Genetic Markers for the Selection and Screening of Lambda Vectors, Blue Colonies, White Colonies, Foreign DNA

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Cloning and Expression Vectors Cloning and Expression Vectors Introduction Cloning Vectors for Recombinant DNA Plasmids as Vectors Three Phases of the Development of Plasmid Cloning Vectors Alpha-Complementation for Screening Using "blue-white"Clonies Nonsense Suppressors to Complement Termination Codons in Vectors E.Coli Plasmid Vectors pBR322 and pBr327 Vectors pUC Vectors pSP64-pSP65 pGEM-3, pGEM-4, pGEM-3Z, pGEM-4Z ΠAN13 from ΠAN7 Yeast Plasmid Vectors Retriever Vectors Agrobacterium Plasmid Vectors Lambda Phage (λ)Vectors Lambda Phage (Lysis and Lysogeny) Genetic Markers for the Selection and Screening of λ Vectors Development of Lambda (λ)Phage Vectors Insertion λ Vectors Replacement λ Vectors M13 Phage as a Vector for DNA Sequencing M13-vectors-of-mp-Series Hosts for M13 Vectors Cosmids as Vectors Phagemids as Vectors Phagemids pUC118 and pUC119 Phagemid pBluesript IIKS

Home >> Biotechnology and Genomics >> Cloning and Expression Vectors >> Genetic Markers for the Selection and Screening of Lambda Vectors

Your Ad Here	Genetic markers for the selection and screening of λ vectors. (a) β-galactosidase. Some of the vectors contain a segment of E. coli lacZ gene coding for α peptide, that is capable of complementing the defective lacZ gene (deletion in the region of α peptide) in the host giving blue colonies. These vectors give white colonies, due to lack of ex complementation, whenever there is an insertion of foreign DNA.
(b) Lysogeny. Some of the vectors contain a cI gene with an EcoRI site, so that the vector is Cr⁺ and forms lysogens in hosts carrying a mutation hfl (high frequency lysogenization). Lytic growth is greatly reduced, when wild type vector with intact cI infects, but cI gene is disrupted, when foreign DNA is inserted, leading to lytic growth and phaque formation.
(c) Sensitivity to P2 interference (Spi⁺/Spi^-). In some of the replacement vectors, genes red and gam (genes involved in recombination) are present in the stuffer region, rendering them Spi⁺ (sensitive to P2 prophage interference, i.e. restricted growth on the host, which are lysogens and carry P2). When stuffer region is removed, red and gam are lost rendering the recombinant vector red^- gam^- and consequently Spi^- (growing well in P2 lysogens as long as they carry chi site and rec⁺). The vectors carrying red and gam in the stuffer region include 2001, DASH and EMBL series.	Your Ad Here
(d) Chi site. Wild type lambda contains no chi site (a suppressor of small plaque phenotype in red^- gam^-) and therefore when they are red^- gam^- genotype, in the presence of chi site, it does not form small plaques, but instead forms normal plaques as in case of red⁺ gam⁺ genotype. It is for this reason that in the replacement vectors like those of EMBL series, red and gam genes, are present in the stuffer region and chi site is present elsewhere, so that when red and gam are lost with the stuffer, the vector, despite being red gam forms large colonies (due to chi site).

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BACs and PACs as Vectors for Cloning large DNA Segments (100-300 kb) Bacterial Artificial Chromosomes (BACs) P1-derived Artificial Chromosomes (PACs) Plant and Animal viruses as Vectors Plant Viruses (Cauliflower Mosaic virus or CaMV and Geminiviruses) Animal Viruses Transposons as Vectors Transposons of Higher Plants (Ac/Dc or Mul of Maize) Transposons of drosophila (P elements) YAC and MAC Vectors for Cloning very large DNA Segments (1000 kb) Yeast Artificial Chromosomes (YACs) Mammalian Artificial chromosomes (MACs) Expression Vectors Promoters Nopaline Synthase (nos) Promoter from T-DNA Dual Promoter of Mannopine Synthase (mas) genes 1 and 2 35S Promoter of CaMV Polyhedrin Promoter from Baculovirus Expression Cassettes Baculovirus and Expression Vector System for Insect Cells Virus Expression Vectors for Mammalian Cells Binary and Shuttle Vectors

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