Difference between revisions of "Part:BBa K917002:Experience"
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CIX-SUC plate: 501 small blue colonies, 1 pale red colony | CIX-SUC plate: 501 small blue colonies, 1 pale red colony | ||
| − | This suggests a good degree of counter-selection | + | This suggests a good degree of counter-selection. |
Plates with 10% sucrose (right) or without (left). There are two control lines with lacZ+ (down) and two test lines Plac-RFP-sacB (up) on each plate. One of the test lines has grown much more poorly with sucrose, the other has failed to grow at all. The inconsistent pink colour suggests a high rate of plasmid loss. | Plates with 10% sucrose (right) or without (left). There are two control lines with lacZ+ (down) and two test lines Plac-RFP-sacB (up) on each plate. One of the test lines has grown much more poorly with sucrose, the other has failed to grow at all. The inconsistent pink colour suggests a high rate of plasmid loss. | ||
https://static.igem.org/mediawiki/parts/b/b8/SacB.jpg | https://static.igem.org/mediawiki/parts/b/b8/SacB.jpg | ||
| + | |||
| + | Further experiments are in progress. | ||
===User Reviews=== | ===User Reviews=== | ||
Latest revision as of 21:00, 1 October 2012
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Applications of BBa_K917002
This part is designed for use in counter-selection experiments. Cells are grown in a high-sucrose medium (eg, on L-agar plates with 10% w/v sucrose). Only cells which have lost the cassette should grow. Literature suggests that this counter-selection cassette is prone to failure through loss-of-function mutations in sacB, which may occur at frequencies higher than loss of the cassette. To help distinguish such events, we have added the RFP from BBa-J04450, so that sacB loss of function will still produce red colonies, whereas true loss of the cassette leads to white colonies.
An quick preliminary trial was conducted using the modified version of this cassette, BBa_K917010, with BBa_P1001 kanamycin resistance cassette added. A mixed culture of E. coli JM100/pSBIC3-BBa_K917010 and a control strain expressing lacZ as a marker gene was grown overnight in L-broth. A 1e-6 dilution was prepared and 100 microlitres was plated to L-agar plates with chloramphenicol (40 mg/l), IPTG (90 mg/l) and X-gal (40 mg/l) (CIX plate) and to the same medium with 10% w/v sucrose incorporated (CIX-SUC plate). Colony counts were as follows:
CIX plate: 793 small blue colonies, 115 pale red colonies
CIX-SUC plate: 501 small blue colonies, 1 pale red colony
This suggests a good degree of counter-selection.
Plates with 10% sucrose (right) or without (left). There are two control lines with lacZ+ (down) and two test lines Plac-RFP-sacB (up) on each plate. One of the test lines has grown much more poorly with sucrose, the other has failed to grow at all. The inconsistent pink colour suggests a high rate of plasmid loss.
Further experiments are in progress.
User Reviews
UNIQd2215ac65302143a-partinfo-00000000-QINU UNIQd2215ac65302143a-partinfo-00000001-QINU