Carbon allocation to ectomycorrhizal fungi correlates with belowground allocation in culture studies
ECOLOGY
Authors: Hobbie, EA
Abstract
Ectomycorrhizal fungi form symbioses with most temperate and boreal tree species, but difficulties in measuring carbon allocation to these symbionts have prevented the assessment of their importance in forest ecosystems. Here, I Surveyed allocation patterns in 14 culture studies and five field studies of ectomycorrhizal plants. In Culture Studies, allocation to ectomycorrhizal fungi (NPPf) was linearly related to total below-round net primary production (NPPb) by the equation NPPf = 41.5% x NPPb - 11.3% (r(2) = 0.55, P < 0.001) and ranged from 1% to 2 1% of total net primary production. As a percentage of NPP, allocation to ectomycorrhizal fungi was highest at. lowest plant growth rates and lowest nutrient availabilities. Because total below ground allocation can be estimated using carbon balance techniques, these relationships should allow ecologists to incorporate mycorrhizal fungi into existing ecosystem models. In field Studies, allocation to ectomycorrhizal fungi ranged from 0% to 22% of total allocation, but wide differences in measurement techniques made intercomparisons difficult. Techniques such as fungal in-growth cores, root branching-order studies, and isotopic analyses Could refine Our estimates of turnover rates of fine roots, mycorrhizae, and extraradical hyphae. Together with ecosystem modeling, such techniques could soon provide good estimates of the relative importance of root vs. fungal allocation in belowground carbon budgets.
Fibroblasts from Distinct Pancreatic Pathologies Exhibit Disease-Specific Properties
CANCER RESEARCH
Authors: Barrera, Lawrence N.; Evans, Anthony; Lane, Brian; Brumskill, Sarah; Oldfield, Frances E.; Campbell, Fiona; Andrews, Timothy; Lu, Zipeng; Perez-Mancera, Pedro A.; Liloglou, Triantafillos; Ashworth, Milton; Jalali, Mehdi; Dawson, Rebecca; Nunes, Quentin; Phillips, Phoebe A.; Timms, John F.; Halloran, Christopher; Greenhalf, William; Neoptolemos, John P.; Costello, Eithne
Abstract
Although fibrotic stroma forms an integral component of pancreatic diseases, whether fibroblasts programmed by different types of pancreatic diseases are phenotypically distinct remains unknown. Here, we show that fibroblasts isolated from patients with pancreatic ductal adenocarcinoma (PDAC), chronic pancreatitis (CP), periampullary tumors, and adjacent normal (NA) tissue (N = 34) have distinct mRNA and miRNA profiles. Compared with NA fibroblasts, PDAC-associated fibroblasts were generally less sensitive to an antifibrotic stimulus (NPPB) and more responsive to positive regulators of activation such as TGF beta 1 and WNT. Of the disease-associated fibroblasts examined, PDAC- and CP-derived fibroblasts shared greatest similarity, yet PDAC-associated fibroblasts expressed higher levels of tenascin C (TNC), a finding attributable to miR-137, a novel regulator of TNC. TNC protein and transcript levels were higher in PDAC tissue versus CP tissue and were associated with greater levels of stromal activation, and conditioned media from TNC-depleted PDAC-associated fibroblasts modestly increased both PDAC cell proliferation and PDAC cell migration, indicating that stromal TNC may have inhibitory effects on PDAC cells. Finally, circulating TNC levels were higher in patients with PDAC compared with CP. Our characterization of pancreatic fibroblast programming as disease-specific has consequences for therapeutic targeting and for the manner in which fibroblasts are used in research. Significance: Primary fibroblasts derived from various types of pancreatic diseases possess and retain distinct molecular and functional characteristics in culture, providing a series of cellular models for treatment development and disease-specific research.