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Quantico Station, VA, United States

Engel A.S.,Louisiana State University | Meisinger D.B.,TU Munich | Porter M.L.,University of Maryland Baltimore County | Payn R.A.,Montana State University | And 4 more authors.
ISME Journal | Year: 2010

Microbial mats in sulfidic cave streams offer unique opportunities to study redox-based biogeochemical nutrient cycles. Previous work from Lower Kane Cave, Wyoming, USA, focused on the aerobic portion of microbial mats, dominated by putative chemolithoautotrophic, sulfur-oxidizing groups within the Epsilonproteobacteria and Gammaproteobacteria. To evaluate nutrient cycling and turnover within the whole mat system, a multidisciplinary strategy was used to characterize the anaerobic portion of the mats, including application of the full-cycle rRNA approach, the most probable number method, and geochemical and isotopic analyses. Seventeen major taxonomic bacterial groups and one archaeal group were retrieved from the anaerobic portions of the mats, dominated by Deltaproteobacteria and uncultured members of the Chloroflexi phylum. A nutrient spiraling model was applied to evaluate upstream to downstream changes in microbial diversity based on carbon and sulfur nutrient concentrations. Variability in dissolved sulfide concentrations was attributed to changes in the abundance of sulfide-oxidizing microbial groups and shifts in the occurrence and abundance of sulfate-reducing microbes. Gradients in carbon and sulfur isotopic composition indicated that released and recycled byproduct compounds from upstream microbial activities were incorporated by downstream communities. On the basis of the type of available chemical energy, the variability of nutrient species in a spiraling model may explain observed differences in microbial taxonomic affiliations and metabolic functions, thereby spatially linking microbial diversity to nutrient spiraling in the cave stream ecosystem. © 2010 International Society for Microbial Ecology All rights reserved.

Stein M.L.,John Jay College of Criminal Justice | Schlesinger L.B.,John Jay College of Criminal Justice | Pinizzotto A.J.,FBI Academy
Journal of Forensic Sciences | Year: 2010

A closed case-file review of 211 sexual homicides identified 16 cases of necrophilia. The results of this unique descriptive study of necrophilia associated with sexual homicide provide information on crime-scene locations, methods of killing, body disposition, premortem sexual assault, specifics of the necrophilic acts, methods of victim abduction, and motivational dynamics. The findings suggest that the most common explanation for necrophilia - the offender's desire to have an unresisting partner - may not always be applicable in cases where this rare paraphilia is connected to sexual murder. The possibility of using crime-scene behaviors in these cases to investigate serial sexual murders is offered. © 2010 American Academy of Forensic Sciences.

Swan B.K.,University of California at Santa Barbara | Swan B.K.,Bigelow Laboratory for Ocean Sciences | Ehrhardt C.J.,FBI Academy | Reifel K.M.,University of Southern California | And 2 more authors.
Applied and Environmental Microbiology | Year: 2010

Sulfldic, anoxic sediments of the moderately hypersaline Salton Sea contain gradients in salinity and carbon that potentially structure the sedimentary microbial community. We investigated the abundance, community structure, and diversity of Bacteria and Archaea along these gradients to further distinguish the ecologies of these domains outside their established physiological range. Quantitative PCR was used to enumerate 16S rRNA gene abundances of Bacteria, Archaea, and Crenarchaeota. Community structure and diversity were evaluated by terminal restriction fragment length polymorphism (T-RFLP), quantitative analysis of gene (16S rRNA) frequencies of dominant microorganisms, and cloning and sequencing of 16S rRNA. Archaea were numerically dominant at all depths and exhibited a lesser response to environmental gradients than that of Bacteria. The relative abundance of Crenarchaeota was low (0.4 to 22%) at all depths but increased with decreased carbon content and increased salinity. Salinity structured the bacterial community but exerted no significant control on archaeal community structure, which was weakly correlated with total carbon. Partial sequencing of archaeal 16S rRNA genes retrieved from three sediment depths revealed diverse communities of Euryarchaeota and Crenarchaeota, many of which were affiliated with groups previously described from marine sediments. The abundance of these groups across all depths suggests that many putative marine archaeal groups can tolerate elevated salinity (5.0 to 11.8% [wt/vol]) and persist under the anaerobic conditions present in Salton Sea sediments. The differential response of archaeal and bacterial communities to salinity and carbon patterns is consistent with the hypothesis that adaptations to energy stress and availability distinguish the ecologies of these domains. Copyright © 2010, American Society for Microbiology. All Rights Reserved.

Harper K.A.,University of California at Davis | Harper K.A.,FBI Academy | Smart C.D.,Cornell University | Davis R.M.,University of California at Davis
Journal of Forensic Sciences | Year: 2011

A DNA-based macroarray was designed to quickly and accurately identify certain Amanita mushroom specimens at the species level. The macroarray included probes for Amanita phalloides and Amanita ocreata, toxic species responsible for most mushroom poisonings, and Amanita lanei and Amanita velosa, edible species sometimes confused with toxic species, based on sequences of the highly variable internal transcribed spacer (ITS) region of rDNA. A cryptic species related to A. ocreata and one related to A. lanei, identifiable by ITS sequences, were also included. Specific multiple oligonucleotide probes were spotted onto nylon membranes and the optimal hybridization temperatures were determined. The Amanita DNA array was highly specific, sensitive (0.5ng DNA/μL and higher were detected), and reproducible. In two case studies, the method proved useful when only small amounts of mushroom tissue remained after a suspected poisoning. An identification could be completed in 12h. © 2011 American Academy of Forensic Sciences.

Bachrach B.,Intelligent Automation Inc. | Jain A.,Intelligent Automation Inc. | Jung S.,Intelligent Automation Inc. | Koons R.D.,FBI Academy
Journal of Forensic Sciences | Year: 2010

Tool mark identification relies on the premise that microscopic imperfections on a tool's working surface are sufficiently unique and faithfully transferred to enable a one-to-one association between a tool and the tool marks it creates. This paper presents a study undertaken to assess the validity of this premise. As part of this study sets of striated tool marks were created under different conditions and on different media. The topography of these tool marks was acquired and the degree of similarity between them was quantified using well-defined metrics. An analysis of the resulting matching and nonmatching similarity distributions shows nearly error-free identification under most conditions. These results provide substantial support for the validity of the premise of tool mark identification. Because the approach taken in this study relies on a quantifiable similarity metric, the results have greater repeatability and objectivity than those obtained using less precise measures of similarity. © 2010 American Academy of Forensic Sciences.

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