ATP-competitive,marine derived natural products that target the DEAD box helicase,eIF4A

Activation of translation initiation is a common trait of cancer cells. Formation of the heterotrimeric eukaryotic initiation factor F (eIF4F) complex is the rate-limiting step in 5′ m7GpppN cap-dependent translation. This trimeric complex includes the eIF4E cap binding protein, the eIF4G scaffolding protein, and the DEAD box RNA helicase eIF4A. eIF4A is an ATP-dependent helicase and because it is the only enzyme in the eIF4F complex, it has been shown to be a potential therapeutic target for a variety of malignancies. To this end, we have used a simple ATPase biochemical screen to survey several hundred marine and terrestrial derived natural products. Herein, we report the discovery of two natural products from marine sources, elisabatin A (1) and allolaurinterol (2), which show low µM inhibition of eIF4A ATPase activity. Enzymological analyses revealed 1 and 2 to be ATP-competitive, and cellular evaluations showed reasonable cytotoxicity against A549 (lung cancer) and MDA-MA-468 (breast cancer) cell lines. However, only compound 2 showed potent inhibition of helicase activity congruent with its ATPase inhibitory activity.     

Novel anti-prostate cancer scaffold identified by the combination of in silico and cell-based assays targeting the PI3K-AKT-mTOR pathway

Phenotypic assays were performed in prostate cancer cell lines to describe the biological activity of PI3K-AKT-mTOR pathway inhibitors retrieved from the virtual screening initiative. These novel chemicals share in common the aminopyridine scaffold, hitting PC-3 cells in macromolar range, with selectivity index over fibroblast cell lines. Moreover, a preliminary study of the mode of action by flow cytometry assay pointed out that these compounds had a rapamycin-like response for the PI3K-AKT-mTOR pathway modulation.     

Comparative landscape genetics of pond‐breeding amphibians in Mediterranean temporal wetlands: The positive role of structural heterogeneity in promoting gene flow

Comparative landscape genetics studies can provide key information to implement cost‐effective conservation measures favouring a broad set of taxa. These studies are scarce, particularly in Mediterranean areas, which include diverse but threatened biological communities. Here, we focus on Mediterranean wetlands in central Iberia and perform a multi‐level, comparative study of two endemic pond‐breeding amphibians, a salamander (Pleurodeles waltl) and a toad (Pelobates cultripes). We genotyped 411 salamanders from 20 populations and 306 toads from 16 populations at 18 and 16 microsatellite loci, respectively, and identified major factors associated with population connectivity through the analysis of three sets of variables potentially affecting gene flow at increasingly finer levels of spatial resolution. Topographic, land use/cover, and remotely sensed vegetation/moisture indices were used to derive optimized resistance surfaces for the two species. We found contrasting patterns of genetic structure, with stronger, finer scale genetic differentiation in Pleurodeles waltl, and notable differences in the role of fine‐scale patterns of heterogeneity in vegetation cover and water content in shaping patterns of regional genetic structure in the two species. Overall, our results suggest a positive role of structural heterogeneity in population connectivity in pond‐breeding amphibians, with habitat patches of Mediterranean scrubland and open oak woodlands (“dehesas”) facilitating gene flow. Our study highlights the usefulness of remotely sensed continuous variables of land cover, vegetation and water content (e.g., NDVI, NDMI) in conservation‐oriented studies aimed at identifying major drivers of population connectivity.     

Local lithological drivers of post-fire vegetation recovery and implications for fire-prone regions

Local ecosystem resilience to fire disturbance can be influenced by multiple factors, from topography and climate, to fire history and pre-fire structure of biotic communities. Here we investigated the factors affecting post-fire recovery of scrub vegetation in areas under Mediterranean climate affected by frequent fires. We hypothesized that, under comparable climatic and topographic conditions, geological factors (with bedrock type as a proxy) would be at least as important as fire history in explaining patterns of post-fire recovery. We surveyed scrub vegetation in a mountain study area in Portugal, using a stratified random sampling scheme, with fire frequency, time since last fire, and bedrock type (granite vs. schist) as stratifying layers. Based on vegetation and plant community data from 40 plots, we analyzed total species richness and composition, and the relative abundance of functional groups defined on the basis of general (non fire-specific) life-history traits. We found that, at a local scale, lithology can override fire history in determining post-fire recovery. Vegetation plots on granite exhibited a considerable development of tall scrubs and higher values of total species richness. They also hosted higher numbers of animal-dispersed woody species, of trees and tall scrubs, of woody deciduous species, and of forest, edge and tall scrub species. Differences in the post-fire development of scrub vegetation and in the functional profile of plant communities highlight the need to consider local geological diversity when establishing priorities for post-fire active restoration under scenarios of limited resources.     

Therapeutic efficacy in BALB/C mice of extract from marine alga <Emphasis Type="Italic">Canistrocarpus cervicornis</Emphasis> (Phaeophyceae) against herpes simplex virus type 1

Studies with diterpenes from marine brown alga Canistrocarpus cervicornis showed the antiviral potential of the products from this alga in controlling the replication of HSV-1 and maintaining low cytotoxicity. Hence, the aim of this work was to evaluate the anti-herpetic efficacy of C. cervicornis extract ointment in BALB/c mice. To test the anti-herpetic efficacy in vivo, four groups of BALB/c mice (n?=?5) were used: 1—untreated, 2—extract ointment (2 % or 0.4 mg cm^?2 dose^?1), 3—Acyclovir cream (5 % or 1.0 mg cm^?2 dose^?1), and 4—ointment base. The right midflank of each mouse was clipped and depilated with a chemical depilatory. After 2 days, the skin area was scratched and inoculated with HSV-1. The ointments and cream were applied three times a day over a 16-day period, beginning 1 h after virus inoculation. The development of skin lesions was continuously monitored and scored. To evaluate the effect of C. cervicornis topical treatment on biochemical parameters and on body weight, two uninfected groups were formed: an untreated group and a group treated with ointment C. cervicornis extract (2 %). The signs of infection appeared from the second day after infection, while on the 10th day of the experiment, the ointment base and untreated groups had significantly more severe lesions than did the groups that were treated with extract (p?<?0.05) or acyclovir (p?<?0,01). The topical application of extract ointment did not change body weight, hepatic, or renal function suggesting that the extract has a low toxicity in this route of administration. These results suggest that the extract may be useful in reducing the severity of HSV-1 cutaneous lesions.     

Intermittency in the Hodgkin-Huxley model

We show that action potentials in the Hodgkin-Huxley neuron model result from a type I intermittency phenomenon that occurs in the proximity of a saddle-node bifurcation of limit cycles. For the Hodgkin-Huxley spatially extended model, describing propagation of action potential along axons, we show the existence of type I intermittency and a new type of chaotic intermittency, as well as space propagating regular and chaotic diffusion waves. Chaotic intermittency occurs in the transition from a turbulent regime to the resting regime of the transmembrane potential and is characterised by the existence of a sequence of action potential spikes occurring at irregular time intervals.     

Description and identification of two new diseases of guariroba palm (Syagrus oleraceae) in Brazil

Guariroba is a palm species native to central Brazil. Seedlings of guariroba with leaf spots of unknown aetiology were found in Patos de Minas, Minas Gerais, Brazil. The leaf spots were manifest as two different symptom types: the first lesion type consisted of necrotic spots with a rounded to elongate shape, with a light colour and dark edges; the second lesion type had a rounded shape, was dark brown in colour with a light brown edge. The objective of this study was to elucidate the aetiology of both diseases. The likely causal agents were isolated and Koch's postulate fulfilled. Subsequently, the ITS region of rDNA from both micro‐organisms were amplified and sequenced. According to the morphological characteristics and molecular analyses, the fungal species were identified as Pestalotiopsis adusta (causing necrotic spots with a rounded to elongate shape, with a light colour and dark edges), and Alternaria tenuissima (causing lesions with a rounded shape, dark brown in colour with a light brown edge). Identification of the causal organisms of these two diseases will help guide management approaches that might be tested to reduce impact of the disease on Guariroba, including the use of fungicides and cultural approaches.     

A flexible parametric model for a balanced account of forest carbon fluxes in LCA

Purpose

Despite a mature debate on the importance of a time-dependent account of carbon fluxes in life cycle assessments (LCA) of forestry products, static accounts of fluxes are still common. Time-explicit inventory of carbon fluxes is not available to LCA practitioners, since the most commonly used life cycle inventory (LCI) databases use a static approach. Existing forest models are typically applied to specific study fields for which the detailed input parameters required are available. This paper presents a simplified parametric model to obtain a time-explicit balanced account of the carbon fluxes in a forest for use in LCA. The model was applied to the case of spruce as an example.

Methods

The model calculated endogenous and exogenous carbon fluxes in tons of carbon per hectare. It was designed to allow users to choose (a) the carbon pools to be included in the analysis (aboveground and belowground carbon pools, only aboveground carbon or only carbon in stem); (b) a linear or sigmoidal dynamic function describing biomass growth; (c) a sigmoidal, negative exponential or linear dynamic function describing independently the decomposition of aboveground and belowground biomass; and (d) the forest management features such as stand type, rotation time, thinning frequency and intensity.

Results and discussion

The parametric model provides a time-dependent LCI of forest carbon fluxes per unit of product, taking into account the typically limited data available to LCA practitioners, while providing consistent and robust outcomes. The results obtained for the case study were validated with the more complex CO2FIX. The model ensures carbon balance within spatial and time delimitation defined by the user by accounting for the annual biomass degradation and production in each carbon pool. The inventory can be used in LCA studies and coupled with classic indicators (e.g. global warming potential) to accurately determine the climate impacts over time. The model is applicable globally and to any forest management practice.

Conclusions

This paper proposes a simplified and flexible forest model, which facilitates the implementation in LCA of time-dependent assessments of bio-based products.

     

Successional patterns of key genes and processes involved in the microbial nitrogen cycle in a salt marsh chronosequence

Here, we investigated the patterns of microbial nitrogen cycling communities along a chronosequence of soil development in a salt marsh. The focus was on the abundance and structure of genes involved in N fixation (nifH), bacterial and archaeal ammonium oxidation (amoA; AOB and AOA), and the abundances of genes involved in denitrification (nirS, nirK, nosZ). Potential nitrification and denitrification activities were also measured, and increases in nitrification were found in soils towards the end of succession, whereas denitrification became maximal in soils at the intermediate stages. The nifH, nirK and nirS gene markers revealed increases in the sizes of the respective functional groups towards the intermediate stage (35 years), remaining either constant (for nifH) or slightly declining towards the latest stage of succession (for nirK and nirS). Moreover, whereas the AOB abundance peaked in soils at the intermediate stage, that of AOA increased linearly along the chronosequence. The abundance of nosZ was roughly constant, with no significant regression. The drivers of changes in abundance and structure were identified using path analysis; whereas the ammonia oxidizers (AOA and AOB) showed patterns that followed mainly N availability, those of the nitrogen fixers followed plant diversity and soil structure. The patterns of denitrifiers were group-dependent, following the patterns of plant diversity (nirK and nirS) and belowground shifts (nosZ). The variation observed for the microbial groups associated with the same function highlights their differential contribution at different stages of soil development, revealing an interplay of changes in terms of niche complementarity and adaptation to the local environment.