Associations formed between plants and arbuscular mycorrhizal (AM) fungi are characterized by the bi-directional exchange of fungal-acquired soil nutrients for plant-fixed organic carbon compounds. ...Mycorrhizal-acquired nutrient assimilation by plants may be symmetrically linked to carbon (C) transfer from plant to fungus or governed by sink-source dynamics. Abiotic factors, including atmospheric CO2 concentration (CO2), can affect the relative cost of resources traded between mutualists, thereby influencing symbiotic function. Whether biotic factors, such as insect herbivores that represent external sinks for plant C, impact mycorrhizal function remains unstudied. By supplying 33P to an AM fungus (Rhizophagus irregularis) and 14CO2 to wheat, we tested the impact of increasing C sink strength (i.e., aphid herbivory) and increasing C source strength (i.e., elevated CO2) on resource exchange between mycorrhizal symbionts. Allocation of plant C to the AM fungus decreased dramatically following exposure to the bird cherry-oat aphid (Rhopalosiphum padi), with high CO2 failing to alleviate the aphid-induced decline in plant C allocated to the AM fungus. Mycorrhizal-mediated uptake of 33P by plants was maintained regardless of aphid presence or elevated CO2, meaning insect herbivory drove asymmetry in carbon for nutrient exchange between symbionts. Here, we provide direct evidence that external biotic C sinks can limit plant C allocation to an AM fungus without hindering mycorrhizal-acquired nutrient uptake. Our findings highlight the context dependency of resource exchange between plants and AM fungi and suggest biotic factors—individually and in combination with abiotic factors—should be considered as powerful regulators of symbiotic function.
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•We tested how aphid herbivory and increasing CO2 affects wheat mycorrhizal function•Aphids reduced wheat C supply to mycorrhizal fungi. High CO2 had no effect.•Transfer of fungal 33P to plant was maintained regardless of aphids or high CO2•Mycorrhizal function is context dependent, affected by biotic and abiotic factors
Little is known about how mycorrhizal function is affected by insect herbivory and environment. Charters et al. show aphids reduce plant C allocation to mycorrhizas, although fungal P transfer to plants is maintained, suggesting high context dependency where resource exchange between symbionts is influenced by interacting biotic and abiotic factors.
1. The 20th century saw dramatic increases in agricultural productivity, largely through the development and application of pesticides, fertilisers rich in nitrogen and phosphorus, and advances in ...plant breeding and genetic technologies. In the last 15 years, however, many key crop yields have plateaued. Climate change, an ever-increasing human population, depletion of global rock-phosphorus and growing energy prices make current fertiliser production unsustainable and represent sizeable challenges to global food security. 2. Many important crops form symbioses with arbuscular mycorrhizal fungi (AMF), and this has motivated the development of novel approaches in crop breeding and agricultural practices to support and promote AMF in agroecosystems. 3. Arbuscular mycorrhizal fungal symbiosis can be high beneficial in crops and wider agroecosystems in many ways, including improved soil structure and resistance to pests. However, AMF colonisation does not necessarily translate directly into enhanced plant performance or crop yield, while land management practices that would encourage mycorrhiza-crop associations, such as lowtill or minimal chemical input often incur yield-reducing trade-offs. 4. Synthesis. We draw on ecological knowledge of AMF to inform their role in agroecosystems, providing a balanced look at mycorrhiza-crop symbioses in terms of plant ecophysiology and the wider role of AMF in agroecosystems and ask the question: are AMF our sustainable saviours?
The Comprehensive Care for Joint Replacement Model, developed by Centers for Medicare and Medicaid Services, aims to improve the quality of joint replacement. Metrics including emergency room visit ...rates after primary total knee and total hip arthroplasty (TKA and THA) are of particular interest. The purpose of this study is to determine if preoperative emergency department (ED) visits are predictive of postoperative ED visits among patients undergoing elective THA or TKA.
In a retrospective analysis of 6996 patients who underwent elective primary arthroplasty (2453 hips, 4543 knees), we identified all patients who had an ED visit from up to 1 year prior to their surgical date to 90 days after. We assessed if preoperative visit frequency or temporality is predictive of a return to the ED visit within 90 days.
TKA and THA patients with a single preoperative ED visit had an odds ratio of 1.9 and 2.0, respectively, of returning to the emergency room postoperatively (P < .001). Increasing preoperative visit frequency correlated with increasing odds ratios (1.9-16.7, P < .001). The proximity of the most recent preoperative visit prior to surgery had a positive trend toward a larger effect, but did not clearly demonstrate a dose-dependent effect.
Presentation to the ED is common prior to total joint arthroplasty and is predictive of a postoperative visit within 90 days. Increasing preoperative visit frequency further increases a patient’s risk of a postoperative visit within 90 days.
Societal Impact Statement
The Earth's population is projected to rise to 9.7 billion by 2050 resulting in mounting pressure to increase agricultural yields in a sustainable manner. Arbuscular ...mycorrhizal (AM) fungi may be important players in this agricultural transition given their capacity to improve soil and plant health. Benefits gained by crops hosting AM fungi can be cultivar‐specific and also affected by insect herbivory, although the combined effect of these factors remains unclear. Here, we show that, in an economically and socially significant tri‐partite system, there is interplay between crop cultivar, AM colonisation and aphid herbivory on plant growth and nutritional status.
Summary
Arbuscular mycorrhizal (AM) fungi are critical components of the rhizosphere across nearly all terrestrial biomes. AM fungi associate with most plants, including major crops, usually increasing plant access to soil nutrients and enhancing defence against pests and pathogens in return for photosynthetic carbon (C). However, plant growth responses to AM fungi vary according to species and genotype, an issue pertinent in agro‐ecosystems where crop cultivar can play an important role in AM function. Evidence suggests other biotic interactions, including with sap‐feeding aphids, impact the function of AM symbioses in plants. Nonetheless, whether these biotic factors alter genotype (or cultivar)‐specific plant growth and nutritional responses to colonisation by AM fungi remains unclear.
Here, we investigated whether mycorrhizal responsiveness of three cultivars of wheat (Triticum eastivum L.) to colonisation by a ubiquitously occurring AM fungus (Rhizophagus irregularis) differ in the presence or absence of bird cherry‐oat aphids (Rhopalosiphum padi), a major pest of cereals.
Our findings show that although AM fungal colonisation and AM‐mediated plant growth responses were not affected by aphid feeding, there was variation between cultivars in the benefits gained by host plants in terms of nutrient acquisition and root growth, while aphid abundances also differed between wheat varieties.
Understanding what causes cultivar‐specific outcomes and how they ultimately impact plant growth promotion, crop yields and food production represent key future research goals in agroecology.
The Earth's human population is projected to rise to 9.7 billion by 2050 resulting in mounting pressure to increase agricultural yields in a sustainable manner. Arbuscular mycorrhizal (AM) fungi may be important players in this agricultural transition given their capacity to improve soil and plant health. Benefits gained by crops hosting AM fungi can be cultivar‐specific and also affected by insect herbivory, although the combined effect of these factors remains unclear. Here, we show that, in an economically and socially significant tri‐partite system, there is interplay between crop cultivar, AM colonisation and aphid herbivory on plant growth and nutritional status.
The yellow early marsh orchid (Dactylorhiza incarnata ssp. ochroleuca) is a critically endangered terrestrial orchid in Britain. Previous attempts to translocate symbiotic seedlings to a site near ...the last remaining wild site demonstrated some success, with a 10% survival rate despite adverse weather conditions over a two-year period. However, to facilitate future reintroduction efforts or conservation translocations, a more comprehensive understanding of the fungal microbiome and abiotic soil characteristics at the final remaining wild site is required. Obtaining comprehensive information on both the fungal community and soil nutrient composition from wild sites has significant benefits and may prove critical for the success of future conservation translocations involving threatened orchids. This preliminary study, conducted at the last remaining wild site, revealed a significant correlation between the relative abundance of the orchid mycorrhizal fungal order Cantharellales and the concentrations of nitrate and phosphate in the soil. Another orchid mycorrhizal fungal group, Sebacinales, was found to be distributed extensively throughout the site. The composition of fungal communities across the entire site, orchid-hosting and non-orchid-hosting soils is discussed in relation to reinforcing the current population and preventing the extinction of this orchid.
Abstract Perioperative patient optimization can minimize the need for blood transfusions in patients undergoing total hip arthroplasty (THA) and total knee arthroplasty (TKA). The purpose of this ...study was to determine predictors and complications of transfusions. This retrospective review analyzed 1795 patients who underwent primary THA and TKA at our institution between January 2011 and December 2012. Of the 1573 patients ultimately included the rates of transfusion were 9.27% in TKA and 26.6% in THA. Significant predictors for transfusion include: preoperative hemoglobin, age, female gender, body mass index, creatinine, TKA, operating room time, operative blood loss, and intra-operative fluids. The DVT rate was comparable, but deep surgical site infection rate among transfused patients was 2.4% compared to 0.5% in non-transfused patients (P = 0.0065).
Abstract Intraoperative periprosthetic femur fracture is a known complication of total hip arthroplasty (THA) and a variety of cerclage systems are available to manage these fractures. The purpose of ...this study was to examine the in situ biomechanical response of cerclage systems for fixation of periprosthetic femur fractures that occur during cementless THA. We compared cobalt chrome (CoCr) cables, synthetic cables, monofilament wires and hose clamps under axial compressive and torsional loading. Metallic constructs with a positive locking system performed the best, supporting the highest loads with minimal implant subsidence (both axial and angular) after loading. Overall, the CoCr cable and hose clamp had the highest construct stiffness and least reduction in stiffness with increased loading. They were not demonstrably different from each other.
Abstract The oral Factor Xa inhibitor rivaroxaban (Xarelto) has been the pharmacologic agent used for venous thromboembolism (VTE) prophylaxis after primary hip and knee arthroplasty (THA/TKA) at our ...institution since February 2012. The purpose of our study was to compare rates of VTE and major bleeding between rivaroxaban and our previous protocol of enoxaparin after THA/TKA. A retrospective cohort study was performed including 2406 consecutive patients at our institution between 1/1/11 and 9/30/13. Patients who did not have unilateral primary THA/TKA or who received other anticoagulants were excluded. Of the 1762 patients included, 1113 patients (63.2%) received enoxaparin and 649 patients (36.8%) received rivaroxaban. This study found no demonstrable differences between these two anticoagulants in rates of VTE, infection, reoperation, transfusion, or major bleeding. Therapeutic, Retrospective comparative study, Level III.
Venous thromboembolism is a well-established complication of total hip and knee arthroplasty and hip fracture surgery. Clinical practice guidelines have been proposed to help clinicians provide ...prophylaxis against this risk. However, most guidelines reference data that are becoming outdated because of new advances in perioperative protocols. Recent data would suggest that aspirin may be appropriate for most patients after total hip and knee replacement and a more potent chemoprophylaxis for higher risk patients. Low-molecular-weight heparin remains the recommended choice after hip fracture surgery, although there is a paucity of recent literature in this patient population. There are randomized trials currently underway in the arthroplasty population that may guide clinicians in the appropriate choice of chemoprophylaxis. These studies should inform updates to the current clinical practice guidelines.
Background. Human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) can show variable clinical trajectories. Previous longitudinal studies of HAND typically have been brief, did ...not use adequate normative standards, or were conducted in the context of a clinical trial, thereby limiting our understanding of incident neurocognitive (NC) decline and recovery. Methods. We investigated the incidence and predictors of NC change over 16–72 (mean, 35) months in 436 HIV-infected participants in the CNS HIV Anti-Retroviral Therapy Effects Research Cohort. Comprehensive laboratory, neuromedical, and NC assessments were obtained every 6 months. Published, regression-based norms for NC change were used to generate overall change status (decline vs stable vs improved) at each study visit. Survival analysis was used to examine the predictors of time to NC change. Results. Ninety-nine participants (22.7%) declined, 265 (60.8%) remained stable, and 72 (16.5%) improved. In multivariable analyses, predictors of NC improvements or declines included time-dependent treatment status and indicators of disease severity (current hematocrit, albumin, total protein, aspartate aminotransferase), and baseline demographics and estimated premorbid intelligence quotient, non-HIV-related comorbidities, current depressive symptoms, and lifetime psychiatric diagnoses (overall model P < .0001). Conclusions. NC change is common in HIV infection and appears to be driven by a complex set of risk factors involving HIV disease, its treatment, and comorbid conditions.
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