Team:Waterloo
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<br><h4 style="color:#0077be">1.1 A Little Bit About Group 1 Introns</h4> | <br><h4 style="color:#0077be">1.1 A Little Bit About Group 1 Introns</h4> | ||
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- | All group I introns in bacteria have presently been shown to self-splice (with few exceptions) and maintain a conserved secondary structure comprised of a paired element which uses a guanosine (GMP, GDP or GTP) cofactor. Conversely, only a small portion of group II introns have been verified as ribozymes; they are not related to group I introns and generally have too many regulators to easily work with. It is mainly the structural similarity of these introns that designates them to group II. We will mainly be working with group I introns, such as the <i>Staphylococcus</i> phage twort.ORF143. | + | All group I introns in bacteria have presently been shown to self-splice (with a few exceptions) and maintain a conserved secondary structure comprised of a paired element which uses a guanosine (GMP, GDP or GTP) cofactor. Conversely, only a small portion of group II introns have been verified as ribozymes; they are not related to group I introns and generally have too many regulators to easily work with. It is mainly the structural similarity of these introns that designates them to group II. We will mainly be working with group I introns, such as the <i>Staphylococcus</i> phage twort.ORF143. |
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Group I introns contain a conserved core region consisting of two helical domains (P4–P6 and P3–P7). Recent studies have demonstrated that the elements required for catalysis are mostly in the P3 to P7 domain. They are ribozymes that consecutively catalyze two trans-esterification reactions that remove themselves from the precursor RNA and ligate the flanking exons. They consist of a universally conserved core region and subgroup-specific peripheral regions, which are not essential for catalysis but are known to cause a reduction in catalytic efficiency if removed. In order to compensate for this, a high concentration of magnesium ions, spermidine or other chemicals that stabilize RNA structures can be added. Thus, the peripheral regions likely stabilize the structure of the conserved core region, which is essential for catalysis. | <br><p>
Group I introns contain a conserved core region consisting of two helical domains (P4–P6 and P3–P7). Recent studies have demonstrated that the elements required for catalysis are mostly in the P3 to P7 domain. They are ribozymes that consecutively catalyze two trans-esterification reactions that remove themselves from the precursor RNA and ligate the flanking exons. They consist of a universally conserved core region and subgroup-specific peripheral regions, which are not essential for catalysis but are known to cause a reduction in catalytic efficiency if removed. In order to compensate for this, a high concentration of magnesium ions, spermidine or other chemicals that stabilize RNA structures can be added. Thus, the peripheral regions likely stabilize the structure of the conserved core region, which is essential for catalysis. |
Revision as of 02:01, 4 October 2012
In Vivo Protein Fusion Assembly Using Self Excising Ribozyme
ABSTRACT
Waterloo's 2012 iGEM project is a continuation of the 2011 project, In Vivo Protein Fusion Assembly Using Self Excising Ribozymes. This year, our hope is to complete the project with the aim of potentially designing future projects that incorporate this system.
Self-excising ribozymes are RNA sequences with catalytic properties which allow them to remove themselves and the regions they flank from an RNA sequence. These are introns; however, with ribozyme self-excision the introns are removed without the aid of protein enzymes. In our project we use self-excising ribozymes to remove an extraneous sequence, an intron, which interrupts the coding sequence of GFP. Upon successful removal of the intron, the two halves of GFP should be ligated together and be able to be translated into a fully functional GFP. By showing that functional fusion proteins can be assembled in-vivo using this system we open up possibilities such as the addition of recombination sites to allow gene shuffling, and regulatory sequences which function at the DNA level but are removed at the RNA level to create functional proteins.
WE WOULD LIKE TO THANK OUR GENEROUS SPONSORS.
Project
The goal of Waterloo's 2011 iGEM project is to implement self-excising ribozymes (introns) as BioBricks. But first, what are self-excising ribozymes? Ribozymes are ribonucleic acid (RNA) enzymes and enzymes are reaction catalysts. So, ribozymes are just RNA sequences that catalyze a trans-esterification reaction to remove itself from the rest of the RNA sequence. Essentially, these are considered introns, which are intragenic regions spliced from mRNA to produce mature RNA with a continuous exon sequence. Self-excising introns/ribozymes consist of type I and II introns. They are considered self-splicing because they do not require proteins to intitialize the reaction. Therefore, by understanding the sequences and structure of these self-excising introns and making them useable, we can use them as tools to make other experiments easier.
1.0 INTRODUCTION
This design provides a reasonable basis to implement in vivo applications involving RNA level regulatory sequences. The fusion proteins produced surpass what is strictly coded in the DNA. As a result of incorporating ribozyme segments in between two halves of the protein coded in the DNA construct, a regulatory sequence such as a recombination site could be included. Since recombination sites can interrupt the functional production of a protein if fully translated, resulting in excess amino acids in the polypeptide, the incorporated ribozyme portions remove them before the translation phase of gene expression so that a functional protein is produced. For example, Cry proteins, which account for the insecticidal activity (toxicity) of Bacillus thuringiensis, could be the fusion protein produced for a particular insecticide. Using our experimental design, the sequence containing the code for the Cry protein at the DNA stage is split by ribozyme segments containing a recombination site. In this case, the recombination site is the regulatory sequence that will be removed once transcribed into RNA. At the DNA level, recombination will occur, exchanging DNA strand segments. Therefore, when the shuffled DNA sequence is transcribed into RNA, the recombination site is spliced out of the sequence with the ribozymes, and the resulting RNA code is different than that of the un-shuffled code. Consequently, the translated Cry protein is different. This system would oppose pesticide resistance among the target organism.
1.1 A Little Bit About Group 1 Introns
All group I introns in bacteria have presently been shown to self-splice (with a few exceptions) and maintain a conserved secondary structure comprised of a paired element which uses a guanosine (GMP, GDP or GTP) cofactor. Conversely, only a small portion of group II introns have been verified as ribozymes; they are not related to group I introns and generally have too many regulators to easily work with. It is mainly the structural similarity of these introns that designates them to group II. We will mainly be working with group I introns, such as the Staphylococcus phage twort.ORF143.
Group I introns contain a conserved core region consisting of two helical domains (P4–P6 and P3–P7). Recent studies have demonstrated that the elements required for catalysis are mostly in the P3 to P7 domain. They are ribozymes that consecutively catalyze two trans-esterification reactions that remove themselves from the precursor RNA and ligate the flanking exons. They consist of a universally conserved core region and subgroup-specific peripheral regions, which are not essential for catalysis but are known to cause a reduction in catalytic efficiency if removed. In order to compensate for this, a high concentration of magnesium ions, spermidine or other chemicals that stabilize RNA structures can be added. Thus, the peripheral regions likely stabilize the structure of the conserved core region, which is essential for catalysis.
1.2 Trans-Esterification Reactions
The secondary structures, such as P6, formed by group I introns facilitates base pairing between the 5' end of the intron and the 3' end of the exon, as well as generates an internal guide sequence. Additionally, there is a pocket produced to encourage binding of the Guanosine cofactor. The Guanine nucleotide is placed on the first nucleotide of the intron. The 3'OH of the Guanosine group nucleophilically attacks and cleaves the bond between the last nucleotide of the first exon and the first nucleotide of the 5' end of the intron; concurrently, trans-esterification occurs between the 3'OH and the 5'phosphorous from the 5' end of the intron. Subsequent conformational rearrangements ensure that the 3'OH of the first exon is placed in proximity of the 3' splice site. In this way, further trans-esterification reactions and splicing occurs.Retreived June 21, 2011 from Self-Splicing RNAs [1] This diagram shows the trans-esterification reaction and splicing of group I introns from a sequence.
1.3 Fusion Proteins
Fusion proteins are combined forms of smaller protein subunits and are normally constructed at the DNA level by ligating portions of coding regions. A simple construction of traditional fusion protein involves inserting the target gene into a region of the cloned host gene. However, the subsequent project design, in its simple construction, interrupts the cloned protein with ribozyme sequences flanking a stop codon. The method proposed deals with excision and ligation at the RNA level, therefore, the unaltered DNA sequence does not code for a functional protein. The ligation of protein coding sequences can create functional fusion proteins for many applications including antibody or pesticide production; however, this method of production is limited to producing the same fusion protein each time since the sequence is not modified in between the transcription and translation phases of gene expression. One disadvantage of this is the resultant resistance of a pathogen to antibodies or a target organism to pesticides. For example, a specific pesticide like Cry toxin may eventually be ineffective to its target plant if subsequent plant generations inhibit its uptake, overproduce the sensitive antigen protein so that normal cellular function persists, reduce the ability of this protein to bind to the pesticide or metabolically inactivate the herbicide. Similar mechanisms contribute to antibiotic resistance. Any resistant organisms will inevitably prevail in subsequent generations. Recombination sites could potentially be incorporated into the subsequent project design to circumvent some of the difficulties with traditional fusion proteins as a result of host resistance. However, recombination sites may interrupt the functional fusion protein from forming. Ribozyme segments at the RNA regulation level can potentially remove disrupting sequence after such shuffling occurs. Therefore, the intervening sequence maintains its DNA level functionality but is removed when no longer needed at the RNA level. Fusion protein design focused on the DNA level does not have this dynamic regulation.1.4 The Cre-Lox System
In bacteriophage P1 exists the cre enzyme and recognition sites called lox P sites. This viral recombination system functions to excise a particular DNA sequence by flanking lox P sites and introduce the cre enzyme when the target is to be excised. The cre enzyme both cuts at the lox P site and ligates the remaining sequences together. The excised DNA is then degraded. This is similar to our project design; however, instead of requiring the addition of an enzyme at the desired excision time, the self-excising nature of ribozymes automatically functions during the normal process of gene expression (RNA level).2.0 PROJECT IN DETAILS
2.1 EXPERIMENTAL DESIGN
Our protocol will involve the insertion of a functional protein divided by the self-removing elements, between CUCUUAGU and AAUAAGAG in the P6 region of twort.ORF143. GFP (green fluorescent protein) is split into two parts, which will be referred to as GFP1 and GFP2. With a constitutive promoter, GFP1 and GFP2 will be separated by a class 1 A2 intron split into two (for now, IN1 and IN2) sequences that flank another sequence inserted into the P6 loop, which was chosen because anything attached to this region will remain outside the protein. Note that this experimental design also contains an in frame stop codon, which is expected to be spliced out of the sequence with IN1 and IN2 and will utilize the RFC53 convention. Following GFP2 is a transcriptional terminator (TT). The method of making this construct is detailed in RFC53. Below is Figure 1 through Figure 3. They illustrate the order of parts in the design and the trans-esterification reaction that results in a function GFP:
Figure 2 shows the experimental design of the sequence immediately following transcription. It contains a constituent promoter, RBS Ribosome Binding Site), GFP1, IN1, in-frame stop codon, IN2, GFP2 and TT. The dotted lines and scissors indicate that the introns will be spliced out of the sequence at these points, however, the introns are self-excising.
Figure 3 is a representative view of the sequence folding in order to catalyze the trans-esterification reaction, however, there are many hairpin loops actually formed. This is the process of post-transcriptional modification. Specifically, Group I intron splicing events utilize a guanosine nucleotide to bind another sequence and dislodge the 5' site, then the cleavage initializes another splicing event with the remaining hydroxyl end to dislodge the rest of the RNA sequence and ligate the remaining exons. The remaining fusion protein code is different than that of the primary transcript.
Figure 4 shows a non-disruptive ligation scar and active GFP after the self-excision of IN1 and IN2. This is the modified RNA transcript prior to translation..
2.2 CONSTRUCTION MAPs AND RFC 53
As per RFC 53 convention, enzyme digestions are followed in the particular order outlined below. The standard procedure makes this technique reproducible, therefore, more easily extrapolated to other applications. Compared to other protein fusion methods, this design facilitates additional regulation within necessary guidelines. However, the embedded post-transcriptional modification in this design is a complication to consider in simpler designs where regulation at this level is not necessary. As such, unnecessary bulk in plasmid vectors is known to add to metabolic load and decrease replication rate compared to non-plasmid carriers.2.2.1 General Construction Map
Figure 5 graphically shows the laboratory procedure for the experimental design in the form of an enzyme map:
2.1.2 Controls' Construction Map
Controls are necessary to prove that the design of this experimental investigation is functional and more practically for comparison of fluorescence in the laboratory. In the positive control, GFP1 and GFP2 flank either RFC25 or RFC53, which will not disrupt translation regardless of the linker. Therefore, fluorescence is expected. The experimental run will ideally show fluorescence resulting from the self-excision of IN1 and IN2.
In the negative control using the same constitutive promoter, GFP1 and GFP2, followed by a transcriptional terminator, flank RFC10 (Request For Comments) resulting in a stop-codon-containing scar. No fluorescence is expected for this component (background) because translation is interrupted. This is meant to control for the possibility of a non functional fusion protein. The expectation is that this fusion of GFP1 and GFP2 will not fluoresce, which is a consequence of some fusion protein techniques. Figure 7 shown below details the negative control design:
The figure below shows the construction map for the controls.
2.3 MAKING THE CONSTRUCT WITH RFC 53
Figure 9 is a flow chart of the general work flow involved in the construction of our experimental plasmid, as per RFC53 conventions.
- 1) The insert is isolated through a series of enzyme digestions. One intron (in blue) is shown here as a representation. The insert is isolated for subsequent ligation.
- 2) Similarly, the pSB1C3 vector is isolated through enzyme digestion. Note that "N" indicates that this is the vector portion. The vector is also isolated for the ligation step. It must also be noted that pSB1C3 vector contains a cut site of SacI, an enzyme that is used in RFC 53. Relocating the part in BBa_K371053 resolves this issue.
- 3) The two components (insert and vector) are ligated together to produce the final construct.
- 4) According to the experimental design, the final construct will contain self-excising ribozymes, which in the last step result in a non-disruptive ligation scar and, therefore, the expression of GFP.
2.3 Preliminary Testing
Although completion of a preliminary version of the final construct was achieved, lack of GFP fluorescence proved suspicion of questionable band placements during second and third stage electrophoresis. Final diagnostic digestion reaction confirmed abnormalities from designed constructs. Testing via digestion was completed for every intermediate, control and final constructs. Consequently, BBa_K576003, K576004, K576005, and K576006 were the only parts able to be confirmed. All the other intermediates and constructs have questionable band location which disrupted final construct fluorescence.
The above electrophoresis picture describes the resultant bands from the diagnostic digestion. Although bands 5, 6 and 7 (sub clones) have been confirmed, the adjacent positive control (band 8) and all GFP and intron digestions are not consistent with the expected patterns. The GFP-INT and GFP-INT-lox constructions (bands 9, 10 and 11) have been verified as inaccurate. The questionable placements of these bands indicate that the cut sites, thus the fragment length and containing sequence, do not match the planned construction. Therefore, it is not likely that they contain functional GFP, introns or lox, which would result in a lack of fluorescence in the final stage of construction. Further testing to reconstruct the contaminated clones is necessary for the functional final product; however, lab work has stopped due to time constraint. A diagnostic digestion at each step is recommended to circumvent any similar issues upon the continuation of this project.
3.0 PRACTICAL APPLICATION
The biggest advantage of the ribozyme project is the ability to create in vivo protein fusions. These can then be applied to a larger number of modular systems that can be used to make complicated expression systems. One such system is the creation synthetic antibodies. If protein sequences are flanked by intron sequences and then set up along the same stretch of DNA, different combinations of fusion proteins will be created based on how the intron excision occurs. Another system where the ribozyme project can be applied is DNA shuffling experiments. The Cry toxin is used as an effective biopesticide, although it currently has a very small range of insects that it affects. A way to increase its range would be to change the structure of one of the vital domains so that it is able to recognize a wider spectrum of receptors in the host mid gut cell. Production of different variations of this domain and in vivo DNA shuffling experiments using the ribozymes can be carried out.
4.0 REFERENCES
Belfort,M., Cech, T., Celander, D., Chandry, P., Heuer, T. (1991). Folding of group I introns from bacteriophage T4 involves internalization of the catalytic core. Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado. 88(24): 11105–11109.
Belfort, M., Chu, F., Maley, F., Maley, G. and West, D. (1986). Characterization of the lntron in the Phage T4 Thymidylate Synthase Gene and Evidence for Its Self-Excision from the Primary Transcript. Wadsworth Center for Laboratories and Research. Vol. 45, X7-166.
Bernstein, K.E., Bunting, M., Capecchi, M.R., Greer, J.M., Thomas, K.R. (1999). Targeting genes for self-excision in the germ line.
Cassin, P., Gambier, R., Scheppler, J. (2000). Biotechnology Explorations: Applying the Fundamentals. Washington, DC: ASM Press.
Cech, T. (1990). Self-Splicing of Group I Introns. Biochemistry 59:543-8.
Clancy, S. (2008) RNA splicing: introns, exons and spliceosome. Nature Education 1(1). Genetics Primer, Fanconi Anemia Genetics. Last updated 08 February 2004. (http://members.cox.net/amgough/Fanconi-genetics-genetics-primer.htm).
Glick, B., Pasternak, J., Pattern, C. (2010). Molecular Biotechnology Principles and Applications of Recombinant DNA Fourth Edition. Washington, DC: ASM Press.
Goldberg, M., Hartwell, L., Hood, L., Reynolds, A., Silver, L., Veres, R. (2008). Genetics From Genes to Genomes Third Edition. New York: McGraw Hill Companies.
Group 1 Intron Sequence Structure and Database (http://www.rna.whu.edu.cn/gissd/alignment.html). Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado. 88(24): 11105–11109.
Ikawa, Y., Inoue, T., Ohuchi, S., Shiraishi, H. (2002). Modular engineering of Group I introns ribozyme. Graduate School of Biostudies, Kyoto University. 30(15): 3473-3480.
Landthaler, M. and Shub, D. (1999). Unexpected abundance of self-splicing introns in the genome of bacteriophage Twort: Introns in multiple genes, a single gene with three introns, and exon skipping by group I ribozymes. Microbiology Vol. 96, pp.7005–7010.
Minnick, M.F., Raghavan, R. (2009). Group I Introns and Inteins: Disparate Origins but Convergent Parasitic Strategies. Journal of Bacteriology. 191 (20), 6193-6202.
Peters Ph.D., Pamela (N/A). Restriction Enzymes Background Paper An Excellence Classic Collection. (http://www.accessexcellence.org/AE/AEC/CC/restriction.php).
Self-Splicing RNAs (http://mol-biol4masters.masters.grkraj.org/html/RNA_Processing3C-Self_Splicing_RNAs.htm). http://www.bio.davidson.edu/courses/genomics/method/CreLoxP.html
UW iGEM OUTREACH PROJECTS 2011-12
- • Worked on a variety of different projects, not all were successfull
- • Aim of UW iGEM outreach is to create a unified key message about what the team does, who we are and what is synthetic biology
- o Movie night
- o Virtual Researcher on Call (VROC) Education Podcast on synthetic biology
- o ESQ: Gr.12 activity showing how easy it is to do things from the lab at home by performing gel electrophoresis with household materials
- o BioTalks Open Panel Discussion: Bridging the gap between science and business students by holding a lecture series of key industry specialists within the Canadian Biotechnology landscape (Will add communications plan here for those interested)
- • We also compiled the following guid for creating iGEM outreach events to share our experience.
- Sign contracts with people who have made promises
- Create a budget much prior to event execution to make sure you have the resources you need and if you will have to seek extra funding
- Have a clear purpose for your event and why you are doing it, otherwise you may get lost in the planning and forget to have a crystal clear mission
- When planning a larger outreach event, it is key to have a plan before you start
- The larger the event, the more planning is required
- Create a marketing strategy, promotions strategy and most importantly a communications plan
- These formally developed plans will be key when approaching industry specialists and stakeholders within your university and externally, making them understand what exactly you want to do, your projections and what you're expecting to gain (will attach a sample of a communications snapshot from BioTalks + template on how to construct)
- Outreach is the delivery of your message, it helps others understand what you are doing and why you are doing it
- The key pillar surrounding outreach is education
- Since synthetic biology is a new advancing field within biotechnology, it is essential to deliver key messages in laymen's terms to younger generations that can be influenced into pursuing careers in science. As well, to remove stigmas and inform the public to make educated decisions
- The potential for outreach is unlimited, it is only limited by your imagination. Resources will follow if you are persistent, learn from previous failures and are passionate about the cause
- Normally outreach is pushed on the back burner, but it should be used more as a tool to attract key talent, attract sponsors and network
- Therefore it is a full-time position within a team as it requires a collaborative effort amongst internal stakeholders within your university and potential external stakeholders depending on your activities
- Design and wet lab are key, but it is difficult to excel in all components, therefore it is essential that in order to be successful in an all-rounded manner that outreach has its own position
- Using social media such as wordpress, twitter, facebook, youtube and many others can prove to be an excellent way of getting your name and cause out to the general public as well as connect with others using an interface that our generation is very familiar with no matter what their background
- It is a great way of promoting on-campus events by connecting with other accounts using that same social media platform which can exponentially increase your number of viewers with little to no cost to your team
- Hot chocolate event (Any Food Event):
- Bigger community and public, you don't just need approval of the school but of the Health and Safety Unit within the city to make sure you have everything
- Approval from the school (FEDs), not only for the event but for renting out of the space
- Make sure you are under the right hood of either a club or organization so that it will make doing events like this much more easier (e.g. we were not a FEDs club but a team). Ensure you understand the differences between them
- Making sure all the resources are available, having the equipment to make sure you have the pick up and drop off times
- Movie night/Entertainment nights
- When starting an outreach event involving entertainment for the first time turnout may not be very high but remember it is a first-time event
- Finding a space big enough to show a movie something to be considered as space is limited on campus
- Make sure you understand the process the process for equipment rentals and what exactly you'll need
- You can only show material which is licensed and the University has the rights to show.
- Make sure you set flexible dates to host your event just in case some sort of discrepancy arises
- If you plan on serving food for an event, the protocol above needs to followed again
- Show content that is relatable to your team, i.e. iGEM so you have something to talk to once you're done
- Events with Labs
- There are many courses that have labs, using the same space on different times, therefore you must find out which one you can use
- Have to accommodate for the attendees of the events and create a time for the event that would be suitable to fit within their schedules
- If it is a professor's lab that you are using, ensure that you seek approval from them much prior to the actual event (about 2 months)
- If someone within your team or outside of your team is making a commitment for the event that is critical for its execution, ensure that they either understand that once they make a commitment to a certain time they cannot leave or make them sign a contractual form binding them to the event. This will ensure no last minute cancellations
- If you're going to be using your own lab equipment, make sure you have calculated the right amount of material you will need for the projected number of attendees that will be there, along with costs and budgeting to see if you will need to charge attendees a small fee to cover the costs
- External Workshops
- Look for external attendees through your own network and the network of your team (i.e. past teachers from other schools)
- Create professional marketing material such as brochures, pamphlets and postcards (you can do this easily using Microsoft Publisher or if you know how to use Adobe Photoshop) so you can distribute materials to your prospects, making it look more professional
- Associate yourself, if possible, with a well-known organization so it will be easier to use their contacts as well as have a better brand associated with your event (i.e. for us it was for Canada's Let's Talk Science, most teachers were familiar with that organization but not with iGEM)
- If you are planning on executing an event externally, make sure you give yourself enough time to go through the effective approvals process
- If you are bringing in external attendees then make sure you have a contractual agreement with those involved (e.g. if it's a school make sure you have an agreement with the teacher of the class that is coming) so there are no last minute changes/cancellations
- Once an effective deadline is set make sure those deadlines are finalized
- Ensure that you also understand the approvals process for the external attendees far in advance so you can give yourself and your team enough time to plan (i.e. if the teacher requires approval from the principle 3 weeks in advance)
- Communication is essential
THE GUIDE TO ORGANIZING OUTREACH EVENTS
General Tips
Why Outreach is Important and Why You Should Have an Outreach Lead
Using Social Media to Promote, Promote, Promote
Motivation and Goals
This year's modelling project focused on extending the work done by the modelling team in 2010.
Waterloo's 2010 iGEM project, "Staphiscope", utilized amplifier parts developed by Cambridge in 2009 to detect low levels of Staph Aureus. These amplifier parts were characterized by the Cambridge team, but only under control of AraC/pBAD promoter, which differed from the promoter used in our 2010 Staphiscope project.
In order to characterize the amplifiers, a parameter scan was undertaken to find promoter-independent Hill parameters of each amplifier, consistent with data of full system. However, empirical verification of our results was lacking. This year, we sought to obtain this data, which (in conjunction with Cambridge data and model), would allow us to find Hill parameters for each amplifier.
Model
To allow for comparison of data, we used the same model as Cambridge in 2009.
In this model, araC represses the pBAD promoter in the absence of the inducer, arabinose. When arabinose is present, it binds to araC, preventing repression of the promoter and allowing transcription of reporter (GFP). This situation is modelled by a Hill function; we seek the Hill parameters of this function.
Thus, when AraC/pBAD system is induced with arabinose, we expect to see a steady increase of fluorescence from a low level, followed by a plateau of fluorescence at steady state.
Method
To measure fluorescence, we closely followed the assay described in the paper "Measuring the activity of BioBrick promoters using an in vivo reference standard", in the section "Assay of Promoter Collections".
Three cultures were grown overnight at 37 degrees Celsius with spinning at 200 rpm: untransformed BW27783, BW27783 containing BBa_I0500, and BW27783 containing BBa_I20260. These were then diluted 1:100 and regrown for roughly 4 hours under the same conditions. They were then diluted to an OD between 0.05 and 0.09, and regrown for 1 hour, again under the same conditions.
After this, the cultures were diluted into a 96-well plate at 8 different concentrations of inducer (arabinose), ranging from 0 to 6.4 uM. The plate was then incubated in a Wallac Victor3 multi-well fluorimeter at 37 degrees Celsius, and repeating measurements of absorbance and fluorescence were taken at 10 minute intervals, with shaking after each measurement. Untransformed BW27783, at each concentration of arabinose, was used to measure background fluorescence, and wells containing only broth were included to measure background absorbance. The machine settings used were identical to those described in the paper referenced above.
With this data, we aimed to calculate the steady-state per-cell GFP concentration during log-phase growth, for both BBa_I0500 and BBa_I20260 (measurement kit for the standard promoter, J23101). The ratio of these values would then characterize the strength of the AraC/pBAD promoter in units of RPU. The justification for this approach can be found in the supplemental material of the paper referenced above.
Results
The results of the experiment were anomalous, and considered too unreliable to be conclusive. There was no clear relationship between cell fluorescence and inducer concentration.
The fluorescence curve did not qualitatively match the predictions of the model; across all concentrations, and for each of the 3 cultures, we observed a high initial fluorescence, with a rapid drop to a lower steady state value. For each culture, this drop in fluorescence aligned well with the growth curve.
In addition, the untransformed BW27783 cells exhibited consistently higher fluorescence than cells containing BBa_I0500, which was highly anomalous. Because of this, we could not reliably use these cells to measure background fluorescence.
Below, a sample graph of Total Fluorescence is shown for each of the 3 cultures. These are curves of the total fluorescence for each culture, averaged over 3 replicates for each culture.
Discussion
It is believed that an error in our strain of BW27783 is most likely responsible for the anomalous qualitative features of our data. This is because for each concentration of inducer, the untransformed BW27783 cells exhibit a fluorescence curve highly similar to that of BW27783 containing BBa_I0500, and yet the untransformed cells should not be expressing GFP.
Prior to the measurement assay, BW27783 cells transformed with BBa_I0500 were plated and examined for fluorescence, both with and without the presence of inducer. The uninduced cells were not found to fluoresce, while the induced cells did fluoresce. The fluorescing cultures were used to make the frozen stock of BBa_I0500 which was used in the measurement assay. This indicates that our untransformed BW27783 should not fluoresce without the presence of inducer. Furthermore, the untransformed BW27783 cells used in the measurement assay were at no point prior to the assay exposed to arabinose.
To explain the fluorescence of the untransformed BW27783 in the measurement assay, it is speculated that our strain of BW27783 exhibits a rapid production of GFP in response to even low concentrations of inducer. Experimental error is also a likely source of inaccuracy in the data, although the qualitative features described were consistent across 3 trials of the experiment. Research into these results is still ongoing.
Determining The Factors Which Affect Perception of Synthetic Biology: A Multiple Regression Analysis
Despite synthetic biology's rapidly growing importance in a wide variety of fields including energy and health, it is still relatively unknown to the population at large. While some may have a vague notion of what synthetic biology is and its potential impact, most do not have anything to associate it with. In fact, some may even find the juxtaposition of artificial (synthetic) and natural (biology) confusing or contradictory. We at the iGEM University of Waterloo Human Practices team believe this represents a prime opportunity to help shape the public perception of synthetic biology and allay the fear and paranoia typically associated with the emergence of similar new fields of study. To do this effectively, we believe it's necessary to examine closely what factors or characteristics may affect a person's perception of synthetic biology. The purpose of this study, then, is to use statistical analysis, specifically regression modelling, to quantify these factors and their effect on perception. We created a survey to gather the data necessary for this analysis. It consists of three sections: first, background information to help identify the relevant factors for each respondent; next, a "pop" quiz designed to provide insight into the respondent's knowledge of synthetic biology; finally, a section that relates to the respondent's perception of synthetic biology and its uses.
The central question to be answered by this study is "what makes somebody more likely to have a favourable or unfavourable opinion of synthetic biology?" The purpose of this study is to determine the measurable effect of certain factors such as age and field of study or occupation on one's opinion of synthetic biology and its potential applications. This was to be accomplished via a regression model of the form yi = β0 + β1xi1 + β2xi2 +...+ βpxip + εi for i = 1, 2,...n,. Here y represents an individual's perception of synthetic biology, x represents each of the factors considered and β represents the corresponding quantifiable impact, positive or negative, of each factor on perception. Regression analysis was to be conducted using statistical software, most likely Stata or SPSS. The data needed for this analysis was to be collected via an online survey. Respondents will indicate the factors that correlate to them based on their answers to the questions in section #1 of the survey, while section #3 has been designed to reveal the respondent's current perception of synthetic biology. The second section of the survey is a short quiz to illustrate a respondent's level of knowledge and familiarity with synthetic biology. This factor is expected to be the major determinant in perception, along with age range and field of study/occupation. Other factors such as gender and geographic location within Ontario are expected to have no statistically significant impact on perception. The respondents were to come from a wide range of backgrounds in order to increase the robustness of our results.
The rationale behind this study is that by identifying the demographics that are most and least favourable toward synthetic biology and its expanding range of uses, the UW iGEM can more effectively target our efforts for raising awareness on the field. Despite synthetic biology's rapidly growing importance in a wide variety of fields including energy and health, it is still relatively unknown to the population at large. While some may have a vague notion of what synthetic biology is and its potential impact, most do not have anything to associate it with. In fact, some may even find the juxtaposition of artificial (synthetic) and natural (biology) confusing or contradictory. There are even organizations such as the ETC group that have published biased and one-sided reports ("Extreme Genetic Engineering: An Introduction to Synthetic Biology) that are threatening to greatly damage public opinion of synthetic biology. Biotechnology has faced a similar challenge as it has risen to prominence over the past two decades, with misinformation spread and the public lacking the fundamental knowledge necessary to critically interpret this information. In order to combat this reputation, we need to raise awareness of what synthetic biology is, along with an honest and unbiased assessment of its risks and benefits. As this can be a daunting task, the iGEM team decided to conduct this study as a way to help us focus our efforts and gain insight into the composition of perception.
After creating the survey questions, we distributed it online via Kwik Surveys using past co-op employers, campus clubs and other resources. Unfortunately we were not able to accrue enough responses to make any regression analysis statistically significant. Upon meeting with an econometrician in mid-September, we decided to refocus the survey on revealing the mechanism by which some groups end up with specific misconceptions regarding synthetic biology. As an (albeit very exaggerated) example, if the survey were to reveal that respondents with children were much more likely to support the notion that synthetic biology was "playing God by creating life," one might speculate that these respondents feel that as parents only they have exclusive domain of creating life. The value of this past year's project was to gain experience in the areas of survey creation and distribution, as well as to build connections with those who can help take next year's Human Practices to new levels.
TEST TEST page
OUR TEAM!
Linda Yang - Assistant Director
Ekta Bibra - Outreach Leader
Anjali Arya - Outreach Leader
Angela Biskupovic - Human Practice Leader
Simon Burru - Human Practices Leader
Aaron Bender - Lab Project Leader
Dongbin Zhang - Lab Project Leader
Denise Lieuson - Lab Project Leader
Rummy Chowdhury - Lab Project Leader
OUR ADVISORS!
UNIVERSITY OF WATERLOO
University of Waterloo was founded in 1957 and has grown to accommodate 30,000 undergraduate and graduate students, and has become Canada's leading university in comprehensive learning. Also, the university has consistently been voted as the most innovative, most likely to produce the leaders of tomorrow, and best overall University in Canada for over 18 years (according to Maclean's Magazine). Waterloo's reputation is however based on its excellent and pioneering co-op program which offers students a balance of work and school on a per term basis, making it a unique learning experience. The city of Waterloo has recognized University of Waterloo and its students, by meeting its demands in terms of funding and involvement. The University has also opened up two new campuses; the pharmacy building, and the joint McMaster medical building in Kitchener, as well as the architecture building in Cambridge, contributing to not only the city of waterloo but the whole Grand River area.
WATERLOO - KITCHENER COMMUNITY
City of Waterloo mainly revolves around the two universities: University of Waterloo and Laurier University. Waterloo is surrounded by Kitchener and thus, the two cities are known as the twin cities, also referred to as Kitchener - Waterloo. The population of the city of Waterloo is always fluctuating due to temporary residents at Waterloo's two universities. Total population in 2009 was recorded to be 121, 700; approximately 20,000 of which were temporary post-secondary students. Due to its small size, people in the past have tried to merge the two cities together but have been unsuccessful. As of today, both cities have their own identity and their own separate city governments.
UW's parts for 2012
BBa_K576003 - RNA - Left part of self-excising ribozyme
BBa_K576004 - RNA - Right part of self-excising ribozyme
BBa_K576005 - Reporter - Left part of GFP (GFP 1) with promoter (J23101) and RBS (B0034)
BBa_K576006 - Reporter - Right part of GFP (GFP 2) with transcription terminator
BBa_K576007 - Intermediate - Left part of GFP with left part of self-excising ribozyme attached using RFC 53 construction.
BBa_K576008 - Intermediate - Right part of the self-excising ribozyme attached to the right part of GFP using RFC 53 construction
BBa_K576009 - Intermediate - Lox attached on to BBa_K576005 on the right of the part. Standard assembly (RFC 10) was used for this construction.
BBa_K576010 - Intermediate - Lox attached on to BBa_K576008 on the left of the part. BBa_K576009 or BBa_K576010 can be used depending on your convenience
BBa_K576011 - Reporter - Final construction of the 2011 project. The self-excising ribozyme should be cut out of from the rest of the sequence and thus expressing the full GFP.
BBa_K576012 - Reporter - Negative control of the experiment. The lox recombination site interrupts the GFP expression
BBa_K576013 - Reporter - Positive control of the experiment. Everything in between has been cut out by the self-excising intron and the GFP is fully expressed.
The UW 2012 lab project is a continuation from the 2011 one, thus no new parts are introduced.
Lab Notebook 2011
The following entries pertain to the Quantification Project
Tuesday, May 31, 2011
Wednesday, June 1, 20111
Thursday, June 2, 20111
Friday, June 3, 20111
Monday, June 6, 20111
Tuesday, June 7, 20111
Wednesday June 8, 20111
Thursday June 9, 20111
Friday June 10, 20111
Tuesday, June 14, 20111
Thursday, June 16, 20111
Monday, June 20, 20111
Tuesday, June 21, 20111
Wednesday, June 22, 2011
Thursday, June 23, 2011
Friday, June 24, 2011
Monday, July 4, 2011
Tuesday, July 5, 2011
Monday, July 11, 2011
Tuesday, July 12, 2011
Wednesday, July 13, 2011
Thursday, July 14, 2011
The following entries pertain to the Ribozyme Project
Wednesday July 6, 2011
Thursday July 7, 2011
Friday July 8, 2011
Sequences | In1 | In2 | GFP 2 | pSB1C3 |
260/280 | 1.85 | 1.80 | 1.88 | 1.86 |
ng/ul | 229.8 | 236.1 | 198.6 | 166.2 |
Tuesday July 12, 2011
Wednesday July 13, 2011
Thursday July 14, 2011
Friday July 15, 2011
Monday July 18, 2011
Tuesday July 19, 2011
Wednesday July 20, 2011
Thursday July 21, 2011
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Monday July 25, 2011
Tuesday July 26, 2011.
Wednesday July 27, 2011
July 30, 2011
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Septermber 8th, 2011
Septermber 9th – 15th, 2011
September 16th, 2011
SAFETY
Laboratory Safety
The Ribozyme Project is not expected to raise any research, public or environmental safety concerns other than those normally associated with Biosafety Level 2 organisms, such as Escherichia coli (DH5-alpha), which is classified as very low to moderate. The use of this project is primarily reserved for research and laboratory use, therefore, should not purposefully be exposed to the public or environment except after further testing in its specific applications (such as with particular fusion proteins). Furthermore, the basis of our project is to establish a self-excising sequence (ribozymes), which should limit the expression of any intervening sequences to the RNA level. If the intervening sequence were something of environmental or public relevance (such as antibiotic resistance), the experimental design indicates that the sequence will be removed and, thus, not expressed. This is a relevant contribution of the design in limiting expression to the RNA level, which eases environmental hazard concern upon the accidental release of a GMO containing this biobrick. Therefore, the new biobrick parts submitted should not raise any safety issues.The necessary facility, equipment and handling procedures associated with Level 2 Biosafety concerns were met:
1.Pipetting aids
2.Biosafety cabinets where applicable
3.Laboratory separated from other activities
4.Biohazard sign
5.Proper safety and disposal equipment, including autoclave
6.Personal protective equipment, worn only in the laboratory
7.Screw-capped tubes and bottles
8.Plastic disposable pasteur pipettes, when necessary
All precautions with respect to recombinant DNA were observed:
1.All waste was autoclaved before being thrown away.
2.Researchers practiced aseptic technique and personal hygiene and safety precautions
3.Procedures likely to generate aerosols are performed in a biosafety cabinet
4.Bench surfaces were disinfected with ethanol.
4.Potentially contaminated waste is separated from general waste
Safety Questions
1. Would the materials used in your project and/or your final product pose: The materials used in the lab are non toxic to health of individuals as well as to the environment. One of the major reagents that is used is GelRed which is used as a substitute for Ethidium Bromide. Gel Red is unable to penetrate into cells and so is a non-mutagenic agent. As well it has the same spectral characteristics as Ethidium Bromide and so has the same effectiveness of use. The project itself is safe even if released into the environment by design or accident since the part being expressed is the Green Fluorescent Protein (GFP). Unless the sequences are mutated, the project poses no risk.
Please explain your responses (whether yes or no) to these questions.
Specifically, are any parts or devices in your project associated with (or known to cause):
- pathogenicity, infectivity, or toxicity? No
- threats to environmental quality? No
- security concerns? No
The parts that are associated with the project this year are at the same level of risk as the any of the regular parts that already exist. All parts are constructed in an antibiotic containing backbone so that accidental release of will pose minimal risk to contaminating other bacterial populations.
2.Under what biosafety provisions will / do you operate?
a.Does your institution have its own biosafety rules and if so what are they? The University of Waterloo had a Bio-Safety plan in place to ensure the proper use to bio-hazardous materials in teaching and research at the university. A more detailed overview of their plans is outlined at the Bio-Safety Website
b. Does your institution have an Institutional Biosafety Committee or equivalent group? If yes, have you discussed your project with them? The laboratories operating at the University of Waterloo have obtained permits from the Bio-Safety Committee in order to perform intended research. Since the Waterloo iGEM team performs all laboratory work in a parent lab under the guidance of the Masters and PhD students of that lab, the projects carried out in the lab are covered by the permits obtained by the parent lab.
c. Will / did you receive any biosafety and/or lab training before beginning your project? If so, describe this training. All lab volunteers are required to take an online training to familiarize themselves with the Biosafety practices of the University of Waterloo. The training is followed up by a quiz ensuring proper understanding of the material. Upon completion of the training and quiz a hands- on lab training is provided under supervision of the parent lab's PhD student. The hands-on training involves instruction of use of the appropriate equipment that is used in the lab, as well as how to maintain and discard materials in a safe manner.
d. Does your country have national biosafety regulations or guidelines? If so, provide a link to them online if possible. Canada operates under the guidelines set up by the Public Health Agency of Canada. The Agency is the national authority on matters concerning biosafety and biosecurity. Risks to the public are reduced by standardizing controls over activities that involve human pathogenic agents, domestic or imported. While these guidelines are in place the current iGEM project does not involve work with any agents or materials that may pose a risk to humans. The link to the Public Health Agency of Canada is provided below: Public Health Agency of Canada