title: Restriction enzyme analysis of plasmids from Haemophilus influenzae.
abstract: Examination of Haemophilus influenzae strains isolated in New Orleans revealed ampicillin-resistant strains with plasmids of size classes not previously detected in North America. The molecular weight of plasmids in five ampicillin-resistant strains ranged from 0.8 x 10(6) daltons (0.8 Mdal) to 36 Mdal. The molecular weights of the plasmids were determined by sucrose gradient centrifugation, electron microscopy, and agarose gel electrophoresis. Plasmids of the previously detected 30-Mdal size class were found in three of the five ampicillin-resistant strains. Restriction enzyme analysis is consistent with a close relationship between these three 30-Mdal plasmids. Of the two remaining ampicillin-resistant strains, one contained a single plasmid of 36 Mdal and the other contained two plasmids of 0.8 and 2.3 Mdal.
mesh_terms: D002499:Centrifugation, Density Gradient; D004262:DNA Restriction Enzymes; D004269:DNA, Bacterial / Q000032:analysis*; D004587:Electrophoresis, Agar Gel; D006193:Haemophilus influenzae / Q000032:analysis / Q000235:genetics*; D008854:Microscopy, Electron; D008970:Molecular Weight; D011815:R Factors
chemical_list: D004269:DNA, Bacterial; D004262:DNA Restriction Enzymes