Oc90^df1H5R

An HSV-tk/beta-actin-neo cassette was inserted into intron 2 using a gene targeting strategy. ES cells expressing both markers were selected. After X-irradiation of properly targeted ES cell lines with 400 rad, loss of tk expression was determined using FIAV. Cells no longer expressing tk were further tested for loss of neomycin expression. SSLP typing of polymorphic microsatellite markers determined that this allele contains a deletion of greater than 148 kb and may be a skipping deletion. FISH confirmed deletion of genomic sequence. (J:102039)