Global Patterns and Controls of Nutrient Immobilization On Decomposing Cellulose In Riverine Ecosystems

Microbes play a critical role in plant litter decomposition and influence the fate of carbon in rivers and riparian zones. When decomposing low-nutrient plant litter, microbes acquire nitrogen (N) and phosphorus (P) from the environment (i.e., nutrient immobilization), and this process is potentially sensitive to nutrient loading and changing climate. Nonetheless, environmental controls on immobilization are poorly understood because rates are also influenced by plant litter chemistry, which is coupled to the same environmental factors. Here we used a standardized, low-nutrient organic matter substrate (cotton strips) to quantify nutrient immobilization at 100 paired stream and riparian sites representing 11 biomes worldwide. Immobilization rates varied by three orders of magnitude, were greater in rivers than riparian zones, and were strongly correlated to decomposition rates. In rivers, P immobilization rates were controlled by surface water phosphate concentrations, but N immobilization rates were not related to inorganic N. The N:P of immobilized nutrients was tightly constrained to a molar ratio of 10:1 despite wide variation in surface water N:P. Immobilization rates were temperature-dependent in riparian zones but not related to temperature in rivers. However, in rivers nutrient supply ultimately controlled whether microbes could achieve the maximum expected decomposition rate at a given temperature

Effects of exotic riparian vegetation on leaf breakdown by shredders: a tropical-temperate comparison

Displacement of riparian vegetation by exotic species is a global phenomenon with the potential to affect leaf breakdown rates by shredders. We predicted that exotic riparian vegetation would have a greater effect on leaf breakdown by temperate than by tropical shredders because temperate shredders usually feed on a limited range of generally palatable leaves, whereas tropical shredders are naturally exposed to a higher variety of leaves, many of them unpalatable. We tested 3 hypotheses with common shredder assemblages from tropical Queensland and temperate Tasmania (Australia): 1) tropical shredders are equally efficient at breaking down native and exotic vegetation, whereas temperate shredders are less efficient at breaking down exotic vegetation; 2) tropical shredders are more generalist in their leaf choices than temperate shredders; and 3) shredders are more generalist in their leaf choices among exotic than among native vegetation. Hypothesis 1 was not supported. Caddisflies (tropical or temperate) were able to consume both native and exotic leaves, whereas non-caddisfly shredders fed only on native leaves, a result suggesting that shredding capacity depends on the identity of the shredder species or their phylogenetic position rather than on their origin. Hypothesis 2 was supported. Tropical shredders fed on various leaf types, whereas most temperate shredders chose one leaf type and fed on it for the duration of the experiment. Hypothesis 3 was not supported. Specificity of shredder choices did not differ between native and exotic leaves, a result suggesting that shredding behavior is not flexible, regardless of the leaf litter available. Thus, invasive riparian plants may affect leaf breakdown by shredders, particularly in temperate streams, but effects may vary depending on assemblage composition, the nature and timing of litterfall, and interactions with climate.Peer Reviewe

Networking for advanced molecular diagnosis in acute myeloid leukemia patients is possible: the PETHEMA NGS-AML project

Next-Generation Sequencing has recently been introduced to efficiently and simultaneously detect genetic variations in acute myeloid leukemia. However, its implementation in the clinical routine raises new challenges focused on the diversity of assays and variant reporting criteria. To overcome this challenge, the PETHEMA group established a nationwide network of reference laboratories aimed to deliver molecular results in the clinics. We report the technical cross-validation results for next-generation sequencing panel genes during the standardization process and the clinical validation in 823 samples of 751 patients with newly diagnosed or refractory/relapse acute myeloid leukemia. Two cross-validation rounds were performed in seven nationwide reference laboratories in order to reach a consensus regarding quality metrics criteria and variant reporting. In the pre-standardization cross-validation round, an overall concordance of 60.98% was obtained with a great variability in selected genes and conditions across laboratories. After consensus of relevant genes and optimization of quality parameters the overall concordance rose to 85.57% in the second cross-validation round. We show that a diagnostic network with harmonized next-generation sequencing analysis and reporting in seven experienced laboratories is feasible in the context of a scientific group

Characteristics and outcomes of adult patients in the PETHEMA registry with relapsed or refractory FLT3-ITD mutation-positive acute myeloid leukemia

Simple Summary Most adult patients with acute myeloid leukemia (AML) relapse after achieving complete remission with chemotherapy; however, there is no standard second-line (salvage) treatment. We retrospectively investigated 404 patients aged >= 18 years with relapsed/refractory (R/R) AML with an FMS-like tyrosine kinase 3 (FLT3) mutation, treated at a PETHEMA (NCT02607059) site between 1998 and 2018. Patients received salvage treatment with intensive therapy (n = 261), non-intensive therapy (n = 63) or supportive care (n = 80). Complete remission was achieved by 48% of patients who received intensive therapy vs. 19% with non-intensive therapy. Intensive/non-intensive therapy prolonged overall survival significantly compared with supportive therapy. Of evaluable patients, 22% received an allogeneic stem-cell transplant after complete remission. The majority of patients with FLT3-mutated R/R AML received intensive salvage therapy, with the best outcomes being obtained when intensive salvage treatment was combined with stem-cell transplant. This retrospective study investigated outcomes of 404 patients with relapsed/refractory (R/R) FMS-like tyrosine kinase 3 (FLT3)-internal tandem duplication (ITD) acute myeloid leukemia (AML) enrolled in the PETHEMA registry, pre-approval of tyrosine kinase inhibitors. Most patients (63%) had received first-line intensive therapy with 3 + 7. Subsequently, patients received salvage with intensive therapy (n = 261), non-intensive therapy (n = 63) or supportive care only (n = 80). Active salvage therapy (i.e., intensive or non-intensive therapy) resulted in a complete remission (CR) or CR without hematological recovery (CRi) rate of 42%. More patients achieved a CR/CRi with intensive (48%) compared with non-intensive (19%) salvage therapy (p < 0.001). In the overall population, median overall survival (OS) was 5.5 months; 1- and 5-year OS rates were 25% and 7%. OS was significantly (p < 0.001) prolonged with intensive or non-intensive salvage therapy compared with supportive therapy, and in those achieving CR/CRi versus no responders. Of 280 evaluable patients, 61 (22%) had an allogeneic stem-cell transplant after they had achieved CR/CRi. In conclusion, in this large cohort study, salvage treatment approaches for patients with FLT3-ITD mutated R/R AML were heterogeneous. Median OS was poor with both non-intensive and intensive salvage therapy, with best long-term outcomes obtained in patients who achieved CR/CRi and subsequently underwent allogeneic stem-cell transplant