Team:TUDelft/Temperature conclusions

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(Temperature sensitivity - Results with sonication)
 
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=Conclusions & Recommendations=
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=Conclusions Temperature=
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==Conclusions==
 
After a great summer of hard work, we've learned quite a few things. The most important about the thermometer RNA are listed below.  
After a great summer of hard work, we've learned quite a few things. The most important about the thermometer RNA are listed below.  
===Temperature sensitivity - Protein measurements===
===Temperature sensitivity - Protein measurements===
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Due to the fact it is impossible to state that lysis has a constant efficiency, it is not possible to take the cell density before lysis as a value for correcting luciferase activity. Therefore it is important to measure something in the soluble fraction of your sample correlating to actual biomass . We decided to use a total protein content (Bicinchoninic acid assay) for the value to correct luciferase activity by. However, the lysis buffer (of unknown composition) in the luciferase assay kit interfered with our protein measurements. To prevent this interference we tried precipitating the protein in the samples using 4 different methods to get rid of the (unknown) interfering agent in the buffer. Although calibration curves which were first treated with lysis buffer and then precipitated varied from quite linear (R<sup>2</sup>=0.983) to not linear at all (R<sup>2</sup><0), samples containing the soluble fraction of lysed cells, usually gave protein contents of below 0 mg/ml.
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Because lysis efficiency seems to vary during and in between experiments, it is not possible to take the cell density before lysis as a value for correcting luciferase activity. Protein content measurements of the soluble fraction after lysis should be conducted to reliably normalize luminescence. Total protein content determination was performed by Bicinchoninic acid assay (BC assay). However, the lysis buffer (of unknown composition) in the luciferase assay kit interfered with the protein measurements. To circumvent this interference we tried precipitating the protein in the samples using 4 different methods to get rid of the (unknown) interfering agent in the lysis buffer. Although calibration curves that were first treated with lysis buffer and then precipitated varied from quite linear (R<sup>2</sup>=0.983) to not linear at all (R<sup>2</sup><0), samples containing the soluble fraction of lysed cells usually gave protein contents of below 0 mg/ml.
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A different approach to solve this problem of lysis buffer interference was trying various different lysis methods, including sonication, using glass beads in a fastprep or using lysozyme and glass sand in a bead beater. Although it looked like all these methods destroy some of the activity of luciferase in the sample, time was lacking to optimize each method. The sonication protocol, although time consuming, seemed most reliable in our experiments. Still, this method is not optimal, as samples lysed with lysis buffer show a lot higher raw luciferase output, although it is not known what the total protein content of these samples is.
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A different approach to solve the problem of lysis buffer interference was trying different lysis methods. Sonication, using glass beads in a FastPrep or using lysozyme and glass sand in a bead beater. Some luciferase activity was lost with all these methods, and time was lacking to optimize each method. The sonication protocol, although time consuming, seemed most reliable in our experiments. Still, this method is not optimal, as samples lysed with lysis buffer show a lot higher raw luciferase output.
===Temperature sensitivity - Results with sonication===
===Temperature sensitivity - Results with sonication===
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Using sonication of our samples, we obtained our most reliable results. These indicated, as displayed [https://2008.igem.org/Image:TUDelft221508a.png here], that our strain K115035 shows the temperature induced switch-like behavior which was the aim of our project.  
+
Using sonication of our samples, we obtained the most reliable results. These indicated, as displayed [https://2008.igem.org/Image:TUDelft221508a.png here], that our strain K115035 shows the temperature induced switch-like behavior which was the aim of our project.  
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Latest revision as of 17:45, 29 October 2008

Conclusions Temperature

After a great summer of hard work, we've learned quite a few things. The most important about the thermometer RNA are listed below.

Temperature sensitivity - Protein measurements

Because lysis efficiency seems to vary during and in between experiments, it is not possible to take the cell density before lysis as a value for correcting luciferase activity. Protein content measurements of the soluble fraction after lysis should be conducted to reliably normalize luminescence. Total protein content determination was performed by Bicinchoninic acid assay (BC assay). However, the lysis buffer (of unknown composition) in the luciferase assay kit interfered with the protein measurements. To circumvent this interference we tried precipitating the protein in the samples using 4 different methods to get rid of the (unknown) interfering agent in the lysis buffer. Although calibration curves that were first treated with lysis buffer and then precipitated varied from quite linear (R2=0.983) to not linear at all (R2<0), samples containing the soluble fraction of lysed cells usually gave protein contents of below 0 mg/ml.

A different approach to solve the problem of lysis buffer interference was trying different lysis methods. Sonication, using glass beads in a FastPrep or using lysozyme and glass sand in a bead beater. Some luciferase activity was lost with all these methods, and time was lacking to optimize each method. The sonication protocol, although time consuming, seemed most reliable in our experiments. Still, this method is not optimal, as samples lysed with lysis buffer show a lot higher raw luciferase output.

Temperature sensitivity - Results with sonication

Using sonication of our samples, we obtained the most reliable results. These indicated, as displayed here, that our strain K115035 shows the temperature induced switch-like behavior which was the aim of our project.