In situ labeling of DNA reveals interindividual variation in nuclear DNA breakdown in hair and may be useful to predict success of forensic genotyping of hair.
Summary of "In situ labeling of DNA reveals interindividual variation in nuclear DNA breakdown in hair and may be useful to predict success of forensic genotyping of hair."
Hair fibers are formed by keratinocytes of the hair follicle in a process that involves the breakdown of the nucleus including DNA. Accordingly, DNA can be isolated with high yield from the hair bulb which contains living keratinocytes, whereas it is difficult to prepare from the distal portions of hair fibers and from shed hair. Nevertheless, forensic investigations are successful in a fraction of shed hair samples found at crime scenes. Here, we report that interindividual differences in the completeness of DNA removal from hair corneocytes are major determinants of DNA content and success rates of forensic investigations of hair. Distal hair samples were permeabilized with ammonia and incubated with the DNA-specific dye Hoechst 33258 to label DNA in situ. Residual nuclear DNA was visualized under the fluorescence microscope. Hair from some donors did not contain any stainable nuclei, whereas hair of other donors contained a variable number of DNA-positive nuclear remnants. The number of DNA-containing nuclear remnants per millimeter of hair correlated with the amount of DNA that could be extracted and amplified by quantitative PCR. When individual hairs were investigated, only hairs in which DNA could be labeled in situ gave positive results in short tandem repeat typing. This study reveals that the completeness of DNA degradation during cornification of the hair is a polymorphic trait. Furthermore, our results suggest that in situ labeling of DNA in hair may be useful for predicting the probability of success of forensic analysis of nuclear DNA in shed hair.
Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna, Lazarettgasse 14, 1090, Vienna, Austria.
This article was published in the following journal.
Name: International journal of legal medicine
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/21475959
- DOI: http://dx.doi.org/10.1007/s00414-011-0566-5
Medical and Biotech [MESH] Definitions
Primed In Situ Labeling
A technique that labels specific sequences in whole chromosomes by in situ DNA chain elongation or PCR (polymerase chain reaction).
In Situ Nick-end Labeling
An in situ method for detecting areas of DNA which are nicked during APOPTOSIS. Terminal deoxynucleotidyl transferase is used to add labeled dUTP, in a template-independent manner, to the 3 prime OH ends of either single- or double-stranded DNA. The terminal deoxynucleotidyl transferase nick end labeling, or TUNEL, assay labels apoptosis on a single-cell level, making it more sensitive than agarose gel electrophoresis for analysis of DNA FRAGMENTATION.
The phase of cell nucleus division following PROPHASE, when the breakdown of the NUCLEAR ENVELOPE occurs and the MITOTIC SPINDLE APPARATUS enters the nuclear region and attaches to the KINETOCHORES.
Techniques for labeling a substance with a stable or radioactive isotope. It is not used for articles involving labeled substances unless the methods of labeling are substantively discussed. Tracers that may be labeled include chemical substances, cells, or microorganisms.
The simultaneous identification of all chromosomes from a cell by fluorescence in situ hybridization (IN SITU HYBRIDIZATION, FLUORESCENCE) with chromosome-specific florescent probes that are discerned by their different emission spectra.
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