Root Phenolic Carbon Chemistry from Genetically Modified Poplars

Biofuels are plant-derived fuel sources, and are being developed as renewable energy to meet increasing global energy demand. Some biofuels use genetically modified plants with altered lignin chemistry to be less of a barrier for the extraction of cellulose. The lignin structure of stems and leaves of genetically modified organisms (GMO’s) are known, however, root structure is often not characterized. Plant roots are thought to be the main contributor of carbon to soils during degradation and therefore the chemical composition of roots have a large control on the chemistry of soil organic matter. The potential impact of biofuel GMO’s on root chemistry is an unexplored impact of GMO biofuels application. Using carbon-13 labelled tetramethylammonium hydroxide (13C-TMAH) pyrolysis and gas chromatography-mass spectrometry (GC-MS), the chemical structure of lignin in roots can be analyzed and determined. Root tissue from field-isolated hybrid poplar plants (species with genus Populus) that were genetically modified to vary the proportion of lignin structural components were sampled to assess if known variations in stem lignin chemistry reflects in fine root (\u3c1mm ) tissue. Looking at known guaiacyl derivative compounds, a large variation in percent dihydroxyl composition of original compounds was shown, as opposed to the small variation in known syringyl derivatives. It was also found that percent composition of syringyl, guaiacyl, and cinnamyl compounds varied in each set of samples, suggesting that genetic modifications targeting stem/wood tissue significantly influence root chemistry and probably structure. This has potential implications for root decomposition, soil chemistry, nutrient uptake, and water storage

Belowground competition among invading detritivores

Author Posting. © Ecological Society of America, 2016. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecology 97 (2016): 160–170, doi:10.1890/15-0551.1.The factors regulating soil animal communities are poorly understood. Current theory favors niche complementarity and facilitation over competition as the primary forms of non-trophic interspecific interaction in soil fauna; however, competition has frequently been suggested as an important community-structuring factor in earthworms, ecosystem engineers that influence belowground processes. To date, direct evidence of competition in earthworms is lacking due to the difficulty inherent in identifying a limiting resource for saprophagous animals. In the present study, we offer the first direct evidence of interspecific competition for food in this dominant soil detritivore group by combining field observations with laboratory mesocosm experiments using 13C and 15N double-enriched leaf litter to track consumption patterns. In our experiments, the Asian invasive species Amynthas hilgendorfi was a dominant competitor for leaf litter against two European species currently invading the temperate deciduous forests in North America. This competitive advantage may account for recent invasion success of A. hilgendorfi in forests with established populations of European species, and we hypothesize that specific phenological differences play an important role in determining the outcome of the belowground competition. In contrast, Eisenoides lonnbergi, a common native species in the Eastern United States, occupied a unique trophic position with limited interactions with other species, which may contribute to its persistence in habitats dominated by invasive species. Furthermore, our results supported neither the hypothesis that facilitation occurs between species of different functional groups nor the hypothesis that species in the same group exhibit functional equivalency in C and N translocation in the soil. We propose that species identity is a more powerful approach to understand earthworm invasion and its impacts on belowground processes.EPS Field Funds; National Science Foundation Grant Numbers: EEC-0540832, ACI 1244820, EAR-0748574; Microsoft Researc

Quantifying Four Decades of Arid-region Agricultural Development in Arequipa, Peru Using Landsat

The Arequipa Nexus Institute for Food, Energy and the Environment (Nexus Institute) is located in Southwestern Peru, generally bounded by the city of Arequipa to the east, the Majes River to the west, the Pacific Ocean to the south, and the Andes mountains to the north. Though agriculture has been practiced in parts of this cool desert region (MAT~15°C, MA

Sustainable Environment: Nexus project

Arequipa region is locaed in Southwestern Peru. The Arequipa Nexus Institute for food, energy, water and the environment aims to address the key challenges to a sustainable furture for the people in the region. This roundtable discusses about the sustainable water management, geosaptial analysis and environment sharing, long range sensor network solution for soil health monitoring and data management and sharing in this Nexus project

Immunologic and gene expression profiles of spontaneous canine oligodendrogliomas

Malignant glioma (MG), the most common primary brain tumor in adults, is extremely aggressive and uniformly fatal. Several treatment strategies have shown significant preclinical promise in murine models of glioma; however, none have produced meaningful clinical responses in human patients. We hypothesize that introduction of an additional preclinical animal model better approximating the complexity of human MG, particularly in interactions with host immune responses, will bridge the existing gap between these two stages of testing. Here, we characterize the immunologic landscape and gene expression profiles of spontaneous canine glioma and evaluate its potential for serving as such a translational model. RNA in situ hybridization, flowcytometry, and RNA sequencing were used to evaluate immune cell presence and gene expression in healthy and glioma-bearing canines. Similar to human MGs, canine gliomas demonstrated increased intratumoral immune cell infiltration (CD4+, CD8+ and CD4+Foxp3+ T cells). The peripheral blood of glioma-bearing dogs also contained a relatively greater proportion of CD4+Foxp3+ regulatory T cells and plasmacytoid dendritic cells. Tumors were strongly positive for PD-L1 expression and glioma-bearing animals also possessed a greater proportion of immune cells expressing the immune checkpoint receptors CTLA-4 and PD-1. Analysis of differentially expressed genes in our canine populations revealed several genetic changes paralleling those known to occur in human disease. Naturally occurring canine glioma has many characteristics closely resembling human disease, particularly with respect to genetic dysregulation and host immune responses to tumors, supporting its use as a translational model in the preclinical testing of prospective anti-glioma therapies proven successful in murine studies

Rapid analysis of 13C in plant-wax n-alkanes for reconstruction of terrestrial vegetation signals from aquatic sediments

Author Posting. © American Geophysical Union, 2004. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 5 (2004): Q10004, doi:10.1029/2004GC000772.Long-chain, odd-carbon-numbered C25 to C35 n-alkanes are characteristic components of epicuticular waxes produced by terrestrial higher plants. They are delivered to aquatic systems via eolian and fluvial transport and are preserved in underlying sediments. The isotopic compositions of these products can serve as records of past vegetation. We have developed a rapid method for stable carbon isotopic analyses of total plant-wax n-alkanes using a novel, moving-wire system coupled to an isotope-ratio mass spectrometer (MW-irMS). The n-alkane fractions are prepared from sediment samples by (1) saponification and extraction with organic solvents, (2) chromatographic separation using silica gel, (3) isolation of straight-chain carbon skeletons using a zeolite molecular sieve, and (4) oxidation and removal of unsaturated hydrocarbons with RuO4. Short-chain n-alkanes of nonvascular plant origin (<C25) are removed by evaporation on the moving wire. Test samples processed using this procedure yielded n-alkane fractions essentially free of interfering components. The δ13C values obtained by MW-irMS did not differ significantly from weighted averages of individual n-alkane δ13C values obtained by irmGC-MS. Isotopic variations in compound-class n-alkane fractions from a latitudinal transect of core-top sediments from the Southwest African margin (3°N–28°S) were congruent with those measured by compound-specific isotopic analyses of plant-wax n-alkanes. The amplitude of the variations was smaller, indicating contributions from non-plant-wax hydrocarbons, but the measurements revealed variations in carbon isotopic composition that are consistent with vegetation zones on the adjacent continent.We thank the WHOI Summer Student Fellow program and NSF (BCS-0218511) for funding

Seasonal differences in trace metal concentrations in the major rivers of the hyper-arid southwestern Andes basins of Peru

The southern rivers of Peru originate in the Andes Mountains and flow in a southwestern direction to the Pacific Ocean through one of the most hyper-arid regions of the world. During each sub-equatorial summer from December to February, rains and snow melt in the Andes increase the streamflow in these rivers, even as they pass through the 100 km arid zone to the ocean. This study quantified seasonal dynamics of 34 trace metal elements (TM) and other constituent concentrations in four southern river basins of Peru (Chili-Quilca, Tambo, Camana-Majes-Colca, and Ocoña) during 2019–2020. Consistent with previous studies, we observed that: (1) the river water in the southern basins had relatively high concentrations of B, As, Fe, Al, Mn, P, Pb and Ni, with As the most ubiquitous toxic TM in all the basins, often detected at concentrations surpassing Peruvian and USEPA regulated concentrations; and (2) basins with the most to least toxic TM contamination were the Tambo > Chili-Quilca > Camana-Majes-Colca > Ocoña. Seasonal streamflow strongly influenced the concentrations of twenty TM, with 15 TM (Al, Au, Ba, Cd, Co, Cu, Fe, Gd, Mn, Ni, P, Pb, Ti, Yb and Zr) consistently higher in the wet season, and with As, B, Ge, Li, and Pd higher in the dry season. Our results improve the understanding of seasonal variability and vulnerability in western Andes superficial water sources, which are highly influenced by both local geogenic and anthropogenic conditions. A Spanish translation of this paper is available in the online Supplementary Material

A 13C NMR study of decomposing logging residues in an Australian hoop pine plantation

Purpose Residue retention is important for nutrient and water economy in subtropical plantation forests. We examined decomposing hoop pine (Araucaria cunninghamii Ait. Ex D. Don) residues-foliage, branches, and stem wood-to determine the changes in structural chemistry that occur during decomposition. Materials and methods Residues were incubated in situ using 0.05 m2 microplots. We used solid-state 13C nuclear magnetic resonance (NMR) spectroscopy to determine the structural composition of harvest residues in the first 24 months of decomposition. Results and discussion The spectral data for branch and stem residues were generally similar to one another and showed few changes during decomposition. The lignin content of branch and foliage residues decreased during decomposition. When residues were mixed together during decomposition, the O-alkyl fraction of foliage decreased initially then increased up to 24 months, while the alkyl carbon (C) fraction exhibited the opposite pattern. The decomposition of woody hoop pine residues (branch and stem wood) is surprisingly uniform across the major C forms elucidated with 13C NMR, with little evidence of preferential decomposition. When mixed with branch and stem materials, foliage residues showed significant short- and long-term compositional changes. This synergistic effect may be due to the C/N ratio of the treatments and the structure of the microbial decomposer community. Conclusions Twenty-four months of decomposition of hoop pine residues did not result in substantial accumulation of recalcitrant C forms, suggesting that they may not contribute to long-term C sequestration.No Full Tex