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Virtual currencies have gained popularity as part of the digital transformation of the financial system. In particular stablecoins are becoming increasingly popular with consumers. The tokens, which are pegged to a value and - according to their name - promise price stability, pose significant risks from which consumers need to be protected. This article focuses first on consumerspecific risks (B.) and German consumer protection law and in particular on the applicability of a right of withdrawal from the acquisition of stablecoins (C.). Subsequently, the EU legislator’s effort to minimize price stability as well as transparency and exchangeability risks, the Markets in Crypto-assets Regulation (2023/1114), is examined in terms of its consumer protection instruments (D.).
Mitochondria and chloroplasts are of endosymbiotic origin. Their integration into cells entailed the development of protein translocons, partially by recycling bacterial proteins. We demonstrate the evolutionary conservation of the translocon component Tic22 between cyanobacteria and chloroplasts. Tic22 in Anabaena sp. PCC 7120 is essential. The protein is localized in the thylakoids and in the periplasm and can be functionally replaced by a plant orthologue. Tic22 physically interacts with the outer envelope biogenesis factor Omp85 in vitro and in vivo, the latter exemplified by immunoprecipitation after chemical cross-linking. The physical interaction together with the phenotype of a tic22 mutant comparable with the one of the omp85 mutant indicates a concerted function of both proteins. The three-dimensional structure allows the definition of conserved hydrophobic pockets comparable with those of ClpS or BamB. The results presented suggest a function of Tic22 in outer membrane biogenesis.
Background: Although Tic22 is involved in protein import into chloroplasts, the function in cyanobacteria is unknown.
Results: Cyanobacterial Tic22 is required for OM biogenesis, shares structural features with chaperones, and can be substituted by plant Tic22.
Conclusion: Tic22, involved in outer membrane biogenesis, is functionally conserved in cyanobacteria and plants.
Significance: The findings are important for the understanding of periplasmic protein transport.
Proteins of the Omp85 family are conserved in all kingdoms of life. They mediate protein transport across or protein insertion into membranes and reside in the outer membranes of Gram-negative bacteria, mitochondria, and chloroplasts. Omp85 proteins contain a C-terminal transmembrane β-barrel and a soluble N terminus with a varying number of polypeptide-transport-associated or POTRA domains. Here we investigate Omp85 from the cyanobacterium Anabaena sp. PCC 7120. The crystallographic three-dimensional structure of the N-terminal region shows three POTRA domains, here named P1 to P3 from the N terminus. Molecular dynamics simulations revealed a hinge between P1 and P2 but in contrast show that P2 and P3 are fixed in orientation. The P2-P3 arrangement is identical as seen for the POTRA domains from proteobacterial FhaC, suggesting this orientation is a conserved feature. Furthermore, we define interfaces for protein-protein interaction in P1 and P2. P3 possesses an extended loop unique to cyanobacteria and plantae, which influences pore properties as shown by deletion. It now becomes clear how variations in structure of individual POTRA domains, as well as the different number of POTRA domains with both rigid and flexible connections make the N termini of Omp85 proteins versatile adaptors for a plentitude of functions.
In high light, the antenna system in oxygenic photosynthetic organisms switches to a photoprotective mode, dissipating excess energy in a process called non-photochemical quenching (NPQ). Diatoms exhibit very efficient NPQ, accompanied by a xanthophyll cycle in which diadinoxanthin is de-epoxidized into diatoxanthin. Diatoms accumulate pigments from this cycle in high light, and exhibit faster and more pronounced NPQ. The mechanisms underlying NPQ in diatoms remain unclear, but it can be mimicked by aggregation of their isolated light-harvesting complexes, FCP (fucoxanthin chlorophyll-a/c protein). We assess this model system by resonance Raman measurements of two peripheral FCPs, trimeric FCPa and nonameric FCPb, isolated from high- and low-light-adapted cells (LL, HL). Quenching is associated with a reorganisation of these proteins, affecting the conformation of their bound carotenoids, and in a manner which is highly dependent on the protein considered. FCPa from LL diatoms exhibits significant changes in diadinoxanthin structure, together with a smaller conformational change of at least one fucoxanthin. For these LL-FCPa, quenching is associated with consecutive events, displaying distinct spectral signatures, and its amplitude correlates with the planarity of the diadinoxanthin structure. HL-FCPa aggregation is associated with a change in planarity of a 515-nm-absorbing fucoxanthin, and, to a lesser extent, of diadinoxanthin. Finally, in FCPb, a blue-absorbing fucoxanthin is primarily affected. FCPs thus possess a plastic structure, undergoing several conformational changes upon aggregation, dependent upon their precise composition and structure. NPQ in diatoms may therefore arise from a combination of structural changes, dependent on the environment the cells are adapted to.
Microbial rhodopsins are omnipresent on Earth, however the vast majority of them remain uncharacterized. Here we describe a new rhodopsin clade from cold-adapted organisms and cold environments, such as glaciers, denoted as CryoRhodopsins (CryoRs). Our data suggest that CryoRs have photosensory activity. A distinguishing feature of the clade is the presence of a buried arginine residue close to the cytoplasmic face of its members. Combining single-particle cryo-electron microscopy and X-ray crystallography with the rhodopsin activation by light, we demonstrate that the arginine stabilizes a strongly blue-shifted intermediate of an extremely slow CryoRhodopsin photocycle. Together with extensive spectroscopic characterization, our investigations on CryoR1 and CryoR2 proteins reveal mechanisms of photoswitching in the newly identified clade and demonstrate principles of the adaptation of these rhodopsins to low temperatures.
Microbial rhodopsins are omnipresent on Earth, however the vast majority of them remain uncharacterized. Here we describe a new rhodopsin group from cold-adapted organisms and cold environments, such as glaciers, denoted as CryoRhodopsins (CryoRs). Our data suggest that CryoRs have dual functionality switching between inward transmembrane proton translocation and photosensory activity, both of which can be modulated with UV light. CryoR1 exhibits two subpopulations in the ground state, which upon light activation lead to transient photocurrents of opposing polarities. A distinguishing feature of the group is the presence of a buried arginine residue close to the cytoplasmic face of its members. Combining single-particle cryo-electron microscopy and X-ray crystallography with the rhodopsin activation by lit, we demonstrate that the arginine stabilizes a UV-absorbing intermediate of an extremely slow CryoRhodopsin photocycle. Together with extensive spectroscopic characterization, our investigations on CryoR1 and CryoR2 proteins reveal mechanisms of photoswitching in the newly identified group and demonstrate principles of the adaptation of these rhodopsins to low temperatures.Microbial rhodopsins are omnipresent on Earth, however the vast majority of them remain uncharacterized. Here we describe a new rhodopsin group from cold-adapted organisms and cold environments, such as glaciers, denoted as CryoRhodopsins (CryoRs). Our data suggest that CryoRs have dual functionality switching between inward transmembrane proton translocation and photosensory activity, both of which can be modulated with UV light. CryoR1 exhibits two subpopulations in the ground state, which upon light activation lead to transient photocurrents of opposing polarities. A distinguishing feature of the group is the presence of a buried arginine residue close to the cytoplasmic face of its members. Combining single-particle cryo-electron microscopy and X-ray crystallography with the rhodopsin activation by light, we demonstrate that the arginine stabilizes a UV-absorbing intermediate of an extremely slow CryoRhodopsin photocycle. Together with extensive spectroscopic characterization, our investigations on CryoR1 and CryoR2 proteins reveal mechanisms of photoswitching in the newly identified group and demonstrate principles of the adaptation of these rhodopsins to low temperatures.
Methods using environmental DNA to explore and analyze biodiversity from previously unexplored habitats and ecosystems have become increasingly popular in recent years. This is particularly due to the potential reduction in necessary taxonomic expertise, the opportunity to assess microorganismal communities, and decreased time investments required to cover large spatial extents. In forests, the surface of tree bark is an important habitat for epiphytic diversity. Because of the large surface area rich in micro-niches, the seasonal stability of the substrate, and the longevity of trees, tree bark surfaces provide an ideal habitat for many species. Yet, we lack a comprehensive understanding of their communities and the environmental drivers behind the community assembly. These missing links hinder the exploration of the forest microbiome as a whole and limits our understanding of functions of a large forest habitat and its connections to other forest microbiomes. With a holistic eDNA metabarcoding approach, encompassing samples of three major taxonomic groups (e.g. bacteria, fungi, and green algae), as well as simultaneous collections from multiple forest habitats we can contribute to closing these gaps and increase our knowledge of the forest microbiome.
My dissertation is set within the framework of the Biodiversity Exploratories and was conducted in four parts: I. the establishment of an eDNA metabarcoding workflow to reveal the local diversity of the bark surface microbiome; II. the upscaling of the method to large geographic and environmental gradients to uncover the drivers of the microbiome; III. the integration of soil and bark samples to investigate compositional differences in two important forest habitats; IV. the evaluation of eDNA metabarcoding as a tool for biodiversity assessments of lichen diversity in forests.
In the first part, I developed a simple, cost-effective and fast sampling strategy to acquire eDNA samples from the bark of trees in forest ecosystems. Using readily available medical-specimen-collection swabs I sampled bark surfaces of individual trees in Central German forests and used metabarcoding to amplify marker genes of green algae, fungi and bacteria. From the sequencing reads I calculated the first diversity estimates of the major organismal groups of bark surface microbiomes from Central European forests. Overall the methodology produced reliable results, allowing for an expanded sampling in the second part.
In the second part of the dissertation, I expanded the sampling based on the results of part one. I collected bark surface samples from the three regions of the Biodiversity Exploratories covering large spatial and environmental gradients representative for Central European forests. The collection included composite samples from 150 plots and over 750 trees. Utilizing measurements of climatic and forest structure variables provided by the Biodiversity Exploratories, as well as my own community data, I identified the biotic and abiotic drivers behind alpha and beta diversity of the bark surface microbiome.
In the third part, I studied the differences between the bark surface as an unexplored and the soil as an example of a well characterized forest microbiome. Using only the fungal part of the large sampling campaign and soil samples obtained from the same plots at the same time, I assessed the commonalities and differences of the micro-communities of these distinct forest niches. Furthermore, I included two coniferous and one deciduous tree species to examine, if the effect of tree species, previously shown for soil microbiomes, also holds true for the bark surface.
In the last part of my dissertation, I used eDNA in a more applied way as a tool in biodiversity assessments of lichenized fungi. I compared the results from eDNA metabarcoding to an expert floristic mapping conducted in the same plots in 2007/2008. I assigned functional guilds to the fungal taxa obtained in the large sampling campaign and used a subset that was assigned as lichenized fungi.
In conclusion, I showed that eDNA metabarcoding is a valuable tool to reveal the unknown diversity of microorganisms in forest ecosystems. In particular, my results advance our understanding of the bark surface microbiome, an underexplored habitat within forests. The tightly linked interactions of the three major microbial groups underline that studies need to take holistic approaches across multiple taxonomic groups to deepen our understanding of processes governing the assembly of microbiomes. Results from my dissertation may serve as a foundation to inform hypotheses addressing the functions of forest microbiomes. The massive diversity data collected may also contribute to closing the gap in our understanding of macro-organisms and micro-organisms with respect to diversity distributions and patterns of richness, and serve as a baseline for predictions of biodiversity responses under future anthropogenic change.
Abstract
Natural plant populations often harbour substantial heritable variation in DNA methylation. However, a thorough understanding of the genetic and environmental drivers of this epigenetic variation requires large-scale and high-resolution data, which currently exist only for a few model species. Here, we studied 207 lines of the annual weed Thlaspi arvense (field pennycress), collected across a large latitudinal gradient in Europe and propagated in a common environment. By screening for variation in DNA sequence and DNA methylation using whole-genome (bisulfite) sequencing, we found significant epigenetic population structure across Europe. Average levels of DNA methylation were strongly context-dependent, with highest DNA methylation in CG context, particularly in transposable elements and in intergenic regions. Residual DNA methylation variation within all contexts was associated with genetic variants, which often co-localized with annotated methylation machinery genes but also with new candidates. Variation in DNA methylation was also significantly associated with climate of origin, with methylation levels being lower in colder regions and in more variable climates. Finally, we used variance decomposition to assess genetic versus environmental associations with differentially methylated regions (DMRs). We found that while genetic variation was generally the strongest predictor of DMRs, the strength of environmental associations increased from CG to CHG and CHH, with climate-of-origin as the strongest predictor in about one third of the CHH DMRs. In summary, our data show that natural epigenetic variation in Thlaspi arvense is significantly associated with both DNA sequence and environment of origin, and that the relative importance of the two factors strongly depends on the sequence context of DNA methylation. T. arvense is an emerging biofuel and winter cover crop; our results may hence be relevant for breeding efforts and agricultural practices in the context of rapidly changing environmental conditions.
Author summary
Variation within species is an important level of biodiversity, and it is key for future adaptation. Besides variation in DNA sequence, plants also harbour heritable variation in DNA methylation, and we want to understand the evolutionary significance of this epigenetic variation, in particular how much of it is under genetic control, and how much is associated with the environment. We addressed these questions in a high-resolution molecular analysis of 207 lines of the common plant field pennycress (Thlaspi arvense), which we collected across Europe, propagated under standardized conditions, and sequenced for their genetic and epigenetic variation. We found large geographic variation in DNA methylation, associated with both DNA sequence and climate of origin. Genetic variation was generally the stronger predictor of DNA methylation variation, but the strength of environmental association varied between different sequence contexts. Climate-of-origin was the strongest predictor in about one third of the differentially methylated regions in the CHH context, which suggests that epigenetic variation may play a role in the short-term climate adaptation of pennycress. As pennycress is currently being domesticated as a new biofuel and winter cover crop, our results may be relevant also for agriculture, particularly in changing environments.
The cleptoparasitic bee genus Triepeolus Robertson, 1901 (Hymenoptera: Apidae) is revised for species occurring in South America. A total of nine species are confirmed from the continent, of which T. tuberculifer Onuferko, Rightmyer & Roig-Alsina sp. nov. is newly described. Four new synonymies are proposed: T. aguilari Moure, 1955 syn. nov. and T. megadelphus Cockerell, 1914 syn. nov. under T. buchwaldi (Friese, 1908); T. bilineatus Cockerell, 1949 syn. nov. under T. flavipennis (Friese, 1916); and Epeolus merus Brèthes, 1909 syn. nov. under T. nemoralis (Holmberg, 1886). Males of T. alvarengai Moure, 1955 and T. rufotegularis (Ashmead, 1900) and females of T. atoconganus Moure, 1955 and T. cecilyae Packer, 2016 are described for the first time. Lectotypes are designated for the following (all originally described under Epeolus Latreille, 1802 but now recognized as Triepeolus): E. buchwaldi, E. flavipennis, E. osiriformis Schrottky, 1910 and its junior synonym E. luteipes Friese, 1916, and E. rufotegularis. Diagnoses and complete descriptions/redescriptions are provided for all species, along with a fully illustrated dichotomous identification key (with Portuguese and Spanish versions available as supplementary material) to distinguish them based on external morphological features. Additionally, known collection records and information about the ecology of the treated species are presented.
Biotechnological processes offer better production conditions for a wide variety of goods of industrial interest. The production of aromatic compounds, for example, involves molecules of great value for cosmetic, plastic, agrochemical and pharmaceutic industries. However, the yield of such processes frequently prevents a proper implementtation that would allow the replacement of traditional production processes.
Numerous rational engineering approaches have been attempted to enhance metabolic pathways associated with desired products. Unfortunately, genetic modifications and heterologous pathway expression often lead to a higher metabolic burden on the producing organisms, ultimately leading to reduced production levels and fitness.
This project utilised adaptive laboratory evolution to better understand the development of synthetic cooperative consortia, using S. cerevisiae as a model organism. Specifically, a synthetic cooperative consortium was developed around the exchange of lysine and tyrosine, which was subjected to adaptive laboratory evolution aiming to induce mutations that would improve the system’s fitness either by enhanced production or upgraded stress resistance. Consequently, the mutant strains isolated after the evolution rounds were sequenced to identify relevant variations that could be related to the growth and production phenotypes observed.
The insights derived from this project are expected to contribute to further developing synthetic cooperative consortia with utilitarian purposes.