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Amplified DNA Product Separation for Forensic Analysts

Slab Gel and Silver Staining

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Slab Gel and Silver Staining
National Institute of Justice (NIJ) (see reuse policy).

D1S80 is a locus on chromosome 1 that consists of a variable number of tandem repeats (VNTR) of a 16 base pair (bp) sequence. Characterization of D1S80 was the first application involving the separation of amplified DNA in forensic science. The process utilized a vertical polyacrylamide slab gel with a discontinuous buffer (TBE, tris-borate-EDTA) system to separate the amplified fragments. The gel was visualized using the simple procedure of silver staining, which allowed for suitable sensitivity and the ability to maintain a permanent record of the gel. Determination of the fragment size was done using the D1S80 allelic ladder which contained multiple alleles of 14 to 41 repeats. Sizing was done by directly comparing the allelic ladder bands in adjacent lanes on the PAG to samples bands.

D1S80 was soon replaced by short tandem repeats (STR) with 4 base pair sequences. These allow for multilocus amplification or multiplexing, real-time fragment detection, automation, and provide much higher discrimination.

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