Team:TU-Eindhoven

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• Project
  • Project description
  • Lab approach
  • Device information
  • Initial model
  • Yeast model
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• Considerations
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• Notebook
  • Before week 1
  • Week 1
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  • Week 5
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  • Week 7
  • Week 8
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  • Week 11
  • Week 12
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The aim of this project of the iGEM team of Eindhoven University of Technology in 2012 is to design and produce a new multi-color display in which genetically engineered cells function as pixels, analogous to how a flat panel display works. The challenges are in reaching a high refresh rate of the screen, but also in creating a multi-color prototype. There are three components to the display: Genetically engineered cells that emit light in response to an electrical stimulus (the `pixels'), a device to provide stimuli to each pixel (the `control grid'), and a computational model that predicts how cells will react to stimuli from the device. The basic biological parts used in this project are yeast cells, fluorescent calcium sensors and calcium channels. The laboratory work will focus on integrating these parts and establishing the desired reactions to electrical stimuli in order to create the `pixels' of the display. Computational modeling will provide insight into the electrophysiology of yeast cells, the role of calcium channels and the most sensitive parameters in calcium homeostasis in order to optimize the biological system. Engineers will build an electronic device that is compatiable with biological material to provide control over the pixels. The custom build hardware of the device is complemented with software written in LabView to generate images on the screen.

Wetwork

In the lab we will make living cells that emit light in response to an electric stimulus. This can be achieved by genetic modification of yeast cells, through the introduction of fluorescent calcium sensors and calcium channels. The plasma membrane of the brewer's yeast \emph{Saccharomyces cerevisiae} contains the Cch1-Mid1 channel that is homologous to mammalian Voltage Gated Calcium Channels (VGCCs). It is hypothesized that upon depolarization of the plasma membrane calcium ions selectively enter the cytoplasm through Cch1-Mid1. Light will be emitted through the fluorescence of the GECO protein, a calcium sensor that is expressed from a genetically engineered plasmid. When the calcium concentration is high the GECO protein is fluorescent, when the calcium concentration is low the GECO protein is not fluorescent. So upon electrical stimulation cells will let calcium into the cytoplasm and GECO proteins will start to fluoresce. After a while the calcium concentration will drop to homeostatic levels through active transport of calcium ions to the yeast's vacuole and fluorescence will cease. The time required to switch the light on and off should be as short as possible. Therefore, we will try to increase the number of calcium channels through over expression of the channel proteins so that calcium can enter the cell faster upon electrical stimulation. All this calcium that enters the cell has to be pumped out eventually to maintain a healthy cell. It seems that calcium is stored in the cell's vacuole before being excreted. The capacity for storage of calcium ions in the vacule is unknown, as is the rate a which cells can excrete calcium. There may be unexpected side-effects that have to be investigated.

Modeling

To model the calcium homeostasis of yeast cells, a basic calcium model based on sympathetic ganglion `B' cells of a bullfrog is used. This is a type of nerve cells which exists in nerve junctions of the orthosympathetic nervous system. In the model, the main contributions of calcium transport are defined, namely ionic current flows of calcium, diffusion, buffering and pumping. This model will need to be adapted to a calcium model for yeast cells. Some information will be difficult to find in literature, especially when the yeast cells obtain fluorescent properties based on calcium, which is why yeast cell and enzyme specific information is also needed from experiments in the laboratory. This requires a strong collaboration between the team in the laboratory and the team responsible for modeling.

Device for membrane depolarization

The device will be at the heart of the screen, creating a voltage over certain yeast cells that will emit fluorescent light as a result. This is controlled by a computer with the aid of LabView. The materials used in the device are biologically inert, i.e. not toxic or damaging to living cells. The device will not only contain an electrode matrix, but also a backlight as a source to invoke fluorescence. Filters will be used to ensure only fluorescent light originating from the yeast cells will actually produce light on the screen.

Achievements in iGEM competition

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Please see iGEM official results page to see how all the teams did.

In the news

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