Main article:The process of genetically engineering mammals is a slow, tedious, and expensive process. As with other genetically modified organisms (GMOs), first genetic engineers must isolated the gene they wish to insert into the host organism. This can be taken from a containing the gene. If the chosen gene or the donor organism's has been well studied it may already be accessible from a.
Jun 1, 1991 - This study was performed to assess whether muscle contractile properties are related to the presence of specific myosin heavy chain (MHC). 1,750,254 likes 1,478 talking about this.
The gene is then combined with other genetic elements, including a and region and usually a.A number of techniques are available for. With animals DNA is generally inserted into using, where it can be injected through the cell's directly into the, or through the use of.
The first transgenic animals were produced by injecting viral DNA into embryos and then implanting the embryos in females. It is necessary to ensure that the inserted DNA is present in the. The embryo would develop and it would be hoped that some of the genetic material would be incorporated into the reproductive cells. Then researchers would have to wait until the animal reached breeding age and then offspring would be screened for presence of the gene in every cell, using, and.New technologies are making genetic modifications easier and more precise.
Techniques, which creates and takes advantage on the cells natural repair systems, have been developed to target insertion to exact. Uses artificially engineered that create breaks at specific points. There are four families of engineered nucleases:, (TALENs), and the Cas9-guideRNA system (adapted from ). TALEN and CRISPR are the two most commonly used and each has its own advantages. TALENs have greater target specificity, while CRISPR is easier to design and more efficient.
The development of the system has effectively halved the amount of time needed to develop genetically modified animals. In 1974 created the first GM animal.Humans have animals since around 12,000 BCE, using or artificial selection (as contrasted with ). The process of, in which organisms with desired (and thus with the desired ) are used to breed the next generation and organisms lacking the trait are not bred, is a precursor to the modern concept of genetic modification: 1 Various advancements in allowed humans to directly alter the and therefore genes of organisms. In 1972 created the first molecule when he combined DNA from a with that of the.In 1974 created a by introducing foreign DNA into its embryo, making it the world’s first transgenic animal. However it took another eight years before transgenic mice were developed that passed the to their offspring. Genetically modified mice were created in 1984 that carried cloned, predisposing them to developing cancer.
Mice with genes were created in 1989. The first transgenic livestock were produced in 1985 and the first animal to synthesise transgenic proteins in their milk were mice, engineered to produce human tissue plasminogen activator in 1987.The first genetically modified animal to be commercialised was the, a with a added that allows it to glow in the dark under. It was released to the US market in 2003. The first genetically modified animal to be approved for food use was in 2015. The salmon were transformed with a -regulating gene from a and a promoter from an enabling it to grow year-round instead of only during spring and summer. Some, like the blotched mouse shown, are created through genetic modification techniques like.GM mammals are created for research purposes, production of industrial or therapeutic products, agricultural uses or improving their health. There is also a market for creating genetically modified pets.
Medicine Mammals are the best models for human disease, making genetic engineered ones vital to the discovery and development of cures and treatments for many serious diseases. Knocking out genes responsible for allows researchers to study the mechanism of the disease and to test possible cures. Have been the most common mammals used in, as they are cheap and easy to manipulate. Pigs are also a good target as they have a similar body size and anatomical features, response and diet.
Nonhuman primates are the most similar model organisms to humans, but there is less public acceptance towards using them as research animals. In 2009, scientists announced that they had successfully transferred a gene into a species and produced a stable line of breeding transgenic primates for the first time.
Their first research target for these marmosets was, but they were also considering. Transgenic pig for cheese productionHuman proteins expressed in mammals are more likely to be similar to their natural counterparts than those expressed in plants or microorganisms. Stable expression has been accomplished in sheep, pigs, rats and other animals. In 2009, the first human biological drug produced from such an animal, a., was approved. The drug, is an which reduces the probability of during or was extracted from the goat's milk.
Human is another protein that is used in treating humans with this deficiency. Another area is in creating pigs with greater capacity for. Pigs have been genetically modified so that their organs can no longer carry retroviruses or have modifications to reduce the chance of rejection. Pig lungs from genetically modified pigs are being considered for transplantation into humans. There is even potential to create chimeric pigs that can carry human organs.
Livestock Livestock are modified with the intention of improving economically important traits such as growth-rate, quality of meat, milk composition, disease resistance and survival. Animals have been engineered to grow faster, be healthier and resist diseases. Modifications have also improved the wool production of sheep and udder health of cows.Goats have been genetically engineered to produce milk with strong spiderweb-like silk proteins in their milk. The goat gene sequence has been modified, using fresh umbilical cords taken from kids, in order to code for the human enzyme.
Researchers wanted to alter the milk produced by the goats, to contain lysozyme in order to fight off bacteria causing in humans.Enviropig was a genetically enhanced line of in Canada created with the capability of digesting plant more efficiently than conventional Yorkshire pigs. The A construct consisting of a expressed in the and the gene was introduced into the pig embryo by pronuclear.
This caused the pigs to produce the enzyme, which breaks down the indigestible phosphorus, in their saliva. As a result they excrete 30 to 70% less phosphorus in manure depending upon the age and diet. The lower concentrations of phosphorus in reduces growth, because phosphorus is the for algae. Because algae consume large amounts of oxygen, excessive growth can result in dead zones for fish. Funding for the Enviropig program ended in April 2012, and as no new partners were found the pigs were killed. However, the genetic material will be stored at the Canadian Agricultural Genetics Repository Program.
In 2006, a pig was engineered to produce through the expression of a gene. Herman the Bull on display inIn 1990, the world's first transgenic, Herman the Bull, was developed.
Herman was genetically engineered by micro-injected embyonic cells with the human gene coding for. The changed the law in 1992 to allow Herman to reproduce. Eight calves were born in 1994 and all calves inherited the lactoferrin gene. With subsequent sirings, Herman fathered a total of 83 calves. Dutch law required Herman to be at the conclusion of the.
However the Dutch Agriculture Minister at the time, granted him a reprieve provided he did not have more offspring after public and scientists rallied to his defence. Together with cows named Holly and Belle, he lived out his retirement at, the National Museum of Natural History in Leiden.
On 2 April 2004, Herman was by from the because he suffered from. At the time of his death Herman was one of the oldest bulls in the Netherlands. Herman's hide has been preserved and mounted by and is permanently on display in Naturalis. They say that he represents the start of a new era in the way man deals with nature, an icon of scientific progress, and the subsequent public discussion of these issues.Researchers have developed GM dairy cattle to grow without horns (sometimes referred to as ') which can cause injuries to farmers and other animals. DNA was taken from the genome of cattle, which is known to suppress horn growth, and inserted into cells taken from an elite bull called 'Randy'. Each of the progeny will be a clone of Randy, but without his horns, and their offspring should also be hornless.
In 2011, Chinese scientists generated genetically engineered with genes from human beings to produce milk that would be the same as human breast milk. This could potentially benefit mothers who cannot produce breast milk but want their children to have breast milk rather than formula. The researchers claim these transgenic cows to be identical to regular cows.
Two months later, scientists from presented Rosita, a transgenic cow incorporating two human genes, to produce milk with similar properties as human breast milk. In 2012, researchers from New Zealand also developed a genetically engineered cow that produced allergy-free milk. Research Scientists have genetically engineered several organisms, including some mammals, to include (GFP), for research purposes. GFP and other similar reporting genes allow easy visualisation and localisation of the products of the genetic modification. Fluorescent pigs have been bred to study human organ transplants, regenerating ocular, and other topics.
In 2011 green-fluorescent cats were created to find therapies for and other diseases as (FIV) is related to HIV. Conservation Genetically modification with a has been proposed to conserve in the and to help regulate them in Australia. To protect the Iberian species from viral diseases, the myxoma virus was genetically modified to immunize the rabbits, while in Australia the same myxoma virus was genetically modified to lower fertility in the Australian rabbit population. There have also been suggestions that genetic engineering could be used to bring animals. It involves changing the genome of a close living relative to resemble the extinct one and is currently being attempted with the.
Genes associated with the have been added to the genome of an, although the lead researcher says he has no intention of using live elephants. Humans , uses genetically modified viruses to deliver genes which can cure disease in humans. Although gene therapy is still relatively new, it has had some successes.
It has been used to treat such as,. Treatments are also being developed for a range of other currently incurable diseases, such as,. These treatments only affect, meaning any changes would not be inheritable. Gene therapy results in any change being inheritable, which has raised concerns within the scientific community.
In 2015, CRISPR was used to edit the DNA of non-viable. In November 2018, announced that he had of two human embryos, to attempt to disable the gene, which codes for a receptor that uses to enter cells.
He said that twin girls, had been born a few weeks earlier and that they carried functional copies of CCR5 along with disabled CCR5 and were still vulnerable to HIV. The work was widely condemned as unethical, dangerous, and premature. Main article:Genetically modified fish are used for scientific research, as pets and as a food source.
Is a growing industry, currently providing over half the consumed fish worldwide. Through genetic engineering It is possible to increase growth rates, reduce food intake, remove allergenic properties, increase cold tolerance and provide disease resistance.Detecting pollution Fish can also be used to detect aquatic pollution or function as bioreactors. Several groups have been developing to detect pollution by attaching fluorescent proteins to genes activated by the presence of pollutants. The fish will then glow and can be used as environmental sensors. Pets The is a brand of genetically modified fluorescent with bright red, green, and orange fluorescent color.
It was originally developed by one of the groups to detect pollution, but is now part of the ornamental fish trade, becoming the first genetically modified animal to become publicly available as a pet when it was introduced for sale in 2003. Research GM fish are widely used in basic research in genetics and development. Two species of fish, zebrafish and, are most commonly modified because they have optically clear (membranes in the egg), rapidly develop, and the 1-cell embryo is easy to see and microinject with transgenic DNA. Zebrafish are model organisms for developmental processes, genetics, behaviour, disease mechanisms and toxicity testing.
Their transparency allows researchers to observe developmental stages, intestinal functions and tumour growth. The generation of transgenic protocols (whole organism, cell or tissue specific, tagged with reporter genes) has increased the level of information gained by studying these fish. Growth GM fish have been developed with promoters driving an over-production of 'all fish' for use in the industry to increase the speed of development and potentially reduce fishing pressure on wild stocks.
This has resulted in dramatic growth enhancement in several species, including, and.have produced a salmon that can mature in half the time as wild salmon. The fish is an Atlantic salmon with a ( Oncorhynchus tshawytscha) gene inserted. This allows the fish to produce growth hormones all year round compared to the wild-type fish that produces the hormone for only part of the year. The fish also has a second gene inserted from the eel-like that acts like an 'on' switch for the hormone.
Pout also have in their blood, which allow the GM salmon to survive near-freezing waters and continue their development. The wild-type salmon takes 24 to 30 months to reach market size (4–6 kg) whereas the producers of the GM salmon say it requires only 18 months for the GM fish to achieve this.
In November 2015, the FDA of the USA approved the for commercial production, sale and consumption, the first non-plant GMO food to be commerialised.say that to prevent the genetically modified fish inadvertently breeding with wild salmon, all the fish will be female and reproductively sterile, although a small percentage of the females may remain fertile. Some opponents of the GM salmon have dubbed it the 'Frankenfish'.
See also: Research In biological research, transgenic fruit flies ( ) are used to study the effects of genetic changes on development. Fruit flies are often preferred over other animals due to their short life cycle and low maintenance requirements. It also has a relatively simple genome compared to many, with typically only one copy of each gene, making phenotypic analysis easy. Drosophila have been used to study genetics and inheritance, embryonic development, learning, behavior, and aging. (particularly P elements) are well developed in Drosophila and provided an early method to add transgenes to their genome, although this has been taken over by more modern gene-editing techniques. Population control Due to their significance to human health, scientists are looking at ways to control mosquitoes through genetic engineering.
Malaria-resistant mosquitoes have been developed in the laboratory. By inserting a gene that reduces the development of the malaria parasite and then use to rapidly spread that gene throughout the male population (known as a ). This has been taken further by swapping it for a lethal gene. In trials the populations of mosquitoes, the single most important carrier of dengue fever and Zika virus, were reduced by between 80% and by 90%.
Another approach is to use the, whereby males genetically engineered to be sterile out compete viable males, to reduce population numbers.Other insect pests that make attractive targets are. Cause US$4 to $5 billion of damage a year worldwide.
The approach is similar to the mosquitoes, where males transformed with a gene that prevents females from reaching maturity will be released. They underwent field trials in 2017.
Genetically modified moths have previously been released in field trials. A strain of that were sterilised with radiation were genetically engineered to express a making it easier for researchers to monitor them. Industry Silkworm, the larvae stage of, is an economically important insect in. Scientists are developing strategies to enhance silk quality and quantity. There is also potential to use the silk producing machinery to make other valuable proteins. Proteins expressed by silkworms include;, mouse. Silkworms have been created that produce, a stronger but extremely difficult to harvest silk, and even novel silks.
Birds Attempts to produce genetically modified birds began before 1980. Chickens have been genetically modified for a variety of purposes. This includes studying, preventing the transmission of and providing evolutionary insights using to recreate dinosaur-like phenotypes.
A GM chicken that produces the drug, an enzyme that treats a rare condition, in its egg passed regulatory approval in 2015. Disease control One potential use of GM birds could be to reduce the spread of avian disease. Researchers at have produced a strain of GM chickens ( Gallus gallus domesticus) that does not transmit to other birds; however, these birds are still susceptible to contracting it. The genetic modification is an molecule that prevents the virus reproduction by mimicking the region of the flu virus genome that controls replication. It is referred to as a 'decoy' because it diverts the flu virus enzyme, the, from functions that are required for virus replication.
Evolutionary insights A team of geneticists led by paleontologist is seeking to modify a chicken to express several features present in ancestral but absent in modern birds, such as teeth and a long tail, creating what has been dubbed a 'chickenosaurus'. Parallel projects have produced chicken embryos expressing dinosaur-like skull, leg, and foot anatomy.Amphibians Genetically modified frogs, in particular and, are used in. GM frogs can also being used as pollution sensors, especially for. There are proposals to use genetic engineering to control. Nematodes The is one of the major model organisms for researching.
(RNAi) was discovered in C elegans and could be induced by simply feeding them bacteria modified to express. It is also relatively easy to produce stable transgenic nemotodes and this along with RNAi are the major tools used in studying their genes. The most common use of transgenic nematodes has been studying gene expression and localisation by attaching reporter genes. Transgenes can also be combined with RNAi to rescue phenotypes, altered to study gene function, imaged in real time as the cells develop or used to control expression for different tissues or developmental stages. Transgenic nematodes have been used to study viruses, toxicology, and diseases and to detect environmental pollutants.
Other Systems have been developed to create transgenic organisms in a wide variety of other animals. The gene responsible for in has been found and used to engineer, a rare delicacy. The technology also opens the way to investigate the genes responsible for some of the cucumbers more unusual traits, including in summer, their intestines, and dissolving their bodies upon death. Have the ability to regenerate themselves from a single cell. Until 2017 there was no effective way to transform them, which hampered research.
By using microinjection and radiation scientist have now created the first genetically modified flatworms. The, a marine, has been modified. It is of interest due to its reproductive cycle being synchronised with lunar phases, regeneration capacity and slow evolution rate.
Such as and the sea anemone are attractive model organisms to study the of and certain developmental processes. Other organisms that have been genetically modified include,. References.
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