Difference between revisions of "Team:BostonU/Description"

 
(58 intermediate revisions by 3 users not shown)
Line 19: Line 19:
 
}
 
}
  
#media {
 
background-color:white;
 
}
 
 
#twit, #face, #snap, #email {
 
width:100px;
 
height:100px;
 
padding: 30px;
 
}
 
 
#twit:hover, #face:hover, #snap:hover, #email:hover {
 
height:150px;
 
width:150px;
 
padding: 30px;
 
}
 
 
p{text-indent:70px;}
 
 
#button {
 
background-color:blue;
 
width:10vh;
 
height:10vh;
 
position:fixed;
 
margin:20vh 0vh 0vh 0vh;
 
}
 
  
 
</style>
 
</style>
Line 49: Line 24:
 
<body>
 
<body>
  
<div id = "button"></div>
+
<div style = "width:100%; margin:0 auto;">
 
+
<div style = "width:80%; margin:0 auto;">
+
 
<center>
 
<center>
 
<div>
 
<div>
<div style = "font-size:300%; padding:75px 50px 25px 50px; text-align:center; color:#0071A7;">Description</div>
+
<div style = "font-size:300%; padding:75px 50px 3px 50px; text-align:center; color:#0071A7;">Improved Part Characterization</div>
  
 
<br><center><hr style= "width:60%; height: 3px; background-color:#0071A7"></center><br>
 
<br><center><hr style= "width:60%; height: 3px; background-color:#0071A7"></center><br>
  
<p style = "font-size:150%; padding:25px 150px 50px 150px; color:#0071A7;">Our project aims to integrate multiple digital environmental signals (signals that are either present or absent, no in between) to dictate the analog expression level of a certain gene. Different combinations of these digital signals will produce different intensities of gene expression. This is similar to many gene activation pathways found in nature, and yet there is no standardized, easy-to-use system to replicate these pathways. Being able to dynamically change the level of gene expression based on combinations of multiple environmental signals would be invaluable to creating responsive, dynamic genetic devices. Therefore, our goal this summer is to create a system that can recognize multiple digital signals, and change the level of gene expression based on what combination of signals it is registering. This system would work with any gene of interest, allowing it to be used in diverse applications including immune therapy, recreating natural genetic signaling pathways, and research of toxic genes. Scroll down to see how we designed our system to meet these aims.</p>
+
<p style = "font-size:150%; padding:5px 150px 15px 150px; color:#0071A7;">Our team worked to improve the characterization of a <a href = "http://parts.igem.org/Part:BBa_I712004" style = "color:blue;"> CMV promoter, BBa_I712004</a>, part from the iGEM Registry. This part originated from the Heidelberg 2009 iGEM team as a “constitutive” promoter that could be expressed in HeLa mammalian cells. The cytomegalovirus (CMV) promoter is commonly used for gene expression in mammalian cells.</p>
<br><br><br>
+
  
<div id = "design" style = "font-size:300%; padding:75px 50px 25px 50px; text-align:center; color:#0071A7;">Design</div>
+
<p style = "font-size:150%; padding:5px 150px 15px 150px; color:#0071A7;">
 +
As part of our characterization, this part was also directly compared to several of our Gemini library plasmids, more specifically:  <a href = "http://parts.igem.org/Part:BBa_K1875014" style = "color:blue;">BBa_K1875014</a>, <a href = "http://parts.igem.org/Part:BBa_K1875015" style = "color:blue;">BBa_K1875015</a>, <a href = "http://parts.igem.org/Part:BBa_K1875016" style = "color:blue;">BBa_K1875016</a> and <a href = "http://parts.igem.org/Part:BBa_K1875018" style = "color:blue;">BBa_K1875018</a>. These new parts were co-transfected into HEK293FT cells with a dCas9-VPR expression vector and the corresponding gRNA expression vectors, and then assayed using flow cytometry. We measured fluorescence of the CMV promoter device relative to these devices.</p>
  
<br><center><hr style= "width:60%; height: 3px; background-color:#0071A7"></center><br>
+
<p style = "font-size:150%; padding:5px 150px 15px 150px; color:#0071A7;">  
 +
Parts BBa_K1875014, BBa_K1875015, and BBa_K1875016 correspond to three of our single operator promoters driving GFP.  In addition to these we compared the CMV to three of our Gemini library plasmids with three multimerized operator sites upstream of a minimal promoter driving GFP, one of which was submitted to the iGEM registry under the code BBa_K1875018.  Flow cytometry found that five of the six Gemini parts we compared to the CMV fluoresced anywhere between half as bright to five times as bright as the CMV.</p>
  
<br><br><center style = "font-size:225%; color:#0071A7;">Phase 1:</center><br>
+
<p style = "font-size:150%; padding:5px 150px 15px 150px; color:#0071A7;">
<center style = "font-size:200%; color:#0071A7;">Gene Activation Component</center>
+
The experimental procedures used in this assay involved measuring fluorescence using Mean Fluorescence Intensity (M.F.I.). Thus, the absolute values are arbitrary units, and cannot be directly compared to other expression systems unless re-tested in the same context. Our experiment, however, does reveal the relative strength of the CMV promoter device as compared to both of our well-characterized parts.</p>
  
<p style = "font-size:150%; padding:25px 150px 20px 150px; color:#0071A7;">In order to make genes activate in response to certain signals, our system first needed a method to activate genes in general. We chose CRISPR/dCAS9-VPR as an activator. We chose  dCAS9 due to its ease of use and its ability to target specific DNA sequences. dCAS9-VPR targets specific sequences by binding to specialized RNA. Part of this RNA (gRNA) contains 20 base pairs that will act as a guide, guiding the dCAS9 to the complimentary 20 base pairs found upstream of a gene one wishes target. This can be seen in the info-graphic below:</p>
+
<center><img src = "https://static.igem.org/mediawiki/2016/7/7a/T--BostonU--Bba_I712004_Validation.png" style = "padding:5px 150px 15px 150px; width:50%;"></center>
  
 +
<p style = "font-size:150%; padding:5px 150px 15px 150px; color:#0071A7;">BBa_I712004 compared to two Gemini operator promoter plasmids containing the same gRNA operator.  The CMV fluoresced twice as bright as the single operator promoter plasmid BBa_K1875016 (denoted by the singular operator site) and about a fourth as bright as the triple operator promoter plasmid (denoted by the triple operator site).</p>
  
<center><img src = "https://static.igem.org/mediawiki/2016/3/37/T--BostonU--ProjectDescription_dCas9_explanation.png" style = "padding:0px 0px 50px 0px; width:80%;"></center>
+
<center><img src = "https://static.igem.org/mediawiki/2016/1/10/T--BostonU--Bba_I712004_Validation_Part2.png" style = "padding:5px 150px 15px 150px; width:50%;"></center>
  
<br><br><br><center style = "font-size:225%; color:#0071A7;">Phase 2:</center><br>
+
<p style = "font-size:150%; padding:5px 150px 15px 150px; color:#0071A7;">
<center style = "font-size:200%; color:#0071A7;">Analog Expression System</center>
+
CMV compared to three Gemini single operator promoters (BBa_K1875014, BBa_K1875015, and BBa_K1875016 respectively).  The CMV expressed GFP at a greater intensity than all of the single operator promoters with the sole exception of the promoter containing the g3 operator.</p>
  
<p style = "font-size:150%; padding:25px 150px 20px 150px; color:#0071A7;">Once we were able to activate genes, we then expanded our system to activate genes to different levels, thereby achieving the graded analog expression level that we desired from our system. To accomplish this, we multermerized the 20 base pair target sequence, placing multiple copies
+
<center><img src = "https://static.igem.org/mediawiki/2016/8/88/T--BostonU--Bba_I712004_Validation_Part3.png" style = "padding:5px 150px 15px 150px; width:50%;"></center>
of the target sequence upstream of the gene. By varying the number of copies, we were able to create a gradient of expression. The more target sequences we added, the more the gene was activated. This is illustrated in the image below:</p>
+
  
<center><img src = "https://static.igem.org/mediawiki/2016/d/d9/T--BostonU--multimerization.png" style = "padding:0px 0px 50px 0px;; width:80%;"></center>
 
  
<br><br><br><center style = "font-size:225%; color:#0071A7;">Phase 3:</center><br>
+
<p style = "font-size:150%; padding:5px 150px 15px 150px; color:#0071A7;">BBa_I712004 compared to four triple operator promoters.  The CMV fluoresced anywhere between a third to a fifth as brightly as the four triple operator promoters. We submitted the operator promoter containing g13 to the iGEM registry, under the name BBa_K1875018.</p>
<center style = "font-size:200%; color:#0071A7;">Signal Integration Components</center>
+
  
<p style = "font-size:150%; padding:25px 150px 20px 150px; color:#0071A7;">Finally, once we completed phase one and two, we expanded our system once again. Using recombinase based circuits, we were able to control which gRNA was produced. gRNA 1 corresponded to a reporter with one target sequence, and gRNA 2 corresponded to the same gene but with two of the target sequence. Releasing gRNA 1 turned the gene on to a small degree, and gRNA two turned it on to a large degree. We then incorporated two more gRNA's flanked by two more recombinase recognition sites, allowing the system to have a smoother, four point analog expression level increase. Since the recombinase circuits that release the different gRNA is completely digital, (the recombinases are activated by the digital prescience or absence of a signal such as a hormone and once activated, are extremely efficient) the system was a merger of digital signals giving rise to different levels of analog gene expression, as stated in our goal. A diagram of these circuits can be found below:</p>
+
<br><br><br>
 
+
<center><img src = "https://static.igem.org/mediawiki/2016/0/06/T--BostonU--RealRecombinase.png" style = "padding:0px 0px 50px 0px;; width:80%;"></center>
+
</div>
+
</div>
+
</center>
+
</div>
+
  
 
</body>
 
</body>
 
</html>
 
</html>

Latest revision as of 22:25, 19 October 2016

Improved Part Characterization



Our team worked to improve the characterization of a CMV promoter, BBa_I712004, part from the iGEM Registry. This part originated from the Heidelberg 2009 iGEM team as a “constitutive” promoter that could be expressed in HeLa mammalian cells. The cytomegalovirus (CMV) promoter is commonly used for gene expression in mammalian cells.

As part of our characterization, this part was also directly compared to several of our Gemini library plasmids, more specifically: BBa_K1875014, BBa_K1875015, BBa_K1875016 and BBa_K1875018. These new parts were co-transfected into HEK293FT cells with a dCas9-VPR expression vector and the corresponding gRNA expression vectors, and then assayed using flow cytometry. We measured fluorescence of the CMV promoter device relative to these devices.

Parts BBa_K1875014, BBa_K1875015, and BBa_K1875016 correspond to three of our single operator promoters driving GFP. In addition to these we compared the CMV to three of our Gemini library plasmids with three multimerized operator sites upstream of a minimal promoter driving GFP, one of which was submitted to the iGEM registry under the code BBa_K1875018. Flow cytometry found that five of the six Gemini parts we compared to the CMV fluoresced anywhere between half as bright to five times as bright as the CMV.

The experimental procedures used in this assay involved measuring fluorescence using Mean Fluorescence Intensity (M.F.I.). Thus, the absolute values are arbitrary units, and cannot be directly compared to other expression systems unless re-tested in the same context. Our experiment, however, does reveal the relative strength of the CMV promoter device as compared to both of our well-characterized parts.

BBa_I712004 compared to two Gemini operator promoter plasmids containing the same gRNA operator. The CMV fluoresced twice as bright as the single operator promoter plasmid BBa_K1875016 (denoted by the singular operator site) and about a fourth as bright as the triple operator promoter plasmid (denoted by the triple operator site).

CMV compared to three Gemini single operator promoters (BBa_K1875014, BBa_K1875015, and BBa_K1875016 respectively). The CMV expressed GFP at a greater intensity than all of the single operator promoters with the sole exception of the promoter containing the g3 operator.

BBa_I712004 compared to four triple operator promoters. The CMV fluoresced anywhere between a third to a fifth as brightly as the four triple operator promoters. We submitted the operator promoter containing g13 to the iGEM registry, under the name BBa_K1875018.