590 Tiere (Zoologie)
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Petroleum products including crude oils and refined distillates are unique environmental pollutants consisting of thousands of compounds with varying physical-chemical properties and resulting toxicity for aquatic biota. Hence, for a reliable risk assessment individual petroleum product toxicity profiles are needed. Furthermore, the influence of oil spill response strategies like the application of chemical dispersants has to be implemented. The present study addressed the toxicity of water-accommodated fractions (WAFs) of two different oil types on fish early life stages on different biological organization levels in the laboratory model species Danio rerio. Experiments with a 3rd generation dispersant used in loading rated resembling the exposure in experiments with chemically dispersed oils were included, enabling a direct comparability of results. This approach is of high importance as especially the investigation of dispersant toxicity in relevant exposure concentrations is rather scarce. Zebrafish embryos were exposed to different WAFs shortly after and up to 120 hour post fertilization (hpf). Besides phenotypic effects including edema and spine deformations, reduced responses to dark stimuli, increased CYP1A activity and marginal AChE inhibition were observed in sublethal effect concentrations. Both oil types had varying strength of toxicity, which did not correlate with corresponding chemical analysis of target PAHs. Chemically dispersed oils induced stronger acute toxicity in zebrafish embryos compared to native (initial) oil exposure, which was further reflected by very low exposure concentrations for biomarker endpoints. Based on a comparison to the dispersant alone, a higher toxicity of dispersed oils was related to a combination of dispersant toxicity and an elevated crude oil compound bioavailability, due to dispersion-related partitioning kinetics. In contrast to LEWAF and CEWAF neither typical morphological effects nor mechanism-specific toxicity were observed for the dispersant alone, indicating narcosis as the responsible cause of effects.
In pursuit of food, hungry animals mobilize significant energy resources and overcome exhaustion and fear. How need and motivation control the decision to continue or change behavior is not understood. Using a single fly treadmill, we show that hungry flies persistently track a food odor and increase their effort over repeated trials in the absence of reward suggesting that need dominates negative experience. We further show that odor tracking is regulated by two mushroom body output neurons (MBONs) connecting the MB to the lateral horn. These MBONs, together with dopaminergic neurons and Dop1R2 signaling, control behavioral persistence. Conversely, an octopaminergic neuron, VPM4, which directly innervates one of the MBONs, acts as a brake on odor tracking by connecting feeding and olfaction. Together, our data suggest a function for the MB in internal state-dependent expression of behavior that can be suppressed by external inputs conveying a competing behavioral drive.
The sponge genus Latrunculia is a prolific source of discorhabdin type pyrroloiminoquinone alkaloids. In the continuation of our research interest into this genus, we studied the Antarctic deep-sea sponge Latrunculia biformis that showed potent in vitro anticancer activity. A targeted isolation process guided by bioactivity and molecular networking-based metabolomics yielded three known discorhabdins, (−)-discorhabdin L (1), (+)-discorhabdin A (2), (+)-discorhabdin Q (3), and three new discorhabdin analogs (−)-2-bromo-discorhabdin D (4), (−)-1-acetyl-discorhabdin L (5), and (+)-1-octacosatrienoyl-discorhabdin L (6) from the MeOH-soluble portion of the organic extract. The chemical structures of 1–6 were elucidated by extensive NMR, HR-ESIMS, FT-IR, [α]D, and ECD (Electronic Circular Dichroism) spectroscopy analyses. Compounds 1, 5, and 6 showed promising anticancer activity with IC50 values of 0.94, 2.71, and 34.0 µM, respectively. Compounds 1–6 and the enantiomer of 1 ((+)-discorhabdin L, 1e) were docked to the active sites of two anticancer targets, topoisomerase I-II and indoleamine 2,3-dioxygenase (IDO1), to reveal, for the first time, the binding potential of discorhabdins to these proteins. Compounds 5 and 6 are the first discorhabdin analogs with an ester function at C-1 and 6 is the first discorhabdin bearing a long-chain fatty acid at this position. This study confirms Latrunculia sponges to be excellent sources of chemically diverse discorhabdin alkaloids.
Microplastics (MP) are contaminants of emerging concern in aquatic ecosystems. While the number of studies is rapidly increasing, a comparison of the toxicity of MP and natural particulate matter is largely missing. In addition, research focusses on the impacts of hydrophobic chemicals sorbed to plastics. However, the interactive effects of MP and hydrophilic, dissolved chemicals remain largely unknown. Therefore, we conducted chronic toxicity studies with larvae of the freshwater dipteran Chironomus riparius exposed to unplasticised polyvinyl chloride MP (PVC-MP) as well as kaolin and diatomite as reference materials for 28 days. In addition, we investigated the effects of particles in combination with the neonicotinoid imidacloprid in a multiple-stressor experiment. High concentrations of kaolin positively affected the chironomids. In contrast, exposure to diatomite and PVC-MP reduced the emergence and mass of C. riparius. Likewise, the toxicity of imidacloprid was enhanced in the presence of PVC-MP and slightly decreased in the co-exposure with kaolin. Overall, parallel experiments and chemical analysis indicate that the toxicity of PVC-MP was not caused by leached or sorbed chemicals. Our study demonstrates that PVC-MP induce more severe effects than both natural particulate materials. However, the latter are not benign per se, as the case of diatomite highlights. Considering the high, environmentally irrelevant concentrations needed to induce adverse effects, C. riparius is insensitive to exposures to PVC-MP.
Flesh flies (Sarcophagidae) are necrophagous insects initially colonizing on a corpse. The species-specific developmental data of the flies collected from a death scene can be used to estimate the minimum postmortem interval (PMImin). Thus, the first crucial step is to correctly identify the fly species. Because of the high similarity among species of flesh flies, DNA-based identification is considered more favorable than morphology-based identification. In this study, we demonstrated the effectiveness of combined sequences (2216 to 2218 bp) of cytochrome c oxidase subunit I and II genes (COI and COII) for identification of the following 14 forensically important flesh fly species in Thailand: Boettcherisca nathani Lopes, Fengia ostindicae (Senior-White), Harpagophalla kempi (Senior-White), Liopygia ruficornis (Fabricius), Lioproctia pattoni (Senior-White), Lioproctia saprianovae (Pape & Bänziger), Parasarcophaga albiceps (Meigen), Parasarcophaga brevicornis (Ho), Parasarcophaga dux (Thomson), Parasarcophaga misera (Walker), Sarcorohdendorfia antilope (Böttcher), Sarcorohdendorfia inextricata (Walker), Sarcorohdendorfia seniorwhitei (Ho) and Seniorwhitea princeps (Wiedemann). Nucleotide variations of Thai flesh flies were evenly distributed throughout the COI-COII genes. Mean intra- and interspecific variations ranged from 0.00 to 0.96% and 5.22% to 12.31%, respectively. Using Best Match (BM) and Best Close Match (BCM) criteria, identification success for the combined genes was 100%, while the All Species Barcodes (ASB) criterion showed 76.74% success. Maximum Likelihood (ML) and Bayesian Inference (BI) phylogenetic analyses yielded similar tree topologies of monophyletic clades between species with very strong support values. The achieved sequences covering 14 forensically important flesh fly species including newly submitted sequences for B. nathani, F. ostindicae and S. seniorwhitei, can serve as a reliable reference database for further forensic entomological research in Thailand and in other areas where those species occur.
Background: Developmental biology relies to a large extent on the observation and comparison of phenotypic traits through time using high resolution microscopes. In this context, transparent model organisms such as the zebrafish Danio rerio in which developing tissues and organs can be easily observed and imaged using fluorescent proteins have become very popular. One limiting factor however is the acquisition of a sufficient amount of data, in standardized and reproducible conditions, to allow robust quantitative analysis. One way to improve this is by developing mounting methods to increase the number of embryos that can be imaged simultaneously in near-to-identical orientation.
Results: Here we present an improved mounting method allowing semi-automated and high-content imaging of zebrafish embryos. It is based on a 3D-printed stamp which is used to create a 2D coordinate system of multiple μ-wells in an agarose cast. Each μ-well models a negative of the average zebrafish embryo morphology between 22 and 96 h-post-fertilization. Due to this standardized and reproducible arrangement, it is possible to define a custom well plate in the respective imaging software that allows for a semi-automated imaging process. Furthermore, the improvement in Z-orientation significantly reduces post-processing and improves comparability of volumetric data while reducing light exposure and thus photo-bleaching and photo-toxicity, and improving signal-to-noise ratio (SNR).
Conclusions: We present here a new method that allows to standardize and improve mounting and imaging of embryos. The 3D-printed stamp creates a 2D coordinate system of μ-wells in an agarose cast thus standardizing specimen mounting and allowing high-content imaging of up to 44 live or mounted zebrafish embryos simultaneously in a semi-automated, well-plate like manner on inverted confocal microscopes. In summary, image data quality and acquisition efficiency (amount of data per time) are significantly improved. The latter might also be crucial when using the services of a microscopy facility.
Small-scale phenotypic differentiation along complex stream gradients in a non-native amphipod
(2019)
Background: Selective landscapes in rivers are made up by an array of selective forces that vary from source to downstream regions or between seasons, and local/temporal variation in fitness maxima can result in gradual spatio-temporal variation of phenotypic traits. This study aimed at establishing freshwater amphipods as future model organisms to study adaptive phenotypic diversification (evolutionary divergence and/or adaptive plasticity) along stream gradients.
Methods: We collected Gammarus roeselii from 16 sampling sites in the Rhine catchment during two consecutive seasons (summer and winter). Altogether, we dissected n = 1648 individuals and quantified key parameters related to morphological and life-history diversification, including naturally selected (e.g., gill surface areas) as well as primarily sexually selected traits (e.g., male antennae). Acknowledging the complexity of selective regimes in streams and the interrelated nature of selection factors, we assessed several abiotic (e.g., temperature, flow velocity) and biotic ecological parameters (e.g., conspecific densities, sex ratios) and condensed them into four principal components (PCs).
Results: Generalized least squares models revealed pronounced phenotypic differentiation in most of the traits investigated herein, and components of the stream gradient (PCs) explained parts of the observed differences. Depending on the trait under investigation, phenotypic differentiation could be ascribed to variation in abiotic conditions, anthropogenic disturbance (influx of thermally polluted water), or population parameters. For example, female fecundity showed altitudinal variation and decreased with increasing conspecific densities, while sexual dimorphism in the length of male antennae—used for mate finding and assessment—increased with increasing population densities and towards female-biased sex ratios.
Conclusions: We provide a comprehensive protocol for comparative analyses of intraspecific variation in life history traits in amphipods. Whether the observed phenotypic differentiation over small geographical distances reflects evolutionary divergence or plasticity (or both) remains to be investigated in future studies. Independent of the mechanisms involved, variation in several traits is likely to have consequences for ecosystem functions. For example, leaf-shredding in G. roeselii strongly depends on body size, which varied in dependence of several ecological parameters.
Description of Hemicordulia tuiwawai sp. nov. from Kadavu Island, Fiji (Odonata: Corduliidae)
(2019)
Hemicordulia tuiwawai sp. nov. (Odonata: Corduliidae) is described and diagnosed based on material collected from Kadavu Island, Fiji; holotype: Wainitayuki River about 750 m above Baidamudamu village, -19.0916, 178.1038; 37 m a.s.l., 06 June 2016, M. Marinov leg. This species is distinguished from its congeners in the field by the contrasting colouration – dark green metallic body with bright yellow spots on the synthorax and base of the abdomen. This pattern is comparable to H. pacifica Selys, 1871. However, Hemicordulia tuiwawai sp. nov. can be recognised by the larger size and unique shape of the caudal appendages and genital hamule (in males) and vulvar scale (in females).
Records of Odonata from the southwest of Sri Aman Division and the extreme east of Serian Division in Sarawak are presented. The sampled areas are interesting not only because they are poorly known for Odonata but also because many are just to the south and west of the Lupar Line which is a division between the ancient Sunda shelf and more recent geological formations. Differences between the odonate faunas on either side of the Lupar Line are discussed. Eightyfive species of Odonata were recorded during the surveys reported on. The single most notable record is that of Coeliccia southwelli Dow & Reels, 2011, which represents a considerable extension to the known range of this species. Other interesting records include Telosticta dupophila (Lieftinck, 1933), T. species cf longigaster Dow & Orr, 2012, Podolestes parvus Dow & Ngiam, 2019 and Heliogomphus species cf olivaceous Lieftinck, 1961. Variation in the markings of Stenagrion dubium (Laidlaw, 1912) across its range is discussed and a gene tree using the COI marker is presented to illustrate the high variability of this species in this marker. However the variability in COI does not appear to be correlated with other characters.
Odonatological results of a trip across the southern Far East of Russia, from nearly the border of North Korea to Khabarovsk from July 1st to 16th, 2014, are presented. In total, 50 species were recorded, including those with limited presence in Russia, such as Paracercion calamorum, P. hieroglyphicum, P. plagiosum (for this species the 3rd Russian locality is reported), Pseudocopera tokyoensis, Stylurus annulatus (2nd Russian locality), Sinictinogomphus clavatus; Trigomphus citimus, Macromia daimoji (3rd Russian locality), M. manchurica, Deielia phaon, Lyriothemis pachygastra (2nd Russian locality). For S. annulatus, M. manchurica and D. phaon the northernmost known localities in the world are reported. D. phaon, earlier reported from one locality in Russia, have been found in five localities in Primorye and for the first time reported for Khabarovskiy Kray in general and Bol'shekhekhtsirskiy State Nature Reserve in particular. A trend of mutual exclusion of two abundant Shaogomphus postocularis epophthalmus and S. schmidti is supposed: the lowermost Ussuri River / Amur River, respectively. Variation in Paracercion spp. and Macromia amphigena fraenata is discussed.
During four field trips in Georgia, Armenia and Azerbaijan from 2010 to 2018, the author collected data of a total of 55 species (see Tab. 2 in Appendix). This study provides first insights into new or rare species in this ecoregion. Ischnura fountaineae and Cordulia aenea were found for the first time in Armenia. We also highlight the rediscovery of some species that were mentioned in the older literature but had not been confirmed since. An autochthonous population of Lestes macrostigma was discovered in Azerbaijan sixteen years after the single previous record by Dumont (2004). Original information is provided on the distribution of some rare species encountered in these countries. Finally, the identification of a puzzling Cordulegaster sp. observed in south Armenia is discussed briefly.
The Odonata collection deposited at the Museum of Comparative Zoology (MCZ) includes specimens of 634 taxa labeled as types. Fifteen of these have been incorrectly labeled as types (pseudotypes) and eight are apparently lost, leaving a total of 611 types currently deposited at MCZ. From these, 489 represent primary namebearing types (syntype/s, holotype, lectotype and neotype), 21 are probable primary types, and 101 are secondary types (paratype/s, paralectotype/s).
A checklist of 49 damselfly species from 12 families (Odonata: Zygoptera) recorded from Kon Ka Kinh National Park is provided. A first description of the female Protosticta socculus Phan & Kompier, 2016, is given. Burmargiolestes cf. laidlawi Lieftinck, 1960 and three apparently new species, two Coeliccia and one Protosticta species, are recorded, all of which are to be described in the future.