Genetically Modified Organisms Tobacco plant with firefly gene

Bt Maize p p p 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 © 2016 Paul Billiet ODWS Image Credit: Bacillus thuringiensis

Cry gene p p 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 © 2016 Paul Billiet ODWS Image Credit: GMO Compass BT Maize

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

Disadvantages Pollinators may be killed too p Pesticide resistance in insects is rapid – but crop management could limit this p 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 p Technology expensive p © 2016 Paul Billiet ODWS

Spider silk p p p 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 © 2016 Paul Billiet ODWS © P. Billiet Aculepeira ceropegia a European orbweb spider

Spider silk p p 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 © 2016 Paul Billiet ODWS Nephila clavipes © C. Frank Starmer

Web-based kid Spider goat © Sean O'Neill p p 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

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