1. Genetically Modified Organisms
Tobacco plant with firefly gene © Keith Wood (of DeLuca lab) for Science Magazine 1986
© 2016 Paul Billiet ODWS

2. Bt Maize
Bacillus thuringiensis produces a bacterial toxin (Delta-endotoxin)
The bacterium has been used as an insecticide since 1938
It stops the insect from feeding by attacking the insect gut lining
Image Credit: Bacillus thuringiensis
© 2016 Paul Billiet ODWS

3. Cry gene The toxin is produced by the Cry gene
Found on plasmids in the bacterium
The gene is added to the genomes of crop plants using a bacterium that forms root nodules in plants (Agrobacterium tumificiens)
Bt crops produced from 1996 onwards: maize, potato, cotton, soybean
Image Credit: GMO Compass BT Maize
© 2016 Paul Billiet ODWS

4. Advantages
Only insects attacking the crop will be poisoned Environmentally friendly
All tissues are protected even the roots
Biodegradable – does not accumulate in the food chain
© 2016 Paul Billiet ODWS

5. Disadvantages Pollinators may be killed too
Pesticide resistance in insects is rapid – but crop management could limit this
Pollen grains could spread the gene to wild relatives of the crop plant – but terminator genes could prevent this - but terminator genes considered unethical in developing nations
Technology expensive
© 2016 Paul Billiet ODWS

6. Spider silk
Spider’s silk is 5 times stronger than a thread of steel of the same thickness 3 times stronger than Kevlar (carbon fibre)
Spiders are carnivores and cannot be raised
Transgenic animals can produce the spider protein
Aculepeira ceropegia
a European orbweb spider
© P. Billiet
© 2016 Paul Billiet ODWS

7. Spider silk
The gene for spider silk protein was isolated from the golden orb weaver (Nephila clavipes)
Not easy, it is a fibrous protein so it has a very repetitive gene sequence
Nephila clavipes © C. Frank Starmer
© 2016 Paul Billiet ODWS

8. Web-based kid
Spider goat © Sean O'Neill
Gene (plus regulator genes) inserted into goat mammary gland cells
Genetically transformed cells could be made to secrete spider silk protein
Transformed goat cells fused to enucleated oocyte
Genetically transformed goat embryos produced
© 2016 Paul Billiet ODWS

9. Goat grows up, females produce spider silk protein in their milk
Silk protein purified
Extruded through nozzle to produce silken thread
Not easy as the conditions are not quite the same a spider’s spinneret
Transformed goats can be bred together perpetuating the trait
© 2016 Paul Billiet ODWS

10. Applications Super strong surgery thread Artificial ligaments
Light bullet proof body armour
Biodegradable fishing line
© 2016 Paul Billiet ODWS