Cell Language Theory, The: Connecting Mind And Matter

294 The Cell Language Theory: Connecting Mind and Matter

b2861 The Cell Language Theory: Connecting Mind and Matter “6x9”

Figure 7.3 The microarray experiment and typical results. (a) The mRNA isolated from

a biological sample is transformed into complementary DNA (cDNA) using reverse tran-

scriptase and labeled nucleotides which is then hybridized with the probe DNA previously

attached to the microarray surface. Image reproduced from [301, 302]. (b) In two-color or

two-channel microarray experiments, complementary DNA molecules are prepared from

two samples to be compared, e.g., cancer vs. normal cells, with differential labeling. The

fluorescent dyes commonly used for cDNA labeling include Cy3 (cyanine dye 3), which

fluoresces at 570 nm (corresponding to the green color), and Cy5 which fluoresces at

670 nm (corresponding to the red color). The two Cy-labeled cDNA samples are mixed

and hybridized to a single microarray that is then scanned in a microarray scanner to visu-

alize fluorescence of the two fluorophores by exciting with a laser beam or 570 or 670 nm

wavelength. The relative intensities of each fluorophore are analyzed based on a ratio-

based method [303] after proper normalization [304] to identify up-regulated and

(a) (b)

(c)

(d)

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