From 2010.igem.org

Revision as of 23:52, 22 October 2010

Why E.lemming?

The Norwegian Lemming (Lemmus lemmus)

Lemmings are nice rodents, leading a happy and fulfilling life in the cold Arctic regions [1]. Living is very good and easy, so the lemmings reproduce and their population keeps increasing, until it becomes unfeasibly large. This increase in population is followed by a sudden dramatic decrease, for which no biological explanation has so far been provided [2]. However, the mythical explanation exists and it says that, from times to times, the lemmings suffer a panic attack, pushing them to what is legendary known as 'the mass suicide' of the lemmings [3]. According to the legend, during these crazy periods, lemmings can be seen chaotically swimming in the turbulent, cold and dangerous Norwegian rivers and, most of the times, they won't make it to the other shore.
If driven by an interior mysterious urge or by a complete loss of rationality, we don't know. What we do know is a way to design our own synthetic E. colis, which we'll call E. lemmings.

Screenshot from the Lemmings game

Our idea is based on one of the most popular computer games of all times: 'Lemmings' [4], in which the player has to guide the virtual lemmings through challenging routes and avoid difficult obstacles. The goal of the game is to save as many lemmings as possible and prevent them from committing mass suicide.

Our E.lemming is even more clever than the virtual Lemmings you were used to. Not only it is alive, but it can also be created in any biology lab working with E.coli. All you need to do is set the direction with the joystick and E.lemming will mindlessly travel towards the destination. This will turn you into the tiny E. lemming's personal savior, by keeping it as far as possible from the turbulent Norwegian rivers.

Project Idea

Screenshot from the E. lemming game

We control the movement of a single E. coli cell by light. In wild type E. coli flagella movement is controlled by proteins of the chemotaxis pathway, so called Che proteins. In our engineered cells one of these Che proteins is fused to a synthetic light-sensitive localization system. Two external inputs - red light and far red light - induce the relocation of the fused proteins, thus reversibly changing flagella movement direction. Cells, imaged by bright field microscopy, are automatically detected and tracked while a closed loop controller guides the cell into a user defined direction by autonomously sending light inputs. This makes our engineered cell the smallest remote controllable living robot on earth.

References

[1] [http://onlinelibrary.wiley.com/doi/10.1111/j.1439-0310.1995.tb00900.x/abstract Stenseth, N.C. & Ims, R.A. (eds.). 1993. The biology of lemmings. Academic Press, London]

[2] [http://findarticles.com/p/articles/mi_m2120/is_n5_v79/ai_20998373/ Boonstra, R., Krebs, C.J. & Stenseth, N.C. 1998. Population cycles in small mammals: the problem of explaining the low phase. Ecology 79, 1479-1488]

[3] [http://www.wildlifenews.alaska.gov/index.cfm?adfg=wildlife_news.view_article&issue_id=6&articles_id=56 Lemming Suicide Myth]

[4] [http://www.javalemmings.com/DMA/Lem_1.htm Lemmings Video Game ]