1 Biotechnology and Genetically Modified Foods Introduction: In this workshop you will create a transgenic plant using the concepts, not the actual technology, of DNA recombination. First, you will evaluate the use of transgenic crops from the perspectives of the consumer and the producer, then you will insert a gene into a bacterial plasmid, to make a new transgenic plant. Key concepts: - The traits expressed in an organism can be altered using genes from other organisms. This can be accomplished by DNA recombination. - Transgenic crops usually have quantifiable economic advantages, but unquantifiable environmental disadvantages. What’s due 1. D2L Workshop 2 “quiz” over terms and concepts p.1-4 - 5 points 2. Chocolate-flavored cherry plasmid DNA p.4-7 - 5 points Hand-in at the beginning of workshop 3 next week. This lab has been adapted from ‘Dining on DNA’. See also: http://www.who.int/foodsafety/publications/biotech/20questions/en/ http://www.newscientist.com/channel/opinion/gm-food/ Introduction Genetic modification (GM) is a relatively new and controversial technique that improves the traits of organisms used for human usage. Originally identified as a genetic process by which genes for antibiotic-resistance were passed from one bacterium to another, the process was soon adopted to artificially produce crops with desirable traits such as pest-resistance. Although the process of gene-selection has been used by humans for 10,000 years for crop and animal domestication, and increased mutation rates have been used for nearly a century, the GM technique produces horizontal gene transfer between unrelated organisms. Potential benefits include unique qualities of organisms and reduced environmental impact from pesticide use. Potential hazards include the potential transfer of genes to unintended organisms, and unforeseen results of this process. By 2006, 252 million acres of GM crops were being grown in 22 countries 2012; the United States being the global leader, with over half of the global cultivation. Some countries (UK) do not currently permit cultivation of GM crops, but the cultivation of GM crops in developing countries is expected to undergo exponential increase. Over 100 different varieties of 50 different crops are available for cultivation, but some GM crops are no longer cultivated, such as the first GM food, “FlavrSavr tomatoes (DSCS CSU, 2004)” Reference Cited Department of Soil and Crop Sciences Colorado State University. Transgenic Crops Currently on the Market. http://cls.casa.colostate.edu/TransgenicCrops/current.html. Last updated March 8, 2004; date viewed February 3, 2008. Update: Fall 2012 Debate topic for next week: GENETICALLY MODIFIED FOOD2 Flavr SavrTM Tomato In the United States, tomato-lovers spend $4 billion on tomatoes each year (including salads, pastas, sauces, ketchups, and soups). American consumers expect to be able to purchase fresh tomatoes all year long, so during cold months tomato growers have a hard time keeping up with the demand. Over the winter, tomatoes grown in southern states are picked while green and shipped to northern states. The tomatoes are then reddened and ripened in containers filled with ethylene gas. Northern consumers complain that ethylene-ripened tomatoes do not have the “backyard summertime” flavor of those available in grocery stores during warm months. Another problem is that because the tomatoes were picked early, they did not receive enough sun and nutrients from the soil to gain vine-ripened flavor and texture. What’s more, ethylene-ripened tomatoes start rotting within 4 –5 days, so many tomatoes spoil before they can be sold. Pectin, a naturally occurring fiber substance, is what gives tomatoes their firmness. Tomatoes have a gene that codes for an enzyme known as polyG. PolyG actually chews up the pectin in the tomato and causes it to become softer and mushier. Calgene, Inc. genetically engineered a tomato by turning off the gene that codes for polyG. They did this by introducing an ‘antisense’ version of the polyG gene into the tomato. When the antisense gene is introduced, it attaches to the polyG gene, which can then no longer code for the polyG enzyme. The new tomato does not soften as quickly and can stay on the vine longer to gain nutrients and more flavor. Things to think about: - Are consumers going to pay more for this tomato? - Is this a worthwhile use of technology? - Could this gene transfer affect other traits of the tomato? “Golden” Rice A majority of the world’s nutrient deficiencies concern iron and vitamin-A. Iron deficiency affects approximately 3.7 billion people, most of which are women. Anemia, an illness related to iron deficiency, impairs immunity and reduces physical and mental capacities. Even mild anemia in children can impair intellectual development. Vitamin-A deficiency affects about 7% of the population, mostly children (up to 400 million children). Vitamin-A deficiency makes children vulnerable into infection and worsens the course of many infections. It is also the main cause of blindness among children in developing countries. Each year there are more than one million deaths associated with vitamin-A deficiency. The important compound in producing vitamin-A is beta-carotene, which is what makes carrots look orange. Rice plants produce beta-carotene, but only in the leafy parts of the plant and not in the rice grain that is consumed by humans. Rice is also high in phytic acid, which is an inhibitor of iron absorption in the human body. Scientists added three genes to a type of rice to make it produce beta-carotene within the rice grain. Two of these were from the daffodil and one was from a bacterium. The rice grains now contain enough beta-carotene to meet the total vitamin-A requirement of a human diet and, perhaps not surprisingly, they are now orange-colored! To double the iron content in rice, the research team added a ferritin gene from a bean. Ferritin is an iron storage protein found in many animals, plants, and bacteria. They decreased the amount of phytic acid in the rice by introducing a phytase gene that degrades the phytic acid, thus increasing iron absorption during digestion.3 The scientists’ goal is to distribute the rice free of charge. Local rice breeders can then transfer these new characters of the rice into