This week we made great progress into designing our own constructs for the comparative circuit. Many challenges in the design of the complementary sequences were overcome and
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This week we made great progress into designing our own constructs for the comparative circuit. Many challenges in the design of the complementary sequences were overcome such as the creation of scars and the standard we would design it for. The amount of lab work has definitely picked up. We are extremely close to creating our own BioBricks. Hopefully by next week, we will have them.
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The amount of lab work has picked up. We are extremely close to creating our own BioBricks. Hopefully by next week, we will have them.
This week we made great progress into designing our own constructs for the comparative circuit. Many challenges in the design of the complementary sequences were overcome such as the creation of scars and the standard we would design it for. The amount of lab work has definitely picked up. We are extremely close to creating our own BioBricks. Hopefully by next week, we will have them.
Day 1 (30/07/12)
Research and Meetings
Khadija and Pascoe found encountered obstacles with stop codons over the weekend; two solutions might be a scaffold construction or the assembly using standard 23. The team leans towards the assembly 23 standard as it's less risky than the scaffold, however is is decided that further research is needed in order to make an informed decision.
Two main constructs were developed; one saw overlapping stands, the other saw strands together. Khadija produced a logic table of codons that could bind to one another. Amy also came to visit in order to look at the studio we bfor our film being recorded on Wednesday.
Labs
Joy and Lukas continued the planning of the ligation of the B-M/M-B promoter into the pSB1C3 backbone which will give us our first two BioBricks. As the B-M fragment with the correct prefix and suffix endings was ready from last week, the protocol iGEM protocol was performed.
Following the ligation, Rebecca transformed the potential Bio-Brick into Bioline competent alpha cells with the created plasmid and the cell cultures were grown on the appropriate media (now containing 100ug/µl of chloramphenicol) at 37 °C over night.
Observation the cells transformed on Friday (that were stored in the fridge after the initial incubation for 24 hours), Russell and Rachel found that the cultures had not grown as much as they would have liked. Therefore the plates were returned to the 37 °C incubator to grow some more overnight.
Day 2 (31/07/12)
Research
Russell and Rachel researched nitrite reductases (NOSs) and their sequences, to be able to determine it functionality as a reporter in the NO sensing gene construct and its ability to raise No levels to toxic levels. In addition the sequences were observed to judge whether it would be feasible to get them synthesised.
The whole team worked together with Khadija and Pascoe on the complementary DNA sequences for the comparative circuit; four members working on Khadija's logic map and three with Pascoe's idea.
Labs
As the colonies transformed with the ligation product of B-M in pSB1C3 from yesterday showed no growth, Rebecca redid transformation using the same ligation product and incorporated untransformed alpha cells as a negative control and chloramphenicol resistant PyeaR cells as a positive controls.
More chloramphenicol plates were poured to stock pile for the transformation of ligation products in the coming weeks. The transformants from yesterday were incubated for longer in hope that colonial growth would appear.
Lukas and Joy isolated plasmid DNA from "E.coli" containing the hybrid promoter M-B plasmid. They then double digested the DNA using EcoR1 and Pst1 to separate the M-B promoter with iGEM prefix and suffix attached. Double digests with Sac1 and Spe1 of the same plasmid were also performed as validation of the isolated plasmid. Both digests were run on an agarose gel.
The validation digest was also carried out on the B-M plasmid that had been used in the ligation on Monday to exclude the quality of the starting material of the transformation as a source of error.
After incubating the E. coli cultures that had been transformed with RFP, eCFP and AraC promoter for longer, there was some success as more colonies were oberved on almost all the plates plates. Russell and Rachel inoculated 5 ml tubes of LB media (+ 5µl ampicillin) with transformed E. coli as follows:
- Two tubes of RFP-transformed E. coli from different colonies on the 200µl plate
-Two tubes of eCFP-transformed E. coli from different colonies on the 200µl plate
- Four tubes of AraC Promoter-transformed E. coli from different colonies on the 200µl plate (due to the fact that promoters were needed for each of the fluorescent proteins, we decided to create double the amount).
The inoculated media was placed in the 37 °C agitator and left overnight to grow. The protocol for this can be found Here
Day 3 (01/08/12)
The JK-R5-PL Construct
Labs
Rachel and Russell checked the inoculated media from the day before and observed that bacterial growth had not occurred enough to perform a likely successful experiment. Therefore it was decided to continue the incubation before attempting a DNA isolation vie mini prep.
Again repeated transformation of B-M/M-B in pSB1C3 did not yield viable cells. But he negative control showed no growth and the positive controlled did showed growth from which it was concluded that the error must lie with the ligation and not with the transformation.
Rebecca purified the B-M insert (cut from pUC57 with EcoRI and PstI) cut out from the agarose gel slice and frozen the previous night. This was performed using a Promega gel purification kit to minimise the error that might be introduced with the Bioline kit. The protocol is on the lab protocol page. The isolated sample was run on an agarose gel.
Research
In the morning Khadija, Pascoe, Rebecca and Russell looked at one of the proposed constructs and worked at producing a DNA sequence that forms two complimentary strands that would bind together once transcribed to mRNA. After a few hours of work and lots of adjustments and edits we finally had our construct which we named the JK-R5-PL construct (using the initials of the team members). The construct is the coming-together of two separate constructs which would be in between the promoter and reporter sequences of the gene we were producing. We were pleased with the JK-R5-PL construct because it meant the ribosome binding site of both original constructs was covered, meaning that the two reporter proteins would not be expressed resulting in the first step of the comparator circuit being completed!
Video
Amy Congdon visited along with two of her colleagues to film for the final presentation video. The artist team had produced some fantastic visual adaptations of cancer cells and the bacteria climbing over them to analyse the environment and act upon the information received. We also filmed the more concept-based aspect of the video, which looks at a future world where comparator circuit-containing bacteria are commonplace in all human beings assessing the body for disease and reporting the results back to the person.
Day 4 (02/08/12)
WE RECEIVED A LETTER FROM DAVID ATTENBOROUGH!!!
Posters for our human outreach event at the Forum were returned from the print shop and we were getting ready to start putting them up.
Labs
As the gel purification of M-B/B-M fragments did not yield DNA samples of high concentrations and we suspected that this might be the cause of the failed ligations, Joy and Lukas performed a PCR on the M-Band B-M genes in pUC57 to increase the amount of DNA we had at hand. The PCR was performed with a negative control and it is important to note that the primers used were standard amplification primers for the pUC57 backbone which allowed us to amplify the hybrid promoters as well as the iGEM suffix and prefix.
Russell and Rachel performed DNA isolations on the samples of cells cultures containing the RFP, eCFP and AraC promoter BioBricks. The samples were put on ice for validation gel electrophoresis the next day. A Promega plasmid isolation kit was used and for each original cell culture a small amount was stored in the fridge as a back-up in case of any problems with the plasmid isolation.
Day 5 (03/08/12)
To check the DNA concentrations of B-M and M-B PCR products, nano drops were performed on all samples was used. We found that the DNA concentrations off all products were above 300ng/µl. To purify the samples and prevent primers, salt and buffers from interfering with downstream applications of the M-B/B-M genes, a Promega PCR cleanup kit was used.
Lukas carried out a double (EcoRI + PstI) and single (EcoRV) restriction digest on PyeaR + GFP (BBa_K381001). The single digest was used to validating whether the isolated plasmid DNA is in fact BBa_k381001. The double digest would yield a linearised pSB1C backbone and fragments of the PyeaR + GFP BioBrick. They will be utilised as a positive control in ligations and transformations. Gel electrophoresis was used to visualise the DNA fragements. The single digest was successful linearising the plasmid and thus confirmed that the DNA contained in the samples was in fact PyeaR + GFP. The double digest was not successful and needed to be repeated.
A double (EcoRI + PstI) and single (BanHI) digest was carried out on the PCR amplification of B-M/M-B. The enzymes EcoR1 and PstI will release the promoter sequence from the primer sequences leaving them with sticky ends of the IGEM prefix and suffix. The single digest was used for validation.
Following the restriction digest, the DNA was nanodropped to check the concentrations and then run on a 1.4% agarose gel. If the PCR cloning, purification and digestion were succesful, 251bp fragments should be produced. The gel showed shadowing and was not completely clear. The gel will have to be rerun.
The BamH1 digested products were run on a gel. It showed 200bp fragments, suggesting that the insert was produced.
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