ChemoMetec YC-100 User Manual

Page 36

5 Operation of the NucleoCounter

Setup? haploid

1:Up

2:Down

↵

store

Figure 18 Zero Count Check, step 1

To select the appropriate settings use the keys "1" and "2" to scroll in the list of options.
The options are: Haploid, Diploid and Small. The labels refer to "typical" settings for the
measurement of

Saccharomyces cervesae

. The label of the settings are only to be

considered as guidelines since other factors might influence the intensity of the
observed signals.

The appropriate settings for any type and conditions of yeast cells are best found using
the NucleoView software. The software illustrates Object Intensity Histogram for the
measured sample. In order to determine the settings prepare a sample containing
approximately 1,000 lysed cells per µl (1x10

cells/ml) and measure it on the

NucleoCounter instrument using different sensitivity settings.

Figure 19 Object Intensity Histogram using different sensitivity settings.

The figure above illustrate firstly (on top) a sample measured with too low sensitivity,
seen by the relatively high number of cells found below the sensitivity discriminator at
50. The Object Intensity Histogram at the bottom illustrates the same sample measured
with higher sensitivity, where the main intensity population is observed above the
sensitivity discriminator.

The effect of inappropriate sensitivity setting is an over or underestimation of the cell
concentration. It is difficult to give accurate estimates of the magnitude of the error, but
it can be on the order of between 5 and 30%, so due attention should be given to
choosing the appropriate sensitivity setting.

5.6

Zero Count Check (F50)

The instrument can perform a so called

Zero Count Check (only firmware v 3.04 or

higher). This check is carried out without

without

without cassette in the insertion slit of the instrument

and with the lid closed. The check determines the number of CCD-pixels that show