Role of stream morphology and predators as driving factors for the abundance of two common ephemeropteran genera in rural hilly areas

Lotic environments may play an important role for semi-aquatic species. Streams are among the most threatened breeding habitats for some macrobenthos taxa. Ephemeropterans are often considered good bioindicators. Two of the most common genera of mayflies are Ecdyonurus and Baetis. The species from the first genus are very sensitive toward organic pollution, while the second genus might be quite resistant. The aim of this study was to evaluate the relative importance of stream morphological features on the abundance of Ecdyonurus and Baetis genera at unpolluted sites upstream an urbanised area. Further, I assessed the relationships between the abundance of the studied mayflies and the common spring and stream predators, i.e. salamander larvae and fish. The substrate complexity, reflecting shelter availability, was the main feature affecting the abundance of both genera. The two genera showed distinct requirements only in terms of stream shading, with Baetis preferring sunny sites and Ecdyonurus shady sites. Baetis showed higher affinity for streams with trout occurrence and Ecdyonurus for streams with Salamandra salamandra larvae occurrence. This study underlines that when pollution is not a main factor, both sensitive and insensitive common Ephemeroptera genera show similar habitat requirements and that watercourse substrate heterogeneity should be attentively preserved

Cave Communities: From the Surface Border to the Deep Darkness

The discipline of subterranean biology has provided us incredible information on the diversity, ecology and evolution of species living in different typologies of subterranean habitats. However, a general lack of information on the relationships between cave species still exists, leaving uncertainty regarding the dynamics that hold together cave communities and the roles of specific organisms (from the least to the most adapted species) for the community, as well as the entire ecosystem. This Special Issue aims to stimulate and gather studies which are focusing on cave communities belonging to all different typologies of subterranean habitats, with the overarching goal to corroborate the key role of the subterranean biology in ecological and evolutionary studies

Is landscape of fear of macroinvertebrate communities a major determinant of mesopredator and prey activity?

Macroinvertebrate foragers play an important role on the trophic structures of freshwater environments, and multiple trophic levels occur among macroinvertebrate communities providing very interesting scenarios for testing scientific hypotheses. One of the most intriguing aspect to understand is the role played by the landscape of fear (LOF) on macrobenthos density and activity. With this pilot study we wanted to test if LOF at the macrobenthos community levels plays a role in determining the density of both prey and mesopredators. During two consecutive years, we evaluated, with both day and night surveys, the density of two mesopredator triclad species and of one detritivore prey crustacean species, and we compared them to the number of respective predators occurring in the macroinvertebrate community. LOF levels at the macroinvertebrate community did not reduce the abundance of the target taxa. One of the triclad species was instead positively related to the levels of LOF assessed for it on the basis of the available knowledge. The broad implication of the research is that the abundance of freshwater macroinvertebrates is not mainly linked to the predation risk at the community level, suggesting that also for researches on macrobenthos LOF analyses should take in consideration the role of top predators

Rapid adaptation to invasive predators overwhelms natural gradients of intraspecific variation

Invasive predators can exert strong selection on native populations. If selection is strong enough, populations could lose the phenotypic variation caused by adaptation to heterogeneous environments. We compare frog tadpoles prior to and 14 years following invasion by crayfish. Prior to the invasion, populations differed in their intrinsic developmental rate, with tadpoles from cold areas reaching metamorphosis sooner than those from warm areas. Following the invasion, tadpoles from invaded populations develop faster than those from non-invaded populations. This ontogenetic shift overwhelmed the intraspecific variation between populations in a few generations, to the point where invaded populations develop at a similar rate regardless of climate. Rapid development can have costs, as fast-developing froglets have a smaller body size and poorer jumping performance, but compensatory growth counteracts some costs of development acceleration. Strong selection by invasive species can disrupt local adaptations by dampening intraspecific phenotypic variation, with complex consequences on lifetime fitness

Microhabitat analyses support relationships between niche breadth and range size when spatial autocorrelation is strong

Multiple evidence of positive relationships between nice breadth and range size (NB\u2013RS) suggested that this can be a general ecological pattern. However, correlations between niche breadth and range size can emerge as a by-product of strong spatial structure of environmental variables. This can be problematic because niche breadth is often assessed using broad-scale macroclimatic variables, which suffer heavy spatial autocorrelation. Microhabitat measurements provide accurate information on species tolerance, and show limited autocorrelation. The aim of this study was to combine macroclimate and microhabitat data to assess NB\u2013RS relationships in European plethodontid salamanders (Hydromantes), and to test whether microhabitat variables with weak autocorrelation can provide less biased NB\u2013RS estimates across species. To measure macroclimatic niche, we gathered comprehensive information on the distribution of all Hydromantes species, and combined them with broad-scale climatic layers. To measure microhabitat, we recorded salamander occurrence across > 350 caves and measured microhabitat features influencing their distribution: humidity, temperature and light. We assessed NB\u2013RS relationships through phylogenetic regression; spatial null-models were used to test whether the observed relationships are a by-product of autocorrelation. We observed positive relationships between niche breadth and range size at both the macro- and microhabitat scale. At the macroclimatic scale, strong autocorrelation heavily inflated the possibility to observe positive NB\u2013RS. Spatial autocorrelation was weaker for microhabitat variables. At the microhabitat level, the observed NB\u2013RS was not a by-product of spatial structure of variables. Our study shows that heavy autocorrelation of variables artificially increases the possibility to detect positive relationships between bioclimatic niche and range size, while fine-scale data of microhabitat provide more direct measure of conditions selected by ectotherms, and enable less biased measures of niche breadth. Combining analyses performed at multiple scales and datasets with different spatial structure provides more complete niche information and effectively tests the generality of niche breadth\u2013range size relationships

Energy-Process Integration of the Gas-Cooled/Water-Cooled Fixed-Bed Reactor Network for Methanol Synthesis

The paper deals with the techno-economical assessment of the gas-cooled/water-cooled fixed-bed reactor network for methanol synthesis. The study is the extension of the first-principles model for the watercooled reactor already proposed in our prior work (Manenti et al., 2013). Here, the optimization is extended to the steam generation and the reactor length ratio. As a result, basing on the integrated optimization of energy and process yield, we propose to significantly revise the common design. The traditional water/gas cooling reactor length ratio could be significantly reduced with consequent simultaneous increase in methanol production and steam generation as well, however preserving safety and operational ranges. The economic benefit deriving from the proposed design for a medium-scale process is estimated in more than 1.7 M€/y

Circuit quantum acoustodynamics with surface acoustic waves

The experimental investigation of quantum devices incorporating mechanical resonators has opened up new frontiers in the study of quantum mechanics at a macroscopic level$^{1,2}$. Superconducting microwave circuits have proven to be a powerful platform for the realisation of such quantum devices, both in cavity optomechanics$^{3,4}$, and circuit quantum electro-dynamics (QED)$^{5,6}$. While most experiments to date have involved localised nanomechanical resonators, it has recently been shown that propagating surface acoustic waves (SAWs) can be piezoelectrically coupled to superconducting qubits$^{7,8}$, and confined in high-quality Fabry-Perot cavities up to microwave frequencies in the quantum regime$^{9}$, indicating the possibility of realising coherent exchange of quantum information between the two systems. Here we present measurements of a device in which a superconducting qubit is embedded in, and interacts with, the acoustic field of a Fabry-Perot SAW cavity on quartz, realising a surface acoustic version of cavity quantum electrodynamics. This quantum acoustodynamics (QAD) architecture may be used to develop new quantum acoustic devices in which quantum information is stored in trapped on-chip surface acoustic wavepackets, and manipulated in ways that are impossible with purely electromagnetic signals, due to the $10^{5}$ times slower speed of travel of the mechanical waves.Comment: 12 pages, 9 figures, 1 tabl

The role of watercourse features and of landscape structure in the distribution of triclads inhabiting head waters : the example of Polycelis felina

Résumé. — Le rôle des caractères du cours d’eau et de la structure du paysage sur la distribution des triclades dans le haut des cours d’eau : l’exemple de Polycelis felina. — Le triclade Polycelis felina est un taxon intéressant par son rôle de bioindicateur important dans les cours d’eau et les petits environnements lotiques. Des informations ont été recueillies sur sa distribution dans les cours d’eau de la partie sud de la province de Lecco (N Italie) afin d’obtenir une image claire de ses préférences biologiques et écologiques et des particularités des biotopes dans lesquels on le trouve. Au total 194 sites sur 110 cours d’eau ont été prospectés durant la campagne de terrain menée en 2005 et 2006. Des populations de P. felina furent trouvées dans 26 % des sites visités. Les rôles respectifs, quant à la présence de P. felina, de la morphologie naturelle du cours d’eau, de la qualité de l’eau, et d’autres facteurs (tels la présence d’autres triclades, d’écrevisses et de larves de Salamandra salamandra) ont été analysés.Manenti Raoul. The role of watercourse features and of landscape structure in the distribution of triclads inhabiting head waters: the example of Polycelis felina. In: Revue d'Écologie (La Terre et La Vie), tome 65, n°3, 2010. pp. 279-285

DEVELOPMENT OF THE LARVAL PERIPHERAL NERVOUS SYSTEM IN THE ASCIDIAN CIONA INTESTINALIS: ROLE OF THE RETINOIC ACID AND FGF/WNT SIGNALLING PATHWAYS AND OF THE POU TRANSCRIPTION FACTORS.

The research presented in this document focuses on the development of the larval peripheral nervous system of the Tunicate Ciona intestinalis with two main aims: a) to understand how the interactions between Retinoic Acid (RA) and the FGF/WNT pathways control its development; b) to study the role played by transcription factors of the POU family in its differentiation. Within chordates, tunicates represent the sister group of vertebrates and their larvae have a typical chordate body plan. Notably, larval nervous system is formed by few cells whose organization mirrors that of vertebrates. For these reasons the species C. intestinalis, whose genome is completely sequenced, is a good animal model often used to understand the basic mechanisms of Chordate development. POU genes are an important family of transcription factors with several members that regulate the neural patterning and differentiation in both vertebrate and invertebrate embryos. C. intestinalis has only three genes coding for POU transcription factors: Ci-POU-2 Ci-POU-IV and Ci-POU-like. The gene Ci-POU-IV is specifically expressed in all peripheral nervous system (PNS) territories and in some cells of the central nervous system (CNS) during development. Since the expression of the two other genes was not previously studied in detail, a part of this research consisted in their characterization. Several experiments of in situ hybridization showed that the transcripts of Ci-POU-2 are present early during cleavage stages while Ci-POU-like gene expression is restricted to the lateral mesenchime cells of the larva and to their precursors during embryonic development. Thus the research was focused on the Ci-POU-IV gene. Its expression had been formerly studied by the research team of Prof. De Bernardi that discovered the existence of two alternative transcripts. In order to study the role that they play in neural differentiation Morpholino oligos were designed to perform gene knock-down experiments for the two different isoforms. The results from these experiments revealed that the expression of the serotonin rate-limiting synthesis enzyme, tryptophane hydroxylase (TPH), and glutamate transporter (vGlut) in the PNS neurons could be regulated by the product of the long transcript. To verify if the alternative transcripts were expressed in different PNS neuron populations in situ hybridizations were performed with a probe selective for the short isoform. These in situ hybridizations, compared to the whole expression profile of Ci-POU-IV, showed a lack of expression of the short form in the sensory epidermal neurons of the trunk. Moreover experiments were performed to understand the relationship between Ci-POU-IV and the Delta/Notch pathway. The latter has an important role in determining the cell to cell interactions in a number of taxa and to affect the neural or the epidermal fate of the PNS precursors. The Delta/Notch pathway was inhibited both using DAPT that inhibits the \uf067\u2013secretase, responsible of the correct functioning of the pathway and electroporing the pFOG::VeSu(H)DBM construct that blocks the pathway activity. Embryos treated showed an abnormal development of epidermic sensorial neurons and the following in situ hybridizations for Ci-POU-IV pointed out an ectopic expression of the gene. Furthermore the study looked for the Ci-POU-IV targets in order to identify the genes regulated by Ci-POU-IV during the PNS differentiation. A bioinformatic approach was used. The possible consensus sequences were obtained by bibliographic research of those known for the POU IV family in both invertebrates and vertebrates. These sequences have been used to build a matrix that was employed to perform a bioinformatic research in the whole C. intestinalis genome with a software elaborated by the Lemaire team of the IBDML of Marseille. The search identified 19 possible targets of Ci-POU-IV; 8 regions, corresponding to 6 genes including TPH, have been preliminary selected. The activity of the selected regions is being evaluated. The second part of the thesis has been developed during a period of research with Dr. A. Pasini at the Institut de Biologie du D\ue9veloppent of Marseille. The aim was to identify the mechanisms with which RA and the FGF/WNT pathways act on antero-posterior differentiation of PNS during C. intestinalis embryonic development. In vertebrates it was already known that during the antero-posterior extension of the body axis these pathways antagonize each other to coordinate mesoderm and nervous system differentiation. For this reason the hypothesis that an analogous mechanism could occur in other Chordates, including tunicates was tested. Thus in C. intestinalis I performed in situ hybridizations for different genes potentially involved in this mechanism. I employed also the electroporation technique with specific constructs. In particular results showed that the expression of the gene Ci-Raldh that codes for Retinaldehyde dehydrogenase, the enzyme responsible of RA synthesis, is confined to the anterior part of the tail in tailbud stage embryos. To this region is limited also the expression of some gene responsive to RA such as Ci-Hox-1 and Ci-Cyp26. On the contrary, at the posterior extremity of the tail it is predictable the existence of a source of FGF and WNT signals as shown by the expression of Ci-FGF-8 and Ci-WNT-5. Moreover, embryos treated with RA showed Ci-Hox-1 up-regulation at throughout tail epidermis and the inhibition of the posterior Ci-Hox-12 expression. On the contrary, embryos treated with FGF showed an opposite situation with Ci-Hox-12 activation and Ci-Hox-1 inhibition. Moreover, quantifications of differentiated caudal epidermal neurons and meticulous analysis of their position along the tail have been performed in late stage embryos treated with RA, FGF, their respective inhibitors and an inhibitor of the enzyme Ci-Cyp26, responsible for RA catabolism. This showed significant alterations in both the number of neurons and their position. In particular RA treatment increased the oveall number of caudal epidermal neurones but causes the loss of the most posterior ones; on the contrary FGF treatment induced a decrease in the number of neurons but maintained the posterior ones. Treatment with FGF and Ci-Cyp26 inhibitors mimicks the effects of RA while treatment with RA synthesis inhibitor mimicks the effect of FGF. On the whole a complex picture of antagonistic interactions, both direct and indirect has been revealed posing interesting questions from an evolutionary point of view