 GSI Lumonics Excitable Dyes
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I purified the DNA, ligated it, and transformed it; the gene has to be here somewhere!" In the days before positive selection vectors, a researcher might have screened thousands of clones by hand with an oligo just to find one elusive insert. Today's DNA array technology reverses that approach. Instead of screening an array of unknowns with a defined probe--a cloned gene, PCR product, or synthetic oligonucleotide--each position or "probe cell" in the array is occupied by a defined DNA fragment, and the array is probed with the unknown sample. The typical array may contain all possible combinations of all possible oligonucleotides (8-mers, for example) that occur as a "window" is tracked along a DNA sequence. It might contain longer oligonucleotides designed from all the open reading frames identified from a complete genome sequence. Or it might contain cDNAs--of ...