Friday, June 26, 2009

Edge Detector Paper

The genetic edge detector paper just came out in Cell! Congratulations to Jeff and everyone else who worked on this paper. This is a project that we hatched about 3 or 4 years ago and it is finally out after a lot of hard work by everyone involved except me :-).

The project engineered bacteria to act as a communal signal processor implementing an "edge detector". You can think of the engineered bacteria as being like very simple computers, each running the following program: "Am I in the light? If so, shout to my neighbors. Otherwise, if I'm in the dark and I hear my neighbors shouting then raise my hand." Those that are in the dark and hear a neighbor must be near an edge. The "shout" is implemented by having the cells produce a small molecule which diffuses to their neighbors to be "heard" (actually, "smelled" is a better description). The "raise my hand" is implemented by having the cells produce a dark sugar which is visible to the naked eye when you look at the plate.

Interestingly, natural cells implement this edge-detection algorithm: the retina -- the first stages of image processing in the eye is to extract edges by a similar algorithm. The Nobel prize was awarded in 1967 to Hartline for this discovery in the retinas of the horseshoe crab.


Anonymous said...

cells produce a dark sugar which is visible to the named eye
i assume it's the naked eye that sees the dark sugar.

Zack Booth Simpson said...

Fixed "named" to "naked". Thanks Anonymous!

Etha said...

hehe, I like your comparison of "engineered bacteria" to "natural cells" like that in the retina. This would be, for edge detection, our big friends the horizontal cells?
I wonder if this research could shed some light (pun intended) on the things that happen when people loose their contrast vision due to the use of traditional antidepressants (like fluoxetine/prozac etc).....