genes.
- Goats producing the drug antithrombin in milk.
6. What is the difference between transgenic and genetically modified animals?
All transgenic animals are genetically modified, but not all genetically modified animals are transgenic.
- Genetically modified animals have any deliberate change in their DNA.
- Transgenic animals specifically contain a gene from another species.
7. How do transgenic animals help in medical research?
Transgenic animals help in medical research by acting as models to study human diseases and test new treatments. They are used to:
- Understand genetic disorders like cystic fibrosis and cancer.
- Study gene expression and mutation effects.
- Evaluate drug safety before human trials.
8. Can transgenic animals pass their traits to offspring?
Yes, transgenic animals can pass their traits to offspring if the transgene is integrated into the germ line cells. When the foreign gene is present in sperm or egg cells:
- The trait becomes heritable.
- It follows normal patterns of genetic inheritance.
- Future generations may consistently express the trait.
9. What are the advantages and disadvantages of transgenic animals?
Transgenic animals offer scientific and medical benefits but also raise ethical and ecological concerns.
- Advantages: improved disease research, production of therapeutic proteins, enhanced livestock traits.
- Disadvantages: ethical issues, animal welfare concerns, potential environmental risks if released.
10. What is the role of CRISPR in creating transgenic animals?
CRISPR is a precise gene-editing technology used to insert, delete, or modify genes in animal genomes. The CRISPR-Cas9 system works by:
- Targeting a specific DNA sequence.
- Cutting the DNA at that location.
- Allowing insertion of a desired gene or correction of mutations.
