Nullomers

Source: Wikipedia, the free encyclopedia.

Nullomers are short sequences of

cross contamination when analyzing crime scene material.[3]

Background

Nullomers are naturally available but potentially unused sequences of

strand breakage.[7] Moreover, it has been shown that statistically significant nullomers (i.e. absent short sequences which are highly expected to exist) in virus genomes are restriction recognition sites indicating that viruses have probably got rid of these motifs to facilitate invasion of bacterial hosts.[8] Nullomers Database
provides a comprehensive collection of minimal absent sequences from hundreds of species and viruses as well as the human and mouse proteomes.

Sequence of Human nullomers of 11bp in length[4]
No occurrence in the Human Genome CGCTCGACGTA, GTCCGAGCGTA, CGACGAACGGT, CCGATACGTCG
One occurrence in the Human Genome TACGCGCGACA, CGCGACGCATA, TCGGTACGCTA, TCGCGACCGTA, CGATCGTGCGA, CGCGTATCGGT
Two occurrences in the Human Genome CGTCGCTCGAA, TCGCGCGAATA, TCGACGCGATA, ATCGTCGACGA, CTACGCGTCGA, CGTATACGCGA, CGATTACGCGA, CGATTCGGCGA, CGACGTACCGT, CGACGAACGAG, CGCGTAATACG, CGCGCTATACG
Three occurrences in the Human Genome CGCGCATAATA, CGACGGCAGTA, CGAATCGCGTA, CGGTCGTACGA, GCGCGTACCGA, CGCGTAATCGA, CGTCGTTCGAC, CCGTCGAACGC, ACGCGCGATAT, CGAACGGTCGT, CGCGTAACGCG, CCGAATACGCG, CATATCGCGCG
Table of the number of nullomers present in different organisms and the nullomer length[4]
Organism 10bp 11bp 12bp 13bp
Arabidopsis 107 23646 1167012 20237388
C Elegans 2 7686 1152038 23339534
Chicken 2 590 131515 4722702
Chimpanzee
 0 136 45938 2426474
Cow
 0 96 45060 2432554
Dog 0 40 25217 1868964
Fruitfly 0 206 221616 12399300
Human 0 80 39852 2232448
Mouse 0 178 54383 2625646
Rat 0 50 30708 1933220
Zebrafish 0 2 15561 2469558

Cancer Treatment

Nullomers have been used as an approach to

mitochondria by increasing ROS production, which reduced ATP production, leading to cell growth inhibition and cell death. Normal cells show a decreased sensitivity to PolyArgNulloPs over time.[2]

Forensics

Accidental transfer of biological material containing DNA can produce misleading results. This is a particularly important consideration in forensic and crime labs, where mistakes can cause an innocent person to be convicted of a crime. There was no way to detect if a reference sample was mislabeled as evidence or if a forensic sample is contaminated, but a nullomer barcode can be added to reference samples to distinguish them from evidence on analysis. Tagging can be carried out during sample collection without affecting genotype or quantification results. Impregnated filter paper with various nullomers can be used to soak up and store DNA samples from a crime scene, making the technology simple and effective.

National Research Council's recommendations on quality control to reduce fraud and mistakes.[3]

References

  1. PMID 17925870. Open access icon
  2. ^
    S2CID 4207067
    .
  3. ^
    PMID 23756524
    .
  4. ^
    PMID 17990505
    .
  5. PMID 15317870
    .
  6. PMID 15448185
    .
  7. doi:10.1021/jp012043n
    .
  8. PMID 33693858
    .
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