Untersuchungen zur Lipoxygenase-vermittelten chemischen Verteidigung: Oxylipine aus Diatomeen und dem Moos "Physcomitrella patens"

Chemische Verteidigungsstrategien der Diatomeen (Kieselalgen) werden als neuer Aspekt der Diatomeen/Kopepoden-Interaktion diskutiert, da eine diatomeenreiche maternale Ernährung die Embyrogenese von Kopepoden inhibieren kann. Nach Zellverletzung bilden Diatomeen aus C20-/C16-Polyenfettsäuren Lipoxygenase-vermittelt alpha,beta,gamma,delta-ungesättigte Aldehyde, die als teratogene Substanzen in Laborexperimenten identifiziert wurden. Um die ökologische Relevanz dieser Oxylipine zu untersuchen, wurde eine leistungsfähige GC-MS Analytik entwickelt, die eine in situ Derivatisierung mit Pentafluorobenzylhydroxylamin sowie eine zuverlässige Quantifizierung in Freilandversuchen erlaubt. In einem kombinierten Ansatz aus klassischen Fütterungsversuchen und chemisch analytischen Messungen wurde das Küstengewässer vor Roscoff (Bretagne, Frankreich) beprobt, um einen Überblick des Nahrungseinflusses auf die Eiablage und den Schlupferfolg von Calanus helgolandicus zu erhalten. Des weiteren wurde die Lipoxygenasechemie im Rahmen einer Reihenuntersuchungen an 51 Diatomeenarten und exemplarisch an dem genetisch zugänglichen Modelorganismus Physcomitrella patens untersucht

Untersuchungen zur Lipoxygenase-vermittelten chemischen Verteidigung: Oxylipine aus Diatomeen und dem Moos "Physcomitrella patens"

Chemische Verteidigungsstrategien der Diatomeen (Kieselalgen) werden als neuer Aspekt der Diatomeen/Kopepoden-Interaktion diskutiert, da eine diatomeenreiche maternale Ernährung die Embyrogenese von Kopepoden inhibieren kann. Nach Zellverletzung bilden Diatomeen aus C20-/C16-Polyenfettsäuren Lipoxygenase-vermittelt alpha,beta,gamma,delta-ungesättigte Aldehyde, die als teratogene Substanzen in Laborexperimenten identifiziert wurden. Um die ökologische Relevanz dieser Oxylipine zu untersuchen, wurde eine leistungsfähige GC-MS Analytik entwickelt, die eine in situ Derivatisierung mit Pentafluorobenzylhydroxylamin sowie eine zuverlässige Quantifizierung in Freilandversuchen erlaubt. In einem kombinierten Ansatz aus klassischen Fütterungsversuchen und chemisch analytischen Messungen wurde das Küstengewässer vor Roscoff (Bretagne, Frankreich) beprobt, um einen Überblick des Nahrungseinflusses auf die Eiablage und den Schlupferfolg von Calanus helgolandicus zu erhalten. Des weiteren wurde die Lipoxygenasechemie im Rahmen einer Reihenuntersuchungen an 51 Diatomeenarten und exemplarisch an dem genetisch zugänglichen Modelorganismus Physcomitrella patens untersucht

Cultivating the macroalgal holobiont: effects of integrated multi-trophic aquaculture on the microbiome of Ulva rigida (chlorophyta)

Ulva is a ubiquitous macroalgal genus of commercial interest. Integrated Multi-Trophic Aquaculture (IMTA) systems promise large-scale production of macroalgae due to their high productivity and environmental sustainability. Complex host-microbiome interactions play a decisive role in macroalgal development, especially in Ulva spp. due to algal growth- and morphogenesis-promoting factors released by associated bacteria. However, our current understanding of the microbial community assembly and structure in cultivated macroalgae is scant. We aimed to determine (i) to what extent IMTA settings influence the microbiome associated with U. rigida and its rearing water, (ii) to explore the dynamics of beneficial microbes to algal growth and development under IMTA settings, and (iii) to improve current knowledge of host-microbiome interactions. We examined the diversity and taxonomic composition of the prokaryotic communities associated with wild versus IMTA-grown Ulva rigida and surrounding seawater by using 16S rRNA gene amplicon sequencing. With 3141 Amplicon Sequence Variants (ASVs), the prokaryotic richness was, overall, higher in water than in association with U. rigida. Bacterial ASVs were more abundant in aquaculture water samples than water collected from the lagoon. The beta diversity analysis revealed distinct prokaryotic communities associated with Ulva collected in both aquacultures and coastal waters. Aquaculture samples (water and algae) shared 22% of ASVs, whereas natural, coastal lagoon samples only 9%. While cultivated Ulva selected 239 (8%) host-specific ASVs, wild specimens possessed more than twice host-specific ASVs (17%). Cultivated U. rigida specimens enriched the phyla Cyanobacteria, Planctomycetes, Verrucomicrobia, and Proteobacteria. Within the Gammaproteobacteria, while Glaciecola mostly dominated the microbiome in cultivated algae, the genus Granulosicoccus characterized both Ulva microbiomes. In both wild and IMTA settings, the phylum Bacteroidetes was more abundant in the bacterioplankton than in direct association with U. rigida. However, we observed that the Saprospiraceae family within this phylum was barely present in lagoon water but very abundant in aquaculture water. Aquaculture promoted the presence of known morphogenesis-inducing bacteria in water samples. Our study suggests that IMTA significantly shaped the structure and composition of the microbial community of the rearing water and cultivated U. rigida. Detailed analysis revealed the presence of previously undetected taxa associated with Ulva, possessing potentially unknown functional traits.European Union (EU)642575; German Research Foundation (DFG) CRC 1127 ChemBioSys;COST Action "Phycomorph" FA1406info:eu-repo/semantics/publishedVersio

Microbiome-Dependent Adaptation of Seaweeds Under Environmental Stresses: A Perspective

The microbiome of macroalgae facilitates their adaptation to environmental stress. As bacteria release algal growth and morphogenesis promoting factors (AGMPFs), which are necessary for the healthy development of macroalgae, bacteria play a crucial role in stress adaptation of bacterial-algal interactions. To better understand the level of macroalgal dependence on the microbiome under various stress factors such as light, temperature, salt, or micropollutants, we propose a reductionist analysis of a tripartite model system consisting of the axenic green alga Ulva (Chlorophyta) re-infected with two essential bacteria. This analysis will allow us to decipher the stress response of each symbiont within this cross-kingdom interaction. The paper highlights studies on possible survival strategies embedded in cross-kingdom interactions that govern the stress adaptation, including general features of metabolic pathways in the macroalgal host or more specific features such as alterations in the composition and/or diversity of bacterial assemblages within the microbiome community. Additionally, we present some preliminary results regarding the effect of recently isolated bacteria from the Potter Cove, King George Island (Isla 25 de Mayo) in Antarctica, on the model system Ulva mutabilis Føyn purified gametes. The results indicate that cold-adapted bacteria release AGMPFs, inducing cell differentiation, and cell division in purified cultures. We propose that microbiome engineering can be used to increase the adaptability of macroalgae to stressful situations with implications for, e.g., the sustainable management of (land-based) aquaculture systems

Bisphenol A: Quantification in Complex Matrices and Removal by Anaerobic Sludges

The endocrine disruptor bisphenol A (BPA) is one of the most commonly found micropollutants in the environment. However, the biodegradation of BPA under anaerobic (methanogenic) conditions is still an understudied process in wastewater treatment systems. The current study thus addresses the need for a simple and user-friendly analytical method for the rapid and accurate quantification of BPA in complex matrices such as digested and co-digester sludges. We established a microwave-assisted extraction method, followed by derivatization and gas chromatography–mass spectrometry to quantify BPA by comparing it with a deuterated internal standard. The BPA removal capabilities of three digester sludges and three co-digester sludges were examined under mesophilic methanogenic conditions in biogas plants. The endogenous BPA concentration (dry weight) ranged from 1596 to 10,973 µg kg −1 in digested sewage sludges, and from below the limit of quantification to 9069 µg kg −1 in co-digester sludges. When BPA was added to the sludges, the removal capabilities ranged from not significant to 50% after 21 days of incubation. Biogas production was unaffected by the addition of BPA (228 µg kg −1 ) to the aqueous sludge. The study demonstrated that BPA could be removed under anaerobic conditions in accustomed inoculates. The findings have far-reaching implications for understanding BPA persistence and detoxification under anaerobic conditions

Stereoselective Total Synthesis of (−)‐Thallusin for Bioactivity Profiling

Chemical mediators are key compounds for controlling symbiotic interactions in the environment. Here, we disclose a fully stereoselective total synthesis of the algae differentiation factor (−)‐thallusin that utilizes sophisticated 6‐ endo ‐cyclization chemistry and effective late‐stage sp 2 –sp 2 ‐couplings using non‐toxic reagents. An EC 50 of 4.8 pM was determined by quantitative phenotype profiling in the green seaweed Ulva mutabilis (Chlorophyte), underscoring this potent mediator‘s enormous, pan‐species bioactivity produced by symbiotic bacteria. SAR investigations indicate that (−)‐thallusin triggers at least two different pathways in Ulva that may be separated by chemical editing of the mediator compound structure

Regulation of gametogenesis and zoosporogenesis in Ulva linza (Chlorophyta) : comparison with Ulva mutabilis and potential for laboratory culture

Green Ulvophyte macroalgae represent attractive model systems for understanding growth, development and evolution. They are untapped resources for food, fuel and high-value compounds, but can also form nuisance blooms. To fully analyse green seaweed morphogenesis, controlled laboratory-based culture of these organisms is required. To date, only a single Ulvophyte species, Ulva mutabilis Føyn, has been manipulated to complete its whole life cycle in laboratory culture and to grow continuously under axenic conditions. Such cultures are essential to address multiple key questions in Ulva development and in algal-bacterial interactions. Here we show that another Ulva species, U. linza, with a broad geographical distribution, has the potential to be grown in axenic culture similarly to U. mutabilis. Ulva linza can be reliably induced to sporulate (form gametes and zoospores) in the laboratory, by cutting the relevant thallus tissue into small pieces and removing extracellular inhibitors (sporulation and swarming inhibitors). The germ cells work as an ideal feed stock for standardized algae cultures.The requirement of U. linza for bacterial signals to induce its normal morphology (particularly of the rhizoids) appears to have a species-specific component. The axenic cultures of these two species pave the way for future comparative studies of algal-microbial interactions

Effect of inelastic ion collisions on low-gain avalanche detectors explained by an A_Si-Si_i-defect mode

The acceptor removal phenomenon (ARP), which hampers the functionality of low-gain avalanche detectors (LGAD), is discussed in frame of the A_Si-Si_i-defect model. The assumption of fast diffusion of interstitial silicon is shown to be superfluous for the explanation of the B_Si-Si_i-defect formation under irradiation, particular at very low temperatures. The experimentally observed properties of the ARP are explained by the donor properties of the B_Si-Si_i-defect in its ground state. Additionally, low temperature photoluminescence spectra are reported for quenched boron doped silicon showing so far unidentified PL lines, which change due to well-known light-induced degradation (LID) treatments