Cover crops have the potential to be agricultural nitrogen (N) regulators that reduce leaching through soils and then deliver N to subsequent cash crops. Yet, regulating N in this way has proven ...difficult because the few cover crop species that are well-studied excel at either reducing N leaching or increasing N supply to cash crops, but they fail to excel at both simultaneously. We hypothesized that mixed species cover crop stands might balance the N fixing and N scavenging capabilities of individual species. We tested six cover crop monocultures and four mixtures for their effects on N cycling in an organically managed maize-soybean-wheat feed grain rotation in Pennsylvania, USA. For three years, we used a suite of integrated approaches to quantify N dynamics, including extractable soil inorganic N, buried anion exchange resins, bucket lysimeters, and plant N uptake. All cover crop species, including legume monocultures, reduced N leaching compared to fallow plots. Cereal rye monocultures reduced N leaching to buried resins by 90% relative to fallow; notably, mixtures with just a low seeding rate of rye did almost as well. Austrian winter pea monocultures increased N uptake in maize silage by 40 kg N ha-1 relative to fallow, and conversely rye monocultures decreased N uptake into maize silage by 40 kg N ha-1 relative to fallow. Importantly, cover crop mixtures had larger impacts on leaching reduction than on maize N uptake, when compared to fallow plots. For example, a three-species mixture of pea, red clover, and rye had similar maize N uptake to fallow plots, but leaching rates were 80% lower in this mixture than fallow plots. Our results show clearly that cover crop species selection and mixture design can substantially mitigate tradeoffs between N retention and N supply to cash crops, providing a powerful tool for managing N in temperate cropping systems.
Urbanization imperils agriculture by converting farmland into uncultivable impervious surfaces and other uses that limit land productivity. Despite the considerable loss of productive croplands due ...to historic urbanization in the United States, little is known about the locations and magnitudes of extant agricultural land still under threat of future urban expansion. In this study, we developed a spatially explicit machine learning-based method to predict urban development through 2040 under a business-as-usual scenario and explored its occurrence on existing farmland. We found that if urban development continues at the same pace as that between 2001 and 2016, by 2040, highly developed areas and low-density residential areas will increase by 9.5 and 21 million acres, respectively. This increase would result in 18 million acres of agricultural land lost, fragmented, or compromised (~2% of total agricultural lands in 2016), with the remainder of projected development occurring on other types of natural and semi-natural lands. Of the affected agricultural lands, 6.2 million acres (34%) would be converted to uncultivable urban uses and 12 million acres (66%) to low-density residential uses. Agricultural land losses are projected to be greatest in fast-growing regions such as Texas, California, and the Southeast, and on the outskirts of metropolitan areas across the country, especially in the Midwest, where agricultural lands are more concentrated. The losses as a percentage of existing agricultural lands are projected to be highest along the East Coast, where many urban areas are forecasted to expand onto a limited remaining pool of cultivable lands. These findings can help guide the efforts of local, state, and federal policymakers to reduce land use competition between urban and agricultural systems and mitigate the impacts of projected urban expansion.
Climate change is threatening the status quo of agricultural production globally. Perennial cropping systems could be a useful strategy to adapt agriculture to a changing climate. Current and future ...perennial row crop systems have many and varied applications and these systems can respond differently than annuals to agricultural challenges resulting from climate change, such as shifting ranges of plant, pathogen, and animal species and more erratic weather patterns. To capitalize on attributes of perennial systems that assist in our ability to adapt to a changing world, it is important we fully consider the component parts of agroecosystems and their interactions, including species, genotype and genotypic variance, environment and environmental variance, adaptive management strategies, and farm socioeconomics. We review the current state of perennial grain and oilseed crops for integration into row crop agriculture and summarize the potential for current and future systems to support multiple environmental benefits and adaptation to climate change. We then propose a plant breeding strategy that incorporates the complexity of common domestication traits as they relate to future perennial crop improvement and adaptation and highlight digital technologies that can advance these goals. Evaluation of genetic gain during the development of new perennial crops and systems can be improved using research designs that span an environmental gradient that captures the forecasted shift in climate for a region, which we demonstrate by reanalyzing existing data. Successful development and deployment of perennial crops as a climate adaptation strategy depends on grower adoption, scalability, and sustainable modifications to markets and supply chains.
Core Ideas
Many agronomic and horticultural crops are perennials, which survive for years or decades after establishment.
Perennial crops are uniquely positioned to reduce the impacts of changing climates on growers.
Perennial crops are uniquely positioned to increase the ecological and social benefits of agriculture.
Perennial grain and oilseeds must be able to withstand increasingly erratic weather and shifts in disease, weed, and pest pressures.
Perennial grains and oilseed crops will play a more important role in sustainable and profitable agricultural production in the future.
We describe a participatory co-learning exercise that can help elucidate and navigate the unique perspectives of farmers, researchers, Extension personnel, and other agricultural professionals ...engaged in managing complex systems. We developed the exercise to help a diverse advisory panel collaboratively identify and prioritize ecosystem services for measurement in an experiment on cover crop mixtures. Post-event evaluations were positive and suggest that the exercise is a useful tool for participatory research projects or Extension programs involving a diverse group of stakeholders and complex systems.
Chronic wasting disease (CWD) is a prion disease affecting cervids. CWD diagnosis is conducted through enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry (IHC) in retropharyngeal ...lymph nodes. Unfortunately, these techniques have limited sensitivity against the biomarker (CWD-prions). Two in vitro prion amplification techniques, real-time quaking-induced conversion (RT-QuIC) and protein misfolding cyclic amplification (PMCA), have shown promise in detecting CWD-prions in tissues and bodily fluids. Recent studies have demonstrated that RT-QuIC yields similar results compared to ELISA and IHC. Here, we analyzed 1003 retropharyngeal lymph nodes (RPLNs) from Texas white-tailed deer. PMCA detected CWD at a higher rate compared to ELISA/IHC, identified different prion strains, and revealed the presence of CWD-prions in places with no previous history. These findings suggest that PMCA exhibits greater sensitivity than current standard techniques and could be valuable for rapid and strain-specific CWD detection.
Despite over a half-century of recognizing fibrinolytic abnormalities after trauma, we remain in our infancy in understanding the underlying mechanisms causing these changes, resulting in ineffective ...treatment strategies. With the increased utilization of viscoelastic hemostatic assays (VHAs) to measure fibrinolysis in trauma, more questions than answers are emerging. Although it seems certain that low fibrinolytic activity measured by VHA is common after injury and associated with increased mortality, we now recognize subphenotypes within this population and that specific cohorts arise depending on the specific time from injury when samples are collected. Future studies should focus on these subtleties and distinctions, as hypofibrinolysis, acute shutdown, and persistent shutdown appear to represent distinct, unique clinical phenotypes, with different pathophysiology, and warranting different treatment strategies.
Genome-wide association studies (GWAS) have successfully identified common genetic variants that contribute to breast cancer risk. Discovering additional variants has become difficult, as power to ...detect variants of weaker effect with present sample sizes is limited. An alternative approach is to look for variants associated with quantitative traits that in turn affect disease risk. As exposure to high circulating estradiol and testosterone, and low sex hormone-binding globulin (SHBG) levels is implicated in breast cancer etiology, we conducted GWAS analyses of plasma estradiol, testosterone, and SHBG to identify new susceptibility alleles. Cancer Genetic Markers of Susceptibility (CGEMS) data from the Nurses' Health Study (NHS), and Sisters in Breast Cancer Screening data were used to carry out primary meta-analyses among ~1600 postmenopausal women who were not taking postmenopausal hormones at blood draw. We observed a genome-wide significant association between SHBG levels and rs727428 (joint β = -0.126; joint P = 2.09 × 10(-16)), downstream of the SHBG gene. No genome-wide significant associations were observed with estradiol or testosterone levels. Among variants that were suggestively associated with estradiol (P<10(-5)), several were located at the CYP19A1 gene locus. Overall results were similar in secondary meta-analyses that included ~900 NHS current postmenopausal hormone users. No variant associated with estradiol, testosterone, or SHBG at P<10(-5) was associated with postmenopausal breast cancer risk among CGEMS participants. Our results suggest that the small magnitude of difference in hormone levels associated with common genetic variants is likely insufficient to detectably contribute to breast cancer risk.
Chronic wasting disease (CWD) is a prion disease affecting farmed and free-ranging cervids. CWD is rapidly expanding across North America and its mechanisms of transmission are not completely ...understood. Considering that cervids are commonly afflicted by nasal bot flies, we tested the potential of these parasites to transmit CWD. Parasites collected from naturally infected white-tailed deer were evaluated for their prion content using the protein misfolding cyclic amplification (PMCA) technology and bioassays. Here, we describe PMCA seeding activity in nasal bot larvae collected from naturally infected, nonclinical deer. These parasites efficiently infect CWD-susceptible mice in ways suggestive of high infectivity titers. To further mimic environmental transmission, bot larvae homogenates were mixed with soils, and plants were grown on them. We show that both soils and plants exposed to CWD-infected bot homogenates displayed seeding activity by PMCA. This is the first report describing prion infectivity in a naturally occurring deer parasite. Our data also demonstrate that CWD prions contained in nasal bots interact with environmental components and may be relevant for disease transmission.
Synopsis
Nasal fly bots from chronic wasting disease-infected deer carry relevant levels of prion infectivity. The parasites potentially deposit their infectious cargo in environmental components, as soil and plants exposed to CWD-infected bot homogenates display seeding activity.
CWD prions can be detected in nasal fly bots using the protein misfolding cyclic amplification (PMCA) technique.
Nasal fly bots carry relevant quantities of CWD prion infectivity as evaluated by mouse bioassays.
Most of the CWD prions in nasal fly bots are located in their protective shells.
CWD-contaminated nasal fly bots can deposit their infectious cargo in soils and contaminate plants.
Nasal fly bots are potentially relevant vectors of CWD transmission.
Nasal fly bots from chronic wasting disease-infected deer carry relevant levels of prion infectivity. The parasites potentially deposit their infectious cargo in environmental components, as soil and plants exposed to CWD-infected bot homogenates display prion seeding activity.
Chronic wasting disease (CWD) prions cause fatal neuropathies in farmed and free-ranging cervids. The deposition of prions in natural and humanmade environmental components has been implicated as a ...major mechanism mediating CWD spread in wild and captive populations. Prions can be deposited in the environment through excreta, tissues, and carcasses from pre-clinical and clinical animals. Furthermore, burial of CWD-positive animals may reduce but not completely mitigate prion spread from carcasses into the surrounding environment. Here, we analyzed exhumed, decaying deer carcasses for the presence of CWD prions. By analyzing tongue tissues through the protein misfolding cyclic amplification (PMCA) technique, we were able to identify seven out of 95 exhumed white-tailed deer carcasses as CWD prions carriers. Confirmatory analyses were performed using the real-time quaking-induced conversion (RT-QuIC) technique. In addition, we evaluated the potential contamination of the pens that housed these animals by swabbing feeders and waterers. PMCA analyses of swabs confirmed CWD contamination on farming equipment. This work demonstrates the usefulness of PMCA to detect CWD prions in a variety of contexts, including exhumed/decaying tissues. In addition, this is the first report demonstrating swabbing coupled with PMCA as a method for the detection of prion seeding activity on naturally exposed surfaces. Considering that this study was focused on a single site, further studies should confirm whether prion amplification assays are useful to identify CWD prions not only in animals but also in the environment that contains them. IMPORTANCE Environmental contamination is thought to be a major player in the spread of chronic wasting disease (CWD), a fatal prion disease affecting a wide variety of cervid species. At present, there are no officially approved methods allowing for the detection of prion infectivity in environmental components. Importantly, animal as well as anthropogenic activities are thought to contribute to prion environmental contamination. Here, we detected CWD prions in exhumed white-tailed deer carcasses by using the protein misfolding cyclic amplification (PMCA) assay. In addition, we identified CWD prions in feeders used within the infected facility. These results highlight the potential role of PMCA in identifying prion infectivity in a variety of scenarios, ranging from decaying tissues to farming equipment.
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