@phdthesis{Koenig2016, author = {K{\"o}nig, Sebastian}, title = {Spatially selective visual attention in Drosophila melanogaster}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-134452}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2016}, abstract = {Finding the right behavior at the right time is one of the major tasks of brains. In a natural scenery there is often an abundance of stimuli present and the brain has to separate the relevant from the irrelevant ones. Selective visual attention (SVA) is a property of higher visual systems that achieves this separation, as it allows to '[…] focus on one source of sensory input to the exclusion of others' (Luck and Mangun, 1996). There are probably several forms of SVA depending upon the criteria used for the separation, such as salience, color, location in space, novelty, or motion. Many studies have investigated SVA in humans and non-human primates. However, complex functions like attention were initially not expected to be already implemented in the brains of simple organisms like Drosophila. After a first demonstration of selective attention in the fly (Wolf and Heisenberg, 1980), it took some time until other studies included attentional mechanisms in their argumentation to explain certain behaviors of Drosophila. However, their definition and characterization of attention differed and often was ambiguous. Here, one particular form, spatially selective visual attention in the fly Drosophila is investigated. It has been shown earlier that the fly spontaneously may restrict its behavioral responses in stationary flight to the visual stimuli on one side of the visual field. On the basis of experiments of Sareen et al., (2011) it has been conjectured that the fly has a focus of attention (FoA) and that the fly responds to the visual stimuli within this area of the visual field. Whether the FoA is the adequate concept for this spatial property of SVA in the fly needs to be further discussed and is a subject also of the present study. At this stage, the concept will be used in the description of the new results expanding the characterization of SVA. This study continued the investigation of SVA during tethered flight with variable but controlled visual input and an automated primary data evaluation. This standardized paradigm allowed for analysis of wild-type behavior as well as for a comparison of several mutant and pharmacologically manipulated strains to the wild-type. Some properties of human SVA like the occurrence of externally as well as internally caused shifts of attention were found in Drosophila and it could be shown, that SVA in the fly can be externally guided and has an attention span. Additionally, a neurotransmitter and proteins, which play a significant role in SVA were discovered. Based on this, the genetic tools available for Drosophila provided the means to a first examination of cells and circuits involved in SVA. Finally, the free walk behavior of flies that had been shown to have compromised SVA was characterized. The results suggested that the observed phenotypes of SVA were not behavior specific. Covert shifts of the FoA were investigated. The FoA can be externally guided by visual cues to one or the other side of the visual field and even after the cue has disappeared it remains there for <4s. An intriguing finding of this study is the fact, that the quality of the cue determines whether it is attractive or repellent. For example a cue can be changed from being repellent (negative) to being attractive (positive) by changing its oscillation amplitude from 4° to 2°. Testing the effectiveness of cues in the upper and lower visual field separately, revealed that the perception of a cue by the fly is not exclusively based on a sum of its specifications. Because positive cueing did not have an after-effect in each of the two half-fields alone, but did so if the cue was shown in both, the fly seems to evaluate the cue for each combination of parameters specifically. Whether this evaluation of the cue changed on a trial-to-trial basis or if the cue in some cases failed to shift the FoA can at this point not be determined. Looking at the responses of the fly to the displacement of a black vertical stripe showed that they can be categorized as no responses, syn-directional responses (following the direction of motion of the stripe) and anti-directional responses (in the opposite direction of the motion of the stripe). The yaw-torque patterns of the latter bared similarities with spontaneous body saccades and they most likely represented escape attempts of the fly. Syn-directional responses, however, were genuine object responses, distinguishable by a longer latency until they were elicited and a larger amplitude. These properties as well as the distribution of response polarities were not influenced by the presence or absence of a cue. When two stripes were displaced simultaneously in opposite directions the rate of no responses increased in comparison to the displacement of a single stripe. If one of the stripes was cued, both, the responses towards and away from the side of cue resembled the syn-directional responses. Significant progress was made with the elucidation of the neuronal underpinnings of SVA. Ablation of the mushroom bodies (MB) demonstrated their requirement for SVA. Furthermore, it was shown that dopamine signaling has to be balanced between too much and too little. Either inhibiting the synthesis of dopamine or its re-uptake at the synapse via the dDAT impaired the flies' susceptibility to cueing. Using the Gal4/UAS system, cell specific expression or knockdown of the dDAT was used to scrutinize the role of MB sub-compartments in SVA. The αβ-lobes turned out to be necessary and sufficient to maintain SVA. The Gal4-line c708a labels only a subset of Kenyon cells (KC) within the αβ-lobes, αβposterior. These cells stand out, because of (A) the mesh-like arrangement of their fibers within the lobes and (B) the fact that unlike the other KCs they bypass the calyx and thereby the main source of olfactory input to the MBs, forming connections only in the posterior accessory calyx (Tanaka et al., 2008). This structure receives no or only marginal olfactory input, suggesting for it a role in tasks other than olfaction. This study shows their requirement in a visual task by demonstrating that they are necessary to uphold SVA. Restoring dDAT function in these approximately only 90 cells was probably insufficient to lower the dopamine concentration at the relevant synapses and hence a rescue failed. Alternatively, the processes mediating SVA at the αβ-lobes might require an interplay between all of their KCs. In conclusion, the results provide an initial point for future research to fully understand the localization of and circuitry required for SVA in the brain. In the experiments described so far, attention has been externally guided. However, flies are also able to internally shift their FoA without any cues from the outside world. In a set of 60 consecutive simultaneous displacements of two stripes, they were more likely to produce a response with the same polarity as the preceding one than a random polarity selection predicted. This suggested a dwelling of the FoA on one side of the visual field. Assuming that each response was influenced by the previous one in a way that the probability to repeat the response polarity was increased by a certain factor (dwelling factor, df), a random selection of response type including a df was computed. Implementation of the df removed the difference between observed probability of polarity repetition and the one suggested by random selection. When the interval between displacements was iteratively increased to 5s, no significant df could be detected anymore for pauses longer than 4s. In conclusion, Drosophila has an attention span of approximately 4s. Flies with a mutation in the radish gene expressed no after-effect of cueing and had a shortened attention span of about 1s. The dDAT inhibitor methylphenidate is able to rescue the first, but does not affect the latter phenotype. Probably, radish is differently involved in the two mechanisms. This study showed, that endogenous (covert) shifts of spatially selective visual attention in the fly Drosophila can be internally and externally guided. The variables determining the quality of a cue turned out to be multifaceted and a more systematic approach is needed for a better understanding of what property or feature of the cue changes the way it is evaluated by the fly. A first step has been made to demonstrate that SVA is a fundamental process and compromising it can influence the characteristics of other behaviors like walking. The existence of an attention span, the dependence of SVA on dopamine as well as the susceptibility to pharmacological manipulations, which in humans are used to treat respective diseases, point towards striking similarities between SVA in humans and Drosophila.}, subject = {Taufliege}, language = {en} } @article{KollingBackhausHofmannetal.2022, author = {Kolling, Markus and Backhaus, Joy and Hofmann, Norbert and Keß, Stefan and Krastl, Gabriel and Soliman, Sebastian and K{\"o}nig, Sarah}, title = {Students' perception of three-dimensionally printed teeth in endodontic training}, series = {European Journal of Dental Education}, volume = {26}, journal = {European Journal of Dental Education}, number = {4}, doi = {10.1111/eje.12743}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-318676}, pages = {653 -- 661}, year = {2022}, abstract = {Introduction In endodontic education, there is a need for thorough training prior to students embarking on clinical treatment. The aim of this study was to use three-dimensional printing technology to create a new model and to compare its suitability for training purposes with resin blocks and extracted teeth. Materials and Methods Multi-jet-modelling (MJM) produced the 3D model replicating a common difficulty in root-canal morphology. An evaluation study comprising 88 students was run in the sixth semester (summer 2018 and winter 2018/2019). A new questionnaire assessed students' perception of training models and educational environment. Welch's t-test analysed significant differences. Results The most pronounced differences between models were noted when rating material hardness, radiopacity, root-canal configuration and suitability for practising. Students estimated their learning outcome as greater with 3D-printed teeth compared to resin blocks. Three-dimensionally printed teeth received significantly lower ratings with regard to enthusiasm, the learning of fine motor skills and spatial awareness, when compared to human teeth (p ≤ .001). However, 3D-printed teeth were appreciated for additional benefits, such as their cleanliness, availability and standardisation of training opportunities with complex root-canal configurations. Conclusion Students preferred extracted human teeth to 3D-printed teeth with respect to their physical characteristics and training experience. However, educational advantages may compensate for the shortcomings. The new questionnaire proved both adequate and accurate to assess the models and educational environment in endodontic training. The new 3D-printed teeth enhanced the learning opportunities.}, language = {en} } @article{StepulaKoenigWangetal.2020, author = {Stepula, Elzbieta and K{\"o}nig, Matthias and Wang, Xin-Ping and Levermann, Janina and Schimming, Tobias and Kasimir-Bauer, Sabine and Schilling, Bastian and Schl{\"u}cker, Sebastian}, title = {Localization of PD-L1 on single cancer cells by iSERS microscopy with Au/Au core/satellite nanoparticles}, series = {Journal of Biophotonics}, volume = {13}, journal = {Journal of Biophotonics}, number = {3}, doi = {10.1002/jbio.201960034}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-212655}, year = {2020}, abstract = {Programmed cell death-ligand 1 (PD-L1) is an important predictive biomarker. The detection of PD-L1 can be crucial for patients with advanced cancer where the use of immunotherapy is considered. Here, we demonstrate the use of immuno-SERS microscopy (iSERS) for localizing PD-L1 on single cancer SkBr-3 cells. A central advantage of iSERS is that the disturbing autofluorescence from cells and tissues can be efficiently minimized by red to near-infrared laser excitation. In this study we employed Au/Au core/satellite nanoparticles as SERS nanotags because of their remarkable signal brightness and colloidal stability upon red laser excitation. False-color iSERS images of the positive and negative controls clearly reveal the specific localization of PD-L1 with SERS nanotag-labeled antibodies.}, language = {en} } @article{DitzelKoenigMusembietal.2022, author = {Ditzel, Pia and K{\"o}nig, Sebastian and Musembi, Peter and Peters, Marcell K.}, title = {Correlation between coral reef condition and the diversity and abundance of fishes and sea urchins on an East African coral reef}, series = {Oceans}, volume = {3}, journal = {Oceans}, number = {1}, issn = {2673-1924}, doi = {10.3390/oceans3010001}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-284503}, pages = {1 -- 14}, year = {2022}, abstract = {Coral reefs are one of the most diverse marine ecosystems, providing numerous ecosystem services. This present study investigated the relationship between coral reef condition and the diversity and abundance of fishes, on a heavily fished East African coral reef at Gazi Bay, Kenya. Underwater visual censuses were conducted on thirty 50 × 5 m belt transects to assess the abundance and diversity of fishes. In parallel, a 25-m length of each of the same transects was recorded with photo-quadrats to assess coral community structure and benthic characteristics. For statistical analyses, multi-model inference based on the Akaike Information Criterion was used to evaluate the support for potential predictor variables of coral reef and fish diversity. We found that coral genus richness was negatively correlated with the abundance of macroalgae, whereas coral cover was positively correlated with both the abundance of herbivorous invertebrates (sea urchins) and with fish family richness. Similarly, fish family richness appeared mainly correlated with coral cover and invertebrate abundance, although no correlates of fish abundance could be identified. Coral and fish diversity were very low, but it appears that, contrary to some locations on the same coast, sea urchin abundance was not high enough to be having a negative influence on coral and fish assemblages. Due to increasing threats to coral reefs, it is important to understand the relationship among the components of the coral reef ecosystem on overfished reefs such as that at Gazi Bay.}, language = {en} } @article{KoenigKraussKelleretal.2022, author = {K{\"o}nig, Sebastian and Krauss, Jochen and Keller, Alexander and Bofinger, Lukas and Steffan-Dewenter, Ingolf}, title = {Phylogenetic relatedness of food plants reveals highest insect herbivore specialization at intermediate temperatures along a broad climatic gradient}, series = {Global Change Biology}, volume = {28}, journal = {Global Change Biology}, number = {13}, doi = {10.1111/gcb.16199}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-276441}, pages = {4027 -- 4040}, year = {2022}, abstract = {The composition and richness of herbivore and plant assemblages change along climatic gradients, but knowledge about associated shifts in specialization is scarce and lacks controlling for the abundance and phylogeny of interaction partners. Thus, we aimed to test whether the specialization of phytophagous insects in insect-plant interaction networks decreases toward cold habitats as predicted by the 'altitude niche-breadth hypothesis' to forecast possible consequences of interaction rewiring under climate change. We used a non-invasive, standardized metabarcoding approach to reconstruct dietary relationships of Orthoptera species as a major insect herbivore taxon along a broad temperature gradient (~12°C) in Southern Germany. Based on Orthoptera surveys, feeding observations, collection of fecal pellets from >3,000 individuals of 54 species, and parallel vegetation surveys on 41 grassland sites, we quantified plant resource availability and its use by herbivores. Herbivore assemblages were richer in species and individuals at sites with high summer temperatures, while plant richness peaked at intermediate temperatures. Corresponding interaction networks were most specialized in warm habitats. Considering phylogenetic relationships of plant resources, however, the specialization pattern was not linear but peaked at intermediate temperatures, mediated by herbivores feeding on a narrow range of phylogenetically related resources. Our study provides empirical evidence of resource specialization of insect herbivores along a climatic gradient, demonstrating that resource phylogeny, availability, and temperature interactively shape the specialization of herbivore assemblages. Instead of low specialization levels only in cold, harsh habitats, our results suggest increased generalist feeding due to intraspecific changes and compositional differences at both ends of the microclimatic gradient. We conclude that this nonlinear change of phylogeny-based resource specialization questions predictions derived from the 'altitude-niche breadth hypothesis' and highlights the currently limited understanding of how plant-herbivore interactions will change under future climatic conditions.}, language = {en} } @article{GeigerKerstingSchlegeletal.2022, author = {Geiger, Nina and Kersting, Louise and Schlegel, Jan and Stelz, Linda and F{\"a}hr, Sofie and Diesendorf, Viktoria and Roll, Valeria and Sostmann, Marie and K{\"o}nig, Eva-Maria and Reinhard, Sebastian and Brenner, Daniela and Schneider-Schaulies, Sibylle and Sauer, Markus and Seibel, J{\"u}rgen and Bodem, Jochen}, title = {The acid ceramidase is a SARS-CoV-2 host factor}, series = {Cells}, volume = {11}, journal = {Cells}, number = {16}, issn = {2073-4409}, doi = {10.3390/cells11162532}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-286105}, year = {2022}, abstract = {SARS-CoV-2 variants such as the delta or omicron variants, with higher transmission rates, accelerated the global COVID-19 pandemic. Thus, novel therapeutic strategies need to be deployed. The inhibition of acid sphingomyelinase (ASM), interfering with viral entry by fluoxetine was reported. Here, we described the acid ceramidase as an additional target of fluoxetine. To discover these effects, we synthesized an ASM-independent fluoxetine derivative, AKS466. High-resolution SARS-CoV-2-RNA FISH and RTqPCR analyses demonstrate that AKS466 down-regulates viral gene expression. It is shown that SARS-CoV-2 deacidifies the lysosomal pH using the ORF3 protein. However, treatment with AKS488 or fluoxetine lowers the lysosomal pH. Our biochemical results show that AKS466 localizes to the endo-lysosomal replication compartments of infected cells, and demonstrate the enrichment of the viral genomic, minus-stranded RNA and mRNAs there. Both fluoxetine and AKS466 inhibit the acid ceramidase activity, cause endo-lysosomal ceramide elevation, and interfere with viral replication. Furthermore, Ceranib-2, a specific acid ceramidase inhibitor, reduces SARS-CoV-2 replication and, most importantly, the exogenous supplementation of C6-ceramide interferes with viral replication. These results support the hypotheses that the acid ceramidase is a SARS-CoV-2 host factor.}, language = {en} } @article{KlimmBraeuKoenigetal.2024, author = {Klimm, Fabian S. and Br{\"a}u, Markus and K{\"o}nig, Sebastian and Mandery, Klaus and Sommer, Carolin and Zhang, Jie and Krauss, Jochen}, title = {Importance of habitat area, quality and landscape context for heteropteran diversity in shrub ecotones}, series = {Landscape Ecology}, volume = {39}, journal = {Landscape Ecology}, issn = {0921-2973}, doi = {10.1007/s10980-024-01798-z}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-358106}, year = {2024}, abstract = {Context Habitat loss and degradation impose serious threats on biodiversity. However, not all habitats receive the attention commensurate with their ecological importance. Shrub ecotones (successional stages between grasslands and forests) can be highly species-diverse but are often restricted to small areas as prevalent management practices either promote open grassland or forest habitats, threatening the effective conservation of ecotone species. Objectives In this study, we assessed the importance of habitat and landscape features of shrub ecotones for the rarely studied true bugs (Heteroptera), a functionally diverse taxon that comprises highly specialized species and broad generalists. Methods True bugs were sampled with a beating tray in 118 spatially independent shrub ecotones in a region of 45,000 square kilometers in Germany. In addition to habitat area and landscape context, we used a hedge index to evaluate habitat quality. Results Shrub ecotones in open habitats harbored a greater species richness and abundance compared to shaded ones in later seral stages, and species composition differed. Richness and abundance were positively affected by increasing habitat area and quality, whereas an increase in the proportion of semi-natural habitats within 1 km only enhanced richness. While feeding and habitat specialists were more sensitive to habitat area reduction than generalists, this was not the case for weak dispersers and carnivores. Conclusions Our findings emphasize the importance of large and high-quality ecotones that form a patchy mosaic of shrubs and herbaceous plants. Such ecotones can benefit both grassland species and species depending on woody plants. Conservation authorities should balance between promoting shrubs and keeping such habitats open to maximize species diversity.}, language = {en} } @phdthesis{Koenig2024, author = {K{\"o}nig, Sebastian Thomas}, title = {Temperature-driven assembly processes of Orthoptera communities: Lessons on diversity, species traits, feeding interactions, and associated faecal microorganisms from elevational gradients in Southern Germany (Berchtesgaden Alps)}, doi = {10.25972/OPUS-35460}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-354608}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2024}, abstract = {Chapter I: Introduction Temperature is a major driver of biodiversity and abundance patterns on our planet, which becomes particularly relevant facing the entanglement of an imminent biodiversity and climate crisis. Climate shapes the composition of species assemblages either directly via abiotic filtering mechanisms or indirectly through alterations in biotic interactions. Insects - integral elements of Earth's ecosystems - are affected by climatic variation such as warming, yet responses vary among species. While species' traits, antagonistic biotic interactions, and even species' microbial mutualists may determine temperature-dependent assembly processes, the lion's share of these complex relationships remains poorly understood due to methodological constraints. Mountains, recognized as hotspots of diversity and threatened by rapidly changing climatic conditions, can serve as natural experimental settings to study the response of insect assemblages and their trophic interactions to temperature variation, instrumentalizing the high regional heterogeneity of micro- and macroclimate. With this thesis, we aim to enhance our mechanistic understanding of temperature-driven assembly processes within insect communities, exemplified by Orthoptera, that are significant herbivores in temperate mountain grassland ecosystems. Therefore, we combined field surveys of Orthoptera assemblages on grassland sites with molecular tools for foodweb reconstruction, primarily leveraging the elevational gradients offered by the complex topography within the Berchtesgaden Alpine region (Bavaria, Germany) as surrogate for temperature variation (space-for-time substitution approach). In this framework, we studied the effects of temperature variation on (1) species richness, abundance, community composition, and interspecific as well as intraspecific trait patterns, (2) ecological feeding specialisation, and (3) previously neglected links to microbial associates found in the faeces. Chapter II: Temperature-driven assembly processes Climate varies at multiple scales. Since microclimate is often overlooked, we assessed effects of local temperature deviations on species and trait compositions of insect communities along macroclimatic temperature gradients in Chapter II. Therefore, we employed joint species distribution modelling to explore how traits drive variation in the climatic niches of Orthoptera species at grassland sites characterized by contrasting micro- and macroclimatic conditions. Our findings revealed two key insights: (1) additive effects of micro- and macroclimate on the diversity, but (2) interactive effects on the abundance of several species, resulting in turnover and indicating that species possess narrower climatic niches than their elevational distributions might imply. This chapter suggests positive effects of warming on Orthoptera, but also highlights that the interplay of macro- and microclimate plays a pivotal role in structuring insect communities. Thus, it underscores the importance of considering both elements when predicting the responses of species to climate change. Additionally, this chapter revealed inter- and intraspecific effects of traits on the niches and distribution of species. Chapter III: Dietary specialisation along climatic gradients A crucial trait linked to the position of climatic niches is dietary specialisation. According to the 'altitudinal niche-breadth hypothesis', species of high-elevation habitats should be less specialized compared to their low-elevation counterparts. However, empirical evidence on shifts in specialization is scarce for generalist insect herbivores and existing studies often fail to control for the phylogeny and abundance of interaction partners. In Chapter III, we used a combination of field observations and amplicon sequencing to reconstruct dietary relationships between Orthoptera and plants along an extensive temperature gradient. We did not find close but flexible links between individual grasshopper and plant taxa in space. While interaction network specialisation increased with temperature, the corrected dietary specialisation pattern peaked at intermediate elevations on assemblage level. These nuanced findings demonstrate that (1) resource availability, (2) phylogenetic relationships, and (3) climate can affect empirical foodwebs intra- and interspecifically and, hence, the dietary specialisation of herbivorous insects. In this context, we discuss that the underlying mechanisms involved in shaping the specialisation of herbivore assemblages may switch along temperature clines. Chapter IV: Links between faecal microbe communities, feeding habits, and climate Since gut microbes affect the fitness and digestion of insects, studying their diversity could provide novel insights into specialisation patterns. However, their association with insect hosts that differ in feeding habits and specialisation has never been investigated along elevational climatic gradients. In Chapter IV, we utilized the dietary information gathered in Chapter III to characterize links between insects with distinct feeding behaviour and the microbial communities present in their faeces, using amplicon sequencing. Both, feeding and climate affected the bacterial communities. However, the large overlap of microbes at site level suggests that common bacteria are acquired from the shared feeding environment, such as the plants consumed by the insects. These findings emphasize the influence of a broader environmental context on the composition of insect gut microbial communities. Chapter V: Discussion \& Conclusions Cumulatively, the sections of this dissertation provide support for the hypothesis that climatic conditions play a role in shaping plant-herbivore systems. The detected variation of taxonomic and functional compositions contributes to our understanding of assembly processes and resulting diversity patterns within Orthoptera communities, shedding light on the mechanisms that structure their trophic interactions in diverse climates. The combined results presented suggest that a warmer climate could foster an increase of Orthoptera species richness in Central European semi-natural grasslands, also because the weak links observed between insect herbivores and plants are unlikely to limit decoupled range shifts. However, the restructuring of Orthoptera communities in response to warmer temperatures depends on species' traits such as moisture preferences or phenology. Notably, we were able to demonstrate a crucial role of microclimate for many species, partly unravelling narrower climatic niches than their elevational ranges suggest. We found evidence that not only Orthoptera community composition, specialisation, and traits varied along elevational gradients, but even microbial communities in the faeces of Orthoptera changed, which is a novel finding. This complex restructuring and reassembly of communities, coupled with the nonlinear specialisation of trophic interactions and a high diversity of associated bacteria, emphasize our currently incomplete comprehension of how ecosystems will develop under future climatic conditions, demanding caution in making simplified predictions for biodiversity change under climate warming. Since these predictions may benefit from including biotic interactions and both, micro- and macroclimate based on our findings, conservation authorities and practitioners must not neglect improving microclimatic conditions to ensure local survival of a diverse set of threatened and demanding species. In this context, mountains can play a pivotal role for biodiversity conservation since these offer heterogeneous microclimatic conditions in proximity that can be utilized by species with distinct niches.}, subject = {Heuschrecken}, language = {en} }