Overview

• Preliminaries.
  • Admin.
  • Questions.

Preliminaries

Admin

• Today's note takers: FC and EL
• Welcome back from break!
• Mid-semester exams returned at the end of class.
• Welcome to Dr. Robertson from Biology!
• Upcoming extra credit:
  • Convocation, Wednesday, Extinction?

Key Points from FC

1) Definitions:

• Biotechnology: Any technology that uses living organisms for the benefit of humans.
• Genetic engineering: Direct manipulation of genetic material for practical purposes.
• Transgenic Organisms: One organism containing another organisms RNA
• Cloned Organisms: Genetically identical organisms

2) Herbicides are used to kill weeds but not the plants. The problem, however, is that weeds are becoming resistant to herbicides.

3) Utilizing genetic engineered crops create unforeseen circumstances. For instance, killing weeds--the food of butterflies--is making butterfly populations decrease by 90%.

4) Genes are moved into cells in two ways:

• Direct Transfer: Using brute force and injecting genes into the nucleus.
• Agrobacterium: Injecting disarmed TDNA into a plant that eventually cultivates hormones that causes skin to divide and becomes part of the plant. [Not quite.]

5) A different definition of technology was provided. Technology is defined as manipulating things making anything possible. [I think Dr. Robertson defined technology as making things and then said "If we can manipulate the genome, it seems like anything is possible."]

Key Points from EL

Individual genes are manipulated in genetic engineering, you can move one gene to any other organism—you can move genes across kingdoms (fungi to animals, etc). We now have the power to reshape our world in many different ways but do we have the wisdom to do this responsibly? ---Future consequences are significant

Definitions

• Biotechnology: any technique that uses living organisms or their products for the benefit of humans
• Genetic engineering: direct manipulation of genetic material for practical purposes
• Transgenic organisms: ones containing genes from another organism via rDNA techniques
• Cloned organisms: genetically identical organisms, may or may not be transgenic
• Enzymes: biological catalysts; biological molecules that make reactions go faster but are not used up in the reaction (most enzymes are proteins, some are RNA)

About 50% of approved genetically engineered plants are herbicide resistant. This is important in our chemical agriculture era, where we use chemicals to kill weeds rather than physical or mechanical labor

Transgenic crops are contaminating organic farms and their heavily regulated crops, concerns about where the onus rests (on organic or non organic farms to be mindful of where they are planting)

Weeds are starting to develop a tolerance to herbicides, so although the patent has run out on some herbicide resistant crops they are needing to find other crops to use [herbicides to use?] as they are soon going to be ineffective.

Agricultural Biotechnology

• "Biotechonlogy is a huge, umbrella term."
• Focus on agricultural biotechnology
  • First products of genetic engineering (see ahead) in the consumer market
  • We all eat genetically engineered things every day (e.g., Soybean oil)
  • "We are all [involuntary] volunteers in an ongling scientific experiment."
  • Prior to agricultural biotech, genetic engineering was used for making medicines. In that case, there was also little chance of them getting into the environment.
  • Genetically engineered crops, in contrast, are out in the environment
• We've been looking at a huge range of technologies.
  • All about manipulating things
• In biotech, we're manipulating living organisms
  • Our ancestors did "classical breeding" - crossing closely-related individuals, select best offspring, cross again, etc.
  • Breeding manipulates things at the level of DNA (even if we're doing our work at the macro level)
  • But breeding is unpredictable; you don't always get what you expect.
  • New techniques allow you to take a gene from one organism and move it to another organism, even an unrelated organism.
    • Species barriers have been erased!
    • We can move fungi genes into animals
• Genetic engineers claim that what they're doing is not much different than classical breeding.
  • They are disingeneous (sp?)
• We have significant power to manipulate our world
  • Your generation is going to have to deal with that issue!
  • Powerful ethical consequences

Definitions

• Biotechnology Any technique that uses living organisms or their products for the benefit of humans.
  • Yeast to ferment beer/wine fits within this definition
  • Yeast to make bread fits within this definition
  • So biotech has been around a long time
• Genetic engineering Direct manipulation of genetic material for practical purposes
  • What makes modern biotechnology unique
• Transgenic organism - Organisms containing genes from another organism via rDNA techniques
• Cloned organism - Genetically dientical organisms
  • May or may not be transgenic
  • Really important for Wednesday
• Enzyme - Biological catalysts; molecusel that make reactions go faster, but are not used up in the reaction.
  • Most enzymes are proteins, some are RNA
  • (Tom Cech discovered that some RNA is enzymes)

A Brief History of Modern Biotechnology

• 1953 - Watson and Crick (and ...) determined the structure of DNA
• 1973 - Stanley Cohen and Herbert Boyer developed recombinant DNA (rDNA) technology by figuring out how to transfer genes
  • Why don't we know their names as well as we know Watson and Crick
• 1980 - When biotechonlogy, built on recombinant DNA, became big business
  • Shares of Genentech on NYSE when from $35 to $89 in 30 minutes
  • Many of the early biotech companies have been aboarbed. Genentech is still around
• 1990 - Rennin, an enzyme used in cheese making, became the first rDNA ingredient approved by the FDA
  • Causes the protein in milk to coagulate
• 1990 - Companies were starting to ask for permission to field-test plants. A new portion of the FDA, biotech field-test [something] was set up

What can you do with all of these technologies?

• A tobacco plant that has the luminescense of fireflies
  • Picture is misleading - it's a 24-hour exposure
  • But an early proof of principle - You can move DNA from an insect to a plant
• Jellyfish green flourescent protein is used to highlight certain cells or tissues.
  • In keretin in chicks - we see it in their legs.

So, how do we introduce DNA into plant cells?

• Two techniques - brute force vs sophisticated

Technique one: Direct Transfer

• Strip away cell wall of plant cell
• It's now round
• Held by pipette, holding the protoplast in position
• Thin glass pipette holds DNA of interest, inject into nucleus of cell, hope that some gets incorporated
• It happens, but with low frequence
• It's "dangerous" (in that it can destroy the cell)
• Then you generate the whole plant from the one cell
• This is not an efficient way to do things

The Gene Gun - "Biolystics" (pun a balistics)

• They used to use real gunpowder
• Shoot little pellets (a few microns) coated with DNA through tissue.
• E.g., corn embryos
  • We see some dark blue spots on the embryos

Technique two: Agrobacterium-mediated transfer

• Agrobacteria already "knew" how to put their genes into other materials.
• Traditionally in the soil. E.g., Crown Gall Disease.
  • Makes the plant make food that only the agrobacterimum eats
• It took scientists awhile to figure out how to make it work.
• Ti plasmid - Where the genes for making the tumor exist
  • "Ti" = "Tumor inducing"
• Idea - Take out the part of the gene that does the tumor and put in the gene of interest.
• Useful if the target can be infected by agrobacterium
  • Only broad leaf plants
  • So not most of our grains
• Example: Small punched-out disks that have been transformed to be

Handout: A list of things that have been approved for commercialization

• A lot are for herbicide resistance
• Questions
  • Why would one develop this plant?
  • How would one engineer it?
  • What are the long-term impacts?

Category one: Herbicide-resisitance

• Isn't that a bit strange? Aren't herbicides designed to kill plants?
• Early agriculture: Pull weeds by hand
• Mechanical agriculture: Pull weeds by machine
• Chemical agriculture: Kill weeds by chemicals
• We have two kinds of herbicides
  • Broad spectrum: Kill everything
  • Narrow spectrum: Kill one kind of thing
    • Still a bit broad; e.g., broad-leaf plants vs. grasses
    • Selectivity is not absolute; Still harm crops
• Herbicides persist in the soil; carry over to the next growing season
  • If you plant corn and use a broad-leaf herbicide one season, it will harm the soybeans you might plant the next year
  • Also tend to run off into water
• Idea: Make the crop resistant to a broad-spectrum herbicide so that we can get both grasses and broad-leaves
• It's been very successful.
• Most are for Glyphosate (Round-Up)
  • Low mamalian toxity
  • Breaks down quickly in the environment - No carry over; No ground-water contamination
  • [Sam's question: How does it work]
• Another one: Bromoxynil-resistant Cotton
• Claim: Although these herbicides are expensive, this seems to be profitable.
• Note: Roundup is now off patent, but many weeds have developed a natural resistance to Roundup.
• Issue of transgenic crops cross-contaminating organic crops
  • Is it the responsibility of the transgenic farmer to prevent contamination?
  • Is it the responsibility of the organic farmer to move his/her/zir crops further away?
• Some object to this whole approach because they object to the dependence on chemicals.
• However, it doesn't look like there will be a big rush away from using these things.
  • China, South America, US, etc. are all big users
  • EU is no
• Glyphosate knocks out one enzyme in the production of a key [protein]
  • Strategy one: Find another gene for the enzyme, and put a strong promoter in front of it. We generate so much of the enzyme that even when the herbicide knocks out most, there's still enough left.
  • Strategy two: Find a related enzyme that doesn't match
• Question: Who in other countries is doing the adoption? Is it US pushing this or is it farmers choosing to adopt it?
  • Robertson suggests that generally the farmers see the benefits
• Question: How long does it take for a plant to develop resistance?
  • It depends on how much it gets exposed and such.
  • Possible in five years or so.
• Question: Corn in Africa - How do you get genes to express themselves?
  • Getting the gene in isn't difficult.
  • Getting the right controls with the gene is much more difficult.
  • In the DNA,
    • We have a coding region that specifies the protein
    • Before that region, we have a region that is called the promoter.
    • Having the right promoter in front of the gene of interest gives you the control you want
    • Should be built into the promotor

Next: Insect-resistant plants

• Environmentalists objected to herbicide-resistant plants
• Environmentalists still object to insect-resistant plants, but also don't like insecticides, so insect-resistance may be the "lesser of two [w]evils".
• How do you make insect-resistant plants? You can make them resistant to some with caterpillar stages
  • Bacillus thuringigiensis
  • Makes crystals that are toxic to insects
  • E.g., European corn borers are controlled
• Some people just use BT crystals directly.
  • Have been used directly.
  • You can watch mosquitos die.
  • When sprayed on, it lasts about a week; breaks down with water and sunlight.
• Monstanto engineered gene for the toxin into the plant. It is present the entire growing season. That means selection for resistance is very very high.
  • We're starting to see the effecs.
• Lots of pictures of protected things.
• Question: What about the effects on monarchs and other lepidotera.
  • What happens if this gets into milkweed?
  • Would the monarch larvae be affected by the pollen?
  • A worry, but no sign has been found in practice
  • Still, Monarchs are decreasing at an amazing rate.
  • Likely reason: There's so much less milkweed, which the Monarchs rely on

To be continued ...