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Protozooplankton characterization of two contrasting sites in a tropical coastal ecosystem (Guanabara Bay, RJ)
Gomes, Eli Ana Traversim;Santos, Viviane Severiano dos;Tenenbaum, Denise Rivera;Villac, Maria Célia;
Brazilian Journal of Oceanography , 2007, DOI: 10.1590/S1679-87592007000100004
Abstract: much time and resources have been invested in understanding plankton dynamics in guanabara bay (brazil), but no attention has been devoted to the protozooplankton. to fulfill this lacuna, abundance and composition of protozooplankton were investigated from january to december - 2000 in fortnightly surface water samplings at two distinct water quality sites (urca - closer to the bay entrance, more saline and cleaner waters; ramos - inner reaches, hypereutrophic waters). the density at urca (103 - 105 cell.l-1) was one to three orders of magnitude lower than at ramos (104 - 105 cell.l-1). a seasonal trend for nanoplankton and protozooplankton was more evident at urca, but both sites had lower densities during the colder period. small heterotrophic dinoflagellates (20-30 mm) were dominant in over 50% of the samples. the protozooplankton abundance and composition reflected the distinct trophic conditions states found at the bay. during the wet-warm season, non-oligotrich ciliates were representative of ramos site with gymnodiniaceae dinoflagellates, while tintinnids and heterotrophic dinoflagellates were predominantly found at urca mainly during the dry-cold season. this first descriptive study towards the understanding of the intricate relationships among the microbial food web components reveals that protozooplankton can be a good indicator of water quality conditions at the bay.
Small time scale plankton structure variations at the entrance of a tropical eutrophic bay (Guanabara Bay, Brazil)  [cached]
Mariana Guenther,Isabel Lima,Glenda Mugrabe,Denise Rivera Tenenbaum
Brazilian Journal of Oceanography , 2012,
Abstract: The dynamics of the plankton compartments at the entrance of Guanabara Bay (SE Brazil) were assessed during a short-term temporal survey to estimate their trophic correlations. Size-fractioned phytoplankton (picoplankton: < 2μm, nanoplankton: 2-20μm and microplankton: > 20μm) biomass and photosynthetic efficiency, composition and abundance of the auto-and heterotrophic nano-and microplankton, and mesozooplankton were evaluated at a fixed station for 3 consecutive days at 3-h intervals, in the surface and bottom (20m) layers. The variability of almost all plankton compartments in the surface layer was directly dependent on temperature, indicating the great influence of the circulation at the entrance of the bay on plankton structure. In the surface layer, the mesozooplankton seems to be sustained by both autotrophic nano-and picoplankton, this last being channeled through the microzooplankton. Near the bottom, both auto-and heterotrophic microplankton are probably supporting the mesozooplankton biomass. Our findings thus suggest that the entrance of Guanabara bay presents a multivorous food web, i.e., a combination of both grazing and microbial trophic pathways. A dinamica dos vários compartimentos do plancton foi avaliada durante uma série de curta dura o na entrada da baía de Guanabara (SE do Brasil), com o objetivo de estimar suas correla es tróficas. A biomassa e eficiência fotossíntética das três fra es do fitoplancton (picoplancton: < 2μm, nanoplancton: 2-20μm e microplancton: > 20μm), juntamente com a composi o e abundancia do nano-e microplancton auto-e heterótrofos e do mesozooplancton, foram determinadas em uma esta o fixa durante 3 dias consecutivos, a intervalos de 3h, nas camadas de superfície e de fundo (20m). A variabilidade de quase todos os compartimentos do plancton na superfície foi diretamente relacionada à temperatura, indicando forte influência da circula o da entrada da baía na estrutura planct nica. Na camada superficial, o mesozooplancton parece ser alimentado pelo nano-e picoplancton autótrofos, esse último sendo sustentado pelo microzooplancton. Próximo ao fundo, o microplancton auto-e heterótrofo est o possivelmente sustentando a biomassa mesozooplanct nica. Nossos resultados sugerem, portanto, que na entrada da baía de Guanabara esteja estabelecida uma rede trófica multívora, i.e., uma combina o entre as cadeias microbiana e de pastagem.
Biomass distribution of heterotrophic and autotrophic microorganisms of the photic layer in Cuban southern oceanic waters
Lugioyo,Gladys Margarita; Loza,Sandra; Abreu,Paulo C;
Revista de Biología Tropical , 2007,
Abstract: we measured the vertical and seasonal distribution of picoplankton (0.2-2 μm) and nanoplankton (2-20 μm) in the photic layer of cuban southern oceanic and coastal waters. the concentration of the different fractions was estimated by epifluorescence microscopy. heterotrophic components from the different fractions showed higher vertical stratification in the oceanic station in comparison to the coastal one. the autotrophic components showed an irregular vertical distribution pattern, both in coastal and oceanic stations. in all the analyzed stations, the heterotrophic bacteria showed an inverse correlation with the autotrophic (r= -0.98), and the heterotrophic nanoplankton (r= -0.96). auto and heterotrophic nanoplankton probably regulate bacteria abundance by predation, although autotrophic nanoplankton may represent a source of organic matter for microorganisms. rev. biol. trop. 55 (2): 449-457. epub 2007 june, 29.
Filamentous Biopolymers on Surfaces: Atomic Force Microscopy Images Compared with Brownian Dynamics Simulation of Filament Deposition  [PDF]
Norbert Mücke,Konstantin Klenin,Robert Kirmse,Malte Bussiek,Harald Herrmann,Mathias Hafner,J?rg Langowski
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0007756
Abstract: Nanomechanical properties of filamentous biopolymers, such as the persistence length, may be determined from two-dimensional images of molecules immobilized on surfaces. For a single filament in solution, two principal adsorption scenarios are possible. Both scenarios depend primarly on the interaction strength between the filament and the support: i) For interactions in the range of the thermal energy, the filament can freely equilibrate on the surface during adsorption; ii) For interactions much stronger than the thermal energy, the filament will be captured by the surface without having equilibrated. Such a ‘trapping’ mechanism leads to more condensed filament images and hence to a smaller value for the apparent persistence length. To understand the capture mechanism in more detail we have performed Brownian dynamics simulations of relatively short filaments by taking the two extreme scenarios into account. We then compared these ‘ideal’ adsorption scenarios with observed images of immobilized vimentin intermediate filaments on different surfaces. We found a good agreement between the contours of the deposited vimentin filaments on mica (‘ideal’ trapping) and on glass (‘ideal’ equilibrated) with our simulations. Based on these data, we have developed a strategy to reliably extract the persistence length of short worm-like chain fragments or network forming filaments with unknown polymer-surface interactions.
Bacteriological study of the superficial sediments of Guanabara bay, RJ, Brazil
Sobrinho da Silva, Frederico;Pereira, Daniella da Costa;Nu?ez, Leonisa Sanchez;Krepsk, Natascha;Fontana, Luiz Francisco;Baptista Neto, José Ant?nio;Crapez, Mirian Araújo Carlos;
Brazilian Journal of Oceanography , 2008, DOI: 10.1590/S1679-87592008000100002
Abstract: thirty sediment samples were collected in guanabara bay in august, november and december 2005. the material was analyzed for organic matter, total and faecal coliforms, heterotrophic bacteria, bacterial respiratory activity, esterase activity and electron transport system activity. the organic matter in the superficial sediments (2 cm) ranged from 4 to 6%. the highest level of total coliforms and faecal coliforms were 1.7 x 105 mpn/g and 1.1 x 103 mpn/g, respectively. heterotrophic bacteria presented the highest values at station 7 (4.1 x 106 cfu/g) and the lowest values at station 3 (7 x 104 cfu/g) (northwestern part of guanabara bay). esterase enzyme activity showed activity in the sediment of all 30 stations. electron transport system activity ranged between 0.047 ml o2/h/g and 0.366 ml o2/h/g at six stations. the benthic microbial foodweb is anaerobic. anaerobic processes such as fermentation, denitrification and sulphate-reduction are responsible for the biogeochemical cycles in the sediment of guanabara bay. the input of untreated sewage in the mangue channel outflow in guanabara bay has favored the increase of the organic load, and the maintenance of the total coliforms and faecal coliforms in the sediment. faecal coliforms have been reported to be a good indicator of aquatic pollution and organic contamination in the water column, but total coliforms may be an ideal candidate group for sediment quality tests as well.
Biomass distribution of heterotrophic and autotrophic microorganisms of the photic layer in Cuban southern oceanic waters
Gladys Margarita Lugioyo,Sandra Loza,Paulo C Abreu
Revista de Biología Tropical , 2007,
Abstract: We measured the vertical and seasonal distribution of picoplankton (0.2-2 μm) and nanoplankton (2-20 μm) in the photic layer of Cuban southern oceanic and coastal waters. The concentration of the different fractions was estimated by epifluorescence microscopy. Heterotrophic components from the different fractions showed higher vertical stratification in the oceanic station in comparison to the coastal one. The autotrophic components showed an irregular vertical distribution pattern, both in coastal and oceanic stations. In all the analyzed stations, the heterotrophic bacteria showed an inverse correlation with the autotrophic (r= -0.98), and the heterotrophic nanoplankton (r= -0.96). Auto and heterotrophic nanoplankton probably regulate bacteria abundance by predation, although autotrophic nanoplankton may represent a source of organic matter for microorganisms. Rev. Biol. Trop. 55 (2): 449-457. Epub 2007 June, 29. Determinamos la distribución vertical y estacional del picoplancton (0.2-2 μm) y el nanoplancton (2-20 μm) en la capa fótica de las aguas oceánicas y costeras al sur de Cuba. La concentración de las diferentes fracciones fue estimada mediante microscopía de epifluorescencia. Los componentes heterotróficos de las diferentes fracciones mostraron una elevada estratificación vertical en la estación oceánica en comparación con la estación costera. Por otro lado, los componentes autotróficos presentaron un patrón de distribución vertical irregular tanto en la estación costera como en la oceánica. En los análisis realizados las bacterias heterótrofas mostraron una correlación inversa con el nanoplancton autótrofo (r= -0.98), y con el nanoplancton heterótrofo (r= -0.96). Estos resultados sugieren que el nanoplancton (autótrofo y heterótrofo) probablemente regula la abundancia de bacterias mediante la depredación, además que el nanoplancton autótrofo pudiera representar una fuente de materia orgánica para los microorganismos.
Succession in rocky intertidal benthic communities in areas with different pollution levels at Guanabara Bay (RJ-Brazil)
Breves-Ramos, André;Lavrado, Helena Passeri;Junqueira, Andrea de Oliveira Ribeiro;Silva, Sérgio Henrique Gon?alves da;
Brazilian Archives of Biology and Technology , 2005, DOI: 10.1590/S1516-89132005000800012
Abstract: the aim of this study was to describe and compare the succession of intertidal benthic communities in two areas at guanabara bay, rj, brazil: urca, an area submitted to moderated organic pollution and catal?o, an extremely polluted area. three transects in each area were scraped one month before the beginning of this study in order to evaluate the recruitment (recruitment-treatments). three other transects were monitored without manipulation (monitoring treatments). species composition and relative abundance were evaluated monthly between september and december, 2000. a total of 26 species was found at urca and 13 at catal?o. the percent cover of the most abundant organisms was not similar between treatments at urca after four months, while in catal?o, the similarity was 72% in the second month. the faster community development and recovery at the most polluted area was probably related to the existence of simple and resilient communities in more impacted areas.
Antagonistic interactions between filamentous heterotrophs and the cyanobacterium Nostoc muscorum
Miroslav Svercel, Bianca Saladin, Sofia J van Moorsel, Sarah Wolf, Homayoun C Bagheri
BMC Research Notes , 2011, DOI: 10.1186/1756-0500-4-357
Abstract: F. aestuarina BUZ 2 significantly reduced the cyanobacterial population whereas F. limi BUZ 3 did not. Physical contact between heterotrophs and autotroph was observed and the cyanobacterial cells showed some level of damage and lysis. Therefore, either contact lysis or entrapment with production of extracellular compounds in close vicinity of host cells could be considered as potential modes of action.The supernatants from pure heterotrophic cultures did not have an effect on Nostoc cultures. However, supernatant from mixed cultures of BUZ 2 and Nostoc had a negative effect on cyanobacterial growth, indicating that the lytic compounds were only produced in the presence of Nostoc.The growth and survival of tested heterotrophs was enhanced by the presence of Nostoc or its metabolites, suggesting that the heterotrophs could utilize the autotrophs and its products as a nutrient source. However, the autotroph could withstand and out-compete the heterotrophs under nutrient poor conditions.Our results suggest that the nutrients in cultivation media, which boost or reduce the number of heterotrophs, were the important factor influencing the outcome of the interplay between filamentous heterotrophs and autotrophs. For better understanding of these interactions, additional research is needed. In particular, it is necessary to elucidate the mode of action for lysis by heterotrophs, and the possible defense mechanisms of the autotrophs.Cyanobacteria are photoautotrophic bacteria obtaining their carbon and energy by photosynthesis, while heterotrophic bacteria rely on organic compounds as their carbon and energy source. Within their natural aquatic environment, autotrophic cyanobacteria and heterotrophic bacteria live in a close relationship and can interact in various ways (synergistic, neutral, antagonistic). At present, little is known about such interactions, especially between filamentous cyanobacteria and filamentous heterotrophs. Few studies touching those relationships
Zoneamento Ambiental da Baía de Guanabara  [PDF]
Claudio Ant?nio G. Egler,Carla Bernadete Madureira Cruz,Paulo Frederico Hald Madsen,Samir de Menezes Costa
Anuário do Instituto de Geociências , 2003,
Abstract: The paper presents a proposition for the Guanabara Bay Environmental Zoning , which aims to contribute for its sustainable management. The methodology was developed in three analytical scales: a strategical conception of human settlement, a logistic vision of fluviomarine dynamics and a tactic proposition of institutional intervention.
Filamentous growth in Saccharomyces cerevisiae
Ceccato-Antonini, Sandra Regina;Sudbery, Peter Edwin;
Brazilian Journal of Microbiology , 2004, DOI: 10.1590/S1517-83822004000200001
Abstract: fungal dimorphism is a complex phenomenon triggered by a large variety of environmental factors and consists of a reversible alternating pattern of growth between different elliptical and filamentous forms of cells. understanding the mechanisms that regulate these events is of major interest because of their implications in fungal pathogenesis, cell differentiation and industry. diploid cells of saccharomyces cerevisiae transform from budding yeast to pseudohyphae when starved for nitrogen, giving the cells an advantage in food foraging, which is sensed by at least two signal transduction pathways: the map kinase (mapk) and the pka (camp-dependent protein kinase a) pathways. the output of these signalling pathways is the expression of pseudohypha-specific genes, whose expression profiles change and is accompanied by a g2 delay in the cell cycle and a prolonged period of polarized growth. haploid yeast strains show a similar growth type after prolonged incubation on rich medium plates. the cells form chains and invade the agar on the edge of the colony, but they do not become elongated. this growth type is referred to as haploid invasive growth. alcohols can also induce filamentous growth in s. cerevisiae, promoting aberrant and elongated morphology. the three forms of filamentous growth are revised in this article and also the pathways involved in sensing, signaling and signal transduction during filamentous growth.
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