[A DNA study of rat liver oligonucleosomes enriched by transcriptionally active genes during induction due to the administration of an amino acid mixture].
A highly active fraction of rat liver oligonucleosome DNA has been isolated and studied by means of thermal denaturation after induction by amino acid mixture or hydrocortisone. A considerable redistribution of DNA content has been shown in sucrose gradient fractions during these forms of induction. The changes are revealed in melting temperature, differential melting profile of DNA, isolated from actively transcribed chromatine fractions. Analysis of melting profiles shows changes of GC content of oligonucleosome DNA, suggesting that there are differences in activation during two studied forms of induction.
We describe a protocol to screen for protein-protein interactions using the Gal-4 based yeast two-hybrid system. In this protocol, we describe serial transformation of bait into an already constructed cDNA library in yeast AH109 cells. We find this method to gives the most number of true interactions. Where a pre-made library in yeast cells is not available, the method outlined can be quickly adapted. AH109 cells can be first transformed with bait containing a vector followed by selection of yeast containing the bait. A second transformation of yeast cells is then accomplished with the cDNA library. The method is quick and can lead to the discovery of significant interactions.