Effects of mining activities on fish communities and food web dynamics in a lowland river

Fish communities of streams and rivers might be substantially subsidized by terrestrial insects that fall into the water. Although such animal‐mediated fluxes are increasingly recognized, little is known about how anthropogenic perturbations may influence the strength of such exchanges. Intense land use, such as lignite mining, may impact a river ecosystem due to the flocculation of iron (III) oxides, thus altering food web dynamics. We compared sections of the Spree River in North‐East Germany that were greatly influenced by iron oxides with sections located downstream of a dam where passive remediation technologies are applied. Compared to locations downstream of the dam, the abundance of benthic macroinvertebrates at locations of high iron concentrations upstream of the dam was significantly reduced. Similarly, catch per unit effort of all fish was significantly higher in locations downstream of the dam compared to locations upstream of the dam, and the condition of juvenile and adult piscivorous pike Esox lucius was significantly lower in sections of high iron concentrations. Using an estimate of short‐term (i.e., metabarcoding of the gut content) as well as longer‐term (i.e., hydrogen stable isotopes) resource use, we could demonstrate that the three most abundant fish species, perch Perca fluviatilis, roach Rutilus rutilus, and bleak Alburnus alburnus, received higher contributions of terrestrial insects to their diet at locations of high iron concentration. In summary, lotic food webs upstream and downstream of the dam greatly differed in the overall structure with respect to the energy available for the highest tropic levels and the contribution of terrestrial insects to the diet of omnivorous fish. Therefore, human‐induced environmental perturbations, such as river damming and mining activities, represent strong pressures that can alter the flow of energy between aquatic and terrestrial systems, indicating a broad impact on the landscape level.Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659Fischereiabgabe Brandenburg, Ministerium für Landwirtschaft, Umwelt und Klimaschutz des Landes BrandenburgPeer Reviewe

One-dimensional array of ion chains coupled to an optical cavity

We present a novel hybrid system where an optical cavity is integrated with a microfabricated planar-electrode ion trap. The trap electrodes produce a tunable periodic potential allowing the trapping of up to 50 separate ion chains spaced by 160 $\mu$m along the cavity axis. Each chain can contain up to 20 individually addressable Yb\textsuperscript{+} ions coupled to the cavity mode. We demonstrate deterministic distribution of ions between the sites of the electrostatic periodic potential and control of the ion-cavity coupling. The measured strength of this coupling should allow access to the strong collective coupling regime with $\lesssim$10 ions. The optical cavity could serve as a quantum information bus between ions or be used to generate a strong wavelength-scale periodic optical potential.Comment: 15 pages, 6 figures, submitted to New Journal of Physic

A Decision Support System to Predict Acute Fish Toxicity

We present a decision support system using a Bayesian network to predict acute fish toxicity from multiple lines of evidence. Fish embryo toxicity testing has been proposed as an alternative to using juvenile or adult fish in acute toxicity testing for hazard assessments of chemicals. The European Chemicals Agency has recommended the development of a so-called weight-of-evidence approach for strengthening the evidence from fish embryo toxicity testing. While weight-of-evidence approaches in the ecotoxicology and ecological risk assessment community in the past have been largely qualitative, we have developed a Bayesian network for using fish embryo toxicity data in a quantitative approach. The system enables users to efficiently predict the potential toxicity of a chemical substance based on multiple types of evidence including physical and chemical properties, quantitative structure-activity relationships, toxicity to algae and daphnids, and fish gill cytotoxicity. The system is demonstrated on three chemical substances of different levels of toxicity. It is considered as a promising step towards a probabilistic weight-of-evidence approach to predict acute fish toxicity from fish embryo toxicity.publishedVersio

Adverse Outcome Pathways during Early Fish Development: A Conceptual Framework for Identification of Chemical Screening and Prioritization Strategies

The fish early life-stage (FELS) test guideline (OECD 210 or OCSPP 850.1400) is the most frequently used bioassay for predicting chronic fish toxicity and supporting aquatic ecological risk assessments around the world. For each chemical, the FELS test requires a minimum of 360 fish and 1 to 3 months from test initiation to termination. Although valuable for predicting fish full life-cycle toxicity, FELS tests are labor and resource intensive and, due to an emphasis on apical endpoints, provide little to no information about chemical mode of action. Therefore, the development and implementation of alternative testing strategies for screening and prioritizing chemicals has the potential to reduce the cost and number of animals required for estimating FELS toxicity and, at the same time, provides insights into mechanisms of toxicity. Using three reference chemicals with well-established yet distinct adverse outcome pathways (AOPs) in early life stages of fish, we proposed FELS-specific AOPs as conceptual frameworks for identifying useful chemical screening and prioritization strategies. The reference chemicals selected as case studies were a cardiotoxic aryl hydrocarbon receptor agonist (2,3,7,8-tetrachlorodibenzo-p-dioxin), neurotoxic acetylcholinesterase inhibitor (chlorpyrifos), and narcotic surfactant (linear alkylbenzene sulfonate). Using qualitative descriptions for each chemical during early fish development, we developed generalized AOPs and, based on these examples, proposed a three-tiered testing strategy for screening and prioritizing chemicals for FELS testing. Linked with biologically based concentration-response models, a tiered testing strategy may help reduce the reliance on long-term and costly FELS tests required for assessing the hazard of thousands of chemicals currently in commerc

Design and biofabrication of a leaf-inspired vascularized cell-delivery device

We designed and biofabricated a channeled construct as a possible cell-delivery device that can be endothelialized to overcome size limitations due to oxygen diffusion. The channeled device mimicking a leaf was designed using computer-aided design software, with fluid flow through the channels visualized using simulation studies. The device was fabricated either by form casting using a custom 3D-printed plastic mold or by 3D-bioprinting using Pluronic F-127 as sacrificial ink to print the channels. The actual leaf was cast or bioprinted using hydrogel made from a mixture of tunicate cellulose nanofibers and alginate that was cross-linked in calcium chloride solution to allow a stable device. The resulting device was a 20 7 8 7 3 mm or 35 7 18 7 3 mm (length 7 width 7 height) leaf with one main channel connected to several side channels. Surface modification using periodate oxidation, followed by laminin bioconjugation, was performed to enhance endothelial cell adhesion in the channels. We subsequently used human umbilical vein endothelial cells to demonstrate the efficacy of the device for promoting endothelialization. These results indicated that the biofabricated device has great potential for use in tissue-engineering for various applications associated with the need of perfusable vasculature

Impact of ambient conditions on the Si isotope fractionation in marine pore fluids during early diagenesis

Benthic fluxes of dissolved silica (Si) from sediments into the water column are driven by the dissolution of biogenic silica (bSiO2) and terrigenous Si minerals and modulated by the precipitation of authigenic Si phases. Each of these processes has a specific effect on the isotopic composition of silica dissolved in sediment pore waters such that the determination of pore water δ30Si values can help to decipher the complex Si cycle in surface sediments. In this study, the δ30Si signatures of pore fluids and bSiO2 in the Guaymas Basin (Gulf of California) were analyzed, which is characterized by high bSiO2 accumulation and hydrothermal activity. The δ30Si signatures were investigated in the deep basin, in the vicinity of a hydrothermal vent field, and at an anoxic site located within the pronounced oxygen minimum zone (OMZ). The pore fluid δ30Sipf signatures differ significantly depending on the ambient conditions. Within the basin, δ30Sipf is essentially uniform averaging +1.2 ± 0.1 ‰ (1SD). Pore fluid δ30Sipf values from within the OMZ are significantly lower (0.0 ± 0.5 ‰, 1SD), while pore fluids close to the hydrothermal vent field are higher (+2.0 ± 0.2 ‰, 1SD). Reactive transport modelling results show that the δ30Sipf is mainly controlled by silica dissolution (bSiO2 and terrigenous phases) and Si precipitation (authigenic aluminosilicates). Precipitation processes cause a shift to high pore fluid δ30Sipf signatures, most pronounced at the hydrothermal site. Within the OMZ however, additional dissolution of isotopically depleted Si minerals (e.g. clays) facilitated by high mass accumulation rates of terrigenous material (MARterr) is required to promote the low δ30Sipf signatures while precipitation of authigenic aluminosilicates seems to be hampered by high water / rock ratios. Guaymas OMZ δ30Sipf values are markedly different from those of the Peruvian OMZ, the only other marine setting where Si isotopes have been investigated to constrain early diagenetic processes. These differences highlight the fact that δ30Sipf signals in OMZs worldwide are not alike and each setting can result in a range of δ30Sipf values as a function of the environmental conditions. We conclude that the benthic silica cycle is more complex than previously thought and that additional Si isotope studies are needed to decipher the controls on Si turnover in marine sediment and the role of sediments in the marine silica cycle

Molekulare Charakterisierung einer Wildgerstenintrogression mit dem Gelbverzwergungsresistenzgen Ryd4Hb im Genom der Kulturgerste

Zusammenfassung Aus einer interspezifischen Kreuzung der Wintergerste Hordeum vulgare cv. 'Igri' mit der virusresistenten Wildgerste H. bulbosum wurden spaltende Kartierungspopulationen entwickelt, die eine 3HL-Introgression tragen, welche Resistenz gegenüber BYDV vermittelt. Die genetische Analyse einer BC2F4-Familie zeigte eine monohybride Aufspaltung der Resistenz mit dominanter Merkmalsausprägung. Es konnten bisher vier Gersten- Ankermarker und vier TC-Marker um das Resistenzgen Ryd4Hb kartiert werden. Zwei der aus den orthologen Bereichen des Reisgenoms abgeleiteten TC-Marker kosegregieren mit dem Resistenzgen Ryd4Hb. Stichwörter: Hordeum vulgare, Hordeum bulbosum, BYDV, Resistenz, Selektionsmarker   Abstract Interspecific crosses between winter barley H. vulgare cv. 'Igri' and a virus-resistant accession of the wild species H. bulbosum yielded mapping populations segregating with individuals resistant towards barley yellow dwarf virus. Genetic analysis of a BC2F4 family revealed a dominant inheritance of the resistance. GISH analysis indicated an Hb introgression on chromosome 3HL. Four 3HL barley anchor markers and four TC markers of the orthologous rice genome region, respectively, were mapped on either side of the resistance locus Ryd4Hb. Two of the TC markers cosegregated with the BYDV resistance. Keywords: Hordeum vulgare, Hordeum bulbosum, BYDV, resistance, selection marker

High-resolution analysis of individual Drosophila melanogaster larvae uncovers individual variability in locomotion and its neurogenetic modulation

Neuronally orchestrated muscular movement and locomotion are defining faculties of multicellular animals. Due to its simple brain and genetic accessibility, the larva of the fruit fly Drosophila melanogaster allows one to study these processes at tractable levels of complexity. However, although the faculty of locomotion clearly pertains to the individual, most studies of locomotion in larvae use measurements aggregated across animals, or animals tested one by one, an extravagance for larger-scale analyses. This prevents grasping the inter- and intra-individual variability in locomotion and its neurogenetic determinants. Here, we present the IMBA (individual maggot behaviour analyser) for analysing the behaviour of individual larvae within groups, reliably resolving individual identity across collisions. We use the IMBA to systematically describe the inter- and intra-individual variability in locomotion of wild-type animals, and how the variability is reduced by associative learning. We then report a novel locomotion phenotype of an adhesion GPCR mutant. We further investigated the modulation of locomotion across repeated activations of dopamine neurons in individual animals, and the transient backward locomotion induced by brief optogenetic activation of the brain-descending ‘mooncrawler’ neurons. In summary, the IMBA is an easy-to-use toolbox allowing an unprecedentedly rich view of the behaviour and its variability of individual larvae, with utility in multiple biomedical research contexts