Determination of an effective housekeeping gene for the quantification of mRNA for forensic applications

The potential application of mRNA for the identification of biological fluids using molecular techniques has been a recent development in forensic serology. Constitutively expressed housekeeping genes can assess the amount of mRNA recovered from a sample, establish its suitability for downstream applications, and provide a reference point to corroborate the identity of the fluid. qPCR was utilized to compare the expression levels of housekeeping genes from forensic-like body fluid stains to establish the most appropriate assessment of human mRNA quantity prior to profiling. Although variability was observed between fluids and individuals, results indicated that beta-2 microglobulin exhibited the highest expression for all body fluids examined and across donors. A one-way analysis of variance was performed for housekeeping gene variability between donors (at the α, 0.05, significance level), and the results indicated significant differences for semen, vaginal secretions, and menstrual blood.     

Assessment of body fluid identification and DNA profiling after exposure to tropical weather conditions

Despite current advances in body fluid identification, there are few studies evaluating the effect of environmental conditions. The present work assessed the detection of body fluids, blood, semen, and saliva, through lateral flow immunochromatographic (LFI) tests, exposed to tropical weather conditions over time, also evaluating the possibility of obtaining STR (short tandem repeat) profiles and identifying mitochondrial DNA (mtDNA) polymorphisms. Blood, semen, saliva samples, and mixtures of these fluids were deposited on polyester clothes and exposed to open-air tropical weather conditions for 1 month. The test versions from LFI (SERATEC®, Germany) Lab and crime scene (CS) used for the detection – one per each body fluid type – demonstrated that it is possible to identify body fluids and their mixtures up to 14 days after deposition. At 30 days, blood and semen were detected but not saliva. Full STR profiles were obtained from 14-day-old blood samples, and partial profiles were obtained from the remaining samples. It was possible to sequence mtDNA in the samples previously analyzed for STR profiling, and haplogroups could be assigned. In conclusion, this study demonstrated for the first time the possibility of body fluid identification and DNA profiling after exposure to tropical weather conditions for 1 month and also demonstrated the value of mtDNA analysis for compromised biological evidence.     

microRNA Detection in Blood,Urine, Semen,and Saliva Stains After Compromising Treatments

Evaluation of microRNA (miRNA) expression as a potential method for forensic body fluid identification has been the subject of investigation over the past several years. Because of their size and encapsulation within proteins and lipids, miRNAs are inherently less susceptible to degradation than other RNAs. In this work, blood, urine, semen, and saliva were exposed to environmental and chemical conditions mimicking sample compromise at the crime scene. For many treated samples, including 100% of blood samples, miRNAs remained detectable, comparable to the untreated control. Sample degradation varied by body fluid and treatment, with blood remarkably resistant, while semen and saliva are more susceptible to environmental insult. Body fluid identification using relative miRNA expression of blood and semen of the exposed samples was 100% and 94%, respectively. Given the overall robust results herein, the case is strengthened for the use of miRNAs as a molecular method for body fluid identification.     

The Differentiation of Menstrual from Venous Blood and Other Body Fluids on Various Substrates Using ATR FT‐IR Spectroscopy

Crime scene investigators and laboratory analysts use chemical tests to detect and differentiate body fluids. Testing often requires a sample of the stain, and the chemicals may cause degradation of the fluid or interfere with subsequent tests. Colorimetric chemical tests do not differentiate between different types of the same fluid, such as venous and menstrual blood, and there is no presumptive test available to simultaneously differentiate several body fluids. In this study, we recorded ATR FT ‐IR spectra of venous and menstrual blood, semen, saliva, and breastmilk. Neat and simulated casework body fluid samples were analyzed on cotton, nylon, wood, paper, and glass substrates. Differences in fluid composition, including proteins and small molecules, resulted in spectral differences. Venous and menstrual blood is differentiated by the peak at 1039 cm^?1 attributed to phosphoric acid found in menstrual blood. Peak intensity is influenced by the porosity and weave of the substrate fabric.     

An enzyme-linked immunosorbent assay (ELISA) for prostate-specific antigen.

A sandwich ELISA for human prostate-specific antigen (PSA) is described. Optimal assay conditions, resulting in a sensitive assay with a low background, are presented. The method uses a hyperimmune antiserum produced in the New Zealand white rabbit, against human semen PSA. The IgG fraction of the antiserum was conjugated with horseradish peroxidase and used in the sandwich ELISA method. The anti-PSA IgG showed no cross reactions with saliva, normal blood, female urine, vaginal fluid, or menstrual blood. On occasions, a blood sample showed a non-specific cross-reaction, which was detected by non-immune rabbit IgG. This reaction could be caused by rheumatoid factors, as indicated by experiments with a series of known IgG and IgM rheumatoid antibodies, although other heterophilic antibodies could not be eliminated. The recovery of PSA added to blood plasma, saliva and vaginal fluid was affected by three factors; (a) protein concentration (dilution) of body fluid; (b) nature of the protein; and (c) amount of PSA added.     

Screening and identification of tissue-specific methylation for body fluid identification

Identification of body fluid stains can bring important information to crime case. Recent research in epigenome indicates that tissue-specific differentially methylated regions (tDMRs) show different DNA methylation profiles according to the type of cell or tissue, which makes it possible to identify body fluid based on analysis of DNA. This study screened and identified tDMRs from genome for forensic purpose. DNA samples from blood, saliva, semen, and vaginal fluid were analyzed by methylation sensitive represent difference analysis and Sequenom Massarray^® quantitative analysis of methylation. Six blood-specific tDMRs were obtained. Two tDMRs display blood-specific hypomethylation, and four tDMRs show blood-specific hypermethylation. These tDMRs may discriminate blood stain from other body fluids. The result indicated that tDMRs could become potential DNA markers for body fluid identification.     

MMP-11多克隆抗体的制备及其法医学意义

目的制备兔抗人基质金属蛋白酶-11(MMP-11)多克隆抗体,建立用MMP-11抗体检测月经血的可行方法,探讨其法医学意义。方法将用基因工程制备的人MMP-11融合蛋白免疫新西兰白兔,饱和硫酸铵法进行抗体纯化。运用蛋白印迹法检测月经血痕、外周血痕、阴道液斑、精液斑、唾液斑和尿液斑,盲测验证该方法的可靠性。结果高效价的兔抗人MMP-11多克隆抗体检测月经血MMP-11蛋白的阳性率为90.48%(93/105),而外周血痕、精液斑、唾液斑、尿液斑和阴道液斑均未检出MMP-11。结论用自制的抗MMP-11多克隆抗体所建立的蛋白印迹法检测月经血中的MMP-11特异性好,灵敏有效,可用于月经血及外周血的鉴别。     

The use of bacteria for the identification of vaginal secretions

We have used the 16S–23S rRNA intergenic spacer region for identifying vaginal specific bacteria. Lactobacillus crispatus and Lactobacillus gasseri were detected in vaginal secretions but not in semen, blood or saliva. Our data indicated that both L. crispatus and L. gasseri were detected in vaginal secretions from women with different levels of expression of hormonal genes including pregnant, pre- and post-menopausal women, and a woman who has had a hysterectomy. Therefore, we have demonstrated that these Lactobacilli are promising new markers for the forensic identification of vaginal secretions. We have incorporated the Lactobacilli markers into a mRNA multiplex system to produce an 11-plex assay that can identify circulatory blood, menstrual blood, saliva, semen (in the presence and absence of spermatozoa) and vaginal secretions.     

Detection of microRNAs in DNA Extractions for Forensic Biological Source Identification

Molecular‐based approaches for biological source identification are of great interest in the forensic community because of a lack of sensitivity and specificity in current methods. MicroRNAs (miRNAs) have been considered due to their robust nature and tissue specificity; however, analysis requires a separate RNA extraction, requiring an additional step in the forensic analysis workflow. The purpose of this study was to evaluate miRNA detection in blood, semen, and saliva using DNA extraction methods commonly utilized for forensic casework. RT‐qPCR analysis revealed that the tested miRNAs were consistently detectable across most tested DNA extraction methods, but detection was significantly reduced compared to RNA extracts in some biological fluids. DNase treatment was not necessary to achieve miRNA‐specific results. A previously developed miRNA panel for forensic body fluid identification was evaluated using DNA extracts, and largely demonstrated concordance with results from samples deriving from RNA extracts of semen, blood, and saliva.