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The article discusses results of organic residue analysis performed on ten copper-alloy daggers from Bronze Age Pragatto, Italy, c.1550-1250 BCE. Metal daggers are widespread in Chalcolithic and Bronze Age Europe, yet their social and practical roles are still hotly debated. Are they symbolic or functional? Are they tools or weapons? How were they used? For what tasks and on what materials? The research addresses these questions through a novel application of biochemical staining and SEM-EDX analysis. The method has proved successful in extracting and identifying animal residues located on cutting edges including bone, muscle, and tendons. These are interpreted as evidence of prehistoric carcass butchering and carving. Further residues were observed on blade faces and hafting plates or tangs; these are interpreted as remnants of bone handles and sheaths, the latter made of either wood fibers or processed hide and fur. The readings proposed in the article are validated by original experiments with replica daggers, as detailed in the Supplementary Materials. The analysis and experiments shed new light on Bronze Age metal daggers, showing that they were fully functional tools (and perhaps tool-weapons) primarily utilized for the processing of animal carcasses. This original research result contributes significant knowledge towards interpreting an under-studied, yet socially salient, prehistoric metal artifact., (© 2022. The Author(s).)

Plant-growth-promoting bacteria (PGPB) are used to improve plant health and promote crop production. However, because some PGPB (including Bacillus subtilis ) do not maintain substantial colonization on plant roots over time, it is unclear how effective PGPB are throughout the plant growing cycle. A better understanding of the dynamics of plant root community assembly is needed to develop and harness the potential of PGPB. Although B. subtilis is often a member of the root microbiome, it does not efficiently monoassociate with plant roots. We hypothesized that B. subtilis may require other primary colonizers to efficiently associate with plant roots. We utilized a previously designed hydroponic system to add bacteria to Arabidopsis thaliana roots and monitor their attachment over time. We inoculated seedlings with B. subtilis and individual bacterial isolates from the native A. thaliana root microbiome either alone or together. We then measured how the coinoculum affected the ability of B. subtilis to colonize and maintain on A. thaliana roots. We screened 96 fully genome-sequenced strains and identified five bacterial strains that were able to significantly improve the maintenance of B. subtilis . Three of these rhizobacteria also increased the maintenance of two strains of B. amyloliquefaciens commonly used in commercially available bioadditives. These results not only illustrate the utility of this model system to address questions about plant-microbe interactions and how other bacteria affect the ability of PGPB to maintain their relationships with plant roots but also may help inform future agricultural interventions to increase crop yields., Competing Interests: The author(s) declare no conflict of interest.

Universities should use online resources to help graduate students who are struggling with their mental health to access appropriate support., Competing Interests: LK, SH No competing interests declared, (© 2019, Krause and Harris.)

Bacteria form complex rhizosphere microbiomes shaped by interacting microbes, larger organisms, and the abiotic environment. Under laboratory conditions, rhizosphere colonization by plant growth-promoting bacteria (PGPB) can increase the health or the development of host plants relative to uncolonized plants. However, in field settings, bacterial treatments with PGPB often do not provide substantial benefits to crops. One explanation is that this may be due to loss of the PGPB during interactions with endogenous soil microbes over the lifespan of the plant. This possibility has been difficult to confirm, since most studies focus on the initial colonization rather than maintenance of PGPB within rhizosphere communities. It is hypothesized here that the assembly, coexistence, and maintenance of bacterial communities are shaped by deterministic features of the rhizosphere microenvironment, and that these interactions may impact PGPB survival in native settings. To study these behaviors, a hydroponic plant-growth assay is optimized using Arabidopsis thaliana to quantify and visualize the spatial distribution of bacteria during initial colonization of plant roots and after transfer to different growth environments. This system's reproducibility and utility are then validated with the well-studied PGPB Pseudomonas simiae. To investigate how the presence of multiple bacterial species may affect colonization and maintenance dynamics on the plant root, a model community from three bacterial strains (an Arthrobacter, Curtobacterium, and Microbacterium species) originally isolated from the A. thaliana rhizosphere is constructed. It is shown that the presence of these diverse bacterial species can be measured using this hydroponic plant-maintanence assay, which provides an alternative to sequencing-based bacterial community studies. Future studies using this system may improve the understanding of bacterial behavior in multispecies plant microbiomes over time and in changing environmental conditions.

Soil bacteria engage each other in competitive and cooperative ways to determine their microenvironments. In this study, we report the identification of a large number of genes required for Myxococcus xanthus to engage Bacillus subtilis in a predator-prey relationship. We generated and tested over 6,000 individual transposon insertion mutants of M. xanthus and found many new factors required to promote efficient predation, including the specialized metabolite myxoprincomide, an ATP-binding cassette (ABC) transporter permease, and a clustered regularly interspaced short palindromic repeat (CRISPR) locus encoding bacterial immunity. We also identified genes known to be involved in predation, including those required for the production of exopolysaccharides and type IV pilus (T4P)-dependent motility, as well as chemosensory and two-component systems. Furthermore, deletion of these genes confirmed their role during predation. Overall, M. xanthus predation appears to be a multifactorial process, with multiple determinants enhancing predation capacity., Importance: Soil bacteria engage each other in complex environments and utilize multiple traits to ensure survival. Here, we report the identification of multiple traits that enable a common soil organism, Myxococcus xanthus, to prey upon and utilize nutrients from another common soil organism, Bacillus subtilis We mutagenized the predator and carried out a screen to identify genes that were required to either enhance or diminish capacity to consume prey. We identified dozens of genes encoding factors that contribute to the overall repertoire for the predator to successfully engage its prey in the natural environment., (Copyright © 2016, American Society for Microbiology. All Rights Reserved.)

Objective: To describe the development and pilot testing of a set of admissions instruments based on the McMaster University multiple mini-interview (MMI) and designed to assess desirable, non-cognitive characteristics in order to inform final decisions on candidate selection for entry to medical school., Methods: Community and faculty consultation on desirable, non-cognitive characteristics of medical students informed the development of a 10-station interview. Two stations occurred as part of a group problem-based learning scenario and 8 occurred as individual observations. All interviewers were trained. Interviews were offered to 115 candidates on an academic merit list. Interview performance was used to exclude candidates considered unsuitable, but not to re-order the academic merit list. Admissions decisions were examined in terms of individual interview station performance., Results: This method proved to be an efficient process by which to interview candidates and to determine suitability. Retained and rejected candidates had significantly different total scores and mean scores for each station. Ten independent observations contributed to each decision, without significant interviewer or logistic burden. Candidates reported high levels of satisfaction with the interview process., Conclusions: Admissions interviews can be streamlined and efficient, yet remain informative. A longitudinal study is in progress to evaluate the value of the admissions processes in predicting successful graduation to medical practice.