GMO notes

 

  • There is a small minority of biologists raising questions about GM safety
    • Inserted genes can be transformed by several different means, and it can happen generations later, resulting in potentially toxic plants slipping through testing.
    • Funding for plant molecular biology comes mostly from companies that sell GM seeds, and favors researchers who are exploring further ways to use GM tech
      • biologists who point out risks associated with GM crops have their credibility viciously attacked, which leads to silence on the subject
  • Concerns over health risks so far remain theoretical
  • GM crops has lowered the price of food; increased farmer safety by allowing them to use less pesticides; raised the output of corn, cotton, and soy by 20-30%
  • GM crops could grow in dry and salty land, withstand high and low temperatures, and tolerate insects, disease, and herbicides
  • GM acceptance elsewhere
    • Nearly all the corn and soybeans grown in the US are GM crops, but only two crops—Monsanto’s maize and BASF’s Amflora potato—are accepted in the EU, but 10 EU countries have banned Monsanto’s maize
      • several new GM corn strains have been voted down
    • Much of Asia (including India and China) has yet to approve GMOs
    • Several African countries have refused to import GM food despite lower costs
      • Kenya has banned them altogether
    • No country has definite plans to grow Golden Rice, despite its potential to prevent death and blindness
    • only a tenth of the world’s cropland includes GMOs; four countries—US, Canada, Brazil, and Argentia—grow 90% of it
    • European resentment of American agribusiness influences global perspective
  • Humans have been breeding crops—and therefore altering their genomes—for millenia
    • wheat has long been a strictly human-engineered plant
    • for 60 years, scientists have been using “mutagenic” techniques to scramble the DNA of plants with radiation and chemicals, creating strains of wheat, rice, peanuts, and pears that have become agricultural mainstays
    • difference is that breeding and mutagenic techniques result in large swaths of genes being swapped or altered, while GM tech enables scientists to insert a single gene from another species of plant, or even bacterium, virus, or animal
      • viruses have been inserting their DNA into the genomes of crops, humans, and other animals for millions of years, and deliver the genes of other species too (human genome is loaded with sequences that originated in viruses and nonhuman species)
      • Changing a single gene, on the other hand, might turn out to be a more subversive action, with unexpected ripple effects, including the production of new proteins that might be toxins or allergens.
  • Some scientists say that objections to GMOs stem from politics rather than science, motivated by an objection to large multinational corporations having enormous influence over the food supply

https://www.scientificamerican.com/article/the-truth-about-genetically-modified-food/

more GMO notes

Are GMOs safe?

  • no adverse health effects among consumers have been found
  • about 90% of scientists believe GMOs are safe, but only slightly more than 1/3 of consumers think the same
  • commonly expressed concerns (unwanted changes in nutritional content, creation of allergens, and toxic effects on organs) have not been clearly demonstrated yet; but benefits (higher yield, lower toxins) have been well-established
    • yields of corn, cotton, and soybeans are said to have risen by 20-30%
    • animal health and growth have improved on genetically engineered feed
    • could greatly increase food supply
    • Golden Rice: GMO that has more vitamin A than spinach and could prevent blindness and more that a million deaths a year in African and Asian countries
      • has genes added to it which allow it to produce beta-carotene

 

 

Citizen Science wk 4 readings

Synthetic Biology: Applications, Benefits, and Risks

  • renewable energy: biofuels are derived from biomass from plants, animals, and organic waste
    • methods of harvesting energy: burning, chemical treatment, biodegradation
    • ethanol is the most common (corn or sugar cane); biodiesel is made from vegetable oils, animal fats, or recycled restaurant grease
      • ethanol includes inefficiencies and energy costs for production, concern about volume of plant sources and possible collateral impact on food prices
      • biodiesel involves significant energy costs
    • potential benefits of biofuels produced through synthetic biology: possible reduction in global depends on fossil fuel, cuts in emissions, minimization of economic and political volatility surrounding fossil fuel reserves
      • synthetic biology aims to improve the speed and efficiency of converting biomass into advanced biofuels that are cleaner and more energy-efficient
      • synthetic biology also offers new biomass sources, or feedstocks, that are more efficient, reliable, low-cost, and scalable
      • large global reserves of hydrocarbons might be leveraged
    • butanol: a bioalcohol made by synthetic biology that is more promising that ethanol
    • photosynthetic algae engineered to secrete bio-oil continuously
      • biodegradable and harmless if spilled
      • less polluting and more efficient
      • consumes carbon dioxide
    • hydrogen fuel
  • health applications
    • research and development on this is still early
    • medicines
      • metabolic engineering: an organism’s metabolic pathways are redesigned to produce novel products or augment the production of current products (ie drugs)
      • can engineer molecules and cells that express proteins or pathways responsible for human disease
      • arteminsinin: antimalarial drug produced from genetically engineered e.coli that produces a high volume precursor that can be chemically converted to semi-synthetic artemisinin
    • vaccines
      • synthetic biology tools (ie DNA sequencing and computer modeling) may streamline production time of the flu vaccine
    • advancing biology and personalized medicine
      • cloning genes can be done in minutes
      • expansion of the DNA alphabet
      • makes individually tailored approaches to disease prevention and health care possible
      • custom protein and biological circuit design may enable delivery of smart proteins or programmed cells that self-assemble at disease sites
    • risks
      • release of engineered organisms to the wild
      • infectious diseases may be transmitted to lab workers or their family
      • novel organisms used to treat illness may trigger unanticipated adverse effects in patients
  • agricultural applications
    • potential benefits:
      • high-yield and disease-resistant plant feedstocks that can be supplemented with efficient and environmentally-friendly microorganisms to minimize water use and replace chemical fertilizers
      • nutritional benefits (ie boosting protein levels)
      • environmental biosensors that detect nutrient quality of soil or environmental degradation
      • biosurfactants could minimize pollution damage
    • potential risks:
      • uncontrolled environmental escape and disruption of ecosystems
      • new or stronger pests that are difficult to control
      • increased pesticide resistance and growth of invasic species

GMO basics

GMOs are living plants or microorganisms (ie, bacteria) that had their genetic code changed in some way

  1. a gene is inserted into the DNA of the nucleus of a single cell
  2. the cell is treated with plant hormones to stimulate growth and development
  3. the cell starts to divide
  4. the resulting cells become an entire plant

Why we use GMOs:

  • agriculture is vulnerable to 3 things: insects, weeds, and weather; most GMOs address the first two
    • insects: GMOs repel only the particular type of insect that feed on them
      • reduced the need for pesticides
    • weeds: GMOs developed to be resistant to herbicides
  • secondary benefits:
    • lower costs
    • less soil erosion (tillage isn’t as necessary for weed control)
    • less pesticides
  • GMOs also used to produce medicines and vaccines
    • before GMOs, medicine was extracted from blood donors, animal parts, or cadavers; had the risk of transmitted diseases, inconsistent quality, and unreliable supply
    • GMO medicines are more consistent and aren’t likely to be contaminated

GMOs and human health

  • A lot of attention on whether GMOs are safe to eat; currently there is no data that indicates any harm
    • over the two decades that GMOs have been on the market, there have been no health issues
  • GMOs have undergone more detailed evaluation than any other group of plants we consume
  • GMOs differ from a conventional plant by the addition of just one or two genes that produce one or two new proteins
    • the origins and functions of these proteins are well understood

GMOs and insects

  • pesticides are chemicals that will prevent pests from damaging plants, either by killing the insect or forming a toxic barrier around the plant
  • pesticides can kill beneficial organisms; they’re costly to farmers; they can be dangerous to animals and workers
    • GMOs solve this problem by modifying the plant’s protein manufacturing system to create one that is toxic to specific insects (their stomachs rupture)
  • GM crops don’t harm honeybees or butterflies

https://ag.purdue.edu/GMOs/Pages/The-Science-of-GMOs.aspx

GMOs: genetically-edited crops

Gene editing agriculture:

  • USDA regulations on GMOs apply only to those constructed using plant pathogens like bacteria, or their DNA; gene-edited plants are not regulated
  • Calyxt: startup that edits the genes of thousands of plants
    • scientists create designer plants that don’t have foreign DNA; adds or deletes snippets of genes—”accelerated breeding”
    • uses TALEN, co-developed by Calyxt founder, which was developed two years earlier than CRISPR, and as such has advanced further toward commercial crops
    • has designed 19 plants
      • edited soybeans to use in healthier oils (without trans fat)
        • will face competition with similar beans, ie a Monsanto GMO
      • including a wheat plant that grinds into a white flour with 3x more fiber
    • fast-to-market business model
  • obstacles:
    • easier to design and make DNA strands than to get them inside plants
    • uncertainty over which genes should be edited
      • Scientists know how oils are synthesized and why fruit turns brown, but genetic causes for other plant traits that are both well understood and easy to alter are unknown

GMOs

  • 90% of the soybean crop in the US are GMOs, genetically enhanced to be immune to Roundup
  • stigma: 40% of US adults think GMOs are less healthy
    • warring messages from scientists, agriculture lobbies, and NGOs like Greenpeace
  • legal in the US, Brazil, Argentina, and India, but banned throughout much of the rest of the world
  • unclear whether gene-edited crops are considered GMOs
    • no way to tell a gene-edited plant from a natural one
    • Lack of scrutiny of whether the plants could harm insects, spread their genetic enhancements to wild populations, or create superweeds
    • New Zealand and USDA’s organic council decided they are GMOs; the Netherlands and Sweden decided they weren’t; China and EU have yet to decide

https://www.technologyreview.com/s/609230/these-are-not-your-fathers-gmos/

GMOs

Two gene drive approaches:

  • replacement: alters a specific trait
  • suppression: suppresses a gene

CRISPR breaks DNA at a targeted location; the DNA heals itself in two ways:

  • nonhomologous end joining: two ends that were broken get stitched together in a random way
    • eventually confuses CRISPR, which is designed to locate a specific stretch of DNA
  • homology-directed repair: DNA uses a genetic template to heal

CRISPR potential:

  • could stop the spread of disease
  • could correct genes for inherited diseases or disabilities
  • could treat or prevent disease or disability
  • unlimited possibilities

CRISPR concerns:

  • no way to undo a gene drive once it is released in a wild population
  • uncertainty over how it may affect an ecosystem
  • population would likely develop a resistance to the gene drive
  • if carrier populations are edited to withstand diseases, the parasites may mutate
  • can damage DNA that is far from the target location
  • potential cell death after DNA editing
  • p53 protein could activate from stress from CRISPR activity and thwart it
  • some people may have already developed a resistance to CRISPR, which is a bacterial protein, during common bacterial infections
  • use for “enhancements” that could exacerbate social inequities