Team:SBS NY/Demonstrate
Project Demo
Project Overview
Through a cross-examination between how different regulatory genes react to different metals under various concentrations, a measurement indicated by the intensity of flourescence under the flourescence detector, we are able to establish a model that approxiamates the concentration in the sample. We envision that more repetition of our measurement in the future will provide us with sufficient data to build an arithmetic, which will be installed on our device to precisely calculate the metal composition in a given soil sample, benefiting farmers, environmentalists, and the general public.
MerR-like Heavy metal inducible repressor based Biosensors
In the absence of heavy metal ions, MerR-like regulators will form homodimers that will bind to pMerT promotor region, preventing RNAP from binding to the promoter region and can thus prevent transcription of the gene from taking place.
Once heavy metal ions are present, they will bind to the pMerT promoter region and replace the homodimers. Therefore, as homodimers detach from the promoter region, the initiation of gene transcription -- in our case, the transcription of the MerR-GFP genes, which will glow once expressed -- is enabled.
Based on the mechanism in which MerR-like regulator works, we added a GFP gene after the inducible promoter to visualize the gene expression.
Experiment Result
We were able to insert the merR-like regulator’s genes into the pSB1C3-GFP plasmids and then transform the plasmid into DH5a strain E.coli. After we grow bacteria with each merR-like regulator gene, we were able to get the fluorescent reading of the expression of each gene under different concentrations of heavy metal, and found a correlation between heavy metal concentration and the level of expression: the higher the concentration, the higher the expression level. Some of the curves are shown below:
The raw data and procedures can be accessed by:
Lab_notebook Lab Procedures Fluorescent Reading Raw DataModeling Our Project
Because it is not possible to experiment how the four regulatory genes react to all possible combination of four metals under different concentrations, we have to establish a model that could help us predict, based on how each regulatory gene react to the liqui from soil sample, how much of each metal is in the sample. Therefore, we have tested how each regulatory gene reacts to one metal and multiple two metal combinations, expecting that our mathematical algorithms(the specifics of which you could find in MODELING part of our wiki) could extend the relationship from one or two dimensions into four dimensions(when the sample has four metals in it).
Although the experiment data, for especially the intensity of fluoresence proteins, have roughly reflected the ion concentration, the high accurate result is also meaningful. Also, our detectors as biological elements are much more complex than physic instruments due to nonlinear property. Therefore, model helps us understand and interpret data properly.
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Our Hardware
Our team built a smart device for fast and accurate measurement of multiple heavy metal cations with an innovated all-solid-state green fluorescent protein (GFP) sensor, which is composed of a blue Light Emitting Diodes, an excitation filter, a sample slot, an emission filter and light to voltage converter. Building on existent device, we added on our unique software, which was made up by our model. We employed our formula in our model, and then used the model as a base to develop our software. With its built-in microcomputer and the assistance of our team’s mathematical models and software, it can monitor the heavy metal in the soil efficiently and accurately. The advantages of our invention not only give an accurate result but also is very practical and user-friendly. The whole set of the equipment is very cheap, and itself contains a fully functional microcomputer, which can let the data to be read and process remotely, making it easier yo use in mobile lab van. In contrast with the old equipment such as ICP-MS and ICP-AES, Our design takes the speed of measurement during an emergency of heavy metal leaking to the next level. It is now much more flexible, allowing researchers to bring less tools, and also able to transport data in a faster speed, doing it in a remote way.