168 - Moeseneder-Everson-Jones - Presentation.ppt
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Transcript of 168 - Moeseneder-Everson-Jones - Presentation.ppt
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BiofuelsMethods of modification of
algal DNA for increasing synthetic bio-fuel production
Chris MoesenederBronte Everson
Dylan Jones
Biofuels from algae seem to be a promising alternate energy source
Not economically viable compared to current fossil fuel industry
Scientists are attempting to increase economic viability by modifying algal genomes to increase lipid production
(Georgianna et al., 2012)
Biofuels from algae
2Georgianna, D.R. et al., 2012. Nature, 488: 329-335
Increasing permeability of cell membranes to allow DNA
constructs to be integrated into the cell
Manipulation of DNA and multiple loci sites during
recombination
Utilising the natural power of photosynthesis for energy
production
Biologicalconcepts
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Through electroporation, the Nannochloropsis sp. cells in a high electric field, the cell wall can be penetrated in order for DNA fragments to be
integrated into the original DNA
The chloroplast genome of Chlamydomonas reinhardtii was altered in order to better utilise
the power of photosynthesis
Methods of DNA modification to improve lipid production in microalgae can have complex and
sometimes do not produce feasible results
Key points
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Aim was to find a system for the cloning and modification of the chloroplast genome in Chlamydomonas reinhardtii
(O’Neill et al., 2011)
Genetic manipulation of the algal species was limited due to the lack of homologous recombination and a heavily
annotated genome nuclear sequence (O’Neill et al., 2011)
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An exogenous chloroplast genome for complex sequence manipulation in algae – O’Neill et al. (2011)
An exogenous chloroplast genome for complex sequence manipulation in algae – O’Neill et al. (2011)
O'Neill et al., 2011, Nucleic Acids Research, 40: 2782-2792
!
Aimed to develop an efficient transformation method for Nannochloropsis sp. (Killian et al., 2011).
Electroporation of the Nannochloropsis sp. cells allowed DNA transformants to penetrate the cell wall (Killian et al., 2011)
Gene knockout constructs used to test for homologous recombination, with nitrite reductase (NiR) and nitrate reductase (NR) genes targeted
Disruption of these genes can be detected as the alga is known to grow on nitrate and nitrite based sources (Killian et al., 2011)
High-efficiency homologous recombination in the oil-producing alga Nannochloropsis sp.- Killian et al. (2011)High-efficiency homologous recombination in the oil-producing alga Nannochloropsis sp.- Killian et al. (2011)
Killian et al., Proc. Natl Acad. Sci. USA, 108: 21265-21269 6From Killian et al., 2011
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O’Neill et al. (2011) Findings
From O’Neill et al., 2011
Exogenous modification was possible through the combination
of algal DNA sequences and bacterial selection markers. DNA
sections were amplified using PCR in order for the modification of
algal DNA to occur (O’Neill et al., 2011)
The modified algal DNA could then be assembled in a yeast hybrid
and transplanted back into algal cells
Linear amount of DNA used in electroporation relative to the amount transformants obtained. Shows that more DNA fragments are needed for efficient transformation (Killian et
al., 2011)
Successful gene knockout of NR / NiR in one transformation step ( 94%) discovered that Nannochloropsis is haploid
(Killian et al., 2011, Table 2)
Haploid nature allows for easy insertion of transformants through homologous recombination
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Killian et al. (2011) Findings
From Killian et al., 2011
Both research groups pursued a similar goal, but using very different methods
Killian et al. (2011): a simple method, but had no suggestions for applications
O’Neill et al. (2011): a very complex methodology, but showed that it could be used for sequence deletions, rearrangement and
minimization
Neither of the studies clearly show how their findings will lead to an increase in oil production
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Judgement and Evalution
Ways of economically producing biofuels from algae are important
However, these research papers don’t shed light on non- CO2
emitting alternative energy sources.
The concentration of specific model algal species and strains for biofuel production will cause a reduction in the variability of the
gene pool, hence leading to a lack of disease resistance
All images were purchased from iStockPhoto for this presentation 10