• Diversity of species on Earth
• Invasive/exotic species
• Mass extinctions
• Genetically modified organisms

What is done during genetic modification of organisms? Genetic material from one organism is inserted in the genetic material of a completely unrelated organism. This also happens in nature, and has been of prime importance during evolution.

Genetic engineering:

• Take genetic material (e.g, from bacterium, Bacillus thuringiensis) the function of which is known, e.g., the genes which code for making Bt proteins
• Bt proteins are toxic to many insects
• Insert gene from bacterium into plants
• Transfers possible between unrelated organisms (does not always work…)

This is possible because all organisms on Earth share a genetic information system

Note: Bacillus thuringiensis makes strong insecticide, which is also used in a 'normal' (not genetically engieered) way. Bacterial powder sprayed on plants

• Archaea
• Bacteria
• Eukarya (containing plants, animals, unicellular eukaryotic organisms)

During  evolution of eukaryotes from prokaryotes: genetic materials from various different groups of prokaryotes were combined.

1. Symbiosis of Archaebacterium with purple bacterium: the latter then  becomes the mitochondrion (small structure within the cell, deals with energy use by the cell, and has its own, distinct DNA). This process is called endosymbiosis, because one symbiont ends up within the other partner.
2. Symbiosis of 1) with cyanobacterium; the latter becomes chloroplast which is the structure in plant cells that photosynthesizes
3. Colonies of 1) become animals, colonies of 2) become plants

Recently revised view of evolution of 3 domains:

There has been much more  transfer of genetic material between prokaryotes, than only the transfer in the endosymbiosis. This has been called lateral gene transfer , and is common between various groups of prokaryotes only; it does not occur in eukaryotes.

• In Eukaryotes: gene transfer only from parent to offspring during sexual reproduction (pre technology)
• In Prokaryotes genetic transfer common between individuals, even non-related (resistance to antibiotics in bacteria)

How do bacteria transfer genetic material to each other?

• Prokaryotes have no nucleus.
• Bacteria: somatic genome, circle of double-stranded DNA; defines type of bacterium, and is necessary for the cell.
• Optional: smaller circles of DNA: plasmids. Genes on plasmids allow survival under unusual conditions.
• Bacterium duplicates plasmid, gives a  copy to another cell via a thin tube called a pilus.

It is because of this gene transfer that such deadly, antibiotic resistant bacteria have developed so rapidly, especially in hospitals.

Bacteria can also transfer their genetic material to Eukarya:

Transfer of genetic material from bacterium to plant (different Domains)

• Agrobacterium tumefaciens: causes crown gall disease in many crop plants (galls = tumors)
• Transfers some of its genetic material from a plasmid through a pilus into plant cells

Sutdy of crown gall disease was of major importance for genetic engineering; plasmids of this bacterium are much used by humans to transfer genetic material.

• New way to manipulate heredity, move genes across species boundaries, make novel organisms
• Old way: domestication of plants and animals

Domestication: genetic material in plants and animals has been long manipulated. Darwin studied pigeon breeding, and compared natural selection with selection by humans, in domesticated animals and plants. In domestication, one can only select 'whole organism', i.e., whole genome. Domestication does produce 'unnatural organisms' that could never survive in the wild. New organisms and new genetic combinations are generation by hybridization in plants, but hybrids can be bred only between related species. It is thus impossible to combine genetic material from unrelated organisms.

• Potato: virus, chicken and silk moth genes for disease resistance; wax moth virus for bruising resistance; bacterial genes for herbicide tolerance
• Tomato: flounder genes for frost resistance; virus genes for disease resistance; bacterial genes for insect resistance

• Electro- and chemical poration: make holes in cell membrane by chemicals or electric currents
• Microinjection: injecting new gene (glass needle) into the recipient cell
• Bioballistics: metals slivers coated with DNA, ëshotí into cell
• Recombinant DNA (uses biological vectors like plasmids or viruses)

Use of bacterium plasmids (or viruses):

• If bacterium takes up the plasmid with inserted material, it will make the protein for which the gene codes. Example: insulin production
• EcoRI: enzyme which 'cuts' DNA will cut the plasmid circle, insert new DNA

1. Threats to human health
2. Disruption of natural ecosystems
3. Threats to agriculture

• It can not be predicted WHERE in the chromosomes a new gene is inserted (structural/regulatory genes). Genetic material contains genes which are regulatory, i.e., they do not tell the cell to make a protein (which is what structural genes do), they tell the cell when to switch on or switch off a process. Insertion of new genes within a structural gene region may change the regulatory processes, and a plant that makes very low levels of toxics may start to make much higher levels, or in other parts of the plant.
• One gene can affect more aspects of an organism than one (pleiotropy), additional aspects unknown.
• Two genes combined may have a different effect than either of them separate; if one is changed, effect not predictable.

• New allergens: soybeans with Brazil-nut proteins cause reactions in individuals allergic to Brazil nuts
• Antibiotic resistance genes used as ëmarkersí
• Production of new toxins (or toxins in parts of plants that were non-toxic): often it can not be predicted WHERE in the chromosomes a new gene is inserted

• Weeds (in nature as well as around crops): plants that overtake ecosystems (as in invasive species do)
• Gene transfer to wild relatives (pollen in plants)
• Indirect: change in herbicide use
• Plants used to produce chemicals could poison wildlife

3. Agriculture: similar to threats to ecosystems:

• Weeds (in nature as well as around crops): plants that overtake ecosystems (as in invasive species do)
• Unintended effects (e.g., toxins in parts of plants where they are now absent; toxins at higher levels; more vulnerability to some insects)
• Inserted genese could be picked up by viruses

• Weight financial vs. societal benefits
• Possible to make more nutritious crops, crops with vitamins in short supply in some regions
• Benefits of plants that tolerate chemical herbicides? Give fruits long shelf life?

• Delayed-ripening tomato (1994) FlavrSavr™Tomato
• Virus-resistant squash (1994)
• Potatoes, canola, more tomato, corn, soy, cotton

Genetically modified food: how common?

28 March 2002: Prospective planting figures for genetically engineered (GE) crops in the US released by the United States Department of Agriculture (USDA): plantings of

1. GE soya from 68 to 74 percent
2. GE cotton from 69 to 71 percent
3. GE corn from 26  to 32 percent

• Genetically modified food is here, it is common, it is global: all that has happened without real public debate.
• Food items containing GMO are not labeled as such, consumer has little choice.
• How regulated? Companies marketing also present testing data.

News Item from 'DAILY GRIST', 23 Apr 2002. Environmental news from GRIST MAGAZINE, a project of Earth Day Network.

LETTING THE GENE OUT OF THE BOTTLE

Delegates from almost 200 countries are meeting in The Hague, Netherlands, this week to discuss the future of genetically modified organisms. Their challenge is to strike a balance between the fondest hopes of the multi-billion dollar biotech industry and the deepest fears of environmentalists, who worry that GMOs could adversely affect ecosystems and human health. During the conference, environmentalists plan to call for a moratorium on planting genetically modified crops near native species, to prevent contamination of the natural gene pool. The last major international meeting on GMOs, held in Colombia in 1999, resulted in the Cartagena Protocol on Biosafety, which was designed to ensure the safe transfer, handling, and use of transgenic organisms. The protocol has been signed by more than 100 countries (not including the United States, unsurprisingly) but must be ratified by at least 50 to take effect. Those ratifications are expected to occur during the World Summit on Sustainable Development, to be held in Johannesburg, South Africa, later this year.

straight to the source: BBC News, Geraldine Coughlan, 22 Apr 2002

Further information in Genetically Modified Organisms:

• Union of Concerned Scientists
• New Scientist story (21 january 2006)