Team:Dundee/Notebook/normal

From 2014.igem.org

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<h3>Week 0</h3>  
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A few members of the team, fresh from their exams, began the initial literature reviews necessary to identify the genes and promoters that were required in our biological sensors that would detect and respond to signaling molecules released by <i>Stenotrophomonas maltophilia</i> (DSF), <i>Burkholderia cenocepacia</i> (BDSF) and <i>Pseudomonas aeruginosa</i> (PQS). Finally, <i>rpfC</i>, <i>rpfG</i>, <i>clp</i> and P<i><sub>manA</sub></i> were to be cloned to detect DSF; <i>BCAM0227</i>, <i>BCAM0228</i> and P<i><sub>cbld</sub></i> for BDSF; and <i>pqsR</i> and P<i><sub>pqsA</sub></i> for PQS.
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Primers were designed (which included restriction sites required for cloning and also HA-tags to detect for protein expression) for the PQS sensing system and ordered from Sigma Aldrich.
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A few members of the team, fresh from their exams, began the initial literature reviews necessary to identify the genes and promoters we would need to clone in order to detect and respond to the signaling molecules DSF (from <i>Stenotrophomonas maltophilia</i>), BDSF (from <i>Burkholderia cenocepacia</i>) and PQS (from <i>Pseudomonas aeruginosa</i>). Finally, <i>rpfC</i>, <i>rpfG</i>, <i>clp</i> and P<i>manA</i> were selected to deal with DSF; <i>BCAM0227</i>, <i>BCAM0228</i> and P<i>cbld</i> for BDSF; and <i>pqsR</i> and P<i>pqsA</i> for PQS. Primers (including restriction sites for cloning and tags to detect protein expression) were designed for the smallest system – PQS - and ordered from Sigma Aldrich.<br/>
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All sequences were analyzed with Webcutter 2.0 to detect restriction sites that conflict with the BioBrick assembly standard RFC [10]. It was found <i>clp</i> contained an illegal <i>Pst</i>I site; <i>BCAM0228</i> and <i>rpfg</i> contained an illegal <i>Eco</i>RI site. Primers were then designed for use with QuikChange™ Site-Directed Mutagenesis Kit to remove illegal sites. It was decided at this stage that for the DSF system, homologues of all sequences would be taken from <i>Xanthomonas campestris</i> pv. <i>campestris</i> as they have identical functions but contain fewer illegal restriction sites.<br/>
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All sequences were analyzed with Webcutter 2.0 to detect restriction sites that conflict with the BioBrick assembly standard RFC [10] and primers were designed for use with QuikChange™ Site-Directed Mutagenesis Kit to remove illegal sites. It was decided at this stage that for the DSF system, homologues of all sequences would be taken from <i>Xanthomonas campestris pv. campestris</i> would be used as they have identical functions but contain fewer illegal restriction sites.
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However, <i>BCAM0227</i> was proving problematic. It was so large (3000+bp), and had so many illegal restriction sites, it would have taken the full ten weeks to QuikChange™  them out! We decided to send it for synthetic sequencing by Dundee Cell Products in two separate parts. We hoped this would allow us to successfully ligate the two pieces together into one without mistakes.<br/>
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<h3>Week 1</h3>  
<h3>Week 1</h3>  
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The team are all together! Work begins…<br/>
The team are all together! Work begins…<br/>
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We began organizing our raw materials, setting up overnight cultures of our vectors (pSB1C3 for BioBricks, and our supervisor’s own pUniprom for experiments) and obtaining gDNA from <i>P. aeruginosa</i>, <i>X. campestris</i> and <i>B. cenocepacia</i> from generous lab members.
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We began organizing our raw materials, setting up overnight cultures of our vectors (pSB1C3 for BioBricks, and our supervisor’s own pUniprom for experiments) and obtaining gDNA from <i>P. aeruginosa</i>, <i>X. campestris</i> and <i>B. cenocepacia</i> from Drs Robert Ryan and Shi-Qi An from the Division of Molecular Microbiology in the College of Life sciences at the University of Dundee
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By the end of the week we had cloned <i>pqsR</i> and P<i>pqsA</i> into pSB1C3, phew!<br/>
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By the end of the week we had cloned <i>pqsR</i> and P<i><sub>pqsA</sub></i> into pSB1C3, phew!<br/>
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As for the dry-lab, the first week consisted mostly of reading papers and harassing Gillian, our mathematical biologist, for definitions of all the bio-jargon. In fact, most of our early discussions about modelling our systems consisted of furrowed brows from both sides and questions such as “a differential what?” and “Uhhh, transcriptional whatnot?”  
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As for the dry-lab, the first week consisted mostly of reading papers and harassing Gillian, our mathematical biologist, for definitions of all the bio-jargon. In fact, most of our early discussions about modelling our systems consisted of furrowed brows from both sides, and questions such as “a differential what?” and “Uhhh, transcriptional whatnow?”  
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<img class="centered img-responsive" src="https://static.igem.org/mediawiki/2014/7/71/Week2Dun.png"/>
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In order to test our systems we decided to clone them into pUniprom, a high copy-number plasmid with a large and varied multiple cloning site downstream of a strong, constitutive promoter: P<i>tat</i>.  In order to arrange our sequences in such a way that there would be no leakage of our reporter (see above), we had to employ a bit of cloning trickery by inserting our sensing and responding fragments in opposite orientations. This involved cloning them into separate fragments and then flipping them round into pUniprom. To the bench! <br/>  
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In order to test our biological sensors we decided to clone them into pUniprom, a high copy-number plasmid which has a large and varied multiple cloning site downstream of a strong, constitutive promoter: P<i><sub>tat</sub></i>.  In order to arrange our sequences in such a way that there would be no leakage of our reporter, we had to employ a bit of cloning trickery by inserting our sensing and responding fragments in opposite orientations. This involved cloning them into separate fragments and then flipping them round into pUniprom. And so to the bench we went! <br/>  
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Now that the plan for the plasmid was in place, we began to enter all the information onto Netlogo to model how the system would behave in the presence of different concentrations of PQS.
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Now that the plan for the plasmid was in place, we began to enter all the information onto Netlogo to model how the system would behave in the presence of different concentrations of exogenous PQS.  
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<h3>Week 3</h3>
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While members of the team continued to work on building the PQS sensor, we also got started on planning and constructing the DSF sensor. From this point onwards we decided to use GFP rather than mCherry, as we already had antibodies against it for blotting later. Our desired DSF sensor has four sensory components! This posed a bit of a problem for cloning, as we thought we would need to use more restriction enzymes than we had access to. The solution? Order primers that include a 5’ <i>Bgl</i>II site and 3’ <i>Bam</i>HI-<i>Xba</i>I sites. This way, fragments could be cloned in sequentially. Each new insert could be cut with <i>Bgl</i>II-<i>Xba</i>I, and the ever-growing vector cut with <i>Bam</i>HI-<i>Xba</i>I. This is because the <i>Bgl</i>II and <i>Bam</i>HI overhangs are complementary, but upon ligation leave a scar that is not recognized by either enzyme (see below). The 3’ <i>Bam</i>HI-<i>Xba</i>I site allows this process to be repeated indefinitely. Woo, idempotency! A lot of cloning followed...
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Time to start on the DSF system. We decided to use GFP rather than mCherry from this point onwards as we already have antibodies against it for blotting later. Because the DSF system acts via a reduction in cellular levels of the 2nd messenger c-di-GMP, we thought it best to include a diguanylate cyclase, YdeH, in the system to replenish this important molecule afterwards. So now the DSF system has four sensory components! This posed a bit of a problem for cloning as we thought we would need to use more restriction enzymes than we had access to. The solution? Order primers that include a 5’ <i>Bgl</i>II site and 3’ <i>Bam</i>HI-<i>Xba</i>I sites. This way, fragments can be cloned in sequentially with each new insert cut with <i>Bgl</i>II-<i>Xba</i>I and the ever-growing vector cut with <i>Bam</i>HI-<i>Xba</i>I as the <i>Bgl</i>II and <i>Bam</i>HI overhangs are complementary but upon ligation leave a scar that is not recognized by either enzyme (see below). The 3’ <i>Bam</i>HI-<i>Xba</i>I site allows this process to be repeated indefinitely. Woo, idempotency!  
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<h3>Week 4</h3>  
<h3>Week 4</h3>  
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A week of sequencing… We have a sequencing service downstairs from the lab who kindly gave us 100 free sequencing runs (which we quickly exceeded!) so after every cloning step we sent a sample to be sequenced – the results were a source of merriment and heartbreak in equal measure…it turned out that our 1st clone (PQS system from week 1) wasn’t quite right. So began Dimitrios’ epic journey into the world of BioBricks!<br/>
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We also began the lengthy task of removing all the illegal restriction sites from the fragments bound for BioBricking.
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So it turned out that, after a bit more sifting through papers, the Netlogo model for PQS was not quite right. While we figured that out we began to calculate the ordinary differential equations for the same system.
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With lots of cloning, comes lots of sequencing… which was all kindly carried out by the sequencing service downstairs from our lab. To help us along the way Professor Philip Cohen kindly granted us 100 free sequencing runs (which we quickly exceeded!). After every cloning step for building our PQS and DSF sensor, we sent a sample to be sequenced – the results were a source of merriment and heartbreak in equal measure…it turned out that our cloned PQS sensor wasn’t quite right so we spent the week trying to rectify this. <br/>
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We also began the lengthy task of removing all the illegal restriction sites from the fragments bound for BioBricking; and so began Dimitrios’ epic journey into the world of BioBricks!<br/>
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It turned out, (after a bit more sifting through papers), that the Netlogo model for PQS was not quite right. While we figured that out, we began to calculate the ordinary differential equations for the same system.
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<h3>Week 5</h3>  
<h3>Week 5</h3>  
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It turned out that our very first transformations of YdeH into <i>E. coli</i> JM110 didn’t seem to be working. Nothing we did was different from any other transformations so we wondered if YdeH is toxic to the cells - maybe too much c-di-GMP is a bad thing!
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We decided to try cloning it under an inducible promoter…later! The DSF model was slightly harder to work with than PQS as it contained a lot of components and our first model started with about 12 equations! We were able to reduce these down and simplify the model, which enabled us to input them into MATLAB and produce some graphs. We had a few problems determining exactly what our GFP production was reliant on, but after a lot of work on our blackboard, we came to a conclusion. Again, our deterministic model allowed us to change our initial conditions allowing us to see what would happen.<br/>
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PqsR and P<i>pqsA</i> were successfully BioBricked!<br/>
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A lot of stochastic modelling going on this week, PQS wild type and PQS <i>E.coli</i> being our priority. Adding in an external signal is proving a little difficult as we’re not getting our expected results! A lot of trial and error in trying to match up parameters from MatLab and Maple, but we think we’re there! Netlogo is also coming along nicely, with PQS wild type and PQS <i>E. coli</i> finished! BDSF <i>E. coli</i> is almost finished too, so after that only DSF to tackle!
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We successfully biobricked P<i><sub>pqsA</sub></i>!<br/>
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Thankfully we had succesfully ligated P<sub><i>pqsA</sub></i> with <i>pqsR-HA</i> into pUniprom.
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After western blotting the PQS system, we obtained results which showed that PqsR was being expressed. We then obtained synthetic PQS from Sigma Aldrich to test this sensor for the production of GFP.
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Meanwhile...the dry team were finding the the DSF model slightly harder to work with than PQS (sorry guys!), as it contained a lot of components; our first model started with about 12 equations! We were able to reduce these down and simplify the model, which enabled us to input them into MATLAB and produce some graphs. We had a few problems determining exactly what our GFP production was reliant on, but after a lot of work on our blackboard, we came to a conclusion! Again, our deterministic model allowed us to change our initial conditions allowing us to see what would happen.<br/>
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A lot of stochastic modelling happened during this week; PQS wild type and PQS <i>E.coli</i> being our priority. Adding in an external signal proved a little difficult, as we did not get the expected results! There was a lot of trial and error in trying to match up parameters from MatLab and Maple, but by the end of the week we thought we were there! Netlogo was also coming along nicely, with PQS wild type and PQS <i>E. coli</i> finished! BDSF <i>E. coli</i> was almost finished too, with only DSF to tackle after that!
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<h3>Week 6</h3>  
<h3>Week 6</h3>  
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<img class="centered img-responsive" src="https://static.igem.org/mediawiki/2014/9/91/Week6Dun.png"/>
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We successfully removed the first illegal site from RpfC after analysing sequencing results. Meanwhile <i>clp</i> BioBricking was underway and work had begun on the BDSF system…halfway through the 10 weeks and we were feeling productive (if showing the first signs of frazzling)! The dry lab were certainly ahead of the game as far as BDSF was concerned; after working through the mammoth DSF system, the closely related two-component BCAM0227/BCAM0228 system was a breeze. In fact, with such a head-start it was decided that there would be a presentation given by the maths boffins of the team entitled: “Modelling for the Perplexed Biologists and Dave”. This was an interactive lesson on how to apply equations to biological systems which helped the lab-rats get to grips with how the figures being generated by the dry team could inform the final design of the biological systems.<br/>
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Around this time, the “Device Committee” was formed; a small group of wet and dry members who would begin the design of a physical unit to house and interpret the output from our engineered bacteria. This began with background reading on creating a GFP-fluorescence reading device. Order initial parts to build a light sensing device based on LED light source so we could modulate the light levels. We considered that we would have to use MatLab to carry out calculations. Our visits to the clinic took a more direct focus, and we started interviewing patients, not just about living with CF, but about the design of the physical detector.
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RpfG, RpfC and Clp cloned into pUniprom!
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We were all excited to test our first sensor, an inducible GFP production assay was set up, by spiking overnight cultures of transformed <i>E. coli</i> MC1061 with a range of concentrations of synthetic PQS. Unfortunately, we obtained no mCherry expression....along with a lot of perplexed biologists!
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We successfully removed the first illegal site from <i>rpfC</i>. Meanwhile <i>clp</i> BioBricking was underway, and work had begun on the BDSF system.
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We were halfway through the 10 weeks and we were feeling productive! The dry lab were certainly ahead of the game as far as BDSF was concerned; after working through the mammoth DSF system, the closely related two-component BCAM0227/BCAM0228 system was a breeze. In fact, with such a head-start it was decided that there would be a presentation given by the maths boffins of the team entitled: “Modelling for the Perplexed Biologists and Dave”. This was an interactive lesson on how to apply equations to biological systems which helped the lab-rats get to grips with how the figures being generated by the dry team could inform the final design of the biological systems. By the end of the week, <i>rpfG</i>, <i>rpfC</i> and <i>clp</i> were cloned into pUniprom!<br/>
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Around this time, the “Device Committee” was formed; a small group of wet and dry members who would begin the design of a physical unit to house and interpret the output from our engineered bacteria.  This began with background reading on creating a GFP-fluorescence reading device. Order initial parts to build a light sensing device based on LED light source so we could modulate the light levels. We considered that we would have to use MatLab to carry out calculations. Our visits to the clinic took a more direct focus, and during the interviews we were conducting each week, we started asking patients for their thoughts on the design of the physical detector.
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<h3>Week 7</h3>  
<h3>Week 7</h3>  
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<img class="centered img-responsive" src="https://static.igem.org/mediawiki/2014/a/a6/Week9Dun.png"/>
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Initial experiments with a photodiode, Arduino and a green LED for the physical device. First designs showed us that we would need an excitation source to induce fluorescence, this would necessitate the inclusion of filters and amplifiers…extremely complicated! Discussions were had with the entire team about eventually using firefly luciferase as a reporter in the place of fluorescent proteins. <br/>
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BCAM0227 successfully cloned into pUniprom and <i>clp</i> BioBricked! However, sequencing results for RpfG QuikChange showed that it was actually RpfC…oops! <br/>
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All promoters had now been successfully cloned and sequenced, so were cloned along with their fluorescent reporters into pUniprom.<br/>
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Repeated the RpfG QuikChange.<br/>
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Sequencing results for <i>rpfG</i> QuikChange™  showed that it was actually <i>rpfC</i>…oops! Steps were made to rectify this quickly!<br/>
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All promoters had now been successfully cloned and sequenced and so the job now was to clone them along with their fluorescent reporters into pUniprom.
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Our two sequences of <i>BCAM0227</i> were successfully returned from the sequencing company, Dundee Cell Products, for us to work with. The two separate sequences were digested, and work commenced to try and ligate them together into pbluescript...easier said than done!<br/>
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Initial experiments with a photodiode, Arduino and a green LED for the physical device, commenced. First designs showed us that we would need an excitation source to induce fluorescence, this would necessitate the inclusion of filters and amplifiers…extremely complicated! Discussions were had with the entire team about eventually using firefly luciferase as a reporter in the place of fluorescent proteins. <br/>
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<h3>Week 8</h3>  
<h3>Week 8</h3>  
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Good catch by a studious member of the dry lab – it turned out that <i>B. cenocepacia</i> produces a signaling molecule called HHQ which is so similar to PQS that it can bind to PqsR and activate the system! After some modelling, the decision was made to re-design the <i>P. aeruginosa</i> system to detect <i>Pseudomonas</i> autoinducer 1 (PAI-1). Lots of work for the wet team!<br/>
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BioBricking of RpfG commences upon receiving good sequencing results.<br/>
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DSF system looked like it was ready for testing with our newly acquired synthetic DSF (minus YdeH – this is still killing our cells). A culture of <i>E. coli</i> MC1061 transformed with the DSF plasmid is set up for blotting alas, RpfC-HA is not being expressed! Back to the cloning board…
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After lots of modelling of the PQS system, and trying to troubleshoot why our system was not expressing mCherry, the decision was made to design another two biological sensors for <i>P. aeruginosa</i>, which would detect another quorums sensing molecule <i>Pseudomonas</i> autoinducer 1 (PAI-1). Lots of work for the wet team!<br/>
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An overnight culture of <i>E. coli</i> MC1061 transformed with the DSF plasmid was pelleted and prepared for western blotting for detection of our proteins - alas, RpfC-HA is not being expressed! Back to the cloning board…
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BioBricking of <i>rpfG</i> was undertaken upon receiving good news from sequencing that our illegal <i>Eco</i>RI restriction site had been removed.<br/>
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<h3>Week 9</h3>  
<h3>Week 9</h3>  
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The Device Committee met up with Dr. Stephen Reynolds from the University’s physics department who helped us to optimize our light-detecting circuit. Constructed a crude (but effective) Faraday cage from aluminium foil and a cardboard box to eliminate electrical interference from the buzzing computers in the dry lab…<br/>
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RpfC was, at great length, cloned into pUniprom along with the rest of the DSF system, time for some tests!<br/>
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BCAM0227 was cloned from <i>X. campestris</i> DNA and sent for sequencing with good results first time! It was then swiftly cloned into pUniprom (already containing the P<sub>cbld</sub>-<i>gfp</i> fusion).<br/>
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BCAM0228 QuikChange was complete and sent for sequencing.<br/>
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The tricksome <i>BCAM0227</i> was successfully ligated together into one gargantuan sequence, and swiftly cloned into pUniprom (already containing the P<sub><i>cbld</i></sub>-<i>gfp</i> fusion).<br/>
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BCAM0228 QuikChange of the illegal <i>Eco</i>RI site was complete and sent for sequencing to confirm this was actually the case.
 +
The Device Committee met up with Dr. Stephen Reynolds from the University’s physics department, who helped us to optimize our light-detecting circuit. We constructed a crude (but effective!) Faraday cage from aluminium foil and a cardboard box to eliminate electrical interference from the buzzing computers in the dry lab…<br/>
 +
We managed to clone <i>rpfC</i> into pUniprom, along with the rest of the DSF system; time for some tests!<br/>
</p>           
</p>           
-
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<hr>
<hr>
<h3>Week 10</h3>  
<h3>Week 10</h3>  
-
<br/>
+
<div class="col-xs-3">
-
<br/>
+
<img class="centered img-responsive" src="https://static.igem.org/mediawiki/2014/3/32/Week10Dun.png"/>
-
We obtained a culture of <i>Vibrio fischeri</i> from Dr Sarah Coulthurst’s lab and began streaking plates to test out our physical device for detection of the bioluminescence from <i>V. fischeri</i> luciferase – it worked! Although, at this point our device was essentially half of a water bottle covered in insulating tape, an Arduino and a voltage meter. However, we had come up with a product name: the Light Amplifying Signal Sensing Object, because every good cowboy needs a L.A.S.S.O., right? Time for a more robust design, maybe 3D printed… iGEM alumnus and polymath Nasir Ahmad showed us how to draw up plans using Google Sketch.
+
-
BCAM0228 sequence came back looking good, into pUniprom and pSB1C3 it went!
+
-
</p>        
+
</div>
</div>
-
<div class="col-sm-3 col-xs-3 col-md-3">
+
<div class="col-sm-9 col-xs-9 col-md-9">
 +
<p>
 +
Sequencing results came back for the QuikChanged <i>BCAM0227</i> and confirmed that the <i>Eco</i>RI site had been removed and so we handed it over to Dimitrios to clone it into pSB1C3.We obtained a culture of <i>Vibrio fischeri</i> from Dr Sarah Coulthurst’s lab, and began streaking plates to test out our physical device for detection of the bioluminescence from <i>V. fischeri</i> luciferase – it worked! At this point our device was essentially half of a water bottle covered in insulating tape, an Arduino and a voltage meter...However, we had come up with a product name: the Light Amplifying Signal Sensing Object, because every good cowboy needs a L.A.S.S.O., right?! It was time for a more robust design; our thoughts moved to 3D printing, and iGEM alumnus and polymath Nasir Ahmad showed us how to draw up plans using Google Sketch.
 +
</p>         
</div>
</div>
</div>
</div>
<div class="row">
<div class="row">
-
<div class=""col-sm-9 col-xs-9 col-md-9">
 
-
<p>
 
<hr>
<hr>
<h3>Week 11</h3>  
<h3>Week 11</h3>  
-
<br/>
+
<div class="col-xs-3">
-
<br/>
+
<img class="centered img-responsive" src="https://static.igem.org/mediawiki/2014/1/10/Week11Dun.png"/>
-
At this stage, we had all of our systems (barring PAI-1) cloned into pUniprom and ready for blotting. So with a little (actually, rather a lot) of help from master-blotter Prof Frank Sargent, we set to the task with all the elation of a team that can see the end of cloning in sight.<br/>
+
-
The Device Committee met with Dr. Mike MacDonald from the Institute for Medical Science and Technology (IMSAT) to discuss plans for building a device and learned from him the importance of following international standards of operation (ISOs). From this point on we endeavoured to follow ISOs 13485 (medical devices) & 9001(general quality management) so that, if the device were to be taken on by a company, our design and parts would be easily replicable.<br/>
+
-
Some of the wet team set to the noble task of cloning our replacement <i>Pseudomonas</i> system. Luckily, all the components we needed were included in the 2014 iGEM distribution pack so we stabbed, rehydrated and got to work.<br/>
+
-
We decided to use the P<i>tet</i> BioBrick as a vector and cloned in <i>lasR</i> downstream.<br/>
+
-
YdeH was successfully BioBricked – another one bites the dust!<br/>
+
-
</p>        
+
</div>
</div>
-
<div class="col-sm-3 col-xs-3 col-md-3">
+
<div class="col-sm-9 col-xs-9 col-md-9">
 +
<p>
 +
At this stage, we had all of our systems (barring PAI-1) cloned into pUniprom and ready for blotting. So with a little, (actually, rather a lot), of help from "The Blotfather" Prof. Frank Sargent, we set to the task with all the elation of a team that can see the end of cloning in sight.<br/>
 +
Meanwhile, some of the wet team set to the noble task of cloning our replacement <i>Pseudomonas</i> system. Luckily, all the components we needed were included in the 2014 iGEM distribution pack so we stabbed, rehydrated and got to work. We started by using the P<i><sub>tet</sub></i> BioBrick as a vector and cloned in <i>lasR</i> downstream.<br/>
 +
The Device Committee met with Dr. Mike MacDonald from the Institute for Medical Science and Technology (IMSAT) to discuss plans for building a physical device. They learned from him the importance of following international standards of operation (ISOs). From this point on we endeavoured to follow ISOs 13485 (medical devices) & 9001(general quality management) so that, if the device were to be taken on by a company, our design and parts would be easily replicable.<br/>
 +
 
 +
 +
 +
 +
</p>         
</div>
</div>
</div>
</div>
<div class="row">
<div class="row">
-
<div class=""col-sm-9 col-xs-9 col-md-9">
 
-
<p>
 
<hr>
<hr>
<h3>Week 12</h3>  
<h3>Week 12</h3>  
-
<br/>
+
<div class="col-xs-3">
-
<br/>
+
<img class="centered img-responsive" src="https://static.igem.org/mediawiki/2014/2/24/Week12Dun.png"/>
-
The BDSF system, after a successful western blot to check for protein expression, was set up for an inducible GFP production assay by spiking overnight cultures of transformed <i>E. coli</i> MC1061 with a range of concentrations of synthetic BDSF. Unfortunately, GFP appeared to be expressed at all concentrations, including 0 µM! This experiment clearly needed to be repeated.
+
-
The Device Committee were having a great time designing the L.A.S.S.O.; a cavity here, a plunger there, maybe some springs... They started looking into ISO requirements as specified by Dr MacDonald.<br/>
+
-
</p>        
+
</div>
</div>
-
<div class="col-sm-3 col-xs-3 col-md-3">
+
<div class="col-sm-9 col-xs-9 col-md-9">
 +
<p>
 +
After western blotting the BDSF system, we obtained results which showed that both BCAM0227 and BCAM0228 were both being expressed. We then set up for an inducible GFP production assay, by spiking overnight cultures of transformed <i>E. coli</i> MC1061 with a range of concentrations of synthetic BDSF. Unfortunately, GFP appeared to be expressed at all concentrations, including 0 µM! This experiment clearly needed to be repeated...
 +
The cloning of the two PAI-1 sensors was continued, by ligating two different promoters downstream of LasR; P<i><sub>lasb</sub></i> and P<i></sub>luxR</i></sub>.
 +
The Device Committee were having a great time designing the L.A.S.S.O.; a cavity here, a plunger there, maybe some springs... taking into account the ISO requirements as specified by Dr MacDonald.<br/>
 +
</p>         
</div>
</div>
</div>
</div>
<div class="row">
<div class="row">
-
<div class=""col-sm-9 col-xs-9 col-md-9">
 
-
<p>
 
<hr>
<hr>
<h3>Week 13</h3>  
<h3>Week 13</h3>  
-
<br/>
+
<div class="col-xs-3">
-
<br/>
+
<img class="centered img-responsive" src="https://static.igem.org/mediawiki/2014/3/38/Week13Dun.png"/>
-
The dry team set about modelling what potential savings could be made from the implementation of The Lung Ranger/L.A.S.S.O. by investigating the cost to the NHS of keeping patients in hospital for treatment that could be given domestically if the need was identified earlier. Also under consideration was the amount of days taken off work by the patients when ill or visiting the clinic – a concern mentioned by some patients we met at the clinic.<br/>
+
-
<i>BCAM0227</i> and P<sub>cblD</sub> BioBricked. <br/>
+
-
The growing PAI-1 system is complemented with the addition of the nanoluc BioBrick.
+
-
</p>        
+
</div>
</div>
-
<div class="col-sm-3 col-xs-3 col-md-3">
+
<div class="col-sm-9 col-xs-9 col-md-9">
 +
<p>
 +
Dimitrios has been busy and managed to biobrick P<sub>cblD</sub>.<br/>
 +
The growing PAI-1 system was complemented with the addition of the nanoluc BioBrick.
 +
The dry team set about modelling the potential savings that could be made from the implementation of The Lung Ranger/L.A.S.S.O. They began by investigating the cost for the NHS of keeping patients in hospital for treatment, which could be given domestically if the need was identified earlier. Also under consideration was the amount of days taken off work by the patients when ill or visiting the clinic – a concern raised by some patients we met at the clinic.<br/>
 +
</p>         
</div>
</div>
</div>
</div>
<div class="row">
<div class="row">
-
<div class=""col-sm-9 col-xs-9 col-md-9">
 
-
<p>
 
<hr>
<hr>
<h3>Week 14</h3>  
<h3>Week 14</h3>  
-
<br/>
+
<div class="col-xs-3">
-
<br/>
+
<img class="centered img-responsive" src="https://static.igem.org/mediawiki/2014/e/ee/Week14Dun.png"/>
 +
</div>
 +
<div class="col-sm-9 col-xs-9 col-md-9">
 +
<p>
 +
The biobrick man strikes yet again.....P<i><sub>manA</sub></i> was successfully cloned into pSB1C3.
More L.A.S.S.O. testing with <i>V. fischeri</i> – this time with plates containing different amounts of bacteria, obtained by serial dilution of an overnight culture. This resulted in our first attempt to map the sensitivity of our device vs. c.f.u. of bacteria.
More L.A.S.S.O. testing with <i>V. fischeri</i> – this time with plates containing different amounts of bacteria, obtained by serial dilution of an overnight culture. This resulted in our first attempt to map the sensitivity of our device vs. c.f.u. of bacteria.
-
P<i>manA</i> BioBricked, one to go!<br/>
+
The BDSF GFP blot was repeated with similar results, and the decision was made to begin removing genes from the system until we identified which one was causing the problem.<br/>
-
The BDSF GFP blot was repeated with similar results, the decision is made to begin removing genes from the system until we find out where the problem is.<br/>
+
Western blots of the DSF system showed successful expression of all three proteins; RpfC, RpfG and Clp.
-
Western blots of the DSF system show good protein expression, GFP assay to follow.<br/>
+
We then set up for an inducible GFP production assay, by spiking overnight cultures of transformed <i>E. coli</i> MC1061 with a range of concentrations of synthetic DSF.
-
Sequencing of the PAI-1 system shows that the nanoluc sequence is missing, hmm….. <br/>
+
Similar to our BDSF system, GFP appeared to be expressed at all concentrations, including 0 µM! We need to come up with a plan, quick!!
 +
Sequencing of the PAI-1 system showed that the nanoluc sequence was missing, hmm….. <br/>
</p>           
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<hr>
<hr>
<h3>Week 15</h3>  
<h3>Week 15</h3>  
 +
<div class="col-xs-3">
 +
<img class="centered img-responsive" src="https://static.igem.org/mediawiki/2014/d/dc/Week15Dun.png"/>
 +
</div>
 +
<div class="col-sm-9 col-xs-9 col-md-9">
 +
<p>
 +
Repeated ligations of PAI-1 system with nanoluc luciferase.
 +
The final sequencing results from the BioBricked <i>rpfc</i> was celebrated with party hats...no more BioBricks for Dimitrios, woohooo!!
<br/>
<br/>
-
<br/>
+
We received our 3D printed L.A.S.S.O., it looked great but didn’t fit together as planned… out with the Stanley knife! No problem.  
-
Repeated ligations of PAI-1 system with nanoluc.<br/>
+
The GFP assay of the DSF system showed similar results to that of the BDSF system; surely not?! The experiment was repeated and the same results obtained. Oh, dear!<br/>
-
RpfC BioBricked, all BioBricks finished, woohoo!<br/>
+
The final L.A.S.S.O. design was almost complete, with only some means of safe disposal for our engineered bacteria to be factored in. We settled on a design that would involve sealed petri-dishes containing freeze-dried <i>E. coli</i> with a one-way valve on the lid, through which a sample of sputum and water would be passed. The plate would then be inserted into the L.A.S.S.O. and all sources of external light eliminated by sliding flaps. The photodiode would pick up luminescence from the luciferase, expressed in response to the bacterial signaling molecule of interest, and send a voltage to the Arduino. This would pass this signal via a µUSB cable to a computer, where an application would interpret the signal into an email containing information about the bacterial species present, which would be sent to a clinician. The plate would then be transferred mechanically into an isolated waste compartment which can be removed and emptied into a biological waste container when full.  
-
Received our 3D printed L.A.S.S.O., it looked great but didn’t fit together as planned… out with the Stanley knife! No problem.  
+
-
GFP assay of DSF system showed similar results to that of the BDSF system, surely not! The experiment was repeated and the same results obtained. Oh, dear!<br/>
+
-
The final L.A.S.S.O. design was almost complete, with only some means of safe disposal of our engineered bacteria to be factored in. We settled on a design that would involve sealed petri-dishes containing freeze-dried <i>E. coli</i> with a one-way valve on the lid through which a sample of sputum and water would be passed. The plate would then be inserted into the L.A.S.S.O. and all sources of external light eliminated by sliding flaps. The photodiode would pick up luminescence from the luciferase, expressed in response to the bacterial signaling molecule of interest, and send a voltage to the Arduino which would pass this signal via a µUSB cable to a computer where an application would interpret the signal into an email containing information about the bacterial species present which would be sent to a clinician. The plate would then be transferred mechanically into an isolated waste compartment which can be removed and emptied into a biological waste container when full.  
+
</p>           
</p>           
-
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-
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-
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-
<p>
 
<hr>
<hr>
<h3>Week 16</h3>  
<h3>Week 16</h3>  
-
<br/>
+
<div class="col-xs-3">
-
<br/>
+
<img class="centered img-responsive" src="https://static.igem.org/mediawiki/2014/1/11/Week16Dun2.png"/>
-
Instead of painstakingly removing each gene, we decided (on the advice of the University’s top microbiologist Prof. Tracy Palmer) to blot the DSF and BDSF systems for GFP when only the promoter/reporter fusions were present. This was a breakthrough as the P<i>manA</i>-<i>gfp</i> fusion still showed GFP expression while the P<i>cblD</i>-<i>gap</i> fusion did not. This lead us to perform a BLAST search of the Clp sequence from the DSF system against the <i>E. coli</i> genome to look for similar transcription factors in the wild type. CRP from <i>E. coli</i> showed significant similarity so we obtained a CRP-deletion mutant (BW25113 ∆CRP) and transformed it with our promoter/reporter fusion in preparation for blotting.<br/>
+
-
<i>BCAM0228</i>-P<sub>cblD</sub>-GFP was set up in <i>E. coli</i> MC1061 for blotting.<br/>
+
-
</p>        
+
</div>
</div>
-
<div class="col-sm-3 col-xs-3 col-md-3">
+
<div class="col-sm-9 col-xs-9 col-md-9">
 +
<p>
 +
Why are our sensors constantly producing GFP??
 +
Instead of painstakingly removing each gene, we decided (on the advice of the University’s top microbiologist Prof. Tracy Palmer) to blot the DSF and BDSF systems for GFP when only the promoter/reporter fusions were present. This was a breakthrough as the P<i><sub>manA</sub></i>-<i>gfp</i> fusion still showed GFP expression while the P<i><sub>cblD</sub></i>-<i>gfp</i> fusion did not.
 +
This lead us to perform a BLAST search of the Clp sequence from the DSF system against the <i>E. coli</i> genome to look for similar transcription factors in the wild type. CRP from <i>E. coli</i> showed significant similarity so we obtained a CRP-deletion mutant (BW25113 ∆CRP) and transformed it with our promoter/reporter fusion in preparation for blotting.<br/>
 +
<i>BCAM0228</i>-P<sub><i>cblD</i></sub>-GFP was set up in <i>E. coli</i> MC1061 for blotting, as there may be potential crosstalk causing GFP to be produced in the absence of our sensor kinase, BCAM0227.<br/>
 +
</p>         
</div>
</div>
</div>
</div>
 +
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-
<div class=""col-sm-9 col-xs-9 col-md-9">
 
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<p>
 
<hr>
<hr>
<h3>Week 17</h3>  
<h3>Week 17</h3>  
-
<br/>
+
<div class="col-xs-3">
-
<br/>PAI-1 system sequencing looked good so was transformed into <i>E. coli</i> MC1061 in preparation for blotting.<br/>
+
<img class="centered img-responsive" src="https://static.igem.org/mediawiki/2014/3/31/Week17Dun.png"/>
-
Western blot of <i>BCAM0228</i>-P<sub>cblD</sub>-<i>gfp</i> showed GFP expression. Contrasted with the negative results from the P<sub>cblD</sub>-<i>gfp</i> blot, this suggests that something native to <i>E. coli</i> is activating BCAM0228. <br/>
+
</div>
-
Western blot of P<sub>manA</sub>-<i>gfp</i> in the CRP deletion strain of <i>E. coli</i> still shows expression of GFP.  
+
<div class="col-sm-9 col-xs-9 col-md-9">
 +
<p>
 +
<br/>The two PAI-1 sensors looked good from sequencing and so was transformed into <i>E. coli</i> MC1061 in preparation for blotting for GFP after induction with synthetic PAI-1 obtained from Sigma Aldrich.<br/>
 +
Western blot of <i>BCAM0228</i>-P<sub><i>cblD</i></sub>-<i>gfp</i> showed GFP expression. Contrasted with the negative results from the P<sub>cblD</sub>-<i>gfp</i> blot, this suggested that something native to <i>E. coli</i> was activating BCAM0228. <br/>
 +
A Western blot of P<sub><i>manA</i></sub>-<i>gfp</i> in the CRP deletion strain of <i>E. coli</i> still showed expression of GFP.  
</p>           
</p>           
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<hr>
<hr>
<h3>Week 18</h3>  
<h3>Week 18</h3>  
-
<br/>
+
<div class="col-xs-3">
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<br/>
+
<img class="centered img-responsive" src="https://static.igem.org/mediawiki/2014/9/9c/Week18Dun.png"/>
-
PAI-1 system blot works! What a relief. After much head-scratching and brow-furrowing over the other two systems it was great to get a positive result. We have learned a lot about the potential cross-talk between signal transduction pathways when they are expressed in different species. We believe that research into untangling these interactions will significantly speed-up the process of applying synthetic biology solutions to real-world problems.  
+
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 +
<div class="col-sm-9 col-xs-9 col-md-9">
 +
<p>
 +
The two PAI-1 sensors containing different promoters both worked to different extents. The sensor containing P<sub><i>lasB</sub></i>-<i>gfp</i> showed slow induction of GFP over time, however the sensor containing P<sub><i>luxR</sub></i>-<i>gfp</i> was initially on but showed increasing GFP production over time.
 +
What a relief. After much head-scratching and brow-furrowing over the other two systems it was great to get a positive result. We have learned a lot about the potential cross-talk between signal transduction pathways when they are expressed in different species. We believe that research into untangling these interactions will significantly speed-up the process of applying synthetic biology solutions to real-world problems.  
<br/>
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See you in Boston!
See you in Boston!
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<a href="" class="btn btn-default toLesson">Previous lesson</a>   
+
<a href="https://2014.igem.org/Team:Dundee/Safety/normal" class="btn btn-default toLesson">Previous Book: Safety & Protocols</a>   
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     <a href="https://2014.igem.org/Team:Dundee/famAlbum" class="btn btn-default toLesson">Next Book: Family Album</a>
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{{:Team:Dundee/Template/welcomeNoteLibrary}}

Latest revision as of 22:38, 17 October 2014

Dundee 2014

Notebook

When it happened

Week 0

A few members of the team, fresh from their exams, began the initial literature reviews necessary to identify the genes and promoters that were required in our biological sensors that would detect and respond to signaling molecules released by Stenotrophomonas maltophilia (DSF), Burkholderia cenocepacia (BDSF) and Pseudomonas aeruginosa (PQS). Finally, rpfC, rpfG, clp and PmanA were to be cloned to detect DSF; BCAM0227, BCAM0228 and Pcbld for BDSF; and pqsR and PpqsA for PQS. Primers were designed (which included restriction sites required for cloning and also HA-tags to detect for protein expression) for the PQS sensing system and ordered from Sigma Aldrich. All sequences were analyzed with Webcutter 2.0 to detect restriction sites that conflict with the BioBrick assembly standard RFC [10]. It was found clp contained an illegal PstI site; BCAM0228 and rpfg contained an illegal EcoRI site. Primers were then designed for use with QuikChange™ Site-Directed Mutagenesis Kit to remove illegal sites. It was decided at this stage that for the DSF system, homologues of all sequences would be taken from Xanthomonas campestris pv. campestris as they have identical functions but contain fewer illegal restriction sites.
However, BCAM0227 was proving problematic. It was so large (3000+bp), and had so many illegal restriction sites, it would have taken the full ten weeks to QuikChange™ them out! We decided to send it for synthetic sequencing by Dundee Cell Products in two separate parts. We hoped this would allow us to successfully ligate the two pieces together into one without mistakes.


Week 1

The team are all together! Work begins…
We began organizing our raw materials, setting up overnight cultures of our vectors (pSB1C3 for BioBricks, and our supervisor’s own pUniprom for experiments) and obtaining gDNA from P. aeruginosa, X. campestris and B. cenocepacia from Drs Robert Ryan and Shi-Qi An from the Division of Molecular Microbiology in the College of Life sciences at the University of Dundee By the end of the week we had cloned pqsR and PpqsA into pSB1C3, phew!
As for the dry-lab, the first week consisted mostly of reading papers and harassing Gillian, our mathematical biologist, for definitions of all the bio-jargon. In fact, most of our early discussions about modelling our systems consisted of furrowed brows from both sides, and questions such as “a differential what?” and “Uhhh, transcriptional whatnow?”


Week 2

In order to test our biological sensors we decided to clone them into pUniprom, a high copy-number plasmid which has a large and varied multiple cloning site downstream of a strong, constitutive promoter: Ptat. In order to arrange our sequences in such a way that there would be no leakage of our reporter, we had to employ a bit of cloning trickery by inserting our sensing and responding fragments in opposite orientations. This involved cloning them into separate fragments and then flipping them round into pUniprom. And so to the bench we went!
Now that the plan for the plasmid was in place, we began to enter all the information onto Netlogo to model how the system would behave in the presence of different concentrations of exogenous PQS.


Week 3

While members of the team continued to work on building the PQS sensor, we also got started on planning and constructing the DSF sensor. From this point onwards we decided to use GFP rather than mCherry, as we already had antibodies against it for blotting later. Our desired DSF sensor has four sensory components! This posed a bit of a problem for cloning, as we thought we would need to use more restriction enzymes than we had access to. The solution? Order primers that include a 5’ BglII site and 3’ BamHI-XbaI sites. This way, fragments could be cloned in sequentially. Each new insert could be cut with BglII-XbaI, and the ever-growing vector cut with BamHI-XbaI. This is because the BglII and BamHI overhangs are complementary, but upon ligation leave a scar that is not recognized by either enzyme (see below). The 3’ BamHI-XbaI site allows this process to be repeated indefinitely. Woo, idempotency! A lot of cloning followed...


Week 4

With lots of cloning, comes lots of sequencing… which was all kindly carried out by the sequencing service downstairs from our lab. To help us along the way Professor Philip Cohen kindly granted us 100 free sequencing runs (which we quickly exceeded!). After every cloning step for building our PQS and DSF sensor, we sent a sample to be sequenced – the results were a source of merriment and heartbreak in equal measure…it turned out that our cloned PQS sensor wasn’t quite right so we spent the week trying to rectify this.
We also began the lengthy task of removing all the illegal restriction sites from the fragments bound for BioBricking; and so began Dimitrios’ epic journey into the world of BioBricks!
It turned out, (after a bit more sifting through papers), that the Netlogo model for PQS was not quite right. While we figured that out, we began to calculate the ordinary differential equations for the same system.


Week 5

We successfully biobricked PpqsA!
Thankfully we had succesfully ligated PpqsA with pqsR-HA into pUniprom. After western blotting the PQS system, we obtained results which showed that PqsR was being expressed. We then obtained synthetic PQS from Sigma Aldrich to test this sensor for the production of GFP. Meanwhile...the dry team were finding the the DSF model slightly harder to work with than PQS (sorry guys!), as it contained a lot of components; our first model started with about 12 equations! We were able to reduce these down and simplify the model, which enabled us to input them into MATLAB and produce some graphs. We had a few problems determining exactly what our GFP production was reliant on, but after a lot of work on our blackboard, we came to a conclusion! Again, our deterministic model allowed us to change our initial conditions allowing us to see what would happen.
A lot of stochastic modelling happened during this week; PQS wild type and PQS E.coli being our priority. Adding in an external signal proved a little difficult, as we did not get the expected results! There was a lot of trial and error in trying to match up parameters from MatLab and Maple, but by the end of the week we thought we were there! Netlogo was also coming along nicely, with PQS wild type and PQS E. coli finished! BDSF E. coli was almost finished too, with only DSF to tackle after that!


Week 6

We were all excited to test our first sensor, an inducible GFP production assay was set up, by spiking overnight cultures of transformed E. coli MC1061 with a range of concentrations of synthetic PQS. Unfortunately, we obtained no mCherry expression....along with a lot of perplexed biologists! We successfully removed the first illegal site from rpfC. Meanwhile clp BioBricking was underway, and work had begun on the BDSF system. We were halfway through the 10 weeks and we were feeling productive! The dry lab were certainly ahead of the game as far as BDSF was concerned; after working through the mammoth DSF system, the closely related two-component BCAM0227/BCAM0228 system was a breeze. In fact, with such a head-start it was decided that there would be a presentation given by the maths boffins of the team entitled: “Modelling for the Perplexed Biologists and Dave”. This was an interactive lesson on how to apply equations to biological systems which helped the lab-rats get to grips with how the figures being generated by the dry team could inform the final design of the biological systems. By the end of the week, rpfG, rpfC and clp were cloned into pUniprom!
Around this time, the “Device Committee” was formed; a small group of wet and dry members who would begin the design of a physical unit to house and interpret the output from our engineered bacteria. This began with background reading on creating a GFP-fluorescence reading device. Order initial parts to build a light sensing device based on LED light source so we could modulate the light levels. We considered that we would have to use MatLab to carry out calculations. Our visits to the clinic took a more direct focus, and during the interviews we were conducting each week, we started asking patients for their thoughts on the design of the physical detector.


Week 7

Sequencing results for rpfG QuikChange™ showed that it was actually rpfC…oops! Steps were made to rectify this quickly!
All promoters had now been successfully cloned and sequenced and so the job now was to clone them along with their fluorescent reporters into pUniprom. Our two sequences of BCAM0227 were successfully returned from the sequencing company, Dundee Cell Products, for us to work with. The two separate sequences were digested, and work commenced to try and ligate them together into pbluescript...easier said than done!
Initial experiments with a photodiode, Arduino and a green LED for the physical device, commenced. First designs showed us that we would need an excitation source to induce fluorescence, this would necessitate the inclusion of filters and amplifiers…extremely complicated! Discussions were had with the entire team about eventually using firefly luciferase as a reporter in the place of fluorescent proteins.


Week 8

After lots of modelling of the PQS system, and trying to troubleshoot why our system was not expressing mCherry, the decision was made to design another two biological sensors for P. aeruginosa, which would detect another quorums sensing molecule Pseudomonas autoinducer 1 (PAI-1). Lots of work for the wet team!
An overnight culture of E. coli MC1061 transformed with the DSF plasmid was pelleted and prepared for western blotting for detection of our proteins - alas, RpfC-HA is not being expressed! Back to the cloning board… BioBricking of rpfG was undertaken upon receiving good news from sequencing that our illegal EcoRI restriction site had been removed.


Week 9

The tricksome BCAM0227 was successfully ligated together into one gargantuan sequence, and swiftly cloned into pUniprom (already containing the Pcbld-gfp fusion).
BCAM0228 QuikChange of the illegal EcoRI site was complete and sent for sequencing to confirm this was actually the case. The Device Committee met up with Dr. Stephen Reynolds from the University’s physics department, who helped us to optimize our light-detecting circuit. We constructed a crude (but effective!) Faraday cage from aluminium foil and a cardboard box to eliminate electrical interference from the buzzing computers in the dry lab…
We managed to clone rpfC into pUniprom, along with the rest of the DSF system; time for some tests!


Week 10

Sequencing results came back for the QuikChanged BCAM0227 and confirmed that the EcoRI site had been removed and so we handed it over to Dimitrios to clone it into pSB1C3.We obtained a culture of Vibrio fischeri from Dr Sarah Coulthurst’s lab, and began streaking plates to test out our physical device for detection of the bioluminescence from V. fischeri luciferase – it worked! At this point our device was essentially half of a water bottle covered in insulating tape, an Arduino and a voltage meter...However, we had come up with a product name: the Light Amplifying Signal Sensing Object, because every good cowboy needs a L.A.S.S.O., right?! It was time for a more robust design; our thoughts moved to 3D printing, and iGEM alumnus and polymath Nasir Ahmad showed us how to draw up plans using Google Sketch.


Week 11

At this stage, we had all of our systems (barring PAI-1) cloned into pUniprom and ready for blotting. So with a little, (actually, rather a lot), of help from "The Blotfather" Prof. Frank Sargent, we set to the task with all the elation of a team that can see the end of cloning in sight.
Meanwhile, some of the wet team set to the noble task of cloning our replacement Pseudomonas system. Luckily, all the components we needed were included in the 2014 iGEM distribution pack so we stabbed, rehydrated and got to work. We started by using the Ptet BioBrick as a vector and cloned in lasR downstream.
The Device Committee met with Dr. Mike MacDonald from the Institute for Medical Science and Technology (IMSAT) to discuss plans for building a physical device. They learned from him the importance of following international standards of operation (ISOs). From this point on we endeavoured to follow ISOs 13485 (medical devices) & 9001(general quality management) so that, if the device were to be taken on by a company, our design and parts would be easily replicable.


Week 12

After western blotting the BDSF system, we obtained results which showed that both BCAM0227 and BCAM0228 were both being expressed. We then set up for an inducible GFP production assay, by spiking overnight cultures of transformed E. coli MC1061 with a range of concentrations of synthetic BDSF. Unfortunately, GFP appeared to be expressed at all concentrations, including 0 µM! This experiment clearly needed to be repeated... The cloning of the two PAI-1 sensors was continued, by ligating two different promoters downstream of LasR; Plasb and PluxR. The Device Committee were having a great time designing the L.A.S.S.O.; a cavity here, a plunger there, maybe some springs... taking into account the ISO requirements as specified by Dr MacDonald.


Week 13

Dimitrios has been busy and managed to biobrick PcblD.
The growing PAI-1 system was complemented with the addition of the nanoluc BioBrick. The dry team set about modelling the potential savings that could be made from the implementation of The Lung Ranger/L.A.S.S.O. They began by investigating the cost for the NHS of keeping patients in hospital for treatment, which could be given domestically if the need was identified earlier. Also under consideration was the amount of days taken off work by the patients when ill or visiting the clinic – a concern raised by some patients we met at the clinic.


Week 14

The biobrick man strikes yet again.....PmanA was successfully cloned into pSB1C3. More L.A.S.S.O. testing with V. fischeri – this time with plates containing different amounts of bacteria, obtained by serial dilution of an overnight culture. This resulted in our first attempt to map the sensitivity of our device vs. c.f.u. of bacteria. The BDSF GFP blot was repeated with similar results, and the decision was made to begin removing genes from the system until we identified which one was causing the problem.
Western blots of the DSF system showed successful expression of all three proteins; RpfC, RpfG and Clp. We then set up for an inducible GFP production assay, by spiking overnight cultures of transformed E. coli MC1061 with a range of concentrations of synthetic DSF. Similar to our BDSF system, GFP appeared to be expressed at all concentrations, including 0 µM! We need to come up with a plan, quick!! Sequencing of the PAI-1 system showed that the nanoluc sequence was missing, hmm…..


Week 15

Repeated ligations of PAI-1 system with nanoluc luciferase. The final sequencing results from the BioBricked rpfc was celebrated with party hats...no more BioBricks for Dimitrios, woohooo!!
We received our 3D printed L.A.S.S.O., it looked great but didn’t fit together as planned… out with the Stanley knife! No problem. The GFP assay of the DSF system showed similar results to that of the BDSF system; surely not?! The experiment was repeated and the same results obtained. Oh, dear!
The final L.A.S.S.O. design was almost complete, with only some means of safe disposal for our engineered bacteria to be factored in. We settled on a design that would involve sealed petri-dishes containing freeze-dried E. coli with a one-way valve on the lid, through which a sample of sputum and water would be passed. The plate would then be inserted into the L.A.S.S.O. and all sources of external light eliminated by sliding flaps. The photodiode would pick up luminescence from the luciferase, expressed in response to the bacterial signaling molecule of interest, and send a voltage to the Arduino. This would pass this signal via a µUSB cable to a computer, where an application would interpret the signal into an email containing information about the bacterial species present, which would be sent to a clinician. The plate would then be transferred mechanically into an isolated waste compartment which can be removed and emptied into a biological waste container when full.


Week 16

Why are our sensors constantly producing GFP?? Instead of painstakingly removing each gene, we decided (on the advice of the University’s top microbiologist Prof. Tracy Palmer) to blot the DSF and BDSF systems for GFP when only the promoter/reporter fusions were present. This was a breakthrough as the PmanA-gfp fusion still showed GFP expression while the PcblD-gfp fusion did not. This lead us to perform a BLAST search of the Clp sequence from the DSF system against the E. coli genome to look for similar transcription factors in the wild type. CRP from E. coli showed significant similarity so we obtained a CRP-deletion mutant (BW25113 ∆CRP) and transformed it with our promoter/reporter fusion in preparation for blotting.
BCAM0228-PcblD-GFP was set up in E. coli MC1061 for blotting, as there may be potential crosstalk causing GFP to be produced in the absence of our sensor kinase, BCAM0227.


Week 17


The two PAI-1 sensors looked good from sequencing and so was transformed into E. coli MC1061 in preparation for blotting for GFP after induction with synthetic PAI-1 obtained from Sigma Aldrich.
Western blot of BCAM0228-PcblD-gfp showed GFP expression. Contrasted with the negative results from the PcblD-gfp blot, this suggested that something native to E. coli was activating BCAM0228.
A Western blot of PmanA-gfp in the CRP deletion strain of E. coli still showed expression of GFP.


Week 18

The two PAI-1 sensors containing different promoters both worked to different extents. The sensor containing PlasB-gfp showed slow induction of GFP over time, however the sensor containing PluxR-gfp was initially on but showed increasing GFP production over time. What a relief. After much head-scratching and brow-furrowing over the other two systems it was great to get a positive result. We have learned a lot about the potential cross-talk between signal transduction pathways when they are expressed in different species. We believe that research into untangling these interactions will significantly speed-up the process of applying synthetic biology solutions to real-world problems.

Time to pack up the lab and hand over our equipment to the new PhD students for training, it’s been a rollercoaster of a project that every one of us has benefited from in ways we will likely still be discovering years from now.

See you in Boston!