Characterization of Monomeric Intermediates during VSV Glycoprotein Structural Transition

Entry of enveloped viruses requires fusion of viral and cellular membranes, driven by conformational changes of viral glycoproteins. Crystal structures provide static pictures of pre- and post-fusion conformations of these proteins but the transition pathway remains elusive. Here, using several biophysical techniques, including analytical ultracentrifugation, circular dichroïsm, electron microscopy and small angle X-ray scattering, we have characterized the low-pH-induced fusogenic structural transition of a soluble form of vesicular stomatitis virus (VSV) glycoprotein G ectodomain (Gth, aa residues 1–422, the fragment that was previously crystallized). While the post-fusion trimer is the major species detected at low pH, the pre-fusion trimer is not detected in solution. Rather, at high pH, Gth is a flexible monomer that explores a large conformational space. The monomeric population exhibits a marked pH-dependence and adopts more elongated conformations when pH decreases. Furthermore, large relative movements of domains are detected in absence of significant secondary structure modification. Solution studies are complemented by electron micrographs of negatively stained viral particles in which monomeric ectodomains of G are observed at the viral surface at both pH 7.5 and pH 6.7. We propose that the monomers are intermediates during the conformational change and thus that VSV G trimers dissociate at the viral surface during the structural transition

The generality of changes in the trait composition of fish and invertebrate communities after flow restoration in a large river (French Rhône)

1. A multiple-trait-based approach can provide predictions and interpretations of the responses of freshwater communities to river restoration that apply in different taxonomic contexts. We compared the observed and predicted effects of restoration on sets of traits in fish and invertebrate communities in four reaches of the Rhône River. Restoration included minimum flow increases in three bypassed main channels and the reconnection of eight floodplain channels. 2. Predictions (described in detail in three other articles in this Special Issue) were based on habitat models that related the density of modelled taxa to their physical habitats. We used trait information extracted from the literature to translate predicted taxonomic changes into predicted changes in traits. Observed changes in traits calculated for modelled taxa and for all taxa in the community were both compared to predictions. 3. In 10 of 12 cases, observed changes in traits correlated with predicted ones. With few exceptions, the agreement was higher for fish and invertebrates in the main channels than for invertebrates in floodplain channels. Predictions translated to the trait category level improved those at the taxonomic level in 5/6 and 4/6 cases for modelled taxa and all taxa, respectively. However, the improvement was statistically significant according to a null model for 1/6 and 3/6 cases for modelled taxa and all taxa, respectively. 4. The validation of trait predictions suggested that traits related to locomotion and attachment, as well as general biology and physiology, were particularly suited to predicting and understanding the effects of physical restoration. For example, after restoration, clingers and passive filter feeders dominated invertebrate communities in the main channels, whereas invertebrate communities in the floodplain underwent a selection of traits frequent in running water (clingers, flattened shape and gill respiration). Within fish communities, the periodic life-history strategy that characterises fish species in downstream reaches (long life span, large body, late sexual maturity) increased with restoration, whereas the opportunistic strategy decreased. 5. Our results suggest that a better understanding of how hydraulics shapes traits in riverine systems is critically needed for assessing the effects of restoration measures impacting flow. In addition, existing trait databases (especially for fish) should be expanded to better reflect the energetic trade-offs that organisms must make in various flow contexts

Riparian and microhabitat factors determine the structure of the EPT community in Andean headwater rivers of Ecuador

"This is the peer reviewed version of the following article: Vimos-Lojano, D.J., F. Martínez-Capel, and H. Hampel. 2017. Riparian and Microhabitat Factors Determine the Structure of the EPT Community in Andean Headwater Rivers of Ecuador. Ecohydrology 10 (8). Wiley: e1894. doi:10.1002/eco.1894, which has been published in final form at https://doi.org/10.1002/eco.1894. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."[EN] This research was conducted in the high-Andean basin of the Zhurucay River in southern Ecuador. In 4 river reaches, 19 sampling campaigns were conducted per reach spread over a period of 35months. The biotic samples were selected in the periods with greatest flow stability. Parallel to each sampling, 37 environmental variables grouped into 3 factors (riparian corridor, hydromorphology, and water quality) were recorded. The study aimed to analyse during periods of stable flow the influence of these environmental factors on the structure and density of the EPT community (Ephemeroptera, Plecoptera, Trichoptera) in a quasi-pristine aquatic ecosystem. Multivariate statistical analysis revealed that the Froude number, gravel type, and width/depth ratio are the most relevant hydromorphological variables explaining variations in EPT density. Xiphocentronidae, Contulma, and Helicopsyche were observed to have a relationship with the order of the river, while Ochrotrichia, Nectopsyche, and Phylloicus varied with the type of riparian vegetation. Phylloicus, Ochrotrichia, and Nectopsyche were common in lentic sites, while the proportion of gravel and the width/depth ratio restricted the genus Helicopsyche. The only relevant water quality factor was the total phosphorus, which was related with 2 taxa. In conclusion, although macroinvertebrates are currently employed in water quality studies, riparian vegetation and hydromorphological factors are determinant for their communities in pristine Andean rivers. Such factors are therefore crucial in the study of environmental flows and the assessment of the ecological integrity.This research was funded by the SENESCYTPIC 11-726 Project (Interpretation of hydro-ecological processes as a basis for assessing the ecological flow in the Paute and Jubones watershed), the hydroelectric company CELECEP, and DIUC (Investigation Department of the University of Cuenca). Thanks are due to the SENESCYT project PIC 11-715 (Impact of land use change in the hydrogeochemistry of Andean basins) for providing the hydrological data used in this study. Further, financial support was provided by SENESCYT through a fellowship granted to the first author for carrying out his doctoral programme and through the PROMETEO fellowship awarded to the third author. We are greateful to Ing. Andres Quichimbo for reviewing the hydrological data, and the staff of the Aquatic Ecology Laboratory at the University of Cuenca for their assistance and field logistics. Finally, the authors are grateful to Prof. Jan Feyen for constructive polishing edition the manuscript.Vimos-Lojano, D.; Martinez-Capel, F.; Hampel, H. (2017). Riparian and microhabitat factors determine the structure of the EPT community in Andean headwater rivers of Ecuador. Ecohydrology. 10(8):1-15. https://doi.org/10.1002/eco.1894S115108Albariño, R. J., & Balseiro, E. G. (2002). Leaf litter breakdown in Patagonian streams: native versus exotic trees and the effect of invertebrate size. Aquatic Conservation: Marine and Freshwater Ecosystems, 12(2), 181-192. doi:10.1002/aqc.511ALLAN, D., ERICKSON, D., & FAY, J. (1997). The influence of catchment land use on stream integrity across multiple spatial scales. Freshwater Biology, 37(1), 149-161. doi:10.1046/j.1365-2427.1997.d01-546.xAllan, J. D. (2004). Landscapes and Riverscapes: The Influence of Land Use on Stream Ecosystems. Annual Review of Ecology, Evolution, and Systematics, 35(1), 257-284. doi:10.1146/annurev.ecolsys.35.120202.110122Allen, D. C., & Vaughn, C. C. (2010). Complex hydraulic and substrate variables limit freshwater mussel species richness and abundance. Journal of the North American Benthological Society, 29(2), 383-394. doi:10.1899/09-024.1Almeida, D., Merino-Aguirre, R., & Angeler, D. G. (2013). Benthic invertebrate communities in regulated Mediterranean streams and least-impacted tributaries. Limnologica, 43(1), 34-42. doi:10.1016/j.limno.2012.02.003BASTIAN, M., PEARSON, R. G., & BOYERO, L. (2008). Effects of diversity loss on ecosystem function across trophic levels and ecosystems: A test in a detritus-based tropical food web. Austral Ecology, 33(3), 301-306. doi:10.1111/j.1442-9993.2007.01817.xBeisel, J.-N., Usseglio-Polatera, P., & Moreteau, J.-C. (2000). 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Which variables should be used to link invertebrate drift to river hydraulic conditions? Fundamental and Applied Limnology / Archiv für Hydrobiologie, 187(3), 191-205. doi:10.1127/fal/2015/0745Graça, M. A. S. (2001). The Role of Invertebrates on Leaf Litter Decomposition in Streams - a Review. International Review of Hydrobiology, 86(4-5), 383-393. doi:10.1002/1522-2632(200107)86:4/53.0.co;2-dHaggerty, S. M., Batzer, D. P., & Jackson, C. R. (2002). Hydrobiologia, 479(1/3), 143-154. doi:10.1023/a:1021034106832Hampel, H., Cocha, J., & Vimos, D. (2010). Incorporation of aquatic ecology to the hydrological investigation of ecosystems in the high Andes. MASKANA, 1(1), 91-100. doi:10.18537/mskn.01.01.07Hannah, D. M., Brown, L. E., Milner, A. M., Gurnell, A. M., McGregor, G. R., Petts, G. E., … Snook, D. L. (2007). Integrating climate–hydrology–ecology for alpine river systems. Aquatic Conservation: Marine and Freshwater Ecosystems, 17(6), 636-656. doi:10.1002/aqc.800Holomuzki, J. R., Feminella, J. W., & Power, M. E. (2010). Biotic interactions in freshwater benthic habitats. Journal of the North American Benthological Society, 29(1), 220-244. doi:10.1899/08-044.1Holzenthal, R. W., & Ríos-Touma, B. (2012). Contulma paluguillensis(Trichoptera:Anomalopsychidae), a new caddisfly from the high Andes of Ecuador, and its natural history. Freshwater Science, 31(2), 442-450. doi:10.1899/11-067.1Jacobsen, D. (2003). Altitudinal changes in diversity of macroinvertebrates from small streams in the Ecuadorian Andes. Archiv für Hydrobiologie, 158(2), 145-167. doi:10.1127/0003-9136/2003/0158-0145Jacobsen, D. (2004). Contrasting patterns in local and zonal family richness of stream invertebrates along an Andean altitudinal gradient. Freshwater Biology, 49(10), 1293-1305. doi:10.1111/j.1365-2427.2004.01274.xJacobsen, D., Andino, P., Calvez, R., Cauvy-Fraunié, S., Espinosa, R., & Dangles, O. (2014). Temporal variability in discharge and benthic macroinvertebrate assemblages in a tropical glacier-fed stream. Freshwater Science, 33(1), 32-45. doi:10.1086/674745Jacobsen, D., Cauvy-Fraunie, S., Andino, P., Espinosa, R., Cueva, D., & Dangles, O. (2014). Runoff and the longitudinal distribution of macroinvertebrates in a glacier-fed stream: implications for the effects of global warming. Freshwater Biology, 59(10), 2038-2050. doi:10.1111/fwb.12405Jacobsen, D., & Encalada, A. (1998). The macroinvertebrate fauna of Ecuadorian highland streams in the wet and dry season. Fundamental and Applied Limnology, 142(1), 53-70. doi:10.1127/archiv-hydrobiol/142/1998/53Jacobsen, D., & Marín, R. (2007). Bolivian Altiplano streams with low richness of macroinvertebrates and large diel fluctuations in temperature and dissolved oxygen. Aquatic Ecology, 42(4), 643-656. doi:10.1007/s10452-007-9127-xJacobsen, D., Rostgaard, S., & Vásconez, J. J. (2003). Are macroinvertebrates in high altitude streams affected by oxygen deficiency? Freshwater Biology, 48(11), 2025-2032. doi:10.1046/j.1365-2427.2003.01140.xJACOBSEN, D., SCHULTZ, R., & ENCALADA, A. (1997). Structure and diversity of stream invertebrate assemblages: the influence of temperature with altitude and latitude. Freshwater Biology, 38(2), 247-261. doi:10.1046/j.1365-2427.1997.00210.xJowett, I. G. (1993). A method for objectively identifying pool, run, and riffle habitats from physical measurements. New Zealand Journal of Marine and Freshwater Research, 27(2), 241-248. doi:10.1080/00288330.1993.9516563LADLE, M., COOLING, D. A., WELTON, J. S., & BASS, J. A. B. (1985). Studies on Chironomidae in experimental recirculating stream systems. II. The growth, development and production of a spring generation of Orthocladius (Euorthodadius) calvus Pinder. Freshwater Biology, 15(2), 243-255. doi:10.1111/j.1365-2427.1985.tb00197.xLamouroux, N., Dolédec, S., & Gayraud, S. (2004). Biological traits of stream macroinvertebrate communities: effects of microhabitat, reach, and basin filters. Journal of the North American Benthological Society, 23(3), 449-466. doi:10.1899/0887-3593(2004)0232.0.co;2Lancaster, J., & Belyea, L. R. (1997). Nested Hierarchies and Scale-Dependence of Mechanisms of Flow Refugium Use. Journal of the North American Benthological Society, 16(1), 221-238. doi:10.2307/1468253LI, A. O. Y., & DUDGEON, D. (2008). Food resources of shredders and other benthic macroinvertebrates in relation to shading conditions in tropical Hong Kong streams. Freshwater Biology, 53(10), 2011-2025. doi:10.1111/j.1365-2427.2008.02022.xLópez-López, E., & Sedeño-Díaz, J. E. (2014). Biological Indicators of Water Quality: The Role of Fish and Macroinvertebrates as Indicators of Water Quality. Environmental Indicators, 643-661. doi:10.1007/978-94-017-9499-2_37Matson, E., & Bart, D. (2013). Interactions among fire legacies, grazing and topography predict shrub encroachment in post-agricultural páramo. Landscape Ecology, 28(9), 1829-1840. doi:10.1007/s10980-013-9926-5McIntosh, M. D., Benbow, M. E., & Burky, A. J. (2002). Effects of stream diversion on riffle macroinvertebrate communities in a Maui, Hawaii, stream. River Research and Applications, 18(6), 569-581. doi:10.1002/rra.694MÉRIGOUX, S., LAMOUROUX, N., OLIVIER, J.-M., & DOLÉDEC, S. (2009). Invertebrate hydraulic preferences and predicted impacts of changes in discharge in a large river. Freshwater Biology, 54(6), 1343-1356. doi:10.1111/j.1365-2427.2008.02160.xMesa, L. M. (2010). Effect of spates and land use on macroinvertebrate community in Neotropical Andean streams. Hydrobiologia, 641(1), 85-95. doi:10.1007/s10750-009-0059-4Meyer , J. Wallace , J. Press , M. Huntly , N. Levin , S 2001 Lost linkages and lotic ecology: Rediscovering small streamsMeyer, J. L., Strayer, D. L., Wallace, J. B., Eggert, S. L., Helfman, G. S., & Leonard, N. E. (2007). The Contribution of Headwater Streams to Biodiversity in River Networks1. JAWRA Journal of the American Water Resources Association, 43(1), 86-103. doi:10.1111/j.1752-1688.2007.00008.xMiserendino, M. L., Casaux, R., Archangelsky, M., Di Prinzio, C. Y., Brand, C., & Kutschker, A. M. (2011). Assessing land-use effects on water quality, in-stream habitat, riparian ecosystems and biodiversity in Patagonian northwest streams. Science of The Total Environment, 409(3), 612-624. doi:10.1016/j.scitotenv.2010.10.034Miserendino, M. L., & Masi, C. I. (2010). The effects of land use on environmental features and functional organization of macroinvertebrate communities in Patagonian low order streams. Ecological Indicators, 10(2), 311-319. doi:10.1016/j.ecolind.2009.06.008Miserendino, M. L., & Pizzolán, L. A. (2001). Abundance and Altitudinal Distribution of Ephemeroptera in an Andean-Patagonean River System (Argentina). 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Journal of the North American Benthological Society, 16(2), 391-409. doi:10.2307/1468026Principe, R. E., Raffaini, G. B., Gualdoni, C. M., Oberto, A. M., & Corigliano, M. C. (2007). Do hydraulic units define macroinvertebrate assemblages in mountain streams of central Argentina? Limnologica, 37(4), 323-336. doi:10.1016/j.limno.2007.06.001Quinn, G. P., & Keough, M. J. (2002). Experimental Design and Data Analysis for Biologists. doi:10.1017/cbo9780511806384Rempel, L. L., Richardson, J. S., & Healey, M. C. (2000). Macroinvertebrate community structure along gradients of hydraulic and sedimentary conditions in a large gravel-bed river. Freshwater Biology, 45(1), 57-73. doi:10.1046/j.1365-2427.2000.00617.xRice, S. P., Buffin-Bélanger, T., Lancaster, J., & Reid, I. (2007). 24 Movements of a macroinvertebrate (Potamophylax latipennis) across a gravel-bed substrate: effects of local hydraulics and micro-topography under increasing discharge. Developments in Earth Surface Processes, 637-659. doi:10.1016/s0928-2025(07)11152-4Rice, S. P., Greenwood, M. T., & Joyce, C. B. (2001). Tributaries, sediment sources, and the longitudinal organisation of macroinvertebrate fauna along river systems. Canadian Journal of Fisheries and Aquatic Sciences, 58(4), 824-840. doi:10.1139/f01-022Ríos-Touma, B., Encalada, A. C., & Prat Fornells, N. (2011). Macroinvertebrate Assemblages of an Andean High-Altitude Tropical Stream: The Importance of Season and Flow. International Review of Hydrobiology, 96(6), 667-685. doi:10.1002/iroh.201111342Ríos-Touma, B., Holzenthal, R. W., Huisman, J., Thomson, R., & Rázuri-Gonzales, E. (2017). Diversity and distribution of the Caddisflies (Insecta: Trichoptera) of Ecuador. PeerJ, 5, e2851. doi:10.7717/peerj.2851Rolls, R. J., Leigh, C., & Sheldon, F. (2012). Mechanistic effects of low-flow hydrology on riverine ecosystems: ecological principles and consequences of alteration. 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Fatores influenciando a estrutura e distribuição espacial dos peixes nos Igarapés de cabeceira do Parque Nacional do Jaú, Amazônia Central

The aim of this study was to investigate the influence of spatial variation in river channels and habitats on the distribution of fish communities in the headwater streams of the Jaú River System, a blackwater tributary of the Negro River. Collections and measurements were made in 34 headwater streams during the period of November-December, 1998. Fish were captured with fish traps and hand nets along standard reaches of two meanders. Data on benthic habitat structure, stream depth and width were collected along lateral transects in each sample reach. A total of 66 fish species from 24 families were collected and classified into seven trophic guilds: allocthonous insectivore, autochthonous insectivore, general insectivore, piscivore, detritivorous planktivore, detritivorous insectivore and insectivorous piscivore. Variations in the distribution and diversity of bottom substrates were important factors influencing fish community structures in these systems. Also, variation in stream size explained the observed variability in fish communities. © 2014, Instituto Internacional de Ecologia. All right reserved

Ensembles de particules à pénétrabilité limitée. Application à l'étude des champs de forces superficiels et interfaciaux

Définition des ensembles : particules s'attirant si la distance r des centres est> r0; se repoussant dans le cas contraire. On admet que r a une limite inférieure moyenne r1. La pression interne de ces ensembles se calcule directement en fonction de r1. Elle peut devenir négative si la pénétrabilité des particules augmente. Une variation de densité engendre un champ de force : le travail de cohésion et l'énergie superficielle de ces ensembles se calculent en fonction de r1 et peuvent changer de signe si r1 diminue. Le champ de force superficiel et interfacial est spécialement étudié en fonction de r1 et l'augmentation de la pénétrabilité des particules peut provoquer son renversement. La tendance à migration des particules peut s'en trouver modifiée (anamigmatisme)

Introduction à la chimie physique minérale par K. K. Harvey et G. B. Porter, 1967

Mérigoux Henri. Introduction à la chimie physique minérale par K. K. Harvey et G. B. Porter, 1967. In: Bulletin de la Société française de Minéralogie et de Cristallographie, volume 90, 4, 1967. Réunion annuelle de l'Association Française de Cristallographie, Lyon, 13-15 avril 1967