Genetic EngineeringPart 3

Genetically Modified Organisms

4.4.9 State two examples of the current uses of genetically modified crops or animals

• A genetically modified organism (GMO) is one that has had an artificial genetic change using the techniques of genetic engineering such as gene transfer or recombinant DNA. One of the main reasons for producing a genetically modified organism is for it to be more competitive in food production.

Transgenic plants• GM crops and GM animals are referred to as genetically

Manipulated organisms (GMO’s), also known as transgenic organisms. Their genetic material has been changed to include specific genes, usually from another species.

Flavr Savr

• In 1994, the first genetically modified food sold commercially was introduced. It was the “Flavr Savr’ a tomato that was genetically altered to stay fresh longer. This was achieved by adding another gene that blocked the gene for the production of an enzyme which caused rotting (polygalcturonase) due to various commercial problems, the tomatoes are no longer available.

Tomato salt tolerance

• Another species of tomato was modified by a bioengineering company to make it more tolerant to higher level of salt in the soil. This makes it easier to grow in regions of high salinity. soil water results in desiccation, wilting and death of the plant.

• Tomato plants have now been genetically modified to carry the gene for salt tolerance.

• The origin of the gene was a weed called Arabidopsis thaliana.• http://www.actahort.org/books/190/190_8.htm• THE DEVELOPMENT OF SALT-TOLERANT TOMATOES:

BREEDING STRATEGIES

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• . One of the claims of the biotech industry is that GM food could help solve the problem of world hunger by allowing farmers to grow food in various otherwise unsuitable conditions. Critics point out that the problem of world hunger in the world is one of food distribution, not food production.

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• Majority of the American Soybean and cotton crops are genetically modified.

• Many of these GM plants have received bacterial genes that make the plants resistant to herbicides or pests. Farmers can more easily grow these crops with far less tillage and reduced use of chemical insecticides

Rice with Retinol• Retinol deficiency:• Retinol (Vitamin A1) is essential for the development of an effective immune

system, normal vision and growth. Where a child lacks Retinol they have stunted growth and in extreme cases blindness. A serious complication arises from the combined of malnutrition, disease and retinol deficiency. The coincidence of these three conditions together is seen in some third word nations. In Zambia more than 54% of the population of children have retinol deficient diets. Even if children have sufficient food (calories) the problem is that is not a balanced diet. These children experience retarded growth for their age group and vision problems are common. Vision problems usually begin with a loss of night vision and then ultimately complete blindness. As might be expected these communities find it very difficult to support children with these multiple problems. To make matters worse diseases such as malaria and measles (known killer diseases) disable or kill large numbers of children as they have ineffective immune systems, another consequence of retinol deficiency.

Rice with Retinol

• Rice does not contain retinol or beta-carotene (used by the body to make retinol).

• Rice does contain a molecule that is normally used to make beta-carotene.

• The gene and enzymes to manufacture are missing from rice.• Genetically modified rice contains the gene for the manufacture

of beta-carotene.• Source of the gene is either Erwinia bacterium or the common

daffodil.• The transgenic rice is usually yellow in colour because of the

accumulation of beta-carotene.• This transgenic rice is then crossed with local strains of rice.

Golden rice• Rice plants store vitamin A in their leaves but not in the rice

grains. Golden rice is genetically modified by adding genes from daffodils and from a bacterium. This allows the rice to store beta carotene, a precursor of vitamin A, in the grains, which causes the yellow color. A new kind of Golden Rice has now been produced, using one gene from maize and a bacterium, which contains more than 20 times the amount of beta carotene compared to the first kind of Golden rice.

• This would provide a valuable source of vitamin A for many people and could help prevent vitamin-A deficiency- and resulting blindness- among half of the world’s people who depend on rice as their staple food. but it has been met with a lot of opposition from environmentalists and anti-globalisationists.

Golden Rice

Herbicides: Round up• Weeds growing amongst a crop use up soil nutrients that would otherwise be

used by the crop plant.• This competition of resources reduces the productivity of the crop plant and

therefore the efficiency of farming.• Herbicides can be used prior to crop planting to kills weeds.• The herbicide cannot be used after crops have been sown as they will also kill

the crop.• The major herbicide in use is called 'Glyphosate', anyone who has gardened

will know this as 'Roundup' which is the market name for the product.• However, Cotton, Corn and Soybeans have been genetically modified to

contain an enzyme that breaks down glyphosate.• This makes these crops resistant to the herbicide.• Herbicide can then be used after the crop has grown to prevent the

reoccurrence of weed competition.

• Factor IX : A human clotting factor is produces by genetically modified sheep.• The protein (factor IX) is expressed in milk from which it must be isolated before use by haemophiliacs. • A ewe is treated with fertility drugs to create super-ovulation. • Eggs are inseminated.

Each fertilised egg has the transgene injected. must be isolated before use by haemophiliacs.

• A surrogate ewe has the egg implanted for gestation. • Lambs are born which are transgenic, GMO for this factor IX gene. • Each Lamb when mature can produce milk. • The factor IX protein is in the milk and so must be isolated and purified before use in human.

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must be isolated before use by haemophiliacs.

                                             

Genetically Modified Mice

• Normally, mice do not contract polio because they do not have the receptor in their cell membranes that allows the polio virus to infect their cells. Adding this receptor, means that mice can be infected with polio and used for experiments in order to study the disease and its possible treatment and prevention.

• GM mice infected with polio will develop symptoms similar to humans with the disease

Transgenic animals

• One way of genetically engineering an animal is to get it to produce a substance which can be used in medical treatment. Consider the problem faced by some people with a blood condition in which their blood does not clot because they lack a protein called factor IX. If such people can be supplied with factor IX, their problem will be solved. The least expensive way of producing large amounts of factor IX is to use transgenic sheep. If a gene which codes for the production of factor IX is associated with the genetic information for milk production in a female sheep, she will produce that protein in her milk.

Future ?

• In the future a wide variety of genetic modifications may be possible. Perhaps inserting genes to make animals more resistant to parasites, to make sheep produce pre-dyed wool of any chosen color, to produce prize-winning show dogs, faster race horses…

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• Bt corn is genetically modified maize. A gene from Bacillus thuringiensis (Bt) has been incorporated into the maize DNA. As a result, the plants produce a toxin that makes them resistant to insects. Bt crops are grown in the US

• Bt corn contains a gene from the Bacillus thuringiensis which produces a protein that is toxic to specific insects, in particular the European corn borer (ECB) which is also found in the US.

• The ECB through stems and leaves of the corn plant and will damage vascular bundles and disrupt the transport of water and nutrients through the plant. It can also weaken the stems and leaves so that the plant or leaves may break. Only a small part of the damage is caused by the ECB eating the corn directly.

4.4.10 Discuss the potential benefits and Possible harmful effects of one example of genetic modification

• The damage caused by the ECB is much reduced.• Bt corn is slightly more expensive, but the difference is less than one extra

application of insecticide.• Non-Bt corn needs to be checked often for signs of ECB- less checking needed

for Bt corn.• Less insecticide needed means less impact on the environment and lower

health risks for the workers.• Seems to reduce the infection with fungus so myotoxins levels are lowered.

Myotoxins are difficult to remove by cooking/freezing and may go into the food chain and may be found in meat of animals which ate the infected corn. Myoptoxins can be a hazard to human and animal health.

• Less pest damage and therefore higher crop yields to help to reduce food shortages.

• Less land needed for crop production, so some could become areas for wildlife conservation.

Harmful effects of Bt corn

• Insects may develop resistance to Bt toxins because they are exposed to it all the time.

• Resistant insects also make Bt spray useless as insecticide (Bt spray is considered to be relatively safe for humans and environment)

• It is difficult to prevent pollen (with the Bt gene) from travelling outside the field where the Bt corn is grown.

• It may fertilize non-Bt corn e.g. organically grown corn which can then no longer be sold as organic corn.

• It may fertilize wild relatives and make them more resistant to insects and have them dominate the niche they live in. Populations of wild plants might be changed. Cross-pollination will spread the Bt gene into some wild plants but not others. These plants would then produce the Bt toxin and have an advantage over other wild plants in the struggle for survival. This would result in loss of biodiversity

Click 4• The benefits of GMO include:• Increased yields particularly in regions of food shortage.• Yields of crops with specific dietary requirement such as vitamins and

minerals.• Crops that do not spoil so easily during storage.• GM animals produce similar effect including higher meat yields.• The disadvantages or concerns about GMO usually can be found:• The foods (animal and plant) are considered un-natural and unsafe

for human consumption. • There is a risk of the escape of 'genes' into the environment where

they may be passed to other organisms with unknown effects.

• Humans or farm animals that eat the genetically modified maize might be harmed by the bacterial DNA in it, or by the Bt toxin.

• Insects that are not pests could be killed. Maize pollen containing the toxin is blown onto wild plants growing near the maize. Insects feeding on the wild plants including monarch butterfly caterpillars, are therefore affected even if they do not feed on the maize.

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Is genetic engineering a good or bad thing? Benefits, promises, and hopes for the future

• GM crops will help farmers by improving food production.• GM crops which produce their own pest-control will be beneficial to

the environment because fewer chemical pesticides will be needed.• Using GMO’s to produce rare proteins for medications or vaccines

could be, in the long run, less costly and produce less pollution than synthesizing such proteins in laboratories.

• Farmers can be more in control of what crop or livestock they produce. There is always some randomness in breeding; genetic modification makes the process less of a gamble. It is also much quicker than selective breeding.

• The multinational companies who make GM plants claim that they will enable farmers in developing nations to help reduce hunger by using pest-resistant crops or GM plants which need less water.

Harmful effects, dangers and fears.

• No one knows the long term effects of the GMO’s in the wild. Efforts to keep the GM plants under control in well-defined areas have failed and pollen from crop has escaped to neighboring fields. Genes from GM plants could be integrated into wild species giving them an unnatural advantage over other species and an ability to take over the habitat.

• Bt crops which produce toxins to kill insects could be harmful to humans because, unlike chemical pesticides which are only applied to the outer surface the toxins are found throughout the plant.

• There are risks for allergies; if someone is not allergic to natural tomatoes but is allergic to GM tomatoes, they will need to know which one they are eating. But there is no difference in the outward appearance of the fruit and food labeling is not always clear.

Issues raised by Genetic Engineering

• Will a gene, added to a genome, function in an unforeseen manner-perhaps, for example, triggering some disease in the recipient?

• Might an introduced gene for resistance to adverse conditions get transferred from a crop plant or farm animal into a weed species or to some predator?

• Is it possible that a harmless organism such as the human gut bacterium E.coli might with recombinant DNA technology, be transformed into a harmful pathogen that escapes the laboratory and infects the population?

• Is there an important overriding principle that humans should not ‘change nature’ in a deliberate way?

• Genetic engineering is a costly technology, mostly beneficial to the health and life expectancy of people of developed nations. If the funds were made available for more basic problems of housing, health and nutrition in less developed countries instead, vastly more humans would benefit immediately.

Bt Corn

TOK are GM crops safe?

• Genetic modification is illegal in some countries but widely encouraged in others. There are risks that must be carefully considered and weighed against the potential benefits.

• Would the more than 250,000 people who go blind each year from Vitamin A deficiency welcome genetically modified ‘golden rice, in which each grain contains Vitamin A, or protest against its development?

• How seriously are the concerns of those opposed to genetic modification taken?

• Does protesting make the world a better place to live in?• How should we decide how we use knowledge?

4.4.6 Outline three outcomes of the sequencing of the complete human genome

• Dr Francis Collins and Dr Craig Venter, the leaders of the Human Genome Project.

• The human genome project is an effort to map the human genome in total detail by determining the entire nucleotide sequence of human DNA. Because the genome of an organism is a catalogue of all the bases it possesses, the Human Genome Project helped to determine the order of all the bases A, T, C and G in human DNA.

• The human genome can be thought as a map which can be used to show the locus of any gene on any one of the 23 pairs of chromosomes.

• In sex linked diseases, it is relatively easy to determine which chromosome the gene responsible for the disease is found on; often the locus is on the X chromosome.

• The ultimate objectives of HGP were to discover the location of each human gene and the base sequence within its DNA structure.

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• Another advantageous use of the human genome is the production of new medications. This idea involves several steps.

• Find beneficial molecules which are produced naturally in healthy people;

• Find out which gene controls the synthesis of a desirable molecule.

• Copy that gene and use it as instructions to synthesize the molecule in a laboratory;

• Distribute the beneficial molecule as a new medical treatment.

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• By comparing the genetic makeup of populations around the world, countless details could be revealed about ancestries and how humans have migrated and mixed their genes with other populations over time

Benefits of human genome

• Provides insight into fundamental mysteries as embryonic development and evolution.

• For human health, the identification of genes will aid in the diagnosis, treatment, and possibly prevention of many of our more common ailments, including heart diseases, allergies, diabetes, schizophrenia, alcoholism, Alzheimer’s disease and cancer. Hundreds of disease-associated genes have already been identified as a result of the project.

• The production of medicines (based on DNA sequences) to cure diseases and/or genetic engineering to remove the genes which cause the disease.

• To determine fully which genetic disease any individual is prone to (genetic screening leading to preventive medicine);

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• The DNA sequences from the HGP are deposited in a database available to researchers all over the world via the Internet. Scientists use software to analyze the sequences. The most exciting challenge is figuring out the functions of the genes and how they work together to direct the structure and function of a living organism.

• Make use of the handout on HGP given to you from IB Biology Text book by C.J.Clegg (Page numbers 131-133)

Outcome of the HGPClick 4 Biology

• identify all the approximate 30,000 genes in human DNA. • determine the sequences of the 3 billion chemical base pairs that

make up human DNA. • store this information in database. • improve tools for data analysis. • transfer related technologies to the private sector. • address the ethical, legal, and social issues (ELSI) that may arise

from the project. • To help achieve these goals, researchers also are studying the

genetic makeup of several nonhuman organisms. These include the common human gut bacterium Escherichia coli, the fruit fly, and the laboratory mouse.