GENETIC ENGINEERING

OBJECTIVESDiscuss the possible benefits and hazards of gene therapy

Discuss the implications of the use of genetically modified organisms on humans and the environment

WHAT IS BIOTECHNOLOGY?Manipulation of living organisms, systems to develop products.

Field integrates knowledge from biochemistry, chemistry, microbiology and chemical engineering.

Includes genomics, recombinant gene technologies, applied immunology and development of pharmaceutical, diagnostic tests.

HISTORYUsed in agriculture, food production and medicine for thousands of years.

Bred productive animals to make stronger and more productive offspring.

Fermentation: yeast cells to raise bread dough, ferment alcoholic beverages.

Microbial cultures; bacterial cells used to make cheeses and yogurts.

APPLICATIONSMedicalDrug production (eg. Insulin, antibiotics)

Pharmacogenomics (genetic inheritance and response to drugs)

Gene Therapy (replace defective genes)

Genetic testing for diseases eg. Downs Syndrome, Amniocentesis and Chorionic Villus sampling.

APPLICATIONSChemical IndustryProduction of bulk chemicals eg. Ethanol, citric acid, acetone, butanolSynthesis of enzymes, amino acids, alkaloids

Food IndustryProduction of bakers yeast, cheese, yogurt, soy sauce, flavours, colouring agentsBrewing and wine making

APPLICATIONSAgricultureCrop yield

Reduce vulnerability of crops to environmetal stresses

Increased nutritional qualities

Improved taste, texture or appearance of food

Reduced dependence on fertilizers, pesticides

Production of novel substances in crops

Animal Biotechnology

APPLICATIONSEnvironmentBioremediation of soil and water polluted with chemicals

Treatment of sewage and other organic waste

Recovery of heavy metals from industrial sources

BIOTECHNOLOGY TECHNIQUESDNA IsolationDNA AmplificationRestriction Enzyme DigestionGel ElectrophoresisDNA SequencingDNA Cloning

GENETIC ENGINEERING AND GENE THERAPYGene therapy and genetic engineering are two closely related technologies that involve altering the genetic material of organisms.

The distinction between the two is based on purpose. Gene therapy seeks to alter genes to correct genetic defects and thus prevent or cure genetic diseases.Genetic engineering aims to modify the genes to enhance the capabilities of the organism beyond what is normal.

IMPORTANT DEFINITIONSGene segment of DNA that codes for production of a specific polypeptide

Transgene a desired gene that is artificially inserted into an organism

Transgenic organism organism that has gene(s) from another organism inserted in its genome

GENETIC ENGINEERING - FLAVR SAVR TOMATOFlavr savr tomato (Calgene) approved for commercial sale (1994)Flavr Savr Tomatoes

GENETIC ENGINEERING- DOLLYCloning of Dolly, the sheep (1996)First mammal cloned from adult somatic cellsDolly

GENETIC ENGINEERING STEM CELLSEmbryonic Stem Cells Grown (James Thomson,1998)Human Stem Cell Culture

GENETIC ENGINEERING SOYA BEANSTo improve the general balance in grain legumes, strong seed-specific gene control regions were used to increase the amount of protein in seeds.

Project was discontinued allergenetic

GENETIC ENGINEERING - POTATOEngineering high starch potatoesWhy?

Most potatoes are processed into chips or frozen french fries. For these purposes, the potatoes should ideally contain about 25% starch by weight.

Most potatoes that are processed contain only 21-22% starch

so more water needs to be evaporatedmore fat is absorbed by the potatoes during cooking

GENETIC ENGINEERING GOLDEN RICEGolden rice is similar to other varieties in their crinkly husks but the core of the grain is pale yellow, instead of pearly white. The colour is due to -carotene.

PLANT-BASED ORAL VACCINES

Scientists are working toward developing foods which would not only provide nutrition but also disease protection.

plant based vaccines or edible vaccines

TRANSGENIC FISHAtlantic salmon expressing a growth hormone transgene46 times the growth rate1020% improvement in feed conversion efficiency relative to non-transgenic salmon

shorter production times, reduced costs, and improved profitability

TRANSGENIC FISH

TRANSGENIC FISHAnti-freeze gene from Flounder fish transferred to trout (& bass) & from Pacific salmon to Atlantic salmon

new commercial opportunities for fishermen in colder waters

GENETIC ENGINEERING BT TOXINSUsing genes from a bacterium called Bacillus thuringiensis.

As part of sporulation, the bacterium, makes a crystalline structure.

This crystal is comprised of a small number of proteins that have insecticidal activity.

These proteins are referred to as Bt toxins.*

GENETIC ENGINEERING BT TOXINSVarious Bt strains are active against larvae of

lepidoptera (butterflies, moths)coleoptera (beetles)diptera (small flies, mosquitoes).

*

GENETIC ENGINEERING BT TOXINSCurrently there are 3 crops on the market that use Bt toxin expression for insect control:

Potato: introduced in 1995, where the principle insect target to control is the Colorado potato beetle Corn: introduced in 1996, to control European corn borer Cotton: introduced in 1996, to control some bollworms *

GENETIC ENGINEERING BT TOXINS

CURRENT PROJECTS AT THE UWI BIOTECHNOLOGY CENTREPlant tissue culture indigenous medicinal plant bankProduction of disease-free yam (Dioscorea sp) plantlets Improvements in micro-propagation methods

CURRENT PROJECTS AT THE UWI BIOTECHNOLOGY CENTREPlant genetic transformation Resistance to Papaya ringspot virus (PRSV) Production of papaya for human consumption, either fresh or processed Cornell University, USA & UWI, Jamaica

Papaya

CURRENT PROJECTS AT THE UWI BIOTECHNOLOGY CENTREPlant Genetic TransformationResistance to Tomato yellow leaf curl virus (TYLCV-Is) Production of tomatoes for human consumption, either fresh or processed UW-Madison, Hebrew Univ., UWITYLCV

GENE THERAPYThis is the insertion of genes into an individuals cells and tissues to treat a disease, especially hereditary diseases

Treat hereditary disorder using a copy of the functional allele

Functional allele functional proteinorganism will recuperate Only works with recessive alleles

Somatic cells or germinal cells (gametes) may be targeted

STEPS IN GENE THERAPYThe basic steps of gene therapy include:

1.the defective gene that causes a specific condition has to be identified2. the site of the affected cells in the body's tissues or organs (target cells) should be pinpointed and isolated3.Ex vivo insertion of gene into target cells 4.Reintroduction of transformed cells into individual

Use of gene therapy has been limited by the availability of safe and efficient vectors

HAEMOPHILIA AInability of blood to clot

Lack of clotting factor VIII

More common in males

Plasma contamination risk

HEMA genevectortarget cellsreplace defective gene

CYSTIC FIBROSISCystic fibrosis is caused by a mutation in the cystic fibrosis tansmembrane regulator (CFTR) gene

Mutation is most commonly caused by deletion of three bases, hence an amino acid

The mutated gene causes the production of defective CFTR protein No ion release and thick mucus production

CYSTIC FIBROSIS - SYMPTOMS

CYSTIC FIBROSISGene therapy targets the cause and not the symptoms of the defective CFTR gene found on chromosome 9

Aerosol spray that delivers normal DNA to the lung*treatment may only last for a few weeks because the epithelial cells lining the respiratory tract are shed regularly

CYSTIC FIBROSISVectors deliver a functional copy of the defective gene to cells* The gene will enter the cells, but during testing, the volunteers experienced unpleasant side effects of the virus

CYSTIC FIBROSIS

BENEFITS OF GENE THERAPYCuring disorders rather than treating

Offer highly specific treatment to target tissues without the side effects associated with chemotherapy

HAZARDS OF GENE THERAPYNeed to find safe vectors to deliver therapeutic gene to affected cells

Need to regulate expression of therapeutic gene once it is delivered to cells

If somatic cells are used in gene therapy, the alteration is not passed on to future generations

DEBATESLets revisit the objectives.

Discuss the possible benefits and hazards of gene therapy

Discuss the implications of the use of genetically modified organisms on humans and the environment

***