Toward Analysis at the Point of Need: A Digital Microfluidic Approach to Processing Multi-Source Sexual Assault Samples.

Forensic case samples collected in sexual assaults typically contain DNA from multiple sources, which complicates short-tandem repeat (STR) profiling. These samples are typically sent to a laboratory to separate the DNA from sperm and non-sperm sources prior to analysis. Here, the automation and miniaturization of these steps using digital microfluidics (DMF) is reported, which may eventually enable processing sexual assault samples outside of the laboratory, at the point of need.

Differentiation of vaginal cells from epidermal cells using morphological and autofluorescence properties: Implications for sexual assault casework involving digital penetration.

Analysis of DNA mixtures from sexual assault evidence is an ongoing challenge for DNA casework laboratories. To assist the forensic scientist address source and activity level propositions there is a significant need for new techniques that can provide information as to the source of DNA, particularly for sexual assault samples that do not involve semen. The goal of this study was to develop a new biological signature system that provides additional probative value to samples comprised of mixtures of epidermal and vaginal cells, as may be observed in cases involving digital penetration.

Differentiation of vaginal cells from epidermal cells using morphological and autofluorescence properties: Implications for sexual assault casework involving digital penetration.

Analysis of DNA mixtures from sexual assault evidence is an ongoing challenge for DNA casework laboratories. There is a significant need for new techniques that can provide information as to the source of DNA, particularly for sexual assault samples that do not involve semen. The goal of this study was to develop a new biological signature system that provides additional probative value to samples comprised of mixtures of epidermal and vaginal cells, as may be observed in cases involving digital penetration.

Transfer and persistence of DNA on items routinely encountered in forensic casework following habitual and short-duration one-time use.

Empirical data obtained from controlled experiments is necessary to ensure that sound expert opinion evidence is provided regarding transfer and persistence of DNA in criminal proceedings. Knowledge in this area is also required at the outset of criminal investigations, to ensure that the proposed examinations can assist with answering questions that are relevant to forensic investigations. This study aimed to provide such data by examining the relative and absolute quantities of DNA deposited on items that are routinely submitted to the forensic laboratory by a habitual user, defined as someone who used it for ~1 week, and a subsequent one-time user.

Case study: Loss of Kastle-Meyer test specificity on jeans.

A pair of jeans produced false positive results upon testing for the presence of blood using the Kastle-Meyer (KM) test. Positive reactions were obtained from all unstained areas of the fabric tested. The peroxidase used in the manufacture of some jeans may be the causative agent for the observed false positive reactions; however, it was not possible to confirm this theory.

Implementing a biogeographic ancestry inference service for forensic casework.

The Centre of Forensic Sciences has validated the Precision ID Ancestry Panel on the Ion S5™ Massively Parallel Sequencing instrument for use in forensic casework. The focus of this paper is the development of reporting guidelines for implementation of the biogeographic ancestry inference service based on the Admixture Prediction results produced using the Torrent Suite™ Software (Thermo Fisher Scientific). The Admixture Prediction algorithm estimates the genetic ancestry of a sample using seven root populations (Europe, East Asia, Oceania, America, Africa, South Asia, and Southwest Asia).

Inferring the presence of spermatozoa in forensic samples based on male DNA fractionation following differential extraction.

To address sexual assault kit backlogs some laboratories in North America have implemented 'Direct to DNA' (DTD) approaches for the examination of relevant vaginal, oral, rectal and external genitalia swabs from sexual assault examination kits. Using this approach no preliminary serological screening for semen or spermatozoa is performed. Instead, swabs are directly subjected to differential extraction and quantitation using a dual quantification system.

Kastle-Meyer blood test reagents are deleterious to DNA.

The Kastle-Meyer (KM) test is a quick and easy chemical test for blood used in forensic analyses. Two practical variations of this test are the KM-rub (indirect) test and the more sensitive KM-direct test, the latter of which is performed by applying reagents directly to a suspected blood stain. This study found that sodium hydroxide present in the KM reagents eliminated the potential to generate a DNA profile when applied directly to small quantities of blood.

First all-in-one diagnostic tool for DNA intelligence: genome-wide inference of biogeographic ancestry, appearance, relatedness, and sex with the Identitas v1 Forensic Chip.

When a forensic DNA sample cannot be associated directly with a previously genotyped reference sample by standard short tandem repeat profiling, the investigation required for identifying perpetrators, victims, or missing persons can be both costly and time consuming. Here, we describe the outcome of a collaborative study using the Identitas Version 1 (v1) Forensic Chip, the first commercially available all-in-one tool dedicated to the concept of developing intelligence leads based on DNA. The chip allows parallel interrogation of 201,173 genome-wide autosomal, X-chromosomal, Y-chromosomal, and mitochondrial single nucleotide polymorphisms for inference of biogeographic ancestry, appearance, relatedness, and sex.

CDK activity antagonizes Whi5, an inhibitor of G1/S transcription in yeast.

Cyclin-dependent kinase (CDK) activity initiates the eukaryotic cell division cycle by turning on a suite of gene expression in late G1 phase. In metazoans, CDK-dependent phosphorylation of the retinoblastoma tumor suppressor protein (Rb) alleviates repression of E2F and thereby activates G1/S transcription. However, in yeast, an analogous G1 phase target of CDK activity has remained elusive.

Yeast functional genomics and cell biology: no longer in the dark.

A report on the Cold Spring Harbor Laboratory meeting 'Yeast Cell Biology', Cold Spring Harbor, USA, 12-17 August 2003.