Institut für Biologie

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Echinococcus multilocularis and other zoonotic helminths in red foxes (Vulpes vulpes) from a southern German hotspot for human alveolar echinococcosis
(2023) Schneider, Carina; Kratzer, Wolfgang; Binzberger, Andreas; Schlingeloff, Patrycja; Baumann, Sven; Romig, Thomas; Schmidberger, Julian
Background: We describe the spatial distribution of Echinococcus multilocularis in its main definitive host, the red fox, and the distribution of human cases of alveolar echinococcosis (AE) within a highly endemic focus in southern Germany (13.7–19.9/100,000 in 1992–2018). Human cases were unequally distributed within the endemicity focus. The purpose of the study was to test whether this is reflected in the small-scale distribution of E. multilocularis in foxes. Methods: Three areas with contrasting numbers of human cases were selected within the counties of Ravensburg and Alb-Donau, Baden-Württemberg, Germany. From 2018 to 2020, a total of 240 fox carcasses were obtained from traditional hunters in these areas. Carcasses were necropsied and examined for the presence of intestinal helminths. The statistical analysis was performed with SAS version 9.4, and the geo-mapping with QGIS version 3.16.0 Hannover. Results: The prevalence of E. multilocularis in foxes was 44/106 (41.5%) in area I (commune Leutkirch and environs), 30/59 (50.8%) in area II (commune Isny and environs), and 31/75 (41.3%) in area III (commune Ehingen and environs). From 1992 to 2018, a total of nine human cases of alveolar echinococcosis were recorded in area I, five cases were recorded in study area III, and no cases were recorded in area II. No statistically significant differences between the areas were observed ( P > 0.05) for intestinal infections with E. multilocularis , and no apparent spatial correlation with the small-scale distribution of human cases was found. Concerning other zoonotic helminths, Toxocara spp. were equally common, with prevalence of 38.7%, 47.4% and 48.0%, respectively, while the frequency of Alaria alata varied among the study areas (0.0–9.4%), probably reflecting the specific habitat requirements for the establishment of its complex life cycle. Conclusions: Echinococcus multilocularis is highly prevalent in foxes in all the studied areas. The varying number of human AE cases within these areas should therefore be caused by factors other than the intensity of parasite transmission in foxes.
Tick hazard in a Central European country: Mapping Europe’s principal tick-borne disease vector across Germany
(2025) Springer, Andrea; Lindau, Alexander; Fachet-Lehmann, Katrin; Kämmer, Daniel; Bulling, Ingrid; Knoll, Steffen; Król, Nina; Fischer, Dominik; Fischer, Luisa; Drehmann, Marco; Chitimia-Dobler, Lidia; Noll, Madeleine; Vineer, Hannah Rose; Kahl, Olaf; Pfeffer, Martin; Strube, Christina; Mackenstedt, Ute
The most common European tick species, Ixodes ricinus, is the principal vector of Borrelia and tick-borne encephalitis virus and several other pathogens of public health relevance in Europe. Comprehensive data on tick abundance and the underlying ecological drivers are crucial for developing awareness and control strategies and to assess future changes in tick-borne disease risk. We aimed to provide a Germany-wide map of I. ricinus abundance to aid in disease transmission risk assessment. During 2018−2020, questing tick density was assessed at 83 sites across the whole country by drag flagging, whereby 49,344 I. ricinus nymphs and adults were collected. Relationships between climate, land cover, and monthly questing I. ricinus nymph density were explored and used to draw an abundance map. Highest tick hazard was observed in areas near the coast with mild winters and moist springs, and in mid-elevation mountain ranges, which represent popular tourist destinations. The ticks’ seasonal activity pattern was predominantly unimodal. The fact that the observed regional differences are contradictory to a previous estimation based on a combination of regional studies illustrates the need for an extensive and coordinated sampling effort to reliably estimate tick abundance at larger spatial scales. Combined with data on tick-borne pathogens, our study enables estimating the density of infected ticks and consequently the risk of acquiring an infectious tick bite. Moreover, the observed relationships with climate and land cover can help to predict future developments of tick hazard under different climate scenarios in Central Europe.
Reactivation of the tRNASer/tRNATyr gene cluster in Arabidopsis thaliana root tips
(2025) Hummel, Guillaume; Kumari, Priyanka; Hua, Chenlei; Wang, Long; Mai, Yan-Xia; Wang, Nan; Shala, Negjmedin; Kaya, Emir Can; Molinier, Jean; Wang, Jia-Wei; Liu, Chang
Plants maintain redundant tRNA genes (tDNAs) in their nuclear genomes, but the significance, regulation, and functional roles of these genes remain poorly understood. A cluster of tandemly repeated tDNAs decoding serine and tyrosine (SYY cluster) is located on Arabidopsis (Arabidopsis thaliana) chromosome 1, intersecting constitutive heterochromatin and remaining transcriptionally silenced in most tissues. The natural conditions inducing their transcription remain unknown. Here, we elucidate the tissue-specific expression pattern of this cluster during seedling establishment. Our findings reveal that SYY cluster tRNAs are primarily produced in the root cap columella and adjacent root cap cells. Transcriptional reactivation of the SYY cluster occurs in these tissues despite high DNA methylation levels. Furthermore, we demonstrate that these cells accumulate high levels of a transgenic glycoprotein rich in serine, tyrosine, and proline, and that CRISPR/Cas9 deletion of the SYY cluster alters the accumulation and stability of the glycoprotein in these specific cells. Our work provides pioneering evidence of a developmental and cell-specific expression program for a plant tDNA. We offer insights into the putative role of specialized tDNAs in enhancing glycoprotein biosynthesis in protective tissues of the meristem.
The RNF/NQR redox pumps: a versatile system for energy transduction in bacteria and archaea
(2025) Buckel, Wolfgang; Ermler, Ulrich; Vonck, Janet; Fritz, Günter; Steuber, Julia
The Na + (or H + )-translocating ferredoxin:NAD + oxidoreductase (also called RNF, rhodobacter nitrogen fixation, complex) catalyzes the oxidation of reduced ferredoxin with NAD + , hereby generating an electrochemical gradient. In the reverse reaction driven by an electrochemical gradient, RNF provides reduced ferredoxin using NADH as electron donor. RNF plays a crucial role in the metabolism of many anaerobes, such as amino acid fermenters, acetogens, or aceticlastic methanogens. The Na + -translocating NADH:quinone oxidoreductase (NQR), which has evolved from an RNF, is found in selected bacterial groups including anaerobic, marine, or pathogenic organisms. Since NQR and RNF are not related to eukaryotic respiratory complex I (NADH:quinone oxidoreductase), members of this oxidoreductase family are promising targets for novel antibiotics. RNF and NQR share a membrane-bound core complex consisting of four subunits, which represent an essential functional module for redox-driven cation transport. Several recent 3D structures of RNF and NQR in different states put forward conformational coupling of electron transfer and Na + translocation reaction steps. Based on this common principle, putative reaction mechanisms of RNF and NQR redox pumps are compared. Key points: • Electrogenic ferredoxin:NAD + oxidoreductases (RNF complexes) are found in bacteria and archaea. • The Na + -translocating NADH:quinone oxidoreductase (NQR) is evolutionary related to RNF. • The mechanism of energy conversion by RNF/NQR complexes is based on conformational coupling of electron transfer and cation transport reactions.
Diversity, ecology and response to climate change of Triassic temnospondyls: an integrative approach on global and regional scales
(2025) Moreno, Raphael; Schoch, Rainer
Temnospondyls are relatives of modern amphibians and represent a significant part of the fossil record of Triassic ecosystems. The Triassic was a period characterised by pronounced climatic and environmental changes. Due to their widespread occurrence temnospondyls offer unique insights into ecologically dynamic environments. In this dissertation, I apply an integrative approach on diverse geographic extents, including studies of global, regional and local measures and different stratigraphic scopes. Through a holistic framework of several methodologies, I aim to study the diversity and ecology of Triassic temnospondyls and their response to the changing Triassic climate. First, I present an extensive review of the global geographic and stratigraphic distribution of Triassic temnospondyls, before engaging in a detailed investigation of temnospondyl diversity within the German Triassic. Herein we identify 20 genera and 29 species of Triassic temnospondyls and advance the taxonomic identification through re-evaluations and identification of a new species occurring in the regional context of the German Triassic. Furthermore, we recognise three pronounced peaks of temnospondyl diversity coinciding with periods of enhanced ecological stability. In the second project, I employ species distribution modelling (SDM) to investigate the palaeogeographic distribution and potential dispersal routes of the temnospondyl fauna of the Central European basin and Central Pangea. I model the group response to changing environmental conditions during the Middle–Late Triassic transition, a period characterised by climatic fluctuations. Notably, this study is the first application of SDM on temnospondyls and highlights the dependency of temnospondyls on suitable abiotic conditions for their biogeographic distribution. Moreover, I quantify the changes in suitable habitat across various time slices from the Middle to Late Triassic period. Crucially, ecological resilience becomes evident as multiple clades persist through (1) phases of habitat reduction and (2) significant environmental and climatic changes. The utilisation of computational simulations on the deep time fossil record enhances our understanding of the interplay between dynamically changing climates and palaeobiological responses. The third project documents the ecological plasticity and adaptability of temnospondyls through new discoveries in depositional environments that have been previously deemed unsuitable for temnospondyl habitation. I assess and identify fragmentary remains of an unexpectedly diverse assemblage of temnospondyls in the sabkha and playa depositional environment of the Grabfeld Formation of southern Germany. The dolomitic banks that yielded some of the temnospondyl remains were deposited during brief marine ingressions from the Tethys Ocean into the Central European basin. The occurrence of sauropterygians and ostracods indicate euryhaline conditions. The identification of Metoposaurus in these layers challenges previous assumptions on the physiological tolerances of the group and further provides the stratigraphically oldest occurrence of this taxon in a global context. Furthermore, the occurrence of Plagiosternum in the same environment supports the general notion for the preferred palaeoenvironmental habitat of Plagiosternum while presenting the stratigraphically youngest occurrence of this taxon. In the last chapter, I investigate the palaeoenvironmental differences in the geographically close and coeval Middle Triassic fossil sites of Kupferzell and Vellberg-Eschenau in Baden-Württemberg, Germany. I investigate the geochemical properties in an attempt to characterise the degree of diagenetic alteration. Subsequent carbon and oxygen isotope analyses of tooth enamel of the temnospondyl Mastodonsaurus giganteus, as well as subsequent analyses of dental and skeletal bioapatite of associated fauna, reveal a substantial variation in the palaeoenvironments of both fossil localities. While both palaeoenvironments are characterised as lacustrine ecosystems, the observed isotopic differences portray Kupferzell as a more stable depositional environment with less episodic fluctuations, while the lacustrine system of Vellberg-Eschenau, especially layer E6, is depicted as more dynamic with greater seasonal and hydrological variabilities. Furthermore, the investigation of intra-tooth sample series fits the interpretation of a seasonally more dynamic setting in Vellberg-Eschenau E6. Overall, this dissertation demonstrates the effectiveness of eclectic approaches to elucidate complex ecological signals in Triassic temnospondyls. Additionally, the integrative framework applied in this dissertation accentuates and refines traditional views of temnospondyl palaeobiology and expands our perspective on the ecology, biogeography and plasticity of these taxa, underscoring their crucial role in Triassic ecosystems. The data presented in this thesis offers a multitude of future research endeavours. By combining the results of this dissertation with other comprehensive data sets the potential for continued advances in broader Triassic vertebrate palaeontology will be greatly enhanced, enabling significant insights into biodiversity patterns, evolutionary processes and ecological responses to environmental fluctuations.
The garden dormouse (Eliomys quercinus): ecology, habitat requirements and threats
(2025) Erhardt, Stefanie; Fietz, Joanna
Global biodiversity is declining rapidly, mainly as a result of anthropogenic pressures. Changes in land, such as deforestation and conversion to agriculture, are the main drivers of biodiversity loss, followed by direct exploitation such as hunting. Climate change and pollution are also contributing factors. The garden dormouse (Eliomys quercinus, Gliridae) is a small mammalian hibernator that has disappeared from more than 50% of its former range in recent decades, mainly in Eastern and Central Europe. The reasons for this decline are not yet fully understood. However, information on its biology, ecology, habitat requirements, and potential threats is needed to implement targeted conservation measures. To address this lack of knowledge, this study focuses on: 1. Filling knowledge gaps in the reproductive biology of the garden dormouse, including its genetic mating system and the timing of reproduction and hibernation (phenology), to better understand its life history strategies. 2. Identifying essential resources for the garden dormouse within the mountain forest, by investigating nesting behavior, home range use, and feeding ecology. 3. Characterizing potential threats for this species within the coniferous mountain forest by investigating the effects of climate change, the loss of essential resources, and habitat fragmentation. Therefore, a capture-mark-recapture study of the garden dormouse was conducted in the Northern Black Forest, one of its last natural distribution areas in Germany. To investigate the reproductive biology and the mating system of the garden dormouse, parentage analyses using five polymorphic microsatellite markers were combined with morphometric and behavioral data. Phenology was analyzed using capture-mark-recapture data in combination with morphometric measurements. To identify key resources during different life history stages, diet composition analysis in fecal samples and home range use and daytime resting sites were investigated by radio telemetry. Potential threats to the species were assessed by analyzing changes in body mass – used as a proxy for fitness – between two time periods (2003-2005 and 2018-2021), and by evaluating the effect of ambient winter temperatures on post-hibernation body mass. Based on the movement patterns of radio-tracked individuals, potential barrier effects of forest paths and trails were investigated. Genetic analyses and indirect indicators revealed that the garden dormouse is promiscuous. Typically for a promiscuous species garden dormice have relatively large testes and minimal sexual dimorphism. Males have extensive home ranges that overlap with those of several females, increasing the probability of mating encounters. This mating system maintains genetic variability, helping to avoid inbreeding and promotes offspring fitness. Garden dormice showed two birth peaks per year between 2003 and 2005, in contrast to only one birth peak in 2018-2021. Late-born juveniles grew faster to build sufficient fat reserves necessary for hibernation survival. The later onset of pre-hibernation fattening observed in adult females compared to adult males suggests that females must compensate for their higher energy demands during reproduction before hibernation starts. The home range provides essential resources for survival and reproduction, including food, resting sites, and mating partners. Garden dormice in the Black Forest showed a median home range size of 3.8 ha, with resting sites used in nest boxes and ground holes. However, ground holes were used more frequently during reproduction and low ambient temperatures, and are therefore an important resource especially during periods of high energy demand. The results of this study show that garden dormice are omnivorous with a preference for arthropods during the critical life history stages of juvenile growth and pre-hibernation fattening. Analyses of the crossing behavior showed that that adult garden dormice avoided crossing 4 m wide forest paths, which poses a significant threat to their survival by limiting their ability to colonize new areas, inhibiting gene flow and mate finding. In addition, this study also found that from 2018 to 2021, garden dormice had a reduced body mass during pre-hibernation fattening and growth compared to 2003 to 2005. As arthropods are the main food resource during this period, the ongoing insect decline may already be negatively affecting the availability of essential food resources, thereby reducing the survival probability of this population. This study found no effect of ambient temperature on post-hibernation body mass or phenology; however, the study sites were located at high altitudes where winters are still cold enough to ensure suitable hibernation conditions for garden dormice. Nonetheless, the ongoing climate change trends are predicted to further elevate winter temperatures even at higher altitudes, which could reduce the survival chances of this population in the future. To support the long-term survival of the garden dormouse, conservation measures should focus on the reduction of habitat fragmentation by rebuilding forest paths or, where this is not possible, creating underpasses with sufficient cover and connection to the surrounding habitat to facilitate dispersal and promiscuous mating. In addition, to support the garden dormouse during critical life history stages and to increase overall forest biodiversity and resilience, it is important to support food resources, especially arthropods, and resting sites by promoting forest structural diversity, increasing the amount of dead wood, and reducing pesticide use in the forest and the surrounding agricultural areas. In addition, natural resting sites such as ground holes should be supported by reducing the use of heavy timber machines and preserving structural habitat features such as rock crevices, underground burrows, tree holes, and cavities in dead wood. Implementing these conservation measures can mitigate the population decline of garden dormice. Reducing barrier effects, maintaining insect diversity and high structural diversity within forests can promote forest ecosystem resilience and support overall biodiversity.
Competitive hierarchies in bryozoan assemblages mitigate network instability by keeping short and long feedback loops weak
(2023) Koch, Franziska; Neutel, Anje-Margriet; Barnes, David K. A.; Tielbӧrger, Katja; Zarfl, Christiane; Allhoff, Korinna T.
Competitive hierarchies in diverse ecological communities have long been thought to lead to instability and prevent coexistence. However, system stability has never been tested, and the relation between hierarchy and instability has never been explained in complex competition networks parameterised with data from direct observation. Here we test model stability of 30 multispecies bryozoan assemblages, using estimates of energy loss from observed interference competition to parameterise both the inter- and intraspecific interactions in the competition networks. We find that all competition networks are unstable. However, instability is mitigated considerably by asymmetries in the energy loss rates brought about by hierarchies of strong and weak competitors. This asymmetric organisation results in asymmetries in the interaction strengths, which reduces instability by keeping the weight of short (positive) and longer (positive and negative) feedback loops low. Our results support the idea that interference competition leads to instability and exclusion but demonstrate that this is not because of, but despite, competitive hierarchy.
Unwanted souvenirs - import routes and pathogen detection of the non-endemic tick Rhipicephalus sanguineus s.l. in Germany
(2025) Fachet-Lehmann, Katrin; Lindau, Alexander; Mackenstedt, Ute
Ticks of the Genus Rhipicephalus occur worldwide. Especially members of Rh. sanguineus s.l. are primarily associated with dogs. As unwanted souvenirs, they are introduced by dogs into non-endemic areas such as Germany, where they can establish and reproduce indoors . A citizen-science study was conducted between 2019 and 2024, asking interested citizens to report tick infestations and send in travel related tick findings which were associated with dogs and were focused on Rhipicephalus species. Tick species were identified using the 16S rRNA gene and tested for pathogens associated with the genus Rhipicephalus . In addition, each tick introduction was considered as a case and categorized and analyzed individually. During the study period, 44 cases were reported. In 17 cases tick specimens were identified as Rh. sanguineus s.s., Rh. rutilus , Rh. linnaei, Rh. turanicus , and Rh. haemaphysaloides which were imported from other European countries and Sri Lanka. Neither Hepatozoon canis , Ehrlichia canis nor Babesia vogeli were detected in any of the 780 received specimens. In contrast, Rickettsia spp. was detected in 50 specimens from six independent cases, with Rickettsia massiliae being identified in 44 specimens. The import of dogs from abroad as well as travel with dogs lacking appropriate tick prophylaxis are responsible for more than 80% of cases. This Project highlights the risk of introductions of non-endemic tick species. Also, professionals such as veterinarians, animal welfare organizations and pest controllers need to be made aware of the possible introduction of Rhipicephalus spp. to ensure early recognition and rapid elimination of the ticks.
Societal changes in Ancient Greece impacted terrestrial and marine environments
(2025) Koutsodendris, Andreas; Maran, Joseph; Kotthoff, Ulrich; Lippold, Jörg; Knipping, Maria; Friedrich, Oliver; Gerdes, Axel; Kaboth-Bahr, Stefanie; Bahr, André; Schulz, Hartmut; Sakellariou, Dimitris; Pross, Jörg
The Aegean hosts some of the earliest cultural centers in European antiquity. To reconstruct the evolution of early anthropogenic impact in this region, we have examined lead (Pb) contents and vegetation dynamics on well-dated environmental archives extending to the early Holocene. We show that the impact of agropastoral societies on terrestrial ecosystems was locally confined during the Bronze and Iron Ages (5200–2750 years ago), although we record an onset of Pb pollution already at 5200 cal. years BP and thus about 1200 years earlier than previous archeological evidence. Our data demonstrate a marked increase in Pb pollution at 2150 cal. years BP that left an imprint across terrestrial and marine settings of the Aegean region. This first manifestation of marine pollution coincides with maximum deforestation and agricultural expansion, signaling pervasive human impact on ecosystems connected to the advanced monetized societies during the Hellenistic and Roman periods in Ancient Greece.
Habitat requirements and home range use of the threatened garden dormouse (Eliomys quercinus) in a coniferous forest
(2025) Erhardt, Stefanie; Pfister, Jan; Beier, Marieke; Vorderbrügge, Rieke; Förschler, Marc I.; Fietz, Joanna
Understanding habitat use and requirements is essential for the conservation of endangered species, such as the garden dormouse (Eliomys quercinus). Therefore, we radio-tracked garden dormice (n = 39) in the Black Forest National Park (Germany) between 2019 and 2021, determined home range size by calculating autocorrelated kernel density estimates, located resting sites during the day, and analyzed their resting behavior. Furthermore, we investigated their crossing behavior across paths varying in width, in the degree of canopy closure, and understory. Median home range size was 3.8 ha (Q25 = 2.3 ha, Q75 = 6.6 ha) in adults and 1.9 ha in juveniles. Adult males increased their home range sizes during reproduction. In September, shortly before hibernation, adults used smaller home ranges, likely to save energy. During the day, garden dormice used nest boxes and natural nests under the ground as resting sites. Ground holes were an important resource as they were most frequently used by reproductive individuals and also at low ambient temperatures (0.1–14.7 °C). In contrast, nest boxes were used only at higher ambient temperatures (> 5.9 °C). Forest trails with tree cover and/or undergrowth were frequently crossed by adults, while 4 m wide forest paths without tree cover or undergrowth were rarely crossed. The results of our study show that the preservation of natural resting sites, the restoration of forest trails, or the installation of crossing structures are important conservation measures for the garden dormouse, facilitating migration and colonization of new habitats and reducing the risk to lose genetic variability.
Phylogenomic approach to integrative taxonomy resolves a century‐old taxonomic puzzle and the evolutionary history of the Acromyrmex octospinosus species complex
(2024) Mera‐Rodríguez, Daniela; Fernández‐Marín, Hermógenes; Rabeling, Christian
Accurately delimiting species boundaries is essential for understanding biodiversity. Here, we assessed the taxonomy of the leaf‐cutting ants in the Acromyrmex octospinosus (Reich) species complex using an integrative approach incorporating morphological, population genetic, phylogenetic and biogeographical data. We sampled populations across the biogeographic distribution of the species complex and reconstructed their evolutionary relationships using ultraconserved elements (UCEs) as molecular markers. We evaluated traditional morphological characters used to distinguish putative taxa and performed species delimitation analyses to investigate divergence between evolutionary lineages. Our results support the hypothesis that the A. octospinosus species complex consists of two species: the widely distributed and polymorphic species A. octospinosus and its inquiline social parasite A. insinuator Schultz et al. We consider A. echinatior (Forel) syn. nov . and A. volcanus Wheeler syn. nov . as well as the subspecies A. octospinosus cubanus Wheeler syn. nov ., A. octospinosus ekchuah Wheeler syn. nov . and A. octospinosus inti Wheeler syn. nov . as junior synonyms of A. octospinosus . We also investigated the biogeographic history of the species complex and the evolutionary origin of the social parasite A. insinuator . We inferred that A. octospinosus originated during the late Miocene approximately 6.9 Ma ago in the Neotropical rainforest. Acromyrmex insinuator shared a common ancestor with A. octospinosus approximately 3.4 Ma ago, with a crown‐group age of approximately 0.9 Ma. Our phylogeny supports the hypothesis that the inquiline social parasite speciated via the intra‐specific route of social parasite evolution in direct sympatry from its host. Our findings reshape our understanding of the A. octospinosus species complex and provide a foundation for future studies of Acromyrmex leaf‐cutting ants.
Ontogenetic variation in the cranium of Mixosaurus cornalianus, with implications for the evolution of ichthyosaurian cranial development
(2023) Miedema, Feiko; Bindellini, Gabriele; Dal Sasso, Cristiano; Scheyer, Torsten M.; Maxwell, Erin E.
Relatively complete ontogenetic series are comparatively rare in the vertebrate fossil record. This can create biases in our understanding of morphology and evolution, since immaturity can represent a source of unrecognized intraspecific variation in both skeletal anatomy and ecology. In the extinct marine reptile clade Ichthyopterygia, ontogenetic series were widely studied only in some Jurassic genera, while the ontogeny of the oldest and most basal members of the clade is very poorly understood. Here, we investigate cranial ontogeny in Mixosaurus cornalianus , from the Middle Triassic Besano Formation of the Swiss and Italian Alps. This small-bodied taxon is represented by a wealth of material from multiple size classes, including fetal material. This allows us to assess ontogenetic changes in cranial morphology, and identify stages in the ontogenetic trajectory where divergence with more derived ichthyosaurs has occurred. Early ontogenetic stages of Mixosaurus show developmental patterns that are reminiscent of the presumed ancestral (early diverging sauropsid) condition. This is prominently visible in the late fetal stage in both the basioccipital, which shows morphology akin to basal tubera, and in the postorbital, which has a triradiate head. The ontogenetic trajectory of at least some of the cranial elements of Mixosaurus is therefore likely still very akin to the ancestral condition, even though the adult cranium diverges from the standard diapsid morphology.
Oncostatin M is a regulator of fibroblast growth factor 23 (FGF23) in UMR106 osteoblast-like cells
(2023) Münz, Sina; Feger, Martina; Föller, Michael
Renal phosphate and vitamin D metabolism is under the control of fibroblast growth factor 23 (FGF23), an endocrine and paracrine factor predominantly produced in bone. FGF23 formation is stimulated by active vitamin D, or parathyroid hormone (PTH), which are further regulators of phosphate homeostasis. In renal, inflammatory, and other diseases, plasma FGF23 reflects disease stage and correlates with outcome. Oncostatin M is part of the interleukin-6 (IL-6) family and regulates remodeling and PTH effects in bone as well as cardiac FGF23 production in heart failure via glycoprotein gp130. Here, we studied whether oncostatin M is a regulator of FGF23 in bone cells. Experiments were performed in UMR106 osteoblast-like cells, Fgf23 mRNA was determined by qRT-PCR, FGF23 protein by Western Blotting and ELISA, and oncostatin M receptor and leukemia inhibitory factor (LIF) receptor gene knockout accomplished by siRNA. As a result, oncostatin M dose-dependently up-regulated Fgf23 expression and protein secretion. The oncostatin M effect on FGF23 was mediated by oncostatin M receptor and gp130 and involved, at least in part, STAT3 and MEK1/2. Taken together, oncostatin M is a regulator of FGF23 through oncostatin M receptor, gp130, as well as STAT3 and MEK1/2 in UMR106 osteoblasts.
Tissue-level integration overrides gradations of differentiating cell identity in beetle extraembryonic tissue
(2024) Mann, Katie E.; Panfilio, Kristen A.; García-Sanz, José A.; Merino, Marisa M.; Chen, Lingyi
During animal embryogenesis, one of the earliest specification events distinguishes extraembryonic (EE) from embryonic tissue fates: the serosa in the case of the insects. While it is well established that the homeodomain transcription factor Zen1 is the critical determinant of the serosa, the subsequent realization of this tissue’s identity has not been investigated. Here, we examine serosal differentiation in the beetle Tribolium castaneum based on the quantification of morphological and morphogenetic features, comparing embryos from a Tc-zen1 RNAi dilution series, where complete knockdown results in amnion-only EE tissue identity. We assess features including cell density, tissue boundary morphology, and nuclear size as dynamic readouts for progressive tissue maturation. While some features exhibit an all-or-nothing outcome, other key features show dose-dependent phenotypic responses with trait-specific thresholds. Collectively, these findings provide nuance beyond the known status of Tc-Zen1 as a selector gene for serosal tissue patterning. Overall, our approach illustrates how the analysis of tissue maturation dynamics from live imaging extends but also challenges interpretations based on gene expression data, refining our understanding of tissue identity and when it is achieved.
Functionality of the Na+-translocating NADH:quinone oxidoreductase and quinol:fumarate reductase from Prevotella bryantii inferred from homology modeling
(2024) Hau, Jann-Louis; Schleicher, Lena; Herdan, Sebastian; Simon, Jörg; Seifert, Jana; Fritz, Günter; Steuber, Julia
Members of the family Prevotellaceae are Gram-negative, obligate anaerobic bacteria found in animal and human microbiota. In Prevotella bryantii , the Na + -translocating NADH:quinone oxidoreductase (NQR) and quinol:fumarate reductase (QFR) interact using menaquinone as electron carrier, catalyzing NADH:fumarate oxidoreduction. P. bryantii NQR establishes a sodium-motive force, whereas P. bryantii QFR does not contribute to membrane energization. To elucidate the possible mode of function, we present 3D structural models of NQR and QFR from P. bryantii to predict cofactor-binding sites, electron transfer routes and interaction with substrates. Molecular docking reveals the proposed mode of menaquinone binding to the quinone site of subunit NqrB of P. bryantii NQR. A comparison of the 3D model of P. bryantii QFR with experimentally determined structures suggests alternative pathways for transmembrane proton transport in this type of QFR . Our findings are relevant for NADH-dependent succinate formation in anaerobic bacteria which operate both NQR and QFR.
Crop cultivation in the Talayotic settlement of Son Fornés (Mallorca, Spain): agricultural practices on the western Mediterranean islands in the first millennium bce
(2024) Stika, Hans-Peter; Neugebauer, Aleta; Rihuete-Herrada, Cristina; Risch, Roberto; Micó, Rafael; Voltas, Jordi; Amengual, Paula; Gelabert, Lara; Lull, Vicente
The Balearic Islands were colonised around the transition from the Chalcolithic to the Bronze Age, not earlier than 2300 cal bce and certainly much later than any central or eastern Mediterranean islands. The number of archaeobotanical records is low and consists mainly of cereals and a few pulses. We present here new results of our long-term study of Son Fornés, an archaeological site on Mallorca which was occupied since the beginning of the Iron Age Talayotic period (~ 850 cal bce ) and until Roman times (123 bce onwards), in the Balearic Islands. In the Talayotic period of Son Fornés Hordeum vulgare var. vulgare (hulled barley) and Triticum aestivum/durum/turgidum (free-threshing wheat) were the main cereals grown and Vicia faba (broad bean) was the main pulse, while Avena sp. (oats) is considered to have been a weed but was nonetheless consumed and was probably in an early phase of being domesticated. For the subsequent post-Talayotic (ca. 550 − 250 bce ), Classic I and Classic II, the Republican Roman occupation period (from 123 bce onwards) the databases are weak, displaying hulled barley as the main crop and broad bean as the main pulse. The archaeobotanical records of Ficus carica (fig), Olea europaea (olive) and Vitis vinifera (grapevine) represent wild or cultivated and domesticated forms. Prunus dulcis (almond) and Pinus pinea (stone pine) were found on Eivissa (Ibiza), pointing to a Phoenician introduction to the islands, while Phoenix dactylifera (date palm) and Castanea sativa (chestnut), found on Menorca, might have been brought in by the Romans. The number of crops being used on the Balearic Islands was limited when compared to sites of similar periods on the European mainland or the central and eastern Mediterranean islands. According to carbon isotope results of Δ 13 C, hulled barley grew under damper conditions than free-threshing wheat. The high δ 15 N values indicated that both crops were well-manured with animal dung during the entire occupation period.
Influence of rhizospheric symbiotic microorganisms on the behavioural effects of antimony in soil-plant system: insights from a proteomic perspective
(2024) Zhou, Min; Li, Hui; Xi, Lin; Shi, Feng; Li, Xinru; Wang, Fanfan; Liu, Xuesong; Su, Hailei; Wei, Yuan
Antimony (Sb) pollution in soil-rice systems can affect human health by enriching of food chains. Currently, the mechanism of the negative role underlying microorganisms in plant responses to Sb stress remains clear. The results of this study showed that the presence of arbuscular mycorrhizal (AM) fungi, a common symbiotic microorganism in rhizosphere soil, significantly enhanced Sb uptake by upland rice and inhibited its growth. Furthermore, we explained the reasons for the adverse effects of AM fungi mediation on upland rice growth under Sb stress from a molecular perspective. The results also showed that AM fungi affect the biological processes of the response of upland rice to oxidative stress and the functions of its antioxidant active molecules throughout the vegetative growth phase of upland rice, and that the phenylpropanoid biosynthesis pathway is significantly downregulated. At the same time, phenylalanine/tyrosine ammonia-lyase (PTAL) in the pathway was significantly expressed in the middle and late stages of vegetative growth of upland rice. Therefore, PTAL can act as a potential reference protein to investigate the response of upland rice to Sb stress mediated by AM fungi. These findings enrich our understanding of the impact of Sb pollution on soil-plant systems in real soil environments.
Ontogenetic variation in the skull of Stenopterygius quadriscissus with an emphasis on prenatal development
(2022) Miedema, Feiko; Maxwell, Erin E.
The availability of a large sample size from a range of ontogenetic stages makes Stenopterygius quadriscissus a good model to study ontogenetic variation in a fossil sauropsid. We qualitatively examined pre- and postnatal ontogenetic changes in the cranium of S. quadriscissus . The prenatal ossification sequence is similar to other diapsids, exhibiting delayed chondrocranial ossification compared to the dermatocranium. In the dermatocranium, the circumorbital area is more ossified earlier in development relative to other elements, especially those of the skull roof where ossification is comparatively weaker across prenatal stages. Perinatally all cranial elements are ossified, and many scarf and step joints are already closed. We propose four prenatal and three postnatal stages in S. quadriscissus on the basis of relative ossification, size and qualitative cranial characters pertaining to the jugal, parietal, frontal, pterygoid and surangular. These will provide a basis for determining ontogenetic stages in other ichthyosaurs. Moreover, our postnatal observations aid in refining ontogenetic characters for phylogenetic studies. Lastly, we observed that the antimeric sutures of the midline of the skull roof are open perinatally and that fusion of the midline only appears in the adult stage. We hypothesize that the loose connection of the midline functions as a fontanelle, limiting potential damage during birth.
Modelling net CO₂ assimilation of two Sphagnum species from temperature and water content response
(2025) Perera‐Castro, Alicia V.; Nadal, Miquel
Photosynthesis and respiration respond differently to the combined effects of temperature and water status. Quantifying their responses is crucial to predict the carbon balance of Sphagnum peatlands in different scenarios of climate change. A first approach was done for two Sphagnum species inhabiting a boreal peatland in Finland. Gas exchange at different temperatures and moss hydration were measured to model net assimilation using simultaneous measurements of photosynthesis and dark respiration. In addition, measurements of moss surface temperature at different water content were performed in the field, covering natural conditions of sun exposure and air temperature. We also accounted for the interaction effect between moss canopy temperature and air temperature, radiation, and water content. Our model accurately predicted net assimilation and was used to estimate net primary productivity based on meteorological inputs and moss water content. The two Sphagnum species presented optimum temperatures for net CO2 assimilation around 25°C, with minimum changes at other temperatures. In contrast, dark respiration increased exponentially with temperature, which makes losses of carbon during the night and the duration of dark conditions key determinants in the carbon balance of Sphagnum. The modeled net primary productivity revealed an enhancement of CO2 fixation under warming conditions (averaged +10°C), concomitant to the expected transformation of peatlands from sink to source of CO2. Our model highlighted the importance of respiration restriction in ensuring positive assimilation in Sphagnum. Therefore, day and night temperature oscillation and short night photoperiods are more important than the optimum temperature of photosynthesis for carbon balance.
Metabolic rewiring compensates for the loss of amino acid biosynthesis in Bacillus subtilis
(2024) Yousef Mardoukhi, Mohammad Saba; Commichau, Fabian M.
Amino acids are considered as some of the earliest organic molecules to form on Earth. Serving as the building blocks of proteins, they are intricately connected to nearly every life process. Therefore, amino acid metabolism needs to be precisely regulated in any living organism. Amino acid metabolism includes the biochemical pathways responsible for the synthesis, degradation, and utilization of amino acids. Most of the bacteria, particularly the Gram-positive model bacterium Bacillus subtilis, have the capability to synthesize all proteinogenic amino acids or, if available, import them from the environment. Throughout evolution, different metabolic pathways have emerged to maintain metabolites level inside the cells. Some biosynthetic pathways are unknown as they are not primary routes or are typically inactive under normal conditions. However, they may become active under specific circumstances. Two very important pathways, previously not known to be substituted by alternative routes, involve de novo biosynthesis of glutamate, which is an essential amino group donor in every cell. Many bacteria can synthesize glutamate using a NADPH + H+-dependent glutamate dehydrogenase (GDH). Alternatively, glutamate can be produced by the combined action of the ATP-dependent glutamine synthetase (GS) and the NADPH + H+-dependent glutamate synthase (GOGAT). B. subtilis only employs the GS-GOGAT pathway for de novo synthesis of glutamate. In the context of this work, it was shown that a B. subtilis deficient for the GS-GOGAT pathway may employ the aspartase AnsB and aspartate transaminase AspB for the synthesis of glutamate in biologically significant amounts. Genetic analyses revealed that the aspartase AnsB converts ammonium and the tricarboxylic acid cycle intermediate fumarate to aspartate. Subsequently, the aspartate transaminase AspB transfers the amino group from aspartate to α-ketoglutarate, resulting in the production of L-glutamate and oxaloacetate. This observation challenges the well-established point of view of whether the GS-GOGAT-dependent pathway is indeed the only route for de novo synthesis of glutamate in nature. It was also set out to explore which amino acids could serve as the sole sources of carbon and nitrogen in the background of a B. subtilis strain that is a genetically stable glutamate auxotroph. The aim was to understand the conversion of the amino acids into glutamate and further to α-ketoglutarate, a reaction that is facilitated by the enzymatic activity of the GDHs RocG/GudB. It turned out that some of the amino acids are toxic for B. subtilis. However, B. subtilis can quickly develop resistance by the acquisition of mutations that result in reduced and enhanced amino acid uptake and export, respectively. Moreover, the toxicity of some amino acids may be reduced by increased degradation of glutamate. Furthermore, with focus on the toxicity of asparagine, it could be demonstrated that AimA, which has been characterized as a general amino acid importer, serves as a low affinity asparagine transporter in B. subtilis. Finally, AzlCD, which was previously described as an exporter for histidine and branched-chain amino acids, also exports asparagine. Thus, B. subtilis can adapt to amino acid toxicity in various ways.

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