By: N.Vithursha, Piume, P.Shobiya,S.Saruga & C.Shobana

University of Jaffna

Introduction

Why are GMOs produced?

GMOs in aquatic species

Benefits arising from the use of GMOs Aquaculture

Other uses of transgenic in aquatic species

Commercial significance

Conclusion

A genetically modified organism (GMO) is any organism

whose genetic material has been altered using genetic

engineering techniques.

The aim is to introduce a new trait to the which does not occur

naturally in the species.

• Genetically modified fish are used for scientific

research and as pets, and are being considered for

use as food and as aquatic pollution sensors

Increasing growth rates

Improving feed utilization

Increasing environmental tolerances

Resistance to diseases

Controlling reproduction

Improving food quality characteristics

Source : www.businessinsider.com

Atlantic salmon

Coho salmon

Chinook salmon

Tilapia

Medaka

Zebra fish

Common carp

Channel catfish

African catfish

Rainbow trout

Cutthroat trout

Goldfish

Northern pike

Loach

Sea bream

Red sea bream

Blunt snout bream

Brine shrimp

Seaweed

Sea Urchin

Abalone

Brine shrimp

Source: https://www.google.lk/#hl=en&tbm=isch&q=GM+brineshrimp+and+regular+brineshrimp&imgrc=p_Q26rdR76nI5M%3A

Maximum potential harvest and catch of wild

fish

Increasing demand for marine protein

Potential to tailor fish species for cost efficient

aquacultural production of fish proteins

Gain specific desired characters of fishes

Gene of interest is identified

Gene is isolated

The gene is amplified to produce many copies

The gene is then associated with an appropriate promoter and poly A sequence and inserted

into plasmids

The plasmid is multiplied in bacteria and the cloned construct for injection is recovered

The construct is transferred into the recipient tissue, usually fertilized eggs

Gene is integrated into recipient genome

Gene is expressed in recipient genome; inheritance of gene through further generations.

Fig: Transgenic fish production process

Research

Recreation

Food

AquAdvantage salmon

Conservation

Detecting aquatic pollution

Fish is an important source of animal protein for humans. So it

is of great significance to cultivate fast growing fish to satisfy

the growing needs of the people.

The demand for fish is increasing year on year and

the yield from capture fisheries is declining.

Aquaculture production is increasing the market ,for further

expansion in aquaculture production is likely to be very good

for many years to come.

Transgenic technology can be used for transferring

growth hormone genes into the fish in order to obtain

fast-growing, high yield “super-fish.”

Increase in growth rates can be achieved by genetic

engineering is typically 200%-600% depending on the

species, the structure of the gene construct and the

nature of insertion.

The economic gains to be made from use of such GMOs are

obvious and transgenic must ,therefore be considered as a route for

providing superior strains along with selective breeding .

The use of GH transgenic in aquaculture for maintenance of

broodstock.

There are also a number of other target phenotypes for which

transgenic offer considerable potential. These include salinity

tolerance, sterility, control of sexual phenotype, disease resistance to

specific pathogens and behavioral modifications.

One particularly interesting possibility is that of modifying the

genome to allow greater production of omega-3 fatty acids

which could bring substantial benefits to aquaculture.

Ornamental Japanese carp Work exploiting AFPs generated by

transgenic fish could become most useful in hatcheries in

future in order to preserve transgenic lines and to supply new

hatcheries and farms with suitable stocks.

Species Geneticmodification

Potentialbenefit

Actual benefit

Mud loach Triploidy To induce sterility Accelerated growth,gigantism and likely sterility

Atlanticsalmon

AFP(Anti-freeze Protein)

Increase low temperaturetolerance

Precursor AFP has only 70%activity of AFP.AFP promoter has potentialas a construct for transgenicstudies.

Carp GH(Growth Hormone)

To enhance growth Higher growth rates than thenon-transgenic controls

Tilapia GH To enhance growth transgenicline

Stable germ line transmissionin a fast growing

Rainbow trout Glucose To evaluate possibility Some positive results

Species Geneticmodification

Potentialbenefit

Actual benefit

Salmon GH with allsalmonconstruct

To enhance growth Accelerates growth by over11 fold

Catfish andcarp

Coinjection ofreporter genewith GH gene

To enhance integration

Rate of cointegration higherthan expected forindependent events

Tilapia GH To enhance growth Growth enhancement in F1animals

Zebrafish .

Luciferasegene

Use of luciferase as areporter of expression

Method comparedfavourably with southernblotting and PCR

Tilapia Lac Z gene To report on expressionlevels

Expression of reporter geneindicated that carp promoterwas 10 times more efficientthan rat promoter

Trout Chromosomemanipulationand monosex production

To increase production

Increased production

Species Geneticmodification

PotentialBenefit

Actual benefit

Tilapia GH To enhance growth

To enhance growth Up to 30 times > than nontransgenics

Tilapia GH To enhance growth

Homozygous transgenic fishproduced, growth enhanced,fertility reduced

Seabass DNA Vaccine To manage viral diseasesin farmed fish

Foreign gene transferred byinjection into the muscles

Atlantic salmon

GH Transgenic fish may havedifferent respiratory andswimming performancethan non-transgenics

Oxygen demand oftransgenics 1.6 times higherthan non-transgenics.Swimming speed nodifferent.

Tilapia YPGH( Yellowfin Porgy Growth

Hormone)

To enhance growth

Transgenics heavier andgrew faster than nontransgenics

Zebrafish Triploidyinduction

To induce sterility

Expression confirmed

Species Genetic modification

Potentialbenefit

Actual benefit

Rainbow trout Carp

alphaglobin

7/30 progeny from one of thealpha globin gene

transgenic males carried 1 of thisseven had 50 copiesintegrated into the g

Medaka AFP To increase coldtolerance

To increase coldtolerance

Atlanticsalmon

AFP To increase coldtolerance

To increase coldtolerance24/137 progeny carried theAFP gene

Goldfish Neomycinresistance gene

To assess use of gene as amarker for expression

Successful in one fish

Carp

GH To enhance growth 20/365 showed integrationand expression

Rainbow trout Chromosome Generations of Success was

The advantages of GMO in aquaculture

GH is normally produced only in the pituitary gland of animals, and it

circulates at relatively low levels in the blood. Insertion of an extra GH gene

broadens the range of tissues producing the hormone.

Various promoters are used in transgenic fish to drive growth hormone genes.

Some promoters from viruses have also been used in transgenic fish.

Recently some promoters from fish have been isolated and it is thought that the

marketplace will better accept these than viral or rodent promoters3 .

Antifreeze protein (AFP) promoter genes are naturally occurring in some fish

and have proven effective in driving expression of the GH gene in transgenic

fish

Other fish promoters used include: trout and salmon metallothionein, carp

B actin, salmon histone, and protamine from fish species

The low water temperature in winter can cause considerable stimulation to

many fish, for example, most fish cannot tolerate temperatures as low as

−1.4 to −19°C.

which is a serious problem in the aquaculture industry.

Increasing the temperature tolerance of fish would expand the options for

aquaculture.

A common gene transplant is that of antifreeze protein genes where the

intent is to develop fish that have an increased adaptability (particularly

salmonids) to very cold waters.

To avoid freezing, several fish species are able to produce antifreeze

proteins (AFPs) or antifreeze glycoproteins (AFGPs) that can interact with

ice crystals and effectively lower the freezing temperature

These proteins can also protect membranes from cold damage2, 12. So a

common gene transplant is that of antifreeze protein genes where the intent

is to develop fish that have an increased adaptability (particularly

salmonids) to very cold waters

Atlantic salmon cannot tolerate low temperatures due to the absence of the

AFP or AFGP gene in its genome, which is a problem for sea pen culture in

cold waters, eg. in the Northwest Atlantic. Therefore, there is great interest

in developing a new strain of freeze tolerant salmon in these areas.

Diseases are the main cause of economic loss in the fish farming industry.

The application of transgenic technology can effectively improve the

disease resistance of fish to substantially reduce economic losses.

The high densities in which fish are farmed make them susceptible to

diseases caused by viruses, bacteria, fungi and protozoa.

Improving the natural disease resistance of farmed fish would increase

profitability15. Yet no gene transfers to resist disease and parasitism have

been reported for fishes.

However, research is under way on the relevant major genes.

one such example is the antibacterial enzyme lysozyme14. This enzyme is

effective in the mucous of fish against a range of bacterial pathogens19 and

attempts to increase its concentration might prove beneficial.

There are also a number of other target phenotypes for which transgenic

offer considerable potential. These include salinity tolerance, sterility,

control of sexual phenotype, disease resistance to specific pathogens and

behavioural modifications.

possibility is that of modifying the genome to allow greater production of

omega-3 fatty acids

The demand for fish is increasing year on year and the yield from capture

fisheries is declining. Thus, although aquaculture production is increasing

the market for further expansion in aquacultural production is likely to be

very good for many years to come.

An OECD (1995) view was that the time scale from 1995 for GMOs in

salmon to be commercialized would be 15 years and that for tilapia would

be five years

the use of the single step genetic change represented by monosex

genetically male tilapia (GMT) in Nile tilapia (though this is not a GMO)

increased production by almost 30 percent and effectively doubled the net

income, from this source, of Philippine farmers growing it21

Raising marine fish in fresh water

Manipulating the length of reproductive cycles

Increasing the tolerance of aquaculture species to wider

ranges of environmental conditions

Enhancing nutritional qualities and taste

Controlling sexual maturation to prevent carcass

deterioration as fish age

Using transgenic fish as pollution monitors.

Creating fish that act as pollution monitors.

Enabling fish to use plants as a source of protein.

Using fish to produce pharmaceutical products.

Improving host resistance to a variety of pathogens, such as

Infectious Haematopoietic Necrosis Virus (IHNV),

Bacterial Kidney Disease (BKD) and furunculosis.

Gene technology can provide many potential benefits for the aquaculture

industry, including increased growth rates, increased temperature tolerance,

and improved disease resistance,and offer in terms of improvements in

aquaculture production, food security and generating economic benefits.

It is anticipated that further interest will develop in the future for using this

tool to improve economic efficiency for the aquaculture industry as well as

reduce pressures on wild stocks.

There are, however, some associated risks with the application of gene

technology in aquaculture.

Therefore, before the application of gene technology in aquaculture can be

readily endorsed, the potential risks need to be thoroughly assessed and the

necessary risk aversion measures developed and applied.

GMOs shows that the technology has the potential to affect a wide range of

plant and animal products and could have many consequences. It also

implies that the application of GMOs can extend beyond the food

production

the speed of genetic change made possible by genetic engineering may

represent a new potential impact on the biosphere.

Scientists, governments and the aquaculture industry have now realized the

need to inform the public about GMOs, yet there is relatively little

information available to enable the lay person to make decisions.

Widely communicated, accurate and objective assessments of the benefits

and risks associated with the use of genetic technologies should involve all

stakeholders.

Even where access to information exists, this does not guarantee that the

lay person will have sufficient knowledge and training to interpret and

make use of the technical documents.

The risks attached to the use of GMOs need to be analysed and

quantified in more realistic and reliable ways than so far is the case.

Some ethics should be consider in GMO.

Animals have the ability to suffer.

Animals have lack of moral standing, as they are irrational

Using animals in genetic engineering degrades them as creatures.

Regulatory frameworks for the exploitation of GMOs are necessary

but should be based upon reliable, objective criteria.

Hew, C.L. and Fletcher, G. L. “The role of aquatic

biotechnology in aquaculture” Canadian Journal of

Fisheries and Aquatic Sciences, 197, 2001, 191-204.

Rahman, M. A. and Maclean, N. “Growth

performance of transgenic tilapia containing an

exogenous piscine growth hormone gene”.

Aquaculture, 173, 1999, 333-346.

Maclean, N. and Laight, R. J. “Transgenic fish: an

evaluation of benefits and risks”. Fish and Fisheries,

1, 2000, 146-172.