Biological activity and organic matter mineralization of soils amended with biowaste composts

This study aims to elucidate the significance of compost and soil characteristics for the biological activity of compost‐amended soils. Two agricultural soils (Ap horizon, loamy arable Orthic Luvisol and Ah horizon, sandy meadow Dystric Cambisol) and a humus‐free sandy mineral substrate were amended with two biowaste composts of different maturity in a controlled microcosm system for 18 months at 5 °C and 14 °C, respectively. Compost application increased the organic matter mineralization, the C_mic : C_org ratio, and the metabolic quotients significantly in all treatments. The total amount of C_org mineralized ranged from < 1 % (control plots) to 20 % (compost amended Dystric Cambisol). Incubation at 14 °C resulted in 2.7‐ to 4‐fold higher cumulative C_org mineralization compared to 5 °C. The C_mic : C_org ratios of the compost‐amended plots declined rapidly during the first 6 months and reached a similar range as the control plots at the end of the experiment. This effect may identify the compost‐derived microbial biomass as an easily degradable C source. Decreasing mineralization rates and metabolic quotients indicated a shift from a compost‐derived to a soil‐adapted microbial community. The C_org mineralization of the compost amended soils was mainly regulated by the compost maturity and the soil texture (higher activity in the sandy textured soils). The pattern of biological activity in the compost‐amended mineral substrate did not differ markedly from that of the compost‐amended agricultural soils, showing that the turnover of compost‐derived organic matter dominated the overall decay process in each soil. However, a priming effect occurring for the Dystric Cambisol indicated, that the effect of compost application may be soil specific.     

A Marine λ-Oligocarrageenan Inhibits Migratory and Invasive Ability of MDA-MB-231 Human Breast Cancer Cells through Actions on Heparanase Metabolism and MMP-14/MMP-2 Axis

Sugar-based molecules such as heparins or natural heparan sulfate polysaccharides have been developed and widely studied for controlling heparanase (HPSE) enzymatic activity, a key player in extracellular matrix remodelling during cancer pathogenesis. However, non-enzymatic functions of HPSE have also been described in tumour mechanisms. Given their versatile properties, we hypothesized that sugar-based inhibitors may interfere with enzymatic but also non-enzymatic HPSE activities. In this work, we assessed the effects of an original marine λ-carrageenan derived oligosaccharide (λ-CO) we previously described, along with those of its native counterpart and heparins, on cell viability, proliferation, migration, and invasion of MDA-MB-231 breast cancer cells but also of sh-MDA-MB-231 cells, in which the expression of HPSE was selectively downregulated. We observed no cytotoxic and no anti-proliferative effects of our compounds but surprisingly λ-CO was the most efficient to reduce cell migration and invasion compared with heparins, and in a HPSE-dependent manner. We provided evidence that λ-CO tightly controlled a HPSE/MMP-14/MMP-2 axis, leading to reduced MMP-2 activity. Altogether, this study highlights λ-CO as a potent HPSE “modulator” capable of reducing not only the enzymatic activity of HPSE but also the functions controlled by the HPSE levels.     

Lithuanian Populations of Phytophthora infestans Revealed a High Phenotypic Diversity

Journal of Plant Diseases and Protection - This is the first characterisation of Lithuanian populations of Phytophthora infestans with mating type and virulence on a differential set of 11 R genes...     

Tree girdling provides insight on the role of labile carbon in nitrogen partitioning between soil microorganisms and adult European beech

Nitrogen (N) cycling in terrestrial ecosystems is complex since it involves the closely interwoven processes of both N uptake by plants and microbial turnover of a variety of N metabolites. Major interactions between plants and microorganisms involve competition for the same N species, provision of plant nutrients by microorganisms and labile carbon (C) supply to microorganisms by plants via root exudation. Despite these close links between microbial N metabolism and plant N uptake, only a few studies have tried to overcome isolated views of plant N acquisition or microbial N fluxes. In this study we studied competitive patterns of N fluxes in a mountainous beech forest ecosystem between both plants and microorganisms by reducing rhizodeposition by tree girdling. Besides labile C and N pools in soil, we investigated total microbial biomass in soil, microbial N turnover (N mineralization, nitrification, denitrification, microbial immobilization) as well as microbial community structure using denitrifiers and mycorrhizal fungi as model organisms for important functional groups. Furthermore, plant uptake of organic and inorganic N and N metabolite profiles in roots were determined.Surprisingly plants preferred organic N over inorganic N and nitrate (NO₃⁻) over ammonium (NH₄⁺) in all treatments. Microbial N turnover and microbial biomass were in general negatively correlated to plant N acquisition and plant N pools, thus indicating strong competition for N between plants and free living microorganisms. The abundance of the dominant mycorrhizal fungi Cenococcum geophilum was negatively correlated to total soil microbial biomass but positively correlated to glutamine uptake by beech and amino acid concentration in fine roots indicating a significant role of this mycorrhizal fungus in the acquisition of organic N by beech. Tree girdling in general resulted in a decrease of dissolved organic carbon and total microbial biomass in soil while the abundance of C. geophilum remained unaffected, and N uptake by plants was increased. Overall, the girdling-induced decline of rhizodeposition altered the competitive balance of N partitioning in favour of beech and its most abundant mycorrhizal symbiont and at the expense of heterotrophic N turnover by free living microorganisms in soil. Similar to tree girdling, drought periods followed by intensive drying/rewetting events seemed to have favoured N acquisition by plants at the expense of free living microorganisms.     

Temperature sensitivity of soil organic matter decomposition—what do we know?

Soil organic matter (SOM) represents one of the largest reservoirs of carbon on the global scale. Thus, the temperature sensitivity of bulk SOM and of different SOM fractions is a key factor determining the response of the terrestrial carbon balance to climatic warming. We condense the available knowledge about the potential temperature sensitivity and the actual temperature sensitivity of decomposition in situ, which ultimately depends on substrate availability. We review and evaluate contradictory results of estimates of the temperature sensitivity of bulk SOM and of different SOM fractions. The contradictory results demonstrate a need to focus research on biological and physicochemical controls of SOM stabilisation and destabilisation processes as a basis for understanding strictly causal relationships and kinetic properties of key processes that determine pool sizes and turnover rates of functional SOM pools. The current understanding is that temperature sensitivity of SOM mineralisation is governed by the following factors: (1) the stability of SOM, (2) the substrate availability, which is determined by the balance between input of organic matter, stabilisation and mineralisation of SOM, (3) the physiology of the soil microflora, its efficiency in substrate utilisation and its temperature optima and (4) physicochemical controls of destabilisation and stabilisation processes, like pH and limitation of water, oxygen and nutrient supply. As soil microflora is functionally omnipotent and most SOM is of high age and stability, the temperature dependence of stable SOM pools is the central question that determines C stocks and stock changes under global warming.     

Clinical evaluation of pimecrolimus eye drops for treatment of canine keratoconjunctivitis sicca: a comparison with cyclosporine A

The aim of this study was to evaluate the efficacy of pimecrolimus oil-based eye drops in alleviating the clinical signs of keratoconjunctivitis sicca (KCS) in dogs and to compare the efficacy with that of cyclosporine A (CsA) ointment. An open-label, multicenter study enrolling 44 dogs previously untreated with CsA was conducted. Dogs were randomly assigned to a treatment group and medicated twice daily for 8 weeks. After that time the mean increase (+/-SEM) in the Schirmer tear test was 9.2+/-1.6 mm/min in the pimecrolimus group and 5.8+/-1.1 mm/min in the CsA group (P=0.085). The improvement in clinical signs of inflammation in eyes treated with pimecrolimus was significantly greater than in eyes treated with CsA (P=0.02). The results show that 1% pimecrolimus oily eye drops are as safe as and more effective than CsA ointment in controlling KCS in dogs.     

D-Lactic acidosis in calves

Metabolic acidosis has long been known as a frequent and potentially severe complication of neonatal calf diarrhoea. It has also been described in 'acidosis-without-dehydration' syndrome in calves and was suspected to occur during ruminal drinking. Clinical signs of central nervous impairment, particularly changes in behaviour and posture, progressing to coma and recumbency, were originally attributed to this metabolic disturbance. The loss of bicarbonate in the faeces was regarded as the main cause of acidosis in this context. During the past decade, however, evidence has accumulated that d-lactic acidosis is a more common occurrence in calves with neonatal diarrhoea. The most probable source of D-lactataemia is bacterial fermentation of undigested substrate that reaches the large intestine due to damage to small intestinal mucosal epithelium. Recent research has shown that most of the clinical signs that were formerly attributed to acidosis were in fact due to elevated blood levels of D-lactate. The aim of this review is to provide a current overview of d-lactic acidosis.     

Economic benefits of large-scale remediation of contaminated marine sediments—a literature review and an application to the Grenland fjords in Norway

Purpose  

As input to a cost-benefit analysis of large-scale remediation measures of contaminated sediments in the Grenland fjords in Norway, we conducted a contingent valuation (CV) survey of a representative sample of households from municipalities adjacent to these fjords.     

Application of mycorrhizal roots improves growth of tropical tree seedlings in the nursery: a step towards reforestation with native species in the Andes of Ecuador

Most tree species in tropical mountain rain forests are naturally associated with arbuscular mycorrhizal fungi. Previous studies in southern Ecuador of 115 tree species revealed that only three species were not associated with arbuscular mycorrhizal fungi. Seedlings of tropical tree species raised in the nursery may need to be associated with arbuscular mycorrhizal fungi to survive transplantation shock in higher numbers. Methods for establishing plantations with native tree species are not yet established for Ecuador. Thus, we investigated the feasibility of using mycorrhizal roots of seedlings of Inga acreana, Tabebuia chrysantha, Cedrela montana and Heliocarpus americanus that had trapped mycorrhizal fungi from forest humus in the nursery to inoculate C. montana and H. americanus with native arbuscular mycorrhizal fungi. Inoculation with either a mixture of mycorrhizal roots from the four species or only with mycorrhizal roots from the same tree species were compared with effects of moderate fertilization. Assessment of plant growth and mycorrhizal status of 6-months-old Cedrela montana and Heliocarpus americanus revealed an improvement in growth and diverse associated fungi through mycorrhizal root inoculation in comparison with moderate fertilization. Moderate fertilization did not suppress mycorrhization.     

Impact of topography on cross-pollination in maize (Zea mays L.)

Understanding cross-pollination is important to achieve the coexistence of genetically modified (GM) and conventional maize (Zea mays L.); it is still not known whether topography favors or hinders cross-pollination. In 2005 and 2006, the effect of gradients of 3.4–6.8° on cross-pollination was investigated in the canton of Zurich, Switzerland. Cross-pollination was revealed by the presence of yellow-grains on a white-grain hybrid at distances up to 17.5 m from the yellow-grain pollen donor hybrid. The measurements of the inclination of the slope were based on aerial images data taken by an unmanned GPS/INS (Global Positioning System/Inertial Navigation System)-based and stabilized model helicopter, which delivered precise altitude-based data for sampling points at tassel height.The rate of cross-pollination increased significantly with decreasing altitude of the receptor field (r = 0.36–0.64). However, the effect seems to be weaker than that of other factors like wind direction and velocity.