Influence of boron toxicity on single phenols of tomato leaves

Summary Leaves of tomato plants grown in a hydroponic culture using a boron toxic solution present a different single phenols composition than those grown using an optimized nutrient solution. The absence of caffeic acid and aesculetin in boron toxic plants at flowering suggests that these compounds can be used as markers for the biochemical diagnosis of boron toxicity in tomato plants.     

Testing the usefulness of a simple automatic method for particles abundance and size determination to derive cost-effective biological indicators in large monitoring networks

A simple automatic method has been tested for biological quality assessment in coastal and estuarine waters. Samples collected in routine campaigns along the Basque coast (northern Spain) were analysed by both, a traditional microscopy technique (Utermöhl) and the flow cytometer and microscope (FlowCAM). The FlowCAM was operated in AutoImage mode (i.e. without fluorescence measurements). Two different FlowCAM procedures were carried out in two campaigns separately (2005 and 2008). These differed mainly in the lower size-threshold of the particles sampled: 10 μm in 2005, and 4 μm in 2008. The degree of divergence was evaluated, recognizing that the Utermöhl method and the FlowCAM (as employed here) count differently (i.e. phytoplankton cells and particles, respectively). In general, higher concentrations were observed with the FlowCAM (although there were some exceptions in 2005). Relationships between physico-chemical and FlowCAM variables were studied and patterns of natural variability were identified. However, a clear response to nutrient pressure was not found. It is concluded that the potential of this automatic method for deriving cost-effective indicators is limited, especially in estuaries, due to the high interference with suspended material. Further studies incorporating fluorescence measurements with the FlowCAM may be more promising. The standardization of procedures is highly recommended.     

Proteins dominate in the surface layers formed on materials exposed to extracellular polymeric substances from bacterial cultures

The chemical compositions of the surface conditioning layers formed by different types of solutions (from isolated EPS to whole culture media), involving different bacterial strains relevant for biocorrosion were compared, as they may influence the initial step in biofilm formation. Different substrata (polystyrene, glass, steel) were conditioned and analyzed by X-ray photoelectron spectroscopy. Peak decomposition and assignment were validated by correlations between independent spectral data and the ubiquitous presence of organic contaminants on inorganic substrata was taken into account. Proteins or peptides were found to be a major constituent of all conditioning layers and polysaccharides were not present in appreciable concentrations; the proportion of nitrogen which may be due to DNA was lower than 15%. There was no significant difference between the compositions of the adlayers formed from different conditioning solutions, except for the adlayers produced with tightly bound EPS extracted from D. alaskensis.     

Prostaglandins E1 and E2 stimulate release of intestinal brush border enzymes

Rat small bowel was perfused and in the absence of biliary and pancreatic secretion. Intraluminal release of sucrase, alkaline phosphatase, aminopeptidase and enterokinase was significantly increased after administration of PG E₁ and E₂ 1 and 5 μg/kg. This suggests a direct stimulation of the intestinal mucosa, which might be mediated through cyclic AMP ; dibutyryl cAMP significantly stimulates intraluminal release of proteins, sucrase and enterokinase.     

Elastogenesis in rat arterial grafts: elastin deposits on microfibrillar and non-microfibrillar structures

Summary Endothelial lesions and the subsequent migration of smooth muscle cells in the intima layer are frequently observed after vascular grafting. The expression of secretory phenotype by these cells leads to the accumulation of connective tissue and thereby provides a model for the study of elastin depositionin vivo. Rats bearing aortic grafts of auto-, iso- or homologous origin were sacrificed between 3 and 18 months after implantation. Samples were treated for routine ultrastructural observations and for post-embedding by immunoelectron microscopy using anti-human elastin and protein A-gold.Grafts showed a large intimal thickening composed of several layers of smooth muscle cells and an abundant extracellular matrix. Mature elastic fibres (amorphous elastin associated with peripheral microfibrils) were always encountered in hyperplasia, suggesting that elastin deposition may follow the classical pathway involving microfibrils, which serve as a framework for polymerization of tropoelastin molecule into the amorphous component. However, an unusual localization of elastin aggregates was observed within basement membrane-like material surrounding smooth muscle cells. When sections were stained with methanolic uranyl acetate, these areas showed small electron-dense bodies, which were also labelled with anti-elastin antibody. These structures were apparently devoid of surrounding microfibrils. These results indicate that non-microfibrillar basement membrane material might be involved in the early events of elastin deposition.     

AtFXG1, an Arabidopsis gene encoding alpha-L-fucosidase active against fucosylated xyloglucan oligosaccharides.

An alpha-L-fucosidase (EC 3.2.1.51) able to release the t-fucosyl residue from the side chain of xyloglucan oligosaccharides has been detected in the leaves of Arabidopsis plants. Moreover, an alpha-L-fucosidase with similar substrate specificity was purified from cabbage (Brassica oleracea) leaves to render a single band on SDS-PAGE. Two peptide sequences were obtained from this protein band, and they were used to identify an Arabidopsis gene coding for an alpha-fucosidase that we propose to call AtFXG1. In addition, an Arabidopsis gene with homology with known alpha-L-fucosidases has been also found, and we proposed to name it as AtFUC1. Both AtFXG1 and ATFUC1 were heterologously expressed in Pichia pastoris cells and the alpha-L-fucosidase activities secreted to the culture medium. The alpha-L-fucosidase encoded by AtFXG1 was active against the oligosaccharides from xyloglucan XXFG as well as against 2'-fucosyl-lactitol but not against p-nitrophenyl-alpha-L-fucopyranoside. However, the AtFUC1 heterologously expressed was active only against 2'-fucosyl-lactitol. Thus, the former must be related to xyloglucan metabolism.     

The Role of the Anaphase-Promoting Complex/Cyclosome in Plant Growth

The anaphase-promoting complex/cyclosome (APC/C) is a multi-subunit E3 ubiquitin ligase that plays a major role in the progression of the eukaryotic cell cycle. This unusual protein complex targets key cell cycle regulators, such as mitotic cyclins and securins, for degradation via the 26S proteasome by ubiquitination, triggering the metaphase-to-anaphase transition and exit from mitosis. Because of its essential role in cell cycle regulation, the APC/C has been extensively studied in mammals and yeasts, but relatively less in plants. Evidence shows that, besides its well-known role in cell cycle regulation, the APC/C also has functions beyond the cell cycle. In metazoans, the APC/C has been implicated in cell differentiation, disease control, basic metabolism and neuronal survival. Recent studies also have shed light on specific functions of the APC/C during plant development. Plant APC/C subunits and activators have been reported to play a role in cellular differentiation, vascular development, shoot branching, female and male gametophyte development and embryogenesis. Here, we discuss our current understanding of the APC/C controlling plant growth.     

Variability in life‐history and ecological traits is a buffer against extinction in mammals

Anthropogenic degradation of the world's ecosystems is leading to a widespread and accelerating loss of biodiversity. However, not all species respond equally to existing threats, raising the question: what makes a species more vulnerable to extinction? We propose that higher intraspecific variability may reduce the risk of extinction, as different individuals and populations within a species may respond differently to occurring threats. Supporting this prediction, our results show that mammalian species with more variable adult body masses, litter sizes, sexual maturity ages and population densities are less vulnerable to extinction. Our findings reveal the role of local variation among populations, particularly of large mammals, as a buffering mechanism against extinction, and emphasise the importance of considering trait variation in comparative analyses and conservation management.     

Human-related factors regulate the spatial ecology of domestic cats in sensitive areas for conservation

Background

Domestic cats ranging freely in natural areas are a conservation concern due to competition, predation, disease transmission or hybridization with wildcats. In order to improve our ability to design effective control policies, we investigate the factors affecting their numbers and space use in natural areas of continental Europe.

Methodology/Principal Findings

We describe the patterns of cat presence, abundance and space use and analyse the associated environmental and human constraints in a well-preserved Mediterranean natural area with small scattered local farms. We failed in detecting cats in areas away from human settlements (trapping effort above 4000 trap-nights), while we captured 30 individuals near inhabited farms. We identified 130 cats, all of them in farms still in use by people (30% of 128 farms). All cats were free-ranging and very wary of people. The main factor explaining the presence of cats was the presence of people, while the number of cats per farm was mostly affected by the occasional food provisioning with human refuse and the presence of people. The home ranges of eight radio tagged cats were centred at inhabited farms. Males went furthest away from the farms during the mating season (3.8 km on average, maximum 6.3 km), using inhabited farms as stepping-stones in their mating displacements (2.2 km of maximum inter-farm distance moved). In their daily movements, cats notably avoided entering in areas with high fox density.

Conclusions

The presence, abundance and space use of cats were heavily dependent on human settlements. Any strategy aiming at reducing their impact in areas of conservation concern should aim at the presence of settlements and their spatial spread and avoid any access to human refuse. The movements of domestic cats would be limited in areas with large patches of natural vegetation providing good conditions for other carnivore mammals such as red foxes.