Autres contributions pour la connaissance de la végétation de la Hesse : les communautés des pleustophytes

Als Beitrag zur Kenntnis hessischer Pflanzengesellschaften werden 9 Vegetationsaufnahmen von Pleustophyten-Gesellschaften der Klasse Lemnetea minoris mitgeteilt, die auf „Pflanzensoziologischen Sonntagsexkursionen“ in den Jahren 1985 bis 1998 erstellt wurden. Die in Hessen vorkommenden Pflanzengesellschaften dieser Klasse werden im Hinblick auf pflanzensoziologisch-syntaxonomische Aspekte, Ökologie, Verbreitung und Gefährdung charakterisiert.Pleustophyte communities of the Lemnetea minoris class in Hesse are characterised with respect to their phytosociology, ecology, endangerment, and conservation with 9 relevés made between 1985 and 1998 during “phytosociological Sunday excursions”. The plant communities of this class in Hesse are characterised with respect to their phytosociology, ecology, endangerment, and conservation.9 relevés des communautés des pleustophytes de la classe Lemnetea minoris sont communiqués comme contribution á la connaissance de la végétation de Hesse. Les relevés ont été faits lors des „Pflanzensoziologische Sonntagsexkursionen (excursions phytosociologiques dominicales)“ au cours des années 1985 à 1998. Les communautés sont caractérisées par rapport aux divers aspects suivants: sociologie, syntaxonomie, écologie, menace de disparition et conservation

The ethnographic method: The origin and basis of a multitechnical approach

In this article, I present a reflection on ethnography as a method composed of a variety of techniques for conducting social research. General information is given on its origin and links with anthropological research. By questioning the classical-normative notion of the ethnographic method and using the distinction between method, methodology and technique, I offer a concept which links ethnographic research to a strategic process in which the researcher acts to connect his or her experience and knowledge on methods with creativity and personal commitment. In the course of this process, ethnography achieves scientific rigor in that it permits the emergence of the principles of creativity, system, transparency, and empirical reference, which in my opinion are the key principles in the general definition of the method. © 2010 FQS.Este artículo presenta una reflexión que revela a la etnografía como un método que integra diversas técnicas de investigación social. Se brinda información general acerca de su origen y vinculación con la investigación antropológica. Cuestionando la noción clásica-normativa del método etnográfico y estableciendo la distinción entre método, metodología y técnica, se ofrece una concepción que liga la investigación etnográfica a un proceso estratégico en el cual el investigador actúa conectando experiencia y conocimiento acerca del método, con creatividad y compromiso personal. En dicho proceso, la etnografía alcanza rigor científico en tanto permite la emergencia de los principios de creatividad, sistematicidad, transparencia y referencia empírica, siendo estos principios clave en la definición general de método

Weitere Vorkommen von Impatiens capensis in Hessen

Neue hessische Fundorte von Impatiens capensis aus dem Taunus und dessen Vorland sowie aus der Rheinebene werden berichtet. Die insbesondere im Schwarzbach-System zahlreichen Fundorte werden beschrieben und in einer Verbreitungskarte dargestellt.New Hessian stations of Impatiens capensis in the Taunus mountains as well as their foothills and in the Rhine valley are reported on. The stations which are particularly numerous in the Schwarzbach system, are described and demonstrated on a distribution map

Systemic acquired resistance

Plants can be induced to switch on defense reactions to a broad range of pathogens as a result of prior exposure to pathogens or to various chemicals or physical stress. Induced resistance is expressed locally, at the site of the infection or systemically, at sites remotely located from the initial infection. Upon recognition of the initial stimulus by the plant, a signal transduction pathway is set in motion, that includes intra and intercellular signals, and results in the activation of defense mechanisms, mostly by expression of new genes. This brief review will focus on some of the recent advances in the understanding of systemic acquired resistance and on the role played by salicylic acid in this proces

Distinguishing Direct from Indirect Interactions in Oscillatory Networks with Multiple Time Scales

Peer reviewedPublisher PD

Coherence and indistinguishability of highly pure single photons from non-resonantly and resonantly excited telecom C-band quantum dots

In the present work, the effect of resonant pumping schemes in improving the photon coherence is investigated on InAs/InGaAs/GaAs quantum dots emitting in the telecom C-band. The linewidths of transitions of multiple exemplary quantum dots are determined under above-band pumping and resonance fluorescence via Fourier-transform spectroscopy and resonance scans, respectively. The average linewidth is reduced from $9.74\,\mathrm{GHz}$ in above-band excitation to $3.50\,\mathrm{GHz}$ in resonance fluorescence underlining its superior coherence properties. Furthermore, the feasibility of coherent state preparation with a fidelity of $49.2\,\%$ is demonstrated, constituting a step towards on-demand generation of coherent, single C-band photons from quantum dots. Finally, two-photon excitation of the biexciton is investigated as a resonant pumping scheme. A deconvoluted single-photon purity value of $g^{(2)}_{\mathrm{HBT}}(0)=0.072\pm 0.104$ and a degree of indistinguishability of $V_{\mathrm{HOM}}=0.894\pm0.109$ are determined for the biexciton transition. This represents an important step towards fulfilling the prerequisites for quantum communication applications like quantum repeater schemes at telecom wavelength

Localization and expression of EDS5H a homologue of the SA transporter EDS5

An important signal transduction pathway in plant defence depends on the accumulation of salicylic acid (SA). SA is produced in chloroplasts and the multidrug and toxin extrusion transporter ENHANCED DISEASE SUSCEPTIBILITY5 (EDS5; At4g39030) is necessary for the accumulation of SA after pathogen and abiotic stress. EDS5 is localized at the chloroplast and functions in transporting SA from the chloroplast to the cytoplasm. EDS5 has a homologue called EDS5H (EDS5 HOMOLOGUE; At2g21340) but its relationship to EDS5 has not been described and its function is not known. Results: EDS5H exhibits about 72 % similarity and 59 % identity to EDS5. In contrast to EDS5 that is induced after pathogen inoculation, EDS5H was constitutively expressed in all green tissues, independently of pathogen infection. Both transporters are located at the envelope of the chloroplast, the compartment of SA biosynthesis. EDS5H is not involved with the accumulation of SA after inoculation with a pathogen or exposure to UV stress. A phylogenetic analysis supports the hypothesis that EDS5H may be an H+/organic acid antiporter like EDS5. Conclusions: The data based on genetic and molecular studies indicate that EDS5H despite its homology to EDS5 does not contribute to pathogen-induced SA accumulation like EDS5. EDS5H most likely transports related substances such as for example phenolic acids, but unlikely SA

Genetic evidence that expression of NahG modifies defence pathways independent of salicylic acid biosynthesis in the Arabidopsis–Pseudomonas syringae pv. tomato interaction

The salicylic acid (SA)-induction deficient (sid) mutants of Arabidopsis, eds5 and sid2 accumulate normal amounts of camalexin after inoculation with Pseudomonas syringae pv. tomato (Pst), while transgenic NahG plants expressing an SA hydroxylase that degrades SA have reduced levels of camalexin and exhibit a higher susceptibility to different pathogens compared to the sid mutants. SID2 encodes an isochorismate synthase necessary for the synthesis of SA. NahG was shown to act epistatically to the sid mutant phenotype regarding accumulation of camalexin after inoculation with Pst in eds5NahG and sid2NahG plants. The effect of the pad4 mutation on the sid mutant phenotype was furthermore tested in eds5pad4 and sid2pad4 double mutants, and it was demonstrated that PAD4 acts epistatically to EDS5 and SID2 regarding the production of camalexin after inoculation with Pst. NahG plants and pad4 mutants were also found to produce less ethylene (ET) after infection with Pst in comparison to the wild type (WT) and sid mutants. Both PAD4 and NahG acted epistatically to SID regarding the Pst-dependent production of ET that was found to be necessary for the accumulation of camalexin. Early production of jasmonic acid (JA) 12 h after inoculation with Pst/avrRpt2 was absent in all plants expressing NahG compared to the other mutants tested here. These genetic studies unravel pleiotropic changes in defence signalling of NahG plants that are unlikely to result from their low SA content. This adds unexpected difficulties in the interpretation of earlier findings based solely on NahG plants