Robustness of the biotic indicators used for classification of ecological status of lotic water bodies: A testing method when the data series are short

Successful implementation of the Water Framework Directive and achieving its objective of good ecological status of all water bodies depend on the power of the set of monitoring indicators to capture the change in the ecological status of aquatic systems. In this context, testing the robustness and sensitivity of ecological indicators currently used for assessing the status of lotic water bodies is instrumental for the adaptation and further development of assessment methods. This is also a prerequisite for an effective, context-based monitoring system and for improving the quality of the decision making for water bodies. This is particularly challenging in regions where the sets of indicators are under development, the data series are relatively short and data which addresses the individual error sources are lacking. Here we show that hierarchical clusters and ordination analysis provide appropriate tools with which the validity of the ecological status of water bodies set up based on biological multimetric monitoring indices in a small water basin could be tested. We hypothesize that robust and informative monitoring methods classify all water bodies belonging to a single ordination grouping in the same quality class (high, good, moderate, poor or bad). In our case study multimetric biological indicators failed to discriminate between the good and moderate ecological status. Community structure as well as water conductivity and nitrate load were primarily responsible for the observed difference between ordination groupings. Inconsistencies shown in our case study are likely to be induced by insufficient refinement of monitoring schemes and by the constraints existing in the data series and available metadata. We show that multiplication of indicators leads to discrepant interpretation and problematic application. Proposed ordination analysis proves to be a simple and useful tool to detect such discrepancies and support further progress in indicator development. Integrated and longer data and metadata series are needed to refine context-based monitoring methods.     

Osmotic stress decreases complexity underlying the electrophysiological dynamic in soybean

• Studies on plant electrophysiology are mostly focused on specific traits of single cells. Inspired by the complexity of the signalling network in plants, and by analogy with neurons in human brains, we sought evidence of high complexity in the electrical dynamics of plant signalling and a likely relationship with environmental cues.
• An EEG‐like standard protocol was adopted for high‐resolution measurements of the electrical signal in Glycine max seedlings. The signals were continuously recorded in the same plants before and after osmotic stimuli with a ?2 MPa mannitol solution. Non‐linear time series analyses methods were used as follows: auto‐correlation and cross‐correlation function, power spectra density function, and complexity of the time series estimated as Approximate Entropy (ApEn).
• Using Approximate Entropy analysis we found that the level of temporal complexity of the electrical signals was affected by the environmental conditions, decreasing when the plant was subjected to a low osmotic potential. Electrical spikes observed only after stimuli followed a power law distribution, which is indicative of scale invariance.
• Our results suggest that changes in complexity of the electrical signals could be associated with water stress conditions in plants. We hypothesised that the power law distribution of the spikes could be explained by a self‐organised critical state (SOC) after osmotic stress.

     

Evaluating the performance of benthic multi-metric indices across broad-scale environmental gradients

The usefulness of benthic multi-metric indices when assessing seafloor integrity across broad environmental gradients should be deliberated, as their lack of transparency might hide important sources of variation and fail to identify environmental change. This study compares the performance of two multi-metric indices; the Benthic Quality Index (BQI) and the Brackish water Benthic Index (BBI) between three sub-basins in the Baltic Sea. Both indices reflect the salinity-driven gradient in macroinvertebrate diversity and composition as well as changes in bottom water oxygen concentrations. The relative contribution of predictor variables for explaining index variation does, however, differ between sub-basins, resulting in the indices representing different aspects of the benthic community along the environmental gradient. This context-dependency is caused by inherent differences in benthic community characteristics between the sub-basins of the Baltic Sea, and how the communities are portrayed by the indices. An increased transparency of the importance of the different predictors for directing index values is needed for coherent classifications over broad environmental gradients, such as those occurring in large estuarine water bodies. Use of a weight of evidence table to combine multiple indicators would preserve transparency and be more likely to provide a robust assessment method that would detect seafloor degradation at an early stage.     

Rhodobacteraceae on the marine brown alga Fucus spiralis are abundant and show physiological adaptation to an epiphytic lifestyle

Macroalgae harbour specific microbial communities on their surface that have functions related to host health and defence. In this study, the bacterial biofilm of the marine brown alga Fucus spiralis was investigated using 16S rRNA gene amplicon-based analysis and isolation of bacteria. Rhodobacteraceae (Alphaproteobacteria) were the predominant family constituting 23% of the epibacterial community. At the genus level, Sulfitobacter, Loktanella, Octadecabacter and a previously undescribed cluster were most abundant, and together they comprised 89% of the Rhodobacteraceae. Supported by a specific PCR approach, 23 different Rhodobacteraceae-affiliated strains were isolated from the surface of F. spiralis, which belonged to 12 established and three new genera. For seven strains, closely related sequences were detected in the 16S rRNA gene dataset. Growth experiments with substrates known to be produced by Fucus spp. showed that all of them were consumed by at least three strains, and vitamin B₁₂ was produced by 70% of the isolates. Since growth of F. spiralis depends on B₁₂ supplementation, bacteria may provide the alga with this vitamin. Most strains produced siderophores, which can enhance algal growth under iron-deficient conditions. Inhibiting properties against other bacteria were only observed when F. spiralis material was present in the medium. Thus, the physiological properties of the isolates indicated adaption to an epiphytic lifestyle.     

Isolation,Culture and Long-Term Maintenance of Primary Mesencephalic Dopaminergic Neurons From Embryonic Rodent Brains

Degeneration of mesencephalic dopaminergic (mesDA) neurons is the pathological hallmark of Parkinson’s diseae. Study of the biological processes involved in physiological functions and vulnerability and death of these neurons is imparative to understanding the underlying causes and unraveling the cure for this common neurodegenerative disorder. Primary cultures of mesDA neurons provide a tool for investigation of the molecular, biochemical and electrophysiological properties, in order to understand the development, long-term survival and degeneration of these neurons during the course of disease. Here we present a detailed method for the isolation, culturing and maintenance of midbrain dopaminergic neurons from E12.5 mouse (or E14.5 rat) embryos. Optimized cell culture conditions in this protocol result in presence of axonal and dendritic projections, synaptic connections and other neuronal morphological properties, which make the cultures suitable for study of the physiological, cell biological and molecular characteristics of this neuronal population.     

Malaria-induced reduction of fecundity during the first gonotrophic cycle of Anopheles Stephensi mosquitoes

Abstract. Anopheles stephensi mosquitoes which had fed upon mice infected with Plasmodium yoelii nigeriensis malaria parasites produced significantly fewer eggs than mosquitoes fed on an uninfected mouse. Fecundity reduction was more pronounced when the bloodmeal contained malaria gametocytes and the mosquitoes developed oocysts. Egg production and haematin excretion were correlated for uninfected bloodfed mosquitoes; the presence of P.y. nigeriensis in the blood affected this relationship. Reduced fecundity was associated with a significant reduction of bloodmeal size (measured by haematin excretion) in mosquitoes which ingested gametocytaemic blood. The bloodmeal size in mosquitoes fed on parasitaemic blood without gametocytes was not significantly reduced. The use of haematin assays for determination of bloodmeal size in mosquitoes is discussed.     

N-phenyl ureidobenzenesulfonates,a novel class of promising human dihydroorotate dehydrogenase inhibitors

N-phenyl ureidobenzenesulfonates (PUB-SOs) is a new class of promising anticancer agents inducing replication stresses and cell cycle arrest in S-phase. However, the pharmacological target of PUB-SOs was still unidentified. Consequently, the objective of the present study was to identify and confirm the pharmacological target of the prototypical PUB-SO named 2-ethylphenyl 4-(3-ethylureido)benzenesulfonate (SFOM-0046) leading to the cell cycle arrest in S-phase. The antiproliferative and the cytotoxic activities of SFOM-0046 were characterized using the NCI-60 screening program and its fingerprint was analyzed by COMPARE algorithm. Then, human dihydroorotate dehydrogenase (hDHODH) colorimetric assay, uridine rescuing cell proliferation and molecular docking in the brequinar-binding site were performed. As a result, SFOM-0046 exhibited a mean antiproliferative activity of 3.5 μM in the NCI-60 screening program and evidenced that leukemia and colon cancer cell panels were more sensitive to SFOM-0046. COMPARE algorithm showed that the SFOM-0046 cytotoxic profile is equivalent to the ones of brequinar and dichloroallyl lawsone, two inhibitors of hDHODH. SFOM-0046 inhibited the hDHODH in the low nanomolar range (IC₅₀ = 72 nM) and uridine rescued the cell proliferation of HT-29, HT-1080, M21 and MCF-7 cancer cell lines in the presence of SFOM-0046. Finally, molecular docking showed a binding pose of SFOM-0046 interacting with Met43 and Phe62 present in the brequinar-binding site. In conclusion, PUB-SOs and notably SFOM-0046 are new small molecules hDHODH inhibitors triggering replication stresses and S-phase arrest.