Gene Ecology versus Reductionism in Biology
Thomas Bøhn PhD Scientific Director, GenØk
This talk
• Human as beaver
• Two contrasting knowledge systems
• Organisms are composed of traits coded by genes
• Understanding organisms in their context
• Examples:
– Transgenic wheat – Transgenic maize – Transgenic soy
– Transgenic mosquitos
Beaver activities
- Cutting down a tree
- Flooding the environment - Ecosystem engineering
The human beaver
When we cut trees
When we build dams
When we engineer ecosystems
When we do agriculture
When we engineer organisms
• Large scale
– Single event GM Roundup ready soybean planted on
~60 mill ha
– 2 billion sterile insects per week in one factory
• Knowledge
- DNA sequences, genetics, laboratory, construction
• Knowledge gaps
– Contextual knowledge in receiving environment – Interactions in local food-webs
– Further spread and evolution
The Human as ecosystem engineer and beyond
• We change the external environment
– Transforming landscape into agriculture, cities, roads etc.
– Alter the environment through chemical pollution, global warming, introductions, etc.
• We change the organisms from within
– Breeding programs
– Genetic engineering/modern biotechnology
Genetic engineering
– using knowledge from the parts
Bacteria –
Bacillus thuringiensis
Bt-toxin (cry)gene –
’cut’
Virus - CaMV
CaMV-
promoter –
’cut’
AR
Plasmid vector –
”gene ferry”
Expression vector –
“ferry with insert”
CaMV + Bt –
’paste’
AR
„paste‟
AR
AR
A Bt-toxin producing maize cell
Cellwall Nucleus
Chromosomes Plasmids
Uncertainty:
- Insertion site - Copy number - Fragments
Gene gun
“Simple methods – complex results”
“Ferry with donor genes”
Introduced to:
• Recipient plant
• Ecosystem that interacts with this plant
• A dynamic agriculture
• Multiple cultural contexts
CaMV + Bt –
’paste’
AR
Donor genes - Gene ferry - Transgenic plant
Approach to agriculture
biotechnology and biosafety
• DNA causing…
• Traits causing…
• Plants or other organisms in order to:
– Remove disease – Remove pest insects – Remove weeds
– Remove parasite/viruses that carry human diseases
• Insertional effects/epigenetics
• Transgene x environmental interactions
• Unintended effects on health and environment
• Evolution of resistance
• Uncertainty
• Sustainable production
Gene Ecology
Reductionism
Example I: Transgene x environment interactions
– Transgenic fungus resistant wheat studied in glasshouse and in the field
– Four different events (same single gene/plant line) tested to see if unintended phenotypic effect could be traced
(From Zeller et al. 2010) vs
Glass house Field
Role of environmental context
(From Zeller et al. 2010)
Example II: Bt-transgenic maize
• Bt-toxin produced in all cells throughout the life- cycle (~60 mill hectares)
• Consumers of plant will be exposed to Bt-toxins
• Specific killing of pest insects
Grain 18%
Stover 29%
Unharvest- able 53%
(Wilts et al 2004)
Biomass:
• Development of tolerance in pest insect when
exposed to Bt- toxin
South Africa: evolutionary response in the pest insect
Buseola fusca
2004
2006
2004
2009
2010
Response in South Africa to response of resistance
• Spraying with pesticides
• Stacking of several Bt-toxins
• Wider non-target effects
• Possible long-term negative effects on ecosystem services
Example III: Herbicide tolerant GM plants – weed resistance
1. Herbicide use 2. Tolerant weeds 3. Increased use
4. Increased tolerance 5. Addition of other
chemicals (more toxic)
From Binimelis et al (2009)
Example IV: GM mosquitos
• Purpose: cut the life-cycle of parasitic disease carriers (protozoa, viruses, helminths)
• Main disease-carrying mosquito groups:
– Anopheles that transmit malaria
– Aedes that transmit yellow-, dengue-, Chikungunya- fever and West Nile virus
Example IV: How well do we understand GM mosquitos?
• “Considering the advances in both mosquito genomics and transgenesis, we are within reach of the creating an optimal genetically modified mosquito…”
• …However we lack:
– Laboratory colonies for important species – Logistics of field applications
– Knowledge on compatibilities between GM and wild type – Control over dispersion
– Risk assessment
– Community desire and political will to try new disease control practices
(From Terenius et al. 2008)
Conclusions
Two paradigms of knowledge meet in biosafety research
1. Product oriented engineering. Gene causes function.
Understanding based on DNA. Organism as collection of traits. Host of gene not relevant.
Environment less relevant. Secondary/system responses not in focus. Seed. Spray. Harvest.
2. Gene ecology. Genome-organism-environment interactions. Context matters. Context as cause:
– In gene expression patterns/function – In phenotype evolution, e.g. resistance – Greenhouse versus field, etc.
