Transgenic Technology in Marine Organisms 13.5 Concerns and Future Perspectives 405
Part B | 13.5
transgenes was detected in genomic DNA isolated from
a Porphyra thallus after multiple passages (Fig 13.16).
These results confirm the development of a protocol for
transferring foreign genes into Porphyra.
13.5 Concerns and Future Perspectives
Application of transgenic technology to produce genetically modified (GM) food fish and ornamental fish
with beneficial traits such as enhanced somatic growth
and resistance to diseases, or diverse body color is on
the rise. There have been ground-breaking discoveries
made in the past few years based on transgenic fish
models, and such applications are expected to continue
to thrive in the future. Techniques to produce transgenic fish have improved tremendously in the last two
decades; nonetheless, there are still concerns about low
efficiency, mosaic expression, non-fish components of
the transgenes, and the long generation time for certain
fish species. The following advances would thus be essential in developing the next generation of transgenic
fish:
i) The development of more efficient mass gene transfer technologies
ii) The development of targeted gene transfer technology such as the embryonic stem cell gene transfer
method
iii) Identification of more suitable fish-origin promoters to direct the expression of transgenes at optimal
levels and desired time
iv) The development of methods to shorten the time required to generate homozygous offspring.
Despite the promising future of the application
of transgenic technology, there are great concerns
about the environmental impacts of GM food fish
or pets. Based on mathematical modeling, Howard
et al. [13.150] proposed a Trojan gene effect hypothesis
using male transgenic medaka expressing the salmon
growth hormone gene. They proposed that the release
of such fish into the environment could ultimately lead
to the extinction of the wild population, owing to their
advantage in mating with the wild females. The study
provides a sound analysis of the potential impact of
the accidental release of transgenic fish into the environment, reminding us of the delicate interaction
between a newly introduced species and the native population and environment. However, we would reason
that the potential environmental impact by transgenic
fish is controllable and even avoidable. First of all,
the Trojan gene effect might not necessarily exist for
other types of transgenes or in other fish species. In
practice, transgenic fish should be maintained in confined areas to avoid their escape into nearby waters.
Moreover, as the desirable genetic traits can be introduced into fish, the undesirable behavior traits could
be possibly removed from the transgenic population by
screening the behavior pattern of each transgenic individual. Ultimately, the establishment of a sterile transgenic population can be applied to avoid the spreading
of transgenes into the wild population. Ideally, such
sterility should be reversible, otherwise it would mean
the loss of the goose that lays the golden egg. Finally, from a historical perspective, the concerns in
the early days that arose from the environmental impacts of recombinant DNA technology have not been
realized and many lessons can be learned from this
experience.
The acceptance of GM fish and other transgenic
marine organisms as food by society is a key factor
for the development of transgenic marine organisms
as a new source of affordable and high-quality food.
Largely, the concern is due to the public perception that
GM food is unsafe to human health. Safety is the ultimate goal of GM food development and it relies on
a thorough characterization of the transgenes used and
the safety assessment of the transgenic products, resembling the development of new drugs. Unfortunately, it
is a fact that there is always a subpopulation of people who are allergic, to different degrees, to many of
the existing natural food sources, such as peanuts and
shellfish. Therefore, the challenge to develop GM food
with absolutely no adverse effect on every single individual in the human population is great. A thorough
evaluation process to fully analyze any health risk of
GM food to humans should be established, and the
information should be clearly delivered to the public
and well marked on the food products. The development of gene-inactivated transgenic marine organisms
may be more acceptable by people who are concerned
about the safety of the new genes that are introduced
into the marine organisms. Take GM fish, for instance,
one candidate GM fish is transgenic fish strains with
their myostatin gene being inactivated. Inactivation of
Part B | 13.5
transgenes was detected in genomic DNA isolated from
a Porphyra thallus after multiple passages (Fig 13.16).
These results confirm the development of a protocol for
transferring foreign genes into Porphyra.
13.5 Concerns and Future Perspectives
Application of transgenic technology to produce genetically modified (GM) food fish and ornamental fish
with beneficial traits such as enhanced somatic growth
and resistance to diseases, or diverse body color is on
the rise. There have been ground-breaking discoveries
made in the past few years based on transgenic fish
models, and such applications are expected to continue
to thrive in the future. Techniques to produce transgenic fish have improved tremendously in the last two
decades; nonetheless, there are still concerns about low
efficiency, mosaic expression, non-fish components of
the transgenes, and the long generation time for certain
fish species. The following advances would thus be essential in developing the next generation of transgenic
fish:
i) The development of more efficient mass gene transfer technologies
ii) The development of targeted gene transfer technology such as the embryonic stem cell gene transfer
method
iii) Identification of more suitable fish-origin promoters to direct the expression of transgenes at optimal
levels and desired time
iv) The development of methods to shorten the time required to generate homozygous offspring.
Despite the promising future of the application
of transgenic technology, there are great concerns
about the environmental impacts of GM food fish
or pets. Based on mathematical modeling, Howard
et al. [13.150] proposed a Trojan gene effect hypothesis
using male transgenic medaka expressing the salmon
growth hormone gene. They proposed that the release
of such fish into the environment could ultimately lead
to the extinction of the wild population, owing to their
advantage in mating with the wild females. The study
provides a sound analysis of the potential impact of
the accidental release of transgenic fish into the environment, reminding us of the delicate interaction
between a newly introduced species and the native population and environment. However, we would reason
that the potential environmental impact by transgenic
fish is controllable and even avoidable. First of all,
the Trojan gene effect might not necessarily exist for
other types of transgenes or in other fish species. In
practice, transgenic fish should be maintained in confined areas to avoid their escape into nearby waters.
Moreover, as the desirable genetic traits can be introduced into fish, the undesirable behavior traits could
be possibly removed from the transgenic population by
screening the behavior pattern of each transgenic individual. Ultimately, the establishment of a sterile transgenic population can be applied to avoid the spreading
of transgenes into the wild population. Ideally, such
sterility should be reversible, otherwise it would mean
the loss of the goose that lays the golden egg. Finally, from a historical perspective, the concerns in
the early days that arose from the environmental impacts of recombinant DNA technology have not been
realized and many lessons can be learned from this
experience.
The acceptance of GM fish and other transgenic
marine organisms as food by society is a key factor
for the development of transgenic marine organisms
as a new source of affordable and high-quality food.
Largely, the concern is due to the public perception that
GM food is unsafe to human health. Safety is the ultimate goal of GM food development and it relies on
a thorough characterization of the transgenes used and
the safety assessment of the transgenic products, resembling the development of new drugs. Unfortunately, it
is a fact that there is always a subpopulation of people who are allergic, to different degrees, to many of
the existing natural food sources, such as peanuts and
shellfish. Therefore, the challenge to develop GM food
with absolutely no adverse effect on every single individual in the human population is great. A thorough
evaluation process to fully analyze any health risk of
GM food to humans should be established, and the
information should be clearly delivered to the public
and well marked on the food products. The development of gene-inactivated transgenic marine organisms
may be more acceptable by people who are concerned
about the safety of the new genes that are introduced
into the marine organisms. Take GM fish, for instance,
one candidate GM fish is transgenic fish strains with
their myostatin gene being inactivated. Inactivation of