Difference between revisions of "Part:BBa K343007"

Revision as of 00:26, 27 October 2010

Photosensor generator

Background

This part constitutively expresses the protein from the coding sequence of BBa_K343003, which in turn makes E.Coli phototaxic when exposed to the right conditions. The promoter is inhibited by TetR, which in turn will not be active in the presence of tetracyclin.

Usage and parameters

The part requires retinal to work in E.Coli. This can be achieved through adding retinal to the liquid growth medium and/or the plates. Currently we are doing experiments on wether the part also functions with an internal retinal source, ie retinal synthesis in E. Coli. On top of adding retinal the cells will have to be grown in the dark for at least two hours after the addition of retinal to the growth medium if you want to see an effect. This is so that the photosensor is not exposed to light before the experiments and will result in maximum output if exposed to blue light.

Results

Bacteria containing this part will exhibit a lowered tumbling rate when exposed to blue light (wavelengths around 350nm - 450nm). This was analysed with the help of video microscopy and the open source software [http://db.cse.ohio-state.edu/CellTrack/ "CellTrack"]. The individual cells trajectory was tracked and their speed measured. The tracking results are as follows:

From left to right, trajectory of: E.Coli with photosensor exposed to blue light, E.Coli with photosensor exposed to red light and E.Coli Mg1655 Wildtype exposed to blue light: (Blue dots show the location of the cell in the given frame, so the number of dots equals the number of frames from the sample.)

The phototaxic bacteria move more in a straight line when exposed to bluelight, as can be seen when comparing the trajectories of the thee bacteria given earlier. These were taken from a batch of 10 cells tracked per sample.

Sequence and Features