Serial Dilutions:

In order to clearly show the growth phenotypes of these mutants on galactose containing media, serial dilutions were carried out. The first round of serial dilutions was not quantitated and the amount of cells in each sample was not consistent. This first round of serial dilutions included all eleven putative mutants. Dilutions of 10-1, 10-2, 10-3, 10-4, and 10-5 were plated onto C-ura, C-ura+2%gal, and C-ura+4%gal and incubated at 30 deg C for 5 days. The expected phenotypes were seen for four of the mutants that did not grow on galactose and the three mutants that grew significantly slower than the control. The other four mutants did not display significant differences in growth when compared to the control. One of the mutants that did not grow on galactose turned out to be contaminated with mold.

The serial dilutions were repeated because I wanted to have the same concentration of cells in each sample and because mold grew on some of the plates. I only studied the seven best mutants. This time, after inoculating one colony of each putative mutant I took the OD610 to determine the concentration of cells and diluted the samples so that the number of cells in each spot would be the same for all the samples. Dilutions of 1, 10-1, 10-2, 10-3, and 10-4 were plated onto C-ura and C-ura+2%gal and incubated at 30 deg C for 5 days. Again the expected phenotypes were seen: four mutants did not grow at all on the galactose media and three grew more slowly than the controls. These serial dilutions on C-ura and C-ura+gal are shown in figure 1.

Figure 1: Serial Dilutions of Putative ytm1 Mutants Showing Lack of Growth or Slow Growth on Galactose Media