Download What has changed - Center for Genetics and Society

What has changed ?
Ricarda A. Steinbrecher, Ph.D.
EcoNexus, Oxford, UK – www.econexus.info
CGS webinar 14 April 2016
[email protected]
What has changed?
1) increased ability to make deeper and more complex
changes in the genetic makeup and metabolic pathways
of living organisms.
2) targeting special DNA sequences (‘precision’)
 gene editing (‘site specific nucleases’)
3) Population-scale genetically engineering
 gene drives
New Genetic Engineering
Techniques (NGETs)
1) Genome editing techniques
esp. CRISPR/Cas
2) various current/traditional GE techniques:
a) re source of DNA (cisgenics & intragenics)
b) no intended GM sequence in end product
3) Genetic Engineering techniques that alter the ‘outside’
of the DNA, thus changing gene regulation.
(ie gene silencing with RNA dependent DNA Methylation (RdDM)
 Epigenetic changes
Source: R.Steinbrecher, EcoNexus
cells
nucleus
chromosome
DNA
gene
A
A
C
T
C
G
T
Basepairs: A-T & C-G (nucleotides)
T
T
G
A
G
C
A
Transformation
?
Agrobacterium
used as “shuttle”
No control of where the gene will insert itself:
• Random integration
• Imprecision (incl. superfluous DNA)
• 100 -1000s of Mutations (Sala et al. 2000, Wang et al. 1996, Labra et al 2001)
Wilson AK, Latham JR and Steinbrecher RA. Transformation-induced Mutations in Transgenic Plants.
Biotechnology and Genetic Engineering Reviews, Vol 23, December 2006, pp. 209-237
Source: R.Steinbrecher, EcoNexus
Particle
bombardment
So what is the answer?
• you design molecular scissors to go and
cut the DNA at a place you want.
• either to: insert a gene, delete a sequence
or simply change a sequence
= precision??? = predictability? = safe??
Design/choose
special cutting
enzyme:
CRISPR/Cas9
determine sequence of target DNA
mutation, deletion, insertion of gene
repair cut
Unpredictabilities and Risks
Off-target effects (mutations in the genome)
a) changes of function of proteins (if in coding sequence)
b) changes in the expression of genes, eg resulting in:
increased presence of plant toxins, absence of
proteins important for nutrition, plant defence or
disease resistance, increased presence of allergens.
Unintended integration of added DNA into the genome
Impacts of the genetic engineering processes, here due to
the “delivery” of the
Steinbrecher, R (2015). Genetic Engineering in Plants and the “New Breeding
Techniques” (NBTs) - Inherent risks and the need to regulate. www.econexus.info
ct: glycolysis - glucose oxidation in order to obtain ATP
cb: citiric acid cycle (Kreb’s cycle) acetyl-CoA oxidation in order to obtain GTP & valuable intermediates.
http://homepage.ufp.pt/pedros/bq/integration.htm
bl: AA degradation
The idea of Precision
The idea of precision is based on that one knows
what one is doing – here this is not the case.
What is missing is the contextualisation into
• the genome
• the epigenetic landscape
• the organism
• the ecosystems
• the socio-economic conditions that differ around the world
Precision around nucleotides gives a false sense of
predictability and safety – there is no data to support such
extrapolations.
Source: R.Steinbrecher, EcoNexus
Knowledge & precision at the level of nucleotides is only the
bottom layer.
Gene Drives
- Population-scale genetic engineering
- Ecosystem engineering
what?
-crops & weeds
-pests and ‘invasive’ species
-carriers, pathogens
-any organism
Source: http://wyss.harvard.edu/staticfiles/newsroom/pressreleases/Gene drives FAQ FINAL.pdf
Source: http://wyss.harvard.edu/staticfiles/newsroom/pressreleases/Gene drives FAQ FINAL.pdf
Concerns & Risks
• impacts on biodiversity
• impacts on humans, environment, food security
• impacts on local & global ecosystems
• …. in the wrong hands ….