Objective:
Explain the processes involved in cloning and producing transgenic animals

Genetic modification
Genetic modification is the change of the genes of a living organism such as a plant or animal using modern techniques of biotechnology. DNA sequencing of entire genomes has been instrumental in the development of new genetically modified animals.

Purpose of genetic modification of animals
The main purposes of using genetic modification of animals are:

improving food-producing animals and agricultural plants
Development of new of plants and animals through natural selection and evolution is a slow process that takes millions of years. Ancient people learned to improve the speed through artificial selection. As the demand for food increases with world’s population growing, genetic modification of animals and plants became the most efficient way of increasing agricultural production. Genetically modified animals and plants developed in a matter of a few decades produce more and better milk, meat, fiber, they became more resistant to diseases and droughts.

development of treatments for human disease
With genetic modification of animals, production of certain important human proteins such as insulin has become a reality. Scientists have seen success with the use of some animal tissues, bones, and joints in humans. Research continues in the field of skin and organ tissue transplantations. Pigs are commonly used in this research because of their similarities to humans. Pigs producing ‘humanized’ skin, for example, can be used as a source for skin restoration in humans. Animals such as mice are genetically modified to help understanding and developing treatments for human and animal diseases.

production of pharmaceuticals
Genetic engineering has allowed production of certain hormones (insulin, human growth hormone, bovine and porcine somatotropin and other). Current research has shown the possibility of genetically modifying sheep or cattle to produce human proteins in their milk.

Benefits
Genetic modification of animals has shown several benefits. These include increased resistance to disease and parasites, increased productivity and improved hardiness to weather factors. Other benefits involve animal products, such as increased yields of meat, eggs, and milk.

Cloning animals
There are two main types of animal cloning: reproductive cloning and cloning through recombinant DNA technology

Reproductive cloning is a common process very well known for creating an exact genetic match of an animal. In 1996, Dolly the sheep was produced by reproductive cloning and was the first animal to be cloned from adult DNA. Since Dolly, advancements have been made in the process of cloning, and several other animals have been cloned. The reproductive cloning process begins with the transfer of genetic material from the nucleus of a donor adult cell to an egg whose nucleus has been removed. The egg is stimulated with chemicals or electrical current to promote cell division. As the cloned embryo divides in a test tube and reaches a suitable developmental stage, it is transplanted into a female host. The female carries the cloned embryo until birth.

Recombinant DNA (rDNA) technology is the process that occurs when fragments of DNA from two different species are joined in vitro to form a single DNA molecule. Usually, the DNA from one species is incorporated in a plasmid that is a circular DNA replicating independently on the bacterial genomic DNA. A plasmid is then amplified inside the bacteria, isolated and inserted into the genome of embryonic stem (ES) cells to be altered, allowing the DNA of two different organisms to be combined in a single cell. Then the cell is injected into an embryo at early stage of development and the embryo is then implanted in foster mother uterus to produce a chimeric transgenic animal.

Transgenic animals
A transgenic animal is an animal that has incorporated a foreign gene into its cells. The animal can pass this transgene (altered gene) on to its offspring. Every cell within the transgenic animal contains a copy of this transgene. Several different methods can be used to produce transgenic animals.

Microinjection is the most common technique used to produce transgenic animals. Injecting DNA into a cell using a fine-diameter glass needle and a microscope constitutes microinjection. During this operation, the chosen gene from the same or a different species is directly microinjected into the ovum. The injected DNA integrates randomly with nuclear DNA and its expression is possible only when the foreign DNA is attached to a suitable promoter DNA sequence. There are many examples where different types of animal cells have been microinjected and successfully transferred.

Once a manipulated fertilized ovum develops to a specific embryonic phase, it is transferred to the oviduct of a recipient female. The embryo will develop just as a normal embryo and is typically carried full term.

Marker gene is a gene that helps easily identify animals which successfully incorporated transgene. With the use of marker genes, it is possible not only to determine whether a transgenic animal has received the desired DNA but also whether the genes in the DNA are being expressed. The genetic markers help identifying the location of incorporated DNA in the host genome. The expression of a marker gene can be visualised with staining selected tissues or whole embryos. Polymerase chain reaction (PCR) followed by gel electrophoresis is a technique of choice due to its speed and sensitivity.

Improving domestic animals
Currently the U.S. Meat Animal Research Center (USMARC) has developed DNA markers to identify all cattle in the United States. This method allows improved animal traceability and verification of disease sources. DNA testing also allows producers to base their management and selection process on genetic potential of identified animals.

DNA testing can determine the presence of certain traits and proteins. A common method used in the beef cattle industry involves the presence of the tenderness or marbling genes. This information allows producers to enhance the production of tender meat and meat with optimal marbling. It also allows producers to produce a consistent product.

Xenotransplantation
Xenotransplantation is the transfer of living cells, tissues, or whole organs from one species to another. People who need a kidney for transplantation often chose to use a pig kidney even if that organ was obtained from a genetically engineered pig.

Summary:
With the new technology of genome sequencing and mapping, genetic modification holds the potential for improvements in livestock. The main purposes for using genetic modification of animals are increased production of food-producing animals, treatments for human disease, and production of pharmaceuticals.

Did you know?
1. Identical twins are clones that occurred naturally.
2. Many animal cloning technologies are used for clinical reproductive procedures.
3. The process of cloning in the lab is a very complex procedure.

Checking what you have learned
1. What are the main purposes of genetic modification in animals?
2. What is a transgenic animal?
3. What are the steps involved in cloning an animal through reproductive cloning?
4. What are the steps involved in producing a transgenic animal?
5. How are marker genes used?

1. The first lesson of success can be learned from the woodpecker. Yes, the woodpecker! It’s called “The lesson of focus”.

Woodpecker is much smarter than we are. Yes, he beats his head against a tree, but he does it so very successfully. His goal is always realistic – he never tries to split the tree in half and in a single motion, as many of us do. Woodpecker stays focused. He never knocks at all sides of a tree at the same time. He focuses his effort on a single point, slowly getting to his worm. What we always want is not a worm but at least a snake. We want to find the snake under lose leaves sprinkled on the ground leaving hard to reach places unchecked.

2. The second lesson can be learned from the success of the fish. It’s called “stream lesson”.

The fish always swims against the current and rarely downstream. This is crazy! Right? Why would they complicate their lives when they could use the force of the current to move down the stream? In fact, moving upstream allows more water to pass through their gills. It brings more oxygen and food. So life of the fish swimming upstream is several times richer. In contrast to the fish, we always try to go with the flow or ‘swim in the stagnant water’. As a result, instead of 40 years of experience, we repeat a one-year experience 40 times. We do not want to leave our comfort zone, and then wonder why our life was so dull and unsuccessful. We want to win the lottery of life, not even buying a lottery ticket.

3. The third lesson of success you can learn from lion cubs. This lesson is called – “soil you face with blood”.

Lion cubs know how to learn. And they do not learn from textbooks but rather from the older, more experienced lions. They know exactly – in order to learn how to hunt, they should soil their muzzles with blood. We are even afraid to soil our hands. We learn hunting as we sit in a classroom and look at the board dressed teacher-hare. Or even worse, – we lock ourselves in a room and study ourselves, but when it comes to real hunting, we do not know how, we are afraid of the smell of blood.

4. We can learn the fourth lesson of success from the dogs. This skill is called “wiggle your social tail first”.

In the 21st century, is not important what you do yourself. What is important is how efficiently you motivate others. A perfect example of this is a dog. The dog does not think: “First, you bring me home, feed and wash me and then I’ll wiggle my tail and play with you.” No! Dog first shows his good feelings, and only then gets what it wants in return. Dogs do not force you to do anything, they make you want to do everything for them.

5. Snake gives us the fifth lesson of success. The lesson is called “do not whine”.

Snake does not think: “I have no arms or legs, I have poor eyesight, I was not born in this country, and my parents did not care about me since I had hatched.” Snake efficiently uses what it has. We even are scared of the “disabled animal”. If snake does not like something, it just changes the skin and creeps forward without regrets.

Most people would offer help to a friend in need. Is altruism unique to humans or is it a common trend in other animals? A new study describes altruistic behavior in rats and finds rats empathetic to each other.

In the study, rats were allowed to live in one cage to get used to each other, then one of the rats was placed in a narrow clear plastic tube with a small door that could be opened only from outside. The second rat could see the trapped pall and hear its unhappy calls for help. The free rat immediately starts sniffing the trap, biting it, climbing on it making clear it wants to get the trapped rat out. Once the free rat saw the tail of trapped rat poking through the holes in the trap and grabbed the tail and pulled on it trying to get the pal out. Eventually, the free rat would accidentally push the button and open the trap door releasing its buddy. The researches repeated this experiment many times. The free rat would quickly learn to open the trap door on purpose but only did it for pal and not if the trap was empty or contained a toy rat. They did it even when opening the door released their pal into a separate cage. So it was not just that the free rat wanted a playmate. The free rats seemed to just want to help. The results are reported in the journal Science.

Why rats do that? Scientists could not simply ask rats. All they can do is to design experiments to get as clear and as easy to interpret answer as possible. Rats really care about food and they love chocolate. So scientists put two traps inside the plastic box. Inside one trap, they put chocolate and inside the other – distressed rat. The free rat quickly opens both traps in no particular order. What it tells scientists is that liberating a trapped friend has the same value to free rat as getting chocolate. Even though the free rat could have just gobbled the chocolate first and then release the pal, it instead chooses to share the chocolate with fellow rats.

People often think that these social abilities such as compassion and altruism are unique to humans and apes as if they just appeared without preceding evolutionary events. This new study is a dramatic confirmation that not only humans can feel pain of friends and try to help. It looks like the roots of empathy and altruism go way back. This study gives scientists a new tool to look in depth of the phenomenon of empathy, altruism, love and abstract thinking in general.

It appears that altruism was not an accident, it was rather evolutionary beneficial. Human evolution has proven that it is easier to survive living in larger communities helping each other and sharing food and resources. Those who did not fill helping each other did not survive at harder times and did not pass their genes to future generations. That is how genes of altruism have been accumulated and fixed in human populations. That is how altruism became a norm of humane behavior.