Food preferences explain distribution of the two marine gastropods Hydrobia ulvae and Littorina littorea

Im Rahmen des Meeresbiologischen Praktikums in der Forschungsstation Kristineberg (Schweden) im Sommer 2004 haben wir untersucht, ob die marinen Gastropodenarten Hydrobia ulvae und Littorina littorea Futterpräferenzen aufweisen. In Laborversuchen wurden beiden Arten unterschiedliche Kombinationen der Pflanzen Fucus vesiculosus, Ceramium rubrum und Zostera marina angeboten. H. ulvae zeigte eine deutliche Präferenz für C. rubrum. Bei L. littorea konnte keine Präferenz festgestellt werden. Quantitative Beobachtungen im Freiland ergaben, daß verschiedene Größenklassen von L. littorea unterschiedliche Pflanzen bevorzugen. Adulte L. littorea traten auf F. vesiculosus, und F. serratus auf. Juvenile Exemplare von L. littorea hingegen fanden sich auf Laminaria saccharina, Sargassum muticum, Ceramium rubrum, Enteromorpha flexuosa und Zostera marina.Peer Reviewe

European Atlas of Natural Radiation

Natural ionizing radiation is considered as the largest contributor to the collective effective dose received by the world population. The human population is continuously exposed to ionizing radiation from several natural sources that can be classified into two broad categories: high-energy cosmic rays incident on the Earth’s atmosphere and releasing secondary radiation (cosmic contribution); and radioactive nuclides generated during the formation of the Earth and still present in the Earth’s crust (terrestrial contribution). Terrestrial radioactivity is mostly produced by the uranium and thorium radioactive families together with potassium. In most circumstances, radon, a noble gas produced in the radioactive decay of uranium, is the most important contributor to the total dose. This Atlas aims to present the current state of knowledge of natural radioactivity, by giving general background information, and describing its various sources. This reference material is complemented by a collection of maps of Europe displaying the levels of natural radioactivity caused by different sources. It is a compilation of contributions and reviews received from more than 80 experts in their field: they come from universities, research centres, national and European authorities and international organizations. This Atlas provides reference material and makes harmonized datasets available to the scientific community and national competent authorities. In parallel, this Atlas may serve as a tool for the public to: • familiarize itself with natural radioactivity; • be informed about the levels of natural radioactivity caused by different sources; • have a more balanced view of the annual dose received by the world population, to which natural radioactivity is the largest contributor; • and make direct comparisons between doses from natural sources of ionizing radiation and those from man-made (artificial) ones, hence to better understand the latter.JRC.G.10-Knowledge for Nuclear Security and Safet

European Atlas of Natural Radiation

Natural ionizing radiation is considered as the largest contributor to the collective effective dose received by the world population. The human population is continuously exposed to ionizing radiation from several natural sources that can be classified into two broad categories: high-energy cosmic rays incident on the Earth’s atmosphere and releasing secondary radiation (cosmic contribution); and radioactive nuclides generated during the formation of the Earth and still present in the Earth’s crust (terrestrial contribution). Terrestrial radioactivity is mostly produced by the uranium and thorium radioactive families together with potassium. In most circumstances, radon, a noble gas produced in the radioactive decay of uranium, is the most important contributor to the total dose.This Atlas aims to present the current state of knowledge of natural radioactivity, by giving general background information, and describing its various sources. This reference material is complemented by a collection of maps of Europe displaying the levels of natural radioactivity caused by different sources. It is a compilation of contributions and reviews received from more than 80 experts in their field: they come from universities, research centres, national and European authorities and international organizations.This Atlas provides reference material and makes harmonized datasets available to the scientific community and national competent authorities. In parallel, this Atlas may serve as a tool for the public to: • familiarize itself with natural radioactivity;• be informed about the levels of natural radioactivity caused by different sources;• have a more balanced view of the annual dose received by the world population, to which natural radioactivity is the largest contributor;• and make direct comparisons between doses from natural sources of ionizing radiation and those from man-made (artificial) ones, hence to better understand the latter.Additional information at: https://remon.jrc.ec.europa.eu/About/Atlas-of-Natural-Radiatio

Hyphenunterstützte Transportprozesse der Allelochemikalie Juglon im Boden

Foreword IV Acknowledgements V List of figures VII List of tables VIII Chapter I: General Introduction 9 Chapter II: Soil hypha mediated movement of allelochemicals: arbuscular mycorrhizae extend the bioactive zone of juglone 21 Chapter III: Arbuscular mycorrhizal fungal hyphae enhance transport of the allelochemical juglone in natural soil 48 Chapter V: General Discussion 68 Chapter VI: Summary/Zusammenfassung 73 Contribution to the publications 81 Curriculum vitae 82Allelopathy is in general a biological phenomenon by which plants release one or more naturally occurring chemical compounds into the environment and therefore influence neighboring plants negatively (Rice, 1974). Since the whole subject area of allelopathy is quite complex and multifactorial, the relevance of allelopathic processes in ecology, especially their role in plant-plant interactions, has been controversially discussed and frequently called into question (Macias et al., 2007; Callaway et al., 2008). This complexity issues arise on the one hand from the fact that allelochemicals have to be present in the soil in adequate amounts to be effective (Choesin and Boerner, 1991). On the other hand, many other factors potentially influence the effectiveness of an allelopathic compound, like physical and chemical properties, as well as the influence of soil organisms (Inderjit, 2001, 2005). One of the most important functional groups in soil are mycorrhizal fungi, which influence ecologically relevant processes in diverse ways (Allen, 1996) and actually seem to impact allochemical transport processes significantly with their hyphal network present in the soil. Mycorrhizal fungal hyphae play an important role in several other transport processes, like water (Egerton-Warburton et al., 2007) or nutrient transfer (He et al., 2003; Mikkelsen et al., 2008), as well as in underground signal induced plant communication (Song et al., 2010) and mycorrhizal based warning of herbivory (Babikova et al., 2013). Thus, the so-called NEBaZ model was developed, which suggests that bioactive zones of allelochemicals are extended by the presence of a mycorrhizal fungal network (Barto et al., 2011). In this present dissertation the role of arbuscular mycorrhizal fungi in transport processes of the allelochemical juglone was investigated by using a variety of different experimental approaches. Juglone has been known for several hundred years to have growth retarding effects on the surrounding vegetation; the chemical compound occurs in high amounts in the Black walnut (Juglans nigra L.) but also in other members of the Juglandaceae. Because of its toxicity, juglone was frequently the subject of allelopathic research (Crist and Sherf, 1973; Jose and Gillespie, 1998; Li et al., 2010). To be able to arrive at a generally accepted and potential ecologically relevant statement concerning the role of mycorrhizal networks in transport processes using the example of juglone, I tried to cover as broad spectrum of experimental approaches as possible. My studies reached from controlled greenhouse to field experiments lasting several weeks using variable experimental designs (RECs or mycorrhizal inoculation) with several ways of adding the allelochemical juglone (direct application of the pure chemical, leaf litter extract or leaf litter addition). Additionally, I conducted a field study for several months using the naturally occurring juglone concentration in soil for further analyses and a bioassay. The variation in the experiments should elucidate and support the general idea, that mycorrhizal networks play an important role in transport processes of juglone and emphasize the necessity to consider mycorrhizal fungal networks in further allelopathy research. The most important findings were: The growth retarding effect of juglone on phytometer plant biomass (Lycopersicon lycopersicum) was shown in all experiments in presence of mycorrhizal hyphae (manuscript I and II). The amount of naturally released juglone by Juglans regia was significantly higher (p=0.02) in those RECs connected to the surrounding hyphal network. These higher juglone amounts negatively affected root biomass of plants in a subsequent bioassay experiment (experiment 1, manuscript I). In addition, the growth inhibiting effect of juglone was shown clearly in the presence of Rhizophagus irregularis, because both the addition of juglone by using leaf litter (experiment 2, manuscript I) and especially by adding the chemical compound juglone directly (experiment 3, manuscript II) resulted in significant growth retarding effects of root biomass (p=0.01, experiment 2, manuscript I) or shoot biomass (p=0.01, experiment 3, manuscript I), if mycorrhizal fungal hyphae were present. Additionally, two more field experiments (manuscript II) confirm the notion that mycorrhizal fungal hyphae relevantly enhance the transport of juglone in soil and therefore lead to reduced growth of sensitive phytometer plants. Both the addition of a Juglans regia leaf litter extract (experiment 1, manuscript II) and the application of leaf litter (experiment 2, manuscript II) resulted in significantly reduced total biomass (p<0.001, experiment 1, manuscript II; p=0.03, experiment 2, manuscript II) in the presence of an intact hyphal connection to the surrounding mycorrhizal network. All results together show that the presence of mycorrhizal hyphae or the connection to an existing mycorrhizal network in soil influence the transport of juglone and therefore enlarge its bioactive zone. Hyphal networks can increase effectivity of allelochemicals in natural systems and hence play an essential role in chemical interaction processes, which then again impact the structure of plant communities.Allelopathie wird im Allgemeinen als ein biologisches Phänomen gesehen, bei dem Pflanzen eine oder mehrere, in ihr natürlich vorkommende chemische Verbindungen in die Umwelt abgeben, und dabei andere in der Umgebung vorkommende Pflanzen negativ beeinflussen (Rice, 1974). Der ganze Themenbereich der Allelopathie ist hochkomplex und vielschichtig, weshalb die Bedeutung allelopathischer Prozesse in der Ökologie, insbesondere ihre Rolle in Pflanzeninteraktionen, immer wieder kontrovers diskutiert und in Frage gestellt wird (Macias et al., 2007; Callaway et al., 2008). Die Komplexität kommt zum Einen dadurch zustande, dass allelopathische Verbindungen in ausreichenden Mengen im Boden vorhanden sein müssen, um wirksam zu sein (Choesin and Boerner, 1991), und zum Anderen, weil zahlreiche weitere Faktoren, unter Anderem physikalische und chemische Eigenschaften, sowie der Einfluss von Bodenorganismen, die Effektivität einer allelopathischen Substanz maßgeblich beeinflussen können (Inderjit, 2001, 2005). Eine der wichtigsten funktionellen Organismengruppen im Boden, die arbuskulären Mykorrhizapilze beeinflussen auf vielerlei Weise ökologisch bedeutsame Prozesse (Allen, 1996) und scheinen mit ihrem Hyphennetzwerk im Boden auch eine wichtige Rolle in Transportprozessen allelopathischer Substanzen zu spielen. Dadurch, dass Mykorrhizanetzwerke bei vielen anderen Transportprozessen, wie zum Beispiel beim Wasser- (Egerton-Warburton et al., 2007) und Nährstofftransport (He et al., 2003; Mikkelsen et al., 2008), sowie bei der unterirdischen, signalinduzierten Pflanzenkommunikation (Song et al., 2010) oder mykorrhizabasierten Warnung vor Herbivorie (Babikova et al., 2013) eine maßgebliche Rolle spielen, entwickelte sich das NEBaZ-Modell, das besagt, dass die bioaktive Zone allelopathischer Stoffe in Anwesenheit von Mykorrhizanetzwerken ausgeweitet werden kann (Barto et al., 2011). In der vorliegenden Doktorarbeit wurde die Rolle von arbuskulären Mykorrhizapilzen beim Transport der allelopathischen Substanz Juglon anhand unterschiedlicher Versuchsansätze untersucht. Juglon ist ein seit Jahrhunderten bekannter, allelopathisch hemmender Stoff, der in besonders großer Menge in der schwarzen Walnuss (Juglans nigra), aber auch anderen Vertretern der Familie der Juglandaceae vorkommt und aufgrund seiner lange bekannten Toxizität schon oft Gegenstand in der allelopathischen Forschung war (Crist and Sherf, 1973; Jose and Gillespie, 1998; Li et al., 2010). Um eine möglichst allgemeingültige und potentiell ökologisch relevante Aussage über die Rolle von Mykorrhizanetzwerken bei Transportprozessen am Beispiel von Juglon treffen zu können, habe ich im Rahmen meiner hier vorliegenden Arbeit versucht, ein möglichst breites Spektrum an Versuchsansätzen abzudecken. Meine Untersuchungen reichten von mehrwöchigen Gewächshaus- und Freilandexperimenten mit variierenden Designs (Verwendung von RECs oder Inokulation mit einer Pilzart) unter möglichst kontrollierten Bedingungen, bei denen die allelopathische Substanz Juglon auf verschiedene Art und Weise zugegeben wurde (direkte Zugabe der Chemikalie, Laubextrakt- oder Laubzugabe) bis zu einer mehrmonatigen Freilandstudie, bei der das Juglon schon auf natürliche Weise im Boden vorhanden war. Die Variation in den Experimenten sollte die allgemeine Idee, dass arbuskuläre Mykorrhizapilze eine wichtige, unterstützende Rolle beim Transport der Allelochemikalie Juglon spielen, stützen und die Notwendigkeit der Beachtung von Mykorrhizanetzwerken in der Allelopathieforschung bestätigen. Die wichtigsten Ergebnisse der Arbeit sind: Die wachstumshemmende Wirkung von Juglon auf die Biomasse der Phytometerpflanzen (Lycopersicon lycopersicum) wurde in allen Versuchen (Manuskript I und II) in Anwesenheit von Mykorrhizapilzen deutlich. Das unter Walnussbäumen (Juglans regia) in realistischen Mengen, auf natürlichem Wege freigesetzte Juglon war in den Versuchseinheiten signifikant mehr vorhanden (p=0.02), wenn diese mit einem Hyphennetzwerk im Boden verbunden waren. Diese größere Menge Juglon wirkte in einem darauffolgenden Bioassayexperiment hemmend auf das Wurzelwachstum der Versuchspflanzen (Experiment 1, Manuskript I). Noch deutlicher wurden die wachstumshemmenden Effekte von Juglon in Anwesenheit von Rhizophagus irregularis. Sowohl bei der Zugabe von Juglon in Form von Juglans regia-Laub (Experiment 2, Manuskript I) als auch besonders bei der direkten Applikation der allelopathischen Substanz selbst (Experiment 3, Manuskript I) war in Anwesenheit eines pilzlichen Hyphengeflechts eine signifikante Wachstumsreduktion in der Wurzelbiomasse (p=0.01, Experiment 2, Manuskript I) oder der Sproßbiomasse (p=0.01, Experiment 3, Manuskript I) zu verzeichnen. Es konnte zusätzlich in zwei weiteren Experimenten (Manuskript II), diesmal unter Freilandbedingungen, bestätigt werden, dass Mykorrhizahyphen maßgeblich den Transport von Juglon im Boden beeinflussen und zu reduziertem Wachstum bei sensitiven Phytometerpflanzen führen. Sowohl die Zugabe eines Extraktes, der aus Juglans regia-Laub hergestellt wurde (Experiment 1, Manuskript II) also auch die Zugabe von Walnusslaub (Experiment II, Manuskript II) resultierte in signifikant verminderter Biomasse (p<0.001, Experiment 1, Manuskript II, p=0.03, Experiment 2, Manuskript II), wenn eine Verbindung zum umliegenden Hyphennetzwerk im Boden gewährleistet war. Alle Ergebnisse zusammengenommen zeigen, dass das Vorhandensein des Hyphennetzes eines Mykorrhizapilzes oder die Verbindung zu einem bereits existierenden Mykorrhizanetzwerkes im Boden Einfluss auf den Transport der allelopathischen Substanz Juglon nehmen und somit die bioaktive Zone allelopathischer Substanzen erweitern können. Hyphennetzwerke können daher die Effektivität von Allelochemikalien in natürlichen Systemen verstärken und spielen somit eine wichtige Rolle in chemischen Interaktionsprozessen, die sich wiederum auf die Struktur der Pflanzengesellschaft auswirken können

Proceedings in Marine Biology

Journal of the Graduate Course of the Freie Universiät Berlin (Germany) at Kristinebergs Marina Forskningsstation (Sweden)Zeitschrift zur Kursreise der Freien Universität Berlin (Deutschland) an die Kristinebergs Marina Forskningsstation (Schweden)Peer Reviewe

Imaging of cellular oxygen via two-photon excitation of fluorescent sensor nanoparticles

Polystyrene nanoparticles (PSNPs) with an average size of 85 nm and loaded with an oxygen-quenchable luminescent ruthenium complex were used to sense and image oxygen inside cells following 2-photon excitation (2-PE). The ruthenium probe possesses a large two-photon absorption cross-section, and 2-PE is achieved by irradiation in the near infrared with commercially available fs-pulsed laser systems. The luminescence of the dye-loaded PSNPs is strongly quenched by oxygen, and Stern–Volmer plots are linear for both conventional single-photon excitation (1-PE) and for 2-PE. The particles do not show any significant cytotoxicity below a threshold concentration of 5 μg/mL and are readily taken up by mammalian cells (MCF-7), presumably via membrane mediated pathways. Thus, the PSNPs promise to be well suited to image the oxygen distribution in living cells and tissues. The 2-PE is considered to be advantageous over conventional imaging techniques because it works in the near-infrared where background absorption and luminescence of biomatter is much weaker than at excitation wavelengths below 600 nm

Data from: The extracellular domains of IgG1 and T cell-derived IL-4/IL-13 are critical for the polyclonal memory IgE response in vivo

IgE-mediated activation of mast cells and basophils contributes to protective immunity against helminths but also causes allergic responses. The development and persistence of IgE responses are poorly understood, which is in part due to the low number of IgE-producing cells. Here, we used next generation sequencing to uncover a striking overlap between the IgE and IgG1 repertoires in helminth-infected or OVA/alum-immunized wild-type BALB/c mice. The memory IgE response after secondary infection induced a strong increase of IgE+ plasma cells in spleen and lymph nodes. In contrast, germinal center B cells did not increase during secondary infection. Unexpectedly, the memory IgE response was lost in mice where the extracellular part of IgG1 had been replaced with IgE sequences. Adoptive transfer studies revealed that IgG1+ B cells were required and sufficient to constitute the memory IgE response in recipient mice. T cell-derived IL-4/IL-13 was required for the memory IgE response but not for expansion of B cells from memory mice. Together, our results reveal a close relationship between the IgE and IgG1 repertoires in vivo and demonstrate that the memory IgE response is mainly conserved at the level of memory IgG1+ B cells. Therefore, targeting the generation and survival of allergen-specific IgG1+ B cells could lead to development of new therapeutic strategies to treat chronic allergic disorders