Comparison of two molecular weight markers used in DNA-profiling.
DNA-profiling was performed on DNA from human blood samples. Restriction was performed with HinfI and the fragments were analysed with the single locus probes MS1, MS31, MS43a, and YNH24. Calculations of the sizes of DNA-fragments in the range from 1.4 to 22 kilobase pairs (kb) were performed with two different size markers: the Amersham marker SJ5000 and the Gibco BRL marker 4401SA. The standard deviation of the difference between duplicate determinations was significantly lower with the Gibco BRL marker than with the Amersham marker. Calculation of the fragment lengths with the two markers differed significantly, especially in the high molecular weight region (> 8 kb). Fragment lengths were 3-8% (kb) higher with the Amersham marker than with the Gibco BRL marker which corresponds to a difference of 1.0-1.8 mm in migration distance. The difference was enhanced in the presence of ethidium bromide. The consequences of the replacement of the Amersham marker by the Gibco BRL marker in practical casework is discussed.
Institute of Forensic Genetics, University of Copenhagen, Denmark.
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Eriksen
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Svensmark
D016172:DNA Fingerprinting / Q000379:methods* / Q000592:standards; D015342:DNA Probes / Q000737:chemistry*; D004996:Ethidium / Q000494:pharmacology; D005069:Evaluation Studies as Topic; D005554:Forensic Medicine; D006801:Humans; D008970:Molecular Weight; D012150:Polymorphism, Restriction Fragment Length
D015342:DNA Probes; D004996:Ethidium