title: Cosmids: a type of plasmid gene-cloning vector that is packageable in vitro in bacteriophage lambda heads.
abstract: Evidence is presented that ColE1 hybrid plasmids carrying the cohesive-end site (cos) of lambda can be used as gene cloning vectors in conjunction with the lambda in vitro packaging system of Hohn and Murray [(1977) Proc. Natl. Acad. Sci. USA 74, 3259--3263]. Due to the requirement for a large DNA molecule for efficient packaging, there is a direct selection for hybrids carrying large sections of foreign DNA. The small vector plasmids do not contribute a large background in the transduced population, which is therefore markedly enriched for large hybrid plasmids (over 90%). The efficiency of the in vitro packaging system is on the order of 10(5) hybrid clones per microgram of foreign DNA for hybrids in the 20--30 million dalton range.
mesh_terms: D003090:Coliphages / Q000235:genetics; D011088:DNA Ligases / Q000378:metabolism; D004269:DNA, Bacterial / Q000378:metabolism*; D004274:DNA, Recombinant; D004278:DNA, Superhelical / Q000378:metabolism; D004279:DNA, Viral / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism; D005814:Genes, Viral; D008722:Methods; D008970:Molecular Weight; D010957:Plasmids; D011549:Pseudomonas / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D004274:DNA, Recombinant; D004278:DNA, Superhelical; D004279:DNA, Viral; D011088:DNA Ligases