Behavior of animal blood in blood typing systems. Isoelectric focusing of erythrocyte acid phosphatase and phosphoglucomutase

Isoenzyme band patterns of animal blood erythrocyte acid phosphatase (EAP) and phosphoglucomutase-1 (PGM) were studied by isoelectric focusing on ultrathin polyacrylamide gels. For blood from all animals tested (dog, cat, cow, sheep, and goat), the overall band patterns for both isoenzymes were different from those of the most common human types of these enzymes, although some animal EAP and PGM bands appeared in the human band areas. When mixtures of human and animal red blood cells were studied, it was found that misinterpretation of human types was possible only if the overall band pattern of the mixtures was ignored. For the animal blood tested, the strong PGM bands appearing outside the human band areas could be used as "markers" for the possible presence of animal blood in the samples tested.     

A novel histological technique for distinguishing between epithelial cells in forensic casework

There are a number of forensic cases in which the identification of the epithelial cell type from which DNA originated would provide important probative evidence. This study aimed to develop a technique using histological staining of fixed cells to distinguish between skin, buccal and vaginal epithelium. First, 11 different stains were screened on formalin-fixed, wax-embedded cells from five women. Samples were analysed qualitatively by examining staining patterns (colour) and morphology (absence or presence of nuclei). Three of the staining methods – Dane's, Csaba's and Ayoub-Shklar – were successful in distinguishing skin epithelial cells from buccal and vaginal. Second, cells were smeared directly onto slides, fixed with one of five fixatives and stained with one of the three stains mentioned above. Methanol fixation, coupled with the Dane's staining method, specific to keratin, was the only technique that distinguished between all three cell types. Skin cells stained magenta, red and orange and lacked nuclei; buccal cells stained predominantly orange–pink with red nuclei; while vaginal cells stained bright orange with orange nuclei and a blue extracellular hue. This staining pattern in vaginal cells was consistent in samples collected from 50 women aged between 18 and 67. Identification of cell type from unlabelled micrographs by 10 trained observers showed a mean success rate of 95%. The results of this study demonstrate that histological staining may provide forensic scientists with a technique for distinguishing between skin, buccal and vaginal epithelial cells and thus would enable more conclusive analyses when investigating sexual assault cases.     

The collation of forensic DNA case data into a multi-dimensional intelligence database

The primary aim of any DNA Database is to link individuals to unsolved offenses and unsolved offenses to each other via DNA profiling. This aim has been successfully realised during the operation of the New Zealand (NZ) DNA Databank over the past five years. The DNA Intelligence Project (DIP), a collaborative project involving NZ forensic and law enforcement agencies, interrogated the forensic case data held on the NZ DNA databank and collated it into a functional intelligence database. This database has been used to identify significant trends which direct Police and forensic personnel towards the most appropriate use of DNA technology. Intelligence is being provided in areas such as the level of usage of DNA techniques in criminal investigation, the relative success of crime scene samples and the geographical distribution of crimes. The DIP has broadened the dimensions of the information offered through the NZ DNA Databank and has furthered the understanding and investigative capability of both Police and forensic scientists. The outcomes of this research fit soundly with the current policies of 'intelligence led policing', which are being adopted by Police jurisdictions locally and overseas.     

Efficacy of Several Candidate Protein Biomarkers in the Differentiation of Vaginal from Buccal Epithelial Cells*

Abstract: Currently, there is no accurate method to differentiate vaginal epithelial cells from buccal epithelial cells in biological samples typically encountered in forensic casework. This study tested the expression of a selection of candidate proteins in buccal and vaginal epithelial cells. We investigated six candidate biomarkers, such as loricrin, vimentin, stratifin, cytokeratin 4, cytokeratin 13, small proline‐rich protein 2, and involucrin, using Western blot analysis on whole protein extracts and immunohistochemistry (IHC) on intact cells in an attempt to identify cell‐specific markers that would differentiate these cells by microscopy. Involucrin, loricrin, and stratifin showed differential expression during Western blot analysis and were carried through to IHC. Although proteins unique to vaginal epithelial cells and buccal epithelial cells were not identified from among the proteins tested, the increased expression levels of two proteins, loricrin and stratifin in vaginal cells, when compared to buccal cells, do provide encouraging results in the search for epithelial cell‐specific markers.     

Development of a one-tube extraction and amplification method for DNA analysis of sperm and epithelial cells recovered from forensic samples by laser microdissection

Laser microdissection can be used in forensic casework to isolate specific cell types from mixtures of biological samples. Extraction of DNA from selected cells is still required prior to STR amplification. Because of the relatively pristine nature of the recovered cells, laser microdissection is more sensitive than more traditional methods of DNA analysis, theoretically resulting in DNA profiles from less cellular material. A one-tube extraction and amplification method minimises loss of DNA through liquid transfers and reduces the potential for contamination events occurring. In this paper, the development of a one-tube method for the effective extraction of DNA from laser microdissected sperm and epithelial cells is described. The performance of the in-house method was compared to that of a commercial DNA extraction kit for extraction of DNA from sperm and the downstream compatibility with STR amplification was determined for both sperm and epithelial samples. Full Identifiler™ profiles after 28 amplification cycles were obtained from as few as 15 epithelial cells and 30 sperm.     

Effects of histological staining on the analysis of human DNA from archived slides

Abstract: Archived slides of cell smears treated with histological stains for sperm detection are often the only source of DNA available when cold cases are reopened. There have been conflicting reports as to the negative effects of particular histological stains on DNA recovery and quality from human cells, making stain selection an important consideration for forensic laboratories. This study investigates the effect of several staining systems on DNA recovery from histological slide samples stored from 0 to 10 weeks. DNA profiles obtained after analysis of these samples with AmpFlSTR^® Identifiler? and increased cycle AmpFlSTR^® SGM Plus? short tandem repeat (STR) profiling systems and the effects that these stains have on DNA quantity and quality over time are described. Results indicate that Christmas Tree and Hematoxylin and Eosin stains do not have significantly different effects on DNA quality after 10‐week storage of slides. This research will assist scientists to select staining systems that have minimal deleterious effects on the DNA recovered.     

Typing of human red cell and serum mixtures in three electrophoretic systems.

The isoenzymes erythrocyte acid phosphatase and phosphoglucomutase were typed in mixed red cell samples which had been derived from two individuals; the protein group specific component was typed in mixed serum samples. Typing was performed by isoelectric focusing on ultrathin polyacrylamide gels. Depending upon the mixture, from 2 to 20% (but typically 5-10%) by volume of a second blood or serum needed to be present in a mixture before it could be detected. In the majority of cases when there was significant mixing, samples were readily identified as a mixture when the results consisted of unusual band patterns or unusual band intensities. There would be a few instances when blood or serum could not be identified as a mixture when masking effects occurred or when the mixture produced a combined, apparently normal, pattern.     

DNA Analysis and Document Examination: The Impact of Each Technique on Respective Analyses

Threatening letters, counterfeit documents, and anonymous notes can commonly be encountered in criminal situations. Such handwritten documents may encourage DNA to transfer from the writer's hands and lower arms when these areas come into contact with the document. As any DNA transferred is likely to be at a low level, sensitive low copy number (LCN) DNA analysis can be employed for testing document exhibits. In this study, we determine locations on the document that are most commonly touched during writing and handling and compare DNA recovery from these sites. We describe the impact of DNA sampling on subsequent document examination techniques including the ESDA^® and likewise the effect of the ESDA^® and two other document examination techniques on subsequent DNA analysis. The findings from this study suggest that DNA results can be obtained through targeted sampling of document evidence, but that care is required when ordering these examination strategies.     

Y STR haplotype data for New Zealand population groups using the Y-Plex 6 kit

Allele and haplotype frequencies were obtained for the six Y STR loci DYS19, DYS389II, DYS390, DYS391, DYS393 and DYS385 in the New Zealand population. Ninety-two different haplotypes were found. The Maori population had a specific haplotype that occurred in over 30% of the population. The Pacific Island population exhibited a triple repeat at the DYS385 locus in 26% of individuals, something rarely observed in other population groups.     

Alleged sexual violation of a human female by a Rottweiler dog.

An unusual case involving the alleged sexual violation of a woman by three men and a Rottweiler dog is described. Forensic examination proved difficult and showed little of evidentiary value but did reveal the presence of dog hairs at the scene, and semen from one of the men on the victim's panties. All attempts to locate and identify dog semen were unsuccessful. It was not clear whether dog semen could not be located using available techniques for semen identification, or whether dog semen was, in fact, not present at all.