Difference between revisions of "Team:Ruia-Mumbai/InterLab"

Revision as of 12:43, 13 October 2018

1. OBJECTIVE Reliable and repeatable measurement is a key component to all engineering disciplines. The same holds true for synthetic biology, which has also been called engineering biology. However, the ability to repeat measurements in different labs has been difficult. The goal of the fifth International InterLab Measurement Study is to identify and correct the sources of systematic variability in synthetic biology measurements, so that eventually, measurements that are taken in different labs will be no more variable than measurements taken within the same lab.The previous Interlab studies showed that by measuring GFP expression in absolute fluorescence units calibrated against a known concentration of fluorescent molecule ,can greatly reduce the variability in measurements between labs. However, when taken bulk measurements of a population of cells (such as with a plate reader), there is still a large source of variability in these measurements: the number of cells in the sample. This is because 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. Usually it is done by measuring the absorbance of light at 600nm, from which we compute the “optical density (OD)” of the sample as an approximation of the number of cells. OD measurements are subject to high variability between labs, however, and it is unclear how good of an approximation an OD measurement actually is. Hence this year’s Interlab study mainly focused on standardizing GFP expression for each cell. The absorbance and fluorescence of the cell populations were used to calculate cell concentration by Calibration Curve method. Moreover, absolute cell number of the samples was obtained by performing Standard plate count. {{}}

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+Reliable and repeatable measurement is a key component to all engineering disciplines. The same holds true for synthetic biology, which has also been called engineering biology.  However, the ability to repeat measurements in different labs has been difficult.
+The goal of the fifth International InterLab Measurement Study is to identify and correct the sources of systematic variability in synthetic biology measurements, so that eventually, measurements that are taken in different labs will be no more variable than measurements taken within the same lab.The previous Interlab studies showed that by measuring GFP expression in absolute fluorescence units calibrated against a known concentration of fluorescent molecule ,can greatly reduce the variability in measurements between labs. However, when taken bulk measurements of a population of cells (such as with a plate reader), there is still a large source of variability in these measurements: the number of cells in the sample.
+ This is because 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. Usually it is done by measuring the absorbance of light at 600nm, from which we compute the “optical density (OD)” of the sample as an approximation of the number of cells. OD measurements are subject to high variability between labs, however, and it is unclear how good of an approximation an OD measurement actually is. Hence this year’s Interlab study mainly focused on standardizing GFP expression for each cell. The absorbance and fluorescence of the cell populations were used to calculate cell concentration by Calibration Curve method. Moreover, absolute cell number of the samples was obtained by performing Standard plate count.