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Genetically modified fish (GM fish) are organisms from the taxonomic clade which includes the classes Agnatha (jawless fish), Chondrichthyes (cartilaginous fish) and Osteichthyes (bony fish) whose genetic material (DNA) has been altered using genetic engineering techniques. In most cases, the aim is to introduce a new trait to the fish which does not occur naturally in the species, i.e. transgenesis.
GM fish are used in scientific research and kept as pets. They are being developed as environmental pollutant sentinels and for use in aquaculture food production. In 2015, the AquAdvantage salmon was approved by the US Food and Drug Administration (FDA) for commercial production, sale and consumption, [1] making it the first genetically modified animal to be approved for human consumption. Some GM fish that have been created have promoters driving an over-production of "all fish" growth hormone. This results in dramatic growth enhancement in several species, including salmonids, [2] carps [3] and tilapias. [4] [5]
Critics have objected to GM fish on several grounds, including ecological concerns, animal welfare concerns and with respect to whether using them as food is safe and whether GM fish are needed to help address the world's food needs.
The first transgenic fish were produced in China in 1985. [6] As of 2013, approximately 50 species of fish have been subject to genetic modification. This has resulted in more than 400 fish/trait combinations. Most of the modifications have been conducted on food species, such as Atlantic salmon (Salmo salar), tilapia (genus) and common carp (Cyprinus carpio). [7]
Generally, genetic modification entails manipulation of DNA. The process is known as cisgenesis when a gene is transferred between organisms that could be conventionally bred, or transgenesis when a gene from one species is added to a different species. Gene transfer into the genome of the desired organism, as for fish in this case, requires a vector like a lentivirus or mechanical/physical insertion of the altered genes into the nucleus of the host by means of a micro syringe or a gene gun. [8]
Transgenic fish are used in research covering five broad areas [6]
Most GM fish are used in basic research in genetics and development. Two species of fish, zebrafish (Danio rerio) and medaka (Japanese rice fish, Oryzias latipes), are most commonly modified because they have optically clear chorions (shells), develop rapidly, the 1-cell embryo is easy to see and micro-inject with transgenic DNA, and zebrafish have the capability of regenerating their organ tissues. [9] They are also used in drug discovery. [10] GM zebrafish are being explored for benefits of unlocking human organ tissue diseases and failure mysteries. For instance, zebrafish are used to understand heart tissue repair and regeneration in efforts to study and discover cures for cardiovascular diseases. [11]
Transgenic rainbow trout (Oncorhynchus mykiss) have been developed to study muscle development. The introduced transgene causes green fluorescence to appear in fast twitch muscle fibres early in development which persist throughout life. It has been suggested the fish might be used as indicators of aquatic pollutants or other factors which influence development. [12]
In intensive fish farming, the fish are kept at high stocking densities. This means they suffer from frequent transmission of contagious diseases, a problem which is being addressed by GM research. Grass carp (Ctenopharyngodon idella) have been modified with a transgene coding for human lactoferrin, which doubles their survival rate relative to control fish after exposure to Aeromonas bacteria and Grass carp hemorrhage virus. Cecropin has been used in channel catfish to enhance their protection against several pathogenic bacteria by 2–4 times. [13]
GloFish is a patented [14] technology which allows GM fish (tetra, barb, zebrafish) to express jellyfish and sea coral proteins [6] [15] giving the fish bright red, green or orange fluorescent colors when viewed in ultraviolet light. Although the fish were originally created and patented for scientific research at the National University of Singapore, a Texas company, Yorktown Technologies, obtained the rights to market the fish as pets. [15] They became the first genetically modified animal to become publicly available as a pet when introduced for commercial in 2003. [16] They were quickly banned for sale in California; however, they are now on shelves once again in this state. [17] As of 2013, Glofish are only sold in the US. [18]
Other transgenic lines of pet fish include Medaka which remain transparent throughout their lives and pink body color transgenic angelfish ( Pterophyllum scalare ) and lionhead fish expressing the Acropora coral ( Acroporo millepora ) red fluorescent protein. [19]
The ocean pout type III antifreeze protein transgene has been successfully micro-injected and expressed in goldfish. The transgenic goldfish showed higher cold tolerance compared with controls. [20]
One area of intensive research with GM fish has aimed to increase food production by modifying the expression of growth hormone (GH). The relative increases in growth differ between species. [21] (Figure 1) [22] They range from a doubling in weight, to some fish that are almost 100 times heavier than the wild-type at a comparable age. [13] This research area has resulted in dramatic growth enhancement in several species, including salmon, [23] trout [24] and tilapia. [25] Other sources indicate an 11-fold and 30-fold increase in growth of salmon and mud loach, respectively, compared to wild-type fish. [6] [26] Transgenic fish development has reached the stage where several species are ready to be marketed in different countries, for example, GM tilapia in Cuba, GM carp in the People's Republic of China, and GM salmon in the US and Canada. [27] In 2014, it was reported that applications for the approval of transgenic fish as food had been made in Canada, China, Cuba and the United States. [6]
Over-production of GH from the pituitary gland increases growth rate mainly by an increase in food consumption by the fish, but also by a 10 to 15% increase in feed conversion efficiency. [28]
Another approach to increasing meat production in GM fish is "double muscling". This results in a phenotype similar to that of Belgian Blue cattle in rainbow trout. It is achieved by using transgenes expressing follistatin, which inhibits myostatin, and the development of two muscle layers. [13]
In November 2015, the FDA of the USA approved the AquAdvantage salmon created by AquaBounty for commercial production, sale and consumption. [1] [29] It is the first genetically modified animal to be approved for human consumption. The fish is essentially an Atlantic salmon with a single gene complex inserted: a growth hormone regulating gene from a Chinook salmon with a promoter sequence from an ocean pout. This permits the GM salmon to produce GH year round rather than pausing for part of the year as do wild-type Atlantic salmon. [30] The wild-type salmon takes 24 to 30 months to reach market size (4–6 kg) whereas the GM salmon require 18 months for the GM fish to achieve this. [31] [32] [33] [13] AquaBounty argue that their GM salmon can be grown nearer to end-markets with greater efficiency (they require 25% less feed to achieve market weight [34] ) than the Atlantic salmon which are currently reared in remote coastal fish farms, thereby making it better for the environment, with recycled waste and lower transport costs. [35]
To prevent the genetically modified fish inadvertently breeding with wild salmon, all the fish raised for food are females, triploid, and 99% are reproductively sterile. [33] [30] The fish are raised in a facility in Panama with physical barriers and geographical containment such as river and ocean temperatures too high to support salmon survival to prevent escape. [36] The FDA has determined AquAdvantage would not have a significant effect on the environment in the United States. [36] [37] A fish farm is also being readied in Indiana where the FDA has approved importation of salmon eggs. [38] As of August 2017, GMO salmon is being sold in Canada. [39] Sales in the US began in May 2021. [40]
Several research groups have been developing GM zebrafish to detect aquatic pollution. [41] The laboratory that developed the GloFish originally intended them to change color in the presence of pollutants, as environmental sentinels. [42] [43] Teams at the University of Cincinnati and Tulane University have been developing GM fish for the same purpose. [44] [45] [46]
Several transgenic methods have been used to introduce target DNA into zebrafish for environmental monitoring, including micro-injection, electroporation, particle gun bombardment, liposome-mediated gene transfer, and sperm-mediated gene transfer. Micro-injection is the most commonly used method to produce transgenic zebrafish as this produces the highest survival rate. [47]
The regulation of genetic engineering concerns the approaches taken by governments to assess and manage the risks associated with the development and release of genetically modified crops. There are differences in the regulation of GMOs between countries, with some of the most marked differences occurring between the US and Europe. Regulation varies in a given country depending on the intended use of the products of the genetic engineering. For example, a fish not intended for food use is generally not reviewed by authorities responsible for food safety.
The US FDA guidelines for evaluating transgenic animals define transgenic constructs as "drugs" regulated under the animal drug provisions of the Federal Food and Cosmetic Act. This classification is important for several reasons, including that it places all GM food animal permits under the jurisdiction of the FDA's Center for Veterinary Medicine (CVM) and imposes limits on what information the FDA can release to the public, and furthermore, it avoids a more open food safety review process. [48]
The US states of Washington and Maine have imposed permanent bans on the production of transgenic fish. [48]
Critics have objected to use of genetic engineering per se on several grounds, including ethical concerns, ecological concerns (especially about gene flow), and economic concerns raised by the fact GM techniques and GM organisms are subject to intellectual property law. GMOs also are involved in controversies over GM food with respect to whether using GM fish as food is safe, whether it would exacerbate or cause fish allergies, whether it should be labeled, and whether GM fish and crops are needed to address the world's food needs. These controversies have led to litigation, international trade disputes, and protests, and to restrictive regulation of commercial products in most countries.
There is much doubt among the public about genetically modified animals in general. [49] It is believed that the acceptance of GM fish by the general public is the lowest of all GM animals used for food and pharmaceuticals. [50]
In transgenic fast-growing fish genetically modified for growth hormone, the mosaic founder fish vary greatly in their growth rate, reflecting the highly variable proportion and distribution of transgenic cells in their bodies. Fish with these high growth rates (and their progeny) sometimes develop a morphological abnormality similar to acromegaly in humans, exhibiting an enlarged head relative to the body and a bulging operculum. This becomes progressively worse as the fish ages. It can interfere with feeding and may ultimately cause death. According to a study commissioned by Compassion in World Farming, the abnormalities are probably a direct consequence of growth hormone over-expression and have been reported in GM coho salmon, rainbow trout, common carp, channel catfish and loach, but to a lesser extent in Nile tilapia. [51] [ unreliable source? ]
In GM coho salmon (Oncorhynchus kisutch) there are morphological changes and changed allometry that lead to reduced swimming abilities. They also exhibit abnormal behaviour such as increased levels of activity with respect to feed-intake and swimming. [27] Several other transgenic fish show decreased swimming ability, likely due to body shape and muscle structure. [28]
Genetically modified triploid fish are more susceptible to temperature stress, have a higher incidence of deformities (e.g. abnormalities in the eye and lower jaw [52] ), and are less aggressive than diploids. [53] [54] Other welfare concerns of GM fish include increased stress under oxygen-deprived conditions caused by increased need for oxygen. [27] It has been shown that deaths due to low levels of oxygen (hypoxia) in coho salmon are most pronounced in transgenics. [55] It has been suggested the increased sensitivity to hypoxia is caused by the insertion of the extra set of chromosomes requiring a larger nucleus which thereby causes a larger cell overall and a reduction in the surface area to volume ratio of the cell.
Transgenic fish are usually developed in strains of near-wild origin. These have an excellent capacity for interbreeding with themselves or wild relatives and therefore possess a significant possibility for establishing themselves in nature should they escape biotic or abiotic containment measures. [21]
A wide range of concerns about the consequences of genetically modified fish escaping have been expressed. For polyploids, these include the degree of sterility, interference with spawning, competing with resources without contributing to subsequent generations. For transgenics, the concerns include characteristics of the genotype, the function of the gene, the type of the gene, potential for causing pleiotropic effects, potential for interacting with the remainder of the genome, stability of the construct, ability of the DNA construct to transpose within or between genomes. [56]
One study, using relevant life history data from the Japanese medaka ( Oryzias latipes ) predicts that a transgene introduced into a natural population by a small number of transgenic fish will spread as a result of enhanced mating advantage, but the reduced viability of offspring will cause eventual local extinction of both populations. [57] GM coho salmon show greater risk-taking behaviour and better use of limited food than wild-type fish.
Transgenic coho salmon have enhanced feeding capacity and growth, which can result in a considerably larger body size (>7-fold) compared to non-transgenic salmon. When transgenic and non-transgenic salmon in the same enclosure compete for different levels of food, transgenic individuals consistently outgrow non-transgenic individuals. When food abundance is low, dominant individuals emerge, invariably transgenic, that show strong agonistic and cannibalistic behavior to cohorts and dominate the acquisition of limited food resources. When food availability is low, all groups containing transgenic salmon experience population crashes or complete extinctions, whereas groups containing only non-transgenic salmon have good (72%) survival rates. [58] This has led to the suggestion that these GM fish will survive better than the wild-type when conditions are very poor. [28] [59]
Successful artificial transgenic hybridization between two species of loach (genus Misgurnus) has been reported, yet these species are not known to hybridize naturally. [60]
GloFish were not considered as an environmental threat because they were less fit than normal zebrafish which are unable to establish themselves in the wild in the US. [6]
The FDA has said the AquAdvantage Salmon can be safely contained in land-based tanks with little risk of escape into the wild; [35] however, Joe Perry, former chair of the GM panel of the European Food Safety Authority, has been quoted as saying "There remain legitimate ecological concerns over the possible consequences if these GM salmon escape to the wild and reproduce, despite FDA assurances over containment and sterility, neither of which can be guaranteed". [35]
AquaBounty indicates their GM salmon can not interbreed with wild fish because they are triploid which makes them sterile. [32] The possibility of fertile triploids is one of the major short-falls of triploidy being used as a means of bio-containment for transgenic fish. [61] However, it is estimated that 1.1% of eggs remain diploid, and therefore capable of breeding, despite the triploidy process. [62] Others have claimed the sterility process has a failure rate of 5%. With around a million fish in each of the 3,000 Atlantic sites a single failure could result in the release of 1,100 to 5,000 genetically altered fish capable of reproducing. [63] [34] Large scale trials using normal pressure, high pressure, or high pressure plus aged eggs for transgenic coho salmon, give triploidy frequencies of only 99.8%, 97.6%, and 97.0%, respectively. [64] AquaBounty also emphasizes that their GM salmon would not survive wild conditions due to the geographical locations where their research is conducted, as well as the locations of their farms. [32]
The GH transgene can be transmitted via hybridization of GM AquAdvantage Salmon and the closely related wild brown trout (Salmo trutta). Transgenic hybrids are viable and grow more rapidly than transgenic salmon and other wild-type crosses in conditions emulating a hatchery. In stream mesocosms designed to simulate natural conditions, transgenic hybrids express competitive dominance and suppress the growth of transgenic and non-transgenic salmon by 82% and 54%, respectively. [65] Natural levels of hybridization between these two species can be as high as 41%. [65] Researchers examining this possibility concluded "Ultimately, we suggest that hybridization of transgenic fishes with closely related species represents potential ecological risks for wild populations and a possible route for introgression of a transgene, however low the likelihood, into a new species in nature." [60]
An article in Slate Magazine in December 2012 by Jon Entine, Director of the Genetic Literacy Project, criticized the Obama administration for preventing the publication of the environmental assessment (EA) of the AquAdvantage Salmon, which was completed in April 2012 and which concluded that "the salmon is safe to eat and poses no serious environmental hazards." [66] The Slate article said that the publication of the report was stopped "after meetings with the White House, which was debating the political implications of approving the GM salmon, a move likely to infuriate a portion of its base". [66] Within days of the article's publication and less than two months after the election, the FDA released the draft EA and opened the comment period. [67]
The zebrafish is a freshwater fish belonging to the minnow family (Cyprinidae) of the order Cypriniformes. Native to South Asia, it is a popular aquarium fish, frequently sold under the trade name zebra danio.
A genetically modified organism (GMO) is any organism whose genetic material has been altered using genetic engineering techniques. The exact definition of a genetically modified organism and what constitutes genetic engineering varies, with the most common being an organism altered in a way that "does not occur naturally by mating and/or natural recombination". A wide variety of organisms have been genetically modified (GM), including animals, plants, and microorganisms.
Genetic engineering, also called genetic modification or genetic manipulation, is the modification and manipulation of an organism's genes using technology. It is a set of technologies used to change the genetic makeup of cells, including the transfer of genes within and across species boundaries to produce improved or novel organisms.
Fish farming or pisciculture involves commercial breeding of fish, most often for food, in fish tanks or artificial enclosures such as fish ponds. It is a particular type of aquaculture, which is the controlled cultivation and harvesting of aquatic animals such as fish, crustaceans, molluscs and so on, in natural or pseudo-natural environments. A facility that releases juvenile fish into the wild for recreational fishing or to supplement a species' natural numbers is generally referred to as a fish hatchery. Worldwide, the most important fish species produced in fish farming are carp, catfish, salmon and tilapia.
Genetically modified foods, also known as genetically engineered foods, or bioengineered foods are foods produced from organisms that have had changes introduced into their DNA using various methods of genetic engineering. Genetic engineering techniques allow for the introduction of new traits as well as greater control over traits when compared to previous methods, such as selective breeding and mutation breeding.
The GloFish is a patented and trademarked brand of fluorescently colored genetically modified aquarium fish. They have been created from several different species of fish: zebrafish were the first GloFish available in pet stores, and recently the black tetra, tiger barb, rainbow shark, Siamese fighting fish, X-ray tetra, and most recently bronze corydoras have been added to the lineup. They are sold in many colors, trademarked as "Starfire Red", "Moonrise Pink", "Sunburst Orange", "Electric Green", "Cosmic Blue", and "Galactic Purple", although not all species are available in all colors. Although not originally developed for the ornamental fish trade, it is one of the first genetically modified animals to become publicly available. The rights to GloFish are owned by Spectrum Brands, Inc., which purchased GloFish from Yorktown Technologies, the original developer of GloFish, in May 2017.
A transgene is a gene that has been transferred naturally, or by any of a number of genetic engineering techniques, from one organism to another. The introduction of a transgene, in a process known as transgenesis, has the potential to change the phenotype of an organism. Transgene describes a segment of DNA containing a gene sequence that has been isolated from one organism and is introduced into a different organism. This non-native segment of DNA may either retain the ability to produce RNA or protein in the transgenic organism or alter the normal function of the transgenic organism's genetic code. In general, the DNA is incorporated into the organism's germ line. For example, in higher vertebrates this can be accomplished by injecting the foreign DNA into the nucleus of a fertilized ovum. This technique is routinely used to introduce human disease genes or other genes of interest into strains of laboratory mice to study the function or pathology involved with that particular gene.
Since the advent of genetic engineering in the 1970s, concerns have been raised about the dangers of the technology. Laws, regulations, and treaties were created in the years following to contain genetically modified organisms and prevent their escape. Nevertheless, there are several examples of failure to keep GM crops separate from conventional ones.
Genetically modified plants have been engineered for scientific research, to create new colours in plants, deliver vaccines, and to create enhanced crops. Plant genomes can be engineered by physical methods or by use of Agrobacterium for the delivery of sequences hosted in T-DNA binary vectors. Many plant cells are pluripotent, meaning that a single cell from a mature plant can be harvested and then under the right conditions form a new plant. This ability is most often taken advantage by genetic engineers through selecting cells that can successfully be transformed into an adult plant which can then be grown into multiple new plants containing transgene in every cell through a process known as tissue culture.
Genetic pollution is a term for uncontrolled gene flow into wild populations. It is defined as "the dispersal of contaminated altered genes from genetically engineered organisms to natural organisms, esp. by cross-pollination", but has come to be used in some broader ways. It is related to the population genetics concept of gene flow, and genetic rescue, which is genetic material intentionally introduced to increase the fitness of a population. It is called genetic pollution when it negatively impacts the fitness of a population, such as through outbreeding depression and the introduction of unwanted phenotypes which can lead to extinction.
The salmon louse is a species of copepod in the genus Lepeophtheirus. It is a sea louse, a parasite living mostly on salmon, particularly on Pacific and Atlantic salmon and sea trout, but is also sometimes found on the three-spined stickleback. It feeds on the mucus, skin and blood of the fish. Once detached, they can be blown by wind across the surface of the sea, like plankton. When they encounter a suitable marine fish host, they adhere themselves to the skin, fins, or gills of the fish, and feed on the mucus or skin. Sea lice only affect fish and are not harmful to humans.
Genetically modified animals are animals that have been genetically modified for a variety of purposes including producing drugs, enhancing yields, increasing resistance to disease, etc. The vast majority of genetically modified animals are at the research stage while the number close to entering the market remains small.
The aquaculture of salmonids is the farming and harvesting of salmonid fish under controlled conditions for both commercial and recreational purposes. Salmonids, along with carp and tilapia, are the three most important fish groups in aquaculture. The most commonly commercially farmed salmonid is the Atlantic salmon.
The United States is the largest grower of commercial crops that have been genetically engineered in the world, but not without domestic and international opposition.
AquAdvantage salmon is a genetically engineered (GE) fish, a GE Atlantic salmon developed by AquaBounty Technologies in 1989. The typical growth hormone-regulating gene in the Atlantic salmon was replaced with the growth hormone-regulating gene from Pacific Chinook salmon, with a promoter sequence from ocean pout. This gene enables GM salmon to grow year-round instead of only during spring and summer.
AquaBounty Technologies is a biotechnology and aquaculture company based in Maynard, Massachusetts, United States. The company is notable for its research and development of genetically modified fish. It aims to create products that aim to increase the productivity of aquaculture. As of 2020, sale of salmon has been approved in Canada and the United States.
Genetic engineering is the science of manipulating genetic material of an organism. The concept of genetic engineering was first proposed by Nikolay Timofeev-Ressovsky in 1934. The first artificial genetic modification accomplished using biotechnology was transgenesis, the process of transferring genes from one organism to another, first accomplished by Herbert Boyer and Stanley Cohen in 1973. It was the result of a series of advancements in techniques that allowed the direct modification of the genome. Important advances included the discovery of restriction enzymes and DNA ligases, the ability to design plasmids and technologies like polymerase chain reaction and sequencing. Transformation of the DNA into a host organism was accomplished with the invention of biolistics, Agrobacterium-mediated recombination and microinjection. The first genetically modified animal was a mouse created in 1974 by Rudolf Jaenisch. In 1976, the technology was commercialised, with the advent of genetically modified bacteria that produced somatostatin, followed by insulin in 1978. In 1983, an antibiotic resistant gene was inserted into tobacco, leading to the first genetically engineered plant. Advances followed that allowed scientists to manipulate and add genes to a variety of different organisms and induce a range of different effects. Plants were first commercialized with virus resistant tobacco released in China in 1992. The first genetically modified food was the Flavr Savr tomato marketed in 1994. By 2010, 29 countries had planted commercialized biotech crops. In 2000 a paper published in Science introduced golden rice, the first food developed with increased nutrient value.
Fisheries law is an emerging and specialized area of law. Fisheries law is the study and analysis of different fisheries management approaches such as catch shares e.g. individual transferable quotas; TURFs; and others. The study of fisheries law is important in order to craft policy guidelines that maximize sustainability and legal enforcement. This specific legal area is rarely taught at law schools around the world, which leaves a vacuum of advocacy and research. Fisheries law also takes into account international treaties and industry norms in order to analyze fisheries management regulations. In addition, fisheries law includes access to justice for small-scale fisheries and coastal and aboriginal communities and labor issues such as child labor laws, employment law, and family law.
A genetically modified potato is a potato that has had its genes modified, using genetic engineering. Goals of modification include introducing pest resistance, tweaking the amounts of certain chemicals produced by the plant, and to prevent browning or bruising of the tubers. Varieties modified to produce large amounts of starches may be approved for industrial use only, however, not for food.
Alison L. Van Eenennaam is a Cooperative Extension Specialist in the Department of Animal Science at the University of California, Davis and runs the Animal Genomics and Biotechnology Laboratory. She has served on national committees such as the USDA National Advisory Committee on Biotechnology in the 21st Century (AC21) and was awarded the 2014 Borlaug CAST Communication Award. Van Eenennaam writes the Biobeef Blog.
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