Team:ETH Zurich/project/overview/implementationsimple

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Revision as of 15:37, 10 October 2014

E Coli bacteria are able to communicate together by producing molecules that are able to go through their cell membrane. These molecules are called quorum sensing molecules. In our project Mosaicoli, every cell colony on the grid is able to sense quorum sensing molecules coming from the two colonies above it, and to produce a quorum sensing molecule for the next colonies below it.

In order to make a pattern appear on our grid, we need to tell every cell on this grid :

to sense the signals coming from the 2 cells above. It can be one red signal, one blue signal, both signals, or no signal at all.
to produce a fluorescent protein and a signal towards the cells below, if it sensed only a blue signal, or if it sensed only a red signal.
to produce nothing if it sensed both signals, or if it didn't sense any signal.

For the first point (sensing the signals coming from above), we added in every cell some genes (luxR and lasR) that produce some proteins (LuxR and LasR) that will bind respectively the blue and the red quorum sensing molecules. The blue and red complexes created this way trigger the production of other proteins called integrases (Bxb1 and ΦC31).
For the second point you can see on the picture above that the gene coding for the green fluorescent protein sfgfp can't be expressed if a terminator T is present upstream in the sequence. You can notice also that if one of the 2 integrases Bxb1 or ΦC31 is present, it can bind to two sites around the terminator, cut the sequence and flip this terminator, and thus sfgfp can be expressed again. When sfgfp is expressed, an enzyme called LuxI or LasI is also produced which triggers the production of a quorum sensing molecule. So thanks to these sites which can be recognized by integrases, our cell is able to satisfy the second point.
It is easy to understand that if no signal is coming at all from above, the cell doesn't produce anything. If both signals are coming from above, both integrases will be produced, and the terminator will be flipped twice, so it comes back to its initial state and nothing is produced. So the third point is satisfied.

If you want to know more about quorum sensing and integrases, you can read the article Biological tools in our Background page.

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-On our chip, bacterial colonies of the species <em>Escherichia Coli</em> producing two different types of signals are arranged in an alternate way.
-<br/>
+E Coli bacteria are able to communicate together by producing molecules that are able to go through their cell membrane. These molecules are called quorum sensing molecules. In our project Mosai''coli'', every cell colony on the grid is able to sense quorum sensing molecules coming from the two colonies above it, and to produce a quorum sensing molecule for the next colonies below it.
-<br/>
-[[File:ETH_Zurich_3Dprint_agar_plate.png|center|600px]]
-<br/>
+In order to make a pattern appear on our grid, we need to tell every cell on this grid :
-<br/>
+# to sense the signals coming from the 2 cells above. It can be one red signal, one blue signal, both signals, or no signal at all.
+# to produce a fluorescent protein and a signal towards the cells below, if it sensed only a blue signal, or if it sensed only a red signal.
+# to produce nothing if it sensed both signals, or if it didn't sense any signal.
-In order to implement rule 6 in our cells, we insert genes in their DNA that tell them to produce a molecule QSp or QSq depending on the signals QSp and QSq they receive from above. These signals are called quorum sensing molecules. Cells need to integrate signals they receive in order to know when they should produce a signal. This integration is made possible in the cells by molecules called integrases. To know more about these biological tools, you can read the article [[Team:ETH_Zurich/project/tools|Biological tools]].
+#For the first point (sensing the signals coming from above), we added in every cell some genes (''luxR'' and ''lasR'') that produce some proteins (LuxR and LasR) that will bind respectively the blue and the red quorum sensing molecules. The blue and red complexes created this way trigger the production of other proteins called integrases (Bxb1 and ΦC31).
+#For the second point you can see on the picture above that the gene coding for the green fluorescent protein ''sfgfp'' can't be expressed if a terminator T is present upstream in the sequence. You can notice also that if one of the 2 integrases Bxb1 or ΦC31 is present, it can bind to two sites around the terminator, cut the sequence and flip this terminator, and thus ''sfgfp'' can be expressed again. When ''sfgfp'' is expressed, an enzyme called LuxI or LasI is also produced which triggers the production of a quorum sensing molecule. So thanks to these sites which can be recognized by integrases, our cell is able to satisfy the second point.
+#It is easy to understand that if no signal is coming at all from above, the cell doesn't produce anything. If both signals are coming from above, both integrases will be produced, and the terminator will be flipped twice, so it comes back to its initial state and nothing is produced. So the third point is satisfied.
+If you want to know more about quorum sensing and integrases, you can read the article [[Team:ETH_Zurich/project/tools|Biological tools]] in our Background page.