Transcriptome profiling helps to identify potential and true molecular switches of stealth to brute force behavior in <Emphasis Type="Italic">Pectobacterium atrosepticum</Emphasis> during systemic colonization of tobacco plants

In the present study, we have monitored the process of systemic plant colonization by the plant pathogenic bacterium Pectobacterium atrosepticum (Pba) using RNA-Seq analysis in order to compare bacterial traits under in planta and in vitro conditions and to reveal potential players that participate in switching from stealth to brute force strategy of the pathogen. Two stages of tobacco plant colonization have been assayed: i) the initial one associated with visually symptomless spread of bacteria throughout the host body via primary xylem vessels where bacterial emboli were formed (stealth strategy), and ii) the advanced stage coupled with an extensive colonization of core parenchyma and manifestation of soft rot symptoms (brute force strategy). Plant-inducible genes in Pba and potential players switching the pathogen’s behavior were revealed. Genes from the cfa locus responsible for the production of coronafacic acid displayed the strongest induction in the asymptomatic zone relative to the symptomatic one and were shown experimentally to act as the true strategy “switchers” of Pba behavior in planta. Surprisingly, cfa genes appeared to be unnecessary for establishment of the asymptomatic stage of plant colonization but were required for the transition to soft-rot-associated symptomatic stage coupled with over-induction of jasmonate-mediated pathway in the plant.     

Measurement and simulation of evaporation from soil in olive orchards

Evaporation from the soil (E _s) beneath an olive orchard was characterised in a semi-arid Mediterranean climate (Córdoba, Spain). First, the microlysimeter method was modified to measure accurately E _s beneath tree orchards. The variability in irradiance reaching the soil beneath the orchard caused spatial variations in E _s during both evaporation stages. In the first days of the drying cycle, E _s was higher for high irradiance locations but the opposite occurred the subsequent days, although daily differences in E _s between locations progressively declined. For the energy-limiting stage, linear relationships between E _s values and incident photosynthetically active radiation were found for different times throughout the season. The slopes of the relationships were similar, but their intercepts differed substantially, showing the importance of a variable aerodynamic component in determining E _s. A simple functional model was formulated to estimate E _s at daily time steps. During the energy-limiting stage, E _s is calculated as the sum of the equilibrium evaporation at the soil surface and an aerodynamic term, derived from the Penman equation. For the falling rate stage, Ritchie's (1972) approach is adopted for the E _s calculations. The model was successfully tested in an orchard of 6×6 m spacing, typical of intensive olive orchards, under a wide range of evaporative demand conditions. Trees covered around 36% of the soil surface. The model predicted an average seasonal E _s of 286 mm, which represents around one third of the estimated olive evapotranspiration and about 50% of the average seasonal rainfall of the area. Received: 3 August 1998     

An Alternative Approach towards C-12 Functionalized Scalaranic Sesterterpenoids Synthesis of 17-Oxo-20-norscalaran-12α,19-O-lactone

Scalarane sesterterpenoids emerged as interesting bioactive natural products which were isolated extensively from marine sponges and shell-less mollusks. Some representatives were also reported recently from superior plants. Many scalarane sesterterpenoids displayed a wide spectrum of valuable properties, such as antifeedant, antimicrobial, antifungal, antitubercular, antitumor, anti-HIV properties, cytotoxicity and stimulation of nerve growth factor synthesis, as well as anti-inflammatory activity. Due to their important biological properties, many efforts have been undertaken towards the chemical synthesis of natural scalaranes. The main synthetic challenges are connected to their complex polycyclic framework, chiral centers and different functional groups, in particular the oxygenated functional groups at the C-12 position, which are prerequisites of the biological activity of many investigated scalaranes. The current work addresses this problem and the synthesis of 17-oxo-20-norscalaran-12α,19-O-lactone is described. It was performed via the 12α-hydroxy-ent-isocopal-13(14)-en-15-al obtained from (-)-sclareol as an accessible starting material. The tetracyclic lactone framework was built following an addition strategy, which includes the intramolecular Michael addition of a diterpenic acetoacetic ester and an intramolecular aldol condensation reaction as key synthetic steps. The structure and stereochemistry of the target compound have been proven by X-Ray diffraction method.     

Identifying environmental drivers of spatial genetic structure of the European pine marten (<Emphasis Type="Italic">Martes martes</Emphasis>)

Context

In a global context of erosion of biodiversity, the current environmental policy in Europe is oriented towards the creation and the preservation of ecological networks for wildlife. However, most of the management guidelines arose from a structural landscape diagnostic without truly taking into consideration species’ needs.

Objectives

We tested whether and how landscape elements influence the functional connectivity of landscapes for a forest specialist species, the European pine marten (Martes martes), in Northeastern France.

Methods

We collected pine marten scats and tissues from 13 evenly distributed study sites across the whole study area in order to test several types of barriers such as highways, waterways, and open agricultural fields. We crossed the results of several methods: spatial autocorrelation analysis, causal modelling framework, and clustering methods.

Results

The study indicates significant genetic differentiation among the sampling sites. A signal of isolation by distance was detected but disappeared after partialling out landscape or barrier resistance. The only model that was fully supported by causal modelling was the one identifying waterways as the main driver of genetic differentiation. Moreover, clustering analyses indicated the presence of genetic clusters, suggesting that pine marten spatial genetic pattern could be explained by the presence of waterways but also by their reluctance to cross open fields.

Conclusions

The current ecological network could thus be improved by increasing permeability of waterways, in particular navigation canals, and by maintaining and restoring forested corridors in agricultural plains.

     

Roe enhancement of Paracentrotus lividus: Nutritional effects of fresh and formulated diets

Sea urchin gonads are exploited both for gastronomic and scientific purposes; thus, the production of large and mature gonads is essential. Natural populations of the Mediterranean Sea urchin Paracentrotus lividus are subject to increasing fishing efforts, due to continuous intensification of consumptions. Aquaculture practices may represent an answer, but the availability of artificial feeds accelerating the production of high‐quality gonads in terms of size, taste, colour, firmness, maturity and viability of gametes is critical to boost the productions. The accessibility of cheap and effective feeds promoting the fattening of gonads and the quality of gametes is still a bottleneck slowing down the expansion of echinoculture practices. This investigation is aimed at enabling the development of this strategic sector, by comparing the dietetic effects of fresh foods and a commercial feed for aquaculture, to four newly formulated feeds. The protein contents of diets were strongly related to the GSIs. The abundance of fatty acids appeared inversely related to the viability of embryos and abnormalities of larvae. The features of an ideal diet for this sea urchin were defined, based on the results of experimental trials, and the need for increasing levels of plant‐derived proteins during the grow‐out period was demonstrated.     

How much carbon can the Siberian boreal taiga store: a case study of partitioning among the above-ground and soil pools

In the context of global carbon cycle management, accurate knowledge of carbon content in forests is a relevant issue in contemporary forest ecology. We measured the above-ground and soil carbon pools in the darkconiferous boreal taiga. We compared measured carbon pools to those calculated from the forest inventory records containing volume stock and species composition data. The inventory data heavily underestimated the pools in the study area(Stolby State Nature Reserve, central Krasnoyarsk Territory, Russian Federation). The carbon pool estimated from the forest inventory data varied from 25(t ha-1)(low-density stands) to 73(t ha-1)(highly stocked stands). Our estimates ranged from 59(t ha-1)(lowdensity stands) to 147(t ha-1)(highly stocked stands). Our values included living trees, standing deadwood, living cover, brushwood and litter. We found that the proportion of biomass carbon(living trees): soil carbon varied from99:1 to 8:2 for fully stocked and low-density forest stands,respectively. This contradicts the common understanding that the biomass in the boreal forests represents only16–20 % of the total carbon pool, with the balance being the soil carbon pool.     

Capsaicin in Hot Chili Peppers: In Vitro Evaluation of Its Antiradical,Antiproliferative and Apoptotic Activities

Plant Foods for Human Nutrition - Capsaicin is a spicy capsaicinoid, produced as secondary metabolite by Capsicum fruits. This alkaloid has been used for years in folk medicine for its analgesic...     

Disentangling data dependency using cross-validation strategies to evaluate prediction quality of cattle grazing activities using machine learning algorithms and wearable sensor data

Wearable sensors have been explored as an alternative for real-time monitoring of cattle feeding behavior in grazing systems. To evaluate the performance of predictive models such as machine learning (ML) techniques, data cross-validation (CV) approaches are often employed. However, due to data dependencies and confounding effects, poorly performed validation strategies may significantly inflate the prediction quality. In this context, our objective was to evaluate the effect of different CV strategies on the prediction of grazing activities in cattle using wearable sensor (accelerometer) data and ML algorithms. Six Nellore bulls (average live weight of 345 ± 21 kg) had their behavior visually classified as grazing or not-grazing for a period of 15 d. Elastic Net Generalized Linear Model (GLM), Random Forest (RF), and Artificial Neural Network (ANN) were employed to predict grazing activity (grazing or not-grazing) using 3-axis accelerometer data. For each analytical method, three CV strategies were evaluated: holdout, leave-one-animal-out (LOAO), and leave-one-day-out (LODO). Algorithms were trained using similar dataset sizes (holdout: n = 57,862; LOAO: n = 56,786; LODO: n = 56,672). Overall, GLM delivered the worst prediction accuracy (53%) compared with the ML techniques (65% for both RF and ANN), and ANN performed slightly better than RF for LOAO (73%) and LODO (64%) across CV strategies. The holdout yielded the highest nominal accuracy values for all three ML approaches (GLM: 59%, RF: 76%, and ANN: 74%), followed by LODO (GLM: 49%, RF: 61%, and ANN: 63%) and LOAO (GLM: 52%, RF: 57%, and ANN: 57%). With a larger dataset (i.e., more animals and grazing management scenarios), it is expected that accuracy could be increased. Most importantly, the greater prediction accuracy observed for holdout CV may simply indicate a lack of data independence and the presence of carry-over effects from animals and grazing management. Our results suggest that generalizing predictive models to unknown (not used for training) animals or grazing management may incur poor prediction quality. The results highlight the need for using management knowledge to define the validation strategy that is closer to the real-life situation, i.e., the intended application of the predictive model.