Progress in the 16S rRNA Gene Sequencing in Forensic Science / 法医学杂志

Forensic microorganism is one of the hotspots of forensic science research. Due to its conservatism and specificity, the 16S rRNA gene is found to be an ideal marker for forensic identification. With the rapid development of high throughput sequencing technology, the research on microorganisms has been gradually applied to many fields such as environment and health care. In the field of forensic science, the results of forensic microbiology research, represented by 16S rRNA gene sequencing, are also gradually applied to forensic practice, such as biological samples identification, individual identification, postmortem interval estimation, and regional inference, which not only provide clues for the investigation of cases but also complement and assist traditional methods. This paper describes the research methods and related sequencing technologies of 16S rRNA gene sequencing, summarizes its research progress, and discusses the application value and potential of 16S rRNA in forensic science.

Research Progress on Gene Alterations of Amelogenin Locus in Gender Identification / 法医学杂志

There are two kinds of amelogenin gene mutation, including mutation in primer-binding region of amelogenin gene and micro deletion of Y chromosome encompassing amelogenin gene, and the latter is more common. The mechanisms of mutation in primer-binding region of amelogenin gene is nucleotide point mutation and the mechanism of micro deletion of Y chromosome encompassing amelogenin gene maybe non-allelic homologous recombination or non-homologous end-joining. Among the population worldwide, there is a notably higher frequency of amelogenin gene mutations in Indian population, Sri Lanka population and Nepalese population which reside within the Indian subcontinent. Though amelogenin gene mutations have little impact on fertility and phenotype, they might cause incorrect result in gender identification. Using composite-amplification kit which including autosomal STR locus, amelogenin gene locus and multiple Y-STR locus, could avoid wrong gender identification caused by amelogenin gene mutation.

Identification of Vaginal Fluid Using Microbial Signatures / 法医学杂志

OBJECTIVES@#To investigate the specific microbial signatures in vaginal fluid.@*METHODS@#Vaginal fluid （16 samples）, saliva （16 samples）, feces （16 samples）, semen （8 samples）, peripheral blood （8 samples）, urine （5 samples）, and nasal secretion （4 samples） were collected respectively. The 16S rRNA genes of Lactobacillus crispatus, Lactobacillus gasseri, Lactobacillus jensenii, Lactobacillus iners, and Atopobium vaginae were amplified. PCR production was detected via a 3130xl Genetic Analyzer.@*RESULTS@#The detected number of Lactobacillus crispatus, Lactobacillus gasseri, Lactobacillus jensenii, Lactobacillus iners, and Atopobium vaginae were 15, 5, 8, 14, and 3 in all vaginal fluid samples, respectively. Lactobacillus crispatus and Lactobacillus jensenii existed specifically in vaginal fluid.@*CONCLUSIONS@#There is a potential application value to detect Lactobacillus crispatus and Lactobacillus jensenii for the identification of vaginal fluid.

Source Identification of Human Biological Materials and Its Prospect in Forensic Science / 法医学杂志

Source identification of human biological materials in crime scene plays an important role in reconstructing the crime process. Searching specific genetic markers to identify the source of different human biological materials is the emphasis and difficulty of the research work of legal medical experts in recent years. This paper reviews the genetic markers which are used for identifying the source of human biological materials and studied widely, such as DNA methylation, mRNA, microRNA, microflora and protein, etc. By comparing the principles and methods of source identification of human biological materials using different kinds of genetic markers, different source of human biological material owns suitable marker types and can be identified by detecting single genetic marker or combined multiple genetic markers. Though there is no uniform standard and method for identifying the source of human biological materials in forensic laboratories at present, the research and development of a series of mature and reliable methods for distinguishing different human biological materials play the role as forensic evidence which will be the future development direction.

Application of Ion Torrent PGM™ System in Detection of Fetal DNA in Maternal Plasma / 法医学杂志

OBJECTIVE@#To explore the feasibility of detecting of Y-STR of fetal DNA in maternal plasma using Ion Torrent PGM™ System.@*METHODS@#A total of 16 fetal DNA samples from maternal plasmas (8 cases from 38 weeks gestational age and 8 ones from 12 weeks) were prepared and a multiplex assay with 7 STR loci (DYS390, DYS391, DYS393, DYS438, DYS437, DYS456, DYS635) was designed for multiplex-PCR amplification. Using Ion Torrent PGM™ System, the results of Y-STR sequences and capillary electrophoresis were obtained and compared.@*RESULTS@#Y-STR specific alleles were detected in the maternal plasma of all the pregnant women having male babies of second and third trimester, which were higher than that detected by capillary electrophoresis. Consistent Y-STR genotypes were observed between fetal DNA from maternal plasma and genomic DNA from the newborn babies.@*CONCLUSION@#Based on Ion Torrent PGM™ System, the prenatal Y-STR detection method may provide a high-sensitive and high-throughput choice for prenatal STR detection in forensic testing.

Determination of the biological attribute of evidence at the scene using reverse transcription PCR and real-time fluorescent quantitative PCR / 法医学杂志

OBJECTIVE@#To explore the feasibility of biological method to identify the biological attribute of samples at crime scene.@*METHODS@#Thirty samples of ten blood stains, ten saliva stains and ten semen stains were selected, and all the samples were processed by the routine method and biomolecular method, respectively. Both RNA and DNA were isolated using DNA-RNA co-extraction technology and the mRNA was converted into cDNA using reverse transcription PCR (RT-PCR). Three pairs of specific primers were designed for blood stain, saliva stain and semen stain based on the different target genes in three specific tissues and the primers were amplified using real-time fluorescent quantitative PCR. The differences in these biological samples were evaluated by melting temperature (Tm) values and the size of the amplification fragment.@*RESULTS@#The Tm values of blood stain, saliva stain and semen stain were (84.5 +/- 0.2) degrees C, (76.9 +/- 0.3) degrees C and (88.5 +/- 0.2) degrees C, respectively. The length of PCR fragments of them was 177bp, 134bp and 294bp, respectively.@*CONCLUSION@#Compared with the routine method, RT-PCR with real-time fluorescent quantitative PCR is highly specific, sensitive and reliable to identify the biological attribute of evidence, and can be potentially applied to determine evidence attribute in forensic practice.

Forensic application of expressmarker 22 STR loci direct PCR amplification kit / 法医学杂志

OBJECTIVE@#To explore the application value of Expressmarker 22 STR loci direct PCR amplification kit.@*METHODS@#One thousand nine hundred and forty-eight samples (including samples spotted on FTA cards, filter papers and case samples) were tested using Expressmarker 22 STR loci direct PCR amplification kit. At the same time, all were tested using Sinofiler kit, Identifiler kit and PowerPlex 16 kit respectively for comparison. The genotypes were compared at the same STR loci among these four kits to test the sensitivity and accuracy of Expressmarker 22 STR loci direct PCR amplification kit.@*RESULTS@#97.79% samples were successfully typed using Expressmarker 22 STR loci direct PCR amplification kit. The genotype profiles of the same samples using Expressmarker 22 STR loci direct PCR amplification kit were consistent with Sinofiler kit, Identifiler kit and PowerPlex 16 kit at the same STR loci.@*CONCLUSION@#Expressmarker 22 STR loci direct PCR amplification kit can provide huge information and accurate results