Search

The study of distribution and dispersal of invasive fishes is challenging during the early stages of invasion. Quantification of trace elements incorporated into fish hard parts represents an innovative technique for this task. Otolith chemistry has been used to describe fish stock structure, migratory behaviour and to support the management of several species. We used otolith chemistry to study the dispersal and population structure of tench (Tinca tinca), an invader in the St. Lawrence River. Tench movements throughout the invaded portion of the system were reconstructed using a Random Forests algorithm. The results showed that, despite the presumed limited dispersal capacity of the species, tench are capable of extensive migratory movements (up to 250 km). The variability in migratory patterns among individuals, including both short- and long-distance movements, supports a stratified diffusion. Such a strategy may explain the successful invasion of tench in the St. Lawrence River ecosystem. Our study represents a flexible framework for the study of tench ecology in its invaded and native range, as well as for other freshwater invasive fishes. [ABSTRACT FROM AUTHOR]

Typified by heterogeneous habitats, large rivers host diversified communities throughout their course. As the spatial organisation of fish communities within these ecosystems remains little studied, longitudinal gradients and spatial heterogeneities of fish diversity were analysed in the large temperate St. Lawrence River, Canada. We used two distinct datasets obtained from either seine nets or gillnets from governmental standardised fish surveys (1995–2012) consisting of a total of 299,662 individuals from 76 fish species captured in 1,051 sites. Results from diversity indices and multivariate analysis revealed a gradual downstream increase in taxonomic diversity, and a gradual change of the community structure along the river. In addition, we observed different fish communities within fluvial lakes and corridors and found significant differences in fish community structure between opposite shores. The fish communities described along the river using seine nets are spatially more heterogeneous than when described using gillnets. This discrepancy is likely resulting both from the more mobile species targeted by gillnets and sampling sites located farther from the shallower shoreline habitat targeted by seine nets. The organisation of fish communities stresses the need to implement science-based policies and actions to preserve biodiversity and restore communities distributed over large heterogeneous ecosystems. [ABSTRACT FROM AUTHOR]

Abstract: Nimesulide, a COX-2 preferential inhibitor with a favorable gastric and cardiovascular safety profile, was responsible for some cases of acute liver failure attributed to the nitrobenzene ring. A series of analogs of nimesulide resulting from isosteric replacement of the nitrobenzene ring by the pyridine nucleus, was synthesized and their ability to inhibit both cyclooxygenases (COXs) isoforms was evaluated in vitro using a human whole blood model. Compounds 19c, 23b and 23c displayed an important inhibitory activity associated to a COX-2/COX-1 selectivity ratio similar to or higher than that of celecoxib. The anti-inflammatory activity and the ability of several compounds to decrease leukocyte infiltration were further evaluated in vivo in a model of a λ carrageenan-induced pleurisy. Plasma assays were performed on blood samples collected from rats and allowed us to identify the 4-position of the phenyl ring as a major metabolism site explaining the occasionally observed lack of correlation between in vitro and in vivo results. [Copyright &y& Elsevier]

Since the early 1950s, several species of salmonids have been introduced more or less successfully in the Kerguelen Islands, a 7,215 km² archipelago located in the Southern Ocean (49°S, 70°E) and previously devoid of any freshwater fish. The aim of this work was to establish a documented chronicle of these events from available archives, to better understand the causes of the colonization failure or success for the different species. The history that emerged from the analysis of the archives appeared much more complex than previously published. Stocks of various origins were used, and numerous attempts were made at different sites involving variable numbers of fish released at different life stages. Between 1951 and 1991, 22 importation attempts took place, involving about 2 million individuals. Of the 8 species introduced ( Salmo trutta, S. salar, Oncorhynchus mykiss, O. tshawytscha, O. kisutch, Salvelinus namaycush, S. fontinalis and S. alpinus), only 3 failed to establish local populations ( O. mykiss, O. tshawytscha and S. namaycush). Overall, 23 watersheds were stocked. At present, 45 watersheds are colonized by one or several species. S. trutta, S. fontinalis, S. alpinus and O. kisutch were capable of migrating toward new habitats. The brown trout ( S. trutta) was the only species to colonize a large number of watersheds (32 in about 10 generations). Its success can be explained by the diversity of origins, the number and importance of introduction and transfer attempts, the diversity of release sites and the peculiarities of its life cycle. [ABSTRACT FROM AUTHOR]

Abstract: The structure of doubly protonated vancomycin antibiotics with its cell-wall precursor analogue Ac2 LKDADA has been investigated in the gas phase through a combined laser spectroscopy, ion mobility and theoretical modeling approach. Replica-exchange molecular dynamics simulations using the Amber99 force field were performed to explore the potential energy landscape of isolated vancomycin ions, as well as the different binding sites with the receptor. Among the low-energy conformers found, those with a calculated diffusion cross-section consistent with ion mobility experiments were selected for further optimization, and their IR spectra were simulated using a hybrid quantum mechanics/semi-empirical (QM/SE) method at the DFT/B3LYP/6-31g(d):AM1 level. Both theoretical and experimental findings provide strong evidence that the native structure of the complex is not preserved in vacuo for the doubly protonated species. [ABSTRACT FROM AUTHOR]

Aim Similar regimes of selection in different geographical settings can deterministically produce similar adaptive morphologies. We tested the hypothesis that the evolutionary trajectories of fish in upwelling zones can be altered by biogeographic contingencies in the biological and physical environment. Location Eastern Pacific and western Atlantic oceans. Methods We estimated phylogenetic relationships among eastern Pacific temperate anchovies (genus Engraulis) and tropical anchovies (genus Cetengraulis) with neighbour-joining and Bayesian tree analysis of a 521-bp segment of mitochondrial DNA cytochrome b. Available sequences for five additional engraulid taxa were included to establish polarity of the tree. Bayesian estimates (BEAST) of time to most recent common ancestor (TMRCA) for the nodes in the phylogeny were calibrated with divergence between Cetengraulis edentulus and Cetengraulis mysticetus precipitated by the rise of the Panama Isthmus 2.8–3.2 Ma. Results Neighbour-joining and Bayesian trees indicate that South American Engraulis anchoita (Argentina) and Engraulis ringens (Chile) together are basal sister taxa to the California anchovy ( Engraulis mordax) and Old World anchovies ( Engraulis japonicas, Engraulis australis, Engraulis capensis and Engraulis encrasicolus). The two tropical species of Cetengraulis are sister-taxa to Californian E. mordax, even though their phenotypes and ecologies differ markedly. A relaxed molecular clock indicates a TMRCA between Californian E. mordax and Cetengraulis at about 4.2 Ma (3.0–6.3 Ma 95% highest probability density). Main conclusions The TMRCA between the California anchovy, E. mordax, and tropical Cetengraulis coincides with the formation of the Gulf of California, which provided opportunities for allopatric isolation during climate oscillations. Mid-Pliocene warming (3.1–2.9 Ma) may have trapped ancestors of Cetengraulis in the Gulf of California, where they evolved digestive tract morphologies to exploit inshore tropical habitats with low plankton productivities. While populations of several other temperate fishes have become isolated in the Gulf of California, few of these derived species show strong adaptive shifts from temperate sister taxa or range expansions into the tropical provinces of the western Atlantic and eastern Pacific. [ABSTRACT FROM AUTHOR]

Abstract: The putative dopaminergic (DA) neurons intrinsic to the human striatum were studied by applying immunofluorescence and quantitative methods to postmortem tissue from seven normal individuals. Stringent morphological and chemical criteria were used to identify striatal DA neurons, including immunostaining for tyrosine hydroxylase, DA transporter and neuronal nuclear protein. The DA neurons were scattered throughout the striatum, but abounded particularly in its ventral portion. Frequency distribution of surface areas of DA cell bodies reveals that the most frequent DA neurons (=58.0%, S.D.=12.8%) had a medium-sized (≉200±15μm2) perikaryon with 3–5 varicose dendrites, whereas others (=35.5%, S.D.=14.0%) had a smaller (≉140±15μm2) perikaryon with 3–4 varicose dendrites. There was a small number (=6.5%, S.D.=8.5%) of larger DA neurons (209–584μm2) with spiny dendrites and a few TH-immunoreactive cells displaying mixed neuron-glia morphology. Despite significant inter-individual variations in neuron density, the human striatum (mean volume of 8.76cm3) harbored a mean of 331.9 DA neurons (S.D.=199.2). A prolific zone, containing about 3000 cells, occurred in the ventral striatum in two brains. The addition of these cells would increase by about 10 times the total number of striatal DA neurons, which should not be confounded with segments of nigrostriatal DA fibers that displayed large (8–12μm) varicosities and looked like small bipolar neurons. The function of striatal DA neurons is unknown but the fact that their number increases markedly following lesion of nigral DA input or administration of various growth factors, opens up new therapeutic avenues for treatment of Parkinson''s disease. [Copyright &y& Elsevier]

Part of the life cycle of several fish species includes important salinity changes, as is the case for the sea bass (Dicentrarchus labrax) or the Atlantic salmon (Salmo salar). Salmo salar juveniles migrate downstream from their spawning sites to reach seawater, where they grow and become sexually mature. The process of preparation enabling juveniles to migrate downstream and physiologically adapt to seawater is called smoltification. Daily and seasonal variations of photoperiod and temperature play a role in defining the timing of smoltification, which may take weeks to months, depending on the river length and latitude. Smoltification is characterised by a series of biochemical, physiological and behavioural changes within the neuroendocrine axis. This review discusses the current knowledge and gaps related to the neuroendocrine mechanisms that mediate the effects of light and temperature on smoltification. Studies performed in S. salar and other salmonids, as well as in other species undergoing important salinity changes, are reviewed, and a particular emphasis is given to the pineal hormone melatonin and its possible role in osmoregulation. The daily and annual variations of plasma melatonin levels reflect corresponding changes in external photoperiod and temperature, which suggests that the hormonal time‐keeper melatonin might contribute to controlling smoltification. Here, we review studies on (i) the impact of pinealectomy and/or melatonin administration on smoltification; (ii) melatonin interactions with hormones involved in osmoregulation (e.g., prolactin, growth hormone and cortisol); (iii) the presence of melatonin receptors in tissues involved in osmoregulation; and (iv) the impacts of salinity changes on melatonin receptors and circulating melatonin levels. Altogether, these studies show evidence indicating that melatonin interacts with the neuroendocrine pathways controlling smoltification, although more information is needed to clearly decipher its mechanisms of action. [ABSTRACT FROM AUTHOR]

A growing number of studies have been investigating the influence of contemporary environmental factors on population genetic structure, but few have addressed the issue of spatial patterns in the variable intensity of factors influencing the extent of population structure, and particularly so in aquatic ecosystems. In this study, we document the landscape genetics of northern pike ( Esox lucius), based on the analysis of nearly 3000 individuals from 40 sampling sites using 22 microsatellites along the Lake Ontario - St. Lawrence River system (750 km) that locally presents diverse degrees of interannual water level variation. Genetic structure was globally very weak ( FST = 0.0208) but spatially variable with mean level of differentiation in the upstream section of the studied area being threefold higher ( FST = 0.0297) than observed in the downstream sector ( FST = 0.0100). Beside interannual water level fluctuation, 19 additional variables were considered and a multiple regression on distance matrices model ( R2 = 0.6397, P < 0.001) revealed that water masses ( b = 0.3617, P < 0.001) and man-made dams ( b = 0.4852, P < 0.005) reduced genetic connectivity. Local level of interannual water level stability was positively associated to the extent of genetic differentiation ( b = 0.3499, P < 0.05). As water level variation impacts on yearly quality and localization of spawning habitats, our study illustrates how temporal variation in local habitat availability, caused by interannual water level fluctuations, may locally decrease population genetic structure by forcing fish to move over longer distances to find suitable habitat. This study thus represents one of the rare examples of how environmental fluctuations may influence spatial variation in the extent of population genetic structure within a given species. [ABSTRACT FROM AUTHOR]

The gas-phase structures of doubly and triply protonated Amyloid-β 12-28 peptides have been investigated through the combination of ion mobility (IM), electron capture dissociation (ECD) mass spectrometry, and infrared multi-photon dissociation (IRMPD) spectroscopy together with theoretical modeling. Replica-exchange molecular dynamics simulations were conducted to explore the conformational space of these protonated peptides, from which several classes of structures were found. Among the low-lying conformers, those with predicted diffusion cross-sections consistent with the ion mobility experiment were further selected and their IR spectra simulated using a hybrid quantum mechanical/semiempirical method at the ONIOM DFT/B3LYP/6-31 g(d)/AM1 level. In ECD mass spectrometry, the c/z product ion abundance (PIA) has been analyzed for the two charge states and revealed drastic differences. For the doubly protonated species, N – C α bond cleavage occurs only on the N and C terminal parts, while a periodic distribution of PIA is clearly observed for the triply charged peptides. These PIA distributions have been rationalized by comparison with the inverse of the distances from the protonated sites to the carbonyl oxygens for the conformations suggested from IR and IM experiments. Structural assignment for the amyloid peptide is then made possible by the combination of these three experimental techniques that provide complementary information on the possible secondary structure adopted by peptides. Although globular conformations are favored for the doubly protonated peptide, incrementing the charge state leads to a conformational transition towards extended structures with 3 10- and α-helix motifs. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Purpose: Our goals were to carry out an anatomical description of the internal architecture of the supinator muscle in order to describe potentially compressive structures for the deep branch of the radial nerve (DBRN) and to establish reference landmarks for the surgical treatment of radial tunnel syndrome. Methods: Thirty upper limbs were dissected. The pennation angle of proximal and distal arcades of the supinator to the radial shaft axis was measured. Possible compressive structures of both superficial and deep heads of supinator were recorded. Proximal and distal arcades of the superficial layer of the supinator were classified according to their fiber content as tendinous, musculo-tendinous, muscular or membranous. The distances of superficial layer of the supinator muscle to the humeroradial joint line and lateral epicondyle were measured. Results: Pennation angle was 33.6° (±4.2°) for the superficial layer and 50.2° (±6.6°) for the deep layer. The difference was statistically significant ( p < 0.0001). The proximal arcade was purely tendinous in 20 cases (66.7 %). The distal arcade was mainly tendinous or musculo-tendinous (70 %). The average distance between the lateral epicondyle and the proximal arcade was 41.6 mm. We did not find any other potentially compressive structure within DBRN course between both layers. Conclusion: Our anatomical results about pennation angle could be used as a basis for a thorough functional study about the supinator. Both proximal and distal arcades appeared as the two zones ables to compress the DBRN. Their localization should help the surgeon for the DBRN neurolysis. [ABSTRACT FROM AUTHOR]

There is an increasing interest in exploring how the mechanisms that regulate gene expression might generate diversity in phenotypes as a function of habitat utilisation (at both inter- and intra-specific levels). Prolactin (PRL) is the main hormone involved in adaptation to low salinity in teleosts. Several mechanisms regulating PRL-A gene expression have been described. The main mechanisms involve Pit-1 binding sites and length polymorphism of a short sequence repeat (SSR) located in the proximal promoter (PP) of the gene. Together, these processes may generate phenotypes with potentially distinct physiological responses to salinity. To gain insight into their relative roles and importance, we sequenced the PP of the PRL-A gene in the euryhaline European sea bass ( Dicentrarchus labrax) and in the stenohaline sister species, Dicentrarchus punctatus. Then, we assessed the presence of both SSR and binding elements in PP among several teleost lineages, by checking available data from the literature and GenBank. The sequence of PRL-A PP was completely distinct between the percomorphs and other lineages such as salmoniform, siluriform and cypriniform, except for short stretches of nucleotides that were highly conserved across all species, also including mammals. Most of them were identified as putative cis-regulatory elements, including Pit-1, but also δEF1, c-ETS, CEBP, and GATA binding factor 2, previously unreported as regulating PRL-A transcription in teleosts, but involved in gene regulation in mammals. This result suggests that there is greater conservation of PRL-A regulatory mechanisms across vertebrate lineages than previously thought, and offers new perspectives for future studies. The presence and homology of an SSR in the PP of PRL-A gene of percomorphs was demonstrated, but no SSR polymorphisms were found amongst the two Dicentrarchus species, or within natural D. labrax populations covering the known range of natural genetic variation, including marine, brackish water and freshwater populations. [ABSTRACT FROM AUTHOR]

Ices are omnipresent in cold regions in space on, e.g., comets, dust grains, transneptunian objects, surfaces of planets and their satellites. The dominant molecule in such ices is water, but also other small molecules or even complex organic molecules (COMs) may be present. Ionizing radiation (UV photons, electrons, ions from cosmic rays or solar wind) induces several physico-chemical processes such as radiolysis. The fragmentation of initial molecules followed by chemical reactions between radicals may lead to formation of new molecules. Furthermore, also implanted projectiles can contribute to chemistry by forming new molecular species. Other observed effects include structural changes (compaction, amorphization) and desorption (sputtering) of particles from the surface. At CIMAP (Caen, France), using the different beam lines of the GANIL facility, and at GSI (Darmstadt, Germany), the interaction of swift highly charged heavy ions with astrophysical ices has been studied in a wide projectile energy range from keV to GeV. Here, two examples of our studies on astrophysical and astrochemical applications will be discussed in detail: 1) the synthesis of COMs under irradiation of ices made of small molecules, and 2) radiosensitivity of COMs such as pyridine, glycine and adenine, both for isolated molecules in the gas phase and in condensed phase. Special emphasis is given on pyridine and pyridine in water matrix. [ABSTRACT FROM AUTHOR]

Spawning and nursery habitats are often spatially disjunct as a consequence of specific life history stage habitat requirements and spatiotemporal habitat changes. Nevertheless, free‐swimming larvae originating from spawning habitats must reach productive nurseries to maximize survival. We examined spawning and nursery habitats of northern pike (Esox lucius) over the past 50 yr to investigate how habitat connectivity and hydrological variability interact to alter the distribution of effective spawning habitat. Habitat models coupled to a least‐cost approach were developed to quantify connectivity between habitats in two contrasting regions of the St. Lawrence River (Canada): a riverine corridor lake (~ 46 km) and a large fluvial lake (~ 48 km). Our simulations demonstrate that depending on hydrological conditions, between 3% to 51% of spawning habitat used by adults in the riverine corridor, and 22% to 90% in the lake, allowed larval survival up to the fifth week of development. Although rapid dewatering of spawning habitat is responsible for most spawning losses in the fluvial lake, increasing water currents were responsible for dispersing larvae away from suitable habitats in the riverine corridor. However, stable hydrological conditions led to spatial overlapping of spawning and nursery habitats favoring larval survival and growth. In addition, downstream larval dispersal by low water currents allowed larvae to reach spatially disjunct nursery habitat, especially in the lake. Our results indicate that despite the vast areas of potentially suitable habitats provided by large vegetated floodplains of fluvial lakes, the effective spawning habitats favoring early‐life recruitment are much more heterogeneous and variable both spatially and temporally. [ABSTRACT FROM AUTHOR]

The study aims at determining which spawning sites are contributing to yellow perch ( Perca flavescens) juveniles' recruitment in Lake Saint-Pierre (St. Lawrence River, Canada). We expect to highlight new management perspectives. Thus, we investigated both natal origin and connectivity processes for young of the year prior to their first winter. Otolith chemical composition was measured at larval and juvenile stages using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Five spawning sites were sampled and discriminated using a three-elemental model (manganese, barium, strontium). Results showed that ( i) all within-lake sites contributed similarly to juvenile production and ( ii) production results from both local recruitment and lake-wide connectivity processes. The study suggests fish management should include an overall evaluation of the lake-wide recruitment. Both local and widespread actions are required, depending on the level of connectivity in the lake, which plays a central role in shaping the spatial pattern of recruitment. Finally, otolith microchemistry proves to be an efficient tool for freshwater fish managers to evaluate both natal origin and connectivity in heterogeneous aquatic ecosystems. [ABSTRACT FROM AUTHOR]

The North-east American Rainbow smelt (Osmerus mordax) is composed of two glacial races first identified through the spatial distribution of two distinct mtDNA lineages. Contemporary breeding populations of smelt in the St. Lawrence estuary comprise contrasting mixtures of both lineages, suggesting that the two races came into secondary contact in this estuary. The overall objective of this study was to assess the role of intraspecific genetic admixture in the morphological diversification of the estuarine rainbow smelt population complex. The morphology of mixed-ancestry populations varied as a function of the relative contribution of the two races to estuarine populations, supporting the hypothesis of genetic admixture. Populations comprising both ancestral mtDNA races did not exhibit intermediate morphologies relative to pure populations but rather exhibited many traits that exceeded the parental trait values, consistent with the hypothesis of transgressive segregation. Evidence for genetic admixture at the level of the nuclear gene pool, however, provided only partial support for this hypothesis. Variation at nuclear AFLP markers revealed clear evidence of the two corresponding mtDNA glacial races. The admixture of the two races at the nuclear level is only pronounced in mixed-ancestry populations dominated by one of the mtDNA lineages, the same populations showing the greatest degree of morphological diversification and population structure. In contrast, mixed-ancestry populations dominated by the alternate mtDNA lineage showed little evidence of introgression of the nuclear genome, little morphological diversification and little contemporary population genetic structure. These results only partially support the hypothesis of transgressive segregation and may be the result of the differential effects of natural selection acting on admixed genomes from different sources. [ABSTRACT FROM AUTHOR]

It is common practice in many centers to offer antithrombotic medications to women with unexplained recurrent miscarriage, in the presence or absence of inherited thrombophilia. Although no benefit of aspirin vs placebo has been clearly demonstrated, a double-blind placebo-controlled trial on the effect of low-molecular-weight heparin is lacking. We enrolled 258 pregnant women with a history of unexplained recurrent miscarriage (⩾2 consecutive miscarriages before 15 weeks' gestation) and a negative thrombophilia workup. They were randomly assigned to receive one daily subcutaneous injection of enoxaparin 40 mg or placebo until 35 weeks' gestation. We included 256 women (mean age 32 years, ⩾3 miscarriages: 72%; mean gestational age 39 days of amenorrhea) in the intention-to-treat analysis; 66.6% of 138 who received enoxaparin had a live birth vs 72.9% of 118 who received placebo. The absolute difference was -6% (95% CI, -17.1 to 5.1), excluding a 10% increase in the rate of live-birth on enoxaparin (P = .34). In this first randomized, double-blind, placebo-controlled trial, enoxaparin (40 mg once daily) did not improve the chance of a live birth in nonthrombophilic women with unexplained recurrent miscarriage. This trial is registered at www.ClinicalTrials.gov as #NCT00740545 and the French National Health and Drug Safety Agency (EudraCT #2006-003350-18). [ABSTRACT FROM AUTHOR]

• Use of SFC in routine analysis for the QC of medicines and food supplements. • "Dilute-and-shoot" approach as preparation technique for complex samples in SFC. • Matrix effect was monitored and compared between different types of oily matrices. • Implementation of a control strategy based on a three-level SST. • Differences in manufacturing and QC suggested between medicines and food supplements. Vitamin D 3 is a key micronutrient whose intakes are inadequate for most populations worldwide. Supplementation with medicines or food supplements is commonly prescribed to correct this imbalance and the quality of these products must be ensured. In this context, a generic methodology for the assay of vitamin D 3 in oily formulations is proposed using supercritical fluid chromatography coupled to mass spectrometry (SFC-MS). It is in line with green analytical chemistry principles and combines the use of i) a fast and robust analytical method (4.0 min analysis time) ii) an easy sample preparation compatible with high throughput analysis ("dilute-and-shoot" approach) and iii) a relevant control strategy. Seventeen products from multiple manufacturers and encompassing a large content range were evaluated in this study. They were classified in four groups to streamline their processing considering the use of a matrix-matched calibration procedure. Matrix effect was thoroughly studied and was found to be low (99–106%), stable intra/inter-series and comparable between the different groups and types of matrices. The implemented control strategy was based on a three-level system suitability tests (SST). Level 1 SST: resolution of the critical pair that was above 1.5 for all analysis series. Level 2 SST: evaluation of the adequacy of the calibration for a QC sample in terms of recovery that was between 97% and 104% with a variability between 1% and 2%. Level 3 SST: method trueness that was between 95% and 102%. Sample analysis highlighted differences in types of products and dosage forms. This is the first study to propose a complete strategy for the quality control of vitamin D 3 oily formulations and should prove useful in QC laboratories. [ABSTRACT FROM AUTHOR]

Metapopulation dynamics over the course of an invasion are usually difficult to grasp because they require large and reliable data collection, often unavailable. The invasion of the fish-free freshwater ecosystems of the remote sub-Antarctic Kerguelen Islands following man-made introductions of brown trout (Salmo trutta) in the 1950's is an exception to this rule. Benefiting from a full long term environmental research monitoring of the invasion, we built a Bayesian dynamic metapopulation model to analyze the invasion dynamics of 85 river systems over 51 years. The model accounted for patch size (river length and connections to lakes), alternative dispersal pathways between rivers, temporal trends in dynamics, and uncertainty in colonization date. The results show that the model correctly represents the observed pattern of invasion, especially if we assume a coastal dispersal pathway between patches. Landscape attributes such as patch size influenced the colonization function, but had no effect on propagule pressure. Independently from patch size and distance between patches, propagule pressure and colonization function were not constant through time. Propagule pressure increased over the course of colonization, whereas the colonization function decreased, conditional on propagule pressure. The resulting pattern of this antagonistic interplay is an initial rapid invasion phase followed by a strong decrease in the invasion rate. These temporal trends may be due to either adaptive processes or environmental gradients encountered along the colonization front. It was not possible to distinguish these two hypotheses. Because invasibility of Kerguelen Is. freshwater ecosystems is very high due to the lack of a pre-existing fish fauna and minimal human interference, our estimates of invasion dynamics represent a blueprint for the potential of brown trout invasiveness in pristine environments. Our conclusions shed light on the future of polar regions where, because of climate change, fish-free ecosystems become increasingly accessible to invasion by fish species. [ABSTRACT FROM AUTHOR]

Abstract: This paper focuses on implementing a design space approach and on the critical process parameters (CPPs) to consider when applying the Quality by Design (QbD) concepts outlined in ICH Q8(R2), Q9 and Q10 to analytical method development and optimization for three chiral compounds developed as modulators of small conductance calcium-activated potassium (SK) channels. In this sense, an HPLC method using a polysaccharide-based stationary phase containing a cellulose tris (4-chloro-3-methylphenylcarbamate) chiral selector in polar organic solvent chromatography mode was considered. The effects of trifluoroacetic acid (TFA) and n-hexane concentration in an acetonitrile (MeCN) mobile phase were investigated under a wide range of column temperatures. Good correlations were found between the observed data obtained after using a central composite design and the expected chromatographic behaviours predicted by applying the design of experiments-design space (DoE-DS) methodology. The critical quality attribute represented here by the separation criterion (S crit) allowed assessing the quality of the enantioseparation. Baseline separation for the compounds of interest in an analysis time of less than 20min was possible due to the original and powerful tools applied which facilitated an enhanced method comprehension. Finally, the advantage of the DoE-DS approach resides in granting the possibility to concurrently assess robustness and identify the optimal conditions which are compound dependent. [Copyright &y& Elsevier]

Abstract: The microscopic structures of neat liquid nicotine and nicotine–water mixtures are examined through infrared spectroscopy and laser resonant desorption mass-spectroscopy. The infrared spectra of the solutions are analyzed using DFT calculations of homogenous and mixed hydrogen-bonded clusters. Neat nicotine and hydrated nicotine cluster are experimentally observed through IR laser resonant desorption of a nicotine/water ice mixture followed by laser ionization mass-spectrometry. A sizable fraction of those cluster ions is the result of laser ionization of small neutral clusters already present in the sample. [Copyright &y& Elsevier]

The bonga shad, Ethmalosa fimbriata, is a West African pelagic species still abundant in most habitats of its distribution range and thought to be only recently affected by anthropogenic pressure (habitat destruction or fishing pressure). Its presence in a wide range of coastal habitats characterised by different hydrodynamic processes, represents a case study useful for evaluating the importance of physical structure of the west African shoreline on the genetic structure of a small pelagic species. To investigate this question, the genetic diversity of E. fimbriata was assessed at both regional and species range scales, using mitochondrial (mt) and nuclear DNA markers. Whereas only three panmictic units were identified with mtDNA at the large spatial scale, nuclear genetic markers (EPIC: exon-primed intron-crossing) indicated a more complex genetic pattern at the regional scale. In the northern-most section of shad’s distribution range, up to 4 distinct units were identified. Bayesian inference as well as spatial autocorrelation methods provided evidence that gene flow is impeded by the presence of deep-water areas near the coastline (restricting the width of the coastal shelf), such as the Cap Timiris and the Kayar canyons in Mauritania and Senegal, respectively. The added discriminatory power provided by the use of EPIC markers proved to be essential to detect the influence of more subtle, contemporary processes (e.g. gene flow, barriers, etc.) acting within the glacial refuges identified previously by mtDNA. [ABSTRACT FROM AUTHOR]