The Effects of Aboveground Herbivory on Root Traits and Root Decomposition

Soil holds more carbon (C) than the Earth\u27s atmosphere and vegetation combined. Soil loses carbon through soil respiration and releases CO2 from the soil. The soil respiration rate can vary based on the chemistry of the plant litter inputs and physical factors, such as soil temperature and nutrient content. In Alaska\u27s Yukon-Kuskokwim (YK) Delta, grazing by geese affects the chemistry of plants and the soil\u27s physical qualities, thus altering the rate of soil respiration. Although we know that goose herbivory leads to changes in the rate of soil respiration, we know very little about how goose herbivory affects the inputs of plant roots. Roots are an important factor in soil respiration because roots contribute a substantial amount of C to the soil. This knowledge gap limits our ability to truly understand C cycling processes like root decomposition, which may influence soil respiration in the YK Delta. To better understand how goose herbivory affects root C and soil respiration, we collected C. subspathacea root samples, a common sedge in the YK Delta, from either grazed or ungrazed habitats to understand if goose herbivory creates intraspecific differences in their morphological (specific root length, root volume and root surface area), chemical (carbon: nitrogen ratio, %C, %nitrogen, %phosphorus and ADF), and physiological traits (root exudates). Additionally, we created a laboratory experiment to assess how goose herbivory affects root decomposition and C loss using weekly CO2 efflux as a proxy for the decomposition rate. Within this experiment, we manipulated root treatment by using roots that were either exposed to aboveground grazing or not, feces deposition (present/absent), and temperature to simulate the range of effects aboveground herbivory has on plant litter and soil physicochemical properties. In this study, we demonstrated that aboveground herbivory did not alter root morphology but affected root chemistry and exudation. Specifically, aboveground grazing led to lower C:N, higher %N, lower %C, %ADF (a measurement of cellulose and lignin), and a greater rate of root exudation. Although we did not see differences in root morphology, the differences in root chemistry and exudation are often associated with faster plant decomposition. Our root decomposition experiment confirmed that aboveground herbivory alters the rate of root decomposition and leads to increased C loss directly by altering indirectly by increasing soil temperatures and directly by altering root inputs. Our study demonstrates that aboveground herbivory can significantly alter root trait expression, which may increase the loss of C from the soil

Online learning for infectious disease fellows-A needs assessment

BACKGROUND: Online resources and social media have become increasingly ubiquitous in medical education. Little is known about the need for educational resources aimed at infectious disease (ID) fellows. METHODS: We conducted an educational needs assessment through a survey that aimed to describe ID fellows\u27 current use of online and social media tools, assess the value of online learning, and identify the educational content preferred by ID fellows. We subsequently convened focus groups with ID fellows to explore how digital tools contribute to fellow learning. RESULTS: A total of 110 ID fellows responded to the survey. Over half were second-year fellows (61, 55%). Although many respondents were satisfied with the educational resources provided by their fellowship program (70, 64%), the majority were interested in an online collaborative educational resource (97, 88%). Twitter was the most popular social media platform for education and the most valued online resource for learning. Focus groups identified several themes regarding social medial learning: broadened community, low barrier to learning, technology-enhanced learning, and limitations of current tools. Overall, the focus groups suggest that fellows value social media and online learning. CONCLUSIONS: ID fellows are currently using online and social media resources, which they view as valuable educational tools. Fellowship programs should consider these resources as complementary to traditional teaching and as a means to augment ID fellow education

Dental and craniofacial defects in the Crtap−/− mouse model of osteogenesis imperfecta type VII

BackgroundInactivating mutations in the gene for cartilage‐associated protein (CRTAP) cause osteogenesis imperfecta type VII in humans, with a phenotype that can include craniofacial defects. Dental and craniofacial manifestations have not been a focus of case reports to date. We analyzed the craniofacial and dental phenotype of Crtap−/− mice by skull measurements, micro‐computed tomography (micro‐CT), histology, and immunohistochemistry.ResultsCrtap−/− mice exhibited a brachycephalic skull shape with fusion of the nasofrontal suture and facial bones, resulting in mid‐face retrusion and a class III dental malocclusion. Loss of CRTAP also resulted in decreased dentin volume and decreased cellular cementum volume, though acellular cementum thickness was increased. Periodontal dysfunction was revealed by decreased alveolar bone volume and mineral density, increased periodontal ligament (PDL) space, ectopic calcification within the PDL, bone‐tooth ankylosis, altered immunostaining of extracellular matrix proteins in bone and PDL, increased pSMAD5, and more numerous osteoclasts on alveolar bone surfaces.ConclusionsCrtap−/− mice serve as a useful model of the dental and craniofacial abnormalities seen in individuals with osteogenesis imperfecta type VII.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155878/1/dvdy166.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155878/2/dvdy166_am.pd

Assistants, Guides, Collaborators, Friends: The Concealed Figures of Conflict Research

Recent scholarship has demonstrated an increasing awareness of the need for more grounded, empirical research into the micro-level dynamics of violent contexts. Research in these difficult, dangerous, and potentially violent conflict or post-conflict settings necessitates the formation of new relationships of dependency, and assistants, friends, collaborators, and guides become central figures in the field. However, all too often, these figures are written out of academic accounts and silenced in our analyses. This not only does them a significant disservice, but it also obscures potential biases, complexities, and ethical dilemmas that emerge in the way in which such research is carried out. Drawing upon fieldwork exploring the 2007–2008 Kenyan postelection violence, this paper argues that reliance upon insider-assistants is essential in conflict settings and explores the challenges inherent in these relationships. As researchers become increasingly engaged in micro-level studies of violent contexts, we must interrogate the realities of how our knowledge has been produced and engage in more open and honest discussions of the methodological and ethical challenges of conflict research

Engineering Genetic Predisposition in Human Neuroepithelial Stem Cells Recapitulates Medulloblastoma Tumorigenesis.

Human neural stem cell cultures provide progenitor cells that are potential cells of origin for brain cancers. However, the extent to which genetic predisposition to tumor formation can be faithfully captured in stem cell lines is uncertain. Here, we evaluated neuroepithelial stem (NES) cells, representative of cerebellar progenitors. We transduced NES cells with MYCN, observing medulloblastoma upon orthotopic implantation in mice. Significantly, transcriptomes and patterns of DNA methylation from xenograft tumors were globally more representative of human medulloblastoma compared to a MYCN-driven genetically engineered mouse model. Orthotopic transplantation of NES cells generated from Gorlin syndrome patients, who are predisposed to medulloblastoma due to germline-mutated PTCH1, also generated medulloblastoma. We engineered candidate cooperating mutations in Gorlin NES cells, with mutation of DDX3X or loss of GSE1 both accelerating tumorigenesis. These findings demonstrate that human NES cells provide a potent experimental resource for dissecting genetic causation in medulloblastoma

Systematic analysis of SARS-CoV-2 infection of an ACE2-negative human airway cell

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) variants govern transmissibility, responsiveness to vaccination, and disease severity. In a screen for new models of SARS-CoV-2 infection, we identify human H522 lung adenocarcinoma cells as naturally permissive to SARS-CoV-2 infection despite complete absence of angiotensin-converting enzyme 2 (ACE2) expression. Remarkably, H522 infection requires the E484D S variant; viruses expressing wild-type S are not infectious. Anti-S monoclonal antibodies differentially neutralize SARS-CoV-2 E484D S in H522 cells as compared to ACE2-expressing cells. Sera from vaccinated individuals block this alternative entry mechanism, whereas convalescent sera are less effective. Although the H522 receptor remains unknown, depletion of surface heparan sulfates block H522 infection. Temporally resolved transcriptomic and proteomic profiling reveal alterations in cell cycle and the antiviral host cell response, including MDA5-dependent activation of type I interferon signaling. These findings establish an alternative SARS-CoV-2 host cell receptor for the E484D SARS-CoV-2 variant, which may impact tropism of SARS-CoV-2 and consequently human disease pathogenesis

Measurement of the cosmic ray spectrum above 4×10184{\times}10^{18} eV using inclined events detected with the Pierre Auger Observatory

A measurement of the cosmic-ray spectrum for energies exceeding $4{\times}10^{18}$ eV is presented, which is based on the analysis of showers with zenith angles greater than $60^{\circ}$ detected with the Pierre Auger Observatory between 1 January 2004 and 31 December 2013. The measured spectrum confirms a flux suppression at the highest energies. Above $5.3{\times}10^{18}$ eV, the "ankle", the flux can be described by a power law $E^{-\gamma}$ with index $\gamma=2.70 \pm 0.02 \,\text{(stat)} \pm 0.1\,\text{(sys)}$ followed by a smooth suppression region. For the energy ($E_\text{s}$) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find $E_\text{s}=(5.12\pm0.25\,\text{(stat)}^{+1.0}_{-1.2}\,\text{(sys)}){\times}10^{19}$ eV.Comment: Replaced with published version. Added journal reference and DO

Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory

The Auger Engineering Radio Array (AERA) is part of the Pierre Auger Observatory and is used to detect the radio emission of cosmic-ray air showers. These observations are compared to the data of the surface detector stations of the Observatory, which provide well-calibrated information on the cosmic-ray energies and arrival directions. The response of the radio stations in the 30 to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of the incoming electric field. For the latter, the energy deposit per area is determined from the radio pulses at each observer position and is interpolated using a two-dimensional function that takes into account signal asymmetries due to interference between the geomagnetic and charge-excess emission components. The spatial integral over the signal distribution gives a direct measurement of the energy transferred from the primary cosmic ray into radio emission in the AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air shower arriving perpendicularly to the geomagnetic field. This radiation energy -- corrected for geometrical effects -- is used as a cosmic-ray energy estimator. Performing an absolute energy calibration against the surface-detector information, we observe that this radio-energy estimator scales quadratically with the cosmic-ray energy as expected for coherent emission. We find an energy resolution of the radio reconstruction of 22% for the data set and 17% for a high-quality subset containing only events with at least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO