Transcript Lecture 35 Transgenic Fish

Lecture 35
Transgenic Fish
Steps for Making Transgenic Fish
Step 1. Decide Gene/Protein to Add.
Step 2. Decode Protein and Translate to cDNA Code.
Protein
cDNA
Steps for Making Transgenic Fish
Step 3. Prepare Gene Construct.
Protein Gene
Promoter Gene
Gene Construct
Steps for Making Transgenic Fish
Step 4. Insert Construct into Bacterial Plasmid.
Steps for Making Transgenic Fish
Step 5. Insert Plasmid in
Bacterial Strain & Make
Billions of Copies.
Steps for Making Transgenic Fish
Step 6. Isolate Plasmids from Bacteria
and Cleave into Linear Cassettes.
Steps for Making Transgenic Fish
Step 7. Insert Over 1 Million Cassettes into
Each Newly Fertilized Egg.
Steps for Making Transgenic Fish
Step 8. Incubate and Grow Out Surviving Fry.
Steps for Making Transgenic Fish
Step 9. Find the Transgenics and Select
Fish(s) with Desired Characteristics.
Steps for Making Transgenic Fish
Step 10. Breeding Program to Stabilize Transgene.
Steps for Making Transgenic Fish
Step 11. Seek Regulatory and Public Approval.
• Develop Food Safety Data
• Design Reliable Environmental Safety Measures
• Effectiveness & Target Animal Safety Data
• Convince Regulatory Agencies (CVM and Foreign)
• Convince Producers and Customers to Buy
Current Limitations
• Random insertion of short gene construct
– Variable numbers of copies inserted
– Insertion sites different for each individual
• Limitations
– Difficulty stabilizing genetic modification in a
breeding population
– Uncontrolled transgene expression, zero withdrawal
time, simple modifications only
– Insertion site effects on other genes
Current Limitations
• Need for extensive breeding program
– Before and after modification is stabilized
– Multiple generations at 2 years each
– Data on “production - fish” needed for regulatory
reviews
– Control over unlicensed, unpatented breeding
– Develop breeding biocontainment strategies
Current Limitations
• Environmental concerns about releases
– Competition with wild populations
– Gene introgression effects on wild gene pool
– Ecological disruptions due to changes in prey size and
other niche requirements
• Containment and biocontainment
– Engineering approaches are involved & unproven
– Biocontainment research still needed
Current Limitations
• Public & International Acceptance
– Attitude differs for GM animals vs. plants
– Different attitudes for optional/premium vs.
commodity food products; food vs. drugs
– Labeling & choice
– Variation among countries
– Ethical concerns stronger for animals than plants
Current Limitations
• Competition from more widely accepted
alternative approaches
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Genetic screening + selective breeding
Ploidy changes: triploid, tetraploid, etc.
Improved nutrition & management
Orally active growth promoters that can be withdrawn
pre-harvest