Photobiologische, energetische und genetische Aspekte des mutualistischen Zusammenlebens von Zooxanthellen (Symbiodinium sp.) und Steinkorallen im Golf von Aqaba, Jordanien

Die Bedeutung des Beitrages der phototrophen Energiebereitstellung durch die Zooxanthellen und die Untersuchung von Mechanismen, die eine Effektivierung der autotrophen Energiebereitstellung ermöglichen wurden an vier Steinkorallenarten des nördlichen Roten Meeres (Golf von Aqaba) mit unterschiedlichen Hauptwachstumstiefen durchgeführt. Die ausgewählten Steinkorallenarten wurden trotz ihrer eindeutigen Tiefenpräferenz in Tiefen von 5 bis 40 m gefunden. In welchem Maß die Zooxanthellen der untersuchten Steinkorallenarten in der Lage sind sich an das verändernde Lichtklima anzupassen und somit der Wirtskoralle ein größere Verbreitungszone zu erschließen, wurde anhand biochemischer und photokinetischer Parameter untersucht. Mit Hilfe von enzymelektrophoretischen Untersuchungen wurde versucht Anhaltspunkte zu finden, die auf genetische Unterschiede zwischen den Symbionten aus verschiedenen Wirtsarten oder aus unterschiedlichen Tiefen hinweisen. Die Freilandbeobachtungen und Laboruntersuchungen konnten zeigen, dass trotz der eindeutigen Tiefenpräferenzen der untersuchten Steinkorallenarten, sowohl die Wirtskorallen als auch die Symbionten in der Lage sind sich an die suboptimalen Bedingungen außerhalb ihrer Hauptwachstumszonen an zu passen. Die Wirtskolonien zeigen Anpassungen hinsichtlich der Kolonieform, der Biomasse und des Energiebedarfs. Die Korallen reduzieren ihren Gewebeanteil mit der Tiefe. Die Reduzierung des Wirtsgewebes führt zu einer reduzierten Stoffwechselrate und somit zu einem geringeren Energieverbrauch. Die Verminderung der Stoffwechselrate konnte durch die tiefenabhängige Abnahme der Respiration der Kolonien gezeigt werden. Die Anpassung des Photosyntheseapparates der Zooxanthellen an die mit der Tiefe geringer werdenden Photonenflussdichten, erfolgte bei allen Arten über die Erhöhung der Peridininkonzentration und nicht wie häufig in der Literatur beschrieben über eine Erhöhung der Chl a -Konzentration. Vertikal durchgeführte Versetzungsexperimente mit M. elephantotus Kolonien konnten zeigen, dass durch die Versetzung tatsächlich nur die Peridininkonzentrationen an die Versetzungstiefen angepasst wurden. Einen Hinweis darauf, dass nicht nur die Photonenflussdichten die Anpassungsmechanismen beeinflussen, sondern weitere tiefenabhängige Faktoren eine Rolle spielen könnten, wurde durch horizontale Versetzungsexperimente mit M. elephantotus Kolonien gegeben. Wurden die Kolonien in der gleichen Tiefe von einem gut beleuchteten Standort an einen dunklen umgesetzt, so wurde die Chl a -Konzentration signifikant angehoben, während die Peridininmenge unverändert blieb. Inwieweit die beschriebenen Anpassungsmechanismen zur Steigerung der Photosyntheseleistung führen und damit die optimale Wachstumszone der Wirtskoralle erweitern kann, wurde Sauerstoffproduktionsmessungen untersucht. Die Ergebnisse weisen darauf hin, daß die Anpassungsfähigkeit der Symbionten an veränderte Umweltbedingungen, auf einer breiten physiologischen Plastizität beruht. Die Zooxanthellen der Untersuchten Arten können ihren Photosyntheseaparat über das gesamte Tiefenspektrum von 5 bis 40 m an die Umgebungsbedingungen anpassen und so die Photosyntheseleistung optimieren. Bei der Betrachtung der Anpassungsfähigkeit der Kolonien (Wirt & Symbiont) ist die Tiefenpräferenz trotz der Anpassungsfähigkeit der Gesamtsymbiose noch deutlich zu erkennen. Dies lässt die Vermutung zu, dass nicht eine besondere Zooxanthellenart, sondern der Wirtseinfluss eine maßgebliche Rolle spielt. Die Enzymelektrophoretischen Untersuchungen konnten bestätigen, dass die untersuchten Zooxanthellen über ein breites physiologisches Reaktionsmuster verfügen müssen, da für die auswertbaren Enzyme weder eindeutige Unterschiede der Zooxanthellen aus dem Gewebe von M. elephantotus und A. squarrosa Kolonien in Abhängigkeit von der Tiefe, noch eine eindeutige Wirtsspezifität für den Vergleich der symbiontischen Algen der untersuchten Steinkorallenarten zeigen. Da keine Unterschiede zwischen den Zooxanthellen von A. squarrosa und M. elephantotus gefunden wurden, die natürliche Verbreitung von A. squarrosa jedoch mehr in geringen Wassertiefen liegt und die von M. elephantotus in größeren Tiefen, ist es denkbar, daß es nicht nur die Zooxanthellen sind die, die Tiefenverbreitung der Korallen ermöglicht, sondern ebenso die Spezialanpassung der Wirtskorallenart, wie im Fall von M. elephantotus die Fähigkeit partikuläre Nahrung über Mucusnetze zu konzentrieren und aufzunehmen. Dies könnte M. elephantotus den Vorteil geben auch in größeren Tiefen zu existieren (Schlichter & Brendelberger, 1998). Das wiederum würde bedeuten, dass die möglicherweise schon vorhandenen Symbionten in den Eizellen bzw. Planulalarven der Korallen, nicht unbedingt die entscheidende Rolle spielen beim festsetzen der Polypen an einem bestimmten Standort

Potential of Core-Collapse Supernova Neutrino Detection at JUNO

JUNO is an underground neutrino observatory under construction in Jiangmen, China. It uses 20kton liquid scintillator as target, which enables it to detect supernova burst neutrinos of a large statistics for the next galactic core-collapse supernova (CCSN) and also pre-supernova neutrinos from the nearby CCSN progenitors. All flavors of supernova burst neutrinos can be detected by JUNO via several interaction channels, including inverse beta decay, elastic scattering on electron and proton, interactions on C12 nuclei, etc. This retains the possibility for JUNO to reconstruct the energy spectra of supernova burst neutrinos of all flavors. The real time monitoring systems based on FPGA and DAQ are under development in JUNO, which allow prompt alert and trigger-less data acquisition of CCSN events. The alert performances of both monitoring systems have been thoroughly studied using simulations. Moreover, once a CCSN is tagged, the system can give fast characterizations, such as directionality and light curve

Detection of the Diffuse Supernova Neutrino Background with JUNO

As an underground multi-purpose neutrino detector with 20 kton liquid scintillator, Jiangmen Underground Neutrino Observatory (JUNO) is competitive with and complementary to the water-Cherenkov detectors on the search for the diffuse supernova neutrino background (DSNB). Typical supernova models predict 2-4 events per year within the optimal observation window in the JUNO detector. The dominant background is from the neutral-current (NC) interaction of atmospheric neutrinos with 12C nuclei, which surpasses the DSNB by more than one order of magnitude. We evaluated the systematic uncertainty of NC background from the spread of a variety of data-driven models and further developed a method to determine NC background within 15\% with {\it{in}} {\it{situ}} measurements after ten years of running. Besides, the NC-like backgrounds can be effectively suppressed by the intrinsic pulse-shape discrimination (PSD) capabilities of liquid scintillators. In this talk, I will present in detail the improvements on NC background uncertainty evaluation, PSD discriminator development, and finally, the potential of DSNB sensitivity in JUNO

Factors controlling holocene reef growth: An interdisciplinary approach

This interim report deals with investigations on key factors controlling reef growth by zoophysiologists, ecologists, paleontologists and geologists. The different levels of emphasis are the coral animal and the reef community. The main study area is the Red Sea which reaches over 20°C latitude up to the northernmost margin of the global coral reef belt. Supplementary results on microborer ecology are provided from the Bahamas. The desert enclosed Red Sea, not influenced by land runoff and only minimally by anthropogenic (urban and touristic) nutrient inputs, is predestined for a study on the principal influence of light on calcification within bathymetrical and latitudinal gradients. Hence, on the level of the zooxanthellate scleractinian animal phototrophic and heterotrophic energy supply and its bearing on calcification are being measured in different coral species—in particular inPorites sp., one of the most important reef builders. The growth of 15 zooxanthellate scleractinians in the Gulf of Aqaba correlates with the annual light cycle. This correlation is observable down to 40 m depth. Other growth promoting factors seem to have less influence on coral extension. The availability of organically enriched sediments in shallow water probably yields nutritional value, in particular for filter feeding species, thus restricting their distribution to those areas. Zooxanthellae, when isolated fromMycedium elephantotus, are different in their dependence on depth in maximum rates of photosynthesis and photosynthetic efficiency (-slope). Increasing concentrations of pigments as a function of depth could be determined. Maximum rates of photosynthesis of zooxanthellae in vivo, collected at corresponding depth, have been 4 times higher. Structural and physiological adaptations improving heterotrophic and phototrophic energy intake are highlighted. Porites sp. was the subject of annual growth studies at locations extending from Aqaba in the North over the northern and southern Egyptian coast and islands, Sanganeb Atoll and Wingate reef offshore Sudan to the Gulf of Tadjoura in the Gulf of Aden (Djibouti). Mean growth rates in the shallow water zone increase with decreasing latitude and are highest at the southernmost studied reefs in the Gulf of Tadjoura. However, the observed latitutdinal growth reduction is restricted to the upper ca. 15 m of the water column. The upper limit of growth potential decreases with depth parallel to the decrease of light availability. Highest growth rates are recorded in shallow depth (10–2.9 mm yr−1). This zone reaches at Aqaba (29°30′N) to a depth of ca. 10 m. At the southern Egyptian reefs (24°30′N) this zone extends to ca. 15 m water depth. This effect is probably a result of the stronger reduction of winter light levels and water temperature in the northern regions. Compared to other oceans the decrease of growth with increasing latitude of Red SeaPorites corals is far less, and growth rates at Aqaba are the highest observed at these latttudes. On the level of the community of reef inhabitants four principal topics are addressed: The first one is the dynamics of the proportions of hermatypic and ahermatypic organisms and open space. The occurrence of stony and soft corals and the sharing of empty space in different reef sections at Aqaba and on Sanganeb Atoll were quantified. Soft corals, mainlySinularia- and xeniid species, occupy decreasing shares with depth. Among theXenia species a bathymetrical zonation pattern was detected. The next issue is the growth impeding role of soft corals and gastropod parasites and predators on scleractinians. Experimental and field observations showed xeniid soft corals to be opportunistic i.e. occupying rapidly open space rather than to attacking and outcompeting stony corals. An increasingly specialized behaviour was detected among corallivorous gastropods of the family Coralliophilidae to exploit their coral hosts. Whereas these snails are more or less sessile and depend for a long time on the surrounding host polyps the mobileDrupella cornus (Thaididae) forms feeding aggregations which denude mainly branching corals on shallow reef parts. Furthermore, the role counteracting reef growth of macro- and microbioeroders is investigated.Diadema setosum is a major destructive agent on reefs at Aqaba (not in the central Red Sea). The grazing sea urchins do not only keep potential colonization area free but also erode carbonate material (e. g. 1468 g/m2/year, 10 m depth). Demographic and bathymetric patterns in the sea urchin population are analyzed including their bearing on bioerosion of the reef. Investigations on microboring organisms in carbonate material have started in the Red Sea; initial results, however, are only available from similar studies near Lee Stocking Island, Bahamas. Three major environments have been identified based on the distribution of the different microborers. These are the intertidal environment dominated by boring cyanobacteria., reef sites from 2 to 30 m water depth dominated by a diverse assemblage of boring cyanobacteria and chlorophytes, and the deep reef slope from 100 to 300 m dominated by boring green algae and heterotrophs. The boring chlorophyte genusPhaeophila appears rapidly and dominates at sites from 2 to 30 m, but it leaves vacated borings and is replaced byOstreobium quekettii after 1 year. Different substrate types show very different rates of colonization by microborers. The greatest excavation rates (100 g/m2/3 months) occur in fine-grained limestone, while the slowest rates (0.5 g/m2/3 months) occur in calcite crystals. Molluscan shell material shows intermediate rates of excavation. Light conditions appear very important in determining the growth rate and distribution of different microborers between the sites, however, the interaction of light with other factors, such as substrate, time period of exposure, and water quality conditions may be involved

Intermediate outcomes of transcatheter pulmonary valve replacement with the Edwards Sapien 3 valve - German experience

Background: After encouraging results with the Edwards Sapien and XT valves, this study aimed to review procedural data and early outcomes for the Sapien 3 valves for transcatheter pulmonary valve replacement (TPVR). Methods: We performed a multicenter, retrospective analysis of cases who underwent a Sapien 3 TPVR between 2015 and 2017 in 7 centers in Germany with a follow-up of up to 2 years. Results: 56 patients could be enrolled (weight 58,5 ± 25,0 kg; 53% Tetralogy of Fallot, 45% native RVOT). Most procedures were two-stage procedures (82,1%) with 100% prestenting. Valve sizes were 20 mm (n = 1), 23 mm (n = 15), 26 mm (n = 27), 29 mm (n = 13). Procedural success rate was 96.4%. Two patients underwent surgical valve implantation after balloon rupture during TPVR. Follow-up data were available up to 24-month post TPVR. The rate of patients with ? moderate and severe pulmonary regurgitation decreased to 0% after TPVR, peak systolic gradient decreased from 24,2 (SD±20,9) mmHg to 7,1 mmHg (SD±5,0). There were no endocarditis, severe tricuspid valve impairment or stent fractures. Conclusions: With the Edwards Sapien 3 valve, the patient pool for TPVR can be substantially extended. Continued data collection is necessary to verify long-term results

Potential for a precision measurement of solar pppp neutrinos in the Serappis Experiment

The Serappis (SEarch for RAre PP-neutrinos In Scintillator) project aims at a precision measurement of the flux of solar $pp$ neutrinos on the few-percent level. Such a measurement will be a relevant contribution to the study of solar neutrino oscillation parameters and a sensitive test of the solar luminosity constraint. The concept of Serappis relies on a small organic liquid scintillator detector ($\sim$20 m$^3$) with excellent energy resolution ($\sim$2.5 % at 1 MeV), low internal background and sufficient shielding from surrounding radioactivity. This can be achieved by a minor upgrade of the OSIRIS facility at the site of the JUNO neutrino experiment in southern China. To go substantially beyond current accuracy levels for the $pp$ flux, an organic scintillator with ultra-low $^{14}$C levels (below $10^{-18}$) is required. The existing OSIRIS detector and JUNO infrastructure will be instrumental in identifying suitable scintillator materials, offering a unique chance for a low-budget high-precision measurement of a fundamental property of our Sun that will be otherwise hard to access

Potential for a precision measurement of solar pppp neutrinos in the Serappis Experiment

The Serappis (SEarch for RAre PP-neutrinos In Scintillator) project aims at a precision measurement of the flux of solar $pp$ neutrinos on the few-percent level. Such a measurement will be a relevant contribution to the study of solar neutrino oscillation parameters and a sensitive test of the solar luminosity constraint. The concept of Serappis relies on a small organic liquid scintillator detector ($\sim$20 m$^3$) with excellent energy resolution ($\sim$2.5 % at 1 MeV), low internal background and sufficient shielding from surrounding radioactivity. This can be achieved by a minor upgrade of the OSIRIS facility at the site of the JUNO neutrino experiment in southern China. To go substantially beyond current accuracy levels for the $pp$ flux, an organic scintillator with ultra-low $^{14}$C levels (below $10^{-18}$) is required. The existing OSIRIS detector and JUNO infrastructure will be instrumental in identifying suitable scintillator materials, offering a unique chance for a low-budget high-precision measurement of a fundamental property of our Sun that will be otherwise hard to access

Potential for a precision measurement of solar pp neutrinos in the Serappis experiment

The Serappis (SEarch for RAre PP-neutrinos In Scintillator) project aims at a precision measurement of the flux of solar pp neutrinos on the few-percent level. Such a measurement will be a relevant contribution to the study of solar neutrino oscillation parameters and a sensitive test of the equilibrium between solar energy output in neutrinos and electromagnetic radiation (solar luminosity constraint). The concept of Serappis relies on a small organic liquid scintillator detector (∼20 m$^3$) with excellent energy resolution (∼2.5% at 1 MeV), low internal background and sufficient shielding from surrounding radioactivity. This can be achieved by a minor upgrade of the OSIRIS facility at the site of the JUNO neutrino experiment in southern China. To go substantially beyond current accuracy levels for the pp flux, an organic scintillator with ultra-low $^{14}$C levels (below 10$^{−18}$) is required. The existing OSIRIS detector andJUNO infrastructure will be instrumental in identifying suitable scintillator materials, offering a unique chance for a low-budget high-precision measurement of a fundamental property of our Sun that will be otherwise hard to access