CIS - cloning of identical sequences between two complex genomes

Development of the methods permitting cloning of identical sequences betwee n two sources of DNA can be very useful for many purposes, including isolat ion of disease genes. Here we describe a new method called CIS (cloning of identical sequences). A combination of digestion with MvnI, treatment with mung bean nuclease, UDG (uracil-DNA glycosylase) and PCR with 5'-methyl-dCT P and dUTP was used to isolate identical sequences between two micro-cell h ybrid lines (MCH). In a control experiment, mouse MCH903.1 and MCH939.2 con taining human chromosome 3 from different individuals, were compared using the CIS procedure. Only background fluorescence in-situ hybridization (FISH ) was achieved. In another experiment, mouse MCH903.1, containing complete human chromosome 3, and rat MCH429.11, containing a part of human 3q from t he same chromosome were compared. The experiment showed that the original M CH429.11 and the DNA purified using the CIS procedure had identical FISH pa tterns to human metaphase chromosomes, thus demonstrating the efficiency of CIS.