Fakultät Naturwissenschaften

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Characterization of the major odor-active compounds in fresh rhizomes and leaves of Houttuynia cordata by comparative aroma extract dilution analysis
(2025) Xu, Zhenli; Liu, Jing; Kreissl, Johanna; Oellig, Claudia; Vetter, Walter; Steinhaus, Martin; Frank, Stephanie; Xu, Zhenli; Leibniz Institute for Food Systems Biology at the Technical University of Munich (Leibniz-LSB@TUM), Lise-Meitner-Straße 34, 85354 Freising, Germany; (Z.X.); (J.K.); Liu, Jing; Institute of Theoretical Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany;; Kreissl, Johanna; Leibniz Institute for Food Systems Biology at the Technical University of Munich (Leibniz-LSB@TUM), Lise-Meitner-Straße 34, 85354 Freising, Germany; (Z.X.); (J.K.); Oellig, Claudia; Institute of Food Chemistry, University of Hohenheim, Garbenstraße 28, 70599 Stuttgart, Germany; (C.O.); (W.V.); Vetter, Walter; Institute of Food Chemistry, University of Hohenheim, Garbenstraße 28, 70599 Stuttgart, Germany; (C.O.); (W.V.); Steinhaus, Martin; Leibniz Institute for Food Systems Biology at the Technical University of Munich (Leibniz-LSB@TUM), Lise-Meitner-Straße 34, 85354 Freising, Germany; (Z.X.); (J.K.); Frank, Stephanie; Leibniz Institute for Food Systems Biology at the Technical University of Munich (Leibniz-LSB@TUM), Lise-Meitner-Straße 34, 85354 Freising, Germany; (Z.X.); (J.K.); Rodov, Victor
Houttuynia cordata is a culinary herb from Asia. Its edible rhizomes and leaves have a fishy aroma, the molecular background of which was unknown. A comparative aroma extract dilution analysis applied to fresh rhizomes and leaves resulted in 44 and 41 odorants, respectively, 38 of which were present with FD factors ≥1 in both samples. The odorant with the highest FD factors, whether in the rhizomes or leaves, was identified as metallic, soapy, fishy smelling 3-oxododecanal. Toward clarifying its tautomeric composition, quantum calculations suggested a predominance of the enol forms in the plant. However, the form perceived at the sniffing port during GC–O remained unclear.
Decoding the geography of natural TBEV microfoci in German: a geostatistical approach based on land-use patterns and climatological conditions
(2022) Borde, Johannes P.; Glaser, Rüdiger; Braun, Klaus; Riach, Nils; Hologa, Rafael; Kaier, Klaus; Chitimia-Dobler, Lidia; Dobler, Gerhard
Background: Tickborne-encephalitis (TBE) is a potentially life-threating neurological disease that is mainly transmitted by ticks. The goal of the present study is to analyze the potential uniform environmental patterns of the identified TBEV microfoci in Germany. The results are used to calculate probabilities for the present distribution of TBEV microfoci in Germany based on a geostatistical model. Methods: We aim to consider the specification of environmental characteristics of locations of TBEV microfoci detected in Germany using open access epidemiological, geographical and climatological data sources. We use a two-step geostatistical approach, where in a first step, the characteristics of a broad set of environmental variables between the 56 TBEV microfoci and a control or comparator set of 3575 sampling points covering Germany are compared using Fisher’s Exact Test. In the second step, we select the most important variables, which are then used in a MaxEnt distribution model to calculate a high resolution (400 × 400 m) probability map for the presence of TBEV covering the entire area of Germany. Results: The findings from the MaxEnt prediction model indicate that multi annual actual evapotranspiration (27.0%) and multi annual hot days (22.5%) have the highest contribution to our model. These two variables are followed by four additional variables with a lower, but still important, explanatory influence: Land cover classes (19.6%), multi annual minimum air temperature (14.9%), multi annual sunshine duration (9.0%), and distance to coniferous and mixed forest border (7.0%). Conclusions: Our findings are based on defined TBEV microfoci with known histories of infection and the repeated confirmation of the virus in the last years, resulting in an in-depth high-resolution model/map of TBEV microfoci in Germany. Multi annual actual evapotranspiration (27%) and multi annual hot days (22.5%) have the most explanatory power in our model. The results may be used to tailor specific regional preventive measures and investigations.
Disc mower versus bar mower: Evaluation of the direct effects of two common mowing techniques on the grassland arthropod fauna
(2025) von Berg, Lea; Frank, Jonas; Betz, Oliver; Steidle, Johannes L. M.; Böttinger, Stefan; Sann, Manuela; von Berg, Lea; Evolutionary Biology of Invertebrates, Institute for Evolution and Ecology, University of Tübingen, Tübingen, Germany; Frank, Jonas; Fundamentals of Agricultural Engineering, Institute for Agricultural Engineering, University of Hohenheim, Stuttgart, Germany; Betz, Oliver; Evolutionary Biology of Invertebrates, Institute for Evolution and Ecology, University of Tübingen, Tübingen, Germany; Steidle, Johannes L. M.; Chemical Ecology, Institute for Biology, University of Hohenheim, Stuttgart, Germany; Böttinger, Stefan; Fundamentals of Agricultural Engineering, Institute for Agricultural Engineering, University of Hohenheim, Stuttgart, Germany; Sann, Manuela; Chemical Ecology, Institute for Biology, University of Hohenheim, Stuttgart, Germany
1. In Central Europe, species‐rich grasslands are threatened by intensive agriculture with frequent mowing, contributing to the reduction of arthropods such as insects and spiders. However, comprehensive and standardised studies on the direct effects of the two most agriculturally relevant mowing techniques, e.g., double‐blade bar mower versus disc mower, are lacking. 2. In a 2‐year experiment, we have investigated the direct effect of mowing on eight abundant arthropod groups in grassland, covering two seasonal mowing events in both years, using a randomised block design. We compared (a) an unmown control, (b) a double‐blade bar mower and (c) a disc mower. 3. For most of the taxonomic groups studied, a significantly lower number of individuals was found in the experimental plots immediately after mowing, regardless of the mowing technique, compared to an unmown control. This was not the case for Orthoptera and Coleoptera, which did not show a significant reduction in the number of individuals for both mowing techniques (Orthoptera) or only for the double‐blade bar mower (Coleoptera). 4. Between both mowing techniques, no significant differences were found for all taxonomic groups investigated. 5. Synthesis and applications: Our findings suggest that mowing in general has a negative impact on abundant arthropod groups in grassland, regardless of the method used. Tractor‐driven double‐blade bar mowers do not seem to be a truly insect‐friendly alternative to a conventional disc mower. Other factors such as cutting height and mowing regimes should be seriously considered to protect spiders and insects from the negative effects of mowing. In addition, we strongly recommend the maintenance of unmown refugia. Insects and spiders that are spared by mowing can take refuge in these unmown areas to avoid subsequent harvesting and thermally unfavourable conditions that arise on mown areas. Further, unmown refugia are basic habitat structures for a subsequent recolonisation of mown areas once the flora has recovered.
Echinococcus multilocularis and other taeniid metacestodes of muskrats in Luxembourg: prevalence, risk factors, parasite reproduction, and genetic diversity
(2022) Martini, Matilde; Dumendiak, Sonja; Gagliardo, Anna; Ragazzini, Francesco; La Rosa, Letizia; Giunchi, Dimitri; Thielen, Frank; Romig, Thomas; Massolo, Alessandro; Wassermann, Marion
Muskrats (Ondatra zibethicus) are competent intermediate hosts for Echinococcus multilocularis, are frequently infected with this zoonotic cestode, and have even been proposed as a target species to monitor endemicity levels of this parasite. However, their contribution to maintaining the parasitic lifecycle is still unclear. To obtain data on infection frequency and reproductive potential, 280 muskrats from the Grand Duchy of Luxembourg were examined for cestode larvae in the years 2013–2017. Based on morphological and molecular identification, Echinococcus multilocularis was found at a prevalence of 14.6%. Other metacestodes were Hydatigera kamiyai, with a prevalence of 45.7%, Taenia martis with 8.9%, Taenia polyacantha with 5.0%, and Versteria mustelae, which was found in 0.7% of all muskrats. More than 80% of E. multilocularis-infected muskrats contained fertile metacestodes with a mean number of >300,000 (and up to 1,609,816) protoscoleces, which is by far the highest reproductive potential known from any intermediate host species in Europe. Temporal analysis of E. multilocularis prevalence within the study period (and in comparison with earlier data) strongly indicates a robust increase in the studied area. Host age seemed to be an important risk factor for infection, as well as co-infections with Hydatigera kamiyai. A preference for the right medial lobe of the liver as the location of E. multilocularis metacestode was observed. Intraspecific genetic variation among 89 discrete E. multilocularis metacestodes was non-existent based on 300–1590 bp sections of cox1. This is a stark contrast to H. kamiyai, of which nine haplotypes were found on a short 318 bp section of cox1, resulting in genetic diversity in the small country of Luxembourg at a similar level than previously reported from large stretches of Europe and northern Asia.
The emergence of ecotypes in a parasitoid wasp: a case of incipient sympatric speciation in Hymenoptera?
(2021) Malec, Pawel; Weber, Justus; Böhmer, Robin; Fiebig, Marc; Meinert, Denise; Rein, Carolin; Reinisch, Ronja; Henrich, Maik; Polyvas, Viktoria; Pollmann, Marie; von Berg, Lea; König, Christian; Steidle, Johannes L. M.
Background: To understand which reproductive barriers initiate speciation is a major question in evolutionary research. Despite their high species numbers and specific biology, there are only few studies on speciation in Hymenoptera. This study aims to identify very early reproductive barriers in a local, sympatric population of Nasonia vitripennis (Walker 1836), a hymenopterous parasitoid of fly pupae. We studied ecological barriers, sexual barriers, and the reduction in F1-female offspring as a postmating barrier, as well as the population structure using microsatellites. Results: We found considerable inbreeding within female strains and a population structure with either three or five subpopulation clusters defined by microsatellites. In addition, there are two ecotypes, one parasitizing fly pupae in bird nests and the other on carrion. The nest ecotype is mainly formed from one of the microsatellite clusters, the two or four remaining microsatellite clusters form the carrion ecotype. There was slight sexual isolation and a reduction in F1-female offspring between inbreeding strains from the same microsatellite clusters and the same ecotypes. Strains from different microsatellite clusters are separated by a reduction in F1-female offspring. Ecotypes are separated only by ecological barriers. Conclusions: This is the first demonstration of very early reproductive barriers within a sympatric population of Hymenoptera. It demonstrates that sexual and premating barriers can precede ecological separation. This indicates the complexity of ecotype formation and highlights the general need for more studies within homogenous populations for the identification of the earliest barriers in the speciation process.
Hitze als Schlüssel zur Aufklärung der Lysogenie beim SPß-Phagen
(2025) Kohm, Katharina; Kohm, Katharina; Institut Biologie, Universität Hohenheim, Garbenstraße 30, D-70599, Stuttgart, Deutschland
Integrative description of Temnothorax siculus sp. n.: a new ant species from Sicily, Italy (Hymenoptera, Formicidae)
(2025) Schifani, Enrico; Alicata, Antonio; Prebus, Matthew M.; Csősz, Sándor; Schifani, Enrico; Department of Chemistry, Environmental Sustainability, and Life Sciences, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy; Alicata, Antonio; Department of Biological, Geological and Environmental Sciences, University of Catania, Via Androne 81, 95124 Catania, Italy;; Prebus, Matthew M.; Social Insect Research Group, School of Life Sciences, Arizona State University, 550 E Orange St., Tempe, AZ 85281, USA;; Csősz, Sándor; HUN-REN-ELTE-MTM Integrative Ecology Research Group, Pázmány Péter ave 1/C, 1117 Budapest, Hungary; Fernández, Fernando; Guerrero, Roberto José
The mostly Holarctic genus Temnothorax (Hymenoptera, Formicidae) is the most diverse ant genus in temperate regions. The Mediterranean, a biodiversity hotspot of rare ant species, hosts over 150 Temnothorax taxa, including several short-range endemics. Over the last few years, phylogenomic reconstructions and integrative taxonomy have significantly improved the understanding of global Temnothorax diversity, but much taxonomic work is still needed in the Mediterranean region. Here, we present the integrative description of a new species of the genus, discovered in the central Mediterranean island of Sicily: Temnothorax siculus sp. n. is defined and compared to congeneric species integrating morphometrics and phylogenomics. It is a ground-nesting, lowland species, of which workers were regularly observed foraging on bushes and small trees. In the global phylogeny, covering all the main lineages of the region, it belongs to the Palearctic clade and is related to the tuberum and unifasciatus complexes. Morphological separation from other Sicilian Temnothorax species can generally be achieved on qualitative characters, but we also provide morphometric discriminant functions to separate it from T. apenninicus and especially T. unifasciatus . Temnothorax siculus has been rarely collected but appears to be widespread in Sicily, and may occur in neighboring regions.
The low mutational flexibility of the EPSP synthase in Bacillus subtilis is due to a higher demand for shikimate pathway intermediates
(2023) Schwedt, Inge; Schöne, Kerstin; Eckert, Maike; Pizzinato, Manon; Winkler, Laura; Knotkova, Barbora; Richts, Björn; Hau, Jann-Louis; Steuber, Julia; Mireles, Raul; Noda‐Garcia, Lianet; Fritz, Günter; Mittelstädt, Carolin; Hertel, Robert; Commichau, Fabian M.
Glyphosate (GS) inhibits the 5-enolpyruvyl-shikimate-3-phosphate (EPSP) synthase that is required for aromatic amino acid, folate and quinone biosynthesis in Bacillus subtilis and Escherichia coli. The inhibition of the EPSP synthase by GS depletes the cell of these metabolites, resulting in cell death. Here, we show that like the laboratory B. subtilis strains also environmental and undomesticated isolates adapt to GS by reducing herbicide uptake. Although B. subtilis possesses a GS-insensitive EPSP synthase, the enzyme is strongly inhibited by GS in the native environment. Moreover, the B. subtilis EPSP synthase mutant was only viable in rich medium containing menaquinone, indicating that the bacteria require a catalytically efficient EPSP synthase under nutrient-poor conditions. The dependency of B. subtilis on the EPSP synthase probably limits its evolvability. In contrast, E. coli rapidly acquires GS resistance by target modification. However, the evolution of a GS-resistant EPSP synthase under non-selective growth conditions indicates that GS resistance causes fitness costs. Therefore, in both model organisms, the proper function of the EPSP synthase is critical for the cellular viability. This study also revealed that the uptake systems for folate precursors, phenylalanine and tyrosine need to be identified and characterized in B. subtilis.
Morphological and molecular identification of sarcocystis arctica in captive cheetahs (Acinonyx jubatus) in China helps clarify phylogenetic relationships with Sarcocystis caninum and Sarcocystis felis
(2025) Liao, Zhe; Zhu, Niuping; Yang, Yurong; Deng, Shuangsheng; Jäkel, Thomas; Hu, Junjie; Liao, Zhe; Yunnan Key Laboratory for Plateau Mountain Ecology, Restoration of Degraded Environments, School of Ecology and Environmental Sciences, Yunnan University, Kunming 650091, China;; Zhu, Niuping; College of Veterinary Medicine, Henan Agricultural University, Zhengzhou 450046, China; (N.Z.); (Y.Y.); Yang, Yurong; College of Veterinary Medicine, Henan Agricultural University, Zhengzhou 450046, China; (N.Z.); (Y.Y.); Deng, Shuangsheng; Joint Laboratory of Virology & Immunity, School of Biological Sciences, Yunnan University, Kunming 650091, China;; Jäkel, Thomas; Institute of Biology, Department of Parasitology, University of Hohenheim, 70599 Stuttgart, Germany; Hu, Junjie; Yunnan Key Laboratory for Plateau Mountain Ecology, Restoration of Degraded Environments, School of Ecology and Environmental Sciences, Yunnan University, Kunming 650091, China;; Salvarani, Felipe M.; Domingues, Sheyla Farhayldes Souza; Da Silveira, Júlia Angélica Gonçalves
To date, only one case is known where protozoan parasites of the genus Sarcocystis were found to infect cheetahs ( Acinonyx jubatus ); the cysts in the musculature were morphologically identified as S. felis . Here, we characterized sarcocysts by morphological and molecular methods that were observed in cheetahs who died in zoos in China. Only one type of sarcocyst was present in two of six cheetahs. By light microscopy, the sarcocyst wall was striated, 1.4–2.1 μm thick. Ultrastructurally, the wall had irregular-shaped, small villar protrusions, resembling wall type 9c, similar to those of S. arctica , S. caninum , and S. felis . The samples shared their highest molecular identity values with those of S. arctica and S. caninum : 99.9–100% and 99.8–100% (18S rRNA), 99.5% and 99.3–99.5% (28S rRNA), 95.9–97.5% and 96.3–97.3% (ITS-1), and 99.6% and 99.2–99.7% ( cox 1), respectively. Compared with ITS-1 of S. felis , identities ranged between 87.5% and 88.9%. Phylogenetic reconstruction revealed that the newly sequenced Sarcocystis clustered with S. arctica and S. caninum , whereas S. felis (ITS-1) and S. canis (ITS-1, 18S rRNA, cox 1) were sister species. Thus, we addressed the Sarcocystis species from the cheetahs as S. arctica , which is the first record of a Sarcocystis species believed to be specific for canids as intermediate hosts to infect a feline host.
Red foxes harbor two genetically distinct, spatially separated Echinococcus multilocularis clusters in Brandenburg, Germany
(2021) Herzig, Mandy; Maksimov, Pavlo; Staubach, Christoph; Romig, Thomas; Knapp, Jenny; Gottstein, Bruno; Conraths, Franz J.
Background: Alveolar echinococcosis (AE) is a clinically serious zoonosis caused by the fox tapeworm Echinococcus multilocularis. We studied the diversity and the distribution of genotypes of E. multilocularis isolated from foxes in Brandenburg, Germany, and in comparison to a hunting ground in North Rhine-Westphalia. Methods: Echinococcus multilocularis specimens from 101 foxes, 91 derived from Brandenburg and 10 derived from North Rhine-Westphalia, were examined. To detect potential mixed infections with different genotypes of E. multilocularis, five worms per fox were analyzed. For genotyping, three mitochondrial markers, namely cytochrome c oxidase subunit 1 (Cox1), NADH dehydrogenase subunit 1 (Nad1), and ATP synthase subunit 6 (ATP6), and the nuclear microsatellite marker EmsB were used. To identify nucleotide polymorphisms, the mitochondrial markers were sequenced and the data were compared, including with published sequences from other regions. EmsB fragment length profiles were determined and confirmed by Kohonen network analysis and grouping of Sammon’s nonlinear mapping with k-means clustering. The spatial distribution of genotypes was analyzed by SaTScan for the EmsB profiles found in Brandenburg. Results: With both the mitochondrial makers and the EmsB microsatellite fragment length profile analyses, mixed infections with different E. multilocularis genotypes were detected in foxes from Brandenburg and North Rhine-Westphalia. Genotyping using the mitochondrial markers showed that the examined parasite specimens belong to the European haplotype of E. multilocularis, but a detailed spatial analysis was not possible due to the limited heterogeneity of these markers in the parasite population. Four (D, E, G, and H) out of the five EmsB profiles described in Europe so far were detected in the samples from Brandenburg and North Rhine-Westphalia. The EmsB profile G was the most common. A spatial cluster of the E. multilocularis genotype with the EmsB profile G was found in northeastern Brandenburg, and a cluster of profile D was found in southern parts of this state. Conclusions: Genotyping of E. multilocularis showed that individual foxes may harbor different genotypes of the parasite. EmsB profiles allowed the identification of spatial clusters, which may help in understanding the distribution and spread of the infection in wildlife, and in relatively small endemic areas.
Soil drought sets site specific limits to stem radial growth and sap flow of Douglas-fir across Germany
(2024) Niessner, Armin; Ehekircher, Stefan; Zimmermann, Reiner; Horna, Viviana; Reichle, Daniel; Land, Alexander; Spangenberg, Göran; Hein, Sebastian; Niessner, Armin; Department of Silviculture, University of Applied Forest Sciences, Rottenburg am Neckar, Germany; Ehekircher, Stefan; Department of Silviculture, University of Applied Forest Sciences, Rottenburg am Neckar, Germany; Zimmermann, Reiner; Ecological Botanical Gardens ÖBG, University of Bayreuth, Bayreuth, Germany; Horna, Viviana; Department of Biogeochemical Processes, Max Planck Institute for Biogeochemistry, Jena, Germany; Reichle, Daniel; Institute of Biology, University of Hohenheim, Stuttgart, Germany; Land, Alexander; Department of Silviculture, University of Applied Forest Sciences, Rottenburg am Neckar, Germany; Spangenberg, Göran; Department of Silviculture, University of Applied Forest Sciences, Rottenburg am Neckar, Germany; Hein, Sebastian; Department of Silviculture, University of Applied Forest Sciences, Rottenburg am Neckar, Germany
Introduction: Soil drought during summer in Central Europe has become more frequent and severe over the last decades. European forests are suffering increasing damage, particularly Norway spruce. Douglas-fir ( Pseudotsuga menziesii (Mirbel) Franco), a non-native tree species, is considered as a promising alternative to build drought-resilient forests. The main goal of this study was to investigate the intraannual radial stem growth and sap flow performance of Douglas-fir along a precipitation gradient across Germany under severe drought. Material and methods: Sap flow and stem radial changes of up to ten trees each at four sites with different precipitation regimes were measured in combination with volumetric soil water content during the growing season of 2022. Measurements of stem radial changes were used to calculate the trees’ stem water deficit, a proxy for tree water status and drought stress. Results: The severe summer drought of 2022 led to an early growth cessation and a significant reduction in daily sap flow at all four sites monitored. We could identify a site-specific threshold in soil water availability ranging between 21.7 and 29.6% of relative extractable water (REW) under which stem water reserves cannot be replenished and thereby inhibiting radial growth. We could also demonstrate that at this threshold, sap flow is heavily reduced to between 43.5 and 53.3%, and for a REW below 50%, sap flow linearly decreases by 1.1–2.0% per 1% reduction in REW. This reduction tends to follow the humidity gradient, being more pronounced at the most oceanic characterized site and suggesting an adaptation to site conditions. Even though Douglas-fir is considered to be more drought stress resistant than Norway spruce, growth and sap flow are greatly reduced by severe summer drought, which became more frequent in recent years and their frequency and intensity is likely to increase. Conclusions: Our results suggest that timber production of Douglas-fir in Central Europe will decline considerably under projected climate change, and thus pointing to site specific growth constraints for a so far promising non-native tree species in Europe.

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