Forensic entomology when the evidence is "no insect." Best carrion fly species for predicting maximum postmortem interval in the United Arab Emirates

The carrion insect species that most quickly deposit offspring on a corpse are, when available, likely to yield a more useful estimate of postmortem interval (PMI) compared to later arrivals. This is in part because the age of the oldest larva will be as close as possible to the PMI when doing a development analysis, and because the preappearance interval (PAI), the time the corpse was exposed before insect colonization, corresponds to the narrowest window of time since death for an insect-free corpse when doing a succession analysis. Given replicated training data a prediction of exposure time for a corpse can be in the form of a confidence set, and the maximum value of that set for an insect-free corpse is a probabilistic version of PAI. To discover the insect species likely to be useful in the early postmortem period in the United Arab Emirates we exposed 216 rat carcasses outdoors at two sites in Dubai over three-day periods during winter. Rats were sampled twice each day without replacement and kept in the lab to allow carrion insects to complete development to the adult stage. The fly species produced in this way were Sarcophaga dux, S. ruficornis, Wohlfahrtia nuba, W. indigens (Sarcophagidae), Chrysomya albiceps (Calliphoridae), and Musca domestica (Muscidae). To the best of our knowledge this is the first record of W. indigens larvae feeding on carrion. While adult C. albiceps and M. domestica were abundant on the carcasses, C. albiceps colonized too slowly to be useful for this type of succession analysis within this time frame, and M. domestica emerged from a single rat. The Sarcophagidae were rapid colonizers, and under these conditions the probability is>90% that a carcass would remain free of S. dux larvae not more than 57 h and free of W. nuba larvae for not more than 51 h.

Abstract P5-04-08: Timing provides context for the paradoxical effects of AMPK activation in ER+ breast cancer: Suppressing growing tumors, but promoting dormant tumor cell survival and recurrence

Precision oncology requires delivering the right drug to the right patient at the right time, but “time” is rarely studied preclinically before a drug enters a particular clinical setting. Despite showing efficacy against recurrent/metastatic solid tumors, drugs sometimes fail to prevent tumor recurrence when given (neo)adjuvantly. The biology and microenvironments of overt tumors likely differ substantially from dormant cancer cells. The development of preclinical models to investigate clinically dormant disease will increase understanding of residual tumor cell biology and enable the development of therapeutics for rational adjuvant trials.

Despite treatment with adjuvant anti-estrogen therapies, ˜30% of patients with ER+ breast cancer (BC) experience recurrence. In contrast to other BC subtypes, ER+ relapses occur late, often appearing years to decades after initial diagnosis and treatment. This delay suggests that ER+ BC cells can undergo extended periods of clinical dormancy. We developed novel, clinically relevant xenograft models of dormancy in ER+ BC. Low systemic levels of estrogens in mice can be further suppressed by ovariectomy, mimicking the effects of aromatase inhibitor (AI)-induced estrogen deprivation (ED) therapy. In ovariectomized mice, luciferase-labeled MCF-7, HCC-1428, HCC-1500, and MDA-MB-415 cells, as well as the HCI-017 PDX model, formed palpable orthotopic tumors upon 17b-estradiol supplementation. ED induced rapid tumor regression and decreased bioluminescent signal. However, a small proportion of ER+ BC cells survived ED for >1 year in a clinically dormant, growth-suppressed state. This residual cell population stabilized after ˜90 days of ED, as evidenced by stabilization of bioluminescent signal. Transcriptional and immunohistochemical analyses revealed significant upregulation of AMP-activated protein kinase (AMPK)-alpha-2 levels and activity in clinically dormant tumor cells compared to estrogen-driven or acutely ED xenografts. Dormant tumor cells were dependent upon AMPK activity for survival, as short-term pharmacologic inhibition of AMPK reduced residual bioluminescent signal.

Metformin is an AMPK-activating drug approved for the treatment of diabetes. Metformin is currently being tested as an anti-cancer agent in many clinical trials at various points in the disease progression of diverse cancer types. In our models of clinically dormant ER+ BC, AMPK activation via metformin slowed ED-induced tumor regression, promoted residual tumor cell survival, and caused earlier tumor regrowth. In vitro studies indicated that metformin promotes cell survival during ED by enhancing fatty acid β-oxidation. Conversely, metformin treatment slowed estrogen-driven tumor growth, in agreement with prior observations that metformin slows growth of various tumor subtypes. These findings suggest that AMPK activation may be efficacious against growing tumors, but deleterious when used in combination with drugs that suppress tumor growth and induce regression. More broadly, this work highlights the issue that the time in a disease course needs to be considered when testing potential anti-cancer agents such as AMPK modulators.

Citation Format: Miller TW, Hampsch RA, McCleery CF, Wells JD, Fields JL, Dillon LM, Shee K. Timing provides context for the paradoxical effects of AMPK activation in ER+ breast cancer: Suppressing growing tumors, but promoting dormant tumor cell survival and recurrence [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-04-08.

Abstract P3-11-15: Development of pan-cancer transcriptional signatures that predict chemosensitivity

Background: Despite the increasing understanding of the molecular characteristics of cancer, chemotherapy success rates remain low for many cancer types. Studies have attempted to identify patient and tumor characteristics that predict sensitivity or resistance to different types of conventional chemotherapies, yet a concise model that predicts chemosensitivity based on gene expression signatures across cancer types remains to be formulated. We attempted to generate a pan-cancer chemosensitivity predictive model using publicly available data from multiple sources. Such a model may increase the likelihood of identifying the type of chemotherapy most likely to succeed for a given patient based on the gene expression signature of their tumor.

Methods: Data used to build the predictive model were obtained from the Genomics of Drug Sensitivity in Cancer (GDSC) database, consisting of gene expression profiles from 962 cancer cell lines via RNA sequencing (RNA-seq) and drug sensitivity profiles reported as ln(IC50). Predictive gene signatures were generated using a cross-validated generalized linear model (leave one out cross-validation) using elasticnet penalization parameters. Models were generated for each individual drug tested by the GDSC cohort, as well as different classes of chemotherapeutics (platinum agents, topoisomerase inhibitors, mustard agents, antibiotics and anti-fungals, anti-metabolites, and taxanes). Accuracy of the models was determined using normalized mean square error (nRMSE). Models were then validated using publicly available data from Cancer Cell Line Encyclopedia (CCLE), NCI-60, and the Patient-Derived Xenograft (PDX) Clinical Trial (PCT) database. Models were further validated using human tumor datasets available via the Gene Expression Omnibus (GEO). As the training data used to generate the models were from RNA-seq, and some of the testing and validation data were generated using microarray technology, feature-specific quantile normalization was used to enable cross-platform analyses.

Results: For most single-drug gene signatures, accuracy measured by nRMSE ranged from 0.10-0.20, which suggests that for any given model the root mean squared error is 10-20% of the range of actual ln(IC50) in the tested data. Chemotherapy class-level models yielded slightly less accuracy, with nRMSE ranging from 0.15-0.25 for most classes. When considering how well the models predicted chemosensitivity within cancer types, accuracy was improved in some cancer types (e.g., lung cancer and head and neck cancer), with more heterogeneous cancer types (e.g., breast cancer) giving less accuracy.

Conclusions: Our results show that the models generated can predict chemosensitivity across cancer types with clinical useful levels of accuracy, with some cancer types resulting in a high rate of accuracy across several classes of chemotherapy. The inclusion of future datasets, particularly from those cancer types in which chemosensitivity has been difficult to predict, may provide opportunities to strengthen model accuracy as well as decrease the numbers of genes needed to assess chemosensitivity.

Citation Format: Wells JD, Miller TW. Development of pan-cancer transcriptional signatures that predict chemosensitivity [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-11-15.

Amplified fragment length polymorphism analysis supports the valid separate species status of Lucilia caesar and L. illustris (Diptera: Calliphoridae)

Common DNA-based species determination methods fail to distinguish some blow flies in the forensically and medically important genus Lucilia Robineau-Desvoidy. This is a practical problem, and it has also been interpreted as casting doubt on the validity of some morphologically defined species. An example is Lucilia illustris and L. caesar, which co-occur in Europe whilst only L. illustris has been collected in North America. Reports that these species shared both mitochondrial and nuclear gene sequences, along with claims that diagnostic morphological characters are difficult to interpret, were used to question their separate species status. We report here that amplified fragment length polymorphism profiles strongly support the validity of both species based on both assignment and phylogenetic analysis, and that traditional identification criteria based on male and female genital morphology are more reliable than has been claimed.

Isolation of the Male-Specific Transformer Exon as a Method for Immature Specimen Sex Identification in Chrysomya megacephala (Diptera: Calliphoridae)

Being able to efficiently differentiate between male and female individuals in the immature forms of insects allows for investigations into sexually dimorphic patterns of growth rates and gene expression. For species lacking sex-specific morphological characteristics during these periods, alternative methods must be devised. Commonly, isolation of sex determination genes reveals sex-specific band patterns and allows for markers that can be used in insect control. For blow flies, a family that includes flies of medical and forensic importance, sex has previously been identified in some members using the male-specific exon in the transformer gene. This gene is relatively conserved between members of the genera Cochliomyia and Lucilia (Diptera: Calliphoridae), and we isolated a portion of this gene in an additional forensically and medically important blow fly genus using the widespread Chrysomya megacephala (F.). We found a relatively high level of conservation between exons 1 and 2 of transformer and were able to amplify a region containing the male-specific exon in C. megacephala. A sex-specific molecular diagnostic test based on the presence of sexually dimorphic PCR product bands showed the expected genotype for adults and intrapuparial period specimens of known sex. The same result could be obtained from single third-instar larval specimens, opening up the possibility to not only determine if development rates are sex dependent, but also to investigate the development of sexually dimorphic traits of interest in C. megacephala.

The forensically important blow fly, Chrysomya megacephala (Diptera: Calliphoridae), is more likely to walk than fly to carrion at low light levels

One factor that influences estimates of time since death using entomological evidence is whether or not blow flies nocturnally oviposit. Field studies focusing on egg laying have found it occurs on an inconsistent basis. A key but poorly understood factor in nocturnal oviposition is a blow fly's ability to locate carrion under low light levels. It has been speculated that blow flies are more likely to walk than fly to carrion during the night, but this has not been empirically tested. We directly compared guided walking versus flying using infrared sensors under low light levels in laboratory conditions for Chrysomya megacephala (F.) (Diptera: Calliphoridae), a blow fly previously described to be nocturnal. We found C. megacephala is more likely to walk than fly toward carrion under low light levels (p=0.016). We did not, however, find differences between males and females for walking (p=0.48) or flying (p=0.42) despite male C. megacephala possessing eyes better suited for increased light capture. These results demonstrate the need to better understand where blow flies go at night, as bodies found within a fly's walking distance are more likely to be colonized.

Body Size, Rather Than Male Eye Allometry, Explains Chrysomya megacephala (Diptera: Calliphoridae) Activity in Low Light

Male Chrysomya megacephala (F.) blow fly compound eyes contain an unusual area of enlarged dorsal facets believed to allow for increased light capture. This region is absent in females and has been hypothesized to aid in mate tracking in low light conditions or at greater distances. Many traits used in the attraction and capture of mates are allometric, growing at different rates relative to body size. Previous reports concerning C. megacephala eye properties did not include measurements of body size, making the relationship between the specialized eye region and body size unclear. We examined different morphological features of the eye among individuals of varying sizes. We found total eye size scaled proportionately to body size, but the number of enlarged dorsal facets increased as body size increased. This demonstrated that larger males have an eye that is morphologically different than smaller males. On the basis of external morphology, we hypothesized that since larger males have larger and a greater number of dorsally enlarged facets, and these facets are believed to allow for increased light capture, larger males would be active in lower light levels than smaller males and females of equal size. In a laboratory setting, larger males were observed to become active earlier in the morning than smaller males, although they did not remain active later in the evening. However, females followed the same pattern at similar light levels suggesting that overall body size rather than specialized male eye morphology is responsible for increased activity under low light conditions.

Verification of AFLP kinship methods of entomological evidence by sequencing

Kinship analysis allows the determination of sibship based on the individuals' genetic profile. In a recent empirical study, amplified fragment length polymorphism (AFLP) analysis was proposed as a test to determine kinship between Phormia regina individuals useful in inferring postmortem transport of a corpse. In order to validate this technique, mitochondrial DNA gene cytochrome oxidase II was sequenced for all individuals used in the previous study. Then, the relatedness coefficient based on AFLP profiles was determined for the pairs of individuals that had different haplotypes, and thus could not be full siblings, to determine a conservative false positive error rate of this proposed test. A majority, 96%, of pair wise comparisons of individuals with different haplotypes had relatedness coefficients <0.41 supporting the conclusion that AFLP analysis for full sibship is a valid and robust technique and thus useful for the detection of postmortem movement of a corpse.

Population genetic structure of an invasive forensically important insect

The forensic utility of an insect can depend in part on its population structure. Although some native North American species have been characterized in this fashion, information is lacking for species that were introduced from elsewhere and that might have lower genetic diversity and less geographic differentiation. We surveyed Chrysomya megacephala, an Asian fly present in the continental USA since the 1980s. Amplified Fragment Length Polymorphism profiles were generated from adult insects collected across Florida and in Mobile, Alabama. Analysis of Molecular Variance on 151 polymorphic loci found significant but very small variation among samples. STRUCTURE and principal coordinate analyses produced the same two clusters in the population, consistent with C. megacephala in Florida having originated from two separate source populations. A weak negative correlation between genetic and geographic distances probably reflected the geographic arrangement of the genetic clusters. A positive relative relatedness coefficient for each sample indicated that flies arriving at a bait within a short time were likely to be close relatives, consistent with the earlier results for native North American carrion flies. However, genetic diversity estimated for the introduced Florida C. megacephala was lower than for native species or for published data on Malaysian C. megacephala, perhaps reflecting the genetic effects of being introduced to a new geographic region. Genetic assignment, a method that has been proposed as a way to infer corpse postmortem relocation, was much less successful for C. megacephala compared to the native species, possibly reflecting a history of admixture.

An evaluation of sampling methods used to produce insect growth models for postmortem interval estimation

Many authors produced carrion insect development data for predicting the age of an insect from a corpse. Under some circumstances, this age value is a minimum postmortem interval. There are no standard protocols for such experiments, and the literature includes a variety of sampling methods. To our knowledge, there has been no investigation of how the choice of sampling method can be expected to influence the performance of the resulting predictive model. We calculated 95 % inverse prediction confidence limits for growth curves of the forensically important carrion flies Chrysomya megacephala and Sarconesia chlorogaster (Calliphoridae) at a constant temperature. Confidence limits constructed on data for entire age cohorts were considered to be the most realistic and were used to judge the effect of various subsampling schemes from the literature. Random subsamples yielded predictive models very similar to those of the complete data. Because taking genuinely random subsamples would require a great deal of effort, we imagine that it would be worthwhile only if the larval measurement technique were especially slow and/or expensive. However, although some authors claimed to use random samples, their published methods suggest otherwise. Subsampling the largest larvae produced a predictive model that performed poorly, with confidence intervals about an estimate of age being unjustifiably narrow and unlikely to contain the true age. We believe these results indicate that most forensic insect development studies should involve the measurement of entire age cohorts rather than subsamples of one or more cohorts.

Evaluating the utility of hexapod species for calculating a confidence interval about a succession based postmortem interval estimate

Carrion insect succession patterns have long been used to estimate the postmortem interval (PMI) during a death investigation. However, no published carrion succession study included sufficient replication to calculate a confidence interval about a PMI estimate based on occurrence data. We exposed 53 pig carcasses (16±2.5 kg), near the likely minimum needed for such statistical analysis, at a site in north-central Indiana, USA, over three consecutive summer seasons. Insects and Collembola were sampled daily from each carcass for a total of 14 days, by this time each was skeletonized. The criteria for judging a life stage of a given species to be potentially useful for succession-based PMI estimation were (1) nonreoccurrence (observed during a single period of presence on a corpse), and (2) found in a sufficiently large proportion of carcasses to support a PMI confidence interval. For this data set that proportion threshold is 45/53. Of the 266 species collected and identified, none was nonreoccuring in that each showed at least a gap of one day on a single carcass. If the definition of nonreoccurrence is relaxed to include such a single one-day gap the larval forms of Necrophilaamericana, Fanniascalaris, Cochliomyia macellaria, Phormiaregina, and Luciliaillustris satisfied these two criteria. Adults of Creophilus maxillosus, Necrobiaruficollis, and Necrodessurinamensis were common and showed only a few, single-day gaps in occurrence. C.maxillosus, P.regina, and L.illustris displayed exceptional forensic utility in that they were observed on every carcass. Although these observations were made at a single site during one season of the year, the species we found to be useful have large geographic ranges. We suggest that future carrion insect succession research focus only on a limited set of species with high potential forensic utility so as to reduce sample effort per carcass and thereby enable increased experimental replication.

First report of Blaesoxipha plinthopyga (Diptera: Sarcophagidae) from a human corpse in the U.S.A. and a new state geographic record based on specimen genotype

Carrion flies in the taxonomic family Sarcophagidae are often recovered from a human corpse. However, because such specimens are difficult to identify, the forensic literature on this taxon is quite limited compared with that of the commonly employed Calliphoridae. Faced with a sarcophagid larva that could not be identified microscopically from a death investigation in the state of Idaho, we generated cytochrome oxidase one DNA sequence data from the specimen. Comparison to a reference data set of forensically significant sarcophagids from Canada and the U.S.A. confirmed that this was the first discovery of Blaesoxipha plinthopyga in a human corpse in the U.S.A. and the first record of this species in Idaho. Because B. plinthopyga occurs from the Northern U.S.A. to the Neotropics, it is potentially useful for estimating time since death at many locations.

Estimating postmortem interval using RNA degradation and morphological changes in tooth pulp

The accurate determination of time since death, or postmortem interval (PMI), can be critical in the investigation of suspicious deaths. Knowing when a suspicious death occurred can limit the number of potential suspects to those without a viable alibi for the time of the crime. The forensic techniques currently employed to determine PMI: pathology, entomology, and anthropology, are accurate over different time periods following death. A large gap in time exists between the capabilities of forensic entomology and traditional anthropology, leaving a period in which PMI is difficult to estimate. In this study, time-dependent differences in RNA decay rates were examined to extend the time frame over which early PMI estimates can be made. Comparing the decay rates of a large, labile segment of β-actin RNA and a smaller, more stable, non-overlapping segment of the same RNA from tooth pulp, we were able to estimate PMI values of pigs buried within a shallow grave for up to 84 days. This compares favorably to an estimate of PMI using insect data. Full skeletonization and loss of insect activity was observed by day 28 of our study. In addition to differences in RNA decay rates, morphological changes were observed in the pulp as it aged postmortem. To provide a quantitative measure of progressive color changes, analysis of digital photographs of each tooth's pulp were used to construct a simple colorimetric assay. This assay was then used to cluster ages of pulp samples by color. The two assays, used in combination with one another, can create a more precise estimate of PMI. The potential advantages of this molecular means of estimating PMI include extending the time frame for such estimates, is applicable to samples collected worldwide (no specialized knowledge of local insect fauna is required), is relatively fast, and inexpensive.

Molecular systematics of the Calliphoridae (Diptera: Oestroidea): evidence from one mitochondrial and three nuclear genes

Approximately 8% of calyptrate species diversity comes from the Calliphoridae, which includes flies of medical, veterinary, and forensic importance. The status of family Calliphoridae has for years been the central systematic problem of the superfamily Oestroidea, and phylogenetic relationships between the key groups of the Calliphoridae are unresolved and controversial. We reconstructed phylogenies of the Calliphoridae within the larger context of the other Oestroidea based on 5,189 bp of combined data from one mitochondrial (cytochrome oxidase subunit one) and three nuclear (carbamoylphosphate synthetase, elongation factor one alpha, and 28S ribosomal RNA) genes using maximum parsimony, maximum likelihood, and Bayesian methods. Trees obtained from the different phylogenetic methods were almost identical. Calliphoridae is polyphyletic, with the phylogenetic position of Mesembrinellinae still uncertain but clearly outside the lineage that includes other Calliphoridae and some noncalliphorids, and Polleniinae is the sister group of the family Tachinidae. Strong support for a sister group relationship between Rhiniinae and traditional calliphorid subfamilies conflicts with a recent proposal to give Rhiniinae family status. All calliphorid subfamilies (except Calliphorinae) for which we had more than one species were monophyletic. Melanomyinae was nested within Calliphorinae. Toxotarsinae was more closely related to Calliphorinae rather than, as indicated by morphology, to Chrysomyinae. Efforts to resolve the relationships of the Oestroid families were largely inconclusive, although the monophyly of the superfamily was strongly supported.

Amplified fragment length polymorphism confirms reciprocal monophyly in Chrysomya putoria and Chrysomya chloropyga: a correction of reported shared mtDNA haplotypes

Reinvestigation of mitochondrial haplotypes previously reported to be shared between the Afrotropical blowflies Chrysomya putoria Weidemann and Chrysomya chloropyga Weidemann (Diptera: Calliphoridae) revealed an error resulting from the misidentification of specimens. Preliminary amplified fragment length polymorphism (AFLP) analysis of the original and additional individuals again failed to find reciprocal monophyly, leading to a re-examination of the specimens for diagnostic male genitalic characters that were first described following the earlier study. Four of the original study specimens were found to have been misidentified, and definitive analysis of both mtDNA and AFLP genotypes using phylogenetic analysis and genetic assignment showed that each species was indeed reciprocally monophyletic. In addition to correcting the earlier error, this study illustrates how AFLP analysis can be used for efficient and effective specimen identification through both phylogenetic analysis and genetic assignment, and suggests that the latter method has special advantages for identification when no conspecific specimens are represented in the reference database.

Molecular phylogeny of the blowfly genus Chrysomya

Chrysomya Robineau-Desvoidy (Diptera: Calliphoridae) is a genus of blowfly commonly observed in tropical and subtropical countries of the Old World. Species in this genus are vectors of bacteria, protozoans and helminths, cause myiasis, are predators of other carrion insects, and are important forensic indicators. Hypotheses concerning the evolution of sex determination, larval anatomy and genome size in Chrysomya have been difficult to evaluate because a robust phylogeny of the genus was lacking. Similarly, the monophyly of subgenera was uncertain. The phylogeny of Chrysomya spp. was reconstructed based on 2386 bp of combined mitochondrial cytochrome oxidase subunit I (COI) and nuclear carbamoylphosphate synthetase (CPS) genes. Maximum parsimony (MP), maximum likelihood (ML) and Bayesian analysis (BA) differed only slightly in the resulting tree topology. Chrysomya was monophyletic. Monogenic reproduction is almost certainly derived rather than, as has been suggested, primitive within the genus, and tuberculate larvae probably evolved twice. Genome size is more likely to have decreased over evolutionary time rather than, as has been suggested, increased within the genus, but its correlation with developmental time was not observed. The subgenera Microcalliphora, Eucompsomyia and Achoetandrus were recovered as monophyletic.

Survey of the genetic diversity of Phormia regina (Diptera: Calliphoridae) using amplified fragment length polymorphisms

There is very little information concerning carrion fly population genetic structure. We generated amplified fragment length polymorphism (AFLP) profiles for the common blowfly, Phormia regina (Meigen), from sites spanning the contiguous United States. Analysis of molecular variance (AMOVA) based on 232 loci found significant variation (phi(SC) = 23%) among discrete samples (those collected at a bait in one location over a short period of time). Samples collected in the same location but at different times were also distinct. When samples were pooled into geographic regions (east, central, west), the variation was negligible (phi(CT) = 0%). A Mantel test found only a very weak correlation between individual genetic and geographic distances. Relative relatedness coefficients based on shared allele proportions indicated individual samples were likely to contain close relatives. P. regina arriving at an individual carcass typically represent a nonrandom sample of the population despite a lack of geographic structure. A female blow fly produces hundreds of offspring at one time; therefore, newly emerged siblings may respond in concert to an odor plume. These results may be of interest to forensic entomologists, many of whom use a laboratory colony founded from a small sample for the growth studies that support casework. Discrepancies between published growth curves may reflect such random differences in the founding individuals.

Application of DNA-based methods in forensic entomology

A forensic entomological investigation can benefit from a variety of widely practiced molecular genotyping methods. The most commonly used is DNA-based specimen identification. Other applications include the identification of insect gut contents and the characterization of the population genetic structure of a forensically important insect species. The proper application of these procedures demands that the analyst be technically expert. However, one must also be aware of the extensive list of standards and expectations that many legal systems have developed for forensic DNA analysis. We summarize the DNA techniques that are currently used in, or have been proposed for, forensic entomology and review established genetic analyses from other scientific fields that address questions similar to those in forensic entomology. We describe how accepted standards for forensic DNA practice and method validation are likely to apply to insect evidence used in a death or other forensic entomological investigation.

Phylogenetic analysis of forensically important Lucilia flies based on cytochrome oxidase I sequence: a cautionary tale for forensic species determination

Forensic scientists are increasingly using DNA to identify the species of a tissue sample. However, little attention has been paid to basic experimental design issues such as replication and the selection of taxa when designing a species diagnostic test. We present an example using the forensically important fly genus Lucilia in which an increasingly larger sample size revealed that species diagnosis based on the commonly used cytochrome oxidase I gene (COI) was less straightforward than we initially thought. This locus may still be useful for diagnosing Lucilia specimens, but additional knowledge other than the genotype will be required to reduce the list of candidate species to include only forms that can be distinguished by COI. We believe that these results illustrate the importance of study design and biological knowledge of the study species when proposing a DNA-based identification test for any taxonomic group.

Validation of a DNA-based method for identifying Chrysomyinae (Diptera: Calliphoridae) used in a death investigation

Many authors have proposed DNA-based methods for identifying an insect specimen associated with human remains. However, almost no attempt has been made to validate these methods using additional observations. We tested a protocol for identifying insects in the blow fly subfamily Chrysomyinae (Diptera: Calliphoridae) often found to be associated with a human corpse in Canada or the USA. This method uses phylogenetic analysis of DNA sequence from a short segment of the mitochondrial gene for cytochrome oxidase one (COI). Test chrysomyine COI sequences were obtained from 245 newly sequenced specimens and 51 specimens from the published literature. Published sequences from representatives of nonchrysomyine genera were also included to check for the possibility of a false positive identification. All of the chrysomyine test haplotypes were correctly identified with strong statistical support, and there were no false positives. This method appears to be an accurate and robust technique for identifying chrysomyine species from a death investigation in this geographic region. The far northern species Protophormia atriceps was not evaluated; therefore, caution is required in applying this method at very high latitudes in North America.

Forensic genetic analysis of insect gut contents

Entomological evidence is most often used for estimating the postmortem interval, but fly larvae can also be a source of vertebrate DNA. Forensic analysis of DNA recovered from a larva's gut can be used to identify what the larva had been feeding on. During our previous research studies, we used the same DNA extraction for the dual purpose of identifying the insect species and associating a maggot with its last meal. In our experience, we have encountered several situations where this method for associating a maggot with a corpse would have been useful, such as removal of remains from a suspected crime scene, an alternative food source is nearby the scene or the body, and a chain-of-evidence dispute. However, since maggot gut content analysis is a quite brand-new area of study, many of the limitations of the technique have not yet been explored. The results of our most recent research studies suggest that third-instar larvae actively feeding on the corpse can be considered the best source of human DNA, better than postfeeding or starved larvae. In this paper, the state of the art of forensic genetic analysis of maggot gut contents is reviewed.

Recent African derivation of Chrysomya putoria from C. chloropyga and mitochondrial DNA paraphyly of cytochrome oxidase subunit one in blowflies of forensic importance

Chrysomya chloropyga (Wiedemann) and C. putoria (Wiedemann) (Diptera: Calliphoridae) are closely related Afrotropical blowflies that breed in carrion and latrines, reaching high density in association with humans and spreading to other continents. In some cases of human death, Chyrsomya specimens provide forensic clues. Because the immature stages of such flies are often difficult to identify taxonomically, it is useful to develop DNA-based tests for specimen identification. Therefore we attempted to distinguish between C. chloropyga and C. putoria using mitochondrial DNA (mtDNA) sequence data from a 593-bp region of the gene for cytochrome oxidase subunit one (COI). Twelve specimens from each species yielded a total of five haplotypes, none being unique to C. putoria. Therefore it was not possible to distinguish between the two species using this locus. Maximum parsimony analysis indicated paraphyletic C. chloropyga mtDNA with C. putoria nested therein. Based on these and previously published data, we infer that C. putoria diverged very recently from C. chloropyga.

Influence of an injury reduction program on injury and fitness outcomes among soldiers

OBJECTIVE

This study evaluated the influence of a multiple injury control intervention on injury and physical fitness outcomes among soldiers attending United States Army Ordnance School Advanced Individual Training.

METHODS

The study design was quasiexperimental involving a historical control group (n = 2559) that was compared to a multiple intervention group (n = 1283). Interventions in the multiple intervention group included modified physical training, injury education, and a unit based injury surveillance system (UBISS). The management responsible for training independently formed an Injury Control Advisory Committee that examined surveillance reports from the UBISS and recommended changes to training. On arrival at school, individual soldiers completed a demographics and lifestyle questionnaire and took an army physical fitness test (APFT: push-ups, sit-ups, and two mile run). Injuries among soldiers were tracked by a clinic based injury surveillance system that was separate from the UBISS. Soldiers completed a final APFT eight weeks after arrival at school.

RESULTS

Cox regression (survival analysis) was used to examine differences in time to the first injury while controlling for group differences in demographics, lifestyle characteristics, and physical fitness. The adjusted relative risk of a time loss injury was 1.5 (95% confidence interval 1.2 to 1.8) times higher in the historical control men and 1.8 (95% confidence interval 1.1 to 2.8) times higher in the historical control women compared with the multiple intervention men and women, respectively. After correcting for the lower initial fitness of the multiple intervention group, there were no significant differences between the multiple intervention and historical control groups in terms of improvements in push-ups, sit-ups, or two mile run performance.

CONCLUSIONS

This multiple intervention program contributed to a reduction in injuries while improvements in physical fitness were similar to a traditional physical training program previously used at the school.

Mitochondrial DNA and STR analyses of maggot crop contents: effect of specimen preservation technique

DNA analysis of maggot crop contents can be used to identify a missing body or aid entomologists with interpreting evidence used for PMI estimations. Entomological evidence is often collected and preserved to keep identifiable external features intact. The preservation methods currently in use may not be suitable for preserving DNA in the maggot crop for later analysis. In this study, carrion maggots raised on human tissue were preserved under the following 8 preservation conditions: no fluid at -70 degrees C, no fluid at 4 degrees C, no fluid at 24 degrees C, 70% ethanol at 4 degrees C, 70% ethanol at 24 degrees C, 95% ethanol at 24 degrees C, Kahle's solution at 24 degrees C and formaldehyde at 24 degrees C. Maggots were dissected following 2 weeks, 8 weeks and 6 months of preservation. The maggot crops were extracted, human DNA was quantitated, and an attempt was made at amplifying mitochondrial DNA (mtDNA) and short tandem repeat (STR) loci. Both mtDNA and STRs were successfully amplified from maggots stored in ethanol or without any preservation fluid. Formalin-containing preservation solutions reduced the recovery of DNA. The best results were observed from maggots stored without any preservation fluid at -70 degrees C.

Surface sterilization of a maggot using bleach does not interfere with mitochondrial DNA analysis of crop contents

Mitochondrial DNA analysis of a maggot crop can identify the corpse a maggot has been feeding on. Analysis of the crop could be useful in a criminal investigation if maggots are found at a suspected crime scene in the absence of a body, or if there is a question of whether a maggot used in postmortem interval estimations moved onto the corpse from another food source. Such analysis can also resolve a chain of custody dispute if it has been suggested that larval samples have been switched. When recovering DNA from a maggot crop, the analyst must be careful to avoid external contamination. We investigated the effects of three simple wash methods developed to reduce external contamination. Maggots raised on pig liver and intentionally contaminated with cow blood were washed using water, 20% bleach, or a solution containing the enzyme DNase. Only washing the maggots in 20% bleach reduced the amount of vertebrate DNA amplified from the maggots' exteriors. No wash method affected the ability to recover DNA from the maggot crops.

Paraphyly in Hawaiian hybrid blowfly populations and the evolutionary history of anthropophilic species

Complementary nuclear (28S rRNA) and mitochondrial (COI + II) gene markers were sequenced from the blowflies, Lucilia cuprina and Lucilia sericata, from Europe, Africa, North America, Australasia and Hawaii. Populations of the two species were phylogenetically distinct at both genes, with one exception. Hawaiian L. cuprina possessed typical L. cuprina-type rRNA, but had L. sericata-type mitochondrial (COI + II) sequences. An explanation for this pattern is that Hawaiian flies are hybrids and comparison of observed levels of sequence divergence to possible introduction events, e.g. Polynesian colonization, suggests that Hawaiian L. cuprina may be evolving rapidly. Moreover, the monophyly of these flies also suggests that the L. sericata mtDNA haplotype was apparently fixed in Hawaiian L. cuprina by lineage sorting, indicating a population bottleneck in the evolutionary history of these island flies.

DNA-based identification and molecular systematics of forensically important Sarcophagidae (Diptera)

Sarcophagid flies have many characteristics that make them ideal forensic indicators. However, their utility is severely limited because it is difficult or impossible to determine the species of a sarcophagid larva, and in many instances an adult specimen, based on anatomy. We developed a database of mitochondrial DNA sequence data that makes it possible to identify all sarcophagid species likely to be found feeding on a human corpse at an urban location in Canada or the USA. Analyses were based on a 783 base pair region of the gene for cytochrome oxidase subunit one (COI). The species analyzed, including some of no forensic importance that were included for purposes of phylogenetic comparisons, were members of the genera Sarcophaga, Peckia, Blaesoxipha, Rovinia, Wohlfahrtia, Brachicoma (all Sarcophagidae), and Musca (Muscidae).

DNA-based identification of forensically important Chrysomyinae (Diptera: Calliphoridae)

Identifying an insect specimen is an important first step in a forensic-entomological analysis. However, diagnostic morphological criteria are lacking for many species and life stages. We demonstrate a method for using mitochondrial DNA sequence data and phylogenetic analysis to identify any specimen of the blow fly subfamily Chrysomyinae likely to be collected from a human corpse within Canada or the USA. The reliability of the method was illustrated by analyzing specimens designed to mimic the information likely to be obtained from highly degraded specimens as well as specimens collected from widely separated geographic locations. Our sequence database may be suitable for another country provided the investigator knows the local fly fauna well enough to narrow the choice of chrysomyine species to those used in this study.

Porous calcium polyphosphate scaffolds for bone substitute applications -- in vitro characterization

Porous structures were formed by gravity sintering calcium polyphosphate (CPP) particles of either 106-150 or 150-250 microm size to form samples with 30-45 vol% porosity with pore sizes in the range of 100 microm (40-140 microm). Tensile strength of the samples assessed by diametral compression testing indicated relatively high values for porous ceramics with a maximum strength of 24.1 MPa for samples made using the finer particles (106-150 microm). X-ray diffraction studies of the sintered samples indicated the formation of beta-CPP from the starting amorphous powders. In vitro aging in 0.1 M tris-buffered solution (pH 7.4) or 0.05 M potassium hydrogen phthalate buffered solution (pH 4.0) at 37 degreesC for periods up to 30d indicated an initial rapid loss of strength and P elution by 1 d followed by a more gradual continuing strength and P loss resulting in strengths at 30d equal to about one-third the initial value. The observed structures, strengths and in vitro degradation characteristics of the porous CPP samples suggested their potential usefulness as bone substitute materials pending subsequent in vivo behaviour assessment.

Human and insect mitochondrial DNA analysis from maggots

During the course of our forensic investigations, we have encountered situations where it would have been useful to have evidence, other than direct contact between the two, for concluding that a carrion-fly maggot developed on a particular human victim. If a maggot collected during a death investigation did not develop on the victim, then its age is not relevant to estimating the postmortem interval. In this study we demonstrate that mitochondrial DNA (mtDNA) sequence data can be obtained from the dissected gut of a maggot that had fed on human tissue. These data can be used to identify both the human corpse upon which the maggot had been feeding and the species of the maggot itself.

A Comparative Study of the Adsorption of Transition Metals on Kaolinite

Adsorption of Pb(II), Cu(II), Zn(II), Co(II), and Mn(II) to kaolinite was measured at 25 degrees C in the presence of 5 mM KNO(3). Adsorption edges (pH 3-10; total metal concentration 100 µM) for Pb(II) and Cu(II) were sigmoid, but those for Zn(II) and Co(II), and especially Mn(II), were characterized by distinct steps after about 40% adsorption. Adsorption isotherms (concentrations up to 60 µM; fixed pH) at pH 5.50 followed the simple Langmuir equation, but those at pH 7.50 (Zn(II), Co(II), and Mn(II)) required a two-site model. More protons were released during adsorption at the higher pH. All adsorption data, and the results of potentiometric titrations of kaolinite suspensions (alone and in the presence of metals at 100 µM), can be fitted closely by a constant-capacitance surface complexation model that incorporates two bidentate surface complexes. One involves electrostatic attraction between transition metal ions and the permanent, negatively charged sites on the silanol faces of kaolinite. The other is an inner-sphere complex at the variable-charge surface hydroxyl groups situated at the crystal edges and on the aluminol faces. Copyright 1999 Academic Press.

Key to third-instar chrysomyinae (Diptera: Calliphoridae) from carrion in the continental United States

The introduction of 4 Chrysomya Robineau-Desvoidy spp. to the Americas has made obsolete previously published keys to Nearctic calliphorid larvae, particularly those covering the subfamily Chrysomyinae. To assist forensic entomologists, ecologists, and public health workers, we provide a key to 3rd instars of 8 chrysomyine species reported from or likely to occur in carrion within the continental United States. The rare (in the United States) species Cochliomyia aldrichi Del Ponte, C. minima Shannon, and Chloroprocta idioidea (Robineau-Desvoidy) are not included because specimens and suitable descriptions were unavailable.

Molecular phylogeny of Chrysomya albiceps and C. rufifacies (Diptera: Calliphoridae)

Mitochondrial DNA was used to infer the phylogeny and genetic divergences of Chrysomya albiceps (Wiedemann) and C. rufifacies (Maquart) specimens from widely separated localities in the Old and New World. Analyses based on a 2.3-kb region including the genes for cytochrome oxidase subunits I and II indicated that the 2 species were separate monophyletic lineages that have been separated for > 1 million years. Analysis of DNA, in the form of either sequence or restriction fragment-length polymorphism (RFLP) data, will permit the identification of problematic specimens.

The Influence of Temperature on the Adsorption of Cadmium(II) and Cobalt(II) on Goethite

The adsorption of Cd(II) and Co(II) onto goethite was measured at five temperatures between 10 and 70 degrees C. For both cations the amount adsorbed at any given pH increased as the temperature was increased. Cd(II) adsorbed at a slightly lower pH at each temperature than Co(II). Adsorption isotherms at pH 7.00 for Cd(II) could be fitted closely by a simple Langmuir model, but a two-site Langmuir model was needed for Co(II). Potentiometric titrations of goethite suspensions in the presence and absence of added cation could be modeled closely by a constant-capacitance surface complexation model that assumed the adsorption reactions M2+ + SOH &lrhar; SOM+ + H+ and M2+ + SOH + H2O &lrhar; SOMOH + 2H+, where M represents Cd or Co. This model also fitted the experimental data from the adsorption edge and adsorption isotherm experiments. Thermodynamic parameters estimated from both Langmuir and surface complexation models showed that the adsorption of both metals was endothermic. Values obtained for the adsorption enthalpies from both modeling schemes were similar for both cations. Estimates of the adsorption entropies were model-dependent: Langmuir parameters yielded positive entropies, while some of the surface complexation parameters generated negative adsorption entropies. Copyright 1999 Academic Press.

The Influence of Temperature on the Adsorption of Cadmium(II) and Cobalt(II) on Kaolinite

The adsorption of Cd(II) and Co(II) onto kaolinite was investigated at five temperatures between 10 and 70 degreesC. Adsorption edges showed that both Cd(II) and Co(II) adsorbed onto kaolinite in two stages, separated by a plateau between pH 4 and 7. Initial adsorption commenced at about the same pH for both cations, but at each temperature the second-stage adsorption occurred at a slightly lower pH for Co(II) than for Cd(II). At higher temperatures adsorption was generally shifted to lower pH. Adsorption isotherms at pH 5.50 for both cations could be fitted closely by a simple Langmuir model at all temperatures. A two-site Langmuir model provided a substantially better fit for isotherms at pH 7.50 for Cd(II) and pH 7.00 for Co(II). At pH 5.50 the maximum adsorption density estimated from Langmuir modelling was approximately the same (1 µmol m-2) for both cations and at all temperatures. A similar value was found for one of the model sites at pH 7.50 for Cd(II) and at pH 7.00 for Co(II). Potentiometric titrations of kaolinite suspensions, in the presence and absence of added Cd(II) or Co(II), could be modeled accurately by a constant-capacitance surface complexation model. The data for adsorption of both cations could be fitted at all temperatures using a model that assumed ion exchange at permanent charge sites on silanol faces and complexation to hydroxyl edge groups. Thermodynamic parameters estimated from both the Langmuir and surface complexation models showed that adsorption of Cd(II) and Co(II) were endothermic. For the surface complexation model, enthalpies of adsorption on exchange sites were about 10 kJ mol-1, but at the variable-charge sites the enthalpy changes were about 70 kJ mol-1. For all these reactions the entropy changes were positive, with values of the order of 100 J K-1 mol-1. Trends for the Langmuir model were qualitatively similar. Copyright 1998 Academic Press.

Human neutrophils express the prostaglandin G/H synthase 2 gene when stimulated with bacterial lipopolysaccharide

Human blood neutrophils (PMN) rapidly release arachidonic acid (AA) from cellular phospholipids when stimulated in vitro with a variety of inflammatory agonists. Free AA is then metabolized via 5'-lipoxygenase to produce bioactive mediators such as leukotriene B4 and 5-hydroxyeicosatetraenoate. Arachidonic acid can also be metabolized via the cyclooxygenase or prostaglandin G/H synthase (PGHS) pathway to form prostaglandins and thromboxane. We show here that human blood PMN express the PGHS 2 gene when stimulated with bacterial lipopolysaccharide (LPS). PGHS 2 mRNA increases within 30 min after LPS stimulation and PGHS 2 immunoreactive protein is detectable by 5 h. Although PGHS 1 mRNA is detectable in PMN, no immunoreactive protein is observed in either resting or LPS-stimulated cells. Following stimulation with LPS and expression of PGHS 2, PMN increase secretion of prostaglandin E2. This phenotypic change in PMN could be an important mechanism for regulating inflammation.