Abstract: The invention relates to a method of preparing a reaction mixture for Polymerase Chain Reaction (PCR) assay and a solution set for PCR. The method comprises providing a sample solution comprising a biological sample to be amplified in said PCR assay and first colorant providing the solution a first color, providing a reagent solution comprising at least one other substance required for performing said assay and second colorant providing the solution a second color different from the first color, and mixing the sample solution and the first reagent solution for providing a mixed solution to be subjected to the PCR process, the mixed solution having, due to said first and second colorants, a third color different from the first and second colors. The invention significantly aids in pipetting PCR assays.

Abstract: The present invention provides a process for the production of nucleic acid encoding a target protein, which comprises: (a) providing an array of RNA or DNA molecules including one or more encoding the target protein; (b) generating a target protein from the array to form RNA-protein or DNA-protein complexes in which the RNA or DNA molecule is non-covalently or covalently bound to the complex; (c) separating the complexes into compartments wherein most or all of the compartments contain no more than one complex; (d) subjecting the complexes to reaction conditions which allow target protein activity; and (e) selecting nucleic acid encoding the target protein on the basis of the activity associated therewith, wherein when the complex is a DNA-protein complex in which the DNA is non-covalently bound, step b) is performed in the absence of separate compartments for each complex.