Figure 1

Restriction enzyme analysis of canis familiaris and MDCK DNAs. (A) Restriction map of the canis familiaris genomic sequence [GenBank:NW_878945] which encompasses the 18S r RNA gene. The arrow indicates the position of the MDCK 7.1 kb EcoR I fragment which hybridized to the 18S rRNA gene probe. (B) Southern hybridization of MDCK DNA. Left panel: Single restriction enzyme digestions of MDCK DNA were subjected to electrophoresis on a 0.7% agarose gel and detected by ethidium bromide staining. M: 1 kb ladder (Invitrogen); Lanes 1–8: Avr II, BamH I, EcoR I, Hind III, Sac I, Spe I, Sph I, Xba I; C: 18S rRNA gene probe. Right panel: Southern blot of gel in left panel after hybridization to a psoralen-biotin labeled 18S rRNA gene probe (0.5 kb) and detection by chemilumiscense. The 7.1 kb EcoR I fragment (arrow) was cloned and analyzed for RNA pol I promoter activity. (C) Comparison of the size of selected restriction fragments predicted by the canis familiaris genomic sequence to hybridize to the 18S rRNA gene probe and those restriction fragments from MDCK DNA which were observed to hybridize.