Morphology of Gambierdiscus excentricus (Dinophyceae) with emphasis on sulcal plates

Gambierdiscus excentricus is an epibenthic dinoflagellate able to produce ciguatoxin and maitotoxin-like compounds that are responsible for ciguatera fish poisoning. Morphological descriptions and molecular characterization of two G. excentricus strains isolated from Brazil and maintained in culture were provided. The most complete description of the morphology of the sulcal region of Gambierdiscus based on light and scanning electron microscopy was presented. The sulcal area morphology and nomenclature used by different authors to name the sulcal plates in Gambierdiscus were reviewed. Two small sulcal plates (S.m.a. and S.m.p.) were shown for the first time. Phylogenetic trees based on D1–D3 and D8–D10 large subunits of ribosomal RNA gene sequences showed that the strains of G. excentricus from Brazil clustered with strains of G. excentricus isolated from its type locality, the Canary Islands. Both phylogenetic trees reconstructed the same relationships among all the formally described Gambierdiscus species and Gambierdiscus sp. ribotype 2 and Gambierdiscus sp. type 2.Versión del editor2,080

Por um paradigma transperiférico

Este texto propõe uma agenda de pesquisa sobre a produção de espaços de diálogo e solidariedade entre territórios periféricos. O termo ‘transperiferias’ traduz esta proposta de pesquisa e engajamento, elaborada coletivamente por sete pesquisadores/as situados/as no campo aplicado dos estudos da linguagem. A agenda das transperiferias oferece caminhos de ruptura com paradigmas que situam, de um lado, a produção de conhecimento sobre desigualdade e, de outro lado, os sujeitos e territórios que se engajam com a contestação dessa desigualdade a partir de posicionalidades marginais. Propõe-se, em outras palavras, uma aproximação entre a produção de saber “sobre” as periferias com a produção de conhecimento “das” periferias, ao mesmo tempo em que se projetam espaços de diálogo e reflexão “entre” periferias, regionais, nacionais e globais. O texto justapõe os tipos de engajamento e produção epistêmica de cada um/a dos/as pesquisadores/as, de modo a apontar para formas em que objetos de investigação, como letramentos, tradução, processos de racialização, enregistramento sociolinguístico, violência etc., podem ser revisitados numa visão transperiférica. Convidamos sujeitos de diferentes periferias, bem como campos epistêmicos diversos, a ampliarem e tensionarem essa agenda de investigação

Maitotoxin-4, a Novel MTX Analog Produced by Gambierdiscus excentricus

Maitotoxins (MTXs) are among the most potent toxins known. These toxins are produced by epi-benthic dinoflagellates of the genera Gambierdiscus and Fukuyoa and may play a role in causing the symptoms associated with Ciguatera Fish Poisoning. A recent survey revealed that, of the species tested, the newly described species from the Canary Islands, G. excentricus, is one of the most maitotoxic. The goal of the present study was to characterize MTX-related compounds produced by this species. Initially, lysates of cells from two Canary Island G. excentricus strains VGO791 and VGO792 were partially purified by (i) liquid-liquid partitioning between dichloromethane and aqueous methanol followed by (ii) size-exclusion chromatography. Fractions from chromatographic separation were screened for MTX toxicity using both the neuroblastoma neuro-2a (N2a) cytotoxicity and Ca2+ flux functional assays. Fractions containing MTX activity were analyzed using liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) to pinpoint potential MTX analogs. Subsequent non-targeted HRMS analysis permitted the identification of a novel MTX analog, maitotoxin-4 (MTX4, accurate mono-isotopic mass of 3292.4860 Da, as free acid form) in the most toxic fractions. HRMS/MS spectra of MTX4 as well as of MTX are presented. In addition, crude methanolic extracts of five other strains of G. excentricus and 37 other strains representing one Fukuyoa species and ten species, one ribotype and one undetermined strain/species of Gambierdiscus were screened for the presence of MTXs using low resolution tandem mass spectrometry (LRMS/MS). This targeted analysis indicated the original maitotoxin (MTX) was only present in one strain (G. australes S080911_1). Putative maitotoxin-2 (p-MTX2) and maitotoxin-3 (p-MTX3) were identified in several other species, but confirmation was not possible because of the lack of reference material. Maitotoxin-4 was detected in all seven strains of G. excentricus examined, independently of their origin (Brazil, Canary Islands and Caribbean), and not detected in any other species. MTX4 may therefore serve as a biomarker for the highly toxic G. excentricus in the Atlantic area

Phytoplankton blooms and water quality of the Fleet lagoon, Dorset, UK, including studies of isolated toxic strains of Alexandrium minutum and Prorocentrum lima

A two year survey (2000-2001) of the coastal Fleet lagoon, in Dorset, UK was performed with the aim of identifying the environmental conditions influencing the occurrence of phytoplankton blooms.  Measurements included phytoplankton species abundance, biomass and identification, chlorophyll-a concentration, high performance liquid chromatography (HPLC) determined pigment concentrations, nutrients, temperature, irradiance, salinity, and data from a local meteorological station.  Multivariate statistical methods (MDS and cluster analysis) were used to study temporal and spatial changes in species and environmental conditions.  The quantification of biotoxins responsible for paralytic shellfish poisoning (PSP) and diarrhetic shellfish poisoning (DSP) in shellfish samples acquired from the Fleet lagoon was performed during 2001.  The Abbotsbury embayment, at the brackish water end of the lagoon presented high levels of phytoplankton biomass, pigments and nutrients and may be considered eutrophic, in contrast to conditions observed in the east Fleet.  Blooms of cryptophytes were observed at Abbotsbury during spring in both years and were related to new nutrient inputs that occur during winter.  A bloom of the planktonic dinoflagellate Prorocentrum micans was observed in late summer-autumn 2000.  The balance between freshwater and marine inputs to the Fleet and suitable conditions of nutrients and temperature plus longer water retention times were important determinants of the P. micans blooms in the west Fleet.  Two toxic dinoflagellate species isolated from the Fleet lagoon were studied using laboratory cultures;  the epi-benthic Prorocentrum lima that causes DSP and the planktonic Alexandrium minutum, responsible for PSP.  DSP toxins were quantified using liquid chromatography linked to mass spectrometry (LC/MS) and PSP toxins using HPLC.   HPLC determined pigment profiles and measurements of nitrate and phosphate concentrations in the growth media provided estimates of nutrient uptake rates.</p

Phytoplankton blooms and water quality of the Fleet lagoon, Dorset, UK, including studies of isolated toxic strains of Alexandrium minutum and Prorocentrum lima

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Infância, experiência e etnografia na Educação Infantil

Este artigo faz parte dos resultados de uma pesquisa realizada no campo da educação que teve como objetivo investigar a “experiência da infância” de crianças matriculadas em instituições educacionais. O campo empírico foi construído a partir do banco de dados referente à observação em vinte e uma instituições de educação infantil de um grande centro urbano. O referencial teórico teve como base os estudos da sociologia e da antropologia da infância, campos que se dedicam ao conhecimento das crianças e suas culturas. Assim, ao eleger as crianças como sujeitos de investigação, este artigo pretende dar visibilidade ao que elas produzem em interação quando optamos pela etnografia como estratégia metodológica

Investigation of phagotrophy in natural assemblages of the benthic dinoflagellates Ostreopsis, Prorocentrum and Coolia

Abstract Mixotrophy has been shown to be a common trait among dinoflagellates and its importance in the nutritional ecology of harmful algae has been hypothesized. Benthic harmful species have not been extensively investigated as their planktonic counterparts and there are major gaps in the knowledge of their nutritional strategies. In this study the occurrence of phagotrophy was investigated in natural assemblages of benthic dinoflagellates using epi-fluorescence microscopy with DAPI and LysoSensor staining. The study was conducted at five sites along the coast of Rio de Janeiro that were visited in January, August and December 2010. In total, 1659 dinoflagellate cells were observed. From these, only 0.4% of 1195 Ostreopsis cf. ovata and 2.2% of 134 Coolia spp. cells presented evidence of phagotrophy with vacuoles stained by LysoSensor or a DAPI (4',6-diamidino-2-phenylindole) stained inclusion. Stained vacuoles were not registered in the 330 Prorocentrum spp. cells observed. Few O. cf. ovata cells contained round red inclusions ("red spots") that were not stained either by DAPI or LysoSensor, suggesting that these structures are not ingested prey. The results showed that phagotrophy was not a frequent nutritional strategy in benthic dinoflagellates during the study period