This assay is used when working with phage vectors carrying the beta-gal gene. If the cloning event disrupts a normally functional copy of the gene in the vector the resulting plaques would appear clear in the assay. If the phages contain a functional beta-gal gene they will form blue rings around their plaques. Any strain which is not an overproducer of beta-gal will work as indicator host bacteria; a single chromosomal copy of the gene is not a problem. - [Read Assay for Phage Containing the Beta-galactosidase Gene]
This assay is used when working with phage vectors carrying the beta-galactosidase gene (often used for immunological screening). If the cloning event disrupts a normally functional copy of the gene in the vector the resulting plaques would appear clear in the assay. If the phages contain a functional beta-galactosidase gene they will form blue rings around their plaques. Any strain which is not an overproducer of beta- galactosidase will work as indicator host bacteria. - [Read Assay for Phage Containing the Beta-galactosidase Gene Protocol]
The procedure is to mutagenize a large population of worms with trimethylpsoralen and UV irradiation, set up 1152 subpopulations, screen DNA made from this library for deletions in specific genes by nested PCR, and then to recover single worms carrying the deletions through a sib-selection process. - [Read C. elegans Gene Knockout Protocol]
Virus-induced gene silencing (VIGS) uses a virus to deliver a sequence from a gene of interest into a host plant. The virus carrying the fragment of the gene of interest must be capable of replication if dsRNA is to be produced. One or two leaves are inoculated with Agrobacterium strains carrying the VIGS vector possessing the gene fragment. The virus then replicates and spreads throughout the plant, mediating silencing. - [Read Delivery of dsRNA into Plants by VIGS Methodology]
Protocol should be viewed as a starting point for systematic optimization of transfection mediated by lipofecting agents. Once a positive signal has been obtained from a transfected plasmid carrying a standard reporter gene, optimal conditions for transfection can be established by systematic variation of parameters such as the initial cell density, the amount and purity of DNA, the media and serum, and the time of exposure of the cells to the cationic-lipid-DNA complex. - [Read DNA Transfection Mediated by Lipofection Protocol]
Protocol for the expression of cloned genes in E. coli using IPTG-inducible promoters. Protocol describes how (1) to clone cloned sequences encoding open reading frames in plasmids carrying IPTG-inducible promoters, (2) to optimize expression of target proteins in transformants carrying these recombinants, and (3) to scale-up production of foreign proteins. - [Read Expression of Cloned Genes in E. coli Using IPTG-inducible Promoters Protocol]
Protocol describes how (1) to clone cloned sequences encoding open reading frames in plasmids carrying bacteriophage {lambda} pL promoters, (2) to optimize expression of target proteins in transformants carrying these recombinants, and (3) to scale-up production of foreign proteins. - [Read Expression of Cloned Genes in E. coli Using the Bacteriophage lambda pL Promoter Protocol]
Protocol for expression of cloned genes in E. coli using the bacteriophage lambda pL promoter. Protocol describes how (1) to clone cloned sequences encoding open reading frames in plasmids carrying bacteriophage lambda pL promoters, (2) to optimize expression of target proteins in transformants carrying these recombinants, and (3) to scale-up production of foreign proteins. - [Read Expression of Cloned Genes in E. coli Using the Bacteriophage lambda pL Promoter Protocol]
Protocol for the expression of cloned genes in E. coli using the bacteriophage T7 promoter. Protocol describes how (1) to clone cloned sequences encoding open reading frames in plasmids carrying bacteriophage T7 promoters, (2) to optimize expression of target proteins in transformants carrying these recombinants, and (3) to scale-up production of foreign proteins. - [Read Expression of Cloned Genes in E. coli Using the Bacteriophage T7 Promoter Protocol]
Protocol describes methods for isolation of DNA from a strain of S. cerevisiae carrying a recombinant YAC. Because the linear YAC DNAs are sensitive to shearing forces, pipettes with wide-bore tips should be used to transfer DNAs. The method is suitable for preparing DNA that will be used for agarose gel electrophoresis, Southern blotting, subcloning, genomic library construction, PCR, or other methods that do not require intact high-molecular-weight DNA. - [Read Growth of S. cerevisiae and Preparation of DNA Protocol]
Protocol describes how to identify cloned cDNAs encoding proteins that bind to specific DNA sequences. The methods used are very similar to those used for immunological screening of expression libraries except that the nitrocellulose filters carrying immobilized proteins are screened with 32P-labeled double-stranded DNA rather than with antibodies. - [Read Identifying DNA-binding Proteins in Bacteriophage ambda Expression Libraries Protocol]
Single-stranded templates of bacteriophage M13 DNA containing 20-30 residues of uracil in place of thymine are generated during growth of the bacteriophage in an F' strain of E. coli carrying mutations in the ung and dut genes. This DNA is used as a template in the Kunkel method of oligonucleotide-directed mutagenesis (Oligonucleotide-directed Mutagenesis of Single-stranded DNA). - [Read Preparation of Uracil-containing Single-stranded Bacteriophage M13 DNA Protocol]
Protocol describes methods to superinfect bacteria carrying a recombinant phagemid with a high-titer stock of an appropriate helper virus and to assay the yield of filamentous virus particles that carry single-stranded copies of the phagemid DNA. The key to success in using phagemids is to prepare a stock of helper virus whose titer is accurately known. - [Read Producing Single-stranded DNA with Phagemid Vectors Protocol]
Recombinant proteins engineered to have a polyhistidine tail at either the carboxyl or amino terminus can easily be purified in one step by affinity chromatography on a resin carrying chelated nickel ions. Chromatography can be carried out in column or batch formats. After unbound proteins are washed away, the target protein is eluted using imidazole, which typically preserves the antigenic and functional features of the protein. - [Read Purification of Histidine-tagged Proteins by Immobilized Ni2+ Absorption Chromatography Protocol]
In the first part of this protocol, the linear range of amplification is determined by carrying out 10 identical PCRs in the presence of [{alpha}-32P]dCTP and stopping one reaction after every two cycles. Amplification products are quantified on a denaturing polyacrylamide gel and the results plotted on a graph (counts per minute vs. cycle number). Total RNA is used as an internal control. - [Read Relative RT-PCR: Determining the Linear Range of Amplification and Optimizing the Primers:Competimer]
Plaques formed by M13 bacteriophages or bacterial colonies transformed by plasmids carrying specific mutations can be detected by hybridization, using a radiolabeled oligonucleotide that forms a perfect duplex with the mutant sequence. Hybridization is carried out under conditions of low stringency that allow the radiolabeled oligonucleotide to anneal to both mutant and wild-type DNAs. - [Read Screening Recombinant Clones for Site-directed Mutagenesis by Hybridization to Radiolabeled Oligos]
Protocol describes how to generate a plasmid construct (pBAIT) that expresses a target protein fused to the bacterial LexA protein. PBAIT is cotransformed into yeast with a lexAop-lacZ reporter plasmid carrying the bacterial lacZ gene under the control of the lexA operator. The recipient yeast strain contains a chromosomally integrated leu2 reporter gene, also under the control of the lexA operator. - [Read Two-hybrid Systems Stage 1: Characterization of a Bait-LexA Fusion Protein Protocol]