2. You have chosen Noam's clones
for further characterization. You picked 15 of the clones, replated them
in separate dishes and continued to grow them in the presence of G-418.
When you obtained sufficient amounts of cells from each cell line (and
after freezing samples of each cell line) you started the new analysis.
Cells of each cell line
were transiently transfected with the following plasmid:
Each cell suspension was
devided and plated to 2 different wells (G-418 and hygromycin was added
to the medium). Two days later you added tetracyclin to one well from each
cell line and added only the tet buffer (blank reagents) to the other well
(to compare the GFP expression in induced vs. noninduced systems). After
two more days you examined the cells in a confocal microscope.
Here are the results
obtained from six different clones.
(Click on any clone number
to get more details.)
Which of the following
sentences is correct?
Choose between right and
Examine ALL answers
The tet-induced repression in Noam-1 cells is so tight that even in tet
absence GFP is not expressed.
Noam -6 cells express the tet-element + reporter gene, but the tet control
over the expression is so loose that maximal expression is achieved even
in tet's presence.
Noam-7 cells are leaky. In spite of tet presence there is considerable
expression of GFP, and the signal is only slightly increased in tet absence.
Noam-10 is the ideal cell line: the control over the expression is very
tight, and the levels of induced expression are very high.
Noam-13 cell line is not too leaky, but due to plasmid incorporation in
a non suitable location in the viral genome the induced expression is not
The initial cells of the Lior-15 clone survived due to inefficient exposure
to G-418, but they did not incorporate the plasmid.