College of Agriculture
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As the foundation of the land grant mission at Montana State University, the College of Agriculture and the Montana Agricultural Experiment Station provide instruction in traditional and innovative degree programs and conduct research on old and new challenges for Montana’s agricultural community. This integration creates opportunities for students and faculty to excel through hands-on learning, to serve through campus and community engagement, to explore unique solutions to distinct and interesting questions and to connect Montanans with the global community through research discoveries and outreach.
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Item Neutrophil Immunomodulatory Activity of (−)-Borneol, a Major Component of Essential Oils Extracted from Grindelia squarrosa(MDPI AG, 2022-07) Schepetkin, Igor A.; Özek, Gulmira; Özek, Temel; Kirpotina, Liliya N.; Khlebnikov, Andrei I.; Quinn, Mark T.Grindelia squarrosa (Pursh) Dunal is used in traditional medicine for treating various diseases; however, little is known about the immunomodulatory activity of essential oils from this plant. Thus, we isolated essential oils from the flowers (GEOFl) and leaves (GEOLv) of G. squarrosa and evaluated the chemical composition and innate immunomodulatory activity of these essential oils. Compositional analysis of these essential oils revealed that the main components were α-pinene (24.7 and 23.2% in GEOFl and GEOLv, respectively), limonene (10.0 and 14.7%), borneol (23.4 and 16.6%), p-cymen-8-ol (6.1 and 5.8%), β-pinene (4.0 and 3.8%), bornyl acetate (3.0 and 5.1%), trans-pinocarveol (4.2 and 3.7%), spathulenol (3.0 and 2.0%), myrtenol (2.5 and 1.7%), and terpinolene (1.7 and 2.0%). Enantiomer analysis showed that α-pinene, β-pinene, and borneol were present primarily as (−)-enantiomers (100% enantiomeric excess (ee) for (−)-α-pinene and (−)-borneol in both GEOFl and GEOLv; 82 and 78% ee for (−)-β-pinene in GEOFl and GEOLv), while limonene was present primarily as the (+)-enantiomer (94 and 96 ee in GEOFl and GEOLv). Grindelia essential oils activated human neutrophils, resulting in increased [Ca2+]i (EC50 = 22.3 µg/mL for GEOFl and 19.4 µg/mL for GEOLv). In addition, one of the major enantiomeric components, (−)-borneol, activated human neutrophil [Ca2+]i (EC50 = 28.7 ± 2.6), whereas (+)-borneol was inactive. Since these treatments activated neutrophils, we also evaluated if they were able to down-regulate neutrophil responses to subsequent agonist activation and found that treatment with Grindelia essential oils inhibited activation of these cells by the N-formyl peptide receptor 1 (FPR1) agonist fMLF and the FPR2 agonist WKYMVM. Likewise, (−)-borneol inhibited FPR-agonist-induced Ca2+ influx in neutrophils. Grindelia leaf and flower essential oils, as well as (−)-borneol, also inhibited fMLF-induced chemotaxis of human neutrophils (IC50 = 4.1 ± 0.8 µg/mL, 5.0 ± 1.6 µg/mL, and 5.8 ± 1.4 µM, respectively). Thus, we identified (−)-borneol as a novel modulator of human neutrophil function.Item Environmentally clean access to Antarctic subglacial aquatic environments(2020-10) Michaud, Alexander B.; Vick-Majors, Trista J.; Achberger, Amanda M.; Skidmore, Mark L.; Christner, Brent C.; Tranter, Martyn; Priscu, John C.Subglacial Antarctic aquatic environments are important targets for scientific exploration due to the unique ecosystems they support and their sediments containing palaeoenvironmental records. Directly accessing these environments while preventing forward contamination and demonstrating that it has not been introduced is logistically challenging. The Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) project designed, tested and implemented a microbiologically and chemically clean method of hot-water drilling that was subsequently used to access subglacial aquatic environments. We report microbiological and biogeochemical data collected from the drilling system and underlying water columns during sub-ice explorations beneath the McMurdo and Ross ice shelves and Whillans Ice Stream. Our method reduced microbial concentrations in the drill water to values three orders of magnitude lower than those observed in Whillans Subglacial Lake. Furthermore, the water chemistry and composition of microorganisms in the drill water were distinct from those in the subglacial water cavities. The submicron filtration and ultraviolet irradiation of the water provided drilling conditions that satisfied environmental recommendations made for such activities by national and international committees. Our approach to minimizing forward chemical and microbiological contamination serves as a prototype for future efforts to access subglacial aquatic environments beneath glaciers and ice sheets.Item Avian tail ontogeny, pygostyle formation, and interpretation of juvenile Mesozoic specimens(2018-06) Rashid, Dana J.; Surya, Kevin; Chiappe, Luis M.; Carroll, Nathan; Garrett, Kimball L.; Varghese, Bino; Bailleul, Alida M.; O'Connor, Jingmai K.; Chapman, Susan C.; Horner, John R.The avian tail played a critical role in the evolutionary transition from long- to short-tailed birds, yet its ontogeny in extant birds has largely been ignored. This deficit has hampered efforts to effectively identify intermediate species during the Mesozoic transition to short tails. Here we show that fusion of distal vertebrae into the pygostyle structure does not occur in extant birds until near skeletal maturity, and mineralization of vertebral processes also occurs long after hatching. Evidence for post-hatching pygostyle formation is also demonstrated in two Cretaceous specimens, a juvenile enantiornithine and a subadult basal ornithuromorph. These findings call for reinterpretations of Zhongornis haoae, a Cretaceous bird hypothesized to be an intermediate in the long- to short-tailed bird transition, and of the recently discovered coelurosaur tail embedded in amber. Zhongornis, as a juvenile, may not yet have formed a pygostyle, and the amber-embedded tail specimen is reinterpreted as possibly avian. Analyses of relative pygostyle lengths in extant and Cretaceous birds suggests the number of vertebrae incorporated into the pygostyle has varied considerably, further complicating the interpretation of potential transitional species. In addition, this analysis of avian tail development reveals the generation and loss of intervertebral discs in the pygostyle, vertebral bodies derived from different kinds of cartilage, and alternative modes of caudal vertebral process morphogenesis in birds. These findings demonstrate that avian tail ontogeny is a crucial parameter specifically for the interpretation of Mesozoic specimens, and generally for insights into vertebrae formation.Item Opportunities and Trade-offs among BECCS and the Food, Water, Energy, Biodiversity, and Social Systems Nexus at Regional Scales(2018-01) Stoy, Paul C.; Ahmed, Selena; Jarchow, Meghann; Rashford, Benjamin; Swanson, David; Albeke, Shannon; Bromley, Gabriel T.; Brookshire, E. N. Jack; Dixon, Mark D.; Haggerty, Julia Hobson; Miller, Perry R.; Peyton, Brent M.; Royem, Alisa; Spangler, Lee H.; Straub, Crista; Poulter, BenjaminCarbon dioxide must be removed from the atmosphere to limit climate change to 2°C or less. The integrated assessment models used to develop climate policy acknowledge the need to implement net negative carbon emission strategies, including bioenergy with carbon capture and storage (BECCS), to meet global climate imperatives. The implications of BECCS for the food, water, energy, biodiversity, and social systems (FWEBS) nexus at regional scales, however, remain unclear. Here, we present an interdisciplinary research framework to examine the trade-offs as well as the opportunities among BECCS scenarios and FWEBS on regional scales using the Upper Missouri River Basin (UMRB) as a case study. We describe the physical, biological, and social attributes of the UMRB, and we use grassland bird populations as an example of how biodiversity is influenced by energy transitions, including BECCS. We then outline a "conservation" BECCS strategy that incorporates societal values and emphasizes biodiversity conservation.Item Pinus contorta invasions increase wildfire fuel loads and may create a positive feedback with fire(2017-03) Taylor, Kimberley T.; Maxwell, Bruce D.; McWethy, David B.; Pauchard, Anibal; Nunez, Martin A.; Whitlock, CathyInvasive plant species that have the potential to alter fire regimes have significant impacts on native ecosystems. Concern that pine invasions in the Southern Hemisphere will increase fire activity and severity and subsequently promote further pine invasion prompted us to examine the potential for feedbacks between Pinus contorta invasions and fire in Patagonia and New Zealand. We determined how fuel loads and fire effects were altered by P. contorta invasion. We also examined post-fire plant communities across invasion gradients at a subset of sites to assess how invasion alters the post-fire vegetation trajectory. We found that fuel loads and soil heating during simulated fire increase with increasing P. contorta invasion age or density at all sites. However, P. contorta density did not always increase post-fire. In the largest fire, P. contorta density only increased significantly post-fire where the pre-fire P. contorta density was above an invasion threshold. Below this threshold, P. contorta did not dominate after fire and plant communities responded to fire in a similar manner as uninvaded communities. The positive feedback observed at high densities is caused by the accumulation of fuel that in turn results in greater soil heating during fires and high P. contorta density post-fire. Therefore, a positive feedback may form between P. contorta invasions and fire, but only above an invasion density threshold. These results suggest that management of pine invasions before they reach the invasion density threshold is important for reducing fire risk and preventing a transition to an alternate ecosystem state dominated by pines and novel understory plant communities.Item Microbial Community Structure of Subglacial Lake Whillans, West Antarctica(2016-09) Achberger, Amanda M.; Christner, Brent C.; Michaud, Alexander B.; Priscu, John C.; Skidmore, Mark L.; Vick-Majors, Trista J.Subglacial Lake Whillans (SLW) is located beneath 800 m of ice on the Whillans Ice Stream in West Antarctica and was sampled in January of 2013, providing the first opportunity to directly examine water and sediments from an Antarctic subglacial lake. To minimize the introduction of surface contaminants to SLW during its exploration, an access borehole was created using a microbiologically clean hot water drill designed to reduce the number and viability of microorganisms in the drilling water. Analysis of 16S rRNA genes (rDNA) amplified from samples of the drilling and borehole water allowed an evaluation of the efficacy of this approach and enabled a confident assessment of the SLW ecosystem inhabitants. Based on an analysis of 16S rDNA and rRNA (i.e., reverse-transcribed rRNA molecules) data, the SLW community was found to be bacterially dominated and compositionally distinct from the assemblages identified in the drill system. The abundance of bacteria (e.g., Candidatus Nitrotoga, Sideroxydans, Thiobacillus, and Albidiferax) and archaea (Candidatus Nitrosoarchaeum) related to chemolithoautotrophs was consistent with the oxidation of reduced iron, sulfur, and nitrogen compounds having important roles as pathways for primary production in this permanently dark ecosystem. Further, the prevalence of Methylobacter in surficial lake sediments combined with the detection of methanogenic taxa in the deepest sediment horizons analyzed (34-36 cm) supported the hypothesis that methane cycling occurs beneath the West Antarctic Ice Sheet. Large ratios of rRNA to rDNA were observed for several operational taxonomic units abundant in the water column and sediments (e.g., Albidiferax, Methylobacter, Candidatus Nitrotoga, Sideroxydans, and Smithella), suggesting a potentially active role for these taxa in the SLW ecosystem. Our findings are consistent with chemosynthetic microorganisms serving as the ecological foundation in this dark subsurface environment, providing new organic matter that sustains a microbial ecosystem beneath the West Antarctic Ice Sheet.Item Solute sources and geochemical processes in Subglacial Lake Whillans, West Antarctica(2016-05) Michaud, Alexander B.; Skidmore, Mark L.; Mitchell, Andrew C.; Vick-Majors, Trista J.Subglacial Lake Whillans (SLW), West Antarctica, is an active component of the subglacial hydrological network located beneath 800 m of ice. The fill and drain behavior of SLW leads to long (years to decades) water residence times relative to those in mountain glacier systems. Here, we present the aqueous geochemistry of the SLW water column and pore waters from a 38-cm-long sediment core. Stable isotopes indicate that the water is primarily sourced from basal-ice melt with a minor contribution from seawater that reaches a maximum of ∼6% in pore water at the bottom of the sediment core. Silicate weathering products dominate the crustal (non-seawater) component of lake- and pore-water solutes, and there is evidence for cation exchange processes within the clay-rich lake sediments. The crustal solute component ranges from 6 meq L–1 in lake waters to 17 meq L–1 in the deepest pore waters. The pore-water profiles of the major dissolved ions indicate a more concentrated solute source at depth (>38 cm). The combination of significant seawater and crustal components to SLW lake and sediment pore waters in concert with ion exchange processes result in a weathering regime that contrasts with other subglacial systems. The results also indicate cycling of marine water sourced from the sediments back to the ocean during lake drainage events.Item From dinosaurs to birds: a tail of evolution(2014-05) Rashid, Dana J.; Chapman, Susan C.; Larsson, Hans C. E.; Organ, Chris L.; Merzdorf, Christa; Bradley, Roger S.; Horner, John R.A particularly critical event in avian evolution was the transition from long- to short-tailed birds. Primitive bird tails underwent significant alteration, most notably reduction of the number of caudal vertebrae and fusion of the distal caudal vertebrae into an ossified pygostyle. These changes, among others, occurred over a very short evolutionary interval, which brings into focus the underlying mechanisms behind those changes. Despite the wealth of studies delving into avian evolution, virtually nothing is understood about the genetic and developmental events responsible for the emergence of short, fused tails. In this review, we summarize the current understanding of the signaling pathways and morphological events that contribute to tail extension and termination and examine how mutations affecting the genes that control these pathways might influence the evolution of the avian tail. To generate a list of candidate genes that may have been modulated in the transition to short-tailed birds, we analyzed a comprehensive set of mouse mutants. Interestingly, a prevalent pleiotropic effect of mutations that cause fused caudal vertebral bodies (as in the pygostyles of birds) is tail truncation. We identified 23 mutations in this class, and these were primarily restricted to genes involved in axial extension. At least half of the mutations that cause short, fused tails lie in the Notch/Wnt pathway of somite boundary formation or differentiation, leading to changes in somite number or size. Several of the mutations also cause additional bone fusions in the trunk skeleton, reminiscent of those observed in primitive and modern birds. All of our findings were correlated to the fossil record. An open question is whether the relatively sudden appearance of short-tailed birds in the fossil record could be accounted for, at least in part, by the pleiotropic effects generated by a relatively small number of mutational events.Item Chemolithotrophic primary production in a subglacial ecosystem(2014-10) Boyd, Eric S.; Hamilton, Trinity L.; Havig, Jeff R.; Skidmore, Mark L.; Shock, Everett L.Glacial comminution of bedrock generates fresh mineral surfaces capable of sustaining chemotrophic microbial communities under the dark conditions that pervade subglacial habitats. Geochemical and isotopic evidence suggests that pyrite oxidation is a dominant weathering process generating protons that drive mineral dissolution in many subglacial systems. Here, we provide evidence correlating pyrite oxidation with chemosynthetic primary productivity and carbonate dissolution in subglacial sediments sampled from Robertson Glacier (RG), Alberta, Canada. Quantification and sequencing of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) transcripts suggest that populations closely affiliated with Sideroxydans lithotrophicus, an iron sulfide-oxidizing autotrophic bacterium, are abundant constituents of microbial communities at RG. Microcosm experiments indicate sulfate production during biological assimilation of radiolabeled bicarbonate. Geochemical analyses of subglacial meltwater indicate that increases in sulfate levels are associated with increased calcite and dolomite dissolution. Collectively, these data suggest a role for biological pyrite oxidation in driving primary productivity and mineral dissolution in a subglacial environment and provide the first rate estimate for bicarbonate assimilation in these ecosystems. Evidence for lithotrophic primary production in this contemporary subglacial environment provides a plausible mechanism to explain how subglacial communities could be sustained in near-isolation from the atmosphere during glacial-interglacial cycles.