Further Molecular Methods
DNA-Arrays DNA-arrays (DNA-chips, microarrays) are tools in medical, pharmaceutical, and biological diagnosis of pathogens (genotyping, pathotyping) (Beier et al. 2002; Wiehlmann et al. 2004). Basis is the increasing availability of sequence information of various viruses and bacteria.
One chip can carry up to 10,000 different DNA probes (e.g., oligonucleotides), which are raster-like bound on its surface. Nucleic acid molecules of the sample hybridize specifically with the corresponding DNA probe, and the hybridized chip areas are detected colori-metrically.
Compared to PCR techniques, the sensitivity of the chip technology is lower than with species-specific PCR, and the chip techniques need experi-enced staff and expensive laboratory equipment. The great miniaturization and automation, however, allow the analyses of a great number of samples in a short time. Specific oligonucleotides to be used for arrays are already commercially available for severalpathogenic bacteria and yeasts. A possible future use for wood fungi using specific oligonucleotides from rDNA sequences (Table 2.8) could be a new technique for fungal diagnosis.