Pairs of oligonucleotide primers used in PCR are often designed with restriction sites in their 5' regions. In many cases, the sites are different in the two primers. In this case, amplification generates a target fragment whose termini now carry new restriction sites that can be used for directional cloning into plasmid vectors. The purified fragment and the vector are digested with the appropriate restriction enzymes, ligated together, and transformed into E. coli. - [Read Cloning PCR Products by Addition of Restriction Sites to the Termini of Amplified DNA Protocol]
Bouin’s fixative is a particularly good choice for worms because it penetrates dense tissues well and is extremely good for fixing antigens. Like all strong fixatives, however, it is unsuitable for some antibody-antigen pairs. In such cases, the length of time in the Bouin’s fixative can be shortened, or paraformaldehyde fixation can be used instead. - [Read Fixing Caenorhabditis elegans in Bouin’s Fixative Protocol]
There are multiple variations to this protocol, but they find that this one works well in all cases tested. Mirmira Lab. - [Read General EMSA Protocol]
Coimmunoprecipitation is most commonly used to test whether two proteins of interest are associated in vivo, but it can also be used to identify novel interacting partners of a target protein. In both cases, the cells, which may have been labeled with [35S]methionine, are harvested and lysed under conditions that preserve protein-protein interactions. The target protein is specifically immunoprecipitated from the cell extracts, and the immunoprecipitates are fractionated by SDS-PAGE. - [Read Identification of Associated Proteins by Coimmunoprecipitation Protocol]
There are several manual methods that can be used to perform tissue microdissection. Techniques using hand-held tools as well as mechanical micromanipulator-based approaches have been described. However, speed and precision are the most important parameters and any method that achieves these is adequate. Investigators should also expect to invest time initially by practicing on 10 to 20 cases to begin to feel comfortable with the technique. - [Read Manual Microdissection]
Some yeast strains are unstable (e. g., small YAC-bearing strains) and need to be repurified by streaking on an agar plate and then verifying the genetic content of the isolated colony before proceeding. In cases where the strain is unstable, plan to streak the cells onto the selective medium to retain the desired stock, (however, most strains can be streaked onto the complete medium, YPD). - [Read Streaking Yeast Stocks Protocols]
Searches are not constrained for only tryptic peptides, and indexed databases (databases only containing tryptic peptides) are not used. In cases where there are very complex mixtures, such as cell lysates, nonspecific cleavages can occur. Therefore, nontryptic peptides would be missed in the database search. - [Read The Use of Mass Spectrometry in Proteomics: Database Searching]
No cell culture problem is as universal as that of culture loss due to contamination. All cell culture laboratories and cell culture workers have experienced it. Culture contaminants may be biological or chemical, seen or unseen, destructive or seemingly benign, but in all cases they adversely affect
both the use of your cell cultures and the quality of your research. Contamination problems can be divided into three classes: Minor annoyances, Serious problems, Major catastrophes. - [Read Understanding and Managing Cell Culture Contamination Protocol]
Procedure describes how it denatures most of the modification and degradation proteins immediately giving the most accurate read out of the true levels of protein at the time of harvest. However, in cases where detection is a problem, a limited purification (e.g. isolation of nuclear extract for the detection of transcription factors) might be required to allow analysis. - [Read Western Blot Analysis of Endogenous Gene Expression Protocol]
The DNA Ligation protocol described here contains the steps required to join together using ligase enzyme both plasmid DNA and insert DNA fragments in order to create a new plasmid. This new ligated plasmid can be transformed after into competent bacteria to produce DNA for mini, midi or maxi-prep isolation.