Mycotoxin production by Fusarium avenaceum strains isolated from Norwegian grain and the cytotoxicity of rice culture extracts to porcine kidney epithelial cells

The secondary metabolites of 24 isolates of Fusarium avenaceum from Norwegian cereals and grown on rice have been characterized. Moniliformin (MON), enniatins (ENNs), and beauvericin (BEA) were analyzed by high-performance liquid chromatography. Porcine kidney epithelial cells (PK15, American Type Culture Collection) were used to study the cytotoxicity of MON in the extracts. The following metabolites were produced by all isolates, ranked by concentration in rice cultures: ENN-B, MON, ENN-B1, and ENN-A. BEA was produced by eight isolates. The productions of BEA and ENN-A were significantly correlated, as was the case with ENN-B and ENN-B1. MON production was correlated neither to any of the other toxins nor to toxicity.     

Video-rate far-field optical nanoscopy dissects synaptic vesicle movement

We present video-rate (28 frames per second) far-field optical imaging with a focal spot size of 62 nanometers in living cells. Fluorescently labeled synaptic vesicles inside the axons of cultured neurons were recorded with stimulated emission depletion (STED) microscopy in a 2.5-micrometer by 1.8-micrometer field of view. By reducing the cross-sectional area of the focal spot by about a factor of 18 below the diffraction limit (260 nanometers), STED allowed us to map and describe the vesicle mobility within the highly confined space of synaptic boutons. Although restricted within boutons, the vesicle movement was substantially faster in nonbouton areas, consistent with the observation that a sizable vesicle pool continuously transits through the axons. Our study demonstrates the emerging ability of optical microscopy to investigate intracellular physiological processes on the nanoscale in real time.     

The structural organization of the readily releasable pool of synaptic vesicles

The defining morphological feature of chemical synapses is the vesicle cluster in the presynaptic nerve terminal. It has generally been assumed that vesicles closest to release sites are recruited first during nerve activity. We tested this by selectively labeling the "readily releasable" pool, those vesicles released first during physiological stimulation. The readily releasable vesicles were not clustered close to the presynaptic membrane but instead were dispersed almost randomly throughout the vesicle cluster. Thus, vesicles are not recruited according to proximity to release sites but are mobilized differently, perhaps by being peeled from the surface of the cluster.     

Deep weathering and landscape evolution in a tropical plateau

The thick weathering profiles of humid tropical areas are an important, yet generally neglected, source of information on landscape evolution. Six complete profiles of the weathering mantle were sampled by drilling on the three stepped levels of the Campos do Jordão Plateau, on the NW flank of the Continental Rift of Southeastern Brazil. Mineralogical and micromorphological analyses of drill core samples, complemented by geochemical interpretations and by previous data on the upper saprolite, indicate continuity of a general lateritic trend during the entire process of mantle formation. Lateritization phases of different intensity were defined and considered to reflect adjustment to changes in environmental conditions created by the gradual uplift of the plateau to its present position. Older and more superficial materials related to intense lateritic weathering are characterized by allitization with direct formation of gibbsite from silicates, probably related to tropical climates existing immediately before the formation of the continental rift, during the Paleogene, and also before any significant increase in altitude. Monosialitization phase with general kaolinitization and restricted indirect formation of gibbsite from silicates could be associated to less aggressive climates that followed the Neogene (Miocene?) accentuation of uplift rates along the continental rift. The changes produced by uplift in the tropical climate eventually favored the development of a podzolization trend in soils above 1800 m.     

Augmented Wnt signaling in a mammalian model of accelerated aging

The contribution of stem and progenitor cell dysfunction and depletion in normal aging remains incompletely understood. We explored this concept in the Klotho mouse model of accelerated aging. Analysis of various tissues and organs from young Klotho mice revealed a decrease in stem cell number and an increase in progenitor cell senescence. Because klotho is a secreted protein, we postulated that klotho might interact with other soluble mediators of stem cells. We found that klotho bound to various Wnt family members. In a cell culture model, the Wnt-klotho interaction resulted in the suppression of Wnt biological activity. Tissues and organs from klotho-deficient animals showed evidence of increased Wnt signaling, and ectopic expression of klotho antagonized the activity of endogenous and exogenous Wnt. Both in vitro and in vivo, continuous Wnt exposure triggered accelerated cellular senescence. Thus, klotho appears to be a secreted Wnt antagonist and Wnt proteins have an unexpected role in mammalian aging.     

Phytotoxicity of Biosolids Compost at Different Degrees of Maturity Compared to Biosolids and Animal Manures

Biosolids compost is a good organic amendment but immature compost can exhibit phytotoxic behavior which can be attributed to different toxic substances. Our objective was to determine the phytotoxicity of: i) Biosolids; ii) Mix of biosolids and wood sawdust sampled a day after composting started; iii) The same material sampled at the end of the thermophilic stage; iv) cured compost; v) cow manure and vi) horse manure A germination bioassay was carried out using Lolium perenne (ryegrass) seeds: germination and root growth percentage were determined as well as electrical conductivity, pH, phenol content and volatile organic acids. In three treatments, Ni, Pb, Zn, Cu and Cd were also determined. Ammonia volatilization was determined during biosolids composting. The germination percentage varied from 67% to 95% but the inhibition of root growth appears to be a more sensitive phytotoxicity indicator (18% to 74%. Phytotoxic effects on germinating ryegrass were mainly related to extract pH and electrical conductivity. Potentially toxic elements, volatile organic acids, phenolic compounds and ammonia were not related to germination.     

Distribution,abundance, and movements of the bottlenose dolphin (Tursiops truncatus) in the Pelagos Sanctuary MPA (north‐west Mediterranean Sea)

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How good are tropical forest patches for ecosystem services provisioning?

Native forests play an important role regarding ecosystem services related to biodiversity, water, and nutrient cycling, and the intensity of those services should be related to the amount, configuration and quality of the forest. However, in highly dynamic landscapes, such as some tropical regions, ecosystem services are potentially affected not only by the present landscape structure, but also by the historical land use. Here we propose a simple methodological framework to evaluate the contribution of past landscape dynamics and present landscape structure in the provision of ecosystem services. We applied this framework to a traditional agricultural landscape from the Brazilian Atlantic Forest hotspot, where natural forests cover has increased from 8 to 16 % in the last 60 years (1962–2008), and where old forests are being reduced while young forests are being regenerated. Forests of different ages, in association with current landscape structure, reveal a mosaic of forest patches under different conditions, implying different abilities to deliver ecosystem services. With the replacement of old-growth forests by young-regenerating forests and a high level of forest fragmentation, less than 1/4 of the current forest cover is able to fully satisfy the ecosystem service demands. To avoid such tendency, government policies should not only focus on increasing forest cover, but also in conserving old-growth forest fragments or increasing forest quality. The proposed methodology allows integrating historical land use and current landscape structure to evaluate ecosystem services provision and can be useful to establish programs of payment for ecosystem services.     

A review of the roles of forest canopy gaps

Treefall gap, canopy opening caused by the death of one or more trees, is the dominant form of disturbance in many forest systems worldwide. Gaps play an important role in forest ecology helping to pre- serve bio- and pedo-diversity, influencing nutrient cycles, and maintain- ing the complex structure of the late-successional forests. Over the last 30 years, numerous reviews have been written describing gap dynamics. Here we synthesize current understanding on gap dynamics relating to tree regeneration with particular emphasis on gap characteristics consid- ered critical to develop ecologically sustainable forest management sys- tems and to conserve native biodiversity. Specifically, we addressed the question： how do gaps influence forest structure？ From the literature re- viewed, the size of gaps induces important changes in factors such as light intensity, soil humidity and soil biological properties that influence tree species regeneration and differ in gaps of different sizes. Shade- tolerant species can colonize small gaps; shade-intolerant species need large gaps for successful regeneration. Additionally, gap dynamics differ between temperate, boreal, and tropical forests, showing the importance of climate differences in driving forest regeneration. This review summa- rizes information of use to forest managers who design cutting regimes that mimic natural disturbances and who must consider forest structure, forest climate, and the role of natural disturbance in their designs.     

Characterization of Palytoxin Binding to HaCaT Cells Using a Monoclonal Anti-Palytoxin Antibody

Palytoxin (PLTX) is the reference compound for a group of potent marine biotoxins, for which the molecular target is Na⁺/K⁺-ATPase. Indeed, ouabain (OUA), a potent blocker of the pump, is used to inhibit some PLTX effects in vitro. However, in an effort to explain incomplete inhibition of PLTX cytotoxicity, some studies suggest the possibility of two different binding sites on Na⁺/K⁺-ATPase. Hence, this study was performed to characterize PLTX binding to intact HaCaT keratinocytes and to investigate the ability of OUA to compete for this binding. PLTX binding to HaCaT cells was demonstrated by immunocytochemical analysis after 10 min exposure. An anti-PLTX monoclonal antibody-based ELISA showed that the binding was saturable and reversible, with a K_d of 3 × 10⁻¹⁰ M. However, kinetic experiments revealed that PLTX binding dissociation was incomplete, suggesting an additional, OUA-insensitive, PLTX binding site. Competitive experiments suggested that OUA acts as a negative allosteric modulator against high PLTX concentrations (0.3–1.0 × 10⁻⁷ M) and possibly as a non-competitive antagonist against low PLTX concentrations (0.1–3.0 × 10⁻⁹ M). Antagonism was supported by PLTX cytotoxicity inhibition at OUA concentrations that displaced PLTX binding (1 × 10⁻⁵ M). However, this inhibition was incomplete, supporting the existence of both OUA-sensitive and -insensitive PLTX binding sites.