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Biotecnologia Aplicada
Elfos Scientiae
ISSN: 0684-4551
Vol. 13, Num. 1, 1996
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Biotecnologia Aplicada 1996 Volume 3 No. 1
TRANSGENIC FISH AND AQUACULTURE
Thomas T. Chen
Biotechnology Center and Department of Molecular & Cell Biology.
Universityof Connecticut, 184 Auditorium Road, U-149, Storrs, CT
06269-3149.
Code Number:BA96030
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Introdution of foreign DNA into developing embryos by
microinjection and electroporation is currently used as a
standard method to produce a wide range of transgenic animal
species, includingt fish. In addition to conducting basic
research, this technique offers exciting potential of improving
the genetic background of aquaculture important finfish and
shellfish species.Studies conducted in our laboratory and those
of others showed that administration of biosynthetic growth
hormone of rainbow trout or other fish species to juvenile fish
or oyster spat resulted in a significant growth enhancement. The
food conversion efficiency of the hormone treated animals is also
increased substantially These results point to the possibility
of studying the effect of elevated levels of growth hormone on
fish growth in different stages of development. Furthermore,
biosynthetic growth hormone could also be used to improve the
somatic growth of fish in aguaculture.
Although direct application of biosynthetic fish growth hormone
may increase the growth rates of cultured fish, several basic
studies are still required. These include: (a) methods of large
scale preparation of biologically active recombinant growth
hormone at low cost: (b) route, dosage and regimen of hormone
application: (c) effect of chronic application of the hormone to
fish: (d) safety concerns for human consuming hormone-treated
fish.
Alternative to the approach of hormone treatment is the
production transgenic fish producing elevated levels of growth
hormone. Transgenic medaka, common carp and channel catfish have
been produced in our laboratory by microinjecting or
electroporating gene constructs containing the long terminal
repeat (LTR) sequence of Rous sarcoma virus (RSV) or the common
carp b-actin gene promoter fused to rainbow trout growth hormone
cDNA These transgenic fish not only transmit the transgene into
subsequent generations but also grow substantially faster than
their non-transgenic siblings. Transgenic medaka carrying carp
b-actin gene promoter fused with rainbow trout insulin-like
growth factor (IGF) I cDNA have also been produced. Results of
these studies showed that transgenic individuals expressing IGF
gene hatched, on the average, two days earlier than their control
siblings. They also grow significantly faster than the
non-transgenic controls. These results suggest that IGF I may
also play an important role in growth and development of fish.
In order to realize the full potential of producinging fast
growing transgenic fish for commercialization, a series of
breakthroughs are required.
These include: (I) improving the efficiency of gene transfer;
(II) identifying promoters to regulate the expression : of the
foreign GH gene at appropriate levels (III) determining
physiological, nutritional and environmental factors that will
maximize the performance of transgenic individuals; and (IV)
assessing food safety and environmental impacts of transgenic
fish. (Research supported by grants from NSF, USDA and
NOAA-Maryland Sea Grant College)
Copyright 1996 Elfos Scientiae
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