Lysophosphatidylethanolamine is – in contrast to – choline – generated under in vivo conditions exclusively by phospholipase A2 but not by hypochlorous acid

Inflammatory liver diseases are associated with oxidative stress mediated particularly by neutrophilic granulocytes. At inflammatory loci, hypochlorous acid (HOCl) is generated by myeloperoxidase. HOCl reacts with a large variety of molecules and induces (among other reactions) the formation of lysophosphatidylcholine (LPC) from polyunsaturated phosphatidylcholines (PC).As liver tissue contains huge amounts of polyunsaturated PC species enhanced LPC concentrations are detectable under these conditions. However, human liver contains also major amounts of polyunsaturated phosphatidylethanolamine (PE). It is so far widely unknown, if PE oxidation by HOCl leads to the generation of LPE in a similar way as observed in the case of PC. Using MALDI-TOF mass spectrometry (MS) and ³¹P NMR spectroscopy, LPC generation from unsaturated PC could be verified in the presence of HOCl. In contrast, unsaturated PE led exclusively to chlorohydrins and other oxidation products but not to LPE.Although these data were obtained with a quite simple model system, it is obvious that LPC is a much more suitable biomarker of oxidative stress than LPE: LPC is more readily generated and also more sensitively detectable by means of mass spectrometry and other spectroscopic methods. Nevertheless, it will also be shown that the nitrile of LPE is also generated. However, this compound is exclusively detectable as negative ion.     

Aquaporins of the PIP2 class are required for efficient anther dehiscence in tobacco

Several processes during sexual reproduction in higher plants involve the movement of water between cells or tissues. Before flower anthesis, anther and pollen dehydration takes place before the release of mature pollen at dehiscence. Aquaporins represent a class of proteins that mediates the movement of water over cellular membranes. Aquaporins of the plasmamembrane PIP2 family are expressed in tobacco (Nicotiana tabacum) anthers and may therefore be involved in the movement of water in this organ. To gain more insight into the role these proteins may play in this process, we have analyzed their localization using immunolocalizations and generated plants displaying RNA interference of PIP2 aquaporins. Our results indicate that PIP2 protein expression is modulated during anther development. Furthermore, in tobacco PIP2 RNA interference plants, anther dehydration was slower, and dehiscence occurred later when compared with control plants. Together, our results suggest that aquaporins of the PIP2 class are required for efficient anther dehydration prior to dehiscence.     

The reaction between phosphatidylethanolamines and HOCl investigated by TLC: fading of the dye primuline is induced by dichloramines

Phosphatidylethanolamines (PEs) and phosphatidylglycerols (PGs) are abundant lipid constituents of the membranes of Escherichia coli. The reaction between these lipids and hypochlorous acid (HOCl), an important constituent of disinfectants, was investigated by combined thin-layer chromatography (TLC), mass spectrometry (MS), UV and fluorescence spectroscopy. Primuline is a common dye in lipid research that binds non-covalently to lipids and allows, thus, the direct evaluation of TLC plates by MS. However, primuline staining of the products between PE and HOCl is accompanied by fading of the dye. This only holds if acidic but not alkaline conditions are applied. Using a combination of TLC, UV and fluorescence spectroscopy, it will be shown that dichloramines of PE are responsible for the observed primuline fading. Since dichloramines are slowly converted under alkaline conditions into the nitriles that lack the characteristic UV properties of dichloramines, fading is not observed under alkaline conditions.     

Late Jurassic (Kimmeridgian) larger benthic Foraminifera from Santiago Coatepec, SE Puebla, Mexico

A micropaleontologic study was carried out from samples collected along a section that crops out in the Santiago Coatepec Stream, located in the southeast of the state of Puebla, Mexico. The sedimentary sequence begins with a reddish conglomerate. Above, thick and thin layers of grey-greenish sandstones that continue in fine-grained, calcareous sandstones, and, finally, in limestones. The reddish conglomerate may represent a continental environment, and the marine transgression began with the sandstone deposit that contains a marine association of Invertebrates such as Trigonids (Myophorella sp.), and other Mollusks such as Trichites sp., Ostreids and Gastropods, Echinoderms, and Sponges as Cladocoropsis mirabilis. This sequence also provides a rich assemblage of larger Foraminifera as well as Algae, which is reported for the first time in this site. The larger agglutinated Foraminiferal assemblage is composed of Alveosepta jaccardi, Pseudocyclammina lituus, Everticyclammina virguliana, Rectocyclammina chouberti, Choffatella cf. Ch. tingitana, Mesoendothyra croatica, Nautiloculina oolithica, Freixialina planispiralis, Audienusina fourcadei, Placopsilina sp., Pseudocyclammina sp., Meandrospira sp. and Lenticulina sp. All those taxa were adapted to special paleoecological conditions, such as a continuous terrigenous input. The Algae are Marinella lugeoni, Pseudoepimastopora jurassica, Permocalculus sp., and Halimeda sp. The stratigraphic distribution of the larger benthic Foraminifera allow us to propose a Kimmeridgian age for the studied sequence. The opening of the Atlantic Ocean permitted the colonization of its margins by the larger Foraminifera during this time. The data provided by the larger Foraminifera, the Algae, and the lithology may suggest an internal platform environment of warm shallow water. This foraminiferal association is constituted by cosmopolitan species which are frequent in the Tethyan Realm.     

Identification of a resistance gene Rpi-dlc1 to Phytophthora infestans in European accessions of Solanum dulcamara

Initial screening of 14 Solanum dulcamara accessions enabled the identification of individuals resistant and susceptible to Phytophthora infestans. Crosses between contrasting genotypes resulted in three F₂–BC₁ populations segregating for resistance to late blight in a laboratory assay and under field conditions. Genetic profiling of one of these populations using 128 AFLP primers generated three markers linked to the resistant phenotype. Blast analysis of the sequenced markers resulted in a plausible gene position on the distal end of the long arm of chromosome 9 that could be confirmed by CAPS markers. Thus, we describe a first resistant gene, named Rpi-dlc1, from S. dulcamara, a Solanum species native to Europe. In addition, one population was tested for broadness of resistance responses using a set of seven additional P. infestans isolates, varying in virulence. This indicated the possible presence of additional Rpi genes.