Mouse Carcasses Research Articles

Selenomethionine promotes ANXA2 phosphorylation for proliferation and protein synthesis of myoblasts and skeletal muscle growth

Selenomethionine (Se-Met) has many beneficial effects on higher animals and human, and can regulate cellular physiology through distinct signaling pathways. However, the role and molecular mechanism of Se-Met in skeletal muscle growth remains unclear. In this study, we observed the effects of Se-Met on C2C12 myoblasts and skeletal muscle growth of mice, and explored the corresponding molecular mechanism. Se-Met affected proliferation and protein synthesis of C2C12 myoblasts in a hormesis type of relationship, and had an optimal stimulatory effect at 50 µM concentration. Se-Met also affected mTOR, ANXA2, and PKCα phosphorylation in the same manner. ANXA2 knockdown blocked the stimulation of Se-Met on cell proliferation and protein synthesis and inhibition of Se-Met on autophagy of C2C12 myoblasts. Western blotting analysis showed that PI3K inhibition blocked the stimulation of Se-Met on mTOR phosphorylation. ANXA2 knockdown further blocked the stimulation of Se-Met on PI3K and mTOR phosphorylation. Point mutation experiment showed that ANXA2 mediated the stimulation of Se-Met on the PI3K-mTOR signaling through phosphorylation at Ser26. PKCα interacted with ANXA2, and PKCα knockdown blocked the stimulation of Se-Met on ANXA2 phosphorylation at Ser26. Se-Met addition (7.5mg/kg diet, 4 weeks) increased mouse carcass weight, promoted gastrocnemius skeletal muscle growth and ANXA2 and mTOR phosphorylation in this tissue. Collectively, our findings reveal that Se-Met can promote proliferation and protein synthesis of myoblasts and skeletal muscle growth through ANXA2 phosphorylation.

Comparison and calibration of dose delivered by 137Cs and x-ray irradiators in mice

Objective. The Office of Radiological Security, U.S. Department of Energy's National Nuclear Security Administration, is implementing a radiological risk reduction program which seeks to minimize or eliminate the use of high activity radiological sources, including 137Cs, by replacing them with non-radioisotopic technologies, such as x-ray irradiators. The main goal of this paper is to evaluate the equivalence of the dose delivered by gamma- and x-ray irradiators in mice using experimental measurements and Monte Carlo simulations. We also propose a novel biophantom as an in situ dose calibration method. Approach. We irradiated mouse carcasses and 3D-printed mouse biophantoms in a 137Cs irradiator (Mark I-68) and an x-ray irradiator (X-Rad320) at three voltages (160 kVp, 225 kVp and 320 kVp) and measured the delivered radiation dose. A Geant4-based Monte Carlo model was developed and validated to provide a comprehensive picture of gamma- and x-ray irradiation in mice. Main Results. Our Monte Carlo model predicts a uniform dose delivered in soft-tissue for all the explored irradiation programs and in agreement with the absolute dose measurements. Our Monte Carlo model shows an energy-dependent difference between dose in bone and in soft tissue that decreases as photon energy increases. Dose rate depends on irradiator and photon energy. We observed a deviation of the measured dose from the target value of up to −9% for the Mark I-68, and up to 35% for the X-Rad320. The dose measured in the 3D-printed phantoms are equivalent to that in the carcasses within 6% uncertainty. Significance. Our results suggest that 320 kVp irradiation is a good candidate to substitute 137Cs irradiation barring a few caveats. There is a significant difference between measured and targeted doses for x-ray irradiation that suggests a strong need for in situ calibration, which can be achieved with 3D-printed mouse biophantoms. A dose correction is necessary for bone doses, which can be provided by a Monte Carlo calculation. Finally, the biological implications of the differences in dose rates and dose per photon for the different irradiation methods should be carefully assessed for each small-animal irradiation experiment.

Foraging risk in scavenging ecology: A study of scavenger behavior and patterns of bacterial growth

Scavenging constitutes an understudied energy pathway in terrestrial ecosystems, with important connections to disease ecology. A prevailing null hypothesis in scavenging ecology is that carcasses serve as a risk-free meal for whatever animal first encounters them on the landscape. We tested this hypothesis by focusing on a suspected risk that scavengers would face at carcasses: the risk of pathogen exposure. We conducted field trials with mouse carcasses in which we manipulated potential cues to pathogen risk and then monitored scavenger foraging decisions. Separately, we studied pathogen and commensal bacteria dynamics within mouse carcasses through time in the laboratory to better understand how carcass age might impact pathogen risk to scavengers. A visual cue to pathogen risk in the field (carcasses deployed in groups of 7 in 1 m2) caused facultative vertebrate scavengers to pass on the opportunity to feed at a rate six-times higher than for carcasses deployed singly (46.9% vs. 7.7%), suggesting an ability to perceive cues to pathogen risk at carcasses. The cues to carcass age, however, produced no effect on facultative scavenger behavior in our field trials. Laboratory trials demonstrated that both commensal enteric bacteria and a known pathogen (Listeria monocytogenes) increased at least through bloat and active decay stages in carcasses, suggesting that cues to carcass age may not help scavengers reduce pathogen risk early in decomposition. In providing evidence counter to the free meal hypothesis, our results support the continued formation of an alternative risk-based framework to understand scavenger behavior at carcasses.

Factors affecting searcher efficiency and scavenger removal of bat carcasses in Neotropical wind facilities

AbstractBat fatalities at wind facilities have been reported worldwide, and environmental impact assessments depend on searches for carcasses around wind turbines to quantify impacts. Some of the carcasses may go undetected by search teams or be removed by scavengers during search intervals, so these biases must be evaluated and taken into account in fatality estimation. We investigated the influence of different factors on searcher efficiency and scavenger removal in a dry forest area in northeastern Brazil, one of the regions with the highest density of wind turbines in the Neotropics. We conducted searcher efficiency and scavenger removal trials around 34 wind turbines from January 2017 to January 2018. Searcher efficiency was influenced by cover type, season, and carcass size, ranging between 12% for small bats in shrub vegetation during the rainy season and 96% for large bats in absent or sparse vegetation during the dry season. Carcass type and season affected scavenger removal; carcass persistence time was shorter for chicks (1.2 days) than for bats and mice (2.1 days), and the probability of a carcass persisting for a whole day was higher in the rainy season, while the probability of carcass persistence for 7, 14, and 28 days was higher in the dry season. The scavenger community was composed of canids, birds of prey, and insects, with systematic removal of carcasses by the crab‐eating fox (Cerdocyon thous) throughout the year and by dung beetles in the rainy season. Based on our findings, impact assessments of wind facilities on bats should conduct searcher efficiency trials in all seasons and cover types around wind turbines, using bat carcasses or models of different sizes. Scavenger removal trials should cover all seasons as well, and use mouse carcasses (but not chick carcasses) as surrogates for bats.

On the influence of environmental factors on the oviposition activity of necrophagous flies

Abstract1. Locating an optimal oviposition site can be a challenging task for female insects, especially when dealing with a patchy, unpredictable and ephemeral food source such as carrion. Understanding the biotic and abiotic parameters that influence the oviposition behaviour of necrophagous flies is not just of great biological importance but also essential for their application in legal investigations.2. In this study, we monitored the oviposition activity of necrophagous flies (Calliphoridae, Sarcophagidae) using mouse carcasses in an urban (city) and a rural (mixed forest) habitat in Frankfurt/Germany over a 2‐year period.3. Over 240 sampling days, 220,963 larvae of 4 blow fly species and 1 flesh fly were sampled. The most abundant species was the blow fly Lucilia ampullacea, followed by its family members Calliphora vicina and Lucilia caesar, the flesh fly Sarcophaga caerulescens and Lucilia sericata. Up to seven environmental parameters were statistically significant predictors for a colonisation of the carcasses, leading to unique patterns of seasonal and daily oviposition activity for all five species.4. Overall, the analysis showed that the seasonal adaption (the phenology of each species), the habitat (rural vs. urban) as well as temperature are the most important factors influencing the oviposition behaviour and activity of necrophagous blow flies and flesh flies.

Access to Resources Shapes Sex Differences Between Caring Parents

In species where both parents cooperate to care for their joint offspring, one sex often provides more care than the other. The magnitude of such sex differences often varies both between and within species and may depend on environmental conditions, such as access to resources, predation risk and interspecific competition. Here we investigated the impact of one such environmental variable – access to resources for breeding – on the magnitude of sex differences in parental care in the burying beetleNicrophorus vespilloides. This species breeds on the carcasses of small vertebrates, which are the sole food source for parents and offspring during breeding. We manipulated access to resources by providing pairs with mouse carcasses from a broad mass range (3.65–26.15 g). We then monitored subsequent effects on the duration and amount of care provided by males and females, male and female food consumption and weight change during breeding, and larval traits related to offspring performance. We found that males increased their duration of care as carcass mass increased, while females remained with the brood until it had completed its development irrespective of carcass mass. There were thus more pronounced sex differences in parental care when parents had access to fewer resources for breeding. Overall, our findings show that sex differences between caring parents vary depending on access to resources during breeding. The finding that males extended their duration of care on larger carcasses suggests that access to more resources leads to a shift toward more cooperation between caring parents.

Whole body potassium as a biomarker for potassium uptake using a mouse model

Potassium is known for its effect on modifiable chronic diseases like hypertension, cardiac disease, diabetes (type-2), and bone health. In this study, a new method, neutron generator based neutron activation analysis (NAA), was utilized to measure potassium (K) in mouse carcasses. A DD110 neutron generator based NAA assembly was used for irradiation.Thirty-two postmortem mice (n= 16 males and 16 females, average weight 22.02pm 1.3 and 17.9pm 1.1 g) were employed for this study. Soft-tissue equivalent mouse phantoms were prepared for the calibration. All mice were irradiated for 10 minutes, and the gamma spectrum with 42K was collected using a high efficiency, high purity germanium (HPGe) detector. A lead shielding assembly was designed and developed around the HPGe detector to obtain an improved detection limit. Each mouse sample was irradiated and measured twice to reduce uncertainty. The average potassium concentration was found to be significantly higher in males (2846 pm 525 upmu g/g) compared to females (2116.2 pm 432 upmu g/g). We also observed a significant correlation between potassium concentration and the weight of the mice. The detection limit for potassium quantification with the NAA system was 46 ppm. The radiation dose to the mouse was approximately 56 { pm 1.6 } mSv for 10-min irradiation. In conclusion, this method is suitable for estimating individual potassium concentration in small animals. The direct evaluation of total body potassium in small animals provides a new way to estimate potassium uptake in animal models. This method can be adapted later to quantify potassium in the human hand and small animals in vivo. When used in vivo, it is also expected to be a valuable tool for longitudinal assessment, kinetics, and health outcomes.

Behavioral dominance interactions between Nicrophorus orbicollis and N. tomentosus burying beetles (Coleoptera: Silphidae)

Asymmetric interference competition, where one species is behaviorally dominant over another, appears widespread in nature with the potential to structure ecological communities through trade-offs between competitive dominance and environmental tolerance. The details of how species interact and the factors that contribute to behavioral dominance, however, are poorly known for most species, yet such details are important for understanding when and why trade-offs occur. Here, we examine behavioral interactions between two species of burying beetles (Coleoptera: Silphidae) that compete for limited breeding resources (i.e., small vertebrate carcasses) in nature, to identify behaviors involved in interference competition and to test if large body size, species identity, or time of arrival best predict behavioral dominance among species. To test these ideas, we placed same-sex individuals of Nicrophorus orbicollis (early to mid-summer breeder) and N. tomentosus (late summer to fall breeder) into an enclosure together with a 25–30 g mouse carcass (Mus musculus). We then video-recorded all behaviors, including neutral and aggressive interactions, for 13 h per trial (N = 14 trials). For each interaction, we assigned a winner based on which beetle retained its position instead of fleeing or retained possession of the carcass; the overall behavioral dominant was determined as the individual that won the most interactions over the length of the trial. We found that large body size was the best predictor of behavioral dominance. In most interactions, N. orbicollis was larger and dominant over N. tomentosus; however, when N. tomentosus was larger they outcompeted smaller N. orbicollis, illustrating the importance of body size in aggressive contests. The order of arrival to the carcass (priority effects) did not predict behavioral dominance. The larger size and abundance of N. orbicollis in nature suggest a competitive asymmetry between the species, supporting the idea that N. orbicollis constrains the ability of N. tomentosus to breed earlier in the summer.

Thermal Inactivation of Carcasses of Mice and Rabbits Infected with Pathogens of Risk Groups Two to Four.

Pathogenesis of viruses or other agents that are infectious to humans is frequently studied in vivo using natural or genetically modified animals. Depending on the risk group of the pathogen, the majority of such experimental studies are performed at least under biosafety level 2 (BSL-2) conditions. Biosafety considerations are therefore critical at all steps of research involving potentially infectious pathogens. Inactivation of pathogens studied using in vitro experiments is usually performed using moist heat sterilization. However, few standardized and validated protocols are currently available for the thermal inactivation of carcasses from laboratory animals infected with such human pathogens. To comply with laboratory biologic safety rules and requirements imposed by regulatory authorities, documentation of appropriate inactivation conditions or use of a validated procedure according to national or international standards is critical. In the current study, we evaluated inactivation protocols in a standard laboratory autoclave for carcasses of either frozen mice or recently terminated rabbits, which were placed inside autoclave bags with bedding material in stainless steel containers. Temperature sensors were placed into different tissues of the carcasses to continuously record temperature in situ and in real-time, and a reference sensor was placed in the autoclave. To achieve pathogen inactivation, autoclaving protocols had to be optimized for both species. Frozen mice required 2 different fractionated prevacuum stages, whereas recently terminated rabbits required 3 different fractionated prevacuum stages. This study provides a template for an evaluation procedure to safely and effectively inactivate mice and rabbits infected with risk group 2 to 4 pathogens.

Olfactory Choice for Decomposition Stage in the Burying Beetle Nicrophorus vespilloides: Preference or Aversion?

Simple SummaryIn the burying beetle Nicrophorus vespilloides, mating pairs raise their offspring together on a small carrion resource. We tested whether carcass age affected brood quantity and quality and found that pairs had significantly more offspring on fresher carcasses. To determine whether this reproductive benefit translates to an olfactory preference or aversion for carcass age, we conducted a series of olfactory trials testing adult mated female preferences for carcasses differing in age. Mated females spent more time associating with fresh carcass odors relative to those of an aged one, but also spent more time in empty chambers than those with an aged carcass, suggesting that mated females have a general aversion to those odors. Lastly, we characterized the odor profiles of fresh and aged carcasses to determine which compounds might be driving this olfactory aversion in mated female burying beetles.Sensory cues predicting resource quality are drivers of key animal behaviors such as preference or aversion. Despite the abundance of behavioral choice studies across the animal kingdom, relatively few studies have tested whether these decisions are driven by preference for one choice or aversion to another. In the burying beetle Nicrophorus vespilloides, adult pairs exhibit parental care to raise their offspring on a small carrion resource. We tested whether carrion decomposition stage affected brood quantity and quality and found that mating pairs had significantly more offspring on fresher carcasses. To determine whether this observed reproductive benefit correlates with maternal preference behavior, we conducted a series of olfactory trials testing mated female preferences for mouse carcasses of differing decomposition stages. When given the option between fresh and older carcasses, females associated significantly more with fresher, 1-day old carcasses. However, this behavior may be driven by aversion, as females that were given a choice between the 7-day old carcass and a blank control spent significantly more time in the control chamber. We characterized volatile organic compound profiles of both carcass types, highlighting unique compounds that may serve as public information (sensu lato) conveying resource quality information to gravid beetles.

A synergism between dimethyl trisulfide and methyl thiolacetate in attracting carrion-frequenting beetles demonstrated by use of a chemically-supplemented minimal trap

Volatile organic compounds derived from microbes recruit insects to carrion, shaping community assembly and ecological succession. The importance of individual volatiles and interactions between volatiles are difficult to assess in the field because of (1) the myriad compounds from decomposing animals and (2) the likelihood that complex volatile blends are important for the final approach to carrion. On the assumption that searching carrion-frequenting beetles may use simpler cues to orient at a distance, we employed a chemically-supplemented minimal trap that uses test chemicals associated with active decay to attract from a distance and a minimal carrion bait (a small fresh mouse carcass) to induce trap entry. Traps supplemented with both methyl thiolacetate (MeSAc) and dimethyl trisulfide (DMTS) attracted greater numbers of beetles including adult silphids (Necrophila americana and Oiceoptoma noveboracense) and the histerid Euspilotus assimilis than the combined totals of DMTS-only and MeSAc-only traps, demonstrating a synergism. The attraction of larval Necrophila americana to traps left in the field for less than 24 h suggests that larvae move between carrion sources. The use of such species for forensic applications requires caution.

The fate of small-mammal carrion is affected by carcass size and visual conspicuousness in a Neotropical rainforest

Scavenging of carrion is essential to terrestrial ecosystems and can shape food webs and behavior. The prevalence and importance of scavenging has often been underestimated and overlooked in food web studies. Small-mammal carrion is even less studied and difficult to estimate, especially in the Neotropics. This project explored small-mammal carcass scavenging in a Neotropical, mid-elevation rainforest, and specifically studied the rate of carcass removal by scavengers, how the conspicuousness and weight of carcasses affect scavenging, and what vertebrate scavengers utilize this carrion resource. I deployed 194 mouse carcasses of various weights, above and below the leaf litter, and surveyed them daily until disappearance. I paired each carcass with a trail camera to help identify vertebrate scavengers. A general linear model analysis showed that most mouse carcasses disappeared within 1 to 2 days. Carcasses above the leaf litter were removed quicker and larger mice generally lasted longer. Only 6.25 % of the carcasses were removed by vertebrates. Most carcasses were removed by something too small to trigger the trail cameras, likely scarab beetles. The results of this study show that small-mammal carcasses are a sought-after resource in Neotropical forests, and that invertebrates are able to quickly hoard and secure small carrion more efficiently than vertebrate scavengers. A better understanding of scavenging ecology in Neotropical forests will help in developing a broader framework of the trophic interactions within and across ecosystems.

A study of insect succession of forensic importance: Dipteran flies (diptera) in two different habitats of small rodents in Riyadh City, Saudi Arabia

This study focused on comparing between dipteran fauna recovered from small mice (Mus musculus Linnaeus, 1758) and albino rat (Rattus norvegicus Berkenhout, 1769) carcasses placed in different habitats (a botanical garden and on a over the roof of 3rd floor of the faculty of science‘s building in the university campus). It was conducted during winter 2018 in Al-Dir'iya, Riyadh, Saudi Arabia. Collected specimens were identified morphologically and by molecular techniques based on the mitochondrial cytochrome oxidase subunit I (COI) gene. The number of flies recovered from the different decomposition stages of rat and mice carcasses at the two study sites was 5244, representing 11 families and 14 species. A tota nol of 4665 flies, comprising 11 families and 14 species, invaded carcasses located in the botanical garden, compared to the carcasses placed on the rooftop, which attracted 579 flies from 6 families and 9 species. The most abundant species recovered from both sites was Chrysomya albiceps (Wiedemann, 1830), followed by Musca domestica (Linnaeus, 1758), suggesting that these species are the most valuable for estimating Post Mortem intervals (PMIs) in this region of the Kingdom of Saudi Arabia. The data collected from this research can serve as the baseline data for homicide investigation as these flies can help determine PMI.

Smart forensic kit: Real-time estimation of postmortem interval using a highly sensitive gas sensor for microbial forensics

Microbial forensics, exploiting bacteria, archaea, and eukaryotes, has been considered as one of the primary fields to trace the postmortem interval from the decaying cadavers. On the other hand, there remain several challenges of laboratory-based analysis for prediction of postmortem interval, including long-time measurement, complicated measuring procedure, and bacterial growth while carrying samples from the scene. Herein, we introduce the Smart Forensic Kit, which consists of a highly sensitive colorimetric gas sensor, a quality control algorithm, and a smartphone-based analysis method, to quantify the bacterial-derived ammonia gas in real-time. As a result, the estimation system of the postmortem interval has a superior selectivity to the ammonia gas with a detection limit of 38.7 ppb, response linearity to the target bacteria (Escherichia coli, Pseudomonas aeruginosa, and Pseudomonas putida), and short measuring time (10 min) with the maximum predicted postmortem interval from the mouse carcass (168 h). Furthermore, thanks to measuring the postmortem interval within 10 min, the negligible increase rate of bacterial concentration was observed. Consequently, the results reflected a high correlation between the ammonia gas emitted from bacteria and the postmortem interval so that we believe the Smart Forensic Kit will be applied for tracing down the decomposition of the cadavers in the near future.

Protocol Improvement for RNA Extraction From Compromised Frozen Specimens Generated in Austere Conditions: A Path Forward to Transcriptomics-Pathology Systems Integration.

At the heart of the phenome-to-genome approach is high throughput assays, which are liable to produce false results. This risk can be mitigated by minimizing the sample bias, specifically, recycling the same tissue specimen for both phenotypic and genotypic investigations. Therefore, our aim is to suggest a methodology of obtaining robust results from frozen specimens of compromised quality, particularly if the sample is produced in conditions with limited resources. For example, generating samples at the International Space Station (ISS) is challenging because the time and laboratory footprint allotted to a project can get expensive. In an effort to be economical with available resources, snap-frozen euthanized mice are the straightforward solution; however, this method increases the risk of temperature abuse during the thawing process at the beginning of the tissue collection. We found that prolonged immersion of snap frozen mouse carcass in 10% neutral buffered formalin at 4°C yielded minimal microscopic signs of ice crystallization and delivered tissues with histomorphology that is optimal for hematoxylin and eosin (H&E) staining and fixation on glass slides. We further optimized a method to sequester the tissue specimen from the H&E slides using an incubator shaker. Using this method, we were able to recover an optimal amount of RNA that could be used for downstream transcriptomics assays. Overall, we demonstrated a protocol that enables us to maximize scientific values from tissues collected in austere condition. Furthermore, our protocol can suggest an improvement in the spatial resolution of transcriptomic assays.

First report of bullet ants (Paraponera clavata) sequestering vertebrate carrion

Facultative scavengers are important members of food webs that help shape trophic interactions. Unfortunately, the role of facultative scavengers is underestimated, in part, because we have not fully documented what organisms use carrion. As part of a scavenging project at La Selva Biological Station (Costa Rica), we observed bullet ants (Paraponera clavata) tearing apart and removing mouse carcasses. Of our 202 deployed mouse carcasses, we found bullet ants on 18 occasions. All of our bullet ant observations came from carcasses placed above-ground level (on lianas and branches; n = 100), and the majority of these were in primary forest. To our knowledge, this is the first report and description of bullet ants associating and removing carrion. We suspect that scavenging rates by bullet ants are likely higher than what we report here, and that bullet ants may be an important component of the scavenging communities in Neotropical rainforests.

Contribution of males to brood care can compensate for their food consumption from a shared resource.

The sharing of the same food source among parents and offspring can be a driver of the evolution of family life and parental care. However, if all family members desire the same meal, competitive situations can arise, especially if resource depletion is likely. When food is shared for reproduction and the raising of offspring, parents have to decide whether they should invest in self‐maintenance or in their offspring and it is not entirely clear how these two strategies are balanced. In the burying beetle Nicrophorus vespilloides, parents care for their offspring either bi‐ or uniparentally at a vertebrate carcass as the sole food source. The question of whether biparental care in this species offers the offspring a better environment for development compared with uniparental care has been the subject of some debate. We tested the hypothesis that male contribution to biparental brood care has a beneficial effect on offspring fitness but that this effect can be masked because the male also feeds from the shared resource. We show that a mouse carcass prepared by two Nicrophorus beetles is lighter compared with a carcass prepared by a single female beetle at the start of larval hatching and provisioning. This difference in carcass mass can influence offspring fitness when food availability is limited, supporting our hypothesis. Our results provide new insights into the possible evolutionary pathway of biparental care in this species of burying beetles.

Examining transmission of gut bacteria to preserved carcass via anal secretions in Nicrophorus defodiens.

Direct transmission of bacteria to subsequent generations highlights the beneficial nature of host-bacteria relationships. In insects, this process is often mediated by the production of microbe-containing secretions. The objective of this study was to determine if the burying beetle, Nicrophorus defodiens, utilizes anal secretions to transmit adult digestive tract bacteria onto a small vertebrate carcass; thus creating the potential to aid in carcass preservation or pass digestive tract bacteria to their larval offspring. Using high-throughput Illumina sequencing of the 16S rRNA gene, we characterized bacterial communities of adult beetle digestive tracts, their anal secretions, and prepared mouse carcasses. We also examined unprepared carcass bacterial communities as a means to interpret community shifts that take place during carcass preservation. We found a vast reduction in diversity on prepared carcasses after anal secretion application. Overall, there was little similarity in bacterial communities among adult digestive tracts, anal secretions, and prepared carcasses, suggesting bacterial communities found in adult digestive tracts do not successfully colonize and achieve dominance on prepared carcasses by way of beetle anal secretions. We concluded that N. defodiens does not transmit their digestive tract bacterial communities to prepared carcasses in a wholesale manner, but may transmit key microbes, including core microbiome members, to preserved carcasses that may ultimately act to sustain larvae and serve as inocula for larval digestive tracts.

A Study of 219Rn Outgassing and 211Pb Contamination from 223Ra In dry, Liquid, and Murine Tissue Samples.

A study of Pb contamination caused by the outgassing of Rn from Ra in dry, liquid, and murine tissues samples has been made to help design proper handling procedures for Ra in preclinical biodistribution work. Pb activity levels were measured from Ra in dry, liquid, and tissue samples using aspiration and autoradiography techniques. Using aspiration techniques on dry samples of Ra, an average Rn outgassing rate of 51% ± 21% was measured with one measurement reaching as high as 81%. 31% ± 4% Pb contamination was measured within a 4.3 cm radius of a dry Ra source placed inside a 10-cm-diameter petri dish where the lip of the petri dish contained the Rn dissemination. Without the containment of the petri dish, Rn can reach as far as 7.8 cm from the source with trace levels spreading further. Using aspiration techniques on liquid samples of Ra, outgassing rates of Rn were 0.9% ± 0.3%. The outgassing levels in harvested organs from a biodistribution were as high as 10.1% ± 0.4% for an intraperitoneally injected mouse and 0.204% ± 0.006% for an intravenously injected mouse. The outgassing of the intravenously injected mouse carcass was less than 0.1%. In dry form, the high levels of Rn outgassing from a Ra source necessitate the use of ventilated biohoods when handling or preparing dry Ra from source vials. The very low levels of Rn outgassing from Ra liquid sources reduces exposure to Rn by a factor of 50. Rn exposure from murine organ tissue reaches levels of 10% when handling organs from an intraperitoneal injection and less than 0.2% for an intravenous injection.

Delaying insect access alters community composition on small carrion: a quantitative approach

AbstractWe present a study of interactions in the highly competitive insect communities inhabiting the carrion of small mammals. Via manipulation in a fully quantitative design, we delayed community development by excluding insect colonization in mouse and rat carcasses for 3 days, to study the role of early competitively dominant colonizers [burying beetles (Nicrophorus spp.; Coleoptera: Silphidae) and blowfly larvae (Diptera: Calliphoridae)] in the course of heterotrophic succession on small cadavers. Earlier studies demonstrated that in the case of large mammalian carrion, exclusion of insects’ access to the carcass in the early stages of decomposition altered the successional trajectory and species assemblages. However, the effect of such manipulation in easy monopolizable small vertebrate carrion remained unknown. Our results demonstrate that delaying insect access to carrion significantly lowered blowfly larvae abundances, while it simultaneously had no effect on colonization and carrion burial by burying beetles. Higher abundances of blowfly larvae seem to deter necrophagous beetles, whereas they are not harmful to the larvae of flesh flies, at least in larger rat carcasses. Predatory beetle species preferred the lower abundances of blowfly larvae, presumably due to better accessibility of their prey. Our results therefore suggest that in the course of the entire season, larvae of blowflies are the dominant competitors in small carcasses, and significantly affect the assembly of other insect groups, whereas burying beetles may exhibit a more temporal pattern of dominance.