Lorist6, a cosmid vector with BamHI, NotI, ScaI and HindIII cloning sites and altered neomycin phosphotransferase gene expression.

Four new features have been included in a phage-lambda-replicon-based cosmid vector, Lorist6. A ScaI restriction site allows insertion of blunt-ended DNA, partially digested with AluI or any other restriction enzyme which creates blunt ends after cleavage. NotI and BamHI sites enable construction of libraries using double digestion with NotI + Sau3AI. The promoter of the neo gene has been substituted by a promoter derived from the tet gene of pBR322, increasing expression of the resistance gene product. A transcriptional terminator has been placed downstream from the neo gene to prevent transcription into insert DNAs.