Entwicklung eines Bewertungsverfahrens zur erfolgreichen Anwendung einer Kalzitaufspülung für die interne Restaurierung eutropher Baggerseen in Baden-Württemberg

Zusammenfassung Laboruntersuchungen haben gezeigt, daß Kalzit grundsätzlich zur Phosphat-Fixierung und Phosphat-Retention in eutrophierten Seesedimenten geeignet ist. Freilanduntersuchungen im Kirchentellinsfurter Baggersee bei Tübingen (Epplesee) machten jedoch deutlich, daß die Barrierewirkung einer Kalzitschicht durch biologische und hydrodynamische Parameter drastisch herabgesetzt werden kann. Dies wurde in Ergebnissen von Laboruntersuchungen bestätigt, die zeigten, daß die Intaktheit der Schicht eine wesentliche Voraussetzung für die längerfristige Effizienz einer Kalzitbarriere zur Seenrestaurierung ist. Hinsichtlich der Erarbeitung objektiver Bewertungskriterien zur Nachhaltigkeit des Verfahrens wurden Laborversuche durchgeführt, um die Einflußparameter Bioturbation und Resuspension auf die Stabilität der Kalzitbarriere am Beispiel des Epplesees zu quantifizieren. Es konnte gezeigt werden, daß in einem Fall eine Kalzitbarriere mit einer Mächtigkeit von 1 cm innerhalb von drei bis vier Monaten durch die Bioturbation der Larven von Chironomus plumosus bei einer Larvendichte, die den natürlichen Verhältnissen im Baggersee entspricht, fast vollständig ins Sediment eingearbeitet wird. Auch eine höhere Kalzitauflage von 2,5 cm wurde im anderen Fall in einer etwas größeren Zeitspanne von sechs Monaten in das Oberflächensediment eingemischt. In flachen Seen besteht zusätzlich die Gefahr, daß die Kalzitschicht durch windinduzierte Wellen erodiert werden kann. Die kritischen Schubspannungen von drei potentiellen Barrierematerialien wie Socal® U1-R, Kalzitmehl und Quarzsand K12 betragen 0.16 N/m2, 0.31 N/m2 bzw. 0.32 N/m2, so daß die Auflagen z. B. im durchschnittlich 4 m tiefen Epplesee nach einer Modellrechnung erst ab kritischen Windgeschwindigkeiten von ca. 15 m/s, 31 m/s bzw. 32 m/s verdriftet werden könnten. Bei entsprechender Morphometrie (Oberfläche/Tiefen-Verhältnis) und Windexposition kann jedoch eine windinduzierte Resuspension einer Kalzitbarriere in Flachseen nicht ausgeschlossen werden. The Development of Instrumental Valuation Criteria for a Successful Application of Calcite as an Internal Restoration Method for Eutrophic Gravel-pit Lakes in Baden-Württemberg (BWC 20002) Summary Laboratory experiments showed that calcite is in principle suitable for phosphorus fixation and phosphorus retention in eutrophic lake sediments. However, field studies in the gravel-pit lake of Kirchentellinsfurt near Tübingen (Epplesee) clearly pointed to the fact that the efficiency of a calcite barrier can be dramatically reduced by biological and hydrodynamic influences. This was confirmed in laboratory tests, which showed that the completeness of the calcite layer is essential to achieve a successful lake restoration over a longer time range. In view of the elaboration of objective valuation criteria for the sustainability of the method, laboratory investigations were carried out to quantify the influence of bioturbation and resuspension on the stability of the calcite barrier in Lake Epplesee. The experiments showed that a calcite barrier of 1 cm thickness in one case was almost entirely burrowed within 3 to 4 months by the bioturbation of the larvae of Chironomus plumosus. The number of the larvae corresponded to the natural occurrence in the gravel-pit lake. Even a thicker calcite layer of 2.5 cm in the other case was nearly completely mixed into the deeper sediment in a slightly longer time period of about 6 months. Wind-generated waves can erode the calcite layer, especially in shallow lakes. Therefore, the critical shear stress of three potential barrier materials (Socal® U1-R, calcite powder and sand K12) was measured. In shallow lakes like Epplesee with a mean depth of 4 m, the calculated critical wind velocities by about 16 m/s, 31 m/s and 32 m/s exceed the critical shear stresses of the barrier materials (0.15 N/m2, 0.31 N/m2 and 0.32 N/m2, respectively) and can cause erosion of these layers. According to morphometry (ratio surface/depth) and wind exposition of shallow lakes wind-induced resuspension cannot be excluded

Impact of a Wastewater Treatment Plant Upgrade on Amphipods and Other Macroinvertebrates: Individual and Community Responses

In the present study, we investigated the efficiency of additional wastewater treatment based on powdered activated carbon and its benefit for the ecosystem of a connected river system in the catchment area of Lake Constance, Southern Germany. We focused on the overall health status of gammarids and the integrity of the macrozoobenthic community. Samples were taken up- and down-stream of a wastewater treatment plant (WWTP), as well as before and after its upgrading. The investigations showed that both sex ratio and fecundity of gammarids, as well as the macrozoobenthic community were affected by the effluent prior to the WWTP upgrade. After the upgrade, gammarids from the downstream site did not differ any longer from those collected upstream of the WWTP with respect to the investigated health parameters. Furthermore, the overall number of taxa and, particularly, the number of sensitive taxa within the macrozoobenthic community downstream of the WWTP increased considerably. Therefore, we conclude that the additional treatment with powdered activated carbon was highly efficient to improve invertebrate health and community integrity

The ribosome assembly factor Nep1 responsible for Bowen–Conradi syndrome is a pseudouridine-N1-specific methyltransferase

Nep1 (Emg1) is a highly conserved nucleolar protein with an essential function in ribosome biogenesis. A mutation in the human Nep1 homolog causes Bowen–Conradi syndrome—a severe developmental disorder. Structures of Nep1 revealed a dimer with a fold similar to the SPOUT-class of RNA-methyltransferases suggesting that Nep1 acts as a methyltransferase in ribosome biogenesis. The target for this putative methyltransferase activity has not been identified yet. We characterized the RNA-binding specificity of Methanocaldococcus jannaschii Nep1 by fluorescence- and NMR-spectroscopy as well as by yeast three-hybrid screening. Nep1 binds with high affinity to short RNA oligonucleotides corresponding to nt 910–921 of M. jannaschii 16S rRNA through a highly conserved basic surface cleft along the dimer interface. Nep1 only methylates RNAs containing a pseudouridine at a position corresponding to a previously identified hypermodified N1-methyl-N3-(3-amino-3-carboxypropyl) pseudouridine (m1acp3-Ψ) in eukaryotic 18S rRNAs. Analysis of the methylated nucleoside by MALDI-mass spectrometry, HPLC and NMR shows that the methyl group is transferred to the N1 of the pseudouridine. Thus, Nep1 is the first identified example of an N1-specific pseudouridine methyltransferase. This enzymatic activity is also conserved in human Nep1 suggesting that Nep1 is the methyltransferase in the biosynthesis of m1acp3-Ψ in eukaryotic 18S rRNAs

SchussenAktivplus: reduction of micropollutants and of potentially pathogenic bacteria for further water quality improvement of the river Schussen, a tributary of Lake Constance, Germany

The project focuses on the efficiency of combined technologies to reduce the release of micropollutants and bacteria into surface waters via sewage treatment plants of different size and via stormwater overflow basins of different types. As a model river in a highly populated catchment area, the river Schussen and, as a control, the river Argen, two tributaries of Lake Constance, Southern Germany, are under investigation in this project. The efficiency of the different cleaning technologies is monitored by a wide range of exposure and effect analyses including chemical and microbiological techniques as well as effect studies ranging from molecules to communities

The Bowen–Conradi syndrome protein Nep1 (Emg1) has a dual role in eukaryotic ribosome biogenesis, as an essential assembly factor and in the methylation of Ψ1191 in yeast 18S rRNA

The Nep1 (Emg1) SPOUT-class methyltransferase is an essential ribosome assembly factor and the human Bowen–Conradi syndrome (BCS) is caused by a specific Nep1D86G mutation. We recently showed in vitro that Methanocaldococcus jannaschii Nep1 is a sequence-specific pseudouridine-N1-methyltransferase. Here, we show that in yeast the in vivo target site for Nep1-catalyzed methylation is located within loop 35 of the 18S rRNA that contains the unique hypermodification of U1191 to 1-methyl-3-(3-amino-3-carboxypropyl)-pseudouri-dine (m1acp3Ψ). Specific 14C-methionine labelling of 18S rRNA in yeast mutants showed that Nep1 is not required for acp-modification but suggested a function in Ψ1191 methylation. ESI MS analysis of acp-modified Ψ-nucleosides in a Δnep1-mutant showed that Nep1 catalyzes the Ψ1191 methylation in vivo. Remarkably, the restored growth of a nep1-1ts mutant upon addition of S-adenosylmethionine was even observed after preventing U1191 methylation in a Δsnr35 mutant. This strongly suggests a dual Nep1 function, as Ψ1191-methyltransferase and ribosome assembly factor. Interestingly, the Nep1 methyltransferase activity is not affected upon introduction of the BCS mutation. Instead, the mutated protein shows enhanced dimerization propensity and increased affinity for its RNA-target in vitro. Furthermore, the BCS mutation prevents nucleolar accumulation of Nep1, which could be the reason for reduced growth in yeast and the Bowen-Conradi syndrome

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Fortgesetzte Untersuchungen über die geograph. Lage von Nicolajef und Modena, von Hrn. Prof. Wurm

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