AGRICULTURAL RESEARCH COMMUNICATION CENTRE
Agri. Review, 36 (1) 2015 : 46-53
www.arccjournals.com
Print ISSN:0253-1696 / Online ISSN:0976-0539
Transgenic animal technology: Recent advances and applications: A Review
Rakesh Kumar*, Alok Kumar Yadav, Vikas Kumar Singh 1, Rajesh Kumar Vandre 2, Pankaj Kumar Singh3,
Nishant Verma, Ramendra Das and M.R. Vineeth
Dairy Cattle Breeding Division,
ICAR-National Dairy Research Institute, Karnal-132 001, Haryana.
Received: 14-08-2014
Accepted: 26-01-2015
DOI: 10.5958/0976-0741.2015.00005.7
ABSTRACT
Transgenic animal technologies are one of the fastest growing techniques in the biotechnology areas. It is used to incorporate
exogenous genes into the animal genome by genetic engineering technology so that these genes can be inherited and expressed
by offspring. Two fundamental determinants of the success of any transgenic exploitation of a livestock species are the
transport of DNA across the plasma membrane of the recipient cell, and the transport of that DNA across the nuclear
membrane to gain access to the chromosomes. A variety of transgenic technologies are available like microinjection method,
chemical method mediated transgenesis, somatic cell nuclear transfer, restriction enzyme-mediated integration, retrovirusmediated gene transfer, sperm mediated gene transfer and embryonic stem cell mediated method etc. Use of transgenic
animals will provide solutions for drug research, xenotransplantation, disease resistance and tissue repair etc. This review
focuses on various methods of transgenesis and its application.
Key words: Applications, Methods, Transgenesis.
The term transgenic animal refers to an animal in
which there has been a deliberate modification of the genome,
in contrast to spontaneous mutation. It is used to integrate
exogenous genes into the animal genome by genetic
engineering technology so that these genes can be expressed
and inherited by offspring. Foreign DNA is introduced into
the animal, using recombinant DNA technology, which gets
transmitted through the germ line so that every cell, including
germ cells, of the animal contains the same modified genetic
material. If the germ cell line is altered, characters will be
passed on to succeeding generations in normal reproduction.
The transgenic efficiency and precise control of gene
expression are the key limiting factors in the production of
transgenic animals. Advance studies will allow transgenic
technology to explore gene function, animal genetic
improvement, bioreactors, animal disease models and organ
transplantation. Transgenesis may involve whole organisms,
rather than individual cells and there may be in vivo alteration
of body function. Recent developments in animal gene
transfer techniques are microinjection method, sperm
mediated gene transfer method, embryonic stem cell mediated
gene transfer, somatic cell nuclear transplantation method,
nuclear transfer and retroviral vector method. These
techniques can provide a better platform to develop transgenic
animals for breeding new animal varieties and promote the
development of medical sciences, livestock production and
other fields.
Transgenesis allows improvement of nutrients in
animal products, including their quantity, the quality of the
whole food, and specific nutritional composition. Transgenic
technology could provide a means of transferring or
increasing nutritionally beneficial traits. For example,
enhancing the omega-3 fatty acid in fish consumed by humans
may contribute to a decreased occurrence of coronary heart
disease. In fact, transgenic pigs that contain elevated levels
of omega-3 fatty acids have been produced (Lai et al., 2006).
Furthermore, transfer of a transgene that elevates the levels
of omega-3 fatty acids into pigs may enhance the nutritional
quality of pork (Lai et al., 2006). The production of lower
fat, more nutritious animal products produced by transgenesis
could enable improvements in public health. Another aspect
of manipulating carcass composition is that of altering the
fat or cholesterol composition of the carcass. By altering the
metabolism or uptake of cholesterol and/or fatty acids, the
content of fat and cholesterol of meats, eggs, and cheeses
could be lowered. There is also the possibility of introducing
beneficial fats such as the omega-3 fatty acids from fish or
other animals into our livestock (Lai et al., 2006). In addition,
*Corresponding author e-mail:[email protected], 1Division of Immunology, IVRI, Izatnagar, Bareilly (U.P), India.
2
College of Veterinary science and Animal husbandry, Rewa (MP), India, 3LPM Section, ICAR-NDRI, Karnal, Haryana.
Vol. 36 No. 1, 2015
receptors such as the low-density lipoprotein (LDL) receptor
gene and hormones like leptin are potential targets that would
decrease fat and cholesterol in animal products. Recent
progress has produced prion-free (Richt et al., 2007) and
suppressed prion livestock (Golding et al., 2006). Prions are
the causative agents in bovine spongiform encephalopathy
(BSE) or ‘mad cow disease’ in cattle and in Creutzfeldt-Jacob
disease (CJD) in humans. This is only a partial list of
organisms or genetic diseases that decrease production
efficiency and may also be targets for manipulation via
transgenic methodologies. Small improvements in milk
volume in Guzerat cows using genetic material from high
producing Holsteins could have a significant impact on
Brazilian beef production (Wheeler et al., 2010).
What is transgenic animal?: A transgenic animal is one
that carries a foreign gene that has been deliberately inserted
into its genome. It is the one which has been genetically altered
to have specific characteristics it otherwise would not have.
In animals, transgenesis either means transferring DNA into
the animal or altering DNA of the animal. Transgenic animal
are genetically modified to contain a gene from a different
species following gene transplantation or resulting from the
molecular manipulations of endogenous genomic DNA. The
new gene is inherited by offspring in the same way as the
organism’s own genes. The earliest transgenic approaches
involved transferring DNA, usually by injection into a
fertilized mouse egg. However, since it is not possible to
control the site of integration of the foreign DNA using this
technique, it is a relatively imprecise tool. Mice resulting from
this technique are generally called “overexpressors”.
Currently over 95% of transgenic animals used in
biomedical research are mice. Over 80% of mouse genes
function the same as those in humans. Mice also have a short
reproduction cycle and their embryos are amenable to
manipulation. Mice are therefore an ideal human surrogate
in the study of most diseases. It is hoped that the refinement
of transgenesis techniques in mice will ultimately allow for a
corresponding reduction in the use of “higher” animals, such
as dogs and non-human primates, in biomedical research.
Other transgenic animals include rats, pigs and sheep.
METHODS USED TO PRODUCE TRANSGENIC
ANIMALS
Microinjection: DNA microinjection has become the most
commonly applied method for gene transfer in animals. Using
DNA microinjection, mouse was the first animal to undergo
successful gene transfer. Microinjection of embryos with
DNA has been the traditional approach for generating
transgenic livestock.
47
For processes such as cellular or pronuclear injection the
target cell is positioned under the microscope and two
micromanipulators— one holding the pipette and other one,
holding a micro capillary needle usually between 0.5 to 5 µm
in diameter (larger if injecting stem cells into an embryo)
are used to penetrate the cell membrane and/or the nuclear
envelope (David and Matthew, 2013).
The method relies on random integration of the
transgenic DNA via the recruitment of cellular DNA repair
pathways and remains a highly inefficient process with
success rates of only 1-4% (Niemann and kues 2000). Apart
from all these drawbacks the method is still being used to
generate transgenic animals (Baldassarre et al., 2003) and is
being improved with co-injection of restriction enzymes with
the DNA to mediate incorporation of the transgene into the
chromosome (Thermes et al., 2002).
Retrovirus-mediated gene transfer: A retrovirus is a virus
that carries its genetic material in the form of RNA rather
than DNA. The retrovirus-mediated expression cloning
method is efficient because the number of the provirus
integrations in each cell is limited. This method was
successfully used in 1974 when a simian virus was inserted
into mice embryos, resulting in mice carrying this DNA. The
most important features of retrovirus as vectors are the
practically ease and effectiveness of gene transfer and target
cells specificity. When cells are infected by retroviruses, the
resultant viral DNA, after reverse transcription and
integration, becomes a part of the host cell genome to be
maintained for the life of the host cell (Ponder, 2002).
Retroviruses are being explored widely for apply in human
gene therapy and have been used in a precise condition to
treat genetic diseases (Thermes et al., 2002). Recently
lentivirus constructs have been made and used to infect
embryonic tissue resulting in the generation of transgenic rats
and mice (Rubinson et al., 2003). On the other hand, retroviral
methods of modifying the chicken genome are progressing
(Ivarie, 2003).
Somatic cell nuclear transfer: In genetics and
developmental biology, somatic cell nuclear transfer (SCNT)
is a laboratory technique for creating a viable embryo from a
body cell and an egg cell. The technique consists of taking
an enucleated oocyte (egg cell) and implanting a donor
nucleus from a somatic (body) cell. It is used in both
therapeutic and reproductive cloning. Dolly the Sheep,
famous for being the first successfully cloned mammal was
created using this process (Li et al., 2009). Somatic cell
nuclear transplantation has become a focus of study in stem
cell research. The aim of carrying out this procedure is to
48
AGRICULTURAL REVIEWS
obtain pluripotent cells from a cloned embryo. These cells
genetically matched the donor organism from which they
came. This gives them the ability to create patient specific
pluripotent cells, which could then be used in therapies or
disease research.(Lomax and Dewitt, 2013). A potential use
of stem cells genetically matched to a patient would be to
create cell lines that have genes linked to a patient’s particular
disease. By doing so, an in vitro model could be created,
would be useful for studying that particular disease,
potentially discovering its pathophysiology, and discovering
therapies (Lo and Parham, 2009). For example, if a person
with Parkinson’s disease donated his or her somatic cells,
the stem cells resulting from SCNT would have genes that
contribute to Parkinson’s disease. The disease specific stem
cell lines could then be studied in order to better understand
the condition. Another application of SCNT stem cell research
is using the patient specific stem cell lines to generate tissues
or even organs for transplant into the specific patient (Pera
and Trounson, 2013). A number of animals with genetically
identical appearance can be produced by somatic cell nuclear
transfer (SCNT). From current advancement of SCNT and
molecular techniques, production of a transgenic animal
becomes easier. Although cloning efficiency in goat is low,
the ability to propagate genetically identical animals, with a
gene or genes of interest, would be important for increasing
productivity and ultimately the economic livelihood. In this
paper, the potential applications and uses of SCNT technology
like production of transgenic goat for production of quality
milk and meat are discussed (Abdullah et al., 2011).
Sperm-mediated gene transfer: In the year 1971, the first
evidence of mammalian spermatozoa being able to take up
and transfer exogenous DNA was demonstrated by Bracket
et al. (1971). Sperm cells are exposed to foreign DNA, which
binds to the surface of sperm through specific protein-protein
interactions. There is currently a general agreement that only
two steps in the processes are well-established and fully
reproducible: (i) the spontaneous interaction between sperm
cells and foreign DNA molecules, and (ii) delivery of spermbound DNA to oocyte at fertilization. At present research
has been carried out to determine the appropriate conditions
to use when incubating DNA with sperm (Lavitrano et al.,
2006). This method is now being hopefully perceived as a
valuable technique for transgenic animal production.
To increases the effectiveness of sperm uptake of DNA
by various approaches are being taken. One is to attach the
recombinant DNA to the sperm head via an antibody
amalgamated to the DNA (Chang et al., 2002). The antibody
used in this work recognises surface proteins common to
sperm from cattle, pigs, sheep, chicken, goats, mice and
humans. An additional approach likewise lipofection
technique (Lai et al., 2006) or electroporation (Reith et al.,
2000) method has been used to produce transgenic progeny
by placing the DNA inside the sperm head. With the
improvement in techniques for culturing and expanding
spermatogonial stem cells there is now also the possibility of
engineering these cells in-vitro to generate transgenic sperm
that could be used to fertilise oocytes and generate transgenic
animals (Nagano et al., 2000).
Liposome’s mediated technology: Liposome is small bodies
consisting of membrane-like lipid layers surrounding hydrous
compartments. Cationic liposome was used to increase the
transfection efficiency of sperm cells. Association of the
cationic liposome/DNA complexes with sperm cells may
allow DNA to be carried into oocytes at fertilization (Bachiller
et al., 1991). However, sperm motility and fertilizing
capability of spermatozoa was lower at the higher
concentration of liposome as assessed by microscopic
observation. Recent report that BSA, a major serum protein,
could prevent the cellular uptake of liposome/DNA complexes
in cells. The high transgenic rates were reported more recently
in mouse F1 (41%) and F2 (37%) offspring via testis mediated
gene transfer (TMGT) using liposome treated plasmid DNA
(He et al., 2009). Furthermore, the existence of several
different types of liposome makes it difficult to make general
predictions as to the likelihood of success, in the absence of
specific empirical studies.
Linker (receptor) based method: The process of linking
the exogenous DNA to the head of the sperm was reported
by using the monoclonal antibody mAbC (Chang et al., 2002).
The antibody (mAbC) is a positively charged basic linker
protein; it binds to negatively charged DNA via ionic
interactions. These interactions specifically bind exogenous
DNA to sperm in a precise way. DNA can bind to polycations
in a strong but noncovalent manner forming soluble
complexes. DNA coupled with antibodies or antibodyfragments offers the ability to internalize the complexes via
receptor-mediated endocytosis (Varga et al., 2000).
Restriction enzyme-mediated integration (REMI):
Restriction enzyme-mediated integration (REMI), involves
the transformation of cells with a mixture of plasmid DNA,
linearized with a restriction enzyme, along with a restriction
enzyme that is capable of generating compatible cohesive
ends in the genome. REMI has proven useful for genetic
screens and for placing genetic and molecular markers at
particular points in the genome. Plasmids were linearized with
a restriction enzyme to generate single-stranded cohesive ends
and then introduced in vitro into decondensed sperm nuclei
using REMI. Shemesh et al. (2000) produced transgenic
Vol. 36 No. 1, 2015
49
TABLE 1: Lists of some recombinant proteins obtained from transgenic animals.
Protein
Source
Against
Antithrombin III
Tissue plasminogen activator
á-antitrypsin
Factor VIII, IX
á –Glucosidase
Fibrinogen
Glutarmic acid decarboxylase
Human serum albumin
Human protein c
Monoclonal antibodies
Pro 542
Lactoferrin
Goat
Sheep, pig
Sheep
Sheep, pig, cow
Rabbit
Cow, sheep
Goat
Cow, sheep
Goat
Chicken, cow, goat
Goat
Cow
Thrombosis
Thrombosis
Emphysema
Hemophilia
Pompe’s disease
Wound healing
Type 1 diabetes
Maintenance of blood volume
Thrombosis
Vaccine production
HIV
GI tract infection and infectious arthritis.
bovine sperms by combining REMI with liposome, and
demonstrated that these transgenic sperms could be used to
produce transgenic embryos and live offspring by IVF or AI.
Applications of transgenic animals
Human health: The main potential application of transgenic
animal is the production of recombinant and biologically
active proteins in the mammary gland and this in turn could
be used for the benefit of mankind. This is called as “Gene
Pharming”. Mammary gland is the preferred site for
production of these proteins because large quantities can be
extracted and purified (Meade et al., 1999 and Rudolph,
1999). Moreover, milk is a secreted body fluid that is normally
produced in large quantities and which could be collected
without causing any harm to the animals
Recombinant therapeutic proteins: Several novel
therapeutic proteins have been derived from the mammary
gland of transgenic animals. Many conventional methods
were used for the production of therapeutic proteins through
bacteria, plants, yeast etc, but most of them lack the machinery
for post translational modifications of eukaryotic genes. The
transgenic livestock serve as potential bioreactors for the
production of valuable proteins. Proteins like antithrombin
III (AT III), tissue plasminogen activator (TPA) and áantitrypsin have been derived from the mammary gland of
transgenic sheeps and goats. The human AT III (for the
treatment of heparin resistant patients) is expected to be in
market (Kues and Niemann, 2004). Glycosidase has been
produced in the milk of transgenic rabbits, which is used in
the treatment of Pompes diseases (Vanden Hout et al., 2001).
A topical antibiotic against Streptococcus mutans, which is
useful in the treatment of dental caries, is expected to complete
clinical trials.
Blood substitutes: Transgenic swine has been developed that
produce functional hemoglobin which has the same oxygen
binding capacity as that of normal human hemoglobin and
that could be purified from porcine blood (D’Agnillo, and
Chang 1988).
Antibodies and transgenic animals: ifferent varieties of
monoclonal and recombinant antibodies were produced in
transgenic goats and cattle (Meade et al., 1999; GrosseHovest et al., 2004). These antibodies are useful in targeting
cancerous cell. Kuroiwa et al. (2002) reported that Transchromosomal animals could be used for the production of
human therapeutic polyclonal antibodies.
Human disease models: Farm animals like cattle and pigs
could be used as an appropriate model for the study of human
diseases like cystic fibrosis, cancer and neuro-degenerative
diseases and their therapies (Theuring et al., 1995; Palmarini
and Fan, 2001 and Li and Engelhardt, 2003) Pigs could be
used as an effective model for the study of growth hormone
releasing hormone (GHRH) defects (Draghia – Akli et al.,
1999).
Carcass composition and growth enhancement:
Transgenic animals with exogenous gene constructs have
been produced which has enhanced growth rate and
improved quality of food. Growth hormone and insulin
like growth factors genes have been expressed at different
levels in transgenic animals. Transgenic cattle and salmon
fish have been produced that contains foreign gene
constructs. The introduction of chicken ski gene has caused
muscular hypertrophy in case of pigs and cattle (Bowen et
al., 1994). The acid meat gene or Rendement Napole gene
has been involved in low processing yields of pork there
by affecting the quality of meat in pig. Silencing the
expression of this gene in case of pigs alter the post mortem
pH and improve the quality of meat. Other genes like GH
releasing factor, IGF binding proteins also play a major
role in the modification of growth. Transgenic pig with
human metallothionein promoter had a significant
improvement in growth rate and feed conversion (Nottle
et al., 2001).
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AGRICULTURAL REVIEWS
Milk production and lactation: The advances in transgenic
technology provide ample chances to improve both the quality
and quantity of milk produced. The animals could be made
to secrete nutraceuticals in milk that may have an impact over
the growth of offspring. Casein variants are the main target
for improving the milk composition, which in turn alters the
physio-chemical properties of milk. Brophy et al. (2003)
reported that cloned transgenic cattle have been developed
that produce increased amounts of beta and kappa casein in
milk that increase the value of milk in the production of milk
based products like cheese, yoghurt and also increase the
shelf life of milk products. Transgenic animals also could be
developed to produce “infant milk” that has increased levels
of human lactoferrin, to generate lactose free milk for lactose
in tolerance populations by inhibiting the expression of
lactalbumin locus and to produce hypoallergenic milk by
knocking down the expression of B-lactoglobulin gene.
Transgenic animals could also be made to secrete antibodies
in their milk that give resistance against several diseases like
mastitis or to secrete antimicrobial peptides like lysozyme.
Grosvenor et al. (1993) reported that the milk composition
could also be altered by making the transgenic animals to
secrete growth factors in milk, which in turn affect the growth
and maturation of newborn offspring.
Disease resistance: The most important application of
transgenic technology is the manipulation of MHC (Major
Histocompatability Complex) genes, which influence the
immune response and increase the disease resistance capacity
of livestock. Clements et al. (1994) reported that transgenic
sheep have been developed that is resistant to Visna virus
infection. The transmission of bovine spongiform
encephalopathy (Scrapie) is also prevented by the knock down
of prion protein (Weissmann et al., 2002). Transgenic mice
have been developed that secretes recombinant antibodies in
milk to neutralize the corona virus responsible for
transmissible gastro enteritis (TGEV), an economically
important disease in case of pigs (Castilla et al., 1998).
Transgenic dairy cows that secrete lysostaphin into their milk
have higher resistance to mastitis due to the protection
provided by lysostaphin, which kills the
bacteria Staphylococcus aureus, in a dose-dependent manner
(Donovan et al., 2005), that protects the mammary gland
against this major mastitis-causing pathogen.
Transgenics in the aquaculture industries: Aquaculture
species have been particularly amenable to the production of
transgenics. Fish and shellfish tend to be highly fecund,
producing a large quantity of gametes. Many species can be
harvested for eggs and sperm and fertilisation in-vitro is often
straightforward. Eggs are relatively large and fertilised eggs
tend to develop outside the body, so no further manipulation,
such as re-implantation is necessary. The first successful gene
transfer experiment in fish occurred in 1985 in China. A
DNA construct consisting of human growth hormone under
control of the mouse metallothionein promoter was injected
into the germinal disc of an early-stage goldfish Carassius
auratus embryo. Microinjection procedures were quickly
perfected by other groups in Norway. Brem et al. (1988)
were among the first to produce a commercially important
fish (Nile tilapia, Oreochromis niloticus) bearing a human
growth hormone transgene, again under the control of the
mouse metallothionein promoter.
Recently, in Drosophila, zebra fish, and rats, direct
embryo injection of engineered zinc-finger nuclease (ZFN)
encoding mRNA or DNA has been used to generate heritable
knockout mutations at specific loci (Carroll 2008; Geurts et
al., 2009). Tsai et al. (2000) engineered a line of Japanese
abalone Haliotis divorsicolor suportexta which expresses
Chinook salmon growth hormone.
Production of pharmaceuticals in transgenic animals: The
production of therapeutic proteins from transgenic animals
usually involves their expression from mammary-gland
specific promoters to drive secretion of the transgene into
milk (Martin et al., 2005). In January 2004, GTC
Biotherapeutics submitted a Market Authorization
Application to the European Medicines Agency for ATryn®,
a recombinant form of human antithrombin produced in the
milk of transgenic goats (www.gtc-bio.com/pressreleases/
pr012604.html). This was the first product derived from a
transgenic animal to be submitted for formal regulatory
approval in Europe or the USA. Milk is presently the most
mature system to produce recombinant proteins from
transgenic organisms. Blood, egg white, seminal plasma and
urine are other theoretically possible systems, but all have
drawbacks. Blood, for instance, as of 2012 cannot store high
levels of stable recombinant proteins and biologically active
proteins in blood may alter the health of the animals
(Houdebine and Louis-Marie, 2009).
Xenotransplantation: The extraordinary success of humanto-human (an example of intraspecies or allotransplantation)
transplantation of vascularized organs (i.e. heart, kidney, liver,
lung and pancreas) has saved many lives over the past 25
years, but it has also created a significant need for donor
organs. It was recognized early on that for physiological,
anatomical, ethical and supply reasons the pig was the best
choice as a donor animal for vascularized organs. However,
serious immunological issues had to be over come before the
pig-to-human transplantation model could become a reality
(Platt et al., 1991).
Vol. 36 No. 1, 2015
The first published transgenic pig-to-primate xenograft used
a novel transgenic delivery system for human complement
regulatory proteins (McCurry et al., 1997). Transplant organs
may soon come from transgenic animals. Currently,
xenotransplantation is hampered by a pig protein that can
cause donor rejection but research is underway to remove
the pig protein and replace it with a human protein.
Tissue repair: Using induced pluripotent stem (iPS) cells
were directly injected into the vitreous of the
damaged retina of mice, the stem cells engrafted into the
retina, grow and repaired the vascular vessels (Mullin et al.,
2014).
Ethical issues related to transgenic animals: The social
opinion on transgenic animal research is divided almost in
the middle. Opinion surveys in USA, Japan and New Zealand
reveal that only 42, 54 and 58 percent, respectively, of the
people participating in the survey favour such research. The
main reasons for opposition of people are as follows.
1. Use of animals in biotechnological research causes great
suffering to the animals. But most people seem to accept some
animal suffering to serve the basic interest and welfare of
mankind; this attitude has been termed as interest-sensitive
speciesism.
2. It is felt that by using animals for the production of
pharmaceutical proteins we reduce them to mere factories.
This seems not to recognize that animals also are living beings
which feel pleasure and pain just as we do.
3. Some people feel that animals should be regarded as equal
to humans in that they have the same basic rights as human
beings. However, in most societies animals are relegated to a
position several steps below that of man.
4. An argument attempts to focus on integrity of species in
that each biological species has a right to exist as a separate
identifiable entity. But biologists do not regard a species as a
fixed, water-tight entity; rather they are regarded as dynamic,
constantly evolving groups.
5. Finally, the introduction of human genes into animals and
vice-versa, may be seen by many as clouding the definition
of “humanness”. But most of the known human genes are not
unique and comparable genes do occur in animals. In addition,
many retroviruses have integrated into the human genome
without any recognizable devaluation of our humanness.
Limitations of transgenices: The transgenic technology even
though has tremendous applications in livestock improvement
programmes; still it has lots of limitations:
51
* Insertional mutations resulting in alteration of important
biological processes.
* Unregulated gene expression resulting in improper
expression of gene products.
* Possibility of side effects in transgenic animals like arthritis,
dermatitis and cancer etc.
CONCLUSION
In the mid-1980s, the advent of transgenic
technologies generated great excitement in the scientific
community and the pharmaceutical industry. The acknowledged
consequences and potential were equal to the societal
implications and translation of the outlined basic research
technologies toward fruitful applications. At the time,
transgenesis were considered the next wave in the maturation
of the developing field of biotechnology. Twenty-five years
later, we now find ourselves positioned to reap the benefits of
advances that are still deemed to be, if not in their infancy, in
their adolescence. Although there are various products poised
for launch, market, ethical and product concerns have matured
considerably as we have advanced into the 21st century. The
challenges are daunting, the implications thought provoking,
with results still appearing to loom just around the corner. As
in the case of related technologies, including stem cell-based
genetic therapies, it will be interesting to observe the acceptance
of newly engineered products that hold the promise of having
a tremendous impact on societal needs and human health.
The emergence of transgenic technology has
widened the scope of development in case of farm animals
and the advent of new molecular biology techniques has paved
way by giving a new dimension to animal breeding. The
transgenic technology is one of an important tool to meet the
future challenges for increased animals production. The
biological products from animal source should be handled
with safety as they are subject to contamination and could be
damaged very easily. Thus, safety guidelines should be
developed for the commercial exploitation of recombinant
proteins and ensure that the transmission of pathogens from
animals to human beings is prevented.
Therefore, the genetically engineered animals and
biotechnology will play a vital role in the production of
pharmaceutical proteins and bring about a complete
refinement in agriculture production by increasing the quality
and quantity of production, protection of environment,
maintenance of genetic diversity and overall improvement
in animals welfare.
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