Distribution patterns of the two genetic groups of Corbicula fluminea in a lotic-lentic system.

Differences in local habitat conditions are often implicated as drivers for morphological and genetic divergence in natural populations. However, there are still relatively few studies regarding how divergent habitats influence patterns for morphotypes and genetic lineages in aquatic invertebrates. In this study, we explored the morphological patterns, genetic divergence, and distributions of a bivalve, Corbicula fluminea, in a lotic-lentic system. Sampling locations included lotic, ecotone, and lentic habitats. First, we found two lineages (Lineages A and B) with significant genetic divergence that primarily corresponded to two morphotypes (Morphs D and C) of C. fluminea. Lineage A consisted of 88.68% Morph D (shell sculpture: 8-14 ridges/cmsh) and 11.32% Morph C (shell sculpture: 15 ridges/cmsh) individuals and had genetic similarity to invasive populations. Lineage B consisted of only Morph C (shell sculpture: 15-23 ridges/cmsh). Second, we revealed clear effects of habitat on the spatial distribution patterns for the two lineages of C. fluminea. Lineage A was dominant in lotic habitats, with a significantly higher density than that of Lineage B in these locations. Lineage B was dominant in lentic habitats. However, both lineages had their highest densities in the ecotone habitat, without clear dominance and no significant difference in density between groups. Individuals of Lineages A and B are different in shell morphology, which may be related to a benefit trade-off between shell shapes that allow for rapid burrowing and holding position in different flow conditions. The distribution patterns indicate that Lineages A and B may not prefer uniquely lotic and lentic habitats, but each lineage is more tolerant to one habitat type, respectively. Generally, our study established a correlation among morphotypes, lineages, and different habitats for C. fluminea along a lotic-lentic gradient system, which has important implementations for fisheries management units and for understanding the role of habitat preference for this species in monitoring for pioneer dispersal in invasive species management.

Investigations of Fish Assemblages Using Two Methods in Three Terminal Reservoirs of the East Route of South-to-North Water Transfer Project, China.

The terminal reservoirs of water transfer projects directly supply water for domestic, agricultural, and industrial applications, and the water quality of these reservoirs produce crucial effects on the achievement of project targets. Typically, fish assemblages are monitored as indicators of reservoir water quality, and can also be regulated for its improvement. In the present study, we compared traditional fish landing (TFL) and environmental DNA (eDNA) metabarcoding methods for monitoring fish assemblages in three terminal reservoirs of the East Route of the South-to-North Water Transfer Project, China. Results of TFL and eDNA showed similar assemblage structures and patterns of diversity and spatial distribution with obvious differences in fish composition across three examined reservoirs. Demersal and small fish were dominant in all reservoirs. In addition, a strong association between water transfer distance and assemblages and distribution of non-native fish was found. Our findings highlight the necessity of the fish assemblage monitoring and managing for water quality and revealed the impact of water diversion distance on the structure of fish assemblages and dispersal of alien species along the water transfer project.

Interpopulation trophic niches and ontogenetic shifts of a mangrove fish predator.

Fish trophic niches reflect important ecological interactions and provide insight into the structure of mangrove food webs. Few studies have been conducted in mangrove fish predators to investigate interpopulation trophic niches and ontogenetic shifts. Using stable isotope analysis and two complementary approaches, the authors investigated trophic niche patterns within and between two ontogenetic groups (juveniles and sub-adults) of a generalist predator (Acentrogobius viridipunctatus) in four mangroves with heterogeneous environmental conditions (e.g., tidal regimes, salinity fluctuations and mangrove tree community). The authors hypothesized that the trophic niche between populations would vary regionally and trophic position would increase consistently from juvenile to sub-adult stages. The results revealed that both δ13 C and δ15 N values varied greatly across populations and between ontogenetic groups, and complex spatio-ontogenetic variations were expressed by Layman's metrics. They also found some niche separation in space, which is most likely related to resource availability in spatially diverse ecosystems. In addition, trophic niche position increased consistently from juveniles to sub-adults, indicating ontogenetic feeding shifts. The isotopic plasticity index and Fulton's condition index also showed significant spatial-ontogenetic variation, which is consistent with optimal foraging theory. The findings highlight that trophic plasticity has a high adaptive value for mangrove fish predators in dynamic ecosystems.

A Retro-biosynthesis-Based Route to Generate Pinene-Derived Polyesters.

Significantly increased production of biobased polymers is a prerequisite to replace petroleum-based materials towards reaching a circular bioeconomy. However, many renewable building blocks from wood and other plant material are not directly amenable for polymerization, due to their inert backbones and/or lack of functional group compatibility with the desired polymerization type. Based on a retro-biosynthetic analysis of polyesters, a chemoenzymatic route from (-)-α-pinene towards a verbanone-based lactone, which is further used in ring-opening polymerization, is presented. Generated pinene-derived polyesters showed elevated degradation and glass transition temperatures, compared with poly(ϵ-decalactone), which lacks a ring structure in its backbone. Semirational enzyme engineering of the cyclohexanone monooxygenase from Acinetobacter calcoaceticus enabled the biosynthesis of the key lactone intermediate for the targeted polyester. As a proof of principle, one enzyme variant identified from screening in a microtiter plate was used in biocatalytic upscaling, which afforded the bicyclic lactone in 39 % conversion in shake flask scale reactions.

The potential colonization histories of Opsariichthys bidens (Cyprinidae) in China using Bayesian binary MCMC analysis.

Vicariance and/or long-distance dispersal shape the distribution patterns of many extant taxa, and orogenesis and/or climate fluctuations are key factors that drive the events of vicariance and/or dispersal. In this study, we yielded biogeographical inferences from Bayesian binary MCMC (BBM) analysis to explore the potential colonization histories of Opsariichthys bidens in China and to identify potential factors responsible for the colonization histories. Many vicariance and dispersal events were identified. The results suggested that O. bidens seemed to have originated from the Yangtze River and/or the Pearl River and experienced a Yangtze River-Pearl River split at 7.04 million years ago (Ma). BBM analysis revealed that the Pearl River populations had undergone expansions to the Hainan drainages, the Lancangjiang River (upper Mekong) and the Nanpanjiang River (upper branch of the Pearl River) at 0.74 Ma. Meanwhile, the Yangtze River populations expanded to the northeastern drainages during the Early Pleistocene. Subsequently, the northeastern drainages dispersed to the Yellow River during the Middle Pleistocene. More recently, the northeastern drainage populations also dispersed to the Huaihe River and back to the Yangtze River. A portion of the Pearl River populations originated from the Yangtze River dispersed to the Jiulongjiang River during the Middle Pleistocene. These time scales fit well with the uplift of the Qinghai-Tibet Plateau and Pleistocene glacial cycles, indicating the two factors played vital roles in shaping the colonization histories of O. bidens.

Template-Assisted Enzymatic Synthesis of Oligopeptides from a Polylactide Chain.

Peptides are often attached to polymer materials, as bioactive components, for the control of interactions between the material and its surrounding proteins and cells. However, synthesizing peptides and attaching them to polymers can be challenging and laborious. Herein, we describe the grafting of oligopeptides to an aliphatic polyester, using a one-step chemo-enzymatic synthesis with papain as the biocatalyst. To enable enzyme-mediated functionalization of the polyester, ethyl hept-6-enoylalaninate (grafter) was synthesized and attached to polylactide chains using thiol-ene click reactions. The oligopeptides were grafted onto the polylactide chains using two different synthetic routes: the grafting from strategy, in which the grafter was attached to the polyester prior to oligopeptide synthesis, or the grafting to strategy, in which oligopeptides were synthesized on the grafter first, then attached to the polymer chain. The final products were analyzed and their structures were confirmed using nuclear magnetic resonance (NMR). The peptide attachment was evaluated using size exclusion chromatography (SEC), contact angle measurement and energy-dispersive X-ray spectroscopy-scanning electron microscopy (EDS-SEM). Furthermore, the mechanistic aspects of the synthesis of the oligopeptides on the grafter were studied using molecular dynamics (MD) simulations. The simulation revealed that hydrogen bonding (between the P1 amide nitrogen of the grafter backbone and the carbonyl oxygen of D158 in the papain) maintain the grafter in a productive conformation to stabilize the transition state of nitrogen inversion, a key step of the biocatalytic mechanism. Apart from being biologically relevant, both experimental and computational results suggest that the designed grafter is a good template for initiating chemo-enzymatic synthesis. The results also showed that the grafting to strategy was more successful compared to the grafting from strategy. Overall, a successful synthesis of predefined peptide functionalized polylactide was prepared, where the oligopeptides were grafted in an easy, time efficient, and environmentally friendly way.

Left and right atrial feature tracking in acute myocarditis: A feasibility study.

PURPOSE: The present study aims at evaluating the feasibility and reproducibility of cardiac magnetic resonance (CMR) feature tracking (FT) derived strain and strain rate (SR) parameters of the left and right atrium (LA, RA) in patients with acute myocarditis as well as their potential to detect diastolic dysfunction. In addition, the diagnostic value of LA and RA strain parameters in the setting of acute myocarditis is investigated. METHODS: CMR cine data of 30 patients with CMR-positive acute myocarditis were retrospectively analyzed. 25 age- and gender-matched healthy individuals served as a control. Analysis of longitudinal strain and SR of both atria was performed in two long-axis views using a dedicated FT-software. LA and RA deformation was analyzed including reservoir function (total strain [εs], peak positive SR [SRs]), conduit function (passive strain [εe], peak early negative SR [SRe]) and booster pump function (active strain [εa], peak late negative SR [SRa]). Intra- and inter-observer reproducibility was assessed for all strain and SR parameters using Bland-Altman analyses, intra-class correlation coefficients (ICCs) and coefficients of variation (CV). RESULTS: FT analyses of both atria were feasible in all patients and controls. Reproducibility was good for reservoir and conduit function parameters and moderate for booster pump function parameters. Myocarditis patients demonstrated an impaired LA reservoir and conduit function when compared to healthy controls (LA εs: 32±17 vs. 46±13, p=0.019; LA SRs: 1.5±0.5 vs. 1.8±0.5, p=0.117; LA SRe: -1.3±0.5 vs. -1.9±0.5, p<0.001), while LA booster pump function was preserved. In logistic regression and ROC-analyses, LA SRe proved to be the best independent predictor of acute myocarditis (AUC 0.80), and using LA SRe with a cut-off of -1.6s-1 resulted in a diagnostic sensitivity of 83% and a specificity of 80%. Changes in RA phasic function parameters showed a tendency to parallel those of the LA and showed no additional effect with respect to the diagnostic potential in acute myocarditis. CONCLUSIONS: Myocarditis patients exhibit an impaired atrial reservoir and conduit function, what might be indicative of ventricular diastolic dysfunction. LA SRe was the best predictor for the presence of acute myocarditis in our study, pointing towards the discriminative power of atrial strain analysis in the CMR-based diagnosis of acute myocarditis.

Intra- and inter-observer reproducibility of global and regional magnetic resonance feature tracking derived strain parameters of the left and right ventricle.

OBJECTIVES: To investigate the reproducibility of regional and global strain and strain rate (SR) parameters of both ventricles and to determine sample sizes for all investigated strain and SR parameters in order to generate a practical reference for future studies. MATERIALS AND METHODS: The study population consisted of 20 healthy individuals and 20 patients with acute myocarditis. Cine sequences in three horizontal long axis views and a stack of short axis views covering the entire left and right ventricle (LV, RV) were retrospectively analysed using a dedicated feature tracking (FT) software algorithm (TOMTEC). For intra-observer analysis, one observer analysed CMR images of all patients and volunteers twice. For inter-observer analysis, three additional blinded observers analysed the same datasets once. Intra- and inter-observer reproducibility were tested in all patients and controls using Bland-Altman analyses, intra-class correlation coefficients (ICCs) and coefficients of variation. RESULTS: Intra-observer reproducibility of global LV strain and SR parameters was excellent (range of ICCs: 0.81-1.00), the only exception being global radial SR with a poor reproducibility (ICC 0.23). On a regional level, basal and midventricular strain and SR parameters were more reproducible when compared to apical parameters. Inter-observer reproducibility of all LV parameters was slightly lower than intra-observer reproducibility, yet still good to excellent for all global and regional longitudinal and circumferential strain and SR parameters (range of ICCs: 0.66-0.93). Similar to the LV, all global RV longitudinal and circumferential strain and SR parameters showed an excellent reproducibility, (range of ICCs: 0.75-0.97). Radial strain and SR parameters were less reproducible in the LV as well as in the RV when compared to circumferential or longitudinal parameters. CONCLUSION: CMR FT using the TOMTEC algorithm is highly reproducible in health and disease in both, the LV and RV on a global and regional level. The only exceptions are radial strain and SR parameters, which should be used with caution within clinical studies. The sample sizes estimated on the basis of the present study might serve as a reference during the planning of future FT studies.

Ptaquiloside in bracken spores from Britain.

Secondary metabolites from bracken fern (Pteridium aquilinum (L.) Kuhn) are suspected of causing cancer in humans. The main carcinogen is the highly water-soluble norsesquiterpene glucoside ptaquiloside, which may be ingested by humans through food, e.g. via contaminated water, meat or milk. It has been postulated that carcinogens could also be ingested through breathing air containing bracken spores. Ptaquiloside has not previously been identified in bracken spores. The aim of the study was to determine whether ptaquiloside is present in bracken spores, and if so, to estimate its content in a collection of spores from Britain. Ptaquiloside was present in all samples, with a maximum of 29 µg g(-1), which is very low compared to other parts of the fern. Considering the low abundance of spores in breathing air under normal conditions, this exposure route is likely to be secondary to milk or drinking water.

Quantitative characterization of gold nanoparticles by field-flow fractionation coupled online with light scattering detection and inductively coupled plasma mass spectrometry.

An analytical platform coupling asymmetric flow field-flow fractionation (AF(4)) with multiangle light scattering (MALS), dynamic light scattering (DLS), and inductively coupled plasma mass spectrometry (ICPMS) was established and used for separation and quantitative determination of size and mass concentration of nanoparticles (NPs) in aqueous suspension. Mixtures of three polystyrene (PS) NPs between 20 and 100 nm in diameter and mixtures of three gold (Au) NPs between 10 and 60 nm in diameter were separated by AF(4). The geometric diameters of the separated PS NPs and the hydrodynamic diameters of the Au and PS NPs were determined online by MALS and DLS, respectively. The three separated Au NPs were quantified by ICPMS and recovered at 50-95% of the injected masses, which ranged between approximately 8-80 ng of each nanoparticle size. Au NPs adhering to the membrane in the separation channel was found to be a major cause for incomplete recoveries. The lower limit of detection (LOD) ranged between 0.02 ng Au and 0.4 ng Au, with increasing LOD by increasing nanoparticle diameter. The analytical platform was applied to characterization of Au NPs in livers of rats, which were dosed with 10 nm, 60 nm, or a mixture of 10 and 60 nm nanoparticles by intravenous injection. The homogenized livers were solubilized in tetramethylammonium hydroxide (TMAH), and the recovery of Au NPs from the livers amounted to 86-123% of their total Au content. In spite of successful stabilization with bovine serum albumin even in alkaline medium, separation of the Au NPs by AF(4) was not possible due to association with undissolved remains of the alkali-treated liver tissues as demonstrated by electron microscopy images.

Quantitative HPLC-ICP-MS analysis of antimony redox speciation in complex sample matrices: new insights into the Sb-chemistry causing poor chromatographic recoveries.

In solution antimony exists either in the pentavalent or trivalent oxidation state. As Sb(III) is more toxic than Sb(V), it is important to be able to perform a quantitative speciation analysis of Sb's oxidation state. The most commonly applied chromatographic methods used for this redox speciation analysis do, however, often show a low chromatographic Sb recovery when samples of environmental or biological origin are analysed. In this study we explored basal chemistry of antimony and found that formation of macromolecules, presumably oligomeric and polymeric Sb(V) species, is the primary cause of low chromatographic recoveries. A combination of HPLC-ICP-MS, AFFF-ICP-MS and spin-filtration was applied for analysis of model compounds and biological samples. Quantitative chromatographic Sb redox speciation analysis was possible by acidic hydrolysis of the antimony polymers prior to analysis. Sample treatment procedures were studied and the optimum solution was acidic hydrolysis by 1 M HCl in the presence of chelating ligands (EDTA, citrate), which stabilise the trivalent oxidation state of Sb.

Genotoxicity of unmodified and organo-modified montmorillonite.

The natural clay mineral montmorillonite (Cloisite) Na+) and an organo-modified montmorillonite (Cloisite 30B) were investigated for genotoxic potential as crude suspensions and as suspensions filtrated through a 0.2-microm pore-size filter to remove particles above the nanometre range. Filtered and unfiltered water suspensions of both clays did not induce mutations in the Salmonella/microsome assay at concentrations up to 141microg/ml of the crude clay, using the tester strains TA98 and TA100. Filtered and unfiltered Cloisite) Na+ suspensions in culture medium did not induce DNA strand-breaks in Caco-2 cells after 24h of exposure, as tested in the alkaline comet assay. However, both the filtered and the unfiltered samples of Cloisite 30B induced DNA strand-breaks in a concentration-dependent manner and the two highest test concentrations produced statistically significantly different results from those seen with control samples (p<0.01 and p<0.001) and (p<0.05 and p<0.01), respectively. The unfiltered samples were tested up to concentrations of 170microg/ml and the filtered samples up to 216microg/ml before filtration. When tested in the same concentration range as used in the comet assay, none of the clays produced ROS in a cell-free test system (the DCFH-DA assay). Inductively coupled plasma mass-spectrometry (ICP-MS) was used to detect clay particles in the filtered samples using aluminium as a tracer element characteristic to clay. The results indicated that clay particles were absent in the filtered samples, which was independently confirmed by dynamic light-scattering measurements. Detection and identification of free quaternary ammonium modifier in the filtered sample was carried out by HPLC-Q-TOF/MS and revealed a total concentration of a mixture of quaternary ammonium analogues of 1.57microg/ml. These findings suggest that the genotoxicity of organo-modified montmorillonite was caused by the organo-modifier. The detected organo-modifier mixture was synthesized and comet-assay results showed that the genotoxic potency of this synthesized organo-modifier was in the same order of magnitude at equimolar concentrations of organo-modifier in filtrated Cloisite) 30B suspensions, and could therefore at least partly explain the genotoxic effect of Cloisite) 30B.

Genotoxic activity and inhibition of soil respiration by ptaquiloside, a bracken fern carcinogen.

Ptaquiloside (PTA) is a natural toxin produced by bracken (Pteridium aquilinum [L.] Kuhn). Assessment of PTA toxicity is needed because PTA deposited from bracken to soil may leach to surface and groundwater. Inhibition of soil respiration and genotoxic activity of PTA was determined by a soil microbial carbon transformation test and an umu test, respectively. In the carbon transformation test, sandy loam soil was incubated at five different initial concentrations of PTA for a period of 28 d, after which glucose was added and respiration measured for 12 consecutive hours. The tests were performed at 20 degrees C and soil moisture content of approximately 15%. For soil material sampled in the autumn, initial PTA concentrations ranging from 0.008 to 40.6 microg PTA/g dry soil were tested. From fitting of data by a sigmoidal function, a 10% effect dose (ED10) was estimated to 13 microg PTA/ g dry soil, with an upper 95% confidence limit of 43 microg PTA/g dry soil and a 95% lower confidence limit of -infinity microg PTA/g dry soil. For soil material sampled in late winter, initial PTA concentrations ranging from 1.56 to 212 microg PTA/g dry soil were tested, resulting in an ED10 value of 55 microg PTA/g dry soil, with an upper 95% confidence limit of 70 microg PTA/g dry soil and a 95% lower confidence limit of 40 microg PTA/g dry soil. The genotoxic activity of PTA was determined using the umu test without and with metabolic activation (addition of S9 rat liver homogenate). In tests with addition of S9, the induction ratio exceeded the critical ratio of 1.5 at a PTA concentration of 46 +/- 16 microg/ml and, in tests without S9, the critical ratio was exceeded at a PTA concentration of 279 +/- 22 microg/ml. The genotoxicity of PTA is comparable to that of quercetin, another bracken constituent. The toxicity of PTA toward microorganisms prolongs the persistence of PTA in terrestrial environments, increasing the risk of PTA leaching to drainage and groundwater.

Let's face the music: a behavioral and electrophysiological exploration of score reading.

This experiment was carried out to determine whether reading diatonic violations in a musical score elicits similar endogenous ERP components when hearing such violations in the auditory modality. In the behavioral study, musicians were visually presented with 120 scores of familiar musical pieces, half of which contained a diatonic violation. The score was presented in a measure-by-measure manner. Self-paced reading was significantly delayed for measures containing a violation, indicating that sight reading a violation requires additional effort. In the ERP study, the musical phrases were presented in a "RSVP"-like manner. We predicted that diatonic violations would elicit a late positive component. However, the ERP associated with the measure where a violation was presented showed a negativity instead. The negativity started around 100 ms and lasted for the entire recording period. This long-lasting negativity encompassed at least three distinct effects that were possibly related to violation detection, working memory processing, and a further integration/interpretation process.

Effects of musical expertise on the early right anterior negativity: an event-related brain potential study.

Event-related brain potentials in response to harmonically inappropriate chords were compared for musical experts and novices. Similar to previous studies, these chords elicited an early right anterior negativity (ERAN). The amplitude of the ERAN was clearly larger for musical experts than for novices, presumably because experts had more specific musical expectancies than novices. Chords with a physically deviant timbre elicited a mismatch negativity that did not differentiate the groups, indicating that the larger ERAN in experts was not due to a general enhanced auditory sensitivity. The ERAN reflects fast and automatic neural mechanisms that process complex musical (music-syntactic) irregularities, and the present results indicate that these mechanisms can be modulated by expertise.