IGEM:IMPERIAL/2006/ProjectCalendar/2006-8-21

Monitoring Cell Populations

 * After meeting with Dr. David Leak, the idea of using 3 different antibiotics to monitor cell populations was found promising by the group
 * By adding tetracycline and kanamycin antibiotic resistance genes to the different cell populations respectively, cell populations cal be monitored by taking samples and plating them on the respective antibiotic plate
 * This needs an extra ligation step (3 days) !!
 * Decided to prepare all the plasmids and DNA ready to insert the antibiotic resistance gene if we still have time and need to do it
 * There is an alternative check that we should do regardless beforehand to get some idea of the growth rates of the two populations:
 * Grow up the two cell cultures separately and at different times in the grwoth phase measure the OD
 * If the OD is similar, this will suggest same growth rates and the cell populations will be more probable to stay at a ratio of 1:1
 * If the OD differs very much, we should monitor cell populations throughout using the antibiotic resistances
 * Deepti -Talking to Dr. Jensen this morning, it seems that the 3 antibiotic method is not very accurate an requires extra ligations steps which can be avoided.
 * Waiting for plated samples to grow will require atleast a day before we can assess the differences in population sizes.
 * The number of bacteria in the plated samples does not necessarily accurately reflect the relative proportion in the common broth culture.
 * Even if the plating method were to be an accurate measure of the colony sizes in the broth culture, we could still only record, and not control population sizes
 * According to Dr. Jensen, the best way to do it would be the OD method.
 * By growing up the bacteria separately, we can measure their separate growth rates which, hopefully, should not be too disimilar.
 * When mixing the two cultures, the ODs should be equal, and preferably, between 0.6 and 0.8. -Deepti