PubMed HealthSearch

PubMed · 8393823

Vectors lambda 200g and lambda 200c: two useful derivatives of lambda 2001.

Abstract

We describe the construction and uses of two new phage lambda replacement vectors. Both are modifications of lambda 2001 which allows selection of cloned inserts by the Spi- phenotype, following the replacement of a gam+ filler fragment. Vector lambda 200g has a second gam gene with an amber mutation in its right arm which enables the selection of clones with inserts in the normal way in Su0 host bacteria and the maintenance of their genetic stability by subsequent growth in Su+ strains. Vector lambda 200c is designed for complementation studies. It contains a cat gene and the attP site of lambda. Recombinants can be inserted into the bacterial chromosome or into an episome with the aid of appropriate helpers.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

C G Koh, L Barnett, S Brenner. 1993-08-16. Vectors lambda 200g and lambda 200c: two useful derivatives of lambda 2001.. https://doi.org/10.1016/0378-1119(93)90353-5

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

Consequences of attachment of Helicobacter pylori to gastric cells.

Helicobacter pylori, a human pathogen and type 1 carcinogen, causes gastritis, gastric ulcers and gastric cancer. In vivo, H pylori colonizes only gastric surface cells from the antral and fundal regions of the stomach, and heterotopic or metaplastic gastric epithelium present within the esophagus and duodenum. This review summarizes what is known about the association and consequences of attachment between H pylori and gastric cells in vitro, and compares this to the findings demonstrated in vivo. It has been shown that attachment of H pylori to gastric cells results in cup and pedestal formation and cytoskeleton rearrangement similar to that described for enteropathogenic Escherichia coli. Attachment of H pylori induces additional cellular changes in the host cell, including cytokine responses and induction of signal transduction pathways.

Attachment Sites, Microbiological

Complete conversion of antibiotic precursor to pristinamycin IIA by overexpression of Streptomyces pristinaespiralis biosynthetic genes.

A Streptomyces pristinaespiralis strain, which produces a streptogramin antibiotic pristinamycin II (PII) as a mixture of two biologically active molecules PIIB and PIIA, was genetically engineered to produce exclusively PIIA. The snaA,B genes, which encode a PIIA synthase that performs oxidation of the precursor (PIIB) to the final product (PIIA), were integrated in the chromosome of S. pristinaespiralis using an integrative derivative of the pSAM2 genetic element from Streptomyces ambofaciens. Integration was due to site-specific recombination at the attB site of S. pristinaespiralis, and no homologous recombination at the snaA,B locus was observed. The attB site of S. pristinaespiralis was sequenced and found to overlap the 3' end of a pro-tRNA gene. The integrants were stable in industrial conditions of pristinamycin production and showed no decrease in PII biosynthesis. Western blot analysis showed a constant production of the PIIA synthase in the overall fermentation process due to expression of the cloned snaA,B genes from the constitutive ermE promoter. This allows the complete conversion of the PIIB form into PIIA.

Attachment Sites, Microbiological