Difference between revisions of "Team:NKU CHINA/interlab"

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</head>
  
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<div id="ilhead">Interlab</div>
 
<div id="ilhead">Interlab</div>
  
 +
 +
<h1>InterLab</h1>
 +
<h3>Overview</h3>
 +
<p>Poverty in taking reliable and repeatable measurements remains a key obstacle in establishing synthetic biology as an engineering discipline. The Measurement Committee has been studying the measurement procedure for green fluorescent protein (GFP) over the last several years by interlab. The most commonly used markers though GFP is in synthetic biology, labs often resort to making relative comparisons, which makes it difficult for labs to share and data and/or constructs.<br><br>
 +
The goal of the fifth iGEM InterLab Study is to identify and correct the sources of systematic variability in synthetic biology measurements by answering the question "Can we reduce lab-to-lab variability in fluorescence measurements by normalizing to absolute cell count or colony-forming units (CFUs) instead of OD? "<br><br>
 +
As we know in the previous study, the fluorescence value measured by a plate reader is an aggregate measurement of an entire population of cells, we need to divide the total fluorescence by the number of cells in order to determine the mean expression level of GFP per cell. Due to the fact that the "optical density (OD)" of the sample is an approximation of the number of cells varying from lab to lab, we decided to use a special silica beads that are roughly the same size and shape as a typical E. coli cell to set up a universal, standard "equivalent concentration of beads" measurement.
 +
</p>
 +
  <div id="Navigation">
 +
  <h3 id="materials">Materials</h3>
 +
      <div class="menu">
 +
        <span>Reagents and Apparatus</span>
 +
        <a href="#"><ul>
 +
<li>Competent cells (Escherichia coli strain DH5α)</li>
 +
<li>1ml LUDOX CL-X (provided in kit) </li>
 +
<li>300 μL Silica beads - Microsphere suspension (provided in kit, 4.7 x 10^8 microspheres)</li>
 +
<li>LB (Luria Bertani) media</li>
 +
<li>Fluorescein (provided in kit) </li>
 +
<li>10ml 1xPBS pH 7.4-7.6 (phosphate buffered saline; provided by team) </li>
 +
<li>Chloramphenicol (stock concentration 25 mg/mL dissolved in EtOH) </li>
 +
<li>50 ml Falcon tube (or equivalent, preferably amber or covered in foil to block light) </li>
 +
<li>Incubator at 37°C</li>
 +
<li>1.5 ml eppendorf tubes for sample storage</li>
 +
<li>Ice bucket with ice</li>
 +
<li>Micropipettes and tips</li>
 +
<li>96 well plate, black with clear flat bottom preferred (provided by team)</li>
 +
</ul>
 +
</a>
 +
      </div>
 +
      <div class="seperator"></div>
 +
      <div class="menu2">
 +
        <span>Devices</span>
 +
        <a href="#">
 +
        <h4>From Distribution Kit, all in pSB1C3 backbone:</h4>
 +
        <ul>
 +
<li>Negative control BBa_R0040</li>
 +
<li>Positive control BBa_I20270</li>
 +
<li>Test Device 1 BBa_J364000</li>
 +
<li>Test Device 2 BBa_J364001</li>
 +
<li>Test Device 3 BBa_J364002</li>
 +
<li>Test Device 4 BBa_J364007</li>
 +
<li>Test Device 5 BBa_J364008</li>
 +
<li>Test Device 6 BBa_J364009</li>
 +
</ul>
 +
        </a>
 +
      </div>
 +
    <h3 id="methods">Methods</h3>
 +
     
 +
      <div class="menu3">
 +
        <span>OD 600 Reference Point</span>
 +
        <a href="#"><ul>
 +
<li>Add 100μl LUDOX into wells A1, B1, C1, D1</li>
 +
<li>Add 100μl of dd H2O into wells A2, B2, C2, D2</li> 
 +
<li>Measure absorbance at 600 nm of all samples in the measurement mode you plan to use for cell measurements</li>
 +
<li>Record the data in the table below or in your notebook</li>
 +
<li>Import data into Excel sheet provided (OD600 reference point tab)</li>
 +
</ul>
 +
</a>
 +
      </div>
 +
      <div class="seperator"></div>
 +
      <div class="menu4">
 +
      <span>Particle Standard Curve</span>
 +
      <a href="#"><ul>
 +
<li>Obtain the tube labeled "Silica Beads" from the InterLab test kit and vortex vigorously for 30 seconds</li>
 +
<li>Immediately pipet 96 μL microspheres into a 1.5 mL eppendorf tube</li>
 +
<li>Add 904μL of ddH2O to the microspheres</li>
 +
<li>Vortex well. This is your Microsphere Stock Solution</li>
 +
<li>Repeat dilution series for rows B, C, D</li>
 +
<li>Re-Mix (Pipette up and down) each row of plate immediately before putting in the plate reader</li>
 +
<li>Measure Abs600 of all samples in instrument</li>
 +
<li>Record the data in your notebook</li>
 +
<li>Import data into Excel sheet provided (particle standard curve tab)</li>
 +
</ul>
 +
      </a>
 +
      </div>
 +
      <div class="seperator"></div>
 +
      <div class="menu5">
 +
      <span>Fluorescence Standard Curve </span>
 +
      <a href="#"><ul>
 +
<li>Spin down fluorescein kit tube to make sure pellet is at the bottom of tube. </li>
 +
<li>Prepare 10x fluorescein stock solution (100 μM) by resuspending fluorescein in 1mL of 1xPBS</li>
 +
<li>Dilute the 10x fluorescein stock solution with 1xPBS to make a 1x fluorescein solution with concentration 10 μM: 100 μL of 10x fluorescein stock into 900 μL 1xPBS</li>
 +
<li>Add 100 μl of PBS into wells A2, B2, C2, D2...A12, B12, C12, D12</li>
 +
<li>Add 200 μl of fluorescein 1x stock solution into A1, B1, C1, D1</li>
 +
<li>Transfer 100 μl of fluorescein stock solution from A1 into A2</li>
 +
<li>Mix A2 by pipetting up and down 3x and transfer 100 μl into A3…</li>
 +
<li>Mix A3 by pipetting up and down 3x and transfer 100 μl into A4...</li>
 +
<li>Mix A4 by pipetting up and down 3x and transfer 100 μl into A5...</li>
 +
<li>Mix A5 by pipetting up and down 3x and transfer 100 μl into A6...</li>
 +
<li>Mix A6 by pipetting up and down 3x and transfer 100 μl into A7...</li>
 +
<li>Mix A7 by pipetting up and down 3x and transfer 100 μl into A8...</li>
 +
<li>Mix A8 by pipetting up and down 3x and transfer 100 μl into A9...</li>
 +
<li>Mix A9 by pipetting up and down 3x and transfer 100 μl into A10...</li>
 +
<li>Mix A10 by pipetting up and down 3x and transfer 100 μl into A11...</li>
 +
<li>Mix A11 by pipetting up and down 3x and transfer 100 μl into liquid waste</li>
 +
<li>Repeat dilution series for rows B, C, D</li>
 +
<li>Measure fluorescence of all samples in instrument</li>
 +
<li>Record the data in your notebook</li>
 +
<li>Import data into Excel sheet provided (fluorescein standard curve tab)</li>
 +
</ul>
 +
</a>
 +
</div>
 +
<div class="seperator"></div>
 +
    <div class="menu6">
 +
      <span>Competent Cells and Transformation</span>
 +
      <a href="#"><ul>
 +
<li>Resuspend DNA in selected wells in the Distribution Kit with 10µl dH<sub>2</sub>O</li>
 +
<li>Thaw competent cells on ice</li>
 +
<li>Pipette 50µl of competent cells into 1.5ml tube</li>
 +
<li>Pipette 1µl of resuspended DNA into 1.5ml tube</li>
 +
<li>Pipette 1µl of control DNA into 2ml tube</li>
 +
<li>Close 1.5ml tubes, incubate on ice for 30min</li>
 +
<li>Heat shock tubes at 42°C for 45 sec</li>
 +
<li>Incubate on ice for 5min</li>
 +
<li>Pipette 950µl SOC media to each transformation</li>
 +
<li>Incubate at 37°C for 1 hours, shaking at 200-300rpm</li>
 +
<li>Pipette 100µL of each transformation onto petri plates</li>
 +
<li>Spin down cells at 6800g for 3mins and discard 800µL of the supernatant. Resuspend the cells in the remaining 100µL, and pipette each transformation onto petri plates</li>
 +
<li>Incubate transformations overnight (14-18hr) at 37°C</li>
 +
<li>Pick single colonies for PCR</li>
 +
<li>Count colonies for control transformation</li>
 +
</ul>
 +
</a>
 +
</div>
 +
<div class="seperator"></div>
 +
      <div class="menu7">
 +
      <span>Cell Measurement</span>
 +
      <a href="#"><ul>
 +
<li>Pick 2 colonies from each of the transformation plates and inoculate in 5-10 mL LB medium + Chloramphenicol. Grow the cells overnight (16-18 hours) at 37°C and 220 rpm</li>
 +
<li>Make a 1:10 dilution of each overnight culture in LB + Chloramphenicol (0.5mL of culture into 4.5mL of LB + Chlor)</li>
 +
<li>Measure Abs 600 of these 1:10 diluted cultures</li>
 +
<li>Record the data in your notebook</li>
 +
<li>Dilute the cultures further to a target Abs600 of 0.02 in a final volume of 12 ml LB medium + Chloramphenicol in 50 mL falcon tube (amber, or covered with foil to block light)</li>
 +
<li>Take 500 µL samples of the diluted cultures at 0 hours into 1.5 ml Eppendorf tubes, prior to incubation. (At each time point 0 hours and 6 hours, you will take a sample from each of the 8 devices, two colonies per device, for a total of 16 Eppendorf tubes with 500 µL samples per time point, 32 samples total). Place the samples on ice</li>
 +
<li>Incubate the remainder of the cultures at 37°C and 220 rpm for 6 hours</li>
 +
<li>Take 500 µL samples of the cultures at 6 hours of incubation into 1.5 ml Eppendorf tubes. Place samples on ice</li>
 +
<li>At the end of sampling point you need to measure your samples (Abs 600 and fluorescence measurement), see the below for details</li>
 +
<li>Record data in your notebook</li>
 +
<li>Import data into Excel sheet provided (fluorescence measurement tab)</li>
 +
</ul>
 +
</a>
 +
</div>
 +
<div class="seperator"></div>
 +
      <div class="menu8">
 +
      <span>CFU per 0.1 OD600 E.coli Cultures</span>
 +
      <a href="#"><ul>
 +
</li>Culture colonies for two Positive Control (BBa_I20270) cultures and your two Negative Control (BBa_R0040) cultures for 16-18 hours</li>
 +
<li>Dilute the overnight culture to OD600 = 0.1 in 1mL of LB + Cam media. Do this in triplicate for each culture. Check the OD600 and make sure it is 0.1</li>
 +
<li>Aseptically spead plate 100 μL on LB + Cam plates for those Final Dilution Factor is 8 x 10<sup>4</sup> or 8 x 10<sup>5</sup> or 8 x 10<sup>6</sup></li>
 +
<li>Incubate at 37°C overnight and count colonies after 18-20 hours of growth</li>
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<li>Count the colonies on each plate with fewer than 300 colonies. Multiple the colony count by the Final Dilution Factor on each plate</li>
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</ul>
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</a>
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<h3 id="results">Results</h3>
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<div class="menu9">
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        <span>OD 600 Reference Point </span>
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        <a href="#"><img src="imagines/OD 600 Reference point .png" width="468" height="200"  alt=""/>
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<p>According to the Reference OD600, We calculate the final result: <br>
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OD600/Abs600=3.818 <br>
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All cell density readings using this instrument with the same settings and volume can be converted to OD600, so that we can use this ratio to convert subsequent experimental data.
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</p>
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      <span>Particle Standard Curve</span>
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      <a href="#"><img src="imagines/Particle standard curve.png" width="1004" height="415"  alt=""/>
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      <p> We prepare a dilution series of monodisperse silica microspheres and measure the Abs 600 in plate reader. The size and optical characteristics of these microspheres are similar to cells, and there is a known amount of particles per volume. This measurement allows us to construct a standard curve of particle concentration which can be used to convert Abs 600 measurements to an estimated number of cells.
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</p>
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      <img src="imagines/Particle Standard Curve1.png" width="690" height="363"  alt=""/>
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      <img src="imagines/Curve_logscale.png" width="683" height="341"  alt=""/>
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<p> The final result:<br>
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  mean of med-high levels=6.24E+08
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</p>
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</a>
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      <span>Fluorescein Standard Curve</span>
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      <a href="#">
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  <p> We prepare a dilution series of fluorescein in four replicates and measure the fluorescence in a 96 well plate in plate reader. By measuring these we generate a standard curve of fluorescence for fluorescein concentration. We will be able to use this to convert our cell based readings to an equivalent fluorescein concentration.
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</p>
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<img src="imagines/Fluorescein standard curve.png"  alt="" width="700" height="411"/>
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<img src="imagines/Fluorescein Curve.png" width="671" height="307"  alt=""/>
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<img src="imagines/Fluorescein Standard Curve (logscale).png" width="672" height="412"  alt=""/> <p> Final results:<br>
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Mean uM fluorescein / a.u.=3.60E-05<br>
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MEFL / a.u.=2.17E+08
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</p>
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</a>
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Revision as of 16:18, 24 July 2018

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Interlab

InterLab

Overview

Poverty in taking reliable and repeatable measurements remains a key obstacle in establishing synthetic biology as an engineering discipline. The Measurement Committee has been studying the measurement procedure for green fluorescent protein (GFP) over the last several years by interlab. The most commonly used markers though GFP is in synthetic biology, labs often resort to making relative comparisons, which makes it difficult for labs to share and data and/or constructs.

The goal of the fifth iGEM InterLab Study is to identify and correct the sources of systematic variability in synthetic biology measurements by answering the question "Can we reduce lab-to-lab variability in fluorescence measurements by normalizing to absolute cell count or colony-forming units (CFUs) instead of OD? "

As we know in the previous study, the fluorescence value measured by a plate reader is an aggregate measurement of an entire population of cells, we need to divide the total fluorescence by the number of cells in order to determine the mean expression level of GFP per cell. Due to the fact that the "optical density (OD)" of the sample is an approximation of the number of cells varying from lab to lab, we decided to use a special silica beads that are roughly the same size and shape as a typical E. coli cell to set up a universal, standard "equivalent concentration of beads" measurement.

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