Forensic serology
Forensic serology is the detection, identification, classification, and study of various bodily fluids such as
Blood detection
Blood is composed of liquid plasma and serum with solid components consisting of red blood cells (
For confirmatory tests, the Takayama Crystal Assay or an
Semen detection
Semen is a colorless fluid that is
Confirmatory tests for semen include the christmas tree stain and the p30/PSA RSID kit. For the christmas tree stain, the sample is extracted with sterile water in order to make a
PSA(p30) is known as a prostate-specific antigen that is produced by the prostatic gland in males.[9] The p30/PSA test is an immunochromatographic test that detects the presence of the antigen p30 in semen samples. This test functions similar to a pregnancy test, where if the antigen p30 is present a band will appear at the test site and a control band will appear to confirm if the test is working properly.[4] If the confirmatory test is positive, then semen is present in the sample. From there an analyst could continue to develop a DNA profile with downstream applications.
Saliva detection
A presumptive test to detect saliva is the alpha-amylase test also known as the Phadebas Test.
For confirmatory tests, there has not been as much research done compared to blood and semen. Since these tests specifically target amylase, confirmatory tests can not be done considering amylase can be found in other bodily fluids.[12]
Urine Detection
The presumptive detection of urine can be done by alternative light sources or a paradimethylaminocinnamaldehyde test (DMAC).[13] The DMAC will react with urea, uric acid or ammonia which can all be found in urine.[13] When a sample with potential urine is found, 0.1% DMAC can be applied. If there is a positive reaction, a pink/magenta colour will be present on the stain.[13] There are only presumptive tests for urine detection because the tests used target material that can be found in other bodily fluids. This can cause a lot of false positives and inaccurate results.[13]
Current research: microRNA
Testing for different body fluids with traditional serological techniques, such as those listed above, is possible, but not without some drawbacks. Firstly, not all body fluids have a reliable confirmatory test, and those that do typically require a larger amount of the suspected stain in order to perform the confirmatory test. This can be limiting if the forensic sample being tested is small to begin with. Also, serology is often done before any downstream analyses like DNA, so if sample is limited in size to begin with performing serological analyses and obtaining a DNA profile successfully may not be possible. Currently, researchers are looking into ways to identify bodily fluids with more success and less sample needed, and an emerging way to do this is with micro RNAs.
Micro RNAs (
miRNA can be extracted using a number of commercially available kits, such as the Solid Phase QIAmp DNA mini kit.
Current potential miRNA biomarkers: Research is still needed in order to narrow down potential biomarkers, as some tissues and fluids have the same miRNA expressed in different concentrations. To date, blood and semen miRNAs have been the most studied and have found promising candidate biomarkers.
Bodily Fluid | Potential Biomarkers for ID[17] |
---|---|
Blood | miR451, miR16 |
Semen | miR135b, miR10b |
Saliva | miR658, miR205 |
Vaginal Secretions | miR124a miR372 |
Menstrual Blood | miR412 with miR451 |
Current research: Loop-mediated isothermal amplification
Like the technique of extracting miRNA, researchers have been able to test one or more samples by extracting DNA and testing it in an instrument that most labs have readily available. This method has proven to produce more DNA than PCR based amplification. Researchers have also added other factors to the loop-mediated isothermal amplification make identification of different body fluids. Using LAMP has reduced the time needed to get results, which is what the ultimate goal was. Although it has proven to decrease total and hands-on time needed to get a result, there are still kinks to work out before this method is used in many or all forensic labs.
See also
References
- ISBN 0-7637-5522-2
- ^ Fundamentals of Forensic Science By Max M. Houck, Jay A. Siegel p. 229 Publisher: Academic Press; 2 edition (February 3, 2010)
Language: English ISBN 0-12-374989-1
- ^ a b c d e f g "Forensic Resources". www.ncids.com. Retrieved 2018-10-25.
- ^ ISBN 9781493300204.
- ^ a b "10.1: Blood detection using the Kastle-Meyer test". Biology LibreTexts. 2019-06-30. Retrieved 2022-03-16.
- ^ "Science Fair Project Ideas". Science Buddies. Retrieved 2018-10-25.
- ^ a b "Search Results | Forensic Supplies, m7". CSI Forensic Supply. Retrieved 2022-03-16.
- ^ a b c Gaensslen, R.E. (August 1983). "Sourcebook in Forensic Serology, Immunology, and Biochemistry" (PDF). U.S. Department of Justice.
- ^ CiteSeerX 10.1.1.618.2623.
- ISBN 9780128151457, retrieved 2022-03-16
- PMID 27640169.
- ISBN 9780470018262, retrieved 2022-03-16
- ^ PMID 22583500.
- ^ a b Courts, C., Madea, B. (2010). Micro-rna- a potential for forensic science. Forensic Science International. 203; 106-111
- ^ a b c Meer, D., Uchimoto, M., Williams,G.(2013). Simultaneous analysis of micro-RNA and DNA for determining the body fluid origin of DNA profiles. Journal of Forensic Sciences. 58,4; 967-971
- ^ Tong D, Jin Y, Xue T, Ma X, Zhang J, Ou X, et al. (2015) Investigation of the Application of miR10b and miR135b in the Identification of Semen Stains. PLoS ONE 10(9): e0137067. doi:10.1371/ journal.pone.0137067
- ^ Hanson, E.K., Lubenow, H., Ballantyne, J. (2009). Identification of forensically relevant body fluids using a panel of differentially expressed microRNAs. Analytical Biochemistry.387, 303-314.