Diatom extraction: A new technique with heated H2O2. A technical note

The best method of diatom identification in animal and human tissues is still an important discussion topic, in terms of effectiveness and reliability. In this technical note, authors propose a new method of extraction of diatoms using heated hydrogen peroxide from animal and human tissue samples. This method has been compared with the traditional method of digestion with acids. The results of the comparison show that heated hydrogen peroxide extraction is more efficient in terms of reduction of sediment, extraction of the material and preservation of diatoms proving to be a viable alternative to conventional approaches with acids in terms of costs and operator safety.     

The number of SNPs required for distinguishing Japanese from other East Asians

In some cases, it is necessary to estimate the national origin of an unknown subject in forensic medicine. The use of single nucleotide polymorphism (SNP) markers appears to be very effective for this purpose, since genome-wide SNP genotype data of many human populations are publicly available. In this study, we examined the number of SNPs that could objectively and accurately distinguish Japanese subjects (1KG-JPT) from the other East Asians (1KG-CDX, -CHB, -CHS, and -KHV) using the combination of principal component analysis and hierarchical cluster analysis. A computer simulation showed that approximately 3000 randomly selected SNPs were enough for the discrimination. Our results suggest that at least a 0.024% coverage is needed in the next generation sequencing experiment to objectively determine whether an unknown person is Japanese or not if the amount of DNA sample from him/her is insufficient or the quality is low.     

Application of nasal profile estimation methods for Korean population

The nose is an important facial feature that affects facial reconstruction quality and its recognition. We reviewed a selection of papers that researched the nose with regression analysis and applied their regression formulae to our sample to compare the estimated value and measurements. One-hundred computed tomography (CT) scans of Korean adults were selected for this study. The subjects were patients without head trauma, severe deformities, or asymmetry at St. Mary’s Hospital in Seoul, Korea. Three dimensional (3D) models of the cranium and face were remodelled and measured by Mimics 14.1 (Leuven, Belgium, Materialise). A measurement system for 3D models that referred to landmarks from previous studies was used to facilitate the comparison process. Estimation formulae were applied to the subjects and compared with the measurement results of this study’s population. Corresponding measurements showed that the measurements were statistically significantly different from estimated values obtained with regression formulae. A difference in the results was expected because of the different sample population, but the age of subjects could also impact the results and cause variability. Therefore, the results of this study emphasise the necessity of basal research for a specific target population.     

Sensitive quantitative analysis of psilocin and psilocybin in hair samples from suspected users and their distribution in seized hallucinogenic mushrooms

Forensic Toxicology - In this study, we developed a very sensitive method for quantitative analysis of psilocin and psilocybin in hair samples of magic mushroom consumers. The analyses were...     

Advantages of filtration method for sperm-DNA genotyping in sexual assault cases

Differential extraction (DE) is a conventional method to isolate sperms from forensic semen samples (e.g. vaginal swab containing semen) for sperm-DNA genotyping. Subsequent to selective digestion of somatic cells in a mixture sample, sperms are collected and purified as a pellet by repetitive centrifugation based on the specific gravity of sperm heads. However, the centrifugation operation requires a technical proficiency and an extensive time to prevent a loss of sperms from the pellet as much as possible. Therefore, we devised a “filtration method (FM)”, in which a vacuum filtration operation based on the size of sperm heads is adapted, instead of DE, for isolation of sperms without any loss in principle. Sperms are collected and purified on a polycarbonate membrane filter. In this study, we have compared results of forensic assays by DE and FM for sperm-DNA genotyping from forensic semen samples. Consequently, FM had advantages of easy operation, timesaving, and high yield of sperms from semen samples compared with DE, although FM had a comparable ability to DE for a purification of sperms from mixture samples. Thus, we present that FM could simply lead to success of sperm-DNA genotyping and has a possibility to supersede DE as a gold-standard method.     

Increase expression of α-synuclein in aged human brain associated with neuromelanin accumulation

Although the increased prevalence of Parkinson’s disease (PD) with aging suggests that aging processes predispose dopamine neurons to degeneration, the mechanism involved remains unknown. Dopamine neurons contain significant amounts of neuromelanin, and the amount of neuromelanin increases with aging. In the present study, age-related changes in the number of nigral neurons expressing neuromelanin (NM), α-synuclein, and tyrosine hydroxylase (TH) were stereologically analyzed in the postmortem brains of 28 healthy humans with an age range of 17–84 years. Stereological counting of NM content, α-synuclein content, and TH immunoreactivity revealed significant accumulation of NM and α-synuclein in neurons during the aging process. In cells containing a large amount of NM, α-synuclein-immunoreactive cells in aged individuals outnumbered those of younger individuals. In non-NM cells, the α-synuclein expression profile was similar across age groups. Furthermore, TH-immunoreactive neurons decreased significantly with aging, which was associated with accumulation of NM and α-synuclein. Our results suggest that age related accumulation of NM might induce α-synuclein over-expression and thereby make dopamine neurons more vulnerable to injuries.     

Pedigree likelihood formulae based on founder and founder couple symmetry and validation of DNA testing software

Pedigree likelihood ratios are widely used in forensic genetics. Linkage of genetic markers affects the pedigree likelihood ratio. In this study, a series of novel formulae was established based on simplification due to founder and founder couple symmetry of the Lander-Green algorithm for dealing with linkage. These new formulae are based on the inheritance vectors and differ from existing formulae that are based on the number of alleles shared identical-by-descent. In contrast to previous formulae, the formulae of this study expand the calculation to more general relationships, which enables specifying the number of typed individuals in pedigrees, and the new formulae are no longer limited to calculation of pairs of linked markers. Alternatively, pedigree likelihood values incorporating multiple linked markers could be obtained by iterating the vector transition probability between pairs of linkage markers and the probability of genotypes of typed individuals given inheritance vectors; the vector transition probability formulae are provided in a table form. To demonstrate utilization of the proposed formulae system, a series of cases were designed based on the relationships to validate GeneVisa software (www.genevisa.net) with frequency data of three linked markers, SE33-D6S1043-D6S474, on chromosome 6. The calculation results were verified with the FamLink software. The results demonstrated that the proposed formulae can correctly obtain the pedigree likelihood ratio, demonstrating the application potential of these formulae to verify effectiveness of DNA testing software.     

Kinship analysis of skeletal remains from the Middle Ages

Medieval cemeteries Klisa-Guca Gora, Alihodze and Glavica-Han Bila located in the Travnik area (Travnik, Bosnia and Herzegovina) were archaeologically examined in the period 2011–2014, revealing human skeletal remains of 11 individuals in total. Archaeological skeletal samples, previously deposited in Travnik Homeland Museum (Travnik, Bosnia and Herzegovina) were subjected to genetic analysis. The aim of this research was to test familiar relationship of 11 individuals excavated from three medieval cemeteries and to predict Y-haplogroup for male individuals. In order to perform molecular-genetic characterisation of collected human skeletal remains, two systems of genetic markers were analysed: autosomal and Y-STR loci. Complete or partial data obtained by autosomal STR typing of 11 individuals were subjected to kinship analysis. Male sex was determined in eight samples out of 11. Direct relatives of the "brother-brother" type were detected in one case with high kinship probability (KP) value of 99.99996 %. Complete or nearly complete and usable Y-STR profiles were obtained for six out of eight male individuals. The presence of identical haplotypes at Y-STR loci and results of Y-haplogroup prediction suggest that all male individuals share the same paternal lineage and belong to J2a haplogroup. Overall, this study emphasises the usefulness, efficiency and sensitivity of STR markers in the molecular-genetic characterisation of old skeletal remains as well as the importance of employing additional markers like Y-STRs in archaeogenetic studies, besides traditionally used autosomal STR markers, in order to get a comprehensive information about close and distant relatives, and ancestry.