Team:PKU Beijing/Notebook/AND Gate 1/Input/LacI TetR 6

Some interesting result from pLac-RFP

Motivation:
we want the low copy plasmid backbone pSB4A5, and we know that the strain JM 109 has lacQ on its F plasmid. We wonder if the lacI expressed from F plasmid can repress the pLac on the pSB4A5.

Parts:
J04450 (backbone is pSB4A5)

Resource:
J04450: from Lin Min, Plasmid

2009.8.13

Transformation:
Plasmid J04450, competent cells JM109 100uL,
Smear to LB plate with Amp

2009.8.14

The colonies on the plate became a little red, after 24 hours.
But compare to no RFP colonies, they are just a little brighter.
The second picture is for comparison with no GFP colonies.

2009.8.16

Inducing:
Transfer one colony into 5mL LB, when it grows to OD 0.4~0.6. Add some IPTG (1mM) to induce, and half without any IPTG, as a control.
After 4 hours, the difference is obvious:

The left one is control, the right one is induced.

Result & discussion

The result suggests that we can make use of the lacIQ on the F plasmid of JM 109, if the pLac is on a low copy plasmid (such as pSB4A5, copy number=5). The amount of lacI can largely repress the expression of pLac. So, maybe we can construct the AND gate only use pLac, without any other lacI on that plasmid.

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