Abstract: Methods of manipulation of nucleic acid, in particular amplification by means of the polymerase chain reaction (PCR), including use of oligonucleotides and combinations and kits comprising such oligonucleotides, also methods comprising use of nested PCR, allowing for improved results in methods wherein large numbers of nucleic acid fragments are manipulated by means of PCR and electrophoresis. Oligonucleotides are provided for use a size standards in electrophoresis, and internal controls allowing for calculation of relative amounts of material present. Improved results can be achieved in methods of profiling mRNA transcribed in a system under investigation.