Search

A field experiment was conducted in 2017 and 2018 to investigate the responses of fine root growth and morphology plasticity to drip irrigation and nitrogen fertigation (DIF) in a young triploid P. tomentosa plantation in the North China Plain. We monitored four DIF treatments (I20F0, I20FH, I45F0, I45FH), which were the combinations of two irrigation thresholds (− 20 kPa and − 45 kPa, denoted as I20 and I45) and two N fertigation amounts (0, denoted as F0; 220 and 260 kg N ha−1 year−1 in 2017 and 2018, denoted as FH). Some soil properties and aboveground growth parameters were also monitored. I20 significantly improved fine root biomass density (FRBD) by 156.92% and induced a significant reduction of specific root length (SRL) by 28.79% in 0–30 cm soil layers than I45, and FH significantly decreased fine root length density (− 62.88%), surface area (− 54.01%), and SRL (− 39.01%) in 30–80 cm soil layers than F0 in 2017. Fine root traits differed little among DIF treatments in 0–30 cm soil layers in 2018, but I20 significantly improved FRBD by 259.98% than I45 and FH significantly improved fine root averaged diameter by 67.14% in 30–80 cm soil layers than F0. These suggested that fine root had a conservative foraging strategy in water- and nitrogen-rich conditions. All the trait plasticity might be due to the changeable soil properties (i.e. soil water content, organic matter, nitrate and ammonium nitrogen, and total phosphorus). Based on the little difference of fine root mass among DIF treatments in two years, we hold the view that fine root distribution pattern and some growth and morphological traits adapted to water-nitrogen heterogeneity more easily than the mass plasticity in young aged P. tomentosa plantations. Yet enhancing our understanding of fine root foraging strategy in response to DIF practices and how it affects tree growth requires more attention to some physiological and biochemical processes and the growth dynamics of the root systems. • Fine root had a conservative foraging strategy in resource-rich conditions. • Key indices affecting fine root trait plasticity were SWC, OM, NO 3- -N, NH 4+ -N, and TP. • Fine root showed higher trait plasticity compared with mass plasticity under DIF practices. [ABSTRACT FROM AUTHOR]

Abstract: Chronic pain associated with osteoarthritis (OA) remains an intractable problem with few effective treatment options. New approaches are needed to model the disease biology and to drive discovery of therapeutics. We present an in vitro model of OA pain, where dorsal root ganglion (DRG) sensory neurons were sensitized by a defined mixture of disease-relevant inflammatory mediators, here called Sensitizing PAin Reagent Composition or SPARC. Osteoarthritis-SPARC components showed synergistic or additive effects when applied in combination and induced pain phenotypes in vivo. To measure the effect of OA-SPARC on neural firing in a scalable format, we used a custom system for high throughput all-optical electrophysiology. This system enabled light-based membrane voltage recordings from hundreds of neurons in parallel with single cell and single action potential resolution and a throughput of up to 500,000 neurons per day. A computational framework was developed to construct a multiparameter OA-SPARC neuronal phenotype and to quantitatively assess phenotype reversal by candidate pharmacology. We screened ∼3000 approved drugs and mechanistically focused compounds, yielding data from over 1.2 million individual neurons with detailed assessment of functional OA-SPARC phenotype rescue and orthogonal "off-target" effects. Analysis of confirmed hits revealed diverse potential analgesic mechanisms including ion channel modulators and other mechanisms including MEK inhibitors and tyrosine kinase modulators. Our results suggest that the Raf-MEK-ERK axis in DRG neurons may integrate the inputs from multiple upstream inflammatory mediators found in osteoarthritis patient joints, and MAPK pathway activation in DRG neurons may contribute to chronic pain in patients with osteoarthritis., (Copyright © 2023 International Association for the Study of Pain.)