Specific hybridization in the presence of biotin-labeled wild-typeArabidopsis cRNA. The M13 capture probe was coupled to microspheres and the complementary sequence tagged with biotin was used as a target in this experiment. The M13 target oligonucleotide was added as 0.1, 1.0, 10.0, and 100.0 fmoles to the assay in the absence or presence of the indicated amount of biotin-labeled cRNA prepared from wild-type Arabidopsis leaves. In the presence of 10 μg of cRNA, the addition of 0.1, 1.0, 10.0, and 100.0 fmoles of target was approximately equal to a spiking ratio of 1:300,000, 1:30,000, 1:3,000, and 1:300, respectively.