Pollen starch reserves in tomato relatives: Ecophysiological implications

The presence or absence of starch in microspore development and in pollen grains was recorded in eleven wild tomato species (Solanum sect. Lycopersicon) and two close relatives (S. lycopersicoides and S. sitiens). In all the species starch started to accumulate in the early microspore bicellular stage and continued until the cytoplasm was filled. At flower anthesis, pollen grains were mostly starchless in the wild tomatoes, except in S. pennellii, which had starchy pollen. Starchy pollen is also present in the two related species. The latter two species had larger pollen grains and grow in drier environments than the other species. The heterogeneity of pollen starch content among all these species, supposed to have the same pollination mechanism, is a new finding supporting the idea that starch content and pollination mechanism do not necessarily influence each other. The presence of starchy pollen in the self‐incompatible species, which grow in the driest environments, raises questions regarding the relationship between carbohydrates content and pollen survival.     

Crystal structure of chicken liver basic fatty acid-binding protein complexed with cholic acid

Two paralogous groups of liver fatty acid-binding proteins (FABPs) have been described: the mammalian type liver FABPs and the basic type (Lb-FABPs) characterized in several vertebrates but not in mammals. The two groups have similar sequences and share a highly conserved three-dimensional structure, but their specificity and stoichiometry of binding are different. The crystal structure of chicken Lb-FABP complexed with cholic acid and that of the apoprotein refined to 2.0 A resolution are presented in this paper. The two forms of the protein crystallize in different space groups, and significant changes are observed between the two conformations. The holoprotein binds two molecules of cholate in the interior cavity, and the contacts observed between the two ligands can help to explain the reason for this stoichiometry of binding. Most of the amino acids involved in ligand binding are conserved in other members of the Lb-FABP family. Since the amino acid sequence of the Lb-FABPs is more similar to that of the bile acid-binding proteins than to that of the L-FABPs, the possibility that the Lb-FABPs might be more appropriately called liver bile acid-binding proteins (L-BABPs) is suggested.     

Molecular biomarkers in the subsurface of the Salar Grande (Atacama,Chile) evaporitic deposits

Denitrification in riparian wetlands plays a major role in eliminating nitrate coming from agricultural watershed uplands before they reach river water. A new approach was developed for representing this process in the biogeochemical Riverstrahler model, using a single adjustable parameter representing the potential denitrification rate of wetland soils. Applied to the case of three watersheds with contrasting size, land-use and hydro-climatic regime, namely the Seine and the Loir rivers (France) and the Red River (Vietnam), this new model is able to capture the general level of nitrate concentrations as well as their seasonal variations everywhere over the drainage network. The nitrogen budgets calculated from the results show that riparian denitrification eliminates between 10 and 50% of the diffuse sources of nitrogen into the hydrosystem coming from soil nitrate leaching.     

Structure of a lectin with antitumoral properties in king bolete (Boletus edulis) mushrooms

A novel lectin has been isolated from the fruiting bodies of the common edible mushroom Boletus edulis (king bolete, penny bun, porcino or cep) by affinity chromatography on a chitin column. We propose for the lectin the name BEL (B. edulis lectin). BEL inhibits selectively the proliferation of several malignant cell lines and binds the neoplastic cell-specific T-antigen disaccharide, Galβ1-3GalNAc. The lectin was structurally characterized: the molecule is a homotetramer and the 142-amino acid sequence of the chains was determined. The protein belongs to the saline-soluble family of mushroom fruiting body-specific lectins. BEL was also crystallized and its three-dimensional structure was determined by X-ray diffraction to 1.15 ? resolution. The structure is similar to that of Agaricus bisporus lectin. Using the appropriate co-crystals, the interactions of BEL with specific mono- and disaccharides were also studied by X-ray diffraction. The six structures of carbohydrate complexes reported here provide details of the interactions of the ligands with the lectin and shed light on the selectivity of the two distinct binding sites present in each protomer.     

A Kazal prolyl endopeptidase inhibitor isolated from the skin of Phyllomedusa sauvagii.

Searching for bioactive peptides, we analyzed acidic extracts of Phyllomedusa sauvagii skin and found two new proteins, PSKP-1 and PSKP-2, of 6.7 and 6.6 kDa, respectively, which, by sequence homology, belong to the Kazal family of serine protease inhibitors. PSKP-1 and PSKP-2 exhibit the unprecedented feature of having proline at P(1) and P(2) positions. A gene encoding PSKP-1 was synthesized and expressed in Escherichia coli. Recombinant PSKP-1 was purified from inclusion bodies, oxidatively refolded to the native state, and characterized by chemical, hydrodynamic and optical studies. PSKP-1 shows inhibitory activity against a serum prolyl endopeptidase, but is unable to inhibit trypsin, chymotrypsin, V8 protease, or proteinase K. In addition, PSKP-1 can be rendered active against trypsin by active-site site-specific mutagenesis, has bactericidal activity, and induces agglutination of red cells at micromolar concentrations. PSKP-1 might protect P. sauvagii teguments from microbial invasion, by acting as an inhibitor of an as-yet unidentified prolyl endopeptidase or directly as a microbicidal compound.     

Vulnerability of European freshwater catchments to climate change

Climate change is expected to exacerbate the current threats to freshwater ecosystems, yet multifaceted studies on the potential impacts of climate change on freshwater biodiversity at scales that inform management planning are lacking. The aim of this study was to fill this void through the development of a novel framework for assessing climate change vulnerability tailored to freshwater ecosystems. The three dimensions of climate change vulnerability are as follows: (i) exposure to climate change, (ii) sensitivity to altered environmental conditions and (iii) resilience potential. Our vulnerability framework includes 1685 freshwater species of plants, fishes, molluscs, odonates, amphibians, crayfish and turtles alongside key features within and between catchments, such as topography and connectivity. Several methodologies were used to combine these dimensions across a variety of future climate change models and scenarios. The resulting indices were overlaid to assess the vulnerability of European freshwater ecosystems at the catchment scale (18 783 catchments). The Balkan Lakes Ohrid and Prespa and Mediterranean islands emerge as most vulnerable to climate change. For the 2030s, we showed a consensus among the applied methods whereby up to 573 lake and river catchments are highly vulnerable to climate change. The anthropogenic disruption of hydrological habitat connectivity by dams is the major factor reducing climate change resilience. A gap analysis demonstrated that the current European protected area network covers <25% of the most vulnerable catchments. Practical steps need to be taken to ensure the persistence of freshwater biodiversity under climate change. Priority should be placed on enhancing stakeholder cooperation at the major basin scale towards preventing further degradation of freshwater ecosystems and maintaining connectivity among catchments. The catchments identified as most vulnerable to climate change provide preliminary targets for development of climate change conservation management and mitigation strategies.     

Foliar cuticle of Ruflorinia orlandoi nov. sp. (Pteridospermophyta) from the Lower Cretaceous of Patagonia

Foliar cuticle of a new species of Ruflorinia, R. orlandoi Carrizo et Del Fueyo, from the Lower Cretaceous Springhill Formation in Santa Cruz province, Argentina, is herein described with light and electronic (scanning and transmission) microscopy. The fronds of R. orlandoi nov. sp. are bipinnate and imparipinnate with a conspicuous main rachis bearing alternate to sub-opposite pinnae. Cuticular striations and hairs are present in both epidermises whereas stomata are only on the abaxial cuticle. Stomata have several papillate subsidiary cells and the guard cells are sunken. Ultrastructurally the adaxial and abaxial cuticles are composed of three and two cuticular layers, respectively. The cuticular characters here described are interpreted as a response to a possible adaptation to a wet climate as well as to the fluctuating environment produced by the gradual transition from fluvial to an estuarine and marine setting that characterizes the Springhill Formation. The discovery of this new species allows expanding the previous knowledge of the paleofloristic composition of the Springhill Formation with the addition of the first pteridospermous megafossil described for this formation. Moreover, the record of Ruflorinia orlandoi nov. sp. in the Springhill Formation highlights the importance of the Caytoniales during the Cretaceous in Patagonia.