Above- and Belowground Development of a Fast-Growing Willow Planted in Acid-Generating Mine Technosol

Surface metal mining produces large volumes of waste rocks. If they contain sulfide minerals, these rocks can generate a flow of acidic water from the mining site, known as acid mine drainage (AMD), which increases trace metals availability for plant roots. Adequate root development is crucial to decreasing planting stress and improving phytoremediation with woody species. However, techniques to improve revegetation success rarely take into account root development. An experiment was conducted at a gold mine in Quebec, Canada, to evaluate the establishment ability over 3 yr of a fast-growing willow (Salix miyabeana Sx64) planted in acid-generating waste rocks. The main objective was to study root development in the soil profile and trace element accumulation in leaves among substrates varying in thickness (0, 20, and 40 cm of soil) and composition (organic carbon [OC] and alkaline AMD treatment sludge). Trees directly planted in waste rocks survived well (69%) but had the lowest productivity (lowest growth in height and diameter, aerial biomass, total leaf area, and root-system size). By contrast, the treatment richer in OC showed the greatest aerial biomass and total leaf area the first year; the thicker treatment resulted in the greatest growth in height and diameter, aboveground biomass, and root-system size in both the first and third years. Willow root development was restricted to soil layers during the first year, but this restriction was overcome in the third year after planting. Willow accumulation factors in leaves were below one for all investigated trace metals except for zinc (Zn), cadmium (Cd), and strontium. For Cd and Zn, concentrations increased with time in willow foliage, decreasing the potential of this willow species use for phytostabilization, despite its ability to rapidly develop extensive root systems in the mine Technosol

Fast-growing willow development on acidic mining wastes for rapid greening purposes

Metal mining generates large volumes of wastes, which can contain sulphide minerals that generate acid when exposed to atmospheric conditions, providing unfavourable conditions for plant establishment. In particular, mining waste rocks are piled on tens of meters, and remain devoid of vegetation, creating a desolated anthropogenic landscape. The use of adapted plants able to grow quickly on waste rocks can help increasing their aesthetical aspect. An experiment was conducted at the Westwood mine in Quebec to evaluate the establishment ability of a fast-growing willow (Salix miyabeana Sx64) on acid- generating waste rocks. The main objective was to identify substrate thickness and composition that maximized willow productivity while limiting water stress exposure and trace metal accumulation. A randomized complete block design was established in June 2014 with five treatments: (1) direct planting in waste rocks, (2) and (3) 20 cm or 40 cm moraine amended with 20% of organic matter (OM) (in volume), (4) 20 cm moraine at 40% of OM, and (5) 20 cm moraine at 20% of OM over 20 cm lime sludge from water treatment. Trees directly planted in waste rocks survived well (75%) but had the lowest aerial productivity, with the lowest height and diameter growth, aerial biomass, and total leaf area, while the treatment richer in OM showed the greatest aerial biomass and total leaf area, and the thicker treatment the greatest height and diameter growth. Willow root development was restricted to cover soils the first year after planting, and foliar δ13C values decreased in thicker soil (40 cm) compared to thin soil (20 cm). Willow accumulation factors in leaves were below one for all investigated trace metals except Zn

Molecular mechanism regulating myosin and cardiac functions by ELC

The essential myosin light chain (ELC) is involved in modulation of force generation of myosin motors and cardiac contraction, while its mechanism of action remains elusive. We hypothesized that ELC could modulate myosin stiffness which subsequently determines its force production and cardiac contraction. We therefore generated heterologous transgenic mouse (TgM) strains with cardiomyocyte-specific expression of ELC with human ventricular ELC (hVLC-1; TgM(hVLC-1)) or E56G-mutated hVLC-1 (hVLC-1(E56G); TgM(E56G)). hVLC-1 or hVLC-1(E56G) expression in TgM was around 39% and 41%, respectively of total VLC-1. Laser trap and in vitro motility assays showed that stiffness and actin sliding velocity of myosin with hVLC-1 prepared from TgM(hVLC-1) (1.67pN/nm and 2.3{my}m/s, respectively) were significantly higher than myosin with hVLC-1(E56G) prepared from TgM(E56G) (1.25pN/nm and 1.7{my}m/s, respectively) or myosin with mouse VLC-1 (mVLC-1) prepared from C57/BL6 (1.41 pN/nm and 1.5+-0.03 {my}m/s, respectively). Maximal left ventricular pressure development of isolated perfused hearts in vitro prepared from TgM(hVLC-1) (80.0mmHg) were significantly higher than hearts from TgM(E56G) (66.2mmHg) or C57/BL6 (59.3+-3.9 mmHg). These findings show that ELCs decreased myosin stiffness, in vitro motility, and thereby cardiac functions in the order hVLC-1 > hVLC-1(E56G) ≈ mVLC-1. They also suggest a molecular pathomechanism of cardiomyopathies caused by hVLC-1 mutations

Individual tree and stand-level carbon and nutrient contents across one rotation of loblolly pine plantations on a reclaimed surface mine

While reclaimed loblolly pine (Pinus taeda L.) plantations in east Texas, USA have demonstrated similar aboveground productivity levels relative to unmined forests, there is interest in assessing carbon (C) and nutrients in aboveground components of reclaimed trees. Numerous studies have previously documented aboveground biomass, C, and nutrient contents in loblolly pine plantations; however, similar data have not been collected on mined lands. We investigated C, N, P, K, Ca, and Mg aboveground contents for first-rotation loblolly pine growing on reclaimed mined lands in the Gulf Coastal Plain over a 32-year chronosequence and correlated elemental rates to stand age, stem growth, and similar data for unmined lands. At the individual tree level, we evaluated elemental contents in aboveground biomass components using tree size, age, and site index as predictor variables. At the stand-level, we then scaled individual tree C and nutrients and fit a model to determine the sensitivity of aboveground elemental contents to stand age and site index. Our data suggest that aboveground C and nutrients in loblolly pine on mined lands exceed or follow similar trends to data for unmined pine plantations derived from the literature. Diameter and height were the best predictors of individual tree stem C and nutrient contents (R ≥ 0.9473 and 0.9280, respectively) followed by stand age (R ≥ 0.8660). Foliage produced weaker relationships across all predictor variables compared to stem, though still significant (P ≤ 0.05). The model for estimating stand-level C and nutrients using stand age provided a good fit, indicating that contents aggrade over time predictably. Results of this study show successful modelling of reclaimed loblolly pine aboveground C and nutrients, and suggest elemental cycling is comparable to unmined lands, thus providing applicability of our model to related systems

Le revenu cadastral et les charges de l'agriculture

Larchevêque M. Le revenu cadastral et les charges de l'agriculture. In: Économie rurale. N°23, 1955. pp. 39-42

Étude théorique de la régiosélectivité de l'ouverture des esters glycidiques par les organométalliques

Afin de contribuer à l'interprétation de la régiosélectivité de l'ouverture par les organométalliques des époxydes fonctionnalisés, nous avons étudié théoriquement la structure géométrique, la répartition des charges et la localisation des orbitales moléculaires du glycidate de méthyle non substitué ou substitué par un méthyle en C3 (configuration trans ou cis) et des complexes correspondants avec le cation lithium. Les calculs de type ab initio ont été effectués au niveau SCF avec une base minimale puis des bases étendues. Des trois facteurs possibles — électrostatique, stérique et de symétrie — seul le facteur stérique semble pouvoir expliquer la régiosélectivité de l'ouverture de ces composés par les cuprates lithiens

Compost effect on bacterial and fungal colonization of kermes oak leaf litter in a terrestrial Mediterranean ecosystem

International audienceMediterranean soils are generally low in organic matter and have a low water holding capacity. Moreover, recurrent fires are common in Mediterranean regions and increase the deterioration of these soils. Soil properties and ecosystem resilience after fire could be improved by amendment with compost, which is a source of organic matter and nutrients. A way to determine ecosystem integrity is to study leaf litter breakdown, which is a vital process in the functioning of terrestrial ecosystems and involves fungi and bacteria. In this study, we determined fungal and bacterial biomass associated with decomposing oak leaves (Quercus coccifera L.) in a burnt shrub amended ecosystem during 1.5 years. Three treatments were studied: control, 50 t ha À1 and 100 t ha À1 of co-composted sewage sludge and green wastes. Bacterial biomass was not affected, although moisture, N and P concentrations in litter were increased by the amendment. However, fungal biomass was depressed on plots amended with 100 t ha À1 , and negatively correlated to exchangeable P. For all treatments, both types of microorganisms followed marked seasonal dynamics, with peaks of biomass during the wet periods of the year.

Absolute configuration of eldanolide, the wing gland pheromone of the male african sugar-cane borer, Eldona saccharina (Wlk) syntheses of its (+) and (-) enantiomers

International audienc