19 research outputs found

    Ecological assessment of wetland ecosystems of northern Kazakhstan on the basis of hydrochemistry and algal biodiversity

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    We studied diversity of algae and cyanobacteria in the wetlands of protected natural lakes with salinity ranging from 0.19 up to 32.7 in the arid/semiarid regions of Northern Kazakhstan. In plankton and periphyton of 34 lakes, we found 254 species belonging to 113 genera of 8 algal divisions. The diversity in arid regions is represented by widespread species of diatoms, green algae, and cyanobacteria in similar proportions. Alkaliphiles, among the indicators of acidification, and betamesosaprobionts, among the indicators of saprobity, predominated. The indices of saprobity in lakes varied from 1.47 to 2.7, reflecting low-trophic and low anthropogenically disturbed wetlands. Oligohalobes- -indifferents are most common. Highly diverse algal communities were found irrespective of various levels of mineralization. As a consequence of aridization, salinity increase suppressed algal diversity. The mineralization was the most important variable defining the diversity levels, irrespective of the type and location of wetland lakes in the arid regions

    Aspectos ecológicos, taxonómicos y de distribución de cianobacterias bentónicas en cinco ríos de la región central de México

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    Antecedentes y Objetivos: Las cianobacterias son algas procariontes oxifot√≥trofas presentes en gran variedad de h√°bitats y son componentes importantes de las comunidades bent√≥nicas en muchos ambientes continentales y marinos. En M√©xico su diversidad en r√≠os es poco conocida; por ello, este estudio contribuye al conocimiento ficoflor√≠stico en cinco r√≠os de la regi√≥n central de M√©xico. Se incluyen descripciones e ilustraciones, estimaciones de su diversidad, un an√°lisis de las relaciones entre formas de crecimiento y factores microambientales, y se discute la validez de su caracterizaci√≥n morfol√≥gica y ecol√≥gica en la delimitaci√≥n de las especies encontradas. M√©todos: Se realizaron muestreos en secas y lluvias en dos r√≠os sil√≠ceos y tres r√≠os calc√°reos del centro de M√©xico. Se registr√≥ la temperatura del agua, conductividad espec√≠fica y pH, se analizaron iones mayores (Ca2+, Mg2+, K+, Na+, Si-SiO2, HCO3-, Cl-, SO43-) y nutrientes (NH4+, NO2-, NO32-, PO43-), se estim√≥ la diversidad de las cianobacterias registradas con el √≠ndice de Shannon-Weaver y se describieron sus h√°bitats y microh√°bitats. La identificaci√≥n taxon√≥mica se realiz√≥ utilizando literatura especializada. Resultados clave: Se identificaron cuatro asociaciones y nueve especies pertenecientes a tres √≥rdenes, siete familias y siete g√©neros. Se distinguieron dos grupos: el formado por Nostoc parmelioides-Coleodesmium wrangelii y Phormidium lividum-Leptolyngbya truncata en r√≠os sil√≠ceos de monta√Īa y el compuesto por Schizothrix mexicana-Phormidium subfuscum, Homoeothrix juliana-Heteroleibleinia fontana y Nostoc verrucosum en r√≠os calc√°reos c√°lidos. Se reconocieron dos patrones de distribuci√≥n ecol√≥gica: 1) las especies del orden Nostocales presentes en condiciones estresantes de luz y velocidad de corriente y 2) los taxa de los √≥rdenes Oscillatoriales y Synechococcales registrados en sitios con valores promedio de luz y flujo de agua. Conclusiones: La caracterizaci√≥n morfol√≥gica y ecol√≥gica de especies de cianobacterias contribuye a su conocimiento ficoflor√≠stico y es la base para futuras investigaciones sobre taxonom√≠a, sistem√°tica y uso sustentable de recursos algales.Background and Aims: Cyanobacteria are oxyphototrophic prokariotic algae present in great variety of habitats and they are important components of the benthic communities in many continental and marine environments. In Mexico, their diversity in streams is less known; therefore, this study contributes to phycofloristic knowledge in five streams of the central region of Mexico. Descriptions and illustrations, estimations of their diversity, an analysis of the relationships between growth forms and microenvironmental factors are included, and the validity of their morphological and ecological characterization in the delimitation of the species found is discussed. Methods: Sampling was carried out in dry and rainy seasons in two siliceous streams and three calcareous streams of central Mexico. Water temperature, specific conductivity and pH were recorded, major ions (Ca2+, Mg2+, K+, Na+, Si-SiO2, HCO3-, Cl-, SO43-) and nutrients (NH4+, NO2-, NO32-, PO43-) were analyzed, the diversity was estimated of the cyanobacteria registered with the Shannon-Weaver index, and their habitats and microhabitats were described. Taxonomic identification was carried out with specialized literature. Key results: Four associations and nine species belonging to three orders, seven families and seven genera were identified. Two groups were distinguished: one formed by Nostoc parmelioides-Coleodesmium wrangelii, Phormidium lividum-Leptolyngbya truncata in siliceous and mountain streams, and one composed by Schizothrix mexicana-Phormidium subfuscum, Homoeothrix juliana-Heteroleibleinia fontana and Nostoc verrucosum in calcareous, warm streams. Two ecological distribution patterns were recognized: 1) the Nostocales species present in stressful conditions of light and current velocity and 2) the taxa of Oscillatoriales and Synechoccales registered in sites with mean values of light and water flow. Conclusions: Morphological and ecological characterization of cyanobacterial species contributes to their phycofloristic knowledge and the base for future research on taxonomy, systematics and sustainable use of algal resources

    Toxic cyanobacteria from the territory of the Republic of Serbia

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    Ispitano je prisustvo toksińćnih cijanobakterija u razlińćitim ekosistemima sa teritorije¬†Republike Srbije i analizirane su negativne posledice koje mogu da prouzrokuju ovi¬†mikroorganizmi. Formirana je Baza podataka cijanobakterija u Srbiji koja prilaŇĺe veliki broj bitnih¬† i korisnih informacija iz preko 70 literaturnih izvora o prostiranju i uńćestalosti pojave cijanobakterija i njihovih toksina u periodu od 130 godina, kao i njihovih efekata na Ňĺivi svet u vodenim ekosistemima, ali i Ň°ire. IstraŇĺivana su 64 vodena ekosistema, ukljuńćujuńái reke, jezera, bare, kanale, ribnjake, akumulacije za navodnjavanje, akumulacije za snabdevanje vodom za pińáe i akumulacije sa drugom namenom, gde je najńćeŇ°ńáe cvetalo pet vrsta cijanobakterija i to:¬† Microcystis aeruginosa,¬† Aphanizomenon flos-aquae,¬† Planktothrix agardhii,¬† Microcystis flos-aquae¬† i¬† Planktothrix rubescens¬† koje ujedno i Ň°ire svoj areal rasprostranjenja na teritoriji Republike Srbije. U brojnim vodenim telima detektovani su mikrocistini i to u visokim koncentracijama. IstraŇĺivanje vodenog ekosistema LudoŇ° sa teritorije Republike Srbije vrŇ°eno je da bi se ustanovilo prisustvo i uticaj cijanobakterija i cijanotoksina na druge biljne i Ňĺivotinjske organizme u prirodnim uslovima. Trofińćki status jezera LudoŇ° najńćeŇ°ńáe je eutrofan, a cvetanje cijanobakterija kontinuirano joŇ° od 1970. godine. Tokom 2011. i 2012. godine¬† vrste Limnothrix¬† redekei¬† i¬† Pseudanabaena¬† limnetica¬† nańĎene¬† u¬† cvetanju. Detektovano je i prisustvo mikrocistina/nodularina i saksitoksina u biomasi i vodi, a mikrocistini su detektovani i u tkivu vodenih biljaka (trske¬† Phragmites communis, rogoza¬† Typha latifolia¬† i ljubińćastog lokvanja Nymphaea elegans) i ribi (Carassius gibelio) iz jezera LudoŇ°. HistoloŇ°kim pregledom tkiva ribe¬† pronańĎene su naizraŇĺenije promene u jetri, bubrezima i Ň°krgama, a primeńáene su i na crevima. Testiranjem bioloŇ°kih lesnih pokorica sa teritorije Vojvodine nisu detektovani¬†mikrocistini/nodularini, a nije detektovana ni toksińćnost uzoraka. Pretpostavlja se da su koncentracije cijanotoksina ispod granica detekcije ili ih nema u testiranim bioloŇ°kim lesnim pokoricama. Razvojem novih metoda i optimizacijom postojeńáih za detekciju cijanotoksina u bioloŇ°kim lesnim pokoricama i drugim terestrińćnim ekosistemima potrebno je proveriti dobijene rezultate. Prouńćavanjem svojstva 84 soja cijanobakterija iz NSCCC, koji potińću iz terestrińćnih i¬†vodenih ekosistema sa teritorije Republike Srbije, dobijena je intracelularna toksińćnost u eksponencijalnoj i stacionarnoj fazi rasta, kao i ekstracelularna toksińćnost ¬†kod jednog soja koji potińće sa terestrińćnog ekosistema. Dobijeni su i pozitivni rezultati ¬†na prisustvo mikrocistina, nodularina ili/i saksitoksina kod 34,1% terestrińćnih i 55,5% vodenih sojeva koji potińću sa teritorije Republike Srbije. Rezultati ukazuju na¬† potencijalnu opasnost pojave ovih¬† mikroorganizama i njihovih toksińćnih metabolita u razlińćitim ekosistemima sa teritorije Republike Srbije. Eksperimentalno je potvrńĎena akumulacija mikrocistina u rańćińáu¬† Daphnia pulex¬† usled ishrane toksińćnim sojem iz NSCCC, zbog ńćega upotreba ove vrste rańćińáa u izvońĎenju bioloŇ°kih testova za testiranje prisustva cijanotoksina treba da se preispita.¬† ҆taviŇ°e, veliki broj jedinki dafnija (92,2%) koristio je istraŇĺivane sojeve iz NSCCC za ishranu, odnosno ishrana je bila moguńáa sa svim vodenim i sa gotovo 90% terestrińćnih sojeva, Ň°to moŇĺe posluŇĺiti kao osnov za dalja istraŇĺivanja prevencije cvetanja. S obzirom na moguńánost ishrane rańćińáa¬† Daphnia¬† sp. cijanobakterijama, kompleks¬† ribnjaka sa teritorije Republike Srbije koriŇ°ńáen je za istraŇĺivanje potencijalnog nańćina¬† prevencije pojave i cvetanja cijanobakterija u zavisnosti od pravovremenog unoŇ°enja¬† pomenutog rańćińáa. Na osnovu koncentracije hlorofila¬† a¬† i trofińćkog statusa,¬† kvalitativne i kvantitativne analize cijanobakterija, toksińćnosti vode¬† i prisustva cijanotoksina mikrocistina/nodularina i saksitoksina, potvrńĎeno je smanjenje cvetanja cijanobakterija i drugih negativnih efekata u eksperimentalnim jezerima u odnosu na kontrolna. Ukoliko pak dońĎe do cvetanja i proizvodnje toksina¬† ijanobakterija u vodenim ekosistemima, zbog ozbiljnost pojave i moguńáih negativnih posledica po zdravlje ljudi, neohodno je uvesti postupke eliminacije ńáelija¬† cijanobakterija i njihovih ¬†toksina u praksu pri obradi¬† otpadnih voda i preńćiŇ°ńáavanja vode iz povrŇ°inskih akumulacija u Republici Srbiji.The presence of toxic¬† cyanobacteria in different ecosystems from the territory of the Republic of Serbia was analyzed as well as the negative consequences that may be causeed by these microorganisms. Serbian Cyanobacterial Data Base was formed where great number of important and useful information from over 70 literary sources regarding the distribution and frequency of cyanobacteria and their toxins over a period of 130 years, as well as their effects on wildlife in aquatic ecosystems, and beyond was presented. The study consisted of 64 aquatic ecosystems, including rivers, lakes, ponds, canals, irrigation reservoirs, reservoirs for drinking water supply and reservoirs with other purpose, where five species of cyanobacteria Microcystis aeruginosa,¬† Aphanizomenon flos-aquae,¬† Planktothrix agardhii,¬† Microcystis flosaquae¬† and¬† Planktothrix rubescens¬† frequently bloomed, and also expanded their area of distribution on the territory of the Republic of Serbia. In many water bodies microcystins were detected in high concentrations. Research into aquatic ecosystem LudoŇ°, located on the territory of the Republic of Serbia, was performed in order to determine the presence and effect of cyanobacteria and cyanotoxins on other plant and animal organisms in natural conditions. Trophic status of¬† the lake LudoŇ° was usually eutrophic, and cyanobacteria bloom is constant since 1970. During 2011 and 2012, the species Limnothrix¬† redekei¬† and¬† Pseudanabaena¬† limnetica¬† were found in blooming. Presence of microcystins/nodularin and saxitoxin was detected in¬† biomass and water, and microcystins were detected in tissues of aquatic plants (reed Phragmites communis, cattail¬†Typha latifolia¬†and royalblue waterlily¬† Nymphaea elegans) and fish (Carassius gibelio) from the lake LudoŇ°. Histological examination of tissue showed most prominent changes in liver, kidney and gills, and alterations were also observed in the intestine. Testing of the biological loess crust from Vojvodina showed no presence of microcystins/nodularin and toxicity of samples was not detected as well. It is assumed that cyanotoxin concentrations were below detection limit or are absent from the tested biological loess crusts. The development of new methods and optimization of existing ones for detection of cyanotoxins in biological loess crustsand¬† other terrestrial ecosystems is necessary in order to revise obtained results. Research of the properties from 84 strains of cyanobacteria from NSCCC originating¬†from terrestrial and aquatic ecosystems from the territory of the Republic of ¬†Serbia, resulte d inintracellular toxicity in exponential and stationary growth phase, as ¬†well as extracellular toxicity of a strain originating from terrestrial ecosystems. The obtained results were positive for the presence of microcystins, nodularin and/or saxitoxin¬† for 34.1% terrestrial and 55.5% aquatic strains originating from the territory of the Republic of Serbia. These results demonstrate the potential risk of occurrence of these microorganisms and their metabolites in different ecosystems from the territory of the Republic of Serbia. Accumulation of microcystins in shrimp Daphnia pulex¬†after feeding with toxic strain¬†from NSCCC was experimentally confirmed, indicating that the use of this species of shrimp in biological tests which determine the presence of cyanotoxins needs to be revisited. Moreover, a large number of¬†Daphnia¬† individuals (92.2%) used the investigated strains of NSCCC for food, and the feeding was possible with all ¬†the water strains and nearly 90% of terrestrial strains, which can serve as a basis for further research of bloom prevention. With regard to the possibility shrimp Daphnia¬†sp. feeding with cyanobacteria, a¬†complex of ponds from the territory of the Republic of Serbia was used to explore ¬†potential ways of prevention the occurrence and blooming of cyanobacteria, depending on the timely introduction of the aforementioned shrimp. Based on the concentrations of chlorophyll¬† a¬† and trophic status, qualitative and quantitative analysis of cyanobacteria, the toxicity of water and the presence of¬† cyanotoxins microcystins/nodularin and saxitoxin, reduction in blooming cyanobacteria and other negative effects in the experimental lakes when compared to the control lakes was confirmed. If the blooming regardless occurres as well as production of cyanobacterial ¬†toxins in aquatic ecosystems, due to the seriousness of the phenomenon and the possible negative consequences for human health, it would be necessary to introduce ¬†procedures for the elimination of cells of cyanobacteria and their toxins into practice in waste water treatment and purification of water from surface reservoirs in the Republic of Serbia

    Evaluación del perfil metabólico de un consorcio de cianobacterias bentónicas arrecifales del Caribe colombiano bajo condiciones cultivo

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    Las cianobacterias bent√≥nicas marinas son una fuente promisoria de compuestos estructuralmente complejos y con actividades biol√≥gicas de inter√©s. Entre estas, la actividad insecticida es de gran importancia en los sectores de salud p√ļblica y la agricultura, por lo cual ofrece grandes oportunidades de desarrollo comercial. Con el fin de aprovechar el potencial biotecnol√≥gico que estos organismos pueden ofrecer, se establecieron cultivos de 19 consorcios microbianos obtenidos a partir de tapetes de cianobacterias bent√≥nicas del Caribe colombiano. El medio de cultivo SWBG-11 modificado proporcion√≥ la fuente de hierro Fe(III)EDTA en lugar de citrato f√©rrico am√≥nico. Esta formulaci√≥n increment√≥ la solubilidad y subsecuente biodisponibilidad del hierro, promoviendo as√≠ el crecimiento de los consorcios. Cinco consorcios fueron efectivamente resuspendidos en vol√ļmenes mayores de cultivo, en el menor tiempo posible y sin observarse indicios de lisis celular. Los extractos crudos de tres de ellos (CB05, CB06 y CB16) resultaron activos en los ensayos de ecotoxicidad contra Artemia salina. De otro lado, el extracto crudo del consorcio CB09 mostr√≥ baja letalidad contra A. salina y actividad larvicida frente al mosquito vector de enfermedades Aedes aegypti. Se considera a este consorcio como una posible fuente promisoria de compuestos con actividad insecticida. Los cambios en las concentraciones de f√≥sforo, hierro y nitr√≥geno en el medio de cultivo SWBG-11, tuvieron un efecto en el perfil metab√≥lico del consorcio CB09. Las condiciones de limitaci√≥n y depleci√≥n de nutrientes incrementaron la producci√≥n de los compuestos C1 (tr 7,6 min; m/z 515,314) y C2 (tr 8,7 min; m/z 593,282), y propiciaron la bios√≠ntesis de los compuestos C7 (tr 9,8 min; m/z 282,276) y C8 (tr 14,0 min; m/z 621,448). El an√°lisis multivariante S-plot sugiere que todos ellos se encuentran relacionados con un incremento de la actividad larvicida de los extractos frente al mosquito Aedes aegypti.Abstract. Marine benthic cyanobacteria are a promising source of bioactive structurally complex compounds. The insecticide activity is of great importance in public health and agriculture, offering great opportunities for commercial development. In order to take advantage of their biotechnological potential, cultures of 19 benthic cyanobacterial consortia from the Colombian Caribbean were performed. The modified culture medium SWBG-11 provided the Fe(III)EDTA iron source instead ferric ammonium citrate. This formulation increased the solubility and subsequent bioavailability of iron, thus promoting the consortial growth. Five consortia were effectively resuspended in larger volumes of culture, in the shortest time, and without cell lysis clues. The crude extracts of three of them (CB05, CB06 and CB16) were active against Artemia salina in the ecotoxicity tests. On the other hand, the crude extract of the CB09 consortium showed the lowest lethality against A. salina in the ecotoxicity tests, and larvicidal activity against the mosquito vector of diseases Aedes aegypti. This consortium was considered as a possible promising source of compounds with insecticidal activity. Changes in phosphorus, iron and nitrogen concentrations in the SWBG-11 medium, influenced the metabolic profile of the CB09 consortium. Limitation and supression conditions of these nutrients increased the production of C1 and C2 compounds (rt 7.6 min; m/z 515.314 and rt 8.7 min; m/z 593.282), and propitiated the biosynthesis of C7 and C8 ones (rt 9.8 min; m/z 282.276 and rt 14.0 min; m/z 621.448). The multivariate analysis S-plot suggested that all of them are related to the larvicidal activity increasing of the crude extracts against Aedes aegypti.Maestr√≠

    Distribution and characterization of bacterial communities in diverse Antarctic ecosystems by high-troughput sequencing

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    Geological events and historical climate changes have eliminated or reduced most life in Antarctica to mainly microbial organisms in relatively simple communities. Due to its exceptional location, millennia long isolations and extreme climatic conditions, the continent offers a spectacular and unique background for fundamental scientific research and the testing of hypotheses. Notwithstanding the fact that Antarctica is still considered by many to be one of the last pristine environments on Earth, it is not only threatened by climate change, which particularly has severe effects on parts of West and Maritime Antarctica, but also by an ever increasing number of tourists and even scientists themselves. Studies on Antarctic biota are relatively scarce, and despite the fact that bacteria are fundamental to the Antarctic ecosystems, only a minority of the studies focus on these organisms. This results in a lacuna in the knowledge about the diversity, distribution and functioning of and the relationships between these organisms under the extreme Antarctic conditions. The recent advent of High-throughput sequencing (HTS) applications enables to sequence millions of DNA-fragments in a very short time, allowing us to visualise bacterial communities at a very high resolution, without the necessity for prior isolation of the organisms. In this PhD-study, we have applied some of these new technologies in order to investigate the bacterial diversity of different habitats throughout the Antarctic. In a first study (Chapter 2), we have compared the results obtained by pyrosequencing and compared these with the results of a previous isolation campaign. As expected, a much larger diversity of bacteria were found with pyrosequencing. While five bacterial phyla were recovered by cultivation, this was the case for 22 phyla with the NGS-approach, and a large amount of unknown diversity was evident. At the same time, it became clear that also the part of the 16S rRNA gene that was sequenced had an impact on the perceived diversity, with the V1-V2 fragments resulting in ~50% more OTUs than the V3-V2 fragments and only a limited amount of overlap in the genera recovered was noticed. In contrast, more chimeric sequences were identified in the V3-V2 amplicons. Notwithstanding the fact that pyrosequencing yielded a higher diversity, there was very little overlap with the cultivation approach, with only about 4 % of the OTUs recovered by cultivation found with pyrosequencing. In contrast, we also noticed that some singleton pyrosequencing OTUs where easily grown on growth media, and hence were not errors in the pyrosequencing data. This study thus showed that several factors could have a large impact on the perceived diversity, and that complementary techniques are necessary to discover the total bacterial diversity. In a second study (Chapter 3), we have examined the effects of both different bedrock types (granite and gneiss) and the presence of macrobiota (mosses, lichens and algae) on the composition of bacterial communities in high-altitude inland soils of different regions if the western S√łr Rondane Mountains (Queen Maud Land, East Antarctica), near the Belgian Princess Elisabeth research station. We have used the at present most used HTS-platform, Illumina‚Äôs MiSeq, which allows sequencing longer gene fragments and yields more sequences compared to pyrosequencing. We combined this with the ARISA genetic fingerprinting technique. We demonstrated that organic carbon was the most significant parameter in structuring bacterial communities, followed by pH, electric conductivity, bedrock type and moisture content, while spatial distance was of less importance. Diversity showed a positive correlation with moisture content. Acidobacteria and Actinobacteria dominated dry gneiss derived mineral soils, while Proteobacteria, Cyanobacteria, Armatimonadetes and candidate phylum FBP were dominant in samples with a high organic carbon content. A large part of the unexplained variation is probably caused by the absence of data about important nutrients in our dataset (nitrogen and phosphorous), together with microclimatic and topographic differences between sample locations, and noise and stochasticity. In a last study we again used the Illumina MiSeq platform to perform a pan-continental charting of benthic and littoral microbial mats. In total, 138 samples from lakes in eight Antarctic regions and two Sub-Antarctic islands were analysed. We found a significant trend of increasing biodiversity with decreasing latitude from 85¬į to 54¬į S, although this than again decreased until 45¬į S. The mean annual temperature appeared to have a highly significant effect on community structure between Sub-Antarctica and Antarctica, while, besides the geographical distance, electric conductivity, and to a lesser extent pH, was important in explaining differences between samples on the Antarctic continent. In this study, too, a very high unknown diversity was observed. Particularly Cyanobacteria and Alphaproteobacteria dominated freshwater microbial mats, while Bacteroidetes and the alphaproteobacterial Rhodobacteraceae family dominated saline lakes. The Sub-Antarctic Marion Island was highly deviant with very low species richness, dominated by Janthinobacterium (Betaproteobacteria). In conclusion this thesis supports the hypothesis that for Bacteria in the Antarctic Region, too, distinct biogeographic patterns exist and that the environment exerts large selective pressures on community structure and composition, complemented by biotic factors. There is a high amount of heterogeneity at both local and continental scale due to both spatial distance and local differences in environmental variables such as electric conductivity, pH, moisture content, organic carbon and microclimate. Although we only were able sample a fraction of the continent, it is expected that similar patterns hold across the entire continent. However, additional sampling and in depth (metagenomics) sequencing linked to extensive environmental data, combined with phylogenetic analysis is needed to resolve important questions such as within and inter-continental dispersal, functioning and correlation of observed patterns to environmental data

    More than just plants: A study of biotic stress impacts on the root microbiomes of Trifolium repens

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    New Zealand pasture plants are subject to a multitude of biotic and abiotic stresses. While the pasture plants themselves are well-studied, the microbes associated with the plants are not. In two trials, Trifolium repens (white clover), the key legume component of New Zealand pastoral agriculture, was grown in different soils from around the country exposed to several biotic treatments. We then used next generation sequencing to sequence variable regions of the ITS and 16S ribosomal DNA from the root microbiome of the white clover plants. The microbiome was partitioned in two compartments: the endosphere and rhizosphere. Multivariate analyses such as canonical correlation analysis were then used to compare the ribosomal DNA proportions to the biotic and abiotic factors challenging the plants. Data from the two trials was compared to assess robustness of the methodologies. We will present new insights into the interactions of white clover and its microbiome to biotic factors

    Processos ecol√≥gicos envolvidos na distribui√ß√£o da diversidade gen√©tica e taxon√īmica de cianobact√©rias de ecossistemas aqu√°ticos continentais

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    As cianobact√©rias s√£o microrganismos procariotos, capazes de realizar fotoss√≠ntese oxig√™nica. Ao longo de sua longa hist√≥ria evolutiva na Terra, adapta√ß√Ķes gen√©ticas, bioqu√≠micas e fisiol√≥gicas garantiram a estes procariotos a sua perpetua√ß√£o em praticamente toda a superf√≠cie terrestre. As cianobact√©rias se distribuem ao longo de habitats terrestres e aqu√°ticos, em associa√ß√£o com outros seres vivos, e mesmo em ambientes extremos. Em ecossistemas aqu√°ticos, especialmente, as cianobact√©rias s√£o encontradas em alta abund√Ęncia e s√£o as maiores respons√°veis pela produ√ß√£o prim√°ria. Al√©m disso, cianobact√©rias podem formar flora√ß√Ķes e liberar toxinas em ambientes aqu√°ticos, o que as torna intimamente relacionadas √†s condi√ß√Ķes da √°gua e √† conserva√ß√£o dos ecossistemas aqu√°ticos. Estudos sobre padr√Ķes de distribui√ß√£o de cianobact√©rias t√™m crescido na literatura e s√£o importantes uma vez que podem alertar riscos de flora√ß√£o, e tamb√©m para compreender melhor a ecologia do grupo, como habilidades de dispers√£o e prefer√™ncias de habitat. Nesse contexto, a presente tese teve como objetivo geral explorar os fatores ecol√≥gicos que influenciam a distribui√ß√£o das cianobact√©rias, com foco em ecossistemas de √°gua doce. Para isso, a tese foi estruturada em tr√™s cap√≠tulos, cada qual com o objetivo central de: (I) sintetizar, atrav√©s de uma ampla revis√£o bibliogr√°fica, padr√Ķes biogeogr√°ficos de cianobact√©rias e as evid√™ncias sobre os processos ecol√≥gicos que estruturam esses padr√Ķes; (II) reconstruir as hist√≥rias filogeogr√°ficas de duas cianobact√©rias cosmopolitas de vida livre (Raphidiopsis raciborskii e Microcystis aeruginosa), com base na diversidade gen√©tica do gene 16S rRNA, a fim de explorar se suas distribui√ß√Ķes atuais podem ser atribu√≠das aos mesmos processos ecol√≥gicos; (III) explorar os padr√Ķes de diversidade alfa e beta de cianobact√©rias planct√īnicas e perif√≠ticas (associadas √† macr√≥fita Scirpus californicus) em um sistema de lagoas subtropicais e como a influ√™ncia de vari√°veis ambientais varia entre cianobact√©rias de vida livre (planct√īnicas) e de vida associada (perif√≠ticas). Os principais achados desta tese foram: (I) tanto fatores ambientais quanto hist√≥ricos s√£o importantes na distribui√ß√£o das cianobact√©rias; no entanto, padr√Ķes de distribui√ß√£o dependem intimamente do conceito de esp√©cie, que ainda √© debatido para procariotos, incluindo cianobact√©rias, escalas espaciais e ambientais, e os vieses das metodologias aplicadas nos estudos; (II) M. aeruginosa e R. raciborskii apresentaram maior diversidade gen√©tica em latitudes tropicais e evid√™ncia de expans√£o populacional recente. No entanto, embora ambas as esp√©cies sejam consideram cosmopolitas, a filogeografia de R. raciborskii indica uma intera√ß√£o entre deriva e alguma limita√ß√£o de dispers√£o, ao passo que M. aeruginosa parece ter uma alta frequ√™ncia de dispers√£o intercontinental; (III) assembleias de cianobact√©rias planct√īnicas e perif√≠ticas s√£o distintas e estruturadas por diferentes fatores ecol√≥gicos. Enquanto a varia√ß√£o nas cianobact√©rias planct√īnicas foi determinada principalmente pelas condi√ß√Ķes da √°gua, as cianobact√©rias perif√≠ticas foram influenciadas apenas pela abund√Ęncia de outros t√°xons bacterianos. Em geral, a presente tese contribuiu para o entendimento dos fatores envolvidos na distribui√ß√£o das cianobact√©rias e como eles variam entre diferentes t√°xons, escalas espaciais e tipos de habitat. Ainda, forneceu perspectivas para investiga√ß√Ķes futuras nesse campo, a fim de contribuir para uma maior compreens√£o dos processos ecol√≥gicos que moldam a distribui√ß√£o desse importante grupo de procariotos.Cyanobacteria are prokaryotic microorganisms capable of performing oxygen photosynthesis. Throughout its long evolutionary history on Earth, genetic, biochemical and physiological adaptations have allowed to these prokaryotes to inhabit the entire terrestrial surface. Cyanobacteria are distributed throughout terrestrial and aquatic habitats, in association with organisms, and even in extreme environments. In aquatic ecosystems, especially, cyanobacteria are typically abundant and responsible for most of the primary production. In addition, cyanobacteria can form blooms and release toxins in aquatic environments, so that cyanobacteria are closely related to water conditions and conservation of aquatic ecosystems. Studies on cyanobacteria distribution patterns have increased in the literature and are important since they are able to alert the risks of cyanoblooms, and also to better understand the ecology of the group, such as dispersal abilities and habitat preferences. In this context, the present thesis aimed to explore the ecological factors that influence the distribution of cyanobacteria, focusing on freshwater ecosystems. For this, this thesis was structured in three chapters, with the main goals of: (I) to review the biogeographic patterns of cyanobacteria with focus on molecular data and the evidences from the published literature for the processes driving these patterns; (II) to reconstruct the phylogeographic histories of two free-living cosmopolitan cyanobacteria (Raphidiopsis raciborskii and Microcystis aeruginosa), based on the genetic diversity of the 16S rRNA gene, in order to explore whether their current distributions could be attributed to the same ecological processes; (III) to explore alpha and beta diversity patterns of planktonic and periphytic (associated to Scirpus californicus) cyanobacteria in a subtropical lake system, and how the influence of niche-related variables varies between free-living (planktonic) and surface-associate (periphytic) assemblages. In summary, the main findings of this thesis were that: (I) both environmental and historical factors are important in structuring cyanobacteria variation across time and space, however, distribution patterns are closely dependent on the concept of species, which is still debated for prokaryotic microorganisms, including cyanobacteria, spatial and environmental scales, and the biases of the molecular methodologies applied in the studies; (II) R. raciborskii and M. aeruginosa had greater genetic diversity in tropical latitudes and showed evidence of recent population expansion. However, although both species are considered cosmopolitan, the phylogeography of R. raciborskii indicates an interaction between drift and some dispersal limitation, whereas M. aeruginosa seems to have a high frequency of intercontinental dispersal; (III) planktonic and periphytic cyanobacteria assemblages are distinct and structured by different ecological factors. While the variation in planktonic cyanobacteria was mainly determined by water conditions, periphytic cyanobacteria were influenced only by the abundance of other bacterial taxa. In general, this thesis has contributed to the understanding of the factors involved in the distribution of cyanobacteria, and how they vary between different taxa, spatial scales and habitat types. It also provided perspectives for future research in this field, in order to contribute to a greater understanding of the ecological processes that shape the distribution of this important group of prokaryotes

    Toxic Cyanobacteria in Water

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    Estudio de los efectos biológicos de biomoléculas de origen marino sobre cultivos de células humanas y modelos animales de enfermedades humanas

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    Las crambescidinas constituyen una amplia familia de metabolitos secundarios con una interesante actividad anticancer√≠gena frente a diversos tipos de tumores de origen humano. Este trabajo caracteriza los mecanismos celulares responsables y las distintas v√≠as de se√Īalizaci√≥n implicadas. Asimismo, describe por primera vez su actividad sobre las adhesiones y el citoesqueleto celular, adem√°s de corroborar su eficacia in vivo. Las crambescinas presentan actividad citoprotectora frente al da√Īo oxidativo mediante el incremento de la expresi√≥n de las prote√≠nas de la familia de las metalotione√≠nas. La utilidad farmacol√≥gica de estos compuestos tambi√©n ha sido demostrada
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