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<h3 style="text-align: left;">Neuron culture</h3> | <h3 style="text-align: left;">Neuron culture</h3> | ||
− | <p> | + | <p><i>Imaging was performed in collaboration with the BioImagerie Photonique platform of the Institut Pasteur. Data are presented as MEAN ± SEM. Significance between 2 different groups was determined using an Ordinary one-way ANOVA test on the software Prism6 (GraphPad). (ns: non-significant, *: p<0.05, **: p<0.01, ***: p<0.001, ****: p<0.0001) </i> </p> |
− | + | <p>As an alternative to our recombinant proNGF for control experiments, we performed an in vitro neural primary culture with commercial NGF. For this, a pair of E18 Sprague Dawley cortexes were purchased from BrainBits.co.uk. We digested the tissue with manufacturer provided papain according to their protocol and seeded 40 000 dissociated neurons on our microfluidic chips with different conditions of culture for six days at 37°C, and 5% CO2. </p> | |
− | + | <p>On our two-chamber microfluidic devices, we seeded neurons only on one side. Fifteen chips were used in total. After six days, neurons are fixed with paraformaldehyde (PFA) 4% and stained with DAPI. For differentiated markers: MAP2 (coupled with Alexa Fluor 555), a cytoskeletal associated protein and Beta-III Tubulin (coupled with Alexa Fluor 488), one of the major components of microtubules and a neuron-specific marker were used.</p> | |
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+ | <p>We can see in Figure 11 that we had contaminations on many of our microfluidic chips, because we could not use antibiotic selection otherwise our bacteria would have suffered from it, and that most of our experiments could not be analyzed. However, no contaminations were apparent for eight of them. Two of these successful ones are displayed in Figure 12. </p> | ||
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− | <div class="legend"><b>Figure | + | <div class="legend"><b>Figure 11: </b> Bacteria found in our microfluidic device during cell culture (bacteria are in orange)</div> |
− | </div> | + | </div> |
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− | <div class="legend"><b>Figure | + | <div class="legend"><b>Figure 12: </b> Sprague Dawley E18 cortex neurons after six days of incubation at 37°C, and 5% CO2. Blue: DAPI stained nuclei, Green: Anti-Beta-III Tubulin coupled to Alexa Fluor 488, Yellow: Co-localization of anti-Beta-III Tubulin and MAP2. <b>(A)</b> Neurons were put in culture in Neurobasal, B27, GlutaMAX medium. <b>(B)</b> Neurons were put in culture in DMEM FBS 10% medium. </div> |
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− | <p>As we can see, we succeeded in growing the cells inside our device in presence of Neurobasal, B27 | + | <p>As we can see, we succeeded in growing the cells inside our device in the presence of Neurobasal, B27 and GlutaMAX medium. It is possible to see neurons passing through one chamber to the other in this experiment. Unfortunately, the PDMS of the microfluidic chips detached from the bottom of the glass culture dish, leading to the growth of cells not inside of the microchannel, but bellow them (Figure 13). </p> |
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<p>Neurons were put in culture in presence of commercial NGF at different concentration: 50 ng/mL, 250 ng/mL, 500 ng/mL, 750 ng/mL and 900 ng/mL. Optimal concentration was determined thanks to the modeling of NGF diffusion inside the medium. It was possible to capture the cells passing through one chamber of the microfluidic chip to other during a time lapsed using phase-contrast realized for the first 48h of culture at the Photometric BioImagery platform, proving that our device was working as expected. </p> | <p>Neurons were put in culture in presence of commercial NGF at different concentration: 50 ng/mL, 250 ng/mL, 500 ng/mL, 750 ng/mL and 900 ng/mL. Optimal concentration was determined thanks to the modeling of NGF diffusion inside the medium. It was possible to capture the cells passing through one chamber of the microfluidic chip to other during a time lapsed using phase-contrast realized for the first 48h of culture at the Photometric BioImagery platform, proving that our device was working as expected. </p> | ||
+ | <p>We also tested the action of commercial NGF on our culture. Neurons were put in culture in the presence of commercial NGF at different concentrations: 50 ng/mL, 250 ng/mL, 500 ng/mL, 750 ng/mL and 900 ng/mL. The optimal concentration was determined by modeling of NGF diffusion inside the medium. It was possible to capture the cells passing through one of the chambers of the microfluidic chip to the other side during a time-lapsed using phase-contrast microscopy recorded for the first 48h of culture at the <i>BioImagerie Photonique </i> platform, proving that our device was working as expected (Video 1).</p> | ||
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− | <div class="legend"><b> | + | <div class="legend"><b>Video 1: </b> A video excerpt of a 48h time-lapsed in phase contrast. Neuron entering the microchannel are visible. Medium of culture: Neurobasal, B27, GlutaMAX and commercial NGF at a concentration of 50 ng/mL. </div> |
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Revision as of 23:01, 17 October 2018
RECONNECT NERVES
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Summary
Achievements:
- Successfully cloned a biobrick coding for secretion of NGF in pET43.1a and iGEM plasmid backbone pSB1C3, creating a new part BBa_K2616000.
- Successfully sequenced BBa_K2616000 in pSB1C3 and sent to iGEM registry.
- Successfully co-transformed E. coli with plasmid secreting proNGF and plasmid expressing the secretion system, creating bacteria capable of secreting NGF in the medium.
- Successfully characterized production of proNGF thanks to mass spectrometry and western blot.
- Successfully observed axon growth in microfluidic chip in presence of commercial NGF.
- Successfully observed activity of our proNGF in invitro cellular culture compared to commercial NGF with a concentration between 500 ng/mL and 900 ng/mL.
Next steps:
- Purify secreted proNGF, and characterize its effects on neuron growth thanks to our microfluidic device.
- Global proof of concept in a microfluidic device containing neurons in one of the chamber, and our engineered bacteria in the other.
FIGHT INFECTIONS
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Summary
Achievements:
- Successfully cloned a biobrick coding for RIP secretion in pBR322 and in pSB1C3, creating a new part Bba_K2616001 .
- Successfully sequenced Bba_K2616001 in pSB1C3 and sent to iGEM registry.
- Successfully cultivated S. aureus biofilms in 96-well plates with different supernatants. Although there was a high variability in our results, and we used several protocols to overcome it, in one case, we were able to observe a reduction in biofilm formation in the presence of our RIP.
Next steps:
- Clone the sensor device with inducible RIP production upon S. aureus detection.
- Improve the characterization of RIP effect on biofilm formation with a more standardized assay.
KILL SWITCH
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Summary
Achievements:
- Successfully cloned the biobrick Bba_K2616002 coding for toxin/antitoxin (CcdB/CcdA) system in pSB1C3, creating a new part.
- Successfully sequenced BBa_K2616002 in pSB1C3 and sent it to iGEM registry.
- Successfully observed normal growth of our engineered bacteria at 25°C and 37°C and absence of growth at 18°C and 20°C, showing the efficiency of the kill switch.
Next steps:
- Find a system that kills bacteria when released in the environment rather than just stopping their growth.