Papers by Amanda B. Daly
Agriculture is a predominant land use and thus a large influence on global carbon (C) and nitroge... more Agriculture is a predominant land use and thus a large influence on global carbon (C) and nitrogen (N) balances, climate, and human health. If we are to produce food, fiber, and fuel sustainably we must maximize agricultural yield while minimizing negative environmental consequences, goals towards which we have made great strides through agronomic advances. However, most agronomic strategies have been designed with a view of soil as a black box, largely ignoring the way management is mediated by soil biota. Because soil microbes play a central role in many of the processes that deliver nutrients to crops and support their health and productivity, agricultural management strategies targeted to exploit or support microbial activity should deliver additional benefits. To do this we must determine how microbial community structure and function are shaped by agricultural practices, but until recently our characterizations of soil microbial communities in agricultural soils have been larg...
Biogeochemistry
Soil organic nitrogen (N) is a critical resource for plants and microbes, but the processes that ... more Soil organic nitrogen (N) is a critical resource for plants and microbes, but the processes that govern its cycle are not well-described. To promote a holistic understanding of soil N dynamics, we need an integrated model that links soil organic matter (SOM) cycling to bioavailable N in both unmanaged and managed landscapes, including agroecosystems. We present a framework that unifies recent conceptual advances in our understanding of three critical steps in bioavailable N cycling: organic N (ON) depolymerization and solubilization; bioavailable N sorption and desorption on mineral surfaces; and microbial ON turnover including assimilation, mineralization, and the recycling of microbial products. Consideration of the balance between these processes provides insight into the sources, sinks, and flux rates of bioavailable N. By accounting for interactions among the biological, physical, and chemical controls over ON and its availability to plants and microbes, our conceptual model un...
Priming, or the upregulation of soil organic matter (SOM) turnover by microbes in response to lab... more Priming, or the upregulation of soil organic matter (SOM) turnover by microbes in response to labile substrate inputs (e.g. from plant roots), could constitute an important control on nitrogen (N) cycling and, ultimately, plant N acquisition in agroecosystems. However, the plant-microbe controls on priming are not well-understood. I propose to determine: 1) To what extent plants can supply themselves with N by exploiting microbial responses to priming, 2) Whether plant-associated arbuscular mycorrhizal fungi (AMF) can induce priming effects, and if so, whether AMF community composition matters, and 3) How different soil microbial communities respond structurally and functionally to the influence of roots and AMF. I here present my plans to address these questions using soil from in-growth cores installed in May 2013 at the Rock Springs Agricultural Experiment Station at Penn State University. Cores constructed from different mesh sizes allow in-growth of roots and AMF (2 mm), AMF on...
Background/Question/Methods Mineralization of soil organic matter (SOM) by microbes supplies the ... more Background/Question/Methods Mineralization of soil organic matter (SOM) by microbes supplies the majority of plant nitrogen (N) in agroecosystems; however, the plant-microbe controls on N mineralization are not well-understood. Roots and associated arbuscular mycorrhizal fungi (AMF) could alter N mineralization dynamics by influencing rhizosphere and hyphosphere microbial community structure and function. This project seeks to determine the extent to which roots and AMF can alter N mineralization by soil microbes, and whether the functional response to root and AMF presence differs in soils with contrasting background microbial communities due to differences in agricultural management. Soil cores were constructed from mesh allowing in-growth of roots and AMF, AMF only, or no in-growth, and installed between maize plants under two agricultural management regimes of contrasting intensity with four replicate plots per treatment. Soil cores were destructively harvested after 42 and 84 d...
Crop Science, 2014
C limate change is representative of many of the "grand challenges" facing agriculture and the en... more C limate change is representative of many of the "grand challenges" facing agriculture and the environment-it is complex, spans traditional disciplinary boundaries, and is both a consequence and driver of coupled physical, biological, and socioeconomic processes acting at multiple spatial and temporal scales (Godfray et al., 2010; Collins et al., 2011; Foley et al., 2011). Researchers have recognized the need for more integrated and multifaceted approaches to examining such challenges, and funding agencies are increasingly investing in the creation of large, multidisciplinary research centers and longer-term (i.e., >3 yr) integrated research projects (Robertson and Swinton, 2005; Reganold et al., 2011). Examples of such integrated and transdisciplinary programs include USDA NIFA's Agriculture and
… Journal of Respiratory and Critical Care …, 2010
University of Vermont, Burlington, United States of America, University of Vermont, Burlington, V... more University of Vermont, Burlington, United States of America, University of Vermont, Burlington, VT, United States of America, Emory 1 ... University, Atlanta, GA, United States of America, Health Sciences Research Facility / University of Vermont, Burlington, VT, ...
Biomaterials, 2014
Acellular whole human lung scaffolds represent a unique opportunity for ex vivo tissue engineerin... more Acellular whole human lung scaffolds represent a unique opportunity for ex vivo tissue engineering. However, it remains unclear whether lungs from individuals with chronic lung diseases such as chronic obstructive pulmonary disease (COPD) can be appropriately decellularized and recellularized. To assess this, cadaveric human lungs from normal (nonsmoking) patients and from patients with COPD (smoking history) were decellularized and found by histochemical and immunohistochemical staining, electron microscopy, and mass spectrometry to retain characteristic histological architecture and extracellular matrix components (ECM) reflecting either normal or COPD, particularly emphysematous, origin. Inoculation of human bronchial epithelial cells, endothelial progenitor cells, bone marrow-derived mesenchymal stem cells, and lung fibroblasts via airway or vascular routes into small, excised segments of the decellularized lungs demonstrated that normal lung scaffolds robustly supported initial engraftment and growth of each cell type for up to one month. In contrast, despite initial binding, all cell types inoculated into decellularized emphysematous lungs did not survive beyond one
1. Caste determination in eusocial insects is the process by which individuals differentiate into... more 1. Caste determination in eusocial insects is the process by which individuals differentiate into reproducer or helper phenotypes. 2. Environmental caste determination (ECD) is predicted to be more efficient than genetic caste determination (GCD), yet GCD occurs in several populations of Pogonomyrmex harvester ants. 3. We tested whether GCD reduces efficiency by comparing colony growth rates of two GCD lineage pairs (H and J) with two closely related ECD congeners, P. rugosus and P. barbatus, under laboratory conditions over a range of temperatures. In addition, we directly compared metabolic rates of GCD and ECD larvae using flow-through respirometry. 4. Unexpectedly, colonies from GCD lineages grew faster than colonies of P. rugosus across all temperatures, and grew at the same rate as colonies of P. barbatus. Slower colony growth rates of P. rugosus were caused by lower queen fecundity and slower larval development. Variation in developmental rate was not due to differences in larval metabolic rates, which did not differ among taxa. 5. These results suggest that GCD in Pogonomyrmex does not impose significant productivity costs during colony growth. Instead, efficiency costs are compensated by other physiological mechanisms which may or may not be directly related to the mode of caste determination. 6. Persistence of GCD populations in contact with ECD competitors likely stems from a life-history trade-off favouring different taxa across the geographic range of the complex: the slow growing but starvation-resistant P. rugosus dominates in resource-poor regions, while faster growing and competitive GCD populations predominate in more mesic habitats.
Talks by Amanda B. Daly
Poster Presentations by Amanda B. Daly
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Papers by Amanda B. Daly
Talks by Amanda B. Daly
Poster Presentations by Amanda B. Daly