1,720,963 research outputs found
The role of wetland microinvertebrates in spreading human diseases
Get PDFThe increasing loads of anthropogenic pollutants, compounded with climate change events, are likely to induce environmental changes in many wetlands with impacts on the native microinvertebrates and pathogens causing increased occurrence of water-borne diseases, which affect millions of people each year. In wetlands bacterial pathogens are actively preyed on by many protozoa and filter-feeding organisms but this predation can be compensated by the nourishment and protection offered by certain microinvertebrates, acting as hosts, e.g., chitinous rotifers, copepods and cladocerans. The complex interactions of ecological, biological, and genetic components mediate disease-causing organisms to exploit microinvertebrate hosts to occupy diverse niches, obtain nutrition, and withstand physico-chemical stresses. The persistence of the human pathogens in wetlands is often enabled by their association with microinvertebrates and also depends on their quorum sensing mediated colonization, biofilm formation, switching into dormant stage, and horizontal transfer of adaptive genes. The symbiosis with microinvertebrates is facilitated by the pathogen’s immune evasion and fitness factors, e.g., Type-IV pili, capsular-polysaccharides, nutrient transportation, virulence and binding proteins, proteases, chitinases, and secretion systems. Spatio-temporal variation in the population of copepods and aquatic eggs/larvae of mosquitoes and midge flies, which act as vectors, can influence the outbreaks of cholera, diarrhea, malaria, dengue, filariasis and drucunculiasis. Changes in climatic factors (temperature, salinity, cyclones, rainfall, etc.) and anthropogenic pollutions (sewage, fertilizer and insecticide) may modify the abundance and biodiversity of microinvertebrates, and thus possibly exacerbate the persistence and dispersal of water-borne pathogens. Thus there is a need to adopt ecohydrological and eco-friendly interventions for managing wetlands while conserving them.Fil: Neogi, Sucharit Basu. International Centre For Diarrhoeal Disease Research; Bangladesh. Osaka Prefecture University; JapónFil: Yamasaki, Shinji. Osaka Prefecture University; JapónFil: Alam, Munirul. International Centre For Diarrhoeal Disease Research; BangladeshFil: Lara, Ruben Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto Argentino de Oceanografía (i); Argentina. Leibniz Centre for Tropical Marine Ecology; Alemani
Environmental and hydroclimatic factors influencing Vibrio populations in the estuarine zone of the Bengal delta
Get PDFThe objective of this study was to determine environmental parameters driving Vibrio populations in the estuarine zone of the Bengal delta. Spatio-temporal data were collected at river estuary, mangrove, beach, pond, and canal sites. Effects of salinity, tidal amplitude, and a cyclone and tsunami were included in the study. Vibrio population shifts were found to be correlated with tide-driven salinity and suspended particulate matter (SPM). Increased abundance of Vibrio spp. in surface water was observed after a cyclone, attributed to re-suspension of benthic particulate organic carbon (POC), and increased availability of chitin and dissolved organic carbon (DOC). Approximately a two log10 increase in the (p 60 μm fractions. Benthic and suspended sediment comprised a major reservoir of Vibrio spp. Results of microcosm experiments showed enhanced growth of vibrios was related to concentration of organic matter in SPM. It is concluded that SPM, POC, chitin, and salinity significantly influence abundance and distribution of vibrios in the Bengal delta estuarine zone.Fil: Neogi, Sucharit Basu. Osaka Prefecture University; Japón. International Centre for Diarrhoeal Disease Research; BangladeshFil: Lara, Ruben Jose. Leibniz Center for Tropical Marine Research; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Alam, Munirul. International Centre for Diarrhoeal Disease Research; BangladeshFil: Harder, Jens. Max Planck Institute for Marine Microbiology; AlemaniaFil: Yamasaki, Shinji. Osaka Prefecture University; JapónFil: Colwell, Rita R.. University of Maryland; Estados Unidos. University Johns Hopkins; Estados Unidos. CosmosID, Inc.; Estados Unido
Seasonal dynamics of Vibrio cholerae and its phages in riverine ecosystem of Gangetic West Bengal: cholera paradigm
Get PDFThe Gangetic delta is a century-old cholera endemic belt where the role of riverine–estuarine ecosystem in cholera transmission has never been elucidated. Seasonality, distribution, and abundance of environmental Vibrio cholerae O1/O139 and vibriophage in Hooghly riverine–estuarine environment and their correlation with cholera incidence pattern in West Bengal, India, have been analyzed for the first time across summer, monsoon, and winter months. A total of 146 water samples collected from two sites of the Hooghly River (Howrah and Diamond Harbour) were analyzed physicochemically along with cultivable Vibrio count (CVC), V. cholerae O1/O139, and vibriophages. V. cholerae O1 was detected in 56 (38.3 %) samples, while 66 (45.2 %) were positive for V. cholerae O1 phages. Flood tide, water temperature (31 ± 1.6 °C), and turbidity (≥250 nephelometric turbidity unit (NTU)) significantly stimulated V. cholerae and vibriophage abundance in riverine ecosystem. Solitary existence of V. cholerae O1 and phages (p < 0.0001) in aquatic environment divulges the dominance of either of the entity (V. cholerae O1 or V. cholerae O1 Φ) on the other. Significant association (p < 0.05) between Kolkata cholera cases and V. cholerae O1 in aquatic environment implies the role of riverine–estuarine ecosystem in cholera transmission. A “biomonitoring tool” of physicochemical stimulants, tidal, and climatic variants has been proposed collating V. cholerae and phage dynamics that can forewarn any impending cholera outbreak.Fil: Mookerjee, Subham. National Institute For Cholera And Enteric Diseases; IndiaFil: Jaiswal, Abhishek. National Institute For Cholera And Enteric Diseases; IndiaFil: Batabyal, Prasenjit. National Institute For Cholera And Enteric Diseases; IndiaFil: Einsporn, Marc H.. Centre For Tropical Marine Ecology; AlemaniaFil: Lara, Ruben Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto Argentino de Oceanografía (i); Argentina. Centre For Tropical Marine Ecology; AlemaniaFil: Sarkar, Banwarilal. National Institute For Cholera And Enteric Diseases; IndiaFil: Neogi, Sucharit Basu. Osaka Prefecture University; Japón. International Centre for Diarrheal Disease Research; BangladeshFil: Palit, Anup. National Institute For Cholera And Enteric Diseases; Indi
Occurrence and distribution of plankton-associated and free-living toxigenic Vibrio cholerae in a tropical estuary of a cholera endemic zone
Get PDFCholera epidemics are thought to be influenced by changes in populations of estuarine Vibrio cholerae. We investigated the abundance and distribution of this bacterium, as ‘‘free-living’’ (\20 lm fraction) and associated with microphytoplankton ([20 lm) or zooplankton ([60 lm), in the Karnaphuli estuary of Bangladesh during pre- and post-monsoon seasons. Cultivable Vibrio populations were *102 –104 colony forming units (CFU) ml-1 in the high saline zone (19–23 practical salinity unit, PSU) and declined in freshwater (\101 CFU ml-1 ). Culture independent detection of toxigenic V. cholerae O1 and O139 serogroups revealed a higher abundance of ‘‘free-living’’ (104 –105 cells l-1 ) than those attached to plankton (101 –103 cells l-1 ). However, ‘‘free-living’’ O1 and O139 cells were sometimes absent in the medium saline and freshwater areas (0.0–11 practical salinity unit [PSU]). In contrast, plankton samples always harbored these serogroups despite changes in salinity and other physico-chemical properties. Microphytoplankton and zooplankton were dominated by diatoms and blue-green algae, and copepods and rotifers, respectively. Toxigenic V. cholerae abundance did not correlate with plankton abundance or species but had a positive correlation with chitin in the\20 lm fraction, where suspended particulate matter (SPM), V. cholerae and chitin concentrations were highest. C:N ratios indicated that organic matter in SPM originated predominantly from plankton. The differential occurrence of ‘‘free-living’’ and attached V. cholerae suggests a pivotal function of plankton in V. cholerae spreading into freshwater areas. The probable association of this pathogen with organisms and particles in the nanoplankton (\20 lm) fraction requires validation of the concept of the ‘‘free living’’ state of V. cholerae in aquatic habitats.Fil: Neogi, Sucharit Basu. Osaka Prefecture University; Japón. International Centre for Diarrhoeal Disease Research; BangladeshFil: Islam, Mohammad Sirajul. International Centre for Diarrhoeal Disease Research; BangladeshFil: Nair, Balakrish Gopinath. National Institute of Cholera and Enteric Diseases; IndiaFil: Yamasaki, Shinji. Osaka Prefecture University; JapónFil: Lara, Ruben Jose. Leibniz Centre for Tropical Marine Ecology GmbH; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentin
Sundarban mangroves: diversity, ecosystem services and climate change impacts
Get PDFThe Bengal delta coast harboring the famous Sundarban mangroves is extremely vulnerable to climate change. Already, salinity intrusion, increasing cyclones and anomalies in rainfall, and temperature, are causing many social and livelihood problems. However, our knowledge on the diversified climate change impacts on Sundarban ecosystems services, providing immense benefits, including foods, shelters, livelihood, and health amenities, is very limited. Therefore, this article has systematically reviewed the major functional aspects, and highlights on biodiversity, ecosystem dynamics, and services of the Sunderban mangroves, with respect to variations in climatic factors. The mangrove ecosystems are highly productive in terms of forest biomass, and nutrient contribution, especially through detritus-based food webs, to support rich biodiversity in the wetlands and adjacent estuaries. Sundarban mangroves also play vital role in atmospheric CO2 sequestration, sediment trapping and nutrient recycling. Sea level rise will engulf a huge portion of the mangroves, while the associated salinity increase is posing immense threats to biodiversity and economic losses. Climate-mediated changes in riverine discharge, tides, temperature, rainfall and evaporation will determine the wetland nutrient variations, influencing the physiological and ecological processes, thus biodiversity and productivity of Sundarban mangroves. Hydrological changes in wetland ecosystems through increased salinity and cyclones will lower the food security, and also induce human vulnerabilities to waterborne diseases. Scientific investigations producing high resolution data to identify Sundarban‟s multidimensional vulnerabilities to various climatic regimes are essential. Sustainable plans and actions are required integrating conservation and climate change adaptation strategies, including promotion of alternative livelihoods. Thus, interdisciplinary approaches are required to address the future climatic disasters, and better protection of invaluable ecosystem services of the Sunderban mangroves.Fil: Neogi, Sucharit Basu. Coastal Development Partnership; Bangladesh. Osaka Prefecture University; Japón. Leibniz Center for Tropical Marine Ecology GmbH; AlemaniaFil: Dey, Mouri. University of Chittagong; BangladeshFil: Lutful Kabir, S. M.. Bangladesh Agricultural University; BangladeshFil: Masum, Syed Jahangir H.. Coastal Development Partnership; BangladeshFil: Kopprio, Germán Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina. Leibniz Center for Tropical Marine Ecology GmbH; AlemaniaFil: Yamasaki, Shinji. Osaka Prefecture University; JapónFil: Lara, Ruben Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentin
Occurrence, survival and diversity of vibrios along a gradient of brackish to freshwater in Karnaphuli river estuary, Bangladesh
No full textBiogeochemical and hydrological drivers of the dynamics of Vibrio species in two Patagonian estuaries
Get PDFThe ecology of the most relevant Vibrio species for human health and their relation to water quality and biogeochemistrywere studied in two estuaries in Argentinian Patagonia. Vibrio cholerae and Vibrio parahaemolyticuswere reported in N29% of cases at the Río Colorado and Río Negro estuaries. Neither the pandemic serogroupsof Vibrio cholerae O1, Vibrio cholerae O139 nor the cholera toxin gene were detected in this study. However, severalstrains of V. cholerae (not O1 or O139) are able to cause human disease or acquire pathogenic genes by horizontaltransfer. Vibrio vulnificus was detected only in three instances in the microplankton fraction of the RíoNegro estuary. The higher salinity in the Río Colorado estuary and in marine stations at both estuaries favoursan abundance of culturable Vibrio. The extreme peaks for ammonium, heterotrophic bacteria and faecal coliformsin the Río Negro estuary supported a marked impact on sewage discharge. Generally, the more pathogenic strainsof Vibrio have a faecal origin. Salinity, pH, ammonium, chlorophyll a, silicate and carbon/nitrogen ratio ofsuspended organic particulates were the primary factors explaining the distribution of culturable bacteria afterdistance-based linear models. Several effects of dissolved organic carbon on bacterial distribution are inferred.Fil: Kopprio, Germán Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina. Leibniz Center for Tropical Marine Ecology; AlemaniaFil: Streitenberger, Maria Eugenia. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; ArgentinaFil: Okuno, Kentaro. Osaka Prefecture University; JapónFil: Baldini, Monica Diana. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; ArgentinaFil: Biancalana, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Fricke, Anna Lena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina. Leibniz Center for Tropical Marine Ecology; AlemaniaFil: Martínez, Ana María. Universidad Nacional del Sur; ArgentinaFil: Neogi, Sucharit Basu. Osaka Prefecture University; JapónFil: Koch, Boris Peter. Alfred Wegener Institute Helmholtz Center for Polar and Marine Research; AlemaniaFil: Yamasaki, Shinji. Osaka Prefecture University; JapónFil: Lara, Ruben Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentin
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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