CHECKERBOARD DNA-DNA HYBRIDIZATION

A method is introduced for hybridizing large numbers of DNA samples ag ainst large numbers of DNA probes on a single support membrane. Denatu red DNA from up to 43 samples was fixed in separate lanes on a single membrane mounted in a Miniblotter(R) 45. The membrane was then rotated 90 degrees in the same device, which enabled simultaneous hybridizati on with 43 different DNA probes. Hybridizations were also performed on lysates of bacterial cells blotted to membranes. A miniSlot(TM) devic e allowed lysates loaded in parallel channels to be aspirated through the membrane, depositing horizontal lanes on the membrane surface. Hyb ridizations were performed in vertical lanes with either digoxigenin-l abeled whole genomic probes or 16S rRNA-based oligonucleotide probes d irectly conjugated to alkaline phosphatase. The method permits the sim ultaneous determination of the presence of multiple bacterial species in single or multiple dental plaque samples, thus suggesting its usefu lness for a range of clinical or environmental samples.