Search

Environmental and marine conservation management pose significant challenges for decision-making. These arise not only from the numerous urgent issues confronting decision-makers but also from the uncertainties in our understanding of ecosystem functions and their responses to stressors. Value of information (VoI) theory provides a framework for evaluating the impact of these uncertainties on management decisions from the perspective of the decision-maker. VoI is becoming increasingly relevant in environmental and ecosystem management. As a decision-analytic tool, VoI quantifies the advantages of acquiring additional information to enhance decision-making processes. It assists decision-makers in selecting the optimal management strategy and determining whether immediate action is necessary or if it is beneficial to delay and invest in further data collection and research. This thesis contributes to the understanding of VoI and its application to decision problems in environmental and ecosystem management.

The effects of soil disturbance caused by the European mole (Talpa europaea, LINNAEUS 1758) on microbial decomposition of organic litter, microbial biomass C and N and concentrations of nitrate and ammonium were examined based on data collected from three sample plots in the botanical garden of the University of Oldenburg, Germany. Compared to the undisturbed pasture, molehills were characterized by a warmer microclimate, higher bulk density, lower concentrations of organic C and N as well as by reduced water contents. The effects on microbial biomass C and N were negative across all sample plots. Effects on microbial decomposition of organic litter showed no clear trend with one sample plot showing a positive effect whereas others showed no effect or a negative effect. There was no statistically significant difference in concentrations of nitrate and ammonium between molehills and undisturbed pasture except for one sample plot where nitrate concentrations were reduced in molehills. It is suggested that microbial decomposition was influenced by microclimatic differences between the sample plots which were the result of differences in shading. The overall effects of shading and water content on microbial decomposition were greater than those of molehill disturbance. Effects on microbial biomass C and N were negative, likely due to the absence of a rhizosphere and reduced concentrations of organic C and N in molehills. Molehill disturbance likely has a positive effect on N-mineralization due to the destruction of soil aggregates, explaining the lack of differences between molehills and undisturbed pasture in nitrate and ammonium concentrations. Future studies should examine effects of microclimate on microbial activity in molehills in relationship to soil water content. Der Einfluss von durch den Europäischen Maulwurf (Talpa europaea, LINNAEUS 1758) hervorgerufenen Störungen auf den mikrobiellen Abbau organischer Streu, die mikrobielle Biomasse und den mineralischen S

The topographic complexity of the mouse retina, which lacks features like the fovea, has long been underestimated. However, recent evidence has revealed anatomical and functional gradients in different retinal cell types, such as bipolar and ganglion cells. Much less is known about the topographic variations in horizontal cells. These cells form large, gap junction-coupled networks and provide feedback to photoreceptors and feedforward signaling to bipolar cells, thereby creating the antagonistic receptive fields of downstream neurons. Using intracellular injections, this thesis investigated regional specializations in mouse horizontal cells and found topographic variations, for example in gap junction coupling. These variations likely result in different spatial scales of how horizontal cells provide feedback to postsynaptic cells and may underlie the different response properties previously reported for dorsal and ventral retinal ganglion cells.

Ökologische Gemeinschaften weisen aufgrund zahlreicher Wechselwirkungen regelmäßig komplexe nichtlineare Dynamiken auf. Angesichts des Klimawandels und des Verlusts der biologischen Vielfalt ist das Verständnis der anthropogenen Auswirkungen auf mikrobielle Gemeinschaften eine wichtige Herausforderung unserer Zeit. In dieser Arbeit wird ein zweigeteilter Ansatz verfolgt, um das Verständnis der Mechanismen von komplexen ökologischen Gemeinschaften zu verbessern. Diffusion maps identifizieren wichtige metabolische Nischen in einer Langzeitdatenreihe von Bakteriengemeinschaften und reduzieren damit die Dimensionalität dieses Datensatzes. Im zweiten Teil wird ein verallgemeinerter Modellierungsansatz angewandt, um die wechselseitige Ernährung in bakteriellen Gemeinschaften zu untersuchen. Insgesamt bieten diese Fortschritte bei der Datenanalyse und Modellierung Einblicke in die Mechanismen, die Zusammensetzung und die Dynamiken mikrobieller Gemeinschaften und deren Auswirkungen auf das Funktionieren von Ökosystemen

Bacteriophages, viruses infecting bacteria, have a strong influence on bacterial community structures and ecosystem functioning in the ocean. Only little is known so far about roseophages, those infecting the important and widespread Roseobacteraceae family. Here, roseophage diversity in the North Sea was investigated by isolation, cultivation and whole genome sequencing. More than 100 new roseophages infecting the ecologically relevant genera Sulfitobacter, Lentibacter, and Octadecabacter have been isolated and genome sequenced, revealing an impressive diversity. The new phages vary in genome size, morphology and lifestyle and could be assigned to eight families in the class Caudoviricetes, comprising four already existing and four newly proposed families. The majority of the new isolates belonged to one large group of highly similar, potentially species-level related Sulfitobacter phages. Host range determination against their original isolation host strains revealed a complex infectivity network. Genome analysis of these phages and of thirty whole-genome sequenced host strains revealed a high degree of microdiversity on both sides.

Retinal degeneration protein 3 (RD3), a protein involved in the trafficking of photoreceptor-specific membrane guanylate cyclases, has recently been identified in other tissue types, suggesting a potentially broader role. However, the pathophysiological role of RD3 and its specific protein targets in tissues other than the retina have not been elucidated. In this thesis, we have characterized the RD3 transcript pattern in mouse neuronal tissues and its function in the inhibition of GC-A and GC-B. Research has also shown that loss of RD3 has diagnostic and prognostic value in glioblastoma. Moreover, RD3 can cause cell cycle arrest and programmed cell death, which may impact by its protein structure mutant. These findings suggest a novel regulatory property of RD3 in hormone receptor in brain and indicate that it may serve as a good model for elucidating neuro-ophthalmologic manifestations in neurological diseases.

In the central auditory system, miR-183 cluster plays crucial roles in auditory brainstem structure development and excitatory synaptic transmission at the calyx of Held. To probe inhibitory synaptic neurotransmission, a miR-183/96 double knockout mouse model was analyzed. Immunohistochemistry revealed significant alterations in Gphn and Gabra1 expression, key regulators of inhibitory neurotransmission. However, expression of other proteins like Kcc2, Hapln4, and Gad2/65 remained unaltered. Moreover, transcriptomic analysis unveiled 34 and 116 differentially expressed genes in LSO and MNTB, respectively. Some of of these genes play vital roles in synaptic transmission and are implicated in hearing loss.These findings underscore the intricate regulatory roles of miRNAs in auditory system development and function and offer insights into potential targets for hearing-related disorders.

Forests affect the water balance and thus deep seepage rates differently depending on species composition. Here, the effect of forest conversion on deep seepage rates is investigated in pure and mixed forests of pine (Pinus sylvestris), beech (Fagus sylvatica) and Douglas fir (Pseudotsuga menziesii) at three groundwater-distant and sandy forest sites in Northwest Germany. Based on continuous meteorological, stand precipitation and soil moisture measurements between January 2019 and October 2020, deep seepage rates are modelled with the hydrological model LWF-Brook90. Compared to pure pine forests, modelled deep seepage rates do not increase in mixed forests, but strongly increase in pure beech forests. The results further indicate that tree thinning increases deep seepage rates significantly. These modelled deep seepage rates serve as a basis for an economic evaluation of groundwater recharge as an ecosystem service to promote groundwater-emphasized forest conversion.

Guanylate cyclase-activating proteins (GCAPs) are neuronal calcium sensors that activate retinal guanylate cyclases (GCs) in a Ca2+-dependent manner. GCAP5 from the retina of the zebrafish (Danio rerio) harbors a non-conserved cysteine cluster at its N-terminal. C15 and C17 prevent a Ca2+-dependent conformational change essential for a Ca2+-dependent regulation of retinal GCs. In exchange, they mediate redox-sensitive regulation. Further, GCAP5 binds ferrous iron with nanomolar affinity (Lim et al. 2017, Biochemistry 56(51): 6652-6661): Two GCAP5 molecules coordinate one ferrous iron with C15 and C17, forming an iron-sulfur cluster in a [Fe(SCys)4] complex. These unusual characteristics of GCAP5 lead to the conclusion that it might be involved in cell protection under oxidative stress conditions.

Neurons communicate via synapses—specialized structures that consist of a presynaptic terminal of one neuron and a postsynaptic terminal of another. As knowledge is emerging that mutations in molecules that regulate synaptic function underpin many neurological disorders, it is crucial to elucidate the molecular mechanisms regulating synaptic function to understand synaptic strength, plasticity, modulation, and pathology, which ultimately impact neuronal circuit output and behavior. The presynaptic calyx of Held is a large glutamatergic presynaptic terminal in the auditory brainstem, which due to its accessibility and the possibility to selectively perform molecular perturbations on it, is an ideal model to study the role of presynaptic proteins in regulating synaptic function. In this protocol, we describe the use of confocal imaging and three-dimensional reconstruction of the calyx of Held to assess alterations in gross morphology following molecular perturbation. Using viral-vector delivery to perform molecular perturbations at distinct developmental time points, we provide a fast and cost-effective method to investigate how presynaptic proteins regulate gross morphology such as surface area and synapse volume throughout the lifetime of a neuronal circuit.

Masking can reduce the efficiency of communication and prey and predator detection. Most underwater sounds fluctuate in amplitude, which may influence the amount of masking experienced by marine mammals. The hearing thresholds of two harbor seals for tonal sweeps (centered at 4 and 32 kHz) masked by sinusoidal amplitude modulated (SAM) Gaussian one-third octave noise bands centered around the narrow-band test sweep frequencies, were studied with a psychoacoustic technique. Masking was assessed in relation to signal duration, (500, 1000, and 2000 ms) and masker level, at eight amplitude modulation rates (1–90 Hz). Masking release (MR) due to SAM compared thresholds in modulated and unmodulated maskers. Unmodulated maskers resulted in critical ratios of 21 dB at 4 kHz and 31 dB at 32 kHz. Masked thresholds were similarly affected by SAM rate with the lowest thresholds and the largest MR being observed for SAM rates of 1 and 2 Hz at higher masker levels. MR was higher for 32-kHz maskers than for 4-kHz maskers. Increasing signal duration from 500 ms to 2000 ms had minimal effect on MR. The results are discussed with respect to MR resulting from envelope variation and the impact of noise in the environment on target signal detection.

Die Biologie kennt alle Eigenschaften des Lebendigen, aber auf die Frage »Was ist Leben?« hat sie keine eindeutige Antwort. Der Grund dafür liegt im Organischen selbst: Seine Struktur folgt zwar kausalen Naturgesetzen, ist aber nicht hinreichend durch sie zu begründen. Wir beurteilen Lebewesen analog zur Technik als zweckmäßig aufgebaut, aber zugleich wissen wir, dass sie natürlich entstanden sind. Christine Zunke analysiert den Widerspruch, Leben über ein teleologisches Prinzip zu erklären und es zugleich nicht zu tun. Mit ihrer naturphilosophischen Reflexion zeigt sie auf, wie dieser Widerspruch das Denken in eine Dialektik des Lebendigen führt – oder zur Quelle biologistischer Ideologie wird.