The contribution of carbon and water in modulating wood formation in black spruce saplings

Nonstructural carbohydrates (NSCs) play a crucial role in xylem formation and represent, with water, the main constraint to plant growth. We assessed the relationships between xylogenesis and NSCs in order to (1) verify the variance explained by NSCs and (2) determine the influence of intrinsic (tissue supplying carbon) and extrinsic (water availability and temperature) factors. During 2 years, wood formation was monitored in saplings of black spruce (Picea mariana) subjected to a dry period of about 1 month in June and exposed to different temperature treatments in a greenhouse. In parallel, NSC concentrations were determined by extracting the sugar compounds from two tissues (cambium and inner xylem), both potentially supplying carbon for wood formation. A mixed-effect model was used to assess and quantify the potential relationships. Total xylem cells, illustrating meristematic activity, were modeled as a function of water, sucrose, and D-pinitol (conditional r2 of 0.79). Water availability was ranked as the most important factor explaining total xylem cell production, while the contribution of carbon was lower. Cambium stopped dividing under water deficit, probably to limit the number of cells remaining in differentiation without an adequate amount of water. By contrast, carbon factors were ranked as most important in explaining the variation in living cells (conditional r2 of 0.49), highlighting the functional needs during xylem development, followed by the tissue supplying the NSCs (cambium) and water availability. This study precisely demonstrates the role of carbon and water in structural growth expressed as meristematic activity and tissue formation

Phosphatidylinositol 3,5-bisphosphate: A Molecular Switch of Vacuolar Fusion and Fission

Abstract Vacuoles purified from Saccharomyces cerevisiae are a well-studied model for membrane fusion and fission as the machinery is highly conserved throughout eukaryotes. Vacuole membranes undergo cycles of fusion and fission which have distinct mechanisms but are in part controlled by overlapping regulators. Both processes are dependent on proteins, ion concentrations, and lipid composition, highlighting the complex regulation of vacuole homeostasis. Previous studies have shown the lipid PI(3,5)P2 (phosphatidylinositol 3,5-bisphosphate) is a crucial activator of vacuolar fission. PI(3,5)P2 is generated by the PI3P 5-kinase Fab1 . Fab1 is activated in response to osmotic stress leading to a sharp rise in PI(3,5)P2 levels. Increases in PI(3,5)P2 activates the calcium channel Yvc1, causing calcium to efflux from the vacuole. This, along with PI(3,5)P2 activation of Vph1 (a subunit of a vacuolar V-ATPase) results in fragmentation of the vacuole. Here we show that PI(3,5)P2 is a novel inhibitor of vacuolar fusion. Additionally we found PI(3,5)P2 does not prevent fusion by inhibiting priming and trans-SNARE pairing (the early steps of fusion). In order to look at the later steps of fusion, we conducted lipid mixing experiments to measure it’s effects on hemi-fusion, the precursor step to vacuolar fusion. Our results show that PI(3,5)P2 inhibits hemi-fusion, but the exact mechanism is still unclear. We also hypothesized that PI(3,5)P2 acts to inhibit fusion through either the Yvc1 calcium efflux or the Vph1 V-ATPase pathway. Vph1 interactions promote either vacuolar fusion or fission depending on binding partners. We predicted PI(3,5)P2 to disrupt Vph1 fusion complexes while promoting fission complexes. But, experiments using TAP-tagged Vph1 were inconclusive. Also, experiments with Yvc1 knockout yeast retained sensitivity to PI(3,5)P2 - interestingly, the calcium influx pump Pmc1 was found to be enhanced by PI(3,5)P2, which may explain decreased calcium influx.Ope

Research collaboration between China and Denmark for development of systemic approaches to agro-ecological pest management without pesticides with focus on vegetable, fruit and berry crops. Proceedings and recommendations from two network workshops

This report is the result of a network project which was established to discuss the potential for collaboration on development of systemic approaches to pest management without pesticides between Chinese and Danish researchers. The focus is on systemic approaches rather than input substitution of synthetic chemicals with agents of natural origin, however, the latter is considered as an integrated tool for the development and design of systemic approaches. The discussions were, furthermore, limited to management of invertebrate pests as well as diseases, while other pests such as weeds have not been included in the discussions. The discussions took place at two workshops and were based on presentations of research from the two countries and field visits in China and Denmark. After the first workshop that took place in China, it was agreed that Chinese and Danish researchers in this particular field had mutual interests and priorities and that there was a potential for creating collaboration that could yield results beneficial for the agricultural/horticultural sectors in both countries. It was also agreed that in spite of the many differences between variation in climate and ecosystems, as well as in farming systems and their organization in China and Denmark, there were many similarities in the production of high-value crops in the two countries, such as vegetables, fruit and berries and, therefore, an obvious focus for joint research efforts. It was also agreed that joint research efforts could aim at specific crops as well as aiming at the development of specific research approaches. Based on the observations and the agreements of the first workshop, the second workshop, which took place in Denmark, focused more specifically on the development of a research framework with specified research questions/topics. Two groups were formed – one working with vegetables and one with fruit and berries working in parallel – both looking into what kind of research is needed for development of systemic approaches to pesticide-free pest management should include both well-known practices and new practices. Although the discussions in the two groups took separate routes and unfolded and described the research topics in each their way, there was a clear consistency between the outputs of the work of the two groups. Each had identified three main research themes that more or less followed the same line and has been merged into three specific recommendations on themes for collaboration, namely: 1) ‘Research to provide the biological foundation and understanding of mechanisms and interactions for development of non-chemical solutions and to improve efficiency of new and existing control methods for severe pest problems’. 2) Research in ‘How best to integrate multifunctional plants (and crops) and use diversification to create a more healthy and productive farming system which is resilient to pests?’ 3) Research in ‘How to design and integrate pest management in eco-functional cropping systems at field and farm/landscape level?

Two low-power optical data transmission ASICs for the ATLAS Liquid Argon Calorimeter readout upgrade

A serializer ASIC and a VCSEL driver ASIC are needed for the front-end optical data transmission in the ATLAS liquid argon calorimeter readout phase-I upgrade. The baseline ASICs are the serializer LOCx2 and the VCSEL driver LOCld, designed in a 0.25-{\mu}m Silicon-on-Sapphire (SoS) CMOS technology and consumed 843 mW and 320 mW, respectively. Based on a 130-nm CMOS technology, we design two pin-to-pin-compatible backup ASICs, LOCx2-130 and LOCld-130. Their power consumptions are much lower then of their counterparts, whereas other performance, such as the latency, data rate, and radiation tolerance, meet the phase-I upgrade requirements. We present the design of LOCx2-130 and LOCld-130. The test results of LOCx2-130 are also presented.Comment: 12 pages, 12 figure

Calibrating phenoCam data with phenological observations of a black spruce stand

Bud and leaf development are important phenological events and help in defining the growing period of trees. Canopy greenness derived from PhenoCam has been used to investigate leaf phenology. Questions remain on how much the continuous records of canopy greenness represent bud developmental phases, and how growing period boundaries are related to canopy greenness and bud phenology. In this study, we compared bud phenology of black spruce [Picea mariana (Mill.) B.S.P] during 2015, 2017 and 2018 with the canopy greenness, represented by Green Chromatic Coordinate (GCC), derived from PhenoCam images of a boreal stand in Quebec, Canada. Logit models were applied to estimate the probability of observing sequential phenological phases of bud burst and bud set along with GCC. GCC showed a bell-shaped pattern, with a slow increase in spring, a peak in summer and a gradual decrease in autumn. The start and end of budburst, and bud set, occurred when GCC reached 72% and 92% (spring), and 94% (autumn) of its maximum amplitude, respectively. These GCC values are reliable thresholds indicating the growing period boundaries. Our study builds a bridge between phenological observations and automatic near-surface remote sensing, providing a statistically sound protocol for calibrating PhenoCam with field observations

An NCN-pincer ligand dysprosium single-ion magnet showing magnetic relaxation via the second excited state

Single-molecule magnets are compounds that exhibit magnetic bistability purely of molecular origin. The control of anisotropy and suppression of quantum tunneling to obtain a comprehensive picture of the relaxation pathway manifold, is of utmost importance with the ultimate goal of slowing the relaxation dynamics within single-molecule magnets to facilitate their potential applications. Combined ab initio calculations and detailed magnetization dynamics studies reveal the unprecedented relaxation mediated via the second excited state within a new DyNCN system comprising a valence-localized carbon coordinated to a single dysprosium(III) ion. The essentially C(2v) symmetry of the Dy(III) ion results in a new relaxation mechanism, hitherto unknown for mononuclear Dy(III) complexes, opening new perspectives for means of enhancing the anisotropy contribution to the spin-relaxation barrier

Remarkable nucleation and growth of ultrafine particles from vehicular exhaust

High levels of ultrafine particles (UFPs; diameter of less than 50 nm) are frequently produced from new particle formation under urban conditions, with profound implications on human health, weather, and climate. However, the fundamental mechanisms of new particle formation remain elusive, and few experimental studies have realistically replicated the relevant atmospheric conditions. Previous experimental studies simulated oxidation of one compound or a mixture of a few compounds, and extrapolation of the laboratory results to chemically complex air was uncertain. Here, we show striking formation of UFPs in urban air from combining ambient and chamber measurements. By capturing the ambient conditions (i.e., temperature, relative humidity, sunlight, and the types and abundances of chemical species), we elucidate the roles of existing particles, photochemistry, and synergy of multipollutants in new particle formation. Aerosol nucleation in urban air is limited by existing particles but negligibly by nitrogen oxides. Photooxidation of vehicular exhaust yields abundant precursors, and organics, rather than sulfuric acid or base species, dominate formation of UFPs under urban conditions. Recognition of this source of UFPs is essential to assessing their impacts and developing mitigation policies. Our results imply that reduction of primary particles or removal of existing particles without simultaneously limiting organics from automobile emissions is ineffective and can even exacerbate this problem