Automatic DNA synthesizer

Oligonucleotide modified with thiol (-SH) group is synthesized in our laboratory on an automatic Applied Biosystems DNA synthesizer, model 392, and according described procedure (35). 

An automatic sequencing instrument has been developed that uses the chain-terminator method. To avoid the use of radioactive labels, a different color fluorescent dye is attached to the primer in each of the four reactions used to synthesize the DNA fragments. The mixture of fragments from all four reactions is then analyzed using electrophoresis in a single lane. A fluorescent spot appears for each polynucleotide of increasing size. The 3 -terminal base for each spot can be determined by the color of the fluorescence. The detection system is computer controlled, and the acquisition of data is automated. A schematic representation... 

A T or A U and G C pairs, make it possible to build regular double-stranded structures of arbitrary base sequence and to provide a mechanism to copy the genetic code. That is, if the sequence of one strand of DNA is known, the sequence of the other strand is determined automatically. Therefore, if the strands are separated and new DNA is synthesized, two double-stranded DNA molecules are obtained, each an exact copy of the original. 

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