Team:MoWestern Davidson/notebooks
From 2009.igem.org
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WE NEED TO ADD A SITE MAP
We could try and somehow take the rolling stones' red lips picture and make the tongue green...or something.
This could tied to GFP and we need to incorprate an E. coli bacterium into the mix.
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Week 1 (May 25-May 29)
The Missouri Western students came to Davidson to finalize the research agenda for the summer. Both the biology and math aspects of the project were discussed in detail. By the end of the week, the team had unified around applications of the Satisfiability (SAT) problem to the genome of E.coli via the use of frameshift suppressor tRNAs.
We needed to design and engineer a reporter gene that the tRNA would suppress. Therefore, our research would consist of 2 main tracks: tRNA project and the 5mer Reporter Project.
Week 2 (June 1-June 5)
tRNA Project
We began to plan the construction of a 1-SAT model that would include a modified reporter gene suppressed by its respective tRNA.
The two campuses decided to split up the list of tRNAs according to percent suppression. Missouri Western took CUACC, AGGAC, CCAAU, CUAGC, CUACU, and CCACC. Davidson took CUAGU, CCACU, CGGUC, CCCUC, CCAUC-9 and CCAUC-10. We requested the sequence for our tRNAs from Dr. J. Christopher Anderson. After recieving them, we planned their construction via oligo assembly.
By the end of the week, we had planned to use 4 total oligos for our tRNAs.
5mer Reporter Project
In order to minimize major changes made to the protein structures and gene, we decided to place our 5 base pair addition upstream of our reporter protein. We accomplished this using PCR. We manipulated the PCR primers by designing our forward primer to include ATG, our 5mer, and the first half of the reporter protein up to a restriction site of our choice.
We wanted 1 fluorescence gene and 1 antibiotic resistance gene on each campus. After careful consideration of which reporters had the most "hardy" restriction sites, we decided upon RFP and Tet Resistance on the Davidson campus and GFP and Chlor Resistance on the Missouri campus.
Week 3 (June 8-June 12)
tRNA Project
After editing the first draft of 4 oligos, we devised a tRNA constructed of 7 oligos of shorter lengths to reduce the chance of mutations. We assembled our tRNA from these oligos and ligated/transformed the assembly. By the end of the week, we had obtained colonies from these transformations.
5mer Reporter Project
We chose NcoI as the restriction site in the RFP and BamHI as the site in Tet Resistance. We ordered the oligos of our primers. The forward primer was different for each of the 5 different 5mers on Davidson's campus and 6 different 5mer's on Missouri's campus. We only needed one reverse primer for each reporter gene we used. We carried our PCR using wild type RFP and Tet plasmids as our respective reporter templates.
We only used an aliquot amount to run a gel and verify that the sizes of the PCR fragments included the beginning of the reporter (with ATG and our 5mer) to the restriction site we chose.
Week 4 (June 15- June 19)
tRNA Project
We found that the variable to negative ratio of tRNA colonies was about 2 to 1. We saved liquid cultures of these and we re-ligated and re-transformed the tRNAs again.
Later that week, each lab member "adopted" a specific 5mer and tRNA for the rest of the summer. After verifying and plating tRNAs of correct insert size, we prepared samples of some tRNAs for sequencing.
5mer Reporter Project
We ligated cleaned and digested PCR inserts into vectors and transformed them. The vectors had been digested with EcoRI and either BamHI (Tet) or NcoI (RFP). Unfortunately, no colonies appeared on plates the next day. We repeated PCR to construct the first half of the reporter. We ended the week by verifying the insert sizes and cleaning the insert.
Week 5 (June 22-June 26)
tRNA Project
Sequencing for the tRNAs initially gave us 2 100% matches. The rest of the tRNAs had at least 1 ambigious nucleotide. We decided to resequence these tRNAs. We also decided that we would use pBad as the promoter for these tRNAs. We decided that to use the pBad promoter for the tRNAs because it maintains low expression of the tRNA in cells, which is best for the them. We also entered our tRNAs into the parts registry. Suppressor tRNA Parts
5mer Reporter Project
We re-verified our PCR inserts and after cleaning/digesting them, re-ligated and re-transformed them. We obtained colonies this second time. After PCR screening the colonies, we chose samples that looked the right size for sequencing. At the end of the week, we entered our 5mer reporters into the parts registry. 5mer Reporter Parts
Week 6 (June 29- July 3)
tRNA Project
We digested the tRNAs with XbaI and PstI to isolate the insert. We gel purified the insert, and ligated it to pBad vector. By the end of the week, we PCR screened the colonies from the ligations.
5mer Reporter Project
The sequencing that returned from our 5mer Reporter was quite messy. We decided to use a different mini prep kit (switched from Zyppy to Promega) to re-sequence our 5mers.
Week 7 (July 6-July 10)
tRNA Project
After mini prepping viable clones of the pBad-tRNA ligation, we decided that we wanted to see how the cells would function with more than one pBad-tRNA gene. During the week, digested pBad-tRNA plasmid with XbaI/PstI and SpeI/PstI to construct an insert and vector respectively.