Origin of spatial genetic structure in an expanding oak population

Spatial genetic structure (SGS) results from the interplay of several demographical processes that are difficult to tease apart. In this study, we explore the specific effects of seed and pollen dispersal and of early postdispersal mortality on the SGS of a seedling cohort (N = 786) recruiting within and around an expanding pedunculate oak (Quercus robur) stand. Using data on dispersal (derived from parentage analysis) and mortality (monitored in the field through two growing seasons), we decompose the overall SGS of the cohort into its components by contrasting the SGS of dispersed (i.e. growing away from their mother tree) vs. nondispersed (i.e. growing beneath their mother tree) and initial vs. surviving seedlings. Patterns differ strongly between nondispersed and dispersed seedlings. Nondispersed seedlings are largely responsible for the positive kinship values observed at short distances in the studied population, whereas dispersed seedlings determine the overall SGS at distances beyond c. 30 m. The paternal alleles of nondispersed seedlings show weak yet significantly positive kinships up to c. 15 m, indicating some limitations in pollen flow that should further promote pedigree structures at short distances. Seedling mortality does not alter SGS, except for a slight increase in the nondispersed group. Field data reveal that mortality in this group is negatively density‐dependent, probably because of small‐scale variation in light conditions. Finally, we observe a remarkable similarity between the SGS of the dispersed seedlings and that of the adults, which probably reflects dispersal processes during the initial expansion of the population. Overall, this study demonstrates that incorporating individual‐level complementary information into analyses can greatly improve the detail and confidence of ecological inferences drawn from SGS.     

Construction of a two-dimensional gel electrophoresis protein database for the Nicotiana tabacum cv. Bright Yellow-2 cell suspension culture

Using two-dimensional gel electrophoresis (2-DE) and electrospray-tandem mass spectrometry (ESI-MS/MS), we have started the proteome analysis of the cell line Nicotiana tabacum cv. Bright Yellow-2 (tobacco BY-2). The BY-2 cell suspension culture is widely used as a model system to study the growth and development of plant cells. We present a protocol describing the sample preparation and 2-DE, enabling us to separate and display more than 1000 proteins from this cell culture. A reference gel was generated, using immobilized pH gradient isoelectric focusing in a linear gradient from pH 3 to 10 and 12% Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Although the tobacco genome is not sequenced yet, a range of protein spots from this reference map was identified by means of a semi-automated liquid chromatography-ESI-quadrupole time of flight-tandem MS (LC-ESI-QTOF-MS-MS) setup and cross-species matching. These data were integrated in a database, which can be accessed at http://tby2-www.uia.ac.be/tby2/. On the on-line reference map, the identified protein spots are hyperlinked to individual protein entries. Each protein entry contains all identification information, as well as links to relevant entries in other on-line databases. Comprehensive search functions are implemented. Especially for an unsequenced but widespread model organism like tobacco BY-2, such a reference database is a convenient source for protein information that brings protein identification within reach without the need for extensive MS. This publicly accessible database provides a solid basis for tobacco BY-2 proteomics in the future.     

Integration of gel-based proteome data with pProRep

pProRep is a web application integrating electrophoretic and mass spectral data from proteome analyses into a relational database. The graphical web-interface allows users to upload, analyse and share experimental proteome data. It offers researchers the possibility to query all previously analysed datasets and can visualize selected features, such as the presence of a certain set of ions in a peptide mass spectrum, on the level of the two-dimensional gel. AVAILABILITY: The pProRep package and instructions for its use can be downloaded from http://www.ptools.ua.ac.be/pProRep. The application requires a web server that runs PHP 5 (http://www.php.net) and MySQL. Some (non-essential) extensions need additional freely available libraries: details are described in the installation instructions.     

Influence of Exogenous Hormones on Somatic Embryogenesis in Hevea brasiliensis

Generating somatic embryos from the inner teguments of Heveaseeds is difficult. Like other ligneous plants, the rubber-treeis generally considered to be recalcitrant with regard to somaticembryogenesis. In this paper we show that when conventionallyused amounts of both 3, 4-dichlorophenoxyacetic acid (3, 4-D)and benzylaminopurine (BAP) are reduced by 2–4 times andwhen the length of exposure to these hormones is also reduced,the embryogenic capacity of calli increases without affectingcallogenesis. The germination of several embryos and plantletswas obtained. We conclude that an excess of auxin and cytokininin the medium, even of a weak auxin such as 3, 4-D, and theprolonged exposure to these hormones suppress the embryogeniccapacity of the callus. Hevea brasiliensis, rubber-tree, somatic embryogenesis, hormones     

Occurrence of aflatoxin B1 and ochratoxin A in Lebanese cultivated wheat

An extensive survey of filamentous fungi isolated from wheat grown and consumed in Lebanon and their capacity to produce aflatoxin B₁ (AFB₁) and ochratoxin A (OTA) was conducted to assess fungi potential for producing these toxins in wheat. From the 468 samples of wheat kernel, collected at preharvest stage from different locations during 2008 and 2009 cultivation seasons, 3,260 fungi strains were isolated with 49.4% belonging to Penicillium spp. and 31.2% belonging to Aspergillus spp. Penicillium spp. was detected on wheat samples with a high amount of P. verrucosum (37.0%). Among the different Aspergillus spp. isolated, A. niger aggregate was predominant and constituted 37.3%. whereas the isolation rate of A. flavus and A. ochraceus was 32.2 and 25.6%, respectively. The ability to produce OTA and AFB₁ by isolates belonging to Aspergillus spp. and Penicillium spp. was analyzed by high performance liquid chromatography with fluorescence detector (HPLC-FLD). It was found that 57.0% of Penicillium spp. and 80% of A. ochraceus isolates tested produced OTA, respectively, at maximum concentrations of 53 and 65 μg/g CYA. As for the aflatoxinogenic ability, 45.3% of A. flavus produced AFB₁, with maximum concentration of 40 μg/g CYA. A total of 156 wheat samples were analyzed for the levels of OTA and AFB₁ by HPLC-FLD. The results showed that 23.7% were contaminated with OTA, at a concentration higher than 3 μg/kg and 35.2% of these samples were contaminated with AFB₁ at concentration higher than 2 μg/kg. The risks originating from toxin levels in wheat produced in Lebanon should be monitored to prevent their harmful effects on public health.     

Synthesis and Biological Evaluation of 3-Chloro-4-(D-Ribofuranosyl)-Pyridine and 3-(D-Ribofuranosyl)-2- Pyridone

Abstract

Condensation of 2-fluoro-3-lithio pyridine and 3-chloro-4-lithio pyridine with 2,4:3,5-di-O-benzylidene-alde-hydo-D-ribose gives the corresponding D-allo- and D-altro-addition products. These were converted into the corresponding mesylates and cyclized to the ribofuranosyl nucleosides with an overall yield of 60–70 %. Both nucleosides did not show any inhibitory effect on L-₁₂₁₀-cells.     

Energy and greenhouse gas balance of bioenergy production from poplar and willow: a review

Short‐rotation woody crops (SRWC) such as poplar and willow are an important source of renewable energy. They can be converted into electricity and/or heat using conventional or modern biomass technologies. In recent years many studies have examined the energy and greenhouse gas (GHG) balance of bioenergy production from poplar and willow using various approaches. The outcomes of these studies have, however, generated controversy among scientists, policy makers, and the society. This paper reviews 26 studies on energy and GHG balance of bioenergy production from poplar and willow published between 1990 and 2009. The data published in the reviewed literature gave energy ratios (ER) between 13 and 79 for the cradle‐to‐farm gate and between 3 and 16 for cradle‐to‐plant assessments, whereas the intensity of GHG emissions ranged from 0.6 to 10.6 g CO₂ Eq MJ_biomass^?1 and 39 to 132 g CO₂ Eq kWh^?1. These values vary substantially among the reviewed studies depending on the system boundaries and methodological assumptions. The lack of transparency hampers meaningful comparisons among studies. Although specific numerical results differ, our review revealed a general consensus on two points: SRWC yielded 14.1–85.9 times more energy than coal (ER_coal～0.9) per unit of fossil energy input, and GHG emissions were 9–161 times lower than those of coal (GHG_coal～96.8). To help to reduce the substantial variability in results, this review suggests a standardization of the assumptions about methodological issues. Likewise, the development of a widely accepted framework toward a reliable analysis of energy in bioenergy production systems is most needed.     

P2Y12 receptor signalling towards PKB proceeds through IGF-I receptor cross-talk and requires activation of Src, Pyk2 and Rap1

Previously it was shown that stimulation of the P2Y12 receptor activates PKB signalling in C6 glioma cells [K. Van Kolen and H. Slegers, J. Neurochem. 89, 442.]. In the present study, the mechanisms involved in this response were further elucidated. In cells transfected with the Gbetagamma-scavenger beta-ARK1/GRK2 or Rap1GAPII, stimulation with 2MeSADP failed to enhance PKB phosphorylation demonstrating that the signalling proceeds through Gbetagamma-subunits and Rap1. Moreover, Rap1-GTP pull-down assays revealed that P2Y12 receptor stimulation induced a rapid activation of Rap1. Treatment of cells with the Ca2+ chelator BAPTA-AM and inhibition of Src and PLD2 with PP2 or 1-butanol, respectively, abrogated P2Y12 receptor-mediated activation of Rap1 and PKB. In addition inhibition of PKCzeta decreased basal and 2MeSADP-stimulated phosphorylation of PKB indicating a role for this PKC isoform in PKB signalling. Although the increased PKB phosphorylation was abolished in the presence of the IGF-I receptor tyrosine kinase inhibitor AG 1024, 2MeSADP did not significantly increase receptor phosphorylation. Nevertheless, phosphorylation of a 120 kDa IGF-I receptor-associated protein was observed. The latter protein was identified by MALDI-TOF/TOF-MS as the proline-rich tyrosine kinase 2 (Pyk2) that co-operates with Src in a PLD2-dependent manner. Consistent with the signalling towards Rap1 and PKB, activation of Pyk2 was abrogated by Ca2+ chelation, inhibition of PLD2 and IGF-I receptor tyrosine kinase activity. In conclusion, the data reveal a novel type of cross-talk between P2Y12 and IGF-I receptors that proceeds through Gbetagamma-, Ca2+-and PLD2-dependent activation of the Pyk2/Src pathway resulting in GTP-loading of Rap1 required for an increased PKB phosphorylation.