Genetics and Biotechnology

1. Genetics and Biotechnology

2. Biotechnology • A group of many technologies that use living cells or their processes to make products or solve problems • Used in basic and applied research • Used in developing products for the marketplace

3. Medicine Plant Science Food Science Genetics Biochemistry Statistics Mathematics Engineering Computer Science Philosophy (Ethics) Fields Contributing to Biotechnology

4. Cloning Genes Whole organisms Drug production Insulin Disease prevention HIV test Blood-type test Pregnancy test Applications of Biotechnology

5. Applications of Biotechnology • Genetic engineering • Gene therapy • Gene discovery • Human disease genes • Alzheimer’s • Breast cancer • Huntington’s Disease • Plant genes • Carotenoid synthesis • Oil production

6. Genetics Primer • Gene: basic unit of heredity • Protein: product of a gene • Genotype: genetic makeup of an individual (sum of all the genes) • Phenotype: observed traits of an individual, due to expression of its genes and interaction with the environment

7. Genes are made of DNA Cell • DNA is a ladder-like double helix. • Rungs of the ladder are made of pairs of four bases: A, C, G, T Nucleus Sugar-phosphate backbone Bases

8. Genes code for proteins • The sequence of bases in the DNA of a gene contains information to make a protein • The DNA code is triplet • Each triplet codes for an amino acid • Example: the sequence TTG is the code for the amino acid tryptophan • Proteins are built from amino acids • Transferring the information from DNA to protein is called gene expression expression gene (DNA) protein

9. Gene expression is regulated • The same set of genes is contained in (nearly) every cell of an organism, but... • Not all genes are expressed in every cell • Genes for helping plants absorb minerals from the soil are expressed in the root • Genes for plant oil production are expressed primarily in the embryo • Genes for milk production in mammals are expressed in the mammary glands

10. Proteins have many functions • Transport: hemoglobin carries oxygen in blood • Structural: collagen holds cells together • Receptor: receives signals sent to cell • Regulatory: control gene expression • Enzymes: catalyze chemical reactions in the cell

11. Proteins govern traits An organism’s appearance and qualities are the products of gene expression expression Genes Proteins = Traits

12. Variation in traits is due to different alleles Different forms of a gene (called alleles) can lead to different phenotypes (expression of traits) Gene A Trait (Fruit Color) Allele 1 Purple Allele 2 White

13. Transmitting genes to offspring • Traditional mating or breeding • Female contributes half her genes through egg • Male contributes half his genes through sperm • Offspring have half their genes from mom and half from dad • Genetic engineering • Donor contributes one or a few genes • Offspring have all their own genes plus one or a few genes

14. (cross) “Breeding” vs. “Engineering” TRADITIONAL BREEDING Donor Commercial variety New variety (many genes transferred) = Desired gene Desired gene GENETIC ENGINEERING Commercial variety New variety Desired gene (one gene transferred) = (transfer) Desired gene

15. Terms • Transgenic organism • One in which a gene has been introduced or modified by genetic engineering • Genetically engineered organism (GEO) • Same as transgenic organism • Genetically modified organism (GMO) • Erroneously assumed to be same as transgenic organism • Actually, organisms can be modified genetically by “breeding” or by “engineering”

16. Applications of Biotechnology • Agricultural food production • Improved production • Disease resistance • Herbicide tolerance • Insect resistance • Improved food quality • Modified oils • Delayed fruit ripening • Nutritional enhancement

17. Insect resistance: Bt corn • Plants contain a gene from the soil bacterium, Bacillus thuringensis • Bacillus thuringensis strains contain genes for a series of proteins called Bt toxins • Bt toxins: • are toxic to certain insects, including European corn borer • break down rapidly in the soil • are not harmful to mammals or birds

18. Concerns • Environmental concerns • Effect of Bt corn on monarchs • Invasion of natural plant populations by genetically engineered crops • Food safety concerns • StarLink in taco shells • Farmer’s point of view

19. Impact of Bt corn on monarch butterflies • In 1999, an article* was published stating that pollen from Bt corn plants could kill monarch butterfly larvae • Assertion: planting of Bt corn poses a risk to monarch butterflies • Concerns were raised and more research was done * Losey et al., 1999. Transgenic pollen harms monarch larvae. Nature 399:214.

20. Are the data reproducible? Does the lab represent the field? What controls should be included? What does monarch reproductive behavior say about the lab experiment? Is all Bt corn the same? How does Bt corn compare to impact of current insect control methods? What is the greatest documented threat to monarch survival? Is the monarch endangered? Questions asked

21. Findings • Some varieties of Bt corn produce pollen with toxic levels of Bt; these are being phased out of commercial production in favor of varieties do not produce Bt in the pollen • In most parts of the country where corn is grown, the time of monarch larvae feeding does not coincide with the time that corn pollen is shedding

22. More Findings • Pollen does not accumulate on the same leaves as monarchs lay their eggs, even when milkweed plants (preferred host) are found in corn fields • The greatest threat to monarchs is predation. • Overall conclusion: Bt corn does not pose a significant risk to monarch butterflies Gatehouse et al., 2002. The case of the monarch butterfly: a verdict is returned. Trends in Genetics 18:249-251.

23. The taco shell controversy • A variety of Bt corn called StarLink was detected in taco shells and other foods • StarLink produces a variety of Bt toxin that had not been tested for allergenicity in humans • Therefore, StarLink was approved by FDA only for animal feed and not for human consumption http://www.cbsnews.com/stories/2000/09/18/tech/main234240.shtml; accessed 17 June 04

24. Risks to natural plant populations • Survival / reproduction of genetically engineered crops outside cultivation • Pollen flow of genetically engineered crop to wild relatives, hybrid formation, survival and reproduction • Spread and persistence represent possible economic or environmental harm Wolfenberger and Phifer, 2000. The ecological risks and benefits of genetically engineered plants. Science 290:2088.

25. Farmer’s view • 45% of farmers had higher yields in fields of Bt corn than conventional corn in 1998 • Nearly 26% of farmers using Bt corn reported a decrease in pesticide use • Even considering additional cost of planting Bt corn (~$15/acre), Bt corn should pay off in 7 out of 10 years • Bt corn can also reduce occurrence of Fusarium ear rot (spread by borers)

26. Applications of Biotechnology • Agricultural food production • Plants • Animals • Medical treatment • Biopharmaceuticals • Gene therapy • Environmental detoxification • Bioremediation • Phytoremediation

27. Animal production • Improving production through cloning • Strategy: Good producer Clones (identical copies) Interbreed

28. Cloned Animals Dolly and Mom Calf Clones

29. Medical treatments:Biopharmaceuticals • Biological factors administered as drugs • Methods of production • purification from animals • purification from genetically engineered organisms • Examples • insulin, for diabetes • human growth hormone, for genetic deficiencies • clotting factors for types of hemophilia

30. Using animals for pharmaceuticals:Molecular “pharming” Proteins from milk of transgenic animals Lactoferrin Clotting factor IX Insulin-like growth factor Iron supplement in infant formula Treatment of hemophilia Treatment of diabetes

31. Medical treatments:Gene therapy David Vetter, the “Bubble Boy” Severe Combined Immune Deficiency

32. Applications of Biotechnology • Agricultural food production • Plants • Animals • Medical treatment • Biopharmaceuticals • Gene therapy • Environmental detoxification • Bioremediation by bacteria • Phytoremediation by plants

33. Environmental detoxification:Phytoremediation • Types of contaminants detoxified • heavy metals • radionuclides • organic compounds • petroleum products • explosives • Mechanisms plants use to detoxify • Accumulating heavy metals • Breaking down organic compounds • Volatilizing organic compounds

34. Enzymes in plant roots break down (degrade) organic contaminants. The fragments are incorporated into new plant materials. Phytodegradation contaminant

35. Phytoaccumulation • Nickel is removed from soil by moving into plant roots, stems, and leaves. • Plant is then harvested and disposed of, and site is replanted until nickel levels are acceptably low.

36. Genetics and Biotechnology