Genetically Modified Organism
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berkuasa dan berilmu walhal semuanya atas kehendak dan ketentuan Allah
jua!!! Manusia suka tukar apa yang
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A genetically modified organism (GMO) is an
organism
whose genetic
material has been altered using genetic engineering techniques. Organisms that
have been genetically modified include micro-organisms such as bacteria and
yeast, insects, plants, fish, and mammals. GMOs are the source of genetically modified foods, and are also
widely used in scientific research and to produce goods other than food. The
term GMO is very close to the technical legal term, 'living modified
organism' defined in the Cartagena Protocol on Biosafety,
which regulates international trade in living GMOs (specifically, "any
living organism that possesses a novel combination of genetic material obtained
through the use of modern biotechnology").
This article focuses on what organisms have been
genetically engineered, and for what purposes. The article on genetic engineering focuses on the history and
methods of genetic engineering, and on applications of genetic engineering and
of GMOs. Both articles cover much of the same ground but with different
organizations (sorted by organism in this article; sorted by application in the
other). There are separate articles on genetically modified crops, genetically modified food, regulation of
the release of genetic modified organisms, and controversies.
Genetic modification involves the
insertion or deletion of genes. When genes are inserted, they usually come from
a different species, which is a form of horizontal gene transfer. In nature this
can occur when exogenous DNA penetrates the cell
membrane for any reason. To do this artificially may require attaching the
genes to a virus
or just physically inserting the extra DNA into the nucleus of the intended
host with a very small syringe, or with very small particles fired from a gene gun.[1][2][3]
However, other methods exploit natural forms of gene transfer, such as the
ability of Agrobacterium to transfer genetic material to
plants,[4]
or the ability of lentiviruses to transfer genes to animal cells.[5
The general principle of producing a
GMO is to add new genetic material into an organism's genome. This is
called genetic engineering and was made possible
through the discovery of DNA
and the creation of the first recombinant
DNA molecules by Paul Berg in 1972.
GMOs are used in biological and medical research,
production of pharmaceutical drugs, experimental medicine
(e.g. gene
therapy), and agriculture (e.g. golden rice,
resistance to herbicides). The term "genetically modified
organism" does not always imply, but can include, targeted insertions of
genes from one species
into another. For example, a gene from a jellyfish, encoding a fluorescent
protein called GFP, can be physically linked and thus co-expressed
with mammalian genes to identify the location of the protein encoded by the
GFP-tagged gene in the mammalian cell. Such methods are useful tools for biologists in
many areas of research, including those who study the mechanisms of human and
other diseases or fundamental biological processes in eukaryotic or
prokaryotic
cells.
Plants
Transgenic plants
Transgenic plants have been engineered for scientific
research, to create new colours in plants, and to create different crops.
In research, plants are engineered to help discover the
functions of certain genes. One way to do this is to knock out
the gene of interest and see what phenotype
develops. Another strategy is to attach the gene to a strong promoter and see what happens when it is over
expressed. A common technique used to find out where the gene is expressed is
to attach it to GUS or a similar reporter
gene that allows visualisation of the location.[7]'
After thirteen years of collaborative research by an Australian
company – Florigene,
and a Japanese company – Suntory, created a blue rose
(actually lavender or mauve) in 2004.[8]
The genetic engineering involved three alterations – adding two genes, and
interfering with another. One of the added genes was for the blue plant pigment delphinidin
cloned from the pansy.[9]
The researchers then used RNA
interference (RNAi) technology to depress all color production by
endogenous genes by blocking a crucial protein in color production, called dihydroflavonol 4-reductase) (DFR),
and adding a variant of that protein that would not be blocked by the RNAi but
that would allow the delphinidin to work.[9]
The roses are sold worldwide.[10][11]
Florigene has also created and sells lavender-colored carnations that are genetically engineered in
a similar way.[9]
Simple plants and plant cells have been genetically
engineered for production of biopharmaceuticals in bioreactors
as opposed to cultivating plants in open fields. Work has been done with duckweed Lemna minor[12]
and the moss Physcomitrella patens.[13][14]
An Israeli company, Protalix, has developed a method to produced therapeutics
in cultured transgenic carrot and tobacco cells.[15]
Protalix and its partner, Pfizer, received FDA approval to market its drug, a
treatment for Gaucher's Disease, in 2012.[16]
GM crops
Main article: Genetically modified crops
In agriculture, genetically engineered crops are
created to possess several desirable traits,
such as resistance to pests, herbicides, or harsh environmental conditions, improved
product shelf
life, increased nutritional value, or production of valuable goods such as
drugs (pharming). Since the first commercial
cultivation of genetically modified plants in 1996, they have been modified to
be tolerant to the herbicides glufosinate and glyphosate,
to be resistant to virus damage as in Ringspot virus-resistant GM papaya, grown in
Hawaii, and to produce the Bt toxin, an insecticide that is documented
as non-toxic to mammals.[17]
Plants, including algae, jatropha, maize, and other
plants have been genetically modified for use in producing fuel, known as biofuel.
Critics have objected to GM crops per se on several
grounds, including ecological concerns, and economic concerns raised by the
fact these organisms are subject to intellectual property law. GM crops also
are involved in controversies over GM food with respect to whether food
produced from GM crops is safe and whether GM crops are needed to address the
world's food needs. See the genetically modified food
controversies article for discussion of issues about GM crops and GM food.
Cisgenic plants
Cisgenesis, sometimes also called intragenesis,
is a product designation for a category of genetically engineered plants. A
variety of classification schemes have been proposed[18]
that order genetically modified organisms based on the nature of introduced
genotypical changes rather than the process of genetic engineering.
While some genetically modified plants are developed by
the introduction of a gene originating from distant, sexually incompatible
species into the host genome, cisgenic plants contain genes that have been
isolated either directly from the host species or from sexually compatible species.
The new genes are introduced using recombinant DNA methods and gene transfer.
Some scientists hope that the approval process of cisgenic plants might be
simpler than that of proper transgenics,[19]
but it remains to be seen.[20]
Microbes
Bacteria were the first organisms to be modified in the
laboratory, due to their simple genetics.[21]
These organisms are now used for several purposes, and are particularly
important in producing large amounts of pure human proteins for use
in medicine.[22]
Genetically modified bacteria are
used to produce the protein insulin to treat diabetes.[23]
Similar bacteria have been used to produce clotting
factors to treat haemophilia,[24]
and human growth hormone to treat various forms of
dwarfism.[25][26]
In addition, various genetically engineered
micro-organisms are routinely used as sources of enzymes for the
manufacture of a variety of processed foods. These include alpha-amylase
from bacteria, which converts starch to simple sugars, chymosin from
bacteria or fungi that clots milk protein for cheese making, and pectinesterase
from fungi which improves fruit juice clarity.[27]
Mammals
Some chimeras, like the blotched mouse shown, are created
through genetic modification techniques like gene
targeting.
Genetically modified mammals are an
important category of genetically modified organisms.[28]
Ralph L. Brinster and Richard Palmiter developed
the techniques responsible for transgenic mice, rats, rabbits, sheep, and pigs
in the early 1980s, and established many of the first transgenic models of
human disease, including the first carcinoma caused by a transgene. The process
of genetically engineering animals is a slow, tedious, and expensive process.
However, new technologies are making genetic modifications easier and more
precise.[29]
The first transgenic (genetically modified) animal was
produced by injecting DNA into mouse embryos then implanting the embryos in
female mice.[30]
Genetically modified animals currently being developed
can be placed into six different broad classes based on the intended purpose of
the genetic modification:
- to research human diseases (for example, to develop animal
models for these diseases);
- to produce industrial or consumer products (fibres
for multiple uses;
- to produce products intended for human therapeutic
use (pharmacutical products or tissue for implantation);
- to enrich or enhance the animals' interactions with
humans (hypo-allergenic pets);
- to enhance production or food quality traits (faster
growing fish, pigs that digest food more efficiently);
- to improve animal health (disease resistance)[31]
Research use
Transgenic animals are used as experimental models to
perform phenotypic
and for testing in biomedical research.[32]
Genetically modified (genetically engineered) animals are
becoming more vital to the discovery and development of cures and treatments
for many serious diseases. By altering the DNA or transferring DNA to an
animal, we can develop certain proteins that may be used in medical treatment.
Stable expressions of human proteins have been developed in many animals,
including sheep, pigs, and rats. Human-alpha-1-antitrypsin,[33]
which has been tested in sheep and is used in treating humans with this
deficiency and transgenic pigs with human-histo-compatibility have been studied
in the hopes that the organs will be suitable for transplant with less chances
of rejection.
Scientists have genetically engineered several organisms,
including some mammals, to include green fluorescent protein (GFP) for
medical research purposes (Chalfie, Shimoura,
and Tsien
were awarded the Nobel prize in 2008 for GFP[34]).
For example fluorescent pigs have been bred in the US in 2000,[35]
in Korea in 2002,[36]
in Taiwan in 2006,[37]
in China in 2008[38]
and Japan in 2009.[39]
These pigs were bred to study human organ transplants,[38]
regenerating ocular photoreceptor cells,[40]
neuronal cells
in the brain,[40]
regenerative medicine via stem cells,[41]
tissue engineering,[39]
and other diseases. In 2011 a Japanese-American Team created green-fluorescent cats in order to find
therapies for HIV/AIDS
and other diseases[42]
as Feline immunodeficiency virus (FIV)
is related to HIV.[43]
In 2009, scientists in Japan announced that
they had successfully transferred a gene into a primate species (marmosets) and
produced a stable line of breeding transgenic primates for the first time.[44][45]
Their first research target for these marmosets was Parkinson's disease, but they were also
considering Amyotrophic lateral sclerosis and Huntington's disease.[46]
Producing human
therapeutics
Within the field known as pharming, intensive research has been conducted
to develop transgenic animals that produce biotherapeutics.[47]
On 6 February 2009, the U.S. Food and Drug Administration
approved the first human biological drug produced from such an animal, a goat. The drug, ATryn, is an anticoagulant
which reduces the probability of blood clots
during surgery
or childbirth.
It is extracted from the goat's milk.[48]
Production or
food quality traits
Enviropig is a genetically enhanced line of Yorkshire
pigs created with the capability of digesting plant phosphorus
more efficiently than conventional Yorkshire pigs and dubbed them Enviropig.[49]
These pigs produce the enzyme phytase, which breaks down the indigestible phosphorus, in
their saliva. The enzyme was introduced into the pig chromosome by pronuclear microinjection.
With this enzyme, Enviropig is able to digest cereal grain phosphorus,
so there is then no need to supplement the pigs' diet with either phosphate minerals or commercially produced
phytase, and less phosphorus is lost in the manure.[49]
Enviropig would reduce feed costs because farmers would not need to purchase
feed including the phytase, and it also would reduce the potential of water
pollution since the Enviropig excretes from 30 to 70.7% less phosphorus in
manure depending upon the age and diet.[49][50]
The lower concentrations of phosphorus in surface
runoff reduces algal
growth, because phosphorus is the limiting
nutrient for algae.[49]
Because algae consume large amounts of oxygen, it can result in dead zones for
fish. This would not only be advantageous for the waters surrounding the pigs,
but also for the water neighboring the areas which use the manure for
fertilizers. There are no current regulations or pending approvals on the
Enviropig for human consumption in the United States.[51]
In February 2010, Environment Canada determined that Enviropigs are in
compliance with the Canadian Environmental Protection Act and can be produced
outside of the research context in controlled facilities where they are
segregated from other animals.[52]
In 2011, Chinese scientists generated dairy cows
genetically engineered with genes for human beings to produce milk that would
be the same as human breast milk.[53]
This could potentially benefit mothers who cannot produce breast milk but want
their children to have breast milk rather than formula. Aside from milk
production, the researchers claim these transgenic
cows to be identical to regular cows.[54]
Two months later scientists from Argentina
presented Rosita, a transgenic cow incorporating two human genes, to produce
milk with similar properties as human breast milk.[55]
In 2012, researchers from New Zealand also developed a genetically engineered cow
that produced allergy-free milk.[56]
In 2006, a pig was engineered to produce omega-3 fatty acids through the expression of a roundworm
gene.[57]
Goats have been genetically engineered to produce milk
with strong spiderweb-like silk proteins in their milk.[58]
Genetically modified fish have been
developed with promoters driving an over-production of growth
hormone for use in the aquaculture industry to increase the speed of development
and potentially reduce fishing pressure on wild stocks. AquaBounty, a
biotechnology company working on bringing a GM salmon to market, claims that
their GM AquAdvantage salmon can mature in half the time it takes non-GM salmon
and achieves twice the size.[59]
AquaBounty has applied for regulatory approval to market their GM salmon in the
US. As of May 2012 the application was still pending.[60]
Human gene
therapy
Gene therapy,[61]
uses genetically modified viruses to deliver
genes that can cure disease into humans. Although gene therapy is still
relatively new, it has had some successes. It has been used to treat genetic
disorders such as severe combined immunodeficiency,[62]
and treatments are being developed for a range of other currently incurable
diseases, such as cystic fibrosis,[63]
sickle cell anemia,[64]
Parkinson's disease,[65][66]
cancer,[67][68]
diabetes[69]
and muscular dystrophy.[70]
Current gene therapy technology only targets the non-reproductive cells meaning
that any changes introduced by the treatment can not be transmitted to the next
generation. Gene therapy targeting the reproductive cells—so-called "Germ
line Gene Therapy"—is very controversial and is unlikely to be developed
in the near future.
Insects
Fruit flies
In biological research, transgenic fruit flies (Drosophila melanogaster) are model
organisms used to study the effects of genetic changes on development.[71]
Fruit flies are often preferred over other animals due to their short life
cycle, low maintenance requirements, and relatively simple genome compared to
many vertebrates.
Mosquitoes
In 2010, scientists created "malaria-resistant
mosquitoes" in the laboratory.[72][73][74]
The World Health Organisation estimated that Malaria killed almost one million
people in 2008.[75]
Genetically modified male mosquitoes containing a lethal gene have been
developed in order to combat the spread of Dengue
fever.[76]
Aedes
aegypti mosquitoes, the single most important carrier of dengue fever, were
reduced by 80% in a 2010 trial of these GM mosquitoes in the Cayman Islands.[77][78]
Between 50 and 100 million people are affected by Dengue fever every year and
40,000 people die from it.[79]
Bollworms
A strain of Pectinophora gossypiella (Pink
bollworm) has been developed that contains a fluorescent marker in their
DNA. This allows researchers to monitor bollworms that have been sterilized by
radiation and released in order to reduce bollworm infestation.[79][80]
Aquatic Life
Cnidarians
Cnidarians such as Hydra
and the sea anemone Nematostella vectensis have become attractive model
organisms to study the evolution of immunity and certain developmental processes. An
important technical breakthrough was the development of procedures for
generation of stably transgenic hydras and sea anemones by embryo microinjection.[81]
Fish
GM fish are used for scientific research and as pets, and
are being considered for use as food and as aquatic pollution sensors.
Genetically engineered fish are widely used in basic
research in genetics and development. Two species of fish, zebrafish and
medaka,
are most commonly modified because they have optically clear chorions (shells),
rapidly develop, and the 1-cell embryo is easy to see and microinject with
transgenic DNA.[82]
The GloFish is a patented[83]
brand of genetically modified (GM) fluorescent zebrafish
with bright red, green, and orange fluorescent color. Although not originally
developed for the ornamental fish trade, it became the first genetically
modified animal to become publicly available as a pet when it was introduced
for sale in 2003.[84]
They were quickly banned for sale in California.[85]
Genetically modified fish have been
developed with promoters driving an over-production of "all fish" growth
hormone for use in the aquaculture 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 salmon,[86]
trout[87]
and tilapia.[88]
AquaBounty, a biotechnology company working on bringing a GM salmon to market,
claims that their GM AquAdvantage salmon can mature in half the time it takes
non-GM salmon and achieves twice the size.[59]
AquaBounty has applied for regulatory approval to market their GM salmon in the
US. As of December 2012 the application was still pending.[89][60]
Several academic groups have been developing GM zebrafish
to detect aquatic pollution. The lab that originated the GloFish discussed
above originally developed them to change color in the presence of pollutants,
to be used as environmental sensors.[90][91]
A lab at University of Cincinnati has been developing GM zebrafish for the same
purpose,[92][93]
as has a lab at Tulane University.[94]
Regulation
Main article: Regulation of genetic engineering
The regulation of genetic engineering concerns the
approaches taken by governments to assess and manage the risks associated with
the use of genetic engineering technology and the
development and release of genetically modified organisms (GMO), including genetically modified crops and genetically modified fish. There are
differences in the regulation of GMOs between countries, with some of the most
marked differences occurring between the USA and Europe.[95]
Regulation varies in a given country depending on the intended use of the
products of the genetic engineering. For example, a crop not intended for food
use is generally not reviewed by authorities responsible for food safety.[96]
Controversy
Main article: Genetically modified food
controversies
There are controversies around GMOs on several levels,
including whether making them is ethical, whether food produced with them is
safe, whether such food should be labeled and if so how, whether agricultural
biotech is needed to address world hunger now or in the future, and more
specifically to GM crops—intellectual property and market dynamics;
environmental effects of GM crops; and GM crops' role in industrial
agricultural more generally.
See also
- Timeline of genetically
modified organisms
- Detection of
genetically modified organisms
- Reading Scientific Services
(detecting GMOs)
- BioSteel
- Chimera (genetics)
- Gene flow
- Gene pool
- Genetic
erosion
- Horizontal gene transfer
- Non-GMO Project
- Organic
farming
- SMART breeding
- Sperm-mediated gene transfer
- Synthetic biology
