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Journal of medical entomology, 55, 575--586

Description of Larval Instars To Fill a Gap in Forensic Entomology: The Larvae of Paralucilia pseudolyrcea (Diptera: Calliphoridae).

Da Silva, S M, Vairo, K P, Moura, M O

A fundamental assumption of forensic entomology for estimating the postmortem interval is that insect species are accurately identified, which depends on diagnostic morphological characters. Larvae of the blow fly Paralucilia pseudolyrcea (Mello, 1969) (Diptera: Calliphoridae) were sampled from four corpses in the state of Paraná, Brazil, but despite the forensic importance of this species, morphological data for the identification of its larval instars are lacking, limiting its usefulness in such cases. Thus, the main goal of this study was to describe the larval instars of P. pseudolyrcea. The material was obtained from a colony established by larvae collected from a corpse of a murder case. Overall, the distribution of spines is a key character for identifying this species in the first, second and third instars. Other characteristics, such as the presence of an accessory oral sclerite, the small cirri, the number of lobes of the anterior spiracle and the morphology of posterior spiracles, separates P. pseudolyrcea from other necrophagous blow flies. The detailed morphological description provided here facilitates the identification of larval instars of P. pseudolyrcea and their differentiation from those of other calliphorid species.

Digital object identifier (DOI): 10.1093/jme/tjx257

Forensic Science International: Genetics Supplement Series, 3(1), e35-e36

Automated scoring of Sperm Hy-Liter™-stained spermatozoa by the MetaSystems Metafer image analysis software system in sexual assault specimens

De Moors, A., Fr{\'e}geau, C.J.

The MetaSystems Metafer image analysis software system was purchased three years ago in the hope of developing a routine approach in the RCMP Forensic Laboratories to automate the scoring of human spermatozoa in sexual assault exhibits. This would enhance case throughput, increase assay sensitivity and standardize the search for spermatozoa. The development of appropriate classifiers was challenging but essential to teach the software system to specifically recognize human spermatozoa fluorescently stained using the Sperm Hy-Liter™ kit (Independent Forensics). Optimized classifiers were tested/validated using a diverse set of slides prepared from mock sexual assault samples containing a limited or a large number of spermatozoa (fecal swabs, vaginal swabs, all mixed with different semen dilutions in addition to urine, blood and yeasts for a subset of those swabs). The performance of Metafer was recorded with respect to false positive counts, false negative counts and time required for the detection of spermatozoa in each sample. Automated spermatozoa counts were further compared to manual spermatozoa scoring in addition to comparing the time spent executing the identification. An excellent concordance was noted between automated and manual counts. The results of this study indicate that automated scoring of fluorescently stained spermatozoa in mock sexual assault exhibits can be carried out reliably and reproducibly using well-developed classifiers for the MetaSystems Metafer image analysis software system. The automated scoring of spermatozoa combining Sperm Hy-Liter™/MetaSystems Metafer will be tested on a large number of sexual assault cases as part of a pilot project within an operational setting.

Int J Legal Med, 124(6), 513--521
November, 2010

Laser capture microdissection in forensic research: a review.

Mado Vandewoestyne, Dieter Deforce

In forensic sciences, short tandem repeat (STR) analysis has become the prime tool for DNA-based identification of the donor(s) of biological stains and/or traces. Many traces, however, contain cells and, hence, DNA, from more than a single individual, giving rise to mixed genotypes and the subsequent difficulties in interpreting the results. An even more challenging situation occurs when cells of a victim are much more abundant than the cells of the perpetrator. Therefore, the forensic community seeks to improve cell-separation methods in order to generate single-donor cell populations from a mixed trace in order to facilitate DNA typing and identification. Laser capture microdissection (LCM) offers a valuable tool for precise separation of specific cells. This review summarises all possible forensic applications of LCM, gives an overview of the staining and detection options, including automated detection and retrieval of cells of interest, and reviews the DNA extraction protocols compatible with LCM of cells from forensic samples.