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Out of Africa : the origins of the protozoan blood parasites of the Trypanosoma cruzi clade found in bats from Africa
No full textUnderstanding geographic patterns of interaction between hosts and parasites can provide useful insight into the evolutionary history of the organisms involved. However, poor taxon sampling often hinders meaningful phylogenetic descriptions of groups of parasites. Trypanosome parasites that constitute the Trypanosoma cruzi clade are worldwide distributed infecting several mammalian species, especially bats. Diversity in this clade has been recently expanded by newly discovered species, but the common ancestor and geographical origins of this group of blood parasites are still debated. We present here results based on the molecular characterization of trypanosome isolates obtained from 1493 bats representing 74 species and sampled over 16 countries across four continents. After estimating the appropriate number of hypothetical species in our data set using GMYC models in combination with Poisson Tree Processes (mPTP) and ABGD, the 18S rRNA and gGAPDH genes were used for phylogenetic analyses to infer the major evolutionary relationships in the T. cruzi clade. Then, biogeographical processes influencing the distribution of this cosmopolitan group of parasites was inferred using BioGeoBEARS. Results revealed a large lineages diversity and the presence of trypanosomes in all sampled regions which infected 344 individuals from 31 bat species. We found eight Trypanosoma species, including: five previously known; one subspecies of Trypanosoma livingstonei (Trypanosoma cf. livingstonei); and two undescribed taxa (Trypanosoma sp. 1, Trypanosoma sp. 2), which were found exclusively in bats of the genus Miniopterus from Europe and Africa. The new taxa discovered have both an unexpected position in the global phylogeny of the T. cruzi clade. Trypanosoma sp. 1 is a sister lineage of T. livingstonei which is located at the base of the tree, whereas Trypanosoma sp. 2 is a sister lineage of the Shizotrypanum subclade that contains T. c. cruzi and T. dionisii. Ancestral areas reconstruction provided evidence that trypanosomes of the T. cruzi clade have radiated from Africa through several dispersion events across the world. We discuss the impact of these findings on the biogeography and taxonomy of this important clade of parasites and question the role played by bats, especially those from the genus Miniopterus, on the dispersal of these protozoan parasites between continents
Evolutions in estuary governance ? Reflections and lessons from Australia, France and New Caledonia
No full textEstuaries are cradles of life for the communities who live around and within them. They are valued in multiple ways for the services they provide to humans, including food production, recreation, water purification, navigation and amenity. Various groups of stakeholders all place different importance on these values, how their needs and practices interact, and what it means to effectively manage an estuary towards a range of desirable goals. This typically creates value conflicts over how estuaries should be managed. Navigating such conflicts requires governance arrangements and methods that allow multiple parties to find a common path forward. Using Evolutionary Governance Theory (EGT) and a hybrid analytic framework incorporating aspects of multilevel/multi-scalar governance, risk governance and territorial intelligence theory, this paper explores the (co-) evolution of governance processes by analysing lessons learnt from action in and observation of estuaries in Australia (Lower Hawkesbury), France (Thau) and New Caledonia (Thio). A multi-method research approach to data collection was used and comparative analysis across the three estuaries undertaken to understand the evolutions in each of their governance systems. From this analysis, several reflections and lessons for the governance of other land-sea systems emerge on: the importance of boundary organisations and boundary negotiations in re-defining integrated approaches to land-sea governance; how particular information systems or models, as well as discourses from other key actors shape co-evolutions of estuarine governance; and that risks or shocks still appear to be the catalysers of new forms of collective action and major reconfigurations and evolutions of estuarine governance
Multiplicity of asymptomatic Plasmodium falciparum infections and risk of clinical malaria : a systematic review and pooled analysis of individual participant data
No full textBackground. The malaria parasite Plasmodium falciparum holds an extensive genetic polymorphism. In this pooled analysis, we investigate how the multiplicity in asymptomatic P. falciparum infections-that is, the number of coinfecting clones-affects the subsequent risk of clinical malaria in populations living under different levels of transmission. Methods. A systematic search of the literature was performed to identify studies in which P. falciparum infections were genotyped in asymptomatic individuals who were followed up prospectively regarding the incidence of clinical malaria. Individual participant data were pooled from 15 studies (n = 3736 individuals). Results. Multiclonal asymptomatic infections were associated with a somewhat increased subsequent risk of clinical malaria in the youngest children, followed by an initial declining risk with age irrespective of transmission intensity. At approximately 5 years of age, the risk continued the gradual decline with age in high-transmission settings. However, in older children in moderate-, low-, and seasonal-transmission settings, multiclonal infections were either not significantly associated with the risk of subsequent febrile malaria or were associated with an increased risk. Conclusions. The number of clones in asymptomatic P. falciparum infections is associated with different risks of subsequent clinical malaria depending on age and transmission intensity
May passive dispersal of fungal enemies with native substrates in olive nurseries help to control phytonematodes ?
No full textDescription of the subject. In Morocco, expanding agricultural sector under "Morocco Green Plan" will also introduce plant diseases and plant parasitic nematodes (PPN). Soil substrate used in most of the olive nurseries is potentially inhabited by PPN and natural enemies. Objectives. This work assessed the co-occurrence of PPN and nematophagous fungi (NF) in substrates and potential of NF to suppress PPN. Method. The diversity of PPN and NF genera was characterized in 305 substrate samples, isolated from 25 olive nurseries and functional activity (nematicidal and enzymatic) of NF was evaluated. Results. High PPN diversity was detected in the isolated samples and substrates were differentiated by NF activity. Global partition between PPN and NF diversity patterns confirmed prey-predator antagonism. Moreover, PPN-NF patterns depend on the fungal survival (saprophytes vs obligate parasites) and antagonism (predation vs toxicity) processes. However, even the NF strains with maximum fitness (growth, sporulation, enzymatic activity) were not inevitably the most effective against PPN. Consequently, it was hypothesized that predation and competition could be an adaptation process of NF to overcome environmental stress and exploit alternative or supplementary nutrient sources. Conclusions. The use of diverse native NF from cultivated and wild soils offer future prospects for the development of PPN management strategies in olive nurseries
The delayed island mass effect : how islands can remotely trigger blooms in the oligotrophic ocean
No full textIn oligotrophic gyres of the tropical ocean, islands can enhance phytoplankton biomass and create hotspots of productivity and biodiversity. This "island mass effect" (IME) is typically identified by increased chlorophyll concentrations next to an island. Here we use a simple plankton model in a Lagrangian framework to represent an unexplained open ocean bloom, demonstrating how islands could have triggered it remotely. This new type of IME, termed "delayed IME," occurs when nitrate is limiting, N:P ratios are low, and excess phosphate and iron remain in water masses after an initial bloom associated with a "classical" IME. Nitrogen fixers then slowly utilize leftover phosphate and iron while water masses get advected away, resulting in a bloom decoupled in time (several weeks) and space (hundreds of kilometers) from island-driven nutrient supply. This study suggests that the fertilizing effect of islands on phytoplankton may have been largely underestimated
Aerobic release and biodegradation of dissolved organic matter from frozen peat : effects of temperature and heterotrophic bacteria
No full textUnderstanding the conditions of dissolved organic matter (DOM) release from thawing peat in the Arctic regions and identifying the pathways of processing DOM by soil and aquatic heterotrophic bacteria are critical in the context of rapid climate change. Until now, experimental approaches did not allow quantitative predictions of temperature and biota effects on carbon release from peat in permafrost-affected aquatic environments. In this study, we incubated frozen peat and its aqueous leachate at various temperatures (4, 25 or 45 degrees C), with and without culturable heterotrophic bacteria Iodobacter sp., extracted from thermokarst lakes, to quantify the release and the removal rate of organic carbon (OC) with time. The metabolic diversity of the native microbial community associated with the substrates involved in OC processing was also characterized. Transmission electron microscopy revealed that, after degradation, the associated bacteria are mostly located in the inner parts of plant cells, and that the degradation of organic matter around bacteria is more pronounced at 4 and 25 degrees C compared to 45 degrees C. The metabolic diversity of heterotrophic bacteria was equally high at 4 and 25 degrees C, but lower at 45 degrees C. Regardless of the microbial consortium (native community alone or with added culturable heterotrophs), both the OC release from peat and the OC removal from peat leachate by bacteria were similar at 4 and 25 degrees C. Very low apparent activation energies of DOM biodegradation between 4 and 25 degrees C (- 4.23 +/- 12.3 kJ mol(-1)) suggest that the short-period of surface water warming in summer would have an insignificant effect on DOM microbial processing. Such duration (1-3 weeks) is comparable with the water residence time in peat depressions and permafrost subsidences, where peat degradation and DOM microbial processing occur. This questions the current paradigm of a drastic effect of temperature rise on organic carbon release from frozen peatlands, and should be considered for modelling short-term climate impacts in these regions
Cross-tolerance for drought, heat and salinity stresses in chickpea (Cicer arietinum L.)
No full textChickpea crops are often exposed to a combination of drought, heat and salinity stresses during the reproductive stage. Previous efforts have largely focused on these stresses in isolation, such that we do not understand whether genotypes tolerant to one stress can withstand other stresses. Around 22-44 chickpea genotypes contrasting for tolerance to drought, salinity or heat in previous studies were exposed to terminal drought (TD, 3 experiments) and to salinity (SAL, 1 experiment). A priori stress tolerance to any of the listed stresses was generally reflected in drought and salinity tolerance in the present study. Thus, the drought-, heat- and salt-tolerant groups (DT, HT and ST) produced higher seed yield, had earlier phenology, higher harvest indices and seed yield transpiration efficiencies compared with sensitive groups (DS, HS and SS). However, tolerance did not select for prescriptive water use patterns. Despite our efforts to remove the confounding effects of phenology, 4-9 days variation in flowering time made a significant difference in productivity and differentiated tolerant from sensitive counterparts. In TD1, TD2 and SAL, all tolerant groups yielded similarly under stress conditions. This showed the existence of cross-tolerance in chickpea where tolerant genotype selected for an individual stress can yield well under other stresses too
Diversity and ecology of sand flies (Diptera: Psychodidae), potential vectors of Leishmania in the Quang Ninh Province, Vietnam
No full textThe study aims to make an update on the distribution and ecology of sand flies in the Quang Ninh province, Northern Vietnam, where Leishmania cases were reported in 2001. Seventeen sites were chosen in three districts of the province: Ha Long, Cam Pha, and Hoanh Bo. Phlebotomine sand flies were collected using 68 CDC light traps from May 30 to 3 June 2016. Captured specimens were transferred individually into Eppendorf tubes with 90% ethanol.The sand fly heads and genitalia were removed and were mounted in Euparal after successive different baths. Specimen identification was determined based on the morphology of the cibarium, pharynx, and/or male genitalia or female spermathecae. A total of 416 sand flies (125 females, 283 males) belonging to four genera were collected and 10 sand fly species were identified: Sergentomyia silvatica, Se. barraudi, Se. hivernus, Se. bailyi, Phlebotomus mascomai, Ph. stantoni, Ph. yunshengensis, Ph. betisi, Chinius junlianensis, Idiophlebotomus longiforceps.The Sergentomyia genus prevailed (79.7% of the collected sand flies), followed by the Phlebotomus genus (13.7%), the Chinius genus (6.1%), and the Idiophlebotomus genus (0.8%). Besides these well-defined taxa, five specimens, named sp1, showed unknown morphological characteristics, requiring further study. The majority of sand flies were collected in rock caves suggesting the cavernicolous character of the species in the Quang Ninh province. However, specimens were also collected in intra and peridomiciliary sites in which Ph. stantoni and Se. hivernus were found as the main species. It is worth noting that two Ph. stantoni were found in the house of a patient affected by Leishmania
An autonomous low-power instrument platform for monitoring water and solid discharges in mesoscale rivers
No full textWe present the development of the River Platform for Monitoring Erosion (RIPLE) designed for monitoring at high temporal frequency (similar to 10 min) of water discharge, solid fluxes (bedload and suspended load) and properties of fine particles (settling velocity) in mesoscale rivers, i.e. which drain mesoscale catchments (approximate to 10-10(3) km(2)). This platform responds to a request to continuously measure these variables in rivers using a single, centralized device, and to do this in the most direct way possible. The platform integrates the following instruments: (i) for water discharge, water level radar, and surface velocity radar, digital cameras and an echo sounder; (ii) for fine sediment load, turbidimeters and automatic samplers including the SCAF (a sediment settling velocity characterization device); (iii) for bedload, a hydrophone; and (iv) for water quality, a conductivity probe and water sampling. As far as water discharge monitoring is concerned, priority has been given to non-intrusive instruments to improve the robustness of the system. All the instruments are driven by a data logger (Campbell (R) CR6), which locally stores the data and then uploads them to a remote server every hour during the day using a 3G modem. SMS (Short Message Service) alerts can be sent depending on scheduled conditions (e.g. low battery voltage, water level threshold, all samples of the automatic sampler collected). The platform has been designed to be as autonomous as possible: it is powered by a battery that is supplied by a solar panel. Limiting the power consumption of the platform was one of the main technical challenges because of the quantity of instruments integrated. A simple 100W solar panel is sufficient to power the entire platform, even during winter or low insulation conditions. A user-friendly interface has been developed, enabling to visualize the data collected by the platform from an internet connection. It is also possible to remotely configure the platform within this interface, e.g. to modify water sampling thresholds or alert thresholds. Finally, the platform is relatively easy to move from one site to another, because its installation requires little civil engineering. To date, RIPLE has been tested on two rivers of the Alps in France: the Romanche river in Bourg d'Oisans from September 2016 to July 2018 and the Galabre river in La Robine sur Galabre since October 2018, demonstrating the proper functioning of the platform
Derivation of consistent, continuous daily river temperature data series by combining remote sensing and water temperature models
No full textScarcity of water temperature data in rivers may limit a diversity of studies considering this property, which regulates many physical, chemical, and biological processes. We present a robust method to generate a consistent, continuous daily river water temperature (RWT) data series for medium and large rivers using the combined techniques of remote sensing and water temperature modelling. In order to validate our approach, we divided this study into two parts: (i) we evaluated methods to derive RWT from Landsat 7 ETM+ and Landsat 8 TIRS imagery; and (ii) we evaluated the calibration and validation of river temperature models, using these data, to generate the continuous RWT data series. A 1.2 km section of the White River located near Hazleton, IN, USA, was selected to assess this method mainly due to river width and data availability. We tested three methods to retrieve RWT from Landsat 7 and four from Landsat 8, and we also applied a simple thermal sharpening technique. For Landsat 7, the methods showed bias and RMSE of 0.01-0.46 degrees C and 1.32-1.84 degrees C, while for Landsat 8, the methods showed bias and RMSE of 0.08-1.27 degrees C and 1.74-2.17 degrees C, and in both cases, the best results were found applying the radiative transfer equation with NASA's Atmospheric Correction Parameter Calculator. For the second part of the validation process, we compared a stochastic model and a hybrid model, air2stream, using as input two datasets: the RWT data derived from Landsat 7 only, and a combined dataset of both Landsat 7 and 8 derived RWT. The air2stream model outperformed the stochastic model when calibrated with Landsat 7 data only, with RMSE of 1.83 degrees C, but both models showed similar results when calibrated with the combined Landsat data, when air2stream showed RMSE of 1.58 degrees C. Due to its physical basis, better calibration procedure, and higher consistency, air2stream was considered the best model for deriving the continuous RWT data series. When compared to the measured daily mean RWT data, there was no observed tendency in under or overestimating the RWT in low or high temperature conditions by the modelled series. While further tests are needed in order to evaluate if our approach can be applied to analyse past behaviour and present trends, and the impacts of climate change on the temperature of rivers, the consistent results indicate that this approach has the potential to be applied in rivers with no measured temperature data, for example, in the spatial modelling of longitudinal profiles of rivers and the modelling of tributary river temperatures