Hidden Decomposers: the Role of Bacteria and Fungi in Recently Intermittent Alpine Streams Heterotrophic Pathways.

The frequency of flow intermittency and drying events in Alpine rivers is expected to increase due to climate change. These events can have significant consequences for stream ecological communities, though the effects of reduced flow conditions on microbial communities of decomposing allochthonous leaf material require additional research. In this study, we investigated the bacterial and fungal communities associated with the decomposition of two common species of leaf litter, chestnut (Castanea sativa), and oak (Quercus robur). A sampling of experimentally placed leaf bags occurred over six collection dates (up to 126 days after placement) at seven stream sites in the Western Italian Alps with historically different flow conditions. Leaf-associated bacterial and fungal communities were identified using amplicon-based, high-throughput sequencing. Chestnut and oak leaf material harbored distinct bacterial and fungal communities, with a number of taxonomic groups differing in abundance, though bacterial community structure converged later in decomposition. Historical flow conditions (intermittent vs perennial rivers) and observed conditions (normal flow, low flow, ongoing drying event) had weaker effects on bacterial and fungal communities compared to leaf type and collection date (i.e., length of decomposition). Our findings highlight the importance of leaf characteristics (e.g., C:N ratios, recalcitrance) to the in-stream conditioning of leaf litter and a need for additional investigations of drying events in Alpine streams. This study provides new information on the microbial role in leaf litter decomposition with expected flow changes associated with a global change scenario.

Mycobacterium ulcerans toxin, mycolactone may enhance host-seeking and oviposition behaviour by Aedes aegypti (L.) (Diptera: Culicidae).

The ecological functions of many toxins continue to remain unknown for those produced by environmental pathogens. Mycobacterium ulcerans, the causative agent of the neglected tropical disease, Buruli ulcer, produces a cytotoxic macrolide, mycolactone, whose function(s) in the environment remains elusive. Through a series of dual-choice behaviour assays, they show that mycolactone may be an interkingdom cue for the yellow fever mosquito, Aedes aegypti, seeking blood-meals as well as oviposition sites. Results provide novel insight into the evolution between bacteria and potential vectors. While further studies are needed to determine if mycolactone is an actual signal rather than simply a cue, this discovery could serve as a model for determining roles for toxins produced by other environmental pathogens and provide opportunities for developing novel strategies for disease prevention. The relationship between M. ulcerans, mycolactone, and Ae. aegypti further suggests there could be an amplification effect for the spread of pathogens responsible for other diseases, such as yellow fever and dengue.

Fluorescently labeled bacteria provide insight on post-mortem microbial transmigration.

Microbially mediated mechanisms of human decomposition begin immediately after death, and are a driving force for the conversion of a once living organism to a resource of energy and nutrients. Little is known about post-mortem microbiology in cadavers, particularly the community structure of microflora residing within the cadaver and the dynamics of these communities during decomposition. Recent work suggests these bacterial communities undergo taxa turnover and shifts in community composition throughout the post-mortem interval. In this paper we describe how the microbiome of a living host changes and transmigrates within the body after death thus linking the microbiome of a living individual to post-mortem microbiome changes. These differences in the human post-mortem from the ante-mortem microbiome have demonstrated promise as evidence in death investigations. We investigated the post-mortem structure and function dynamics of Staphylococcus aureus and Clostridium perfringens after intranasal inoculation in the animal model Mus musculus L. (mouse) to identify how transmigration of bacterial species can potentially aid in post-mortem interval estimations. S. aureus was tracked using in vivo and in vitro imaging to determine colonization routes associated with different physiological events of host decomposition, while C. perfringens was tracked using culture-based techniques. Samples were collected at discrete time intervals associated with various physiological events and host decomposition beginning at 1h and ending at 60 days post-mortem. Results suggest that S. aureus reaches its highest concentration at 5-7 days post-mortem then begins to rapidly decrease and is undetectable by culture on day 30. The ability to track these organisms as they move in to once considered sterile space may be useful for sampling during autopsy to aid in determining post-mortem interval range estimations, cause of death, and origins associated with the geographic location of human remains during death investigations.

Seasonal necrophagous insect community assembly during vertebrate carrion decomposition.

Necrophagous invertebrates have been documented to be a predominant driver of vertebrate carrion decomposition; however, very little is understood about the assembly of these communities both within and among seasons. The objective of this study was to evaluate the seasonal differences in insect taxa composition, richness, and diversity on carrion over decomposition with the intention that such data will be useful for refining error estimates in forensic entomology. Sus scrofa (L.) carcasses (n = 3-6, depending on season) were placed in a forested habitat near Xenia, OH, during spring, summer, autumn, and winter. Taxon richness varied substantially among seasons but was generally lower (1-2 taxa) during early decomposition and increased (3-8 taxa) through intermediate stages of decomposition. Autumn and winter showed the highest richness during late decomposition. Overall, taxon richness was higher during active decay for all seasons. While invertebrate community composition was generally consistent among seasons, the relative abundance of five taxa significantly differed across seasons, demonstrating different source communities for colonization depending on the time of year. There were significantly distinct necrophagous insect communities for each stage of decomposition, and between summer and autumn and summer and winter, but the communities were similar between autumn and winter. Calliphoridae represented significant indicator taxa for summer and autumn but replaced by Coleoptera during winter. Here we demonstrated substantial variability in necrophagous communities and assembly on carrion over decomposition and among seasons. Recognizing this variation has important consequences for forensic entomology and future efforts to provide error rates for estimates of the postmortem interval using arthropod succession data as evidence during criminal investigations.

A roadmap for bridging basic and applied research in forensic entomology.

The National Research Council issued a report in 2009 that heavily criticized the forensic sciences. The report made several recommendations that if addressed would allow the forensic sciences to develop a stronger scientific foundation. We suggest a roadmap for decomposition ecology and forensic entomology hinging on a framework built on basic research concepts in ecology, evolution, and genetics. Unifying both basic and applied research fields under a common umbrella of terminology and structure would facilitate communication in the field and the production of scientific results. It would also help to identify novel research areas leading to a better understanding of principal underpinnings governing ecosystem structure, function, and evolution while increasing the accuracy of and ability to interpret entomological evidence collected from crime scenes. By following the proposed roadmap, a bridge can be built between basic and applied decomposition ecology research, culminating in science that could withstand the rigors of emerging legal and cultural expectations.

When entomological evidence crawls away: Phormia regina en masse larval dispersal.

In criminal and civil legal investigations the forensic entomologist usually assists in providing an estimate of the postmortem interval, which closely couples with the time or period of insect activity. A minimum period of insect activity is often interpreted and estimated by dipteran larval developmental age of the oldest specimens collected at a crime scene and/or autopsy. In entomological evidence protocols investigators are recommended to search a 2-10 m perimeter area for the oldest larvae that may have begun to disperse away from the body for burial and pupation. In this study, we described a case of a large aggregate (> 90% larvae) en masse postfeeding dispersal of blow fly larvae away from replicate swine carcasses serving as models of human decomposition. Larval dispersal was evaluated for a spring and a summer trial, with en masse characteristics only occurring during the latter. This en masse dispersal occurred in five out of six replicate carcasses and masses moved from 2 to 26 m away. These data and observations suggest the importance of performing searches > 10 m from human remains for entomological evidence at crime scenes. By missing the oldest larvae at a crime scene, interpretation of entomological evidence can be compromised and erroneous. Based on these data and observations we recommend the crime scene investigators and researchers consider increasing the search radius around crime scene remains to increase the likelihood that the oldest larvae have been collected for analysis.

Role of larval sexual dimorphism, biased sex ratios, and habitat on the energetics of a tropical chironomid.

Larval sex dimorphism, fecundity, and sex ratios have been rarely studied in lotic insects, but can have ecological, energetic, and evolutionary importance. I evaluated the effect of microhabitat quality on larval and pupal sex dimorphism and sex ratios using a Hawaiian chironomid (Telmatogeton torrenticola Terry) and examined differences between sex-corrected and noncorrected biomass and secondary production estimates. Larvae and pupae were collected from two microhabitat types defined by microscale flow hydraulics to test for habitat effects on sex dimorphism, sex ratios, fecundity, standing stock biomass, secondary production, and Production/Biomass (P/B) ratios. Female larvae were more than twice as large as males, and this was more pronounced in pupae. Males were twice as abundant as females, and there was no effect of habitat on fourth-instar density. There was, however, a significant habitat effect on morphology, larval body size, standing stock biomass, secondary production, and P/B ratios. Biomass was not statistically different between sexes, but sex-corrected biomass was significantly lower than noncorrected biomass in both habitats but is likely not biologically significant. Sex-corrected secondary production estimates were 69-85% of noncorrected estimates depending on habitat, and sex correction did have a significant effect on P/B ratios in microhabitats of lower quality. This study is one of the first to address sex dimorphism and sex ratios in estimates of standing stock biomass and secondary production, providing initial evidence that microhabitat quality is important to understanding chironomid population biology and the potential role of sex-related demographics in estimates of productivity.

Care of a patient with an infected ulcer of the foot.

The treatment of a patient whose case was complicated by diabetes mellitus is examined.

Reviews.

ACUTE AND CHRONIC WOUNDS NURSING MANAGEMENT A COLOUR GUIDE TO THE ASSESSMENT AND MANAGEMENT OF LEG ULCERS.

Managing a patient's infected wound site after a radical vulvectomy.

A study of the treatment of a patient who had undergone extensive surgery for carcinoma of the vulva.