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Sample records for bloom intracellular bacteria

  1. Functional genomics of intracellular bacteria.

    Science.gov (United States)

    de Barsy, Marie; Greub, Gilbert

    2013-07-01

    During the genomic era, a large amount of whole-genome sequences accumulated, which identified many hypothetical proteins of unknown function. Rapidly, functional genomics, which is the research domain that assign a function to a given gene product, has thus been developed. Functional genomics of intracellular pathogenic bacteria exhibit specific peculiarities due to the fastidious growth of most of these intracellular micro-organisms, due to the close interaction with the host cell, due to the risk of contamination of experiments with host cell proteins and, for some strict intracellular bacteria such as Chlamydia, due to the absence of simple genetic system to manipulate the bacterial genome. To identify virulence factors of intracellular pathogenic bacteria, functional genomics often rely on bioinformatic analyses compared with model organisms such as Escherichia coli and Bacillus subtilis. The use of heterologous expression is another common approach. Given the intracellular lifestyle and the many effectors that are used by the intracellular bacteria to corrupt host cell functions, functional genomics is also often targeting the identification of new effectors such as those of the T4SS of Brucella and Legionella.

  2. Intracellular bacteria: the origin of dinoflagellate toxicity.

    Science.gov (United States)

    Silva, E S

    1990-01-01

    Dinoflagellate blooms of the same species have been registered either as toxic or nontoxic and, in the latter case, toxicity may be of different types. A hypothesis has been formulated according to which the bacteria having in some way taken part in the toxin formation are either inside the dinoflagellate cell or in the nutritive liquid. The presence of intracellular bacteria in those microorganisms has been studied mainly in material from cultures, a few from the sea, and several strains were isolated from different species. Experiments with crossed inoculations have shown that the bacterial strain from Gonyaulax tamarensis caused the cells of some other species to become toxic. From nontoxic clonal cultures of Prorocentrum balticum, Glenodinium foliaceum, and Gyrodinium instriatum, after inoculation of that bacterial strain, cultures were obtained whose cell extracts showed the same kind of toxicity as G. tamarensis. No toxic action could be found in the extracts of the bacterial cells form the assayed strains. The interference of intracellular bacteria in the metabolism of dinoflagellates must be the main cause of their toxicity.

  3. Macrophage defense mechanisms against intracellular bacteria.

    Science.gov (United States)

    Weiss, Günter; Schaible, Ulrich E

    2015-03-01

    Macrophages and neutrophils play a decisive role in host responses to intracellular bacteria including the agent of tuberculosis (TB), Mycobacterium tuberculosis as they represent the forefront of innate immune defense against bacterial invaders. At the same time, these phagocytes are also primary targets of intracellular bacteria to be abused as host cells. Their efficacy to contain and eliminate intracellular M. tuberculosis decides whether a patient initially becomes infected or not. However, when the infection becomes chronic or even latent (as in the case of TB) despite development of specific immune activation, phagocytes have also important effector functions. Macrophages have evolved a myriad of defense strategies to combat infection with intracellular bacteria such as M. tuberculosis. These include induction of toxic anti-microbial effectors such as nitric oxide and reactive oxygen intermediates, the stimulation of microbe intoxication mechanisms via acidification or metal accumulation in the phagolysosome, the restriction of the microbe's access to essential nutrients such as iron, fatty acids, or amino acids, the production of anti-microbial peptides and cytokines, along with induction of autophagy and efferocytosis to eliminate the pathogen. On the other hand, M. tuberculosis, as a prime example of a well-adapted facultative intracellular bacterium, has learned during evolution to counter-balance the host's immune defense strategies to secure survival or multiplication within this otherwise hostile environment. This review provides an overview of innate immune defense of macrophages directed against intracellular bacteria with a focus on M. tuberculosis. Gaining more insights and knowledge into this complex network of host-pathogen interaction will identify novel target sites of intervention to successfully clear infection at a time of rapidly emerging multi-resistance of M. tuberculosis against conventional antibiotics. © 2015 The Authors

  4. Macrophage defense mechanisms against intracellular bacteria

    Science.gov (United States)

    Weiss, Günter; Schaible, Ulrich E

    2015-01-01

    Macrophages and neutrophils play a decisive role in host responses to intracellular bacteria including the agent of tuberculosis (TB), Mycobacterium tuberculosis as they represent the forefront of innate immune defense against bacterial invaders. At the same time, these phagocytes are also primary targets of intracellular bacteria to be abused as host cells. Their efficacy to contain and eliminate intracellular M. tuberculosis decides whether a patient initially becomes infected or not. However, when the infection becomes chronic or even latent (as in the case of TB) despite development of specific immune activation, phagocytes have also important effector functions. Macrophages have evolved a myriad of defense strategies to combat infection with intracellular bacteria such as M. tuberculosis. These include induction of toxic anti-microbial effectors such as nitric oxide and reactive oxygen intermediates, the stimulation of microbe intoxication mechanisms via acidification or metal accumulation in the phagolysosome, the restriction of the microbe's access to essential nutrients such as iron, fatty acids, or amino acids, the production of anti-microbial peptides and cytokines, along with induction of autophagy and efferocytosis to eliminate the pathogen. On the other hand, M. tuberculosis, as a prime example of a well-adapted facultative intracellular bacterium, has learned during evolution to counter-balance the host's immune defense strategies to secure survival or multiplication within this otherwise hostile environment. This review provides an overview of innate immune defense of macrophages directed against intracellular bacteria with a focus on M. tuberculosis. Gaining more insights and knowledge into this complex network of host-pathogen interaction will identify novel target sites of intervention to successfully clear infection at a time of rapidly emerging multi-resistance of M. tuberculosis against conventional antibiotics. PMID:25703560

  5. Physics of Intracellular Organization in Bacteria.

    Science.gov (United States)

    Wingreen, Ned S; Huang, Kerwyn Casey

    2015-01-01

    With the realization that bacteria achieve exquisite levels of spatiotemporal organization has come the challenge of discovering the underlying mechanisms. In this review, we describe three classes of such mechanisms, each of which has physical origins: the use of landmarks, the creation of higher-order structures that enable geometric sensing, and the emergence of length scales from systems of chemical reactions coupled to diffusion. We then examine the diversity of geometric cues that exist even in cells with relatively simple geometries, and end by discussing both new technologies that could drive further discovery and the implications of our current knowledge for the behavior, fitness, and evolution of bacteria. The organizational strategies described here are employed in a wide variety of systems and in species across all kingdoms of life; in many ways they provide a general blueprint for organizing the building blocks of life.

  6. Intracellular chemical gradients: morphing principle in bacteria

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    Endres Robert G

    2012-09-01

    Full Text Available Abstract Advances in computational biology allow systematic investigations to ascertain whether internal chemical gradients can be maintained in bacteria – an open question at the resolution limit of fluorescence microscopy. While it was previously believed that the small bacterial cell size and fast diffusion in the cytoplasm effectively remove any such gradient, a new computational study published in BMC Biophysics supports the emerging view that gradients can exist. The study arose from the recent observation that phosphorylated CtrA forms a gradient prior to cell division in Caulobacter crescentus, a bacterium known for its complicated cell cycle. Tropini et al. (2012 postulate that such gradients can provide an internal chemical compass, directing protein localization, cell division and cell development. More specifically, they describe biochemical and physical constraints on the formation of such gradients and explore a number of existing bacterial cell morphologies. These chemical gradients may limit in vitro analyses, and may ensure timing control and robustness to fluctuations during critical stages in cell development.

  7. Potent Antibacterial Nanoparticles against Biofilm and Intracellular Bacteria

    Science.gov (United States)

    Mu, Haibo; Tang, Jiangjiang; Liu, Qianjin; Sun, Chunli; Wang, Tingting; Duan, Jinyou

    2016-01-01

    The chronic infections related to biofilm and intracellular bacteria are always hard to be cured because of their inherent resistance to both antimicrobial agents and host defenses. Herein we develop a facile approach to overcome the above conundrum through phosphatidylcholine-decorated Au nanoparticles loaded with gentamicin (GPA NPs). The nanoparticles were characterized by scanning electron microscopy (SEM), dynamic light scattering (DLS) and ultraviolet-visible (UV-vis) absorption spectra which demonstrated that GPA NPs with a diameter of approximately 180 nm were uniform. The loading manner and release behaviors were also investigated. The generated GPA NPs maintained their antibiotic activities against planktonic bacteria, but more effective to damage established biofilms and inhibited biofilm formation of pathogens including Gram-positive and Gram-negative bacteria. In addition, GPA NPs were observed to be nontoxic to RAW 264.7 cells and readily engulfed by the macrophages, which facilitated the killing of intracellular bacteria in infected macrophages. These results suggested GPA NPs might be a promising antibacterial agent for effective treatment of chronic infections due to microbial biofilm and intracellular bacteria.

  8. Chitosan conjugation enables intracellular bacteria susceptible to aminoglycoside antibiotic.

    Science.gov (United States)

    Mu, Haibo; Niu, Hong; Wang, Dongdong; Sun, Feifei; Sun, Yuelin; Duan, Jinyou

    2016-11-01

    Most chronic infections are difficult to eradicate because bacteria capable of surviving in host-infected cells may be protected from the killing actions of antibiotics, leading to therapy failures and disease relapses. Here we demonstrated that covalent-coupling chitosan to streptomycin significantly improved intracellular bactericidal capacity towards multiple organisms within phagocytic or nonphagocytic cells. Structure-activity relationship investigations indicated that antibiotic contents, molecular size and positive charges of the conjugate were the key to retain this intracellular bactericidal activity. Mechanistic insight demonstrated the conjugate was capable to target and eliminate endocytic or endosomal escaped bacteria through facilitating the direct contact between the antibiotic and intracellular organism. In vivo acute infection models indicated that compared to equal dose of the antibiotic, chitosan-streptomycin (C-S) conjugate and especially the human serum album binding chitosan-streptomycin conjugate (HCS) complex formed by human serum album and C-S conjugate greatly decreased the bacteria burden in the spleen and liver in both wild type and immuno-suppressive mice. Furthermore, the HCS complex remarkably reduced mortality of infected TLR2 deficient mice, mimicking immune-compromised persons who were more susceptible to bacterial infections. These findings might open up a new avenue to combat intracellular bacterial infection by aminoglycosides antibiotics at a lower effective dose. © The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  9. Potent Antibacterial Nanoparticles against Biofilm and Intracellular Bacteria

    OpenAIRE

    Mu, Haibo; Tang, Jiangjiang; Liu, Qianjin; Sun, Chunli; Wang, Tingting; Duan, Jinyou

    2016-01-01

    The chronic infections related to biofilm and intracellular bacteria are always hard to be cured because of their inherent resistance to both antimicrobial agents and host defenses. Herein we develop a facile approach to overcome the above conundrum through phosphatidylcholine-decorated Au nanoparticles loaded with gentamicin (GPA NPs). The nanoparticles were characterized by scanning electron microscopy (SEM), dynamic light scattering (DLS) and ultraviolet?visible (UV?vis) absorption spectra...

  10. Retrieved bacteria from Noctiluca miliaris (green) bloom of the northeastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Basu, S.; Matondkar, S.G.P.; Furtado, I.

    Chinese Journal of Oceanology and Limnology Vol. 31 No. 1, P. 10-20, 2013 http://dx.doi.org/ : 10.1007/s00343-013-2017-2 Retreived bacteria from Noctiluca m iliaris (green) bloom of the northeastern Arabian Sea BASU Subhajit 1 , MATONDKAR SG Prabhu... in principle Mar. 13, 2012; accepted for publication May 22, 2012 © Chinese Society for Oceanology and Limnology, Science Press, and Springer-Verlag Berlin Heidelberg 2013 Abstract In recent years, seasonal blooms of the dinofl agellate Noctiluca...

  11. Spatio-temporal interdependence of bacteria and phytoplankton during a Baltic Sea spring bloom

    Directory of Open Access Journals (Sweden)

    Carina eBunse

    2016-04-01

    Full Text Available In temperate systems, phytoplankton spring blooms deplete inorganic nutrients and are major sources of organic matter for the microbial loop. In response to phytoplankton exudates and environmental factors, heterotrophic microbial communities are highly dynamic and change their abundance and composition both on spatial and temporal scales. Yet, most of our understanding about these processes comes from laboratory model organism studies, mesocosm experiments or single temporal transects. Spatial-temporal studies examining interactions of phytoplankton blooms and bacterioplankton community composition and function, though being highly informative, are scarce. In this study, pelagic microbial community dynamics (bacteria and phytoplankton and environmental variables were monitored during a spring bloom across the Baltic Proper (two cruises between North Germany to Gulf of Finland. To test to what extent bacterioplankton community composition relates to the spring bloom, we used next generation amplicon sequencing of the 16S rRNA gene, phytoplankton diversity analysis based on microscopy counts and population genotyping of the dominating diatom Skeletonema marinoi. Several phytoplankton bloom related and environmental variables were identified to influence bacterial community composition. Members of Bacteroidetes and Alphaproteobacteria dominated the bacterial community composition but the bacterial groups showed no apparent correlation with direct bloom related variables. The less abundant bacterial phyla Actinobacteria, Planctomycetes, and Verrucomicrobia, on the other hand, were strongly associated with phytoplankton biomass, diatom:dinoflagellate ratio and colored dissolved organic matter (cDOM. Many bacterial operational taxonomic units (OTUs showed high niche specificities. For example, particular Bacteroidetes OTUs were associated with two distinct genetic clusters of S. marinoi. Our study revealed the complexity of interactions of bacterial

  12. Retreived bacteria from Noctiluca miliaris (green) bloom of the northeastern Arabian Sea

    Science.gov (United States)

    Basu, Subhajit; Matondkar, S. G. Prabhu; Furtado, Irene

    2013-01-01

    In recent years, seasonal blooms of the dinoflagellate Noctiluca miliaris have appeared in the open-waters of the northern Arabian Sea (NAS). This study provides the first characterization of bacteria from a seasonal bloom of green Noctiluca of NAS (20°N-17°N and 64°E-70°E), during the spring-inter-monsoon cruise of Sagar Sampada 253, in March 2007. Bacterial growth as assessed by most-probable number (MPN) and plate counts, revealed `variable-physiotypes' over a wide range of salinities (0%-25% w/v NaCl), pH levels (5-8.5), and organic nutrient strengths, in comparison to non-bloom waters. MPN indices of bacteria in surface waters of bloom stations *DWK and *PRB, corresponded to (3.08-4.41)×103 cells/mL at 3.5% NaCl (w/v), and (2.82-9.49)×102 cells/mL at 25% (w/v) NaCl in tryptone-yeast extract broth (TYE). Plate counts were (1.12-4)×106 CFU/mL at 0% (w/v) NaCl, (1.28-3.9)×106 CFU/mL at 3.5% (w/v) NaCl, and (0.4-7)×104 CFU/mL at 25% NaCl (w/v) on TYE. One-tenth-strength Zobell's gave (0.6-3.74)×105 CFU/mL at pH 5 to (3.58-7.5)×105 CFU/mL at pH 8.5. These bacteria were identified to the genera Bacillus, Cellulomonas, Staphylococcus, Planococcus, Dietzia, Virgibacillus, Micrococcus, Sporosarcinae, Leucobacter, and Halomonas. The identity of three strains (GUFBSS253N2, GUFBSS253N30, and GUFBSS253N84) was confirmed through 16S rDNA sequence homology as Bacillus cohnii, Bacillus flexus, and Bacillus cereus. The ˜2-3-fold higher plate counts of culturable bacteria from the open-waters of the NAS indicate that these bacteria could critically determine the biogeochemical dynamics of the bloom and its milieu. The role of these bacteria in sustaining/terminating the bloom is under evaluation.

  13. Subversion of the cytoskeleton by intracellular bacteria: lessons from Listeria, Salmonella, and Vibrio

    Science.gov (United States)

    de Souza Santos, Marcela; Orth, Kim

    2018-01-01

    Summary Entry into host cells and intracellular persistence by invasive bacteria are tightly coupled to the ability of the bacterium to disrupt the eukaryotic cytoskeletal machinery. Herein we review the main strategies used by three intracellular pathogens to harness key modulators of the cytoskeleton. Two of these bacteria, namely Listeria monocytogenes and Salmonella enterica serovar Typhimurium, exhibit quite distinct intracellular lifestyles, and therefore, provide a comprehensive panel for the understanding of the intricate bacteria-cytoskeleton interplay during infections. The emerging intracellular pathogen Vibrio parahaemolyticus is depicted as a developing model for the uncovering of novel mechanisms used to hijack the cytoskeleton. PMID:25440316

  14. Bloom of resident antibiotic-resistant bacteria in soil following manure fertilization.

    Science.gov (United States)

    Udikovic-Kolic, Nikolina; Wichmann, Fabienne; Broderick, Nichole A; Handelsman, Jo

    2014-10-21

    The increasing prevalence of antibiotic-resistant bacteria is a global threat to public health. Agricultural use of antibiotics is believed to contribute to the spread of antibiotic resistance, but the mechanisms by which many agricultural practices influence resistance remain obscure. Although manure from dairy farms is a common soil amendment in crop production, its impact on the soil microbiome and resistome is not known. To gain insight into this impact, we cultured bacteria from soil before and at 10 time points after application of manure from cows that had not received antibiotic treatment. Soil treated with manure contained a higher abundance of β-lactam-resistant bacteria than soil treated with inorganic fertilizer. Functional metagenomics identified β-lactam-resistance genes in treated and untreated soil, and indicated that the higher frequency of resistant bacteria in manure-amended soil was attributable to enrichment of resident soil bacteria that harbor β-lactamases. Quantitative PCR indicated that manure treatment enriched the blaCEP-04 gene, which is highly similar (96%) to a gene found previously in a Pseudomonas sp. Analysis of 16S rRNA genes indicated that the abundance of Pseudomonas spp. increased in manure-amended soil. Populations of other soil bacteria that commonly harbor β-lactamases, including Janthinobacterium sp. and Psychrobacter pulmonis, also increased in response to manure treatment. These results indicate that manure amendment induced a bloom of certain antibiotic-resistant bacteria in soil that was independent of antibiotic exposure of the cows from which the manure was derived. Our data illustrate the unintended consequences that can result from agricultural practices, and demonstrate the need for empirical analysis of the agroecosystem.

  15. Coupling of heterotrophic bacteria to phytoplankton bloom development at different pCO2 levels: a mesocosm study

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    R. Thyrhaug

    2008-07-01

    Full Text Available The predicted rise in anthropogenic CO2 emissions will increase CO2 concentrations and decrease seawater pH in the upper ocean. Recent studies have revealed effects of pCO2 induced changes in seawater chemistry on a variety of marine life forms, in particular calcifying organisms. To test whether the predicted increase in pCO2 will directly or indirectly (via changes in phytoplankton dynamics affect abundance, activities, and community composition of heterotrophic bacteria during phytoplankton bloom development, we have aerated mesocosms with CO2 to obtain triplicates with three different partial pressures of CO2 (pCO2: 350 μatm (1×CO2, 700 μatm (2×CO2 and 1050 μatm (3×CO2. The development of a phytoplankton bloom was initiated by the addition of nitrate and phosphate. In accordance to an elevated carbon to nitrogen drawdown at increasing pCO2, bacterial production (BPP of free-living and attached bacteria as well as cell-specific BPP (csBPP of attached bacteria were related to the C:N ratio of suspended matter. These relationships significantly differed among treatments. However, bacterial abundance and activities were not statistically different among treatments. Solely community structure of free-living bacteria changed with pCO2 whereas that of attached bacteria seemed to be independent of pCO2 but tightly coupled to phytoplankton bloom development. Our findings imply that changes in pCO2, although reflected by changes in community structure of free-living bacteria, do not directly affect bacterial activity. Furthermore, bacterial activity and dynamics of heterotrophic bacteria, especially of attached bacteria, were tightly correlated to phytoplankton development and, hence, may also potentially depend on changes in pCO2.

  16. Pronounced daily succession of phytoplankton, archaea and bacteria following a spring bloom.

    Science.gov (United States)

    Needham, David M; Fuhrman, Jed A

    2016-02-29

    Marine phytoplankton perform approximately half of global carbon fixation, with their blooms contributing disproportionately to carbon sequestration(1), and most phytoplankton production is ultimately consumed by heterotrophic prokaryotes(2). Therefore, phytoplankton and heterotrophic community dynamics are important in modelling carbon cycling and the impacts of global change(3). In a typical bloom, diatoms dominate initially, transitioning over several weeks to smaller and motile phytoplankton(4). Here, we show unexpected, rapid community variation from daily rRNA analysis of phytoplankton and prokaryotic community members following a bloom off southern California. Analysis of phytoplankton chloroplast 16S rRNA demonstrated ten different dominant phytoplankton over 18 days alone, including four taxa with animal toxin-producing strains. The dominant diatoms, flagellates and picophytoplankton varied dramatically in carbon export potential. Dominant prokaryotes also varied rapidly. Euryarchaea briefly became the most abundant organism, peaking over a few days to account for about 40% of prokaryotes. Phytoplankton and prokaryotic communities correlated better with each other than with environmental parameters. Extending beyond the traditional view of blooms being controlled primarily by physics and inorganic nutrients, these dynamics imply highly heterogeneous, continually changing conditions over time and/or space and suggest that interactions among microorganisms are critical in controlling plankton diversity, dynamics and fates.

  17. Inhibitory activity of the isoflavone biochanin a on intracellular bacteria of genus Chlamydia and initial development of a buccal formulation

    DEFF Research Database (Denmark)

    Hanski, Leena; Genina, Natalja; Uvell, Hanna

    2014-01-01

    Given the established role of Chlamydia spp. as causative agents of both acute and chronic diseases, search for new antimicrobial agents against these intracellular bacteria is required to promote human health. Isoflavones are naturally occurring phytoestrogens, antioxidants and efflux pump...

  18. Intracellular vesicles as reproduction elements in cell wall-deficient L-form bacteria.

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    Yves Briers

    Full Text Available Cell wall-deficient bacteria, or L-forms, represent an extreme example of bacterial plasticity. Stable L-forms can multiply and propagate indefinitely in the absence of a cell wall. Data presented here are consistent with the model that intracellular vesicles in Listeria monocytogenes L-form cells represent the actual viable reproductive elements. First, small intracellular vesicles are formed along the mother cell cytoplasmic membrane, originating from local phospholipid accumulation. During growth, daughter vesicles incorporate a small volume of the cellular cytoplasm, and accumulate within volume-expanding mother cells. Confocal Raman microspectroscopy demonstrated the presence of nucleic acids and proteins in all intracellular vesicles, but only a fraction of which reveals metabolic activity. Following collapse of the mother cell and release of the daughter vesicles, they can establish their own membrane potential required for respiratory and metabolic processes. Premature depolarization of the surrounding membrane promotes activation of daughter cell metabolism prior to release. Based on genome resequencing of L-forms and comparison to the parental strain, we found no evidence for predisposing mutations that might be required for L-form transition. Further investigations revealed that propagation by intracellular budding not only occurs in Listeria species, but also in L-form cells generated from different Enterococcus species. From a more general viewpoint, this type of multiplication mechanism seems reminiscent of the physicochemical self-reproducing properties of abiotic lipid vesicles used to study the primordial reproduction pathways of putative prokaryotic precursor cells.

  19. Fastidious intracellular bacteria as causal agents of community-acquired pneumonia.

    Science.gov (United States)

    Lamoth, Frédéric; Greub, Gilbert

    2010-07-01

    Intracellular bacteria are common causes of community-acquired pneumonia that grow poorly or not at all on standard culture media and do not respond to beta-lactam antibiotic therapy. Apart from well-established agents of pneumonia such as Legionella pneumophila, Mycoplasma pneumoniae, Chlamydia pneumoniae, Chlamydia psittaci and Coxiella burnetii, some new emerging pathogens have recently been recognized, mainly Parachlamydia acanthamoebae and Simkania negevensis, two Chlamydia-related bacteria. Most of them are causes of benign and self-limited infections. However, they may cause severe pneumonia in some cases (i.e., Legionnaires' disease) and they may cause outbreaks representing a public health problem deserving prompt recognition and appropriate therapy. Although extrapulmonary manifestations are often present, no clinical features allow them to be distinguished from classical bacterial agents of pneumonia such as Streptococcus pneumoniae. Thus, specific molecular diagnostic tools are very helpful for early recognition of the offending bacteria, whereas serology often only allows retrospective or late diagnosis. Macrolides remain the best empirical treatment of intracellular respiratory pathogens, although some observational studies suggest that quinolones may be superior for the treatment of legionellosis.

  20. Flow cytometry as an improved method for the titration of Chlamydiaceae and other intracellular bacteria.

    Science.gov (United States)

    Käser, T; Pasternak, J A; Hamonic, G; Rieder, M; Lai, K; Delgado-Ortega, M; Gerdts, V; Meurens, F

    2016-05-01

    Chlamydiaceae is a family of intracellular bacteria causing a range of diverse pathological outcomes. The most devastating human diseases are ocular infections with C. trachomatis leading to blindness and genital infections causing pelvic inflammatory disease with long-term sequelae including infertility and chronic pelvic pain. In order to enable the comparison of experiments between laboratories investigating host-chlamydia interactions, the infectious titer has to be determined. Titer determination of chlamydia is most commonly performed via microscopy of host cells infected with a serial dilution of chlamydia. However, other methods including fluorescent ELISpot (Fluorospot) and DNA Chip Scanning Technology have also been proposed to enumerate chlamydia-infected cells. For viruses, flow cytometry has been suggested as a superior alternative to standard titration methods. In this study we compared the use of flow cytometry with microscopy and Fluorospot for the titration of C. suis as a representative of other intracellular bacteria. Titer determination via Fluorospot was unreliable, while titration via microscopy led to a linear read-out range of 16 - 64 dilutions and moderate reproducibility with acceptable standard deviations within and between investigators. In contrast, flow cytometry had a vast linear read-out range of 1,024 dilutions and the lowest standard deviations given a basic training in these methods. In addition, flow cytometry was faster and material costs were lower compared to microscopy. Flow cytometry offers a fast, cheap, precise, and reproducible alternative for the titration of intracellular bacteria like C. suis. © 2016 International Society for Advancement of Cytometry. © 2016 International Society for Advancement of Cytometry.

  1. Bloom of resident antibiotic-resistant bacteria in soil following manure fertilization.

    OpenAIRE

    Udikovic-Kolic Nikolina; Wichmann Fabienne; Broderick Nichole A; Handelsman Jo

    2014-01-01

    The increasing prevalence of antibiotic resistant bacteria is a global threat to public health. Agricultural use of antibiotics is believed to contribute to the spread of antibiotic resistance but the mechanisms by which many agricultural practices influence resistance remain obscure. Although manure from dairy farms is a common soil amendment in crop production its impact on the soil microbiome and resistome is not known. To gain insight into this impact we cultured bacteria from soil before...

  2. Coprinopsis cinerea intracellular lactonases hydrolyze quorum sensing molecules of Gram-negative bacteria.

    Science.gov (United States)

    Stöckli, Martina; Lin, Chia-Wei; Sieber, Ramon; Plaza, David F; Ohm, Robin A; Künzler, Markus

    2017-05-01

    Biofilm formation on fungal hyphae and production of antifungal molecules are strategies of bacteria in their competition with fungi for nutrients. Since these strategies are often coordinated and under control of quorum sensing by the bacteria, interference with this bacterial communication system can be used as a counter-strategy by the fungi in this competition. Hydrolysis of N-acyl-homoserine lactones (HSL), a quorum sensing molecule used by Gram-negative bacteria, by fungal cultures has been demonstrated. However, the enzymes that are responsible for this activity, have not been identified. In this study, we identified and characterized two paralogous HSL hydrolyzing enzymes from the coprophilous fungus Coprinopsis cinerea. The C. cinerea HSL lactonases belong to the metallo-β-lactamase family and show sequence homology to and a similar biochemical activity as the well characterized lactonase AiiA from Bacillus thuringiensis. We show that the fungal lactonases, similar to the bacterial enzymes, are kept intracellularly and act as a sink for the bacterial quorum sensing signals both in C. cinerea and in Saccharomyces cerevisiae expressing C. cinerea lactonases, due to the ability of these signal molecules to diffuse over the fungal cell wall and plasma membrane. The two isogenes coding for the C. cinerea HSL lactonases are arranged in the genome as a tandem repeat and expressed preferentially in vegetative mycelium. The occurrence of orthologous genes in genomes of other basidiomycetes appears to correlate with a saprotrophic lifestyle. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Coxiella burnetii transcriptional analysis reveals serendipity clusters of regulation in intracellular bacteria.

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    Quentin Leroy

    Full Text Available Coxiella burnetii, the causative agent of the zoonotic disease Q fever, is mainly transmitted to humans through an aerosol route. A spore-like form allows C. burnetii to resist different environmental conditions. Because of this, analysis of the survival strategies used by this bacterium to adapt to new environmental conditions is critical for our understanding of C. burnetii pathogenicity. Here, we report the early transcriptional response of C. burnetii under temperature stresses. Our data show that C. burnetii exhibited minor changes in gene regulation under short exposure to heat or cold shock. While small differences were observed, C. burnetii seemed to respond similarly to cold and heat shock. The expression profiles obtained using microarrays produced in-house were confirmed by quantitative RT-PCR. Under temperature stresses, 190 genes were differentially expressed in at least one condition, with a fold change of up to 4. Globally, the differentially expressed genes in C. burnetii were associated with bacterial division, (pppGpp synthesis, wall and membrane biogenesis and, especially, lipopolysaccharide and peptidoglycan synthesis. These findings could be associated with growth arrest and witnessed transformation of the bacteria to a spore-like form. Unexpectedly, clusters of neighboring genes were differentially expressed. These clusters do not belong to operons or genetic networks; they have no evident associated functions and are not under the control of the same promoters. We also found undescribed but comparable clusters of regulation in previously reported transcriptomic analyses of intracellular bacteria, including Rickettsia sp. and Listeria monocytogenes. The transcriptomic patterns of C. burnetii observed under temperature stresses permits the recognition of unpredicted clusters of regulation for which the trigger mechanism remains unidentified but which may be the result of a new mechanism of epigenetic regulation.

  4. Accelerated microevolution in an outer membrane protein (OMP of the intracellular bacteria Wolbachia

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    Russell Jacob A

    2010-02-01

    Full Text Available Abstract Background Outer membrane proteins (OMPs of Gram-negative bacteria are key players in the biology of bacterial-host interactions. However, while considerable attention has been given to OMPs of vertebrate pathogens, relatively little is known about the role of these proteins in bacteria that primarily infect invertebrates. One such OMP is found in the intracellular bacteria Wolbachia, which are widespread symbionts of arthropods and filarial nematodes. Recent experimental studies have shown that the Wolbachia surface protein (WSP can trigger host immune responses and control cell death programming in humans, suggesting a key role of WSP for establishment and persistence of the symbiosis in arthropods. Results Here we performed an analysis of 515 unique alleles found in 831 Wolbachia isolates, to investigate WSP structure, microevolution and population genetics. WSP shows an eight-strand transmembrane β-barrel structure with four extracellular loops containing hypervariable regions (HVRs. A clustering approach based upon patterns of HVR haplotype diversity was used to group similar WSP sequences and to estimate the relative contribution of mutation and recombination during early stages of protein divergence. Results indicate that although point mutations generate most of the new protein haplotypes, recombination is a predominant force triggering diversity since the very first steps of protein evolution, causing at least 50% of the total amino acid variation observed in recently diverged proteins. Analysis of synonymous variants indicates that individual WSP protein types are subject to a very rapid turnover and that HVRs can accommodate a virtually unlimited repertoire of peptides. Overall distribution of WSP across hosts supports a non-random association of WSP with the host genus, although extensive horizontal transfer has occurred also in recent times. Conclusions In OMPs of vertebrate pathogens, large recombination impact, positive

  5. Bioavailability of mineral-bound iron to a snow algae-bacteria co-culture and implications for albedo-altering snow algae blooms.

    Science.gov (United States)

    Harrold, Z R; Hausrath, E M; Garcia, A H; Murray, A E; Tschauner, O; Raymond, J; Huang, S

    2018-01-26

    Snow algae can form large-scale blooms across the snowpack surface and near-surface environments. These pigmented blooms can decrease snow albedo, increase local melt rates, and may impact the global heat budget and water cycle. Yet, underlying causes for the geospatial occurrence of these blooms remain unconstrained. One possible factor contributing to snow algae blooms is the presence of mineral dust as a micronutrient source. We investigated the bioavailability of iron (Fe) -bearing minerals, including forsterite (Fo 90 , Mg 1.8 Fe 0.2 SiO 4 ), goethite, smectite and pyrite as Fe sources for a Chloromonas brevispina - bacteria co-culture through laboratory-based experimentation. Fo 90 was capable of stimulating snow algal growth and increased the algal growth rate in otherwise Fe-depleted co-cultures. Fo 90 -bearing systems also exhibited a decrease in bacteria:algae ratios compared to Fe-depleted conditions, suggesting a shift in microbial community structure. The C. brevispina co-culture also increased the rate of Fo 90 dissolution relative to an abiotic control. Analysis of 16S rRNA genes in the co-culture identified Gammaproteobacteria , Betaprotoeobacteria and Sphingobacteria , all of which are commonly found in snow and ice environments. Archaea were not detected. Collimonas and Pseudomonas , which are known to enhance mineral weathering rates, comprised two of the top eight (> 1 %) OTUs. These data provide unequivocal evidence that mineral dust can support elevated snow algae growth under otherwise Fe-depleted growth conditions, and that snow algae can enhance mineral dissolution under these conditions. IMPORTANCE Fe, a key micronutrient for photosynthetic growth, is necessary to support the formation of high-density snow algae blooms. The laboratory experiments described herein allow for a systematic investigation of snow algae-bacteria-mineral interactions and their ability to mobilize and uptake mineral-bound Fe. Results provide unequivocal and

  6. Relationship between the Intracellular Integrity and the Morphology of the Capsular Envelope in Attached and Free-Living Marine Bacteria

    OpenAIRE

    Heissenberger, A.; Leppard, G. G.; Herndl, G. J.

    1996-01-01

    The integrity of the intracellular structures and the presence and dimension of the capsular envelope were investigated in marine snow-associated and marine free-living bacteria by transmission electron microscopy and special fixation techniques. Three categories depending on the presence of internal structures were differentiated. In marine snow, 51% of the marine snow-associated bacterial community was considered intact, 26% had a partly degraded internal structure, and 23% were empty with ...

  7. Enumeration of bacteria from a Trichodesmium spp. bloom of the eastern Arabian Sea: Elucidation of their possible role in biogeochemistry

    Digital Repository Service at National Institute of Oceanography (India)

    Basu, S.; Matondkar, S.G.P.; Furtado, I.

    ) and Bhatkal (13 degrees 58′N, 74 degrees 33′E) coasts. Visible bloom of ‘saw-dust’ color in the Ratnagiri shelf were microscopically examined and the presence of cyanobacteria Trichodesmium erythraeum and T. thieabautii with cell concentrations as high as 3...

  8. Visualizing early splenic memory CD8+ T cells reactivation against intracellular bacteria in the mouse.

    Directory of Open Access Journals (Sweden)

    Marc Bajénoff

    Full Text Available Memory CD8(+ T cells represent an important effector arm of the immune response in maintaining long-lived protective immunity against viruses and some intracellular bacteria such as Listeria monocytogenes (L.m. Memory CD8(+ T cells are endowed with enhanced antimicrobial effector functions that perfectly tail them to rapidly eradicate invading pathogens. It is largely accepted that these functions are sufficient to explain how memory CD8(+ T cells can mediate rapid protection. However, it is important to point out that such improved functional features would be useless if memory cells were unable to rapidly find the pathogen loaded/infected cells within the infected organ. Growing evidences suggest that the anatomy of secondary lymphoid organs (SLOs fosters the cellular interactions required to initiate naive adaptive immune responses. However, very little is known on how the SLOs structures regulate memory immune responses. Using Listeria monocytogenes (L.m as a murine infection model and imaging techniques, we have investigated if and how the architecture of the spleen plays a role in the reactivation of memory CD8(+ T cells and the subsequent control of L.m growth. We observed that in the mouse, memory CD8(+ T cells start to control L.m burden 6 hours after the challenge infection. At this very early time point, L.m-specific and non-specific memory CD8(+ T cells localize in the splenic red pulp and form clusters around L.m infected cells while naïve CD8(+ T cells remain in the white pulp. Within these clusters that only last few hours, memory CD8(+ T produce inflammatory cytokines such as IFN-gamma and CCL3 nearby infected myeloid cells known to be crucial for L.m killing. Altogether, we describe how memory CD8(+ T cells trafficking properties and the splenic micro-anatomy conjugate to create a spatio-temporal window during which memory CD8(+ T cells provide a local response by secreting effector molecules around infected cells.

  9. Multi locus sequence typing of Chlamydiales: clonal groupings within the obligate intracellular bacteria Chlamydia trachomatis

    NARCIS (Netherlands)

    Pannekoek, Yvonne; Morelli, Giovanna; Kusecek, Barica; Morré, Servaas A.; Ossewaarde, Jacobus M.; Langerak, Ankie A.; van der Ende, Arie

    2008-01-01

    BACKGROUND: The obligate intracellular growing bacterium Chlamydia trachomatis causes diseases like trachoma, urogenital infection and lymphogranuloma venereum with severe morbidity. Several serovars and genotypes have been identified, but these could not be linked to clinical disease or outcome.

  10. Modulation of Stat-1 in Human Macrophages Infected with Different Species of Intracellular Pathogenic Bacteria

    Directory of Open Access Journals (Sweden)

    Giuditta Fiorella Schiavano

    2016-01-01

    Full Text Available The infection of human macrophages by pathogenic bacteria induces different signaling pathways depending on the type of cellular receptors involved in the microorganism entry and on their mechanism(s of survival and replication in the host cell. It was reported that Stat proteins play an important role in this process. In the present study, we investigate the changes in Stat-1 activation (phosphorylation in p-tyr701 after uptake of two Gram-positive (Listeria monocytogenes and Staphylococcus aureus and two Gram-negative bacteria (Salmonella typhimurium and Legionella pneumophila characterized by their varying abilities to enter, survive, and replicate in human macrophages. Comparing the results obtained with Gram-negative and Gram-positive bacteria, Stat-1 activation in macrophages does not seem to be related to LPS content. The p-tyr701Stat-1 expression levels were found to be independent of the internalized bacterial number and IFN-γ release. On the contrary, Jak/Stat-1 pathway activation only occurs when an active infection has been established in the host macrophage, and it is plausible that the differences in the expression levels of p-tyr701Stat-1 could be due to different survival mechanisms or to differences in bacteria life cycles within macrophages.

  11. Investigation of Endophytic Bacterial Community in Supposedly Axenic Cultures of Pineapple and Orchids with Evidence on Abundant Intracellular Bacteria.

    Science.gov (United States)

    Esposito-Polesi, Natalia Pimentel; de Abreu-Tarazi, Monita Fiori; de Almeida, Cristina Vieira; Tsai, Siu Mui; de Almeida, Marcílio

    2017-01-01

    Asepsis, defined as the absence of microbial contamination, is one of the most important requirements of plant micropropagation. In long-term micropropagated cultures, there may occasionally occur scattered microorganism growth in the culture medium. These microorganisms are common plant components and are known as latent endophytes. Thus, the aim of this research was to investigate the presence of endophytic bacteria in asymptomatic pineapple and orchid microplants, which were cultivated in three laboratories for 1 year. Isolation and characterization of bacterial isolates, PCR-DGGE from total genomic DNA of microplants and ultrastructural analysis of leaves were performed. In the culture-dependent technique, it was only possible to obtain bacterial isolates from pineapple microplants. In this case, the bacteria genera identified in the isolation technique were Bacillus, Acinetobacter, and Methylobacterium. The scanning electron microscopy and transmission electron microscopy (SEM and TEM) analyses revealed the presence of endophytic bacteria in intracellular spaces in the leaves of pineapple and orchid microplants, independent of the laboratory or cultivation protocol. Our results strongly indicate that there are endophytic bacterial communities inhabiting the microplants before initiation of the in vitro culture and that some of these endophytes persist in their latent form and can also grow in the culture medium even after long-term micropropagation, thus discarding the concept of "truly axenic plants."

  12. Morphology and Phylogeny of the Soil Ciliate Metopus yantaiensis n. sp. (Ciliophora, Metopida), with Identification of the Intracellular Bacteria.

    Science.gov (United States)

    Omar, Atef; Zhang, Qianqian; Zou, Songbao; Gong, Jun

    2017-11-01

    The morphology and infraciliature of a new ciliate, Metopus yantaiensis n. sp., discovered in coastal soil of northern China, were investigated. It is distinguished from its congeners by a combination of the following features: nuclear apparatus situated in the preoral dome; 18-21 somatic ciliary rows, of which three extend onto the preoral dome (dome kineties); three to five distinctly elongated caudal cilia, and 21-29 adoral polykinetids. The 18S rRNA genes of this new species and two congeners, Metopus contortus and Metopus hasei, were sequenced and phylogenetically analyzed. The new species is more closely related to M. hasei and the clevelandellids than to other congeners; both the genus Metopus and the order Metopida are not monophyletic. In addition, the digestion-resistant bacteria in the cytoplasm of M. yantaiensis were identified, using a 16S rRNA gene clone library, sequencing, and fluorescence in situ hybridization. The detected intracellular bacteria are affiliated with Sphingomonadales, Rhizobiales, Rickettsiales (Alphaproteobacteria), Pseudomonas (Gammaproteobacteria), Rhodocyclales (Betaproteobacteria), Clostridiales (Firmicutes), and Flavobacteriales (Bacteroidetes). © 2017 The Author(s) Journal of Eukaryotic Microbiology © 2017 International Society of Protistologists.

  13. Multi locus sequence typing of Chlamydiales: clonal groupings within the obligate intracellular bacteria Chlamydia trachomatis

    Directory of Open Access Journals (Sweden)

    Langerak Ankie A

    2008-02-01

    Full Text Available Abstract Background The obligate intracellular growing bacterium Chlamydia trachomatis causes diseases like trachoma, urogenital infection and lymphogranuloma venereum with severe morbidity. Several serovars and genotypes have been identified, but these could not be linked to clinical disease or outcome. The related Chlamydophila pneumoniae, of which no subtypes are recognized, causes respiratory infections worldwide. We developed a multi locus sequence typing (MLST scheme to understand the population genetic structure and diversity of these species and to evaluate the association between genotype and disease. Results A collection of 26 strains of C. trachomatis of different serovars and clinical presentation and 18 strains of C. pneumoniae were included in the study. For comparison, sequences of C. abortus, C. psittaci, C. caviae, C. felis, C. pecorum (Chlamydophila, C. muridarum (Chlamydia and of Candidatus protochlamydia and Simkania negevensis were also included. Sequences of fragments (400 – 500 base pairs from seven housekeeping genes (enoA, fumC, gatA, gidA, hemN, hlfX, oppA were analysed. Analysis of allelic profiles by eBurst revealed three non-overlapping clonal complexes among the C. trachomatis strains, while the C. pneumoniae strains formed a single group. An UPGMA tree produced from the allelic profiles resulted in three groups of sequence types. The LGV strains grouped in a single cluster, while the urogenital strains were distributed over two separated groups, one consisted solely of strains with frequent occurring serovars (E, D and F. The distribution of the different serovars over the three groups was not consistent, suggesting exchange of serovar encoding ompA sequences. In one instance, exchange of fumC sequences between strains of different groups was observed. Cluster analyses of concatenated sequences of the Chlamydophila and Chlamydia species together with those of Candidatus Protochlamydia amoebophila and Simkania

  14. Multi locus sequence typing of Chlamydiales: clonal groupings within the obligate intracellular bacteria Chlamydia trachomatis.

    Science.gov (United States)

    Pannekoek, Yvonne; Morelli, Giovanna; Kusecek, Barica; Morré, Servaas A; Ossewaarde, Jacobus M; Langerak, Ankie A; van der Ende, Arie

    2008-02-28

    The obligate intracellular growing bacterium Chlamydia trachomatis causes diseases like trachoma, urogenital infection and lymphogranuloma venereum with severe morbidity. Several serovars and genotypes have been identified, but these could not be linked to clinical disease or outcome. The related Chlamydophila pneumoniae, of which no subtypes are recognized, causes respiratory infections worldwide. We developed a multi locus sequence typing (MLST) scheme to understand the population genetic structure and diversity of these species and to evaluate the association between genotype and disease. A collection of 26 strains of C. trachomatis of different serovars and clinical presentation and 18 strains of C. pneumoniae were included in the study. For comparison, sequences of C. abortus, C. psittaci, C. caviae, C. felis, C. pecorum (Chlamydophila), C. muridarum (Chlamydia) and of Candidatus protochlamydia and Simkania negevensis were also included. Sequences of fragments (400 - 500 base pairs) from seven housekeeping genes (enoA, fumC, gatA, gidA, hemN, hlfX, oppA) were analysed. Analysis of allelic profiles by eBurst revealed three non-overlapping clonal complexes among the C. trachomatis strains, while the C. pneumoniae strains formed a single group. An UPGMA tree produced from the allelic profiles resulted in three groups of sequence types. The LGV strains grouped in a single cluster, while the urogenital strains were distributed over two separated groups, one consisted solely of strains with frequent occurring serovars (E, D and F). The distribution of the different serovars over the three groups was not consistent, suggesting exchange of serovar encoding ompA sequences. In one instance, exchange of fumC sequences between strains of different groups was observed. Cluster analyses of concatenated sequences of the Chlamydophila and Chlamydia species together with those of Candidatus Protochlamydia amoebophila and Simkania negevensis resulted in a tree identical to that

  15. Phg1/TM9 proteins control intracellular killing of bacteria by determining cellular levels of the Kil1 sulfotransferase in Dictyostelium.

    Directory of Open Access Journals (Sweden)

    Marion Le Coadic

    Full Text Available Dictyostelium discoideum has largely been used to study phagocytosis and intracellular killing of bacteria. Previous studies have shown that Phg1A, Kil1 and Kil2 proteins are necessary for efficient intracellular killing of Klebsiella bacteria. Here we show that in phg1a KO cells, cellular levels of lysosomal glycosidases and lysozyme are decreased, and lysosomal pH is increased. Surprisingly, overexpression of Kil1 restores efficient killing in phg1a KO cells without correcting these lysosomal anomalies. Conversely, kil1 KO cells are defective for killing, but their enzymatic content and lysosomal pH are indistinguishable from WT cells. The killing defect of phg1a KO cells can be accounted for by the observation that in these cells the stability and the cellular amount of Kil1 are markedly reduced. Since Kil1 is the only sulfotransferase characterized in Dictyostelium, an (unidentified sulfated factor, defective in both phg1a and kil1 KO cells, may play a key role in intracellular killing of Klebsiella bacteria. In addition, Phg1B plays a redundant role with Phg1A in controlling cellular amounts of Kil1 and intracellular killing. Finally, cellular levels of Kil1 are unaffected in kil2 KO cells, and Kil1 overexpression does not correct the killing defect of kil2 KO cells, suggesting that Kil2 plays a distinct role in intracellular killing.

  16. HDAC6 controls innate immune and autophagy responses to TLR-mediated signalling by the intracellular bacteria Listeria monocytogenes.

    Directory of Open Access Journals (Sweden)

    Olga Moreno-Gonzalo

    2017-12-01

    Full Text Available Recent evidence on HDAC6 function underlines its role as a key protein in the innate immune response to viral infection. However, whether HDAC6 regulates innate immunity during bacterial infection remains unexplored. To assess the role of HDAC6 in the regulation of defence mechanisms against intracellular bacteria, we used the Listeria monocytogenes (Lm infection model. Our data show that Hdac6-/- bone marrow-derived dendritic cells (BMDCs have a higher bacterial load than Hdac6+/+ cells, correlating with weaker induction of IFN-related genes, pro-inflammatory cytokines and nitrite production after bacterial infection. Hdac6-/- BMDCs have a weakened phosphorylation of MAPK signalling in response to Lm infection, suggesting altered Toll-like receptor signalling (TLR. Compared with Hdac6+/+ counterparts, Hdac6-/- GM-CSF-derived and FLT3L-derived dendritic cells show weaker pro-inflammatory cytokine secretion in response to various TLR agonists. Moreover, HDAC6 associates with the TLR-adaptor molecule Myeloid differentiation primary response gene 88 (MyD88, and the absence of HDAC6 seems to diminish the NF-κB induction after TLR stimuli. Hdac6-/- mice display low serum levels of inflammatory cytokine IL-6 and correspondingly an increased survival to a systemic infection with Lm. The impaired bacterial clearance in the absence of HDAC6 appears to be caused by a defect in autophagy. Hence, Hdac6-/- BMDCs accumulate higher levels of the autophagy marker p62 and show defective phagosome-lysosome fusion. These data underline the important function of HDAC6 in dendritic cells not only in bacterial autophagy, but also in the proper activation of TLR signalling. These results thus demonstrate an important regulatory role for HDAC6 in the innate immune response to intracellular bacterial infection.

  17. Impact of non-Legionella bacteria on the uptake and intracellular replication of Legionella pneumophila in Acanthamoeba castellanii and Naegleria lovaniensis.

    Science.gov (United States)

    Declerck, P; Behets, J; Delaedt, Y; Margineanu, A; Lammertyn, E; Ollevier, F

    2005-11-01

    In aquatic environments, Legionella pneumophila survives, in association with other bacteria, within biofilms by multiplying in free-living amoebae. The precise mechanisms underlying several aspects of the uptake and intracellular replication of L. pneumophila in amoebae, especially in the presence of other bacteria, remain unknown. In the present study, we examined the competitive effect of selected non-Legionella bacteria (Escherichia coli, Aeromonas hydrophila, Flavobacterium breve, and Pseudomonas aeruginosa) on the uptake of L. pneumophila serogroup 1 by the amoebae Acanthamoeba castellanii and Naegleria lovaniensis. We also investigated their possible influence on the intracellular replication of L. pneumophila in both amoeba species. Our results showed that the non-Legionella bacteria did not compete with L. pneumophila for uptake, suggesting that the amoeba hosts took in L. pneumophila through a specific and presumably highly efficient uptake mechanism. Living and heat-inactivated P. aeruginosa best supported the replication of L. pneumophila in N. lovaniensis and A. castellanii, respectively, whereas for both amoeba species, E. coli yielded the lowest number of replicated L. pneumophila. Furthermore, microscopic examination showed that 100% of the A. castellanii and only 2% of the N. lovaniensis population were infected with L. pneumophila at the end of the experiment. This study clearly shows the influence of some non-Legionella bacteria on the intracellular replication of L. pneumophila in A. castellanii and N. lovaniensis. It also demonstrates the different abilities of the two tested amoeba species to serve as a proper host for the replication and distribution of the human pathogen in man-made aquatic environments such as cooling towers, shower heads, and air conditioning systems with potential serious consequences for human health.

  18. Staphylococcal catalase protects intracellularly survived bacteria by destroying H2O2 produced by the murine peritoneal macrophages.

    Science.gov (United States)

    Das, Debaditya; Bishayi, Biswadev

    2009-08-01

    To determine the interrelationship between the hydrogen peroxide (H(2)O(2)) mediated killing and the potential role of bacterial catalase and SOD in the evasion of host defense, we examined three clinical isolates of Staphylococcus aureus and evaluated their intracellular survival mechanism within murine peritoneal macrophages. Fluorescent microscopy and bacterial colony-forming unit (cfu) count revealed that phagocytic capacity of murine peritoneal macrophages was highest after 2h of in vitro infection with S. aureus. To understand whether catalase and SOD contributing in the intracellular survival, were of bacterial origin or not, 3 amino 1,2,4 triazole (ATZ) and Diethyldithiocarbamic acid (DDC) were used to inhibit specifically macrophage derived catalase and SOD respectively. Catalase activity from the whole staphylococcal cell in presence of ATZ suggested that the released catalase were of extracellular origin. Scanning electron microscopy revealed the degraded host cell membrane integrity during prolonged infection. Purified bacterial catalase from the intracellularly survived S. aureus recovered after 5h of infection and its inhibition by ATZ in the zymography strengthened the scope of involvement of these anti-oxidants in the intracellular survival of S. aureus.

  19. Isolation and endotoxin activities of lipopolysaccharides from cyanobacterial cultures and complex water blooms and comparison with the effects of heterotrophic bacteria and green alga

    Czech Academy of Sciences Publication Activity Database

    Bernardová, Kateřina; Babica, Pavel; Maršálek, Blahoslav; Bláha, Luděk

    2008-01-01

    Roč. 28, č. 1 (2008), s. 72-77 ISSN 0260-437X R&D Projects: GA AV ČR(CZ) KJB6005411 Grant - others:Research Center of the Ministry of Education (CZ) IM6798593901 Institutional research plan: CEZ:AV0Z60170517; CEZ:AV0Z60050516 Source of funding: V - iné verejné zdroje Keywords : pyrogenicity * cyanobacteria * water bloom * lipopolysaccharide * LAL assay Subject RIV: EH - Ecology, Behaviour Impact factor: 2.127, year: 2008

  20. Testing the Metabolic Theory of Ecology with marine bacteria: Different temperature sensitivity of major phylogenetic groups during the spring phytoplankton bloom

    KAUST Repository

    Arandia-Gorostidi, Nestor

    2017-08-24

    Although temperature is a key driver of bacterioplankton metabolism, the effect of ocean warming on different bacterial phylogenetic groups remains unclear. Here, we conducted monthly short-term incubations with natural coastal bacterial communities over an annual cycle to test the effect of experimental temperature on the growth rates and carrying capacities of four phylogenetic groups: SAR11, Rhodobacteraceae, Gammaproteobacteria and Bacteroidetes. SAR11 was the most abundant group year-round as analysed by CARD-FISH, with maximum abundances in summer, while the other taxa peaked in spring. All groups, including SAR11, showed high temperature-sensitivity of growth rates and/or carrying capacities in spring, under phytoplankton bloom or post-bloom conditions. In that season, Rhodobacteraceae showed the strongest temperature response in growth rates, estimated here as activation energy (E, 1.43 eV), suggesting an advantage to outcompete other groups under warmer conditions. In summer E values were in general lower than 0.65 eV, the value predicted by the Metabolic Theory of Ecology (MTE). Contrary to MTE predictions, carrying capacity tended to increase with warming for all bacterial groups. Our analysis confirms that resource availability is key when addressing the temperature response of heterotrophic bacterioplankton. We further show that even under nutrient-sufficient conditions, warming differentially affected distinct bacterioplankton taxa. This article is protected by copyright. All rights reserved.

  1. A census of membrane-bound and intracellular signal transduction proteins in bacteria: Bacterial IQ, extroverts and introverts

    Directory of Open Access Journals (Sweden)

    Galperin Michael Y

    2005-06-01

    Full Text Available Abstract Background Analysis of complete microbial genomes showed that intracellular parasites and other microorganisms that inhabit stable ecological niches encode relatively primitive signaling systems, whereas environmental microorganisms typically have sophisticated systems of environmental sensing and signal transduction. Results This paper presents results of a comprehensive census of signal transduction proteins – histidine kinases, methyl-accepting chemotaxis receptors, Ser/Thr/Tyr protein kinases, adenylate and diguanylate cyclases and c-di-GMP phosphodiesterases – encoded in 167 bacterial and archaeal genomes, sequenced by the end of 2004. The data have been manually checked to avoid false-negative and false-positive hits that commonly arise during large-scale automated analyses and compared against other available resources. The census data show uneven distribution of most signaling proteins among bacterial and archaeal phyla. The total number of signal transduction proteins grows approximately as a square of genome size. While histidine kinases are found in representatives of all phyla and are distributed according to the power law, other signal transducers are abundant in certain phylogenetic groups but virtually absent in others. Conclusion The complexity of signaling systems differs even among closely related organisms. Still, it usually can be correlated with the phylogenetic position of the organism, its lifestyle, and typical environmental challenges it encounters. The number of encoded signal transducers (or their fraction in the total protein set can be used as a measure of the organism's ability to adapt to diverse conditions, the 'bacterial IQ', while the ratio of transmembrane receptors to intracellular sensors can be used to define whether the organism is an 'extrovert', actively sensing the environmental parameters, or an 'introvert', more concerned about its internal homeostasis. Some of the microorganisms with the

  2. A census of membrane-bound and intracellular signal transduction proteins in bacteria: bacterial IQ, extroverts and introverts.

    Science.gov (United States)

    Galperin, Michael Y

    2005-06-14

    Analysis of complete microbial genomes showed that intracellular parasites and other microorganisms that inhabit stable ecological niches encode relatively primitive signaling systems, whereas environmental microorganisms typically have sophisticated systems of environmental sensing and signal transduction. This paper presents results of a comprehensive census of signal transduction proteins--histidine kinases, methyl-accepting chemotaxis receptors, Ser/Thr/Tyr protein kinases, adenylate and diguanylate cyclases and c-di-GMP phosphodiesterases--encoded in 167 bacterial and archaeal genomes, sequenced by the end of 2004. The data have been manually checked to avoid false-negative and false-positive hits that commonly arise during large-scale automated analyses and compared against other available resources. The census data show uneven distribution of most signaling proteins among bacterial and archaeal phyla. The total number of signal transduction proteins grows approximately as a square of genome size. While histidine kinases are found in representatives of all phyla and are distributed according to the power law, other signal transducers are abundant in certain phylogenetic groups but virtually absent in others. The complexity of signaling systems differs even among closely related organisms. Still, it usually can be correlated with the phylogenetic position of the organism, its lifestyle, and typical environmental challenges it encounters. The number of encoded signal transducers (or their fraction in the total protein set) can be used as a measure of the organism's ability to adapt to diverse conditions, the 'bacterial IQ', while the ratio of transmembrane receptors to intracellular sensors can be used to define whether the organism is an 'extrovert', actively sensing the environmental parameters, or an 'introvert', more concerned about its internal homeostasis. Some of the microorganisms with the highest IQ, including the current leader Wolinella succinogenes

  3. A dose and time response Markov model for the in-host dynamics of infection with intracellular bacteria following inhalation: with application to Francisella tularensis.

    Science.gov (United States)

    Wood, R M; Egan, J R; Hall, I M

    2014-06-06

    In a novel approach, the standard birth-death process is extended to incorporate a fundamental mechanism undergone by intracellular bacteria, phagocytosis. The model accounts for stochastic interaction between bacteria and cells of the immune system and heterogeneity in susceptibility to infection of individual hosts within a population. Model output is the dose-response relation and the dose-dependent distribution of time until response, where response is the onset of symptoms. The model is thereafter parametrized with respect to the highly virulent Schu S4 strain of Francisella tularensis, in the first such study to consider a biologically plausible mathematical model for early human infection with this bacterium. Results indicate a median infectious dose of about 23 organisms, which is higher than previously thought, and an average incubation period of between 3 and 7 days depending on dose. The distribution of incubation periods is right-skewed up to about 100 organisms and symmetric for larger doses. Moreover, there are some interesting parallels to the hypotheses of some of the classical dose-response models, such as independent action (single-hit model) and individual effective dose (probit model). The findings of this study support experimental evidence and postulations from other investigations that response is, in fact, influenced by both in-host and between-host variability.

  4. "Candidatus Sonnebornia yantaiensis", a member of candidate division OD1, as intracellular bacteria of the ciliated protist Paramecium bursaria (Ciliophora, Oligohymenophorea).

    Science.gov (United States)

    Gong, Jun; Qing, Yao; Guo, Xiaohong; Warren, Alan

    2014-02-01

    An intracellular bacterium was discovered in an isolate of Paramecium bursaria from a freshwater pond in Yantai, China. The bacteria were abundant and exclusively found in the cytoplasm of the host which, along with the green alga Chlorella, formed a three-partner consortium that could survive in pure water for at least one week. Cloning, sequencing and phylogenetic analysis of the bacterial 16S rRNA gene showed that the bacterium belonged to the uncultured candidate division OD1, which usually forms part of the rare biosphere. Transmission electron microscopy and fluorescence in situ hybridization (FISH) with specific probes showed that the bacteria were usually located close to the perialgal membranes of endosymbiotic Chlorella cells, and occasionally irregularly distributed throughout the host cytoplasm. The name "Candidatus Sonnebornia yantaiensis" gen. nov., sp. nov. is proposed for the new bacterium. A strongly supported monophyletic subclade, OD1-p, which included the new species, was recognized and this study highlights that protists can be important hosts for rare bacterial taxa. Copyright © 2013 Elsevier GmbH. All rights reserved.

  5. BLOOM: BLoom filter based oblivious outsourced matchings.

    Science.gov (United States)

    Ziegeldorf, Jan Henrik; Pennekamp, Jan; Hellmanns, David; Schwinger, Felix; Kunze, Ike; Henze, Martin; Hiller, Jens; Matzutt, Roman; Wehrle, Klaus

    2017-07-26

    Whole genome sequencing has become fast, accurate, and cheap, paving the way towards the large-scale collection and processing of human genome data. Unfortunately, this dawning genome era does not only promise tremendous advances in biomedical research but also causes unprecedented privacy risks for the many. Handling storage and processing of large genome datasets through cloud services greatly aggravates these concerns. Current research efforts thus investigate the use of strong cryptographic methods and protocols to implement privacy-preserving genomic computations. We propose FHE-BLOOM and PHE-BLOOM, two efficient approaches for genetic disease testing using homomorphically encrypted Bloom filters. Both approaches allow the data owner to securely outsource storage and computation to an untrusted cloud. FHE-BLOOM is fully secure in the semi-honest model while PHE-BLOOM slightly relaxes security guarantees in a trade-off for highly improved performance. We implement and evaluate both approaches on a large dataset of up to 50 patient genomes each with up to 1000000 variations (single nucleotide polymorphisms). For both implementations, overheads scale linearly in the number of patients and variations, while PHE-BLOOM is faster by at least three orders of magnitude. For example, testing disease susceptibility of 50 patients with 100000 variations requires only a total of 308.31 s (σ=8.73 s) with our first approach and a mere 0.07 s (σ=0.00 s) with the second. We additionally discuss security guarantees of both approaches and their limitations as well as possible extensions towards more complex query types, e.g., fuzzy or range queries. Both approaches handle practical problem sizes efficiently and are easily parallelized to scale with the elastic resources available in the cloud. The fully homomorphic scheme, FHE-BLOOM, realizes a comprehensive outsourcing to the cloud, while the partially homomorphic scheme, PHE-BLOOM, trades a slight relaxation of security

  6. A multiomics approach to study the microbiome response to phytoplankton blooms.

    Science.gov (United States)

    Song, Liyan

    2017-06-01

    Phytoplankton blooms are predictable features of marine and freshwater habitats. Despite a good knowledge base of the environmental factors controlling blooms, complex interactions between the bacterial and archaeal communities and phytoplankton bloom taxa are only now emerging. Here, the current research on bacterial community's structural and functional response to phytoplankton blooms is reviewed and discussed and further research is proposed. More attention should be paid on structure and function of autotrophic bacteria and archaea during phytoplankton blooms. A multiomics integration approach is needed to investigate bacterial and archaeal communities' diversity, metabolic diversity, and biogeochemical functions of microbial interactions during phytoplankton blooms.

  7. Recurring patterns in bacterioplankton dynamics during coastal spring algae blooms

    Science.gov (United States)

    Teeling, Hanno; Fuchs, Bernhard M; Bennke, Christin M; Krüger, Karen; Chafee, Meghan; Kappelmann, Lennart; Reintjes, Greta; Waldmann, Jost; Quast, Christian; Glöckner, Frank Oliver; Lucas, Judith; Wichels, Antje; Gerdts, Gunnar; Wiltshire, Karen H; Amann, Rudolf I

    2016-01-01

    A process of global importance in carbon cycling is the remineralization of algae biomass by heterotrophic bacteria, most notably during massive marine algae blooms. Such blooms can trigger secondary blooms of planktonic bacteria that consist of swift successions of distinct bacterial clades, most prominently members of the Flavobacteriia, Gammaproteobacteria and the alphaproteobacterial Roseobacter clade. We investigated such successions during spring phytoplankton blooms in the southern North Sea (German Bight) for four consecutive years. Dense sampling and high-resolution taxonomic analyses allowed the detection of recurring patterns down to the genus level. Metagenome analyses also revealed recurrent patterns at the functional level, in particular with respect to algal polysaccharide degradation genes. We, therefore, hypothesize that even though there is substantial inter-annual variation between spring phytoplankton blooms, the accompanying succession of bacterial clades is largely governed by deterministic principles such as substrate-induced forcing. DOI: http://dx.doi.org/10.7554/eLife.11888.001 PMID:27054497

  8. T cell expression of IL-18R and DR3 is essential for non-cognate stimulation of Th1 cells and optimal clearance of intracellular bacteria.

    Science.gov (United States)

    Pham, Oanh H; O'Donnell, Hope; Al-Shamkhani, Aymen; Kerrinnes, Tobias; Tsolis, Renée M; McSorley, Stephen J

    2017-08-01

    Th1 cells can be activated by TCR-independent stimuli, but the importance of this pathway in vivo and the precise mechanisms involved require further investigation. Here, we used a simple model of non-cognate Th1 cell stimulation in Salmonella-infected mice to examine these issues. CD4 Th1 cell expression of both IL-18R and DR3 was required for optimal IFN-γ induction in response to non-cognate stimulation, while IL-15R expression was dispensable. Interestingly, effector Th1 cells generated by immunization rather than live infection had lower non-cognate activity despite comparable IL-18R and DR3 expression. Mice lacking T cell intrinsic expression of MyD88, an important adapter molecule in non-cognate T cell stimulation, exhibited higher bacterial burdens upon infection with Salmonella, Chlamydia or Brucella, suggesting that non-cognate Th1 stimulation is a critical element of efficient bacterial clearance. Thus, IL-18R and DR3 are critical players in non-cognate stimulation of Th1 cells and this response plays an important role in protection against intracellular bacteria.

  9. Phytoplankton-Associated Bacterial Community Composition and Succession during Toxic Diatom Bloom and Non-Bloom Events.

    Science.gov (United States)

    Sison-Mangus, Marilou P; Jiang, Sunny; Kudela, Raphael M; Mehic, Sanjin

    2016-01-01

    Pseudo-nitzschia blooms often occur in coastal and open ocean environments, sometimes leading to the production of the neurotoxin domoic acid that can cause severe negative impacts to higher trophic levels. Increasing evidence suggests a close relationship between phytoplankton bloom and bacterial assemblages, however, the microbial composition and succession during a bloom process is unknown. Here, we investigate the bacterial assemblages before, during and after toxic and non-toxic Pseudo-nitzschia blooms to determine the patterns of bacterial succession in a natural bloom setting. Opportunistic sampling of bacterial community profiles were determined weekly at Santa Cruz Municipal Wharf by 454 pyrosequencing and analyzed together with domoic acid levels, phytoplankton community and biomass, nutrients and temperature. We asked if the bacterial communities are similar between bloom and non-bloom events and if domoic acid or the presence of toxic algal species acts as a driving force that can significantly structure phytoplankton-associated bacterial communities. We found that bacterial diversity generally increases when Pseudo-nitzschia numbers decline. Furthermore, bacterial diversity is higher when the low-DA producing P. fraudulenta dominates the algal bloom while bacterial diversity is lower when high-DA producing P. australis dominates the algal bloom, suggesting that the presence of algal toxin can structure bacterial community. We also found bloom-related succession patterns among associated bacterial groups; Gamma-proteobacteria, were dominant during low toxic P. fraudulenta blooms comprising mostly of Vibrio spp., which increased in relative abundance (6-65%) as the bloom progresses. On the other hand, Firmicutes bacteria comprising mostly of Planococcus spp. (12-86%) dominate during high toxic P. australis blooms, with the bacterial assemblage showing the same bloom-related successional patterns in three independent bloom events. Other environmental

  10. Phytoplankton-associated bacterial community composition and succession during toxic diatom bloom and non-bloom events

    Directory of Open Access Journals (Sweden)

    Marilou P. Sison-Mangus

    2016-09-01

    Full Text Available Pseudo-nitzschia blooms often occur in coastal and open ocean environments, sometimes leading to the production of the neurotoxin domoic acid that can cause severe negative impacts to higher trophic levels. Increasing evidence suggests a close relationship between phytoplankton bloom and bacterial assemblages, however, the microbial composition and succession during a bloom process is unknown. Here, we investigate the bacterial assemblages before, during and after toxic and non-toxic Pseudo-nitzschia blooms to determine the patterns of bacterial succession in a natural bloom setting. Opportunistic sampling of bacterial community profiles were determined weekly at Santa Cruz Municipal Wharf by 454 pyrosequencing and analyzed together with domoic acid levels, phytoplankton community and biomass, nutrients and temperature. We asked if the bacterial communities are similar between bloom and non-bloom events and if domoic acid or the presence of toxic algal species acts as a driving force that can significantly structure phytoplankton-associated bacterial communities. We found that bacterial diversity generally increases when Pseudo-nitzschia numbers decline. Furthermore, bacterial diversity is higher when the low-DA producing P. fraudulenta dominates the algal bloom while bacterial diversity is lower when high-DA producing P. australis dominates the algal bloom, suggesting that the presence of algal toxin can structure bacterial community. We also found bloom-related succession patterns among associated bacterial groups; Gamma-proteobacteria, were dominant during low toxic P. fraudulenta blooms comprising mostly of Vibrio spp., which increased in relative abundance (6%-65% as the bloom progresses. On the other hand, Firmicutes bacteria comprising mostly of Planococcus spp. (12%- 86% dominate during high toxic P. australis blooms, with the bacterial assemblage showing the same bloom-related successional patterns in 3 independent bloom events. Other

  11. Dynamic Changes in Bacterial Population and Corresponding Exoenzyme Activity in Response to a Tropical Phytoplankton Bloom Chattonella marina

    Directory of Open Access Journals (Sweden)

    Anit M. Thomas

    2014-01-01

    Full Text Available The raphidophyte Chattonella marina (Subrahmanyan Hara & Chihara bloom which causes lethal effects on marine ecosystem has been reported intermittently from Indian waters. In the present study, periodic samplings were made in a Chattonella marina bloom area, off Mahe, on 27 and 29 October and 1 November 2011 (in different phases of the bloom to assess the associated bacterial population and their exoenzyme activity. Microbial community composition of Chattonella marina bloom revealed a twentyfold increase in bacterial load over the nonbloom area. The bacterial genera, Micrococcus, Flavobacterium, Vibrio, and Pseudomonas, increased significantly during the declining phase of the bloom. An assessment of the extracellular enzyme production also showed a marked increase in percentage of bacterial strains, potent in protease production, suggesting the possible role of proteolytic bacteria in bloom crash. This study reveals the bacterial community succession during the bloom and indicates that bacteria play an important role in bloom regulation.

  12. Genetics Home Reference: Bloom syndrome

    Science.gov (United States)

    ... 1 link) Bloom syndrome Sources for This Page Amor-Guéret M. Bloom syndrome, genomic instability and cancer: ... Zhang B, Zhang XD, Dou SX, Wang PY, Amor-Gueret M, Xi XG. Structural and functional analyses ...

  13. Byatt versus Bloom

    DEFF Research Database (Denmark)

    Børch, Marianne

    2016-01-01

    Antonia Byatt's Possession takes issue with Harold Bloom's famous claim that creation - including an author's creative reading of an intertext - entails a violent encounter. Byatt's book suggests a more positive Construction of the process by which tradition is transformed in transmission....

  14. Role of NKG2D and its ligands in the anti-infectious activity of Vγ9Vδ2 T cells against intracellular bacteria.

    Science.gov (United States)

    Bessoles, Stéphanie; Ni, Ming; Garcia-Jimenez, Sara; Sanchez, Françoise; Lafont, Virginie

    2011-06-01

    Human Vγ9Vδ2 T cells play a crucial role in early immune response to intracellular pathogens. Their number is drastically increased in the peripheral blood of patients during the acute phase of brucellosis. In vitro, Vγ9Vδ2 T cells exhibit strong cytolytic activity against Brucella-infected cells and impair intracellular growth of Brucella suis in autologous macrophages. Vγ9Vδ2 T cells use cell contact-dependent mechanisms such as the release of lytic granules and Fas-mediated signals to lyse infected macrophages and decrease the development of intracellular Brucella. Although the involvement of the T-cell receptor (TCR) in the triggering of these responses is known, other surface receptors can modulate Vγ9Vδ2 T-cell response. In this study, we have investigated a potential role of NKG2D and its ligands in the anti-infectious activity of human Vγ9Vδ2 T cells against B. suis. We show that the recruitment of NKG2D by its ligands is sufficient to induce cytokine production and the release of lytic granules through PI3K-dependent pathways, but can also increase the TCR-triggered responses of Vγ9Vδ2 T cells. We also demonstrate that the interaction between NKG2D and its main ligand expressed on Brucella-infected macrophages, UL16-binding protein 1 (ULBP1), is involved in the inhibition of bacterium development. Altogether, these results suggest a direct contribution of NKG2D and its ligands to the anti-infectious activity of Vγ9Vδ2 T cells. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Phytoplankton Bloom Off Portugal

    Science.gov (United States)

    2002-01-01

    Turquoise and greenish swirls marked the presence of a large phytoplankton bloom off the coast of Portugal on April 23, 2002. This true-color image was acquired by the Moderate-resolution Imaging Spectroradiometer (MODIS), flying aboard NASA's Terra satellite. There are also several fires burning in northwest Spain, near the port city of A Coruna. Please note that the high-resolution scene provided here is 500 meters per pixel. For a copy of this scene at the sensor's fullest resolution, visit the MODIS Rapidfire site.

  16. Making Culture Bloom

    Directory of Open Access Journals (Sweden)

    Iain McCalman

    2013-08-01

    Full Text Available On 16 June 1904, exactly one hundred years before the establishment of CHASS, an Irish Jew of Hungarian extraction called Leopold Bloom set off on a twenty-four hour perambulation around the streets and bars of Dublin. This fictional incident is the basis of James Joyce’s Ulysses, the greatest novel of modern times. It has also given rise to Bloomsday, a kind of Irish literary holy day celebrated in cities all around the world. It was a specially appropriate moment for us to celebrate the birth of our new peak body, because Bloomsday provides a perfect parable for why the Australian public and government should cherish our sector.

  17. Expression of genes involved in the uptake of inorganic carbon in the gill of a deep-sea vesicomyid clam harboring intracellular thioautotrophic bacteria.

    Science.gov (United States)

    Hongo, Yuki; Ikuta, Tetsuro; Takaki, Yoshihiro; Shimamura, Shigeru; Shigenobu, Shuji; Maruyama, Tadashi; Yoshida, Takao

    2016-07-10

    Deep-sea vesicomyid clams, including the genus Phreagena (formerly Calyptogena), harbor thioautotrophic bacterial symbionts in the host symbiosome, which consists of cytoplasmic vacuoles in gill epithelial cells called bacteriocytes. The symbiont requires inorganic carbon (Ci), such as CO2, HCO3(-), and CO3(2-), to synthesize organic compounds, which are utilized by the host clam. The dominant Ci in seawater is HCO3(-), which is impermeable to cell membranes. Within the bacteriocyte, cytoplasmic carbonic anhydrase (CA) from the host, which catalyzes the inter-conversion between CO2 and HCO3(-), has been shown to be abundant and is thought to supply intracellular CO2 to symbionts in the symbiosome. However, the mechanism of Ci uptake by the host gill from seawater is poorly understood. To elucidate the influx pathway of Ci into the bacteriocyte, we isolated the genes related to Ci uptake via the pyrosequencing of cDNA from the gill of Phreagena okutanii, and investigated their expression patterns. Using phylogenetic and amino acid sequence analyses, three solute carrier family 4 (SLC4) bicarbonate transporters (slc4co1, slc4co2, and slc4co4) and two membrane-associated CAs (mcaco1 and mcaco2) were identified as candidate genes for Ci uptake. In an in situ hybridization analysis of gill sections, the expression of mcaco1 and mcaco2 was detected in the bacteriocytes and asymbiotic non-ciliated cells, respectively, and the expression of slc4co1 and slc4co2 was detected in the asymbiotic cells, including the intermediate cells of the inner area and the non-ciliated cells of the external area. Although subcellular localizations of the products of these genes have not been fully elucidated, they may play an important role in the uptake of Ci into the bacteriocytes. These findings will improve our understanding of the Ci transport system in the symbiotic relationships of chemosynthetic bivalves. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Harold Bloom : canon e influencia

    OpenAIRE

    Pérez Vázquez, Ángel

    1998-01-01

    This essay is intended as an introduction to some of the most important aspects of the critical of the North American literary critic and theorist. Harold Bloom. The point of view from which these pages are written is mainly descriptive, and, to a very limited extent, polemical as well. The essay starts by outlining Bloom's visión of the Anglo- American literary canon, as well as his main theoretical tenets and intellectual sources. The main point of focus, though, is Bloom's theory...

  19. ECOHAB: Doucette_G- Algicidal bacteria and the regulation of Karenia brevis blooms in the Gulf of Mexico from 1998-11-16 to 1999-09-29 (NODC Accession 0000542)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Interactions between bacteria and species of harmful and/or toxic algae are potentially important factors affecting both the population dynamics and toxicity of...

  20. Algal Bloom: Boon or Bane?

    Digital Repository Service at National Institute of Oceanography (India)

    LokaBharathi, P.A.

    Algal blooms occur in response to nutrient deplete or replete conditions. Nitrogen fixing forms proliferate under oligotrophic conditions when nutrient levels are low. Replete conditions in response to upwelling creates the most biologically...

  1. OSU MODIS FLH Bloom Product

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Two bloom products were developed for the Oregon coast based on the observed change between running 8-day composite chlorophyll-a (CHL) and fluorescence line-height...

  2. Allan Bloom, America, and Education.

    Science.gov (United States)

    West, Thomas

    2000-01-01

    Refutes the claims of Allan Bloom that the source of the problem with today's universities is modern philosophy, that the writings and ideas of Hobbes and Locke planted the seeds of relativism in American culture, and that the cure is Great Books education. Suggests instead that America's founding principles are the only solution to the failure of…

  3. Seasonal assemblages and short-lived blooms in coastal north-west Atlantic Ocean bacterioplankton.

    Science.gov (United States)

    El-Swais, Heba; Dunn, Katherine A; Bielawski, Joseph P; Li, William K W; Walsh, David A

    2015-10-01

    Temperate oceans are inhabited by diverse and temporally dynamic bacterioplankton communities. However, the role of the environment, resources and phytoplankton dynamics in shaping marine bacterioplankton communities at different time scales remains poorly constrained. Here, we combined time series observations (time scales of weeks to years) with molecular analysis of formalin-fixed samples from a coastal inlet of the north-west Atlantic Ocean to show that a combination of temperature, nitrate, small phytoplankton and Synechococcus abundances are best predictors for annual bacterioplankton community variability, explaining 38% of the variation. Using Bayesian mixed modelling, we identified assemblages of co-occurring bacteria associated with different seasonal periods, including the spring bloom (e.g. Polaribacter, Ulvibacter, Alteromonadales and ARCTIC96B-16) and the autumn bloom (e.g. OM42, OM25, OM38 and Arctic96A-1 clades of Alphaproteobacteria, and SAR86, OM60 and SAR92 clades of Gammaproteobacteria). Community variability over spring bloom development was best explained by silicate (32%)--an indication of rapid succession of bacterial taxa in response to diatom biomass--while nanophytoplankton as well as picophytoplankton abundance explained community variability (16-27%) over the transition into and out of the autumn bloom. Moreover, the seasonal structure was punctuated with short-lived blooms of rare bacteria including the KSA-1 clade of Sphingobacteria related to aromatic hydrocarbon-degrading bacteria. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

  4. Dinoflagellate blooms in upwelling systems: Seeding, variability, and contrasts with diatom bloom behaviour

    Science.gov (United States)

    Smayda, T. J.; Trainer, V. L.

    2010-04-01

    The influence of diatom bloom behaviour, dinoflagellate life cycles, propagule type and upwelling bloom cycles on the seeding of dinoflagellate blooms in eastern boundary current upwelling systems is evaluated. Winter-spring diatom bloom behaviour is contrasted with upwelling bloom behaviour because their phenology impacts dinoflagellate blooms. The winter-spring diatom bloom is usually sustained, whereas the classical upwelling diatom bloom occurs as a series of separate, recurrent mini-blooms intercalated by upwelling-relaxation periods, during which dinoflagellates often bloom. Four sequential wind-regulated phases characterize upwelling cycles, with each phase having different effects on diatom and dinoflagellate bloom behaviour: bloom “spin up”, bloom maximum, bloom “spin down”, and upwelling relaxation. The spin up - bloom maximum is the period of heightened diatom growth; the spin down - upwelling-relaxation phases are the periods when dinoflagellates often bloom. The duration, intensity and ratio of the upwelling and relaxation periods making up upwelling cycles determine the potential for dinoflagellate blooms to develop within a given upwelling cycle and prior to the subsequent “spin up” of upwelling that favours diatom blooms. Upwelling diatoms and meroplanktonic dinoflagellates have three types of propagules available to seed blooms: vegetative cells, resting cells and resting cysts. However, most upwelling dinoflagellates are holoplanktonic, which indicates that the capacity to form resting cysts is not an absolute requirement for growth and survival in upwelling systems. The long-term (decadal) gaps in bloom behaviour of Gymnodinium catenatum and Lingulodinium polyedrum, and the unpredictable bloom behaviour of dinoflagellates generally, are examined from the perspective of seeding strategies. Mismatches between observed and expected in situ bloom behaviour and resting cyst dynamics are common among upwelling dinoflagellates. This

  5. Dangerous jellyfish blooms are predictable.

    Science.gov (United States)

    Gershwin, Lisa-ann; Condie, Scott A; Mansbridge, Jim V; Richardson, Anthony J

    2014-07-06

    The potentially fatal Irukandji syndrome is relatively common in tropical waters throughout the world. It is caused by the sting of the Irukandji jellyfish, a family of box jellyfish that are almost impossible to detect in the water owing to their small size and transparency. Using collated medical records of stings and local weather conditions, we show that the presence of Irukandji blooms in coastal waters can be forecast on the basis of wind conditions. On the Great Barrier Reef, blooms largely coincide with relaxation of the prevailing southeasterly trade winds, with average conditions corresponding to near zero alongshore wind on the day prior to the sting. These conditions are consistent with hypotheses long held by local communities and provide a basis for designing management interventions that have the potential to eliminate the majority of stings. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  6. Modelling the production of dimethylsulfide during a phytoplankton bloom

    Science.gov (United States)

    Gabric, Albert; Murray, Nicholas; Stone, Lewi; Kohl, Manfred

    1993-12-01

    Dimethylsulfide (DMS) is an important sulfur-containing atmospheric trace gas of marine biogenic origin. DMS emitted from the oceans may be a precursor of tropospheric aerosols and cloud condensation nuclei (CCN), thereby affecting the Earth's radiative balance and possibly constituting a negative feedback to global warming, although this hypothesis is still somewhat controversial. The revised conceptual model of the marine pelagic food web gives a central role to planktonic bacteria. Recent experiments have shown that consumption of dissolved DMS by microbial metabolism may be more important than atmospheric exchange in controlling its concentration in surface waters and hence its ventilation to the atmosphere. In this paper we investigate the effect of the marine food web on cycling of dissolved DMS in surface waters during a phytoplankton bloom episode. A nitrogen-based flow network simulation model has been used to analyze the relative importance of the various biological and chemical processes involved. The model predictions suggest that the concentration of DMS in marine surface waters is indeed governed by bacterial metabolism. Environmental factors that affect the bacterial compartment are thus likely to have a relatively large influence on dissolved DMS concentrations. The ecological succession is particularly sensitive to the ratio of phytoplankton to bacterial nutrient uptake rates as well the interaction between herbivore food chain and the microbial loop. Importantly for the design of field studies, the model predicts that peak DMS concentrations are achieved during the decline of the phytoplankton bloom with a typical time lag between peak DMS and peak phytoplankton biomass of 1 to 2 days. Significantly, the model predicts a relatively high DMS concentration persisting after the phytoplankton bloom due to excretion from large protozoa and zooplankton, which may be an additional explanation for the lack of correlation between DMS and chlorophyll a

  7. Algae Bloom in a Lake

    Directory of Open Access Journals (Sweden)

    David Sanabria

    2008-01-01

    Full Text Available The objective of this paper is to determine the likelihood of an algae bloom in a particular lake located in upstate New York. The growth of algae in this lake is caused by a high concentration of phosphorous that diffuses to the surface of the lake. Our calculations, based on Fick's Law, are used to create a mathematical model of the driving force of diffusion for phosphorous. Empirical observations are also used to predict whether the concentration of phosphorous will diffuse to the surface of this lake within a specified time and under specified conditions.

  8. Algal blooms and Membrane Based Desalination Technology

    NARCIS (Netherlands)

    Villacorte, L.O.

    2014-01-01

    Seawater desalination is rapidly growing in terms of installed capacity (~80 million m3/day in 2013), plant size and global application. An emerging threat to this technology is the seasonal proliferation of microscopic algae in seawater known as algal blooms. Such blooms have caused operational

  9. The Cartesian Heritage of Bloom's Taxonomy

    Science.gov (United States)

    Bertucio, Brett

    2017-01-01

    This essay seeks to contribute to the critical reception of "Bloom's Taxonomy of Educational Objectives" by tracing the Taxonomy's underlying philosophical assumptions. Identifying Bloom's work as consistent with the legacy of Cartesian thought, I argue that its hierarchy of behavioral objectives provides a framework for certainty and…

  10. Summer heatwaves promote blooms of harmful cyanobacteria

    NARCIS (Netherlands)

    K.D Joehnk; J. Huisman; J. Sharples; B.P. Sommeijer (Ben); P.M. Visser (Petra); J.M. Stroom

    2008-01-01

    htmlabstractDense surface blooms of toxic cyanobacteria in eutrophic lakes may lead to mass mortalities of fish and birds, and provide a serious health threat for cattle, pets, and humans. It has been argued that global warming may increase the incidence of harmful algal blooms. Here, we report on a

  11. Summer heatwaves promote blooms of harmful cyanobacteria

    NARCIS (Netherlands)

    Jöhnk, K.D.; Huisman, J.; Sharples, J.; Sommeijer, B.; Visser, P.M.; Stroom, J.M.

    2008-01-01

    Dense surface blooms of toxic cyanobacteria in eutrophic lakes may lead to mass mortalities of fish and birds, and provide a serious health threat for cattle, pets, and humans. It has been argued that global warming may increase the incidence of harmful algal blooms. Here, we report on a lake

  12. Heterotrophic bacterial responses to the winter–spring phytoplankton bloom in open waters of the NW Mediterranean

    KAUST Repository

    Gomes, Ana

    2014-12-03

    The response of planktonic heterotrophic prokaryotes to the NW Mediterranean winter–spring offshore phytoplankton bloom was assessed in 3 cruises conducted in March, April–May and September 2009. Bulk measurements of phytoplankton and bacterioplankton biomass and production were complemented with an insight into bacterial physiological structure by single-cell analysis of nucleic acid content [low (LNA) vs. high (HNA)] and membrane integrity (“Live” vs. “Dead” cells). Bacterial production empirical conversion factors (0.82±0.25 SE kg C mol leucine−1) were almost always well below the theoretical value. Major differences in most microbial variables were found among the 3 periods, which varied from extremely high phytoplankton biomass and production during the bloom in March (>1 g C m−2 d−1 primary production) to typically oligotrophic conditions during September stratification (<200 mg C m−2 d−1). In both these periods bacterial production was ~30 mg C m−2 d−1 while very large bacterial production (mean 228, with some stations exceeding 500 mg C m−2 d−1) but low biomass was observed during the April–May post-bloom phase. The contribution of HNA (30–67%) and “Live” cells (47–97%) were temporally opposite in the study periods, with maxima in March and September, respectively. Different relationships were found between physiological structure and bottom-up variables, with HNA bacteria apparently more responsive to phytoplankton only during the bloom, coinciding with larger average cell sizes of LNA bacteria. Moderate phytoplankton–bacterioplankton coupling of biomass and activity was only observed in the bloom and post-bloom phases, while relationships between both compartments were not significant under stratification. With all data pooled, bacteria were only weakly bottom-up controlled. Our analyses show that the biomass and production of planktonic algae and bacteria followed opposite paths in the transition from bloom to

  13. Host-Specificity and Dynamics in Bacterial Communities Associated with Bloom-Forming Freshwater Phytoplankton

    Science.gov (United States)

    Bagatini, Inessa Lacativa; Eiler, Alexander; Bertilsson, Stefan; Klaveness, Dag; Tessarolli, Letícia Piton; Vieira, Armando Augusto Henriques

    2014-01-01

    Many freshwater phytoplankton species have the potential to form transient nuisance blooms that affect water quality and other aquatic biota. Heterotrophic bacteria can influence such blooms via nutrient regeneration but also via antagonism and other biotic interactions. We studied the composition of bacterial communities associated with three bloom-forming freshwater phytoplankton species, the diatom Aulacoseira granulata and the cyanobacteria Microcystis aeruginosa and Cylindrospermopsis raciborskii. Experimental cultures incubated with and without lake bacteria were sampled in three different growth phases and bacterial community composition was assessed by 454-Pyrosequencing of 16S rRNA gene amplicons. Betaproteobacteria were dominant in all cultures inoculated with lake bacteria, but decreased during the experiment. In contrast, Alphaproteobacteria, which made up the second most abundant class of bacteria, increased overall during the course of the experiment. Other bacterial classes responded in contrasting ways to the experimental incubations causing significantly different bacterial communities to develop in response to host phytoplankton species, growth phase and between attached and free-living fractions. Differences in bacterial community composition between cyanobacteria and diatom cultures were greater than between the two cyanobacteria. Despite the significance, major differences between phytoplankton cultures were in the proportion of the OTUs rather than in the absence or presence of specific taxa. Different phytoplankton species favoring different bacterial communities may have important consequences for the fate of organic matter in systems where these bloom forming species occur. The dynamics and development of transient blooms may also be affected as bacterial communities seem to influence phytoplankton species growth in contrasting ways. PMID:24465807

  14. Host-specificity and dynamics in bacterial communities associated with Bloom-forming freshwater phytoplankton.

    Directory of Open Access Journals (Sweden)

    Inessa Lacativa Bagatini

    Full Text Available Many freshwater phytoplankton species have the potential to form transient nuisance blooms that affect water quality and other aquatic biota. Heterotrophic bacteria can influence such blooms via nutrient regeneration but also via antagonism and other biotic interactions. We studied the composition of bacterial communities associated with three bloom-forming freshwater phytoplankton species, the diatom Aulacoseira granulata and the cyanobacteria Microcystis aeruginosa and Cylindrospermopsis raciborskii. Experimental cultures incubated with and without lake bacteria were sampled in three different growth phases and bacterial community composition was assessed by 454-Pyrosequencing of 16S rRNA gene amplicons. Betaproteobacteria were dominant in all cultures inoculated with lake bacteria, but decreased during the experiment. In contrast, Alphaproteobacteria, which made up the second most abundant class of bacteria, increased overall during the course of the experiment. Other bacterial classes responded in contrasting ways to the experimental incubations causing significantly different bacterial communities to develop in response to host phytoplankton species, growth phase and between attached and free-living fractions. Differences in bacterial community composition between cyanobacteria and diatom cultures were greater than between the two cyanobacteria. Despite the significance, major differences between phytoplankton cultures were in the proportion of the OTUs rather than in the absence or presence of specific taxa. Different phytoplankton species favoring different bacterial communities may have important consequences for the fate of organic matter in systems where these bloom forming species occur. The dynamics and development of transient blooms may also be affected as bacterial communities seem to influence phytoplankton species growth in contrasting ways.

  15. Qualitative importance of the microbial loop and plankton community structure in a eutropic lake during a bloom of Cyanobacteria

    DEFF Research Database (Denmark)

    Christoffersen, K.

    1990-01-01

    carbon accounted for only 4-9% of bacterial carbon demand. Cyclopoid copepods and smallsized cladocerans started to grow after the culmination, but food limitation probably controlled the biomass after the collapse of the bloom. Grazing of micro- and macrozooplankton were estimated from in situ......, supporting the idea that ciliates are an important link between bacteria and higher trophic levels. During and after the bloom of Aphanizornenon, major fluxes of carbon between bacteria, ciliates and crustaceans were observed, and heterotrophic nanoflagellates played a minor role in the pelagic food web...

  16. (PHB)-producing bacteria

    African Journals Online (AJOL)

    Jane

    2011-06-06

    Jun 6, 2011 ... Bioplastics are naturally occurring biodegradable polymers made from polyhydroxyalkanoates (PHA) of which poly 3-hydroxy butyric acid ... The plastic polymers accumulate intracellularly as light- refracting amorphous ... study focuses on the isolation and identification of novel species of bacteria capable ...

  17. Dynamics of a cyanobacterial bloom in a hypereutrophic reservoir ...

    African Journals Online (AJOL)

    Blooming and non-blooming periods between 2004 and 2006 in a hypereutrophic reservoir, where cyanobacterial blooms have previously been reported to be permanent, presented an opportunity to characterise factors that may favour cyanobacterial dominance. As a bloom developed in May 2004, a shift to dominance by ...

  18. Detecting the Killer Toxin (Harmful Algal Blooms)

    International Nuclear Information System (INIS)

    Quevenco, Rodolfo

    2011-01-01

    IAEA is stepping up efforts to help countries understand the phenomenon and use more reliable methods for early detection and monitoring so as to limit harmful algal blooms (HABs) adverse effects on coastal communities everywhere.

  19. Climate Adaptation and Harmful Algal Blooms

    Science.gov (United States)

    EPA supports local, state and tribal efforts to maintain water quality. A key element of its efforts is to reduce excess nutrient pollution and the resulting adverse impacts, including harmful algal blooms.

  20. Winter bloom of a rare betaproteobacterium in the Arctic Ocean

    Directory of Open Access Journals (Sweden)

    Laura eAlonso-Saez

    2014-08-01

    Full Text Available Extremely low abundance microorganisms (members of the ‘rare biosphere’ are believed to include dormant taxa, which can sporadically become abundant following environmental triggers. Yet, microbial transitions from rare to abundant have seldom been captured in situ, and it is uncertain how widespread these transitions are. A bloom of a single ribotype (≥99% similarity in the 16S ribosomal RNA gene of a widespread betaproteobacterium (Janthinobacterium sp. occurred over two weeks in Arctic marine waters. The Janthinobacterium population was not detected microscopically in situ in January and early February, but suddenly appeared in the water column thereafter, eventually accounting for up to 20% of bacterial cells in mid February. During the bloom, this bacterium was detected at open water sites up to 50 km apart, being abundant down to more than 300 meters. This event is one of the largest monospecific bacterial blooms reported in polar oceans. It is also remarkable because Betaproteobacteria are typically found only in low abundance in marine environments. In particular, Janthinobacterium were known from non-marine habitats and had previously been detected only in the rare biosphere of seawater samples, including the polar oceans. The Arctic janthinobacterium formed mucilagenous monolayer aggregates after short (ca. 8 hours incubations, suggesting that biofilm formation may play a role in maintaining rare bacteria in pelagic marine environments. The spontaneous mass occurrence of this opportunistic rare taxon in polar waters during the energy-limited season extends current knowledge of how and when microbial transitions between rare and abundant occur in the ocean.

  1. Algal blooms increase heterotrophy at the base of boreal lake food webs-Evidence from fatty acid biomarkers

    NARCIS (Netherlands)

    Johansson, K.S.L.; Trigal, C.; Vrede, T.; van Rijswijk, P.; Goedkoop, W.; Johnson, R.K.

    2016-01-01

    Physical defenses and grazer avoidance of the bloom-forming microalga Gonyostomum semen may reduce the direct coupling between phytoplankton and higher trophic levels and result in an increased importance of alternative basal food resources such as bacteria and heterotrophic protozoans. To assess

  2. From MERIS To OLCI And Sentinel 2: Harmful Algal Bloom Applications & Modelling In South Africa

    Science.gov (United States)

    Robertson Lain, L.; Bernard, S.; Evers-King, H.; Matthews, M. W.; Smith, M.

    2013-12-01

    The Sentinel 2 and 3 missions offer new capabilities for Harmful Algal Bloom (HAB) observations in Southern Africa and further afield on the African continent where there is a great need for improved monitoring of water quality: both in freshwater resources where eutrophication is common, and in vulnerable coastal ecosystems. Two well validated algorithms - Equivalent Algal Populations (EAP) & Maximum Peak Height (MPH) - available for operational use on eutrophic waters are described. Spectral remote sensing reflectances (Rrs) and inherent optical properties (IOPs) are characterised via measurement and modelling of phytoplankton assemblages typical of high biomass algal blooms of the Southern Benguela and inland waters of South Africa. Sensitivity to phytoplankton functional types (PFTs) is investigated, with focus on optically significant biological characteristics e.g. particle size distribution and intracellular structure (including vacuoles).

  3. The Madagascar Bloom - a serendipitous study

    Science.gov (United States)

    Srokosz, M. A.; Quartly, G.

    2012-12-01

    The late austral summer (February-April) phytoplankton bloom that occurs east of Madagascar, exhibits significant interannual variability and at its largest extent covers ~1% of the world's ocean surface area. The bloom raises many intriguing questions about how it begins, is sustained, propagates to the east, exports carbon and ends. It has been observed and studied using satellite ocean colour observations, but the lack of in situ data makes it difficult to address these questions. Here we describe observations that were made on a cruise in February 2005 serendipitously. These show clearly for the first time the existence of both a deep chlorophyll maximum at ~70-110m depths (seen in SeaSoar fluorimeter data) and a surface chlorophyll signature (seen in SeaWiFS satellite ocean colour data). The observations also show the modulation of biological signature at the surface by the eddy field, but not apparently of the deep chlorophyll maximum. In situ observations indicate that Trichodesmium dominates the bloom nearer to Madagascar, while the diatom Rhizosolenia clevei (and its symbiont Richelia intracellularis) dominates further from the island. In addition, SeaSoar Optical Plankton Counter (OPC), temperature and salinity data suggest that the surface bloom seen in the SeaWiFS data is confined to the shallow (~30m) mixed layer. It is hypothesised that the interannual variability in bloom intensity may be due to variations in coastal upwelling and thus the supply of iron, which is a micronutrient that can limit diazotroph growth.

  4. The Madagascar Bloom: A serendipitous study

    Science.gov (United States)

    Srokosz, M. A.; Quartly, G. D.

    2013-01-01

    The late austral summer (February-April) phytoplankton bloom that occurs east of Madagascar exhibits significant interannual variability and at its largest extent covers 1% of the world's ocean surface area. The bloom raises many intriguing questions about how it begins, is sustained, propagates to the east, exports carbon, and ends. It has been observed and studied using satellite ocean color observations, but the lack of in situ data makes it difficult to address these questions. Here we describe observations that were made serendipitously on a cruise in February 2005. These show clearly for the first time the simultaneous existence of a deep chlorophyll maximum at 70-110 m depths (seen in SeaSoar fluorimeter data) and a surface chlorophyll signature [seen in Sea-viewing Wide Field-of-view Sensor (SeaWiFS) satellite ocean color data]. The observations also show the modulation of the biological signature at the surface by the eddy field but not of the deep chlorophyll maximum. Trichodesmium dominates the bloom nearer to Madagascar, while the diatom Rhizosolenia clevei (and its symbiont Richelia intracellularis) dominates further from the island. The surface bloom seen in the SeaWiFS data is confined to the shallow ( 30 m) mixed layer. It is hypothesized that the interannual variability in bloom intensity may be due to variations in coastal upwelling and thus the supply of iron, which is a micronutrient that can limit diazotroph growth.

  5. Advances in genetic manipulation of obligate intracellular bacterial pathogens

    Directory of Open Access Journals (Sweden)

    Paul eBeare

    2011-05-01

    Full Text Available Infections by obligate intracellular bacterial pathogens result in significant morbidity and mortality worldwide. These bacteria include Chlamydia spp., which causes millions of cases of sexually transmitted disease and blinding trachoma annually, and members of the α-proteobacterial genera Anaplasma, Ehrlichia, Orientia and Rickettsia, agents of serious human illnesses including epidemic typhus. Coxiella burnetii, the agent of human Q fever, has also been considered a prototypical obligate intracellular bacterium, but recent host cell-free (axenic growth has rescued it from obligatism. The historic genetic intractability of obligate intracellular bacteria has severely limited molecular dissection of their unique lifestyles and virulence factors involved in pathogenesis. Host cell restricted growth is a significant barrier to genetic transformation that can make simple procedures for free-living bacteria, such as cloning, exceedingly difficult. Low transformation efficiency requiring long term culture in host cells to expand small transformant populations is another obstacle. Despite numerous technical limitations, the last decade has witnessed significant gains in genetic manipulation of obligate intracellular bacteria including allelic exchange. Continued development of genetic tools should soon enable routine mutation and complementation strategies for virulence factor discovery and stimulate renewed interest in these refractory pathogens. In this review, we discuss the technical challenges associated with genetic transformation of obligate intracellular bacteria and highlight advances made with individual genera.

  6. Acquisition of an animal gene by microsporidian intracellular parasites

    OpenAIRE

    Selman, Mohammed; Pombert, Jean-François; Solter, Leellen; Farinelli, Laurent; Weiss, Louis M.; Keeling, Patrick; Corradi, Nicolas

    2011-01-01

    Parasites have adapted to their specialised way of life by a number of means, including the acquisition of genes by horizontal gene transfer. These newly acquired genes seem to come from a variety of sources, but seldom from the host, even in the most intimate associations between obligate intracellular parasite and host [1]. Microsporidian intracellular parasites have acquired a handful of genes, mostly from bacteria, that help them take energy from their hosts or protect them from the envir...

  7. Spring bloom onset in the Nordic Seas

    Science.gov (United States)

    Mignot, Alexandre; Ferrari, Raffaele; Mork, Kjell Arne

    2016-06-01

    The North Atlantic spring bloom is a massive annual growth event of marine phytoplankton, tiny free-floating algae that form the base of the ocean's food web and generates a large fraction of the global primary production of organic matter. The conditions that trigger the onset of the spring bloom in the Nordic Seas, at the northern edge of the North Atlantic, are studied using in situ data from six bio-optical floats released north of the Arctic Circle. It is often assumed that spring blooms start as soon as phytoplankton cells daily irradiance is sufficiently abundant that division rates exceed losses. The bio-optical float data instead suggest the tantalizing hypothesis that Nordic Seas blooms start when the photoperiod, the number of daily light hours experienced by phytoplankton, exceeds a critical value, independently of division rates. The photoperiod trigger may have developed at high latitudes where photosynthesis is impossible during polar nights and phytoplankton enters into a dormant stage in winter. While the first accumulation of biomass recorded by the bio-optical floats is consistent with the photoperiod hypothesis, it is possible that some biomass accumulation started before the critical photoperiod but at levels too low to be detected by the fluorometers. More precise observations are needed to test the photoperiod hypothesis.

  8. Cyanobacterial blooms in lake Atitlan, Guatemala

    Czech Academy of Sciences Publication Activity Database

    Rejmánková, E.; Komárek, Jiří; Dix, M.; Komárková, Jaroslava; Girón, N.

    2011-01-01

    Roč. 41, č. 4 (2011), s. 296-302 ISSN 0075-9511 Institutional research plan: CEZ:AV0Z60050516; CEZ:AV0Z60170517 Keywords : water blooms * plancton * Guatemala Subject RIV: EH - Ecology, Behaviour Impact factor: 1.527, year: 2011

  9. Plankton bloom controlled by horizontal stirring

    Science.gov (United States)

    McKiver, W.; Neufeld, Z.; Scheuring, I.

    2009-10-01

    Here we show a simple mechanism in which changes in the rate of horizontal stirring by mesoscale ocean eddies can trigger or suppress plankton blooms and can lead to an abrupt change in the average plankton density. We consider a single species phytoplankton model with logistic growth, grazing and a spatially non-uniform carrying capacity. The local dynamics have multiple steady states for some values of the carrying capacity that can lead to localized blooms as fluid moves across the regions with different properties. We show that for this model even small changes in the ratio of biological timescales relative to the flow timescales can greatly enhance or reduce the global plankton productivity. Thus, this may be a possible mechanism in which changes in horizontal mixing can trigger plankton blooms or cause regime shifts in some oceanic regions. Comparison between the spatially distributed model and Lagrangian simulations considering temporal fluctuations along fluid trajectories, demonstrates that small scale transport processes also play an important role in the development of plankton blooms with a significant influence on global biomass.

  10. Distance Sensitive Bloom Filters Without False Negatives

    DEFF Research Database (Denmark)

    Goswami, Mayank; Pagh, Rasmus; Silvestri, Francesco

    2017-01-01

    answers. Absence of false negatives is of critical importance in many applications of Bloom filters, so it is natural to ask if this can be also achieved in the distance sensitive setting. Our main contributions are upper and lower bounds (that are tight in several cases) for space usage in the distance...

  11. A Lagrangian View of Spring Phytoplankton Blooms

    Science.gov (United States)

    Kida, Shinichiro; Ito, Takamitsu

    2017-11-01

    The mechanisms of spring phytoplankton blooms are investigated from a Lagrangian framework by using a Lagrangian NPZD model that can track the movement and transfers of nutrient parcels in a turbulent environment. The model reveals that the onset of spring blooms depends on the cumulative euphotic age, which is the total time that inorganic nutrient is exposed to light before the photosynthetic conversion to phytoplankton biomass. A spring bloom, defined as a tenfold increase of near-surface phytoplankton, occurs when this cumulative euphotic age is approximately μeff-1·ln⁡10, where μeff is the effective growth rate in the euphotic layer, regardless of the underlying mechanism. If the turbulent layer depth is shallower than the critical depth and turbulence is strong, nutrient parcels accumulate enough light exposure through multiple entries to the sun-lit zone near the surface. If turbulence is weak, as that considered in the critical turbulence theory, the accumulation of the light exposure depends on the residence time of the nutrients parcels near the surface. The spectral shape of the cumulative euphotic age can clearly distinguish these two modes of spring blooms. The spectrum shows a peak at the theoretical growth timescale when multiple entries become important, while it shows a maximum near age zero that decays with age when the near-surface residence time becomes important. Mortality increases the cumulative euphotic age necessary for a bloom but does not affect the spectral shape, suggesting that it does not alter the primary mechanism behind the accumulation of cumulative euphotic age.

  12. Determination and occurrence of retinoids in a eutrophic lake (Taihu Lake, China): cyanobacteria blooms produce teratogenic retinal.

    Science.gov (United States)

    Wu, Xiaoqin; Jiang, Jieqiong; Hu, Jianying

    2013-01-15

    Besides retinoic acids (RAs), some retinoids such as retinal (RAL) and retinol (ROH), which are considered as RA precursors in vertebrates, are also reported to be teratogenic agents. In this study we investigated four RA precursors including RAL, ROH, retinyl palmitate, and β-carotene in the eutrophic Taihu Lake, China, by developing a sensitive analytical method. RAL and β-carotene were widely detected in natural cyanobacteria blooms and lake water. Intracellular concentrations of RAL and β-carotene in blooms were 9.4 to 6.9 × 10(3) and 3.4 to 1.8 × 10(5) ng L(-1), respectively, and their concentrations in lake water were up to 1.4 × 10 ng L(-1) (RAL) and 9.8 × 10(2) ng L(-1) (β-carotene). The good correlation between intracellular concentrations of RAL and RAs implied that RAL was involved in the production of RAs by cyanobacteria blooms. Further examination of 39 cyanobacteria and algae species revealed that most species could produce RAL and β-carotene. The greatest amount of RAL was found in Chlamydomonas sp. (FACHB-715; 1.9 × 10(3) ng g(-1) dry weight). As the main cyanobacteria in Taihu Lake, many Microcystis species could produce high amounts of RAL and were thought to greatly contribute to the production of RAL measured in the blooms. Productions of RAL and β-carotene by cyanobacteria were associated with species, origin location, and growth stage. The results in this study present the existence of a potential risk to aquatic animals living in a eutrophic environment from a high concentration of RAL in cyanobacteria blooms and also provide a clue for further investigating the mechanism underlying the biosynthetic pathway of RAs in cyanobacteria and algae.

  13. Distinct Bloom Dynamics of Toxic and Non-toxic Microcystis (Cyanobacteria) Subpopulations in Hoedong Reservoir (Korea).

    Science.gov (United States)

    Park, Bum Soo; Li, Zhun; Kang, Yoon-Ho; Shin, Hyeon Ho; Joo, Jae-Hyoung; Han, Myung-Soo

    2018-01-01

    Despite the importance of understanding the bloom mechanisms that influence cyanobacterial toxin production, the dynamics of toxic Microcystis subpopulations are largely unknown. Here, we quantified both toxic and entire (i.e., toxic and non-toxic) Microcystis populations based on the microcystin synthetase E (mcyE) and 16S ribosomal RNA genes. Samples were collected from pelagic water and sediments twice per week from October to December 2011, and we investigated the effects of physicochemical factors (pH, water temperature, dissolved oxygen, nutrients, etc.) and biological factors (ciliates and zooplankton) on the abundance of toxic and non-toxic Microcystis. During the study period, Microcystis blooms were composed of toxic and non-toxic subpopulations. Resting stage Microcystis in sediment may be closely linked to Microcystis populations in pelagic water and may contribute to the toxic subpopulation composition in surface Microcystis blooms. In pelagic water, the toxic and entire Microcystis population had a significant positive correlation with the pH and water temperature (p toxic to non-toxic Microcystis subpopulations was significantly (p stresses. These results suggest that the toxic and non-toxic subpopulations of Microcystis have distinct tolerance levels against these stressors. The intracellular microcystin (MC) concentration was positively associated with the abundance of the mcyE-positive Microcystis. By comparison, the MC concentration in pelagic water body (extracellular) increased when Microcystis was lysed due to environmental stresses.

  14. Subsurface phytoplankton blooms fuel pelagic production in the North Sea

    DEFF Research Database (Denmark)

    Richardson, Kathrine; Visser, Andre; Pedersen, Flemming

    2000-01-01

    relatively quickly from the water column and a large proportion of the material sedimenting to the bottom following the spring bloom is often comprised of intact phytoplankton cells. Thus, it is easy to argue that the spring bloom is fueling the energy demands of the benthos, but more difficult to argue......The seasonal phytoplankton biomass distribution pattern in stratified temperate marine waters is traditionally depicted as consisting of spring and autumn blooms. The energy source supporting pelagic summer production is believed to be the spring bloom. However, the spring bloom disappears...... convincingly that energy fixed during the spring bloom is fueling the pelagic production occurring during summer months. We argue here that periodic phytoplankton blooms are occurring during the summer in the North Sea at depths of >25 m and that the accumulated new production [sensu (Dugdale and Goering...

  15. Wind-driven marine phytoplank blooms: Satellite observation and analysis

    Science.gov (United States)

    Tang, DanLing

    2016-07-01

    Algal bloom is defined as a rapid increase or accumulation in biomass in an aquatic system. It not only can increase the primary production but also could result in negative ecological consequence, e.g.,Harmful Algal Blooms (HABs). According to the classic theory for the formation of algal blooms "critical depth" and "eutrophication", oligotrophic sea area is usually difficult to form a large area of algal blooms, and actuallythe traditional observation is only sporadic capture to the existence of algal blooms.Taking full advantage of multiple data of satellite remote sensing , this study introduces "Wind-driven algal blooms in open oceans: observation and mechanisms" It explained except classic coastal Ekman transport, the wind through a variety of mechanisms affecting the formation of algal blooms. Proposed a conceptual model of "Strong wind -upwelling-nutrient-phytoplankton blooms" in Western South China Sea (SCS) to assess role of wind-induced advection transport in phytoplankton bloom formation. It illustrates the nutrient resources that support long-term offshore phytoplankton blooms in the western SCS; (2)Proposal of the theory that "typhoons cause vertical mixing, induce phytoplankton blooms", and quantify their important contribution to marine primary production; Proposal a new ecological index for typhoon. Proposed remote sensing inversion models. (3)Finding of the spatial and temporaldistributions pattern of harmful algal bloom (HAB)and species variations of HAB in the South Yellow Sea and East China Sea, and in the Pearl River estuary, and their oceanic dynamic mechanisms related with monsoon; The project developed new techniques and generated new knowledge, which significantly improved understanding of the formation mechanisms of algal blooms. The proposed "wind-pump" mechanism integrates theoretical system combined "ocean dynamics, development of algal blooms, and impact on primary production", which will benefit fisheries management. These

  16. Siderophores: The special ingredient to cyanobacterial blooms

    Science.gov (United States)

    Du, Xue; Creed, Irena; Trick, Charles

    2013-04-01

    Freshwater lakes provide a number of significant ecological services including clean drinking water, habitat for aquatic biota, and economic benefits. The provision of these ecological services, as well as the health of these aquatic systems, is threatened by the excessive growth of algae, specifically, cyanobacteria. Historically, blooms have been linked to eutrophication but recent occurrences indicate that there are less dramatic changes that induce these blooms. Iron is an essential micronutrient required for specific essential metabolic pathways; however, the amount of biologically available iron in naturally occurring lake ranges from saturation to much lower than cell transport affinities. To assist in the modulation of iron availabilities, cyanobacteria in culture produce low molecular weight compounds that function in an iron binding and acquisition system; nevertheless, this has yet to be confirmed in naturally occurring lakes. This project explored the relationship of P, N and in particular, Fe, in the promotion of cyanobacteria harmful algal blooms in 30 natural freshwater lakes located in and around the Elk Island National Park, Alberta. It is hypothesized that cyanobacteria produce and utilize iron chelators called siderophores in low Fe and nitrogen (N) conditions, creating a competitive advantage over other algae in freshwater lakes. Lakes were selected to represent a range of iron availability to explore the nutrient composition of lakes that propagated cyanobacteria harmful algal blooms (cHABs) compared to lakes that did not. Lake water was analyzed for nutrients, microbial composition, siderophore concentration, and toxin concentration. Modifications were made to optimize the Czaky and Arnow tests for hydroxamate- and catecholate-type siderophores, respectively, for field conditions. Preliminary results indicate the presence of iron-binding ligands (0.11-2.34 mg/L) in freshwater lakes characterized by widely ranging Fe regimes (0.04-2.74 mg

  17. Plasticity of total and intracellular phosphorus quotas in Microcystis aeruginosa cultures and Lake Erie algal assemblages

    Directory of Open Access Journals (Sweden)

    Matthew A Saxton

    2012-01-01

    Full Text Available Blooms of the potentially toxic cyanobacterium Microcystis are common events globally, and as a result significant resources continue to be dedicated to monitoring and controlling these events. Recent studies have shown that a significant proportion total cell-associated phosphorus (P in phytoplankton can be surface adsorbed, and many of our current measurements do not accurately reflect the P demands of these organisms. In this study we measure the total cell-associated and intracellular P as well as growth rates of two toxic strains of Microcystis aeruginosa Kütz grown under a range of P concentrations. The results show that the intracellular P pool in Microcystis represents a percentage of total cell-associated P (50-90% similar to what has been reported for actively growing algae in marine systems. Intracellular P levels (39-147 fg cell-1 generally increased with increasing growth media P concentrations, but growth rate and the ratio of total cell-associated to intracellular P remained generally stable. Intracellular P quotas and growth rates in cells grown under the different P treatments illustrate the ability of this organism to successfully respond to changes in ambient P loads, and thus have implications for ecosystem scale productivity models employing P concentrations to predict algal bloom events.

  18. Isolation by Time During an Arctic Phytoplankton Spring Bloom.

    Science.gov (United States)

    Tammilehto, Anna; Watts, Phillip C; Lundholm, Nina

    2017-03-01

    The arctic phytoplankton spring bloom, which is often diatom-dominated, is a key event that provides the high latitude communities with a fundamental flux of organic carbon. During a bloom, phytoplankton may increase its biomass by orders of magnitude within days. Yet, very little is known about phytoplankton bloom dynamics, including for example how blooming affects genetic composition and diversity of a population. Here, we quantified the genetic composition and temporal changes of the diatom Fragilariopsis cylindrus, which is one of the most important primary producers in the Arctic, during the spring bloom in western Greenland, using 13 novel microsatellite markers developed for this study. We found that genetic differentiation (quantified using sample-specific F ST ) decreased between time points as the bloom progressed, with the most drastic changes in F ST occurring at the start of the bloom; thus the genetic structure of the bloom is characterized by isolation by time. There was little temporal variation in genetic diversity throughout the bloom (mean H E  = 0.57), despite marked fluctuations in F. cylindrus cell concentrations and the temporal change in sample-specific F ST . On the basis of this novel pattern of genetic differentiation, we suggest that blooming behavior may promote genetic diversity of a phytoplankton population. © 2016 The Author(s) Journal of Eukaryotic Microbiology © 2016 International Society of Protistologists.

  19. Stochastic Forecasting of Algae Blooms in Lakes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Peng; Tartakovsky, Daniel M.; Tartakovsky, Alexandre M.

    2013-01-15

    We consider the development of harmful algae blooms (HABs) in a lake with uncertain nutrients inflow. Two general frameworks, Fokker-Planck equation and the PDF methods, are developed to quantify the resultant concentration uncertainty of various algae groups, via deriving a deterministic equation of their joint probability density function (PDF). A computational example is examined to study the evolution of cyanobacteria (the blue-green algae) and the impacts of initial concentration and inflow-outflow ratio.

  20. Stochastic Forecasting of Algae Blooms in Lakes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Peng; Tartakovsky, Daniel M.; Tartakovsky, Alexandre M.

    2013-01-03

    We consider a general framework to predict the development of harmful algal blooms (HABs) in a lake driven by uncertain parameters. To quantify the concentration uncertainty of those algae groups via their joint probabilistic density function (PDF), we explore an approach based on the Fokker-Planck equation. Our result is presented in an example where abundant nutrients contribute to the proliferation of cyanobacteria and other minor algae groups.

  1. New Coccolithophore Bloom in Bering Sea

    Science.gov (United States)

    2002-01-01

    For the fourth year in a row it appears as if there is a bloom of coccolithophores-marine single-celled plants with calcite scales-in the Bering Sea off the coast of Alaska. Similar blooms were rare before 1997, but they have appeared every year since then. Scientists believe the coccolithophore blooms are the result of changing wind patterns in the region. Weaker than normal winds fail to mix the water of the Bering Sea, resulting in the growth of coccolithophores instead of other types of phytoplankton. Seabird populations have also been changing as a result of this climate change. The Sea-Viewing Wide Field-of-View Sensor (SeaWiFS), flying aboard the OrbView-2 satellite, saw the coccolith-brightened waters of the Bering Sea in 1997, 1998, and 1999. The waters have looked fairly bright again this winter and spring, as seen in this SeaWiFS image acquired April 29, 2000. But scientists are unsure whether this year's phenomenon is caused by living coccolithophorids, re-suspended coccoliths, or something else. Like all phytoplankton, coccolithophores contain chlorophyll and have the tendency to multiply rapidly near the surface. Yet, in large numbers, coccolithophores periodically shed their tiny scales, called 'coccoliths,' by the bucketful into the surrounding waters. The calcium-rich coccoliths turn the normally dark water a bright, milky aquamarine, making coccolithophore blooms easy to spot in satellite imagery. The edge of the whitish cloud in the water seen in this image is roughly 50 kilometers off the West Coast of Alaska. For more information see: SeaWiFS home page Changing Currents Color the Bering Sea a New Shade of Blue Image courtesy SeaWiFS project

  2. Merunut Pemahaman Taksonomi Bloom: Suatu Kontemplasi Filosofis

    Directory of Open Access Journals (Sweden)

    Dominikus Tulasi

    2010-10-01

    Full Text Available This article would like to share the use of Bloom's taxonomy as a cognitive framework for teaching-learning process to undertake the way student-centered learning. Related to the curriculum based competence in excellent education, the abstract cognitive in applying Bloom’s taxonomy is so called scaffolding. We know the taxonomy Bloom is a six-level classification system that uses observed student behavior to infer and absorb the level of cognitive achievement domain. This article surveys thinking within general education and management education, which uses and draws on Bloom's taxonomy, and then describes suggested uses of the taxonomy. The empirical evaluation of its effect on student achievement follows, as do thoughts about ways colleagues might use this tool to empower and motivate students as self-responsible learners in the classroom. The objective is to promote higher order thinking in college students, we understood an effort to learn how to assess critical-thinking skills in an introductory course. It means, we develop a process by which questions are prepared with both content and critical-thinking skills in mind. 

  3. Cell-penetrating antimicrobial peptides - prospectives for targeting intracellular infections

    DEFF Research Database (Denmark)

    Bahnsen, Jesper S; Franzyk, Henrik; Sayers, Edward J

    2015-01-01

    . TPk showed the highest antibacterial activity. SA-3 exhibited selective disruption of liposomes mimicking Gram-positive and Gram-negative membranes. CONCLUSION: PK-12-KKP is an unlikely candidate for targeting intracellular bacteria, as the eukaryotic cell-penetrating ability is poor. SA-3, affected...

  4. Distinct Network Interactions in Particle-Associated and Free-Living Bacterial Communities during a Microcystis aeruginosa Bloom in a Plateau Lake

    Directory of Open Access Journals (Sweden)

    Caiyun Yang

    2017-06-01

    Full Text Available Particle-associated bacteria (PAB and free-living bacteria (FLB from aquatic environments during phytoplankton blooms differ in their physical distance from algae. Both the interactions within PAB and FLB community fractions and their relationship with the surrounding environmental properties are largely unknown. Here, by using high-throughput sequencing and network-based analyses, we compared the community and network characteristics of PAB and FLB from a plateau lake during a Microcystis aeruginosa bloom. Results showed that PAB and FLB differed significantly in diversity, structure and microbial connecting network. PAB communities were characterized by highly similar bacterial community structure in different sites, tighter network connections, important topological roles for the bloom-causing M. aeruginosa and Alphaproteobacteria, especially for the potentially nitrogen-fixing (Pleomorphomonas and algicidal bacteria (Brevundimonas sp.. FLB communities were sensitive to the detected environmental factors and were characterized by significantly higher bacterial diversity, less connectivity, larger network size and marginal role of M. aeruginosa. In both networks, covariation among bacterial taxa was extensive (>88% positive connections, and bacteria potentially affiliated with biogeochemical cycling of nitrogen (i.e., denitrification, nitrogen-fixation and nitrite-oxidization were important in occupying module hubs, such as Meganema, Pleomorphomonas, and Nitrospira. These findings highlight the importance of considering microbial network interactions for the understanding of blooms.

  5. Phytoplankton as Particles - A New Approach to Modeling Algal Blooms

    Science.gov (United States)

    2013-07-01

    ER D C/ EL T R -1 3 -1 3 Civil Works Basic Research Program Phytoplankton as Particles – A New Approach to Modeling Algal Blooms E nv... Phytoplankton as Particles – A New Approach to Modeling Algal Blooms Carl F. Cerco and Mark R. Noel Environmental Laboratory U.S. Army Engineer Research... phytoplankton blooms can be modeled by treating phytoplankton as discrete particles capable of self- induced transport via buoyancy regulation or other

  6. Influence of Cyanobacterial Bloom on Freshwater Biocoenosis. Use of Bioassays for Cyanobacterial Microcystins Toxicity Assessment

    Directory of Open Access Journals (Sweden)

    Piontek Marlena

    2017-03-01

    Full Text Available The issues presented in this study concern a very important problem of the occurrence of cyanobacterial blooms in surface water used for water supply purposes. The objective of this study was to analyze the occurrence of cyanotoxic risk in the catchment area of the Obrzyca River (including Sławskie lake which is the beginning of the river, which is a source of drinking water for the inhabitants of Zielona Góra. In order to evaluate toxicity of cyanobacterial bloom it was conducted toxicological testing using aquatic invertebrates (Daphnia magna, Dugesia tigrina and heterotrophic bacteria (Escherichia coli, Enterococcus faecalis, Pseudomonas fluorescens. Test samples were collected from May to October, 2012. The most toxic was a sample collected from Lake Sławskie on 20th October when cyanobacteria bloom with a predominance of Microcystis aeruginosa occurred and the amount of microcystins was the largest. The methanol extract of the sample was toxic only above a concentration of 6·103 mg·dm-3. The lethal concentration (48-h LC 50 for Daphnia magna was 3.09·103 and for Dugesia tigrina (240-h LC 50 1.51·103 mg·dm-3 of microcystins (MC-LR, MC-YR and MC-RR. The same extract stimulated growth of Escherichia coli and Enterococcus faecalis cells.

  7. Biology in bloom: implementing Bloom's Taxonomy to enhance student learning in biology.

    Science.gov (United States)

    Crowe, Alison; Dirks, Clarissa; Wenderoth, Mary Pat

    2008-01-01

    We developed the Blooming Biology Tool (BBT), an assessment tool based on Bloom's Taxonomy, to assist science faculty in better aligning their assessments with their teaching activities and to help students enhance their study skills and metacognition. The work presented here shows how assessment tools, such as the BBT, can be used to guide and enhance teaching and student learning in a discipline-specific manner in postsecondary education. The BBT was first designed and extensively tested for a study in which we ranked almost 600 science questions from college life science exams and standardized tests. The BBT was then implemented in three different collegiate settings. Implementation of the BBT helped us to adjust our teaching to better enhance our students' current mastery of the material, design questions at higher cognitive skills levels, and assist students in studying for college-level exams and in writing study questions at higher levels of Bloom's Taxonomy. From this work we also created a suite of complementary tools that can assist biology faculty in creating classroom materials and exams at the appropriate level of Bloom's Taxonomy and students to successfully develop and answer questions that require higher-order cognitive skills.

  8. Selective algicidal action of peptides against harmful algal bloom species.

    Directory of Open Access Journals (Sweden)

    Seong-Cheol Park

    Full Text Available Recently, harmful algal bloom (HAB, also termed "red tide", has been recognized as a serious problem in marine environments according to climate changes worldwide. Many novel materials or methods to prevent HAB have not yet been employed except for clay dispersion, in which can the resulting sedimentation on the seafloor can also cause alteration in marine ecology or secondary environmental pollution. In the current study, we investigated that antimicrobial peptide have a potential in controlling HAB without cytotoxicity to harmless marine organisms. Here, antimicrobial peptides are proposed as new algicidal compounds in combating HAB cells. HPA3 and HPA3NT3 peptides which exert potent antimicrobial activity via pore forming action in plasma membrane showed that HPA3NT3 reduced the motility of algal cells, disrupted their plasma membrane, and induced the efflux of intracellular components. Against raphidoflagellate such as Heterosigma akashiwo, Chattonella sp., and C. marina, it displayed a rapid lysing action in cell membranes at 1~4 µM within 2 min. Comparatively, its lysing effects occurred at 8 µM within 1 h in dinoflagellate such as Cochlodium polykrikoides, Prorocentrum micans, and P. minimum. Moreover, its lysing action induced the lysis of chloroplasts and loss of chlorophyll a. In the contrary, this peptide was not effective against Skeletonema costatum, harmless algal cell, even at 256 µM, moreover, it killed only H. akashiwo or C. marina in co-cultivation with S. costatum, indicating to its selective algicidal activity between harmful and harmless algal cells. The peptide was non-hemolytic against red blood cells of Sebastes schlegeli, the black rockfish, at 120 µM. HAB cells were quickly and selectively lysed following treatment of antimicrobial peptides without cytotoxicity to harmless marine organisms. Thus, the antibiotic peptides examined in our study appear to have much potential in effectively controlling HAB with minimal

  9. Selective algicidal action of peptides against harmful algal bloom species.

    Science.gov (United States)

    Park, Seong-Cheol; Lee, Jong-Kook; Kim, Si Wouk; Park, Yoonkyung

    2011-01-01

    Recently, harmful algal bloom (HAB), also termed "red tide", has been recognized as a serious problem in marine environments according to climate changes worldwide. Many novel materials or methods to prevent HAB have not yet been employed except for clay dispersion, in which can the resulting sedimentation on the seafloor can also cause alteration in marine ecology or secondary environmental pollution. In the current study, we investigated that antimicrobial peptide have a potential in controlling HAB without cytotoxicity to harmless marine organisms. Here, antimicrobial peptides are proposed as new algicidal compounds in combating HAB cells. HPA3 and HPA3NT3 peptides which exert potent antimicrobial activity via pore forming action in plasma membrane showed that HPA3NT3 reduced the motility of algal cells, disrupted their plasma membrane, and induced the efflux of intracellular components. Against raphidoflagellate such as Heterosigma akashiwo, Chattonella sp., and C. marina, it displayed a rapid lysing action in cell membranes at 1~4 µM within 2 min. Comparatively, its lysing effects occurred at 8 µM within 1 h in dinoflagellate such as Cochlodium polykrikoides, Prorocentrum micans, and P. minimum. Moreover, its lysing action induced the lysis of chloroplasts and loss of chlorophyll a. In the contrary, this peptide was not effective against Skeletonema costatum, harmless algal cell, even at 256 µM, moreover, it killed only H. akashiwo or C. marina in co-cultivation with S. costatum, indicating to its selective algicidal activity between harmful and harmless algal cells. The peptide was non-hemolytic against red blood cells of Sebastes schlegeli, the black rockfish, at 120 µM. HAB cells were quickly and selectively lysed following treatment of antimicrobial peptides without cytotoxicity to harmless marine organisms. Thus, the antibiotic peptides examined in our study appear to have much potential in effectively controlling HAB with minimal impact on marine

  10. Microbial players involved in the decline of filamentous and colonial cyanobacterial blooms with a focus on fungal parasitism.

    Science.gov (United States)

    Gerphagnon, Mélanie; Macarthur, Deborah J; Latour, Delphine; Gachon, Claire M M; Van Ogtrop, Floris; Gleason, Frank H; Sime-Ngando, Télesphore

    2015-08-01

    In the forthcoming decades, it is widely believed that the dominance of colonial and filamentous bloom-forming cyanobacteria (e.g. Microcystis, Planktothrix, Anabaena and Cylindrospermopsis) will increase in freshwater systems as a combined result of anthropogenic nutrient input into freshwater bodies and climate change. While the physicochemical parameters controlling bloom dynamics are well known, the role of biotic factors remains comparatively poorly studied. Morphology and toxicity often - but not always - limit the availability of cyanobacteria to filter feeding zooplankton (e.g. cladocerans). Filamentous and colonial cyanobacteria are widely regarded as trophic dead-ends mostly inedible for zooplankton, but substantial evidence shows that some grazers (e.g. copepods) can bypass this size constraint by breaking down filaments, making the bloom biomass available to other zooplankton species. A wide range of algicidal bacteria (mostly from the Alcaligenes, Flavobacterium/Cytophaga group and Pseudomonas) and viruses (Podoviridae, Siphoviridae and Myoviridae) may also contribute to bloom control, via their lytic activity underpinned by a diverse array of mechanisms. Fungal parasitism by the Chytridiomycota remains the least studied. While each of these biotic factors has traditionally been studied in isolation, emerging research consistently point to complex interwoven interactions between biotic and environmental factors. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

  11. Biomass, production, and control of heterotrophic bacterioplankton during a late phytoplankton bloom in the Amundsen Sea Polynya, Antarctica

    Science.gov (United States)

    Hyun, Jung-Ho; Kim, Sung-Han; Yang, Eun Jin; Choi, Ayeon; Lee, Sang Hoon

    2016-01-01

    We investigated the heterotrophic bacterial biomass and production in February 2012, in four habitats (a polynya, sea-ice zone, ice shelf, and the open sea) in the Amundsen Sea to determine the spatial distribution, controlling factors, and ecological role of the bacteria during a late phytoplankton bloom by Phaeocystis antarctica. Bacterial abundance (BA) and production (BP) were highest at the center of the polynya, and both were significantly correlated with phytoplankton biomass. BP accounted for average 17% of the organic carbon produced by phytoplankton primary production (PP), which is higher than the average BP:PP ratio reported in most open ocean. The abundance of heterotrophic nanoflagellates (HNF) was correlated with the BA, and the average bacteria:HNF ratio (260) was lower than the values reported in most marine environments (400-1000), including the Ross Sea Polynya (800). Evidence for a tight coupling of bacteria and phytoplankton activities on the one hand and intense HNF grazing on bacteria on the other could be found in the high BP:PP and low bacteria:HNF ratios, respectively. Interestingly, these data were accompanied by low particulate carbon export fluxes measured during the late Phaeocystis bloom. Together, these results indicated that the microbial loop plays a significant role in the biogeochemical carbon cycle and food web processes in the Amundsen Sea Polynya.

  12. Harmful algal blooms of the Southern Benguela current: A review ...

    African Journals Online (AJOL)

    Harmful algal blooms of the Southern Benguela current: A review and appraisal of monitoring from 1989 to 1997. ... The Benguela upwelling system is subjected to blooms of harmful and toxic algae, the incidence and consequences of which are documented here. Red tides are common and usually attributed to members of ...

  13. WATER BLOOM OF BLUEGREEN ALGE IN CARP FISHPOUNDS

    Directory of Open Access Journals (Sweden)

    Melita Mihaljević

    1996-03-01

    Full Text Available The massive development of bluegreen algae (Cyanophyta/Cyanobacteria, the so--called water bloom, is a frequent phenomenon in fishpond ecosystems. This study analyses water bloom development in three carp fishponds owned by a fishbreeding company at Donji Miholjac (Croatia, where one-year-old carps (Cyprinus carpio , were bred in defferent fishstock densities. Analyses of physicallychemical properties of water and phytoplankton biomass were per- formed in fortnight intervals from May till October, 1992. In all there investigated fishponds the water bloom of bluegreen algae developed, but at a different time and showing a different qualitative composition. In the fishpond with fishstock density of 250 kg/ha water bloom consisted of the species Aphanizomenon flos-aquae, and the biggest biomass (131.92 mg/I was found in August. In the fishpond with fishstock density of 437 kg/ha a water bloom consisting of species from the genues Anabaena and species Aphanizomenon flos-aquae developed at the end of July. In the fishpond with the so--called intensive breeding (fishstock density of 750 kg/ha water bloom of the species Microcystis aeruginosa developed as late as September. The beginning of water bloom development was caused by the low value (lower than 7 of the ratio between the quantities of total phosphorus and total nitrogen. However, the qualitative composition of water bloom was influenced by one-year-old carp fingerlings density.

  14. Use of Bloom's Taxonomy in Developing Reading Comprehension Specifications

    Science.gov (United States)

    Luebke, Stephen; Lorie, James

    2013-01-01

    This article is a brief account of the use of Bloom's Taxonomy of Educational Objectives (Bloom, Engelhart, Furst, Hill, & Krathwohl, 1956) by staff of the Law School Admission Council in the 1990 development of redesigned specifications for the Reading Comprehension section of the Law School Admission Test. Summary item statistics for the…

  15. The Evolution of Educational Objectives: Bloom's Taxonomy and beyond

    Science.gov (United States)

    Fallahi, Carolyn R.; LaMonaca, Frank H., Jr.

    2009-01-01

    It is crucial for teachers to communicate effectively about educational objectives to students, colleagues, and others in education. In 1956, Bloom developed a cognitive learning taxonomy to enhance communication between college examiners. The Bloom taxonomy consists of 6 hierarchical levels of learning (knowledge, comprehension, application,…

  16. Subsurface phytoplankton blooms fuel pelagic production in the North Sea

    DEFF Research Database (Denmark)

    Richardson, Kathrine; Visser, Andre; Pedersen, Flemming

    2000-01-01

    convincingly that energy fixed during the spring bloom is fueling the pelagic production occurring during summer months. We argue here that periodic phytoplankton blooms are occurring during the summer in the North Sea at depths of >25 m and that the accumulated new production [sensu (Dugdale and Goering...

  17. Salmon mortalities associated with a bloom of Alexandrium ...

    African Journals Online (AJOL)

    Blue mussels Mytilus edulis analysed from areas affected by the bloom reached levels of 18 000ìg STX equivalents 100g–1 of tissue. As a result of the salmon mortalities, a project was initiated to establish a monitoring approach for harmful algal blooms to provide an early warning of potential events and to act as a tool for ...

  18. Autophagic clearance of bacterial pathogens: molecular recognition of intracellular microorganisms.

    Science.gov (United States)

    Pareja, Maria Eugenia Mansilla; Colombo, Maria I

    2013-01-01

    Autophagy is involved in several physiological and pathological processes. One of the key roles of the autophagic pathway is to participate in the first line of defense against the invasion of pathogens, as part of the innate immune response. Targeting of intracellular bacteria by the autophagic machinery, either in the cytoplasm or within vacuolar compartments, helps to control bacterial proliferation in the host cell, controlling also the spreading of the infection. In this review we will describe the means used by diverse bacterial pathogens to survive intracellularly and how they are recognized by the autophagic molecular machinery, as well as the mechanisms used to avoid autophagic clearance.

  19. Ocean fertilization experiments may initiate a large scale phytoplankton bloom

    Science.gov (United States)

    Neufeld, Zoltán; Haynes, Peter H.; Garçon, Véronique; Sudre, Joël

    2002-06-01

    Oceanic plankton plays an important role in the marine food chain and through its significant contribution to the global carbon cycle can also influence the climate. Plankton bloom is a sudden rapid increase of the population. It occurs naturally in the North Atlantic as a result of seasonal changes. Ocean fertilization experiments have shown that supply of iron, an important trace element, can trigger a phytoplankton bloom in oceanic regions with low natural phytoplankton density. Here we use a simple mathematical model of the combined effects of stirring by ocean eddies and plankton evolution to consider the impact of a transient local perturbation, e.g. in the form of iron enrichment as in recent `ocean fertilization' experiments. The model not only explains aspects of the bloom observed in such experiments but predicts the unexpected outcome of a large scale bloom that in its extent could be comparable to the spring bloom in the North Atlantic.

  20. Deep-Learning-Based Approach for Prediction of Algal Blooms

    Directory of Open Access Journals (Sweden)

    Feng Zhang

    2016-10-01

    Full Text Available Algal blooms have recently become a critical global environmental concern which might put economic development and sustainability at risk. However, the accurate prediction of algal blooms remains a challenging scientific problem. In this study, a novel prediction approach for algal blooms based on deep learning is presented—a powerful tool to represent and predict highly dynamic and complex phenomena. The proposed approach constructs a five-layered model to extract detailed relationships between the density of phytoplankton cells and various environmental parameters. The algal blooms can be predicted by the phytoplankton density obtained from the output layer. A case study is conducted in coastal waters of East China using both our model and a traditional back-propagation neural network for comparison. The results show that the deep-learning-based model yields better generalization and greater accuracy in predicting algal blooms than a traditional shallow neural network does.

  1. Characterization of Intracellular and Extracellular Saxitoxin Levels in Both Field and Cultured Alexandrium spp. Samples from Sequim Bay, Washington

    Directory of Open Access Journals (Sweden)

    Vera L. Trainer

    2008-05-01

    Full Text Available Traditionally, harmful algal bloom studies have primarily focused on quantifying toxin levels contained within the phytoplankton cells of interest. In the case of paralytic shellfish poisoning toxins (PSTs, intracellular toxin levels and the effects of dietary consumption of toxic cells by planktivores have been well documented. However, little information is available regarding the levels of extracellular PSTs that may leak or be released into seawater from toxic cells during blooms. In order to fully evaluate the risks of harmful algal bloom toxins in the marine food web, it is necessary to understand all potential routes of exposure. In the present study, extracellular and intracellular PST levels were measured in field seawater samples (collected weekly from June to October 2004- 2007 and in Alexandrium spp. culture samples isolated from Sequim Bay, Washington. Measurable levels of intra- and extra-cellular toxins were detected in both field and culture samples via receptor binding assay (RBA and an enzyme-linked immunosorbent assay (ELISA. Characterization of the PST toxin profile in the Sequim Bay isolates by preMar. column oxidation and HPLC-fluorescence detection revealed that gonyautoxin 1 and 4 made up 65 ± 9.7 % of the total PSTs present. Collectively, these data confirm that extracellular PSTs are present during blooms of Alexandrium spp. in the Sequim Bay region.

  2. Intracellular Cadmium Isotope Fractionation

    Science.gov (United States)

    Horner, T. J.; Lee, R. B.; Henderson, G. M.; Rickaby, R. E.

    2011-12-01

    Recent stable isotope studies into the biological utilization of transition metals (e.g. Cu, Fe, Zn, Cd) suggest several stepwise cellular processes can fractionate isotopes in both culture and nature. However, the determination of fractionation factors is often unsatisfactory, as significant variability can exist - even between different organisms with the same cellular functions. Thus, it has not been possible to adequately understand the source and mechanisms of metal isotopic fractionation. In order to address this problem, we investigated the biological fractionation of Cd isotopes within genetically-modified bacteria (E. coli). There is currently only one known biological use or requirement of Cd, a Cd/Zn carbonic anhydrase (CdCA, from the marine diatom T. weissfloggii), which we introduce into the E. coli genome. We have also developed a cleaning procedure that allows for the treating of bacteria so as to study the isotopic composition of different cellular components. We find that whole cells always exhibit a preference for uptake of the lighter isotopes of Cd. Notably, whole cells appear to have a similar Cd isotopic composition regardless of the expression of CdCA within the E. coli. However, isotopic fractionation can occur within the genetically modified E. coli during Cd use, such that Cd bound in CdCA can display a distinct isotopic composition compared to the cell as a whole. Thus, the externally observed fractionation is independent of the internal uses of Cd, with the largest Cd isotope fractionation occurring during cross-membrane transport. A general implication of these experiments is that trace metal isotopic fractionation most likely reflects metal transport into biological cells (either actively or passively), rather than relating to expression of specific physiological function and genetic expression of different metalloenzymes.

  3. Heterosigma bloom and associated fish kill

    Science.gov (United States)

    Hershberger, P.K.; Rensel, J.E.; Postel, J.R.; Taub, F.B.

    1997-01-01

    A bloom of the harmful marine phytoplankton, Heterosigma carterae occurred in upper Case Inlet, south Puget Sound, Washington in late September, 1994, correlating with the presence of at least 35 dead salmon. This marks the first time that this alga has been closely correlated with a wild fish kill; in the past it was thought to be associated with kills of penned fish at fish farms only. We were informed of the presence of a possible harmful algal bloom and dead salinois Ilear the town of Allyn on 27 September and a team was formed to investigate. We arrived at the Allyn waterfront at 17:30 hours the same day. Prior to our arrival, state agency personnel walked approximatcly two miles of shoreline from the powerlines north of the dock, to the mouth of Sherwood Creek and conducted the only official count of dead fish present along the shore consisting of 12 coho salmon (Oncorhynchus kisutch), 11 chum salmon (Oncorhynchus keta), 12 chinook salmon (Oncorhynchus tschawytscha), one flat fish, and one sculpin on the morning of 9/27. Since previous harmful blooms of Heterosigma have resultedin the majority of net penreared salmon sinking to the bottom of pens, and only approximately two miles of shoreline were sampled, it is suspected that many more exposed fish may have succumbed than were counted. Witnesses who explored the east side of the bay reported seeing many dead salmon there as well, but no counts were made. State agency personnel who observed the fish kill reported seeing “dying fish coming to the beach, gulping at the surface, trying to get out of the water” Scavengers were seen consuming the salmon carcasses; these included two harbor seals, a house cat, and Hymenopteran insects. None suffered any noticeable acute ill effects. Although precise cause of death has not been ascertained, visual inspection of the reproductive organs from a deceased male chum salmon found on the shore at Allyn confirmed that the fish was not yet reproductively mature and

  4. Harmful Algal Blooms and Public Health.

    Science.gov (United States)

    Grattan, Lynn M; Holobaugh, Sailor; Morris, J Glenn

    2016-07-01

    The five most commonly recognized Harmful Algal Bloom related illnesses include Ciguatera poisoning, Paralytic Shellfish poisoning, Neurotoxin Shellfish poisoning, Diarrheic Shellfish Poisoning and Amnesic Shellfish poisoning. Although they are each the product of different toxins, toxin assemblages or HAB precursors these clinical syndromes have much in common. Exposure occurs through the consumption of fish or shellfish; routine clinical tests are not available for diagnosis; there is no known antidote for exposure; and the risk of these illnesses can negatively impact local fishing and tourism industries. Thus, illness prevention is of paramount importance to minimize human and public health risks. To accomplish this, close communication and collaboration is needed among HAB scientists, public health researchers and local, state and tribal health departments at academic, community outreach, and policy levels.

  5. Microcystin in cyanobacterial blooms in a Chilean lake.

    Science.gov (United States)

    Campos, V; Cantarero, S; Urrutia, H; Heinze, R; Wirsing, B; Neumann, U; Weckesser, J

    1999-05-01

    Cyanobacterial blooms dominated by Microcystis sp. occurred in lake Rocuant ("marisma", near Concepción/Chile) in February 1995 and 1996. In the bloom samples collected in both years the hepatotoxin microcystin was detected by RP-HPLC in both samples and in the sample of 1995 also by a toxicity assay using primary rat hepatocytes. In the bloom of 1995, the microcystin content of the dry bloom biomass was determined to be 130 micrograms/g on the basis of the RP-HPLC peak area and 800 micrograms/g on the basis of the rat hepatotoxicity assay, respectively. In the bloom of 1996, RP-HPLC analysis revealed a microcystin content of 8.13 micrograms/g bloom material dry weight. In this year no hepatotoxicity was measured using a concentration range up to 0.8 mg (d. w.) of bloom material per ml in the rat hepatotoxicity assay. This is the first report on the detection of microcystins in Chilean water bodies.

  6. Pelagic microbial heterotrophy in response to a highly productive bloom of Phaeocystis antarctica in the Amundsen Sea Polynya, Antarctica

    Directory of Open Access Journals (Sweden)

    C.M. Williams

    2016-04-01

    Full Text Available Abstract Heterotrophic bacteria play a key role in marine carbon cycling, and understanding their activities in polar systems is important for considering climate change impacts there. One goal of the ASPIRE project was to examine the relationship between the phytoplankton bloom and bacterial heterotrophy in the Amundsen Sea Polynya (ASP. Bacterial abundance, production (BP, respiration, growth efficiency, and extracellular enzyme activity (EEA were compared to nutrient and organic matter inventories, chlorophyll a (Chl a, viral and microzooplankton abundance, and net primary production (NPP. Bacterial production and respiration clearly responded (0.04–4.0 and 10–53 µg C L−1 d−1, respectively to the buildup of a massive Phaeocystis antarctica bloom (Chl a: 0.2–22 µg L−1, with highest rates observed in the central polynya where Chl a and particulate organic carbon (POC were greatest. The highest BP rates exceeded those reported for the Ross Sea or any other Antarctic coastal system, yet the BP:NPP ratio (2.1–9.4% was relatively low. Bacterial respiration was also high, and growth efficiency (2–27%; median = 10% was similar to oligotrophic systems. Thus, the integrated bacterial carbon demand (0.8–2.8 g C m−2 d−1 was a high fraction (25–128%; median = 43% of NPP during bloom development. During peak bloom, activity was particle-associated: BP and EEA correlated well with POC, and size fractionation experiments showed that the larger size fraction (> 3 µm accounted for a majority (∼ 75% of the BP. The community was psychrophilic, with a 5x reduction in BP when warmed to 20°C. In deeper waters, respiration remained relatively high, likely fueled by the significant downward particle flux in the region. A highly active, particle-associated, heterotrophic microbial community clearly responded to the extraordinary phytoplankton bloom in the ASP, likely limiting biological pump efficiency during the early season.

  7. Aerial Images and Convolutional Neural Network for Cotton Bloom Detection

    Directory of Open Access Journals (Sweden)

    Rui Xu

    2018-02-01

    Full Text Available Monitoring flower development can provide useful information for production management, estimating yield and selecting specific genotypes of crops. The main goal of this study was to develop a methodology to detect and count cotton flowers, or blooms, using color images acquired by an unmanned aerial system. The aerial images were collected from two test fields in 4 days. A convolutional neural network (CNN was designed and trained to detect cotton blooms in raw images, and their 3D locations were calculated using the dense point cloud constructed from the aerial images with the structure from motion method. The quality of the dense point cloud was analyzed and plots with poor quality were excluded from data analysis. A constrained clustering algorithm was developed to register the same bloom detected from different images based on the 3D location of the bloom. The accuracy and incompleteness of the dense point cloud were analyzed because they affected the accuracy of the 3D location of the blooms and thus the accuracy of the bloom registration result. The constrained clustering algorithm was validated using simulated data, showing good efficiency and accuracy. The bloom count from the proposed method was comparable with the number counted manually with an error of −4 to 3 blooms for the field with a single plant per plot. However, more plots were underestimated in the field with multiple plants per plot due to hidden blooms that were not captured by the aerial images. The proposed methodology provides a high-throughput method to continuously monitor the flowering progress of cotton.

  8. Floating Algae Blooms in the East China Sea

    Science.gov (United States)

    Qi, Lin; Hu, Chuanmin; Wang, Mengqiu; Shang, Shaoling; Wilson, Cara

    2017-11-01

    A floating algae bloom in the East China Sea was observed in Moderate Resolution Imaging Spectroradiometer (MODIS) imagery in May 2017. Using satellite imagery from MODIS, Visible Infrared Imaging Radiometer Suite, Geostationary Ocean Color Imager, and Ocean Land Imager, and combined with numerical particle tracing experiments and laboratory experiments, we examined the history of this bloom as well as similar blooms in previous years and attempted to trace the bloom source and identify the algae type. Results suggest that one bloom origin is offshore Zhejiang coast where algae slicks have appeared in satellite imagery almost every February-March since 2012. Following the Kuroshio Current and Taiwan Warm Current, these "initial" algae slicks are first transported to the northeast to reach South Korea (Jeju Island) and Japan coastal waters (up to 135°E) by early April 2017, and then transported to the northwest to enter the Yellow Sea by the end of April. The transport pathway covers an area known to be rich in Sargassum horneri, and spectral analysis suggests that most of the algae slicks may contain large amount of S. horneri. The bloom covers a water area of 160,000 km2 with pure algae coverage of 530 km2, which exceeds the size of most Ulva blooms that occur every May-July in the Yellow Sea. While blooms of smaller size also occurred in previous years and especially in 2015, the 2017 bloom is hypothesized to be a result of record-high water temperature, increased light availability, and continuous expansion of Porphyra aquaculture along the East China Sea coast.

  9. Purine Biosynthesis Metabolically Constrains Intracellular Survival of Uropathogenic Escherichia coli

    Science.gov (United States)

    Shaffer, Carrie L.; Zhang, Ellisa W.; Dudley, Anne G.; Dixon, Beverly R. E. A.; Guckes, Kirsten R.; Breland, Erin J.; Floyd, Kyle A.; Casella, Daniel P.; Algood, Holly M. Scott; Clayton, Douglass B.

    2016-01-01

    ABSTRACT The ability to de novo synthesize purines has been associated with the intracellular survival of multiple bacterial pathogens. Uropathogenic Escherichia coli (UPEC), the predominant cause of urinary tract infections, undergoes a transient intracellular lifestyle during which bacteria clonally expand into multicellular bacterial communities within the cytoplasm of bladder epithelial cells. Here, we characterized the contribution of the conserved de novo purine biosynthesis-associated locus cvpA-purF to UPEC pathogenesis. Deletion of cvpA-purF, or of purF alone, abolished de novo purine biosynthesis but did not impact bacterial adherence properties in vitro or in the bladder lumen. However, upon internalization by bladder epithelial cells, UPEC deficient in de novo purine biosynthesis was unable to expand into intracytoplasmic bacterial communities over time, unless it was extrachromosomally complemented. These findings indicate that UPEC is deprived of purine nucleotides within the intracellular niche and relies on de novo purine synthesis to meet this metabolic requirement. PMID:27795353

  10. Structural Diversity of Bacterial Communities Associated with Bloom-Forming Freshwater Cyanobacteria Differs According to the Cyanobacterial Genus.

    Directory of Open Access Journals (Sweden)

    Imen Louati

    Full Text Available The factors and processes driving cyanobacterial blooms in eutrophic freshwater ecosystems have been extensively studied in the past decade. A growing number of these studies concern the direct or indirect interactions between cyanobacteria and heterotrophic bacteria. The presence of bacteria that are directly attached or immediately adjacent to cyanobacterial cells suggests that intense nutrient exchanges occur between these microorganisms. In order to determine if there is a specific association between cyanobacteria and bacteria, we compared the bacterial community composition during two cyanobacteria blooms of Anabaena (filamentous and N2-fixing and Microcystis (colonial and non-N2 fixing that occurred successively within the same lake. Using high-throughput sequencing, we revealed a clear distinction between associated and free-living communities and between cyanobacterial genera. The interactions between cyanobacteria and bacteria appeared to be based on dissolved organic matter degradation and on N recycling, both for N2-fixing and non N2-fixing cyanobacteria. Thus, the genus and potentially the species of cyanobacteria and its metabolic capacities appeared to select for the bacterial community in the phycosphere.

  11. Winter−spring transition in the subarctic Atlantic: microbial response to deep mixing and pre-bloom production

    DEFF Research Database (Denmark)

    Paulsen, Maria Lund; Riisgaard, Karen; Thingstad, T. Frede

    2015-01-01

    In temperate, subpolar and polar marine systems, the classical perception is that diatoms initiate the spring bloom and thereby mark the beginning of the productive season. Contrary to this view, we document an active microbial food web dominated by pico- and nanoplankton prior to the diatom bloom......, a period with excess nutrients and deep convection of the water column. During repeated visits to stations in the deep Iceland and Norwegian basins and the shallow Shetland Shelf (26 March to 29 April 2012), we investigated the succession and dynamics of photo - synthetic and heterotrophic microorganisms....... We observed that the early phytoplankton production was followed by a decrease in the carbon:nitrogen ratio of the dissolved organic matter in the deep mixed stations, an increase in heterotrophic prokaryote (bacteria) abundance and activity (indicated by the high nucleic acid:low nucleic acid...

  12. Qualitative importance of the microbial loop and plankton community structure in a eutropic lake during a bloom of Cyanobacteria

    DEFF Research Database (Denmark)

    Christoffersen, K.

    1990-01-01

    smaller than 20 um replaced Aphanizornenon after the culmination of cyanobacteria. Bacterial net production peaked shortly after the culmination of the bloom (510 ug C liter- 1 d-') and decreased thereafter to a level of approximately 124 gg C liter-' d -~. Phytoplankton extracellular release of organic......Plankton community structure and m~or pools and fluxes of carbon were observed before and after culmination of a bloom of cyanobacteria in eutrophic Frederiksborg Slotsso, Denmark. Biomass changes of heterotrophic nanoflagellates, ciliates, microzooplankton (50 to 140 urn), and macrozooplankton...... (larger than 140 Urn) were compared to phytoplankton and bacterial production as well as micro- and macrozooplankton ingestion rates of phytoplankton and bacteria. The carbon budget was used as a means to examine causal relationships in the plankton community. Phytoplankton biomass decreased and algae...

  13. Effects of fertilizers used in agricultural fields on algal blooms

    DEFF Research Database (Denmark)

    Chakraborty, Subhendu; Tiwari, P. K.; Sasmal, S. K.

    2017-01-01

    The increasing occurrence of algal blooms and their negative ecological impacts have led to intensified monitoring activities. This needs the proper identification of the most responsible factor/factors for the bloom formation. However, in natural systems, algal blooms result from a combination...... of factors and from observation it is difficult to identify the most important one. In the present paper, using a mathematical model we compare the effects of three human induced factors (fertilizer input in agricultural field, eutrophication due to other sources than fertilizers, and overfishing...

  14. Identification of bloom date QTLs and haplotype analysis in tetraploid sour cherry (Prunus cerasus)

    NARCIS (Netherlands)

    Cai, Lichun; Stegmeir, Travis; Sebolt, Audrey; Zheng, Chaozhi; Bink, Marco C.A.M.; Iezzoni, Amy

    2018-01-01

    Bloom date is an important production trait in sour cherry (Prunus cerasus L.) as the risk of crop loss to floral freeze injury increases with early bloom time. Knowledge of the major loci controlling bloom date would enable breeders to design crosses and select seedlings with late bloom date. As

  15. The intracellular pharmacokinetics of terminally capped peptides.

    NARCIS (Netherlands)

    Ruttekolk, I.R.R.; Witsenburg, J.J.; Glauner, H.B.; Bovee-Geurts, P.H.M.; Ferro, E.S.; Verdurmen, W.P.R.; Brock, R.E.

    2012-01-01

    With significant progress in delivery technologies, peptides and peptidomimetics are receiving increasing attention as potential therapeutics also for intracellular applications. However, analyses of the intracellular behavior of peptides are a challenge; therefore, knowledge on the intracellular

  16. Phytoplankton bloom dynamics in coastal ecosystems: A review with some general lessons from sustained investigation of San Francisco Bay, California

    Science.gov (United States)

    Cloern, James E.

    1996-05-01

    Phytoplankton blooms are prominent features of biological variability in shallow coastal ecosystems such as estuaries, lagoons, bays, and tidal rivers. Long-term observation and research in San Francisco Bay illustrates some patterns of phytoplankton spatial and temporal variability and the underlying mechanisms of this variability. Blooms are events of rapid production and accumulation of phytoplankton biomass that are usually responses to changing physical forcings originating in the coastal ocean (e.g., tides), the atmosphere (wind), or on the land surface (precipitation and river runoff). These physical forcings have different timescales of variability, so algal blooms can be short-term episodic events, recurrent seasonal phenomena, or rare events associated with exceptional climatic or hydrologic conditions. The biogeochemical role of phytoplankton primary production is to transform and incorporate reactive inorganic elements into organic forms, and these transformations are rapid and lead to measurable geochemical change during blooms. Examples include the depletion of inorganic nutrients (N, P, Si), supersaturation of oxygen and removal of carbon dioxide, shifts in the isotopic composition of reactive elements (C, N), production of climatically active trace gases (methyl bromide, dimethylsulfide), changes in the chemical form and toxicity of trace metals (As, Cd, Ni, Zn), changes in the biochemical composition and reactivity of the suspended particulate matter, and synthesis of organic matter required for the reproduction and growth of heterotrophs, including bacteria, zooplankton, and benthic consumer animals. Some classes of phytoplankton play special roles in the cycling of elements or synthesis of specific organic molecules, but we have only rudimentary understanding of the forces that select for and promote blooms of these species. Mounting evidence suggests that the natural cycles of bloom variability are being altered on a global scale by human

  17. Pepsin homologues in bacteria

    Directory of Open Access Journals (Sweden)

    Bateman Alex

    2009-09-01

    Full Text Available Abstract Background Peptidase family A1, to which pepsin belongs, had been assumed to be restricted to eukaryotes. The tertiary structure of pepsin shows two lobes with similar folds and it has been suggested that the gene has arisen from an ancient duplication and fusion event. The only sequence similarity between the lobes is restricted to the motif around the active site aspartate and a hydrophobic-hydrophobic-Gly motif. Together, these contribute to an essential structural feature known as a psi-loop. There is one such psi-loop in each lobe, and so each lobe presents an active Asp. The human immunodeficiency virus peptidase, retropepsin, from peptidase family A2 also has a similar fold but consists of one lobe only and has to dimerize to be active. All known members of family A1 show the bilobed structure, but it is unclear if the ancestor of family A1 was similar to an A2 peptidase, or if the ancestral retropepsin was derived from a half-pepsin gene. The presence of a pepsin homologue in a prokaryote might give insights into the evolution of the pepsin family. Results Homologues of the aspartic peptidase pepsin have been found in the completed genomic sequences from seven species of bacteria. The bacterial homologues, unlike those from eukaryotes, do not possess signal peptides, and would therefore be intracellular acting at neutral pH. The bacterial homologues have Thr218 replaced by Asp, a change which in renin has been shown to confer activity at neutral pH. No pepsin homologues could be detected in any archaean genome. Conclusion The peptidase family A1 is found in some species of bacteria as well as eukaryotes. The bacterial homologues fall into two groups, one from oceanic bacteria and one from plant symbionts. The bacterial homologues are all predicted to be intracellular proteins, unlike the eukaryotic enzymes. The bacterial homologues are bilobed like pepsin, implying that if no horizontal gene transfer has occurred the duplication

  18. Intracellular Nitrate of Marine Diatoms as a Driver of Anaerobic Nitrogen Cycling in Sinking Aggregates

    Directory of Open Access Journals (Sweden)

    Anja Kamp

    2016-11-01

    Full Text Available Diatom-bacteria aggregates are key for the vertical transport of organic carbon in the ocean. Sinking aggregates also represent pelagic microniches with intensified microbial activity, oxygen depletion in the center, and anaerobic nitrogen cycling. Since some of the aggregate-forming diatom species store nitrate intracellularly, we explored the fate of intracellular nitrate and its availability for microbial metabolism within anoxic diatom-bacteria aggregates. The ubiquitous nitrate-storing diatom Skeletonema marinoi was studied as both axenic cultures and laboratory-produced diatom-bacteria aggregates. Stable 15N isotope incubations under dark and anoxic conditions revealed that axenic S. marinoi is able to reduce intracellular nitrate to ammonium that is immediately excreted by the cells. When exposed to a light:dark cycle and oxic conditions, S. marinoi stored nitrate intracellularly in concentrations > 60 mmol L-1 both as free-living cells and associated to aggregates. Intracellular nitrate concentrations exceeded extracellular concentrations by three orders of magnitude. Intracellular nitrate was used up within 2-3 days after shifting diatom-bacteria aggregates to dark and anoxic conditions. Thirty-one percent of the diatom-derived nitrate was converted to nitrogen gas, indicating that a substantial fraction of the intracellular nitrate pool of S. marinoi becomes available to the aggregate-associated bacterial community. Only 5% of the intracellular nitrate was reduced to ammonium, while 59% was recovered as nitrite. Hence, aggregate-associated diatoms accumulate nitrate from the surrounding water and sustain complex nitrogen transformations, including loss of fixed nitrogen, in anoxic, pelagic microniches. Additionally, it may be expected that intracellular nitrate not converted before the aggregates have settled onto the seafloor could fuel benthic nitrogen transformations.

  19. Intracellular Nitrate of Marine Diatoms as a Driver of Anaerobic Nitrogen Cycling in Sinking Aggregates

    Science.gov (United States)

    Kamp, Anja; Stief, Peter; Bristow, Laura A.; Thamdrup, Bo; Glud, Ronnie N.

    2016-01-01

    Diatom-bacteria aggregates are key for the vertical transport of organic carbon in the ocean. Sinking aggregates also represent pelagic microniches with intensified microbial activity, oxygen depletion in the center, and anaerobic nitrogen cycling. Since some of the aggregate-forming diatom species store nitrate intracellularly, we explored the fate of intracellular nitrate and its availability for microbial metabolism within anoxic diatom-bacteria aggregates. The ubiquitous nitrate-storing diatom Skeletonema marinoi was studied as both axenic cultures and laboratory-produced diatom-bacteria aggregates. Stable 15N isotope incubations under dark and anoxic conditions revealed that axenic S. marinoi is able to reduce intracellular nitrate to ammonium that is immediately excreted by the cells. When exposed to a light:dark cycle and oxic conditions, S. marinoi stored nitrate intracellularly in concentrations >60 mmol L-1 both as free-living cells and associated to aggregates. Intracellular nitrate concentrations exceeded extracellular concentrations by three orders of magnitude. Intracellular nitrate was used up within 2–3 days after shifting diatom-bacteria aggregates to dark and anoxic conditions. Thirty-one percent of the diatom-derived nitrate was converted to nitrogen gas, indicating that a substantial fraction of the intracellular nitrate pool of S. marinoi becomes available to the aggregate-associated bacterial community. Only 5% of the intracellular nitrate was reduced to ammonium, while 59% was recovered as nitrite. Hence, aggregate-associated diatoms accumulate nitrate from the surrounding water and sustain complex nitrogen transformations, including loss of fixed nitrogen, in anoxic, pelagic microniches. Additionally, it may be expected that intracellular nitrate not converted before the aggregates have settled onto the seafloor could fuel benthic nitrogen transformations. PMID:27847498

  20. Eddy-driven stratification initiates North Atlantic spring phytoplankton blooms.

    Science.gov (United States)

    Mahadevan, Amala; D'Asaro, Eric; Lee, Craig; Perry, Mary Jane

    2012-07-06

    Springtime phytoplankton blooms photosynthetically fix carbon and export it from the surface ocean at globally important rates. These blooms are triggered by increased light exposure of the phytoplankton due to both seasonal light increase and the development of a near-surface vertical density gradient (stratification) that inhibits vertical mixing of the phytoplankton. Classically and in current climate models, that stratification is ascribed to a springtime warming of the sea surface. Here, using observations from the subpolar North Atlantic and a three-dimensional biophysical model, we show that the initial stratification and resulting bloom are instead caused by eddy-driven slumping of the basin-scale north-south density gradient, resulting in a patchy bloom beginning 20 to 30 days earlier than would occur by warming.

  1. Nutrient control of cyanobacterial blooms in the Baltic Sea

    NARCIS (Netherlands)

    Stal, L.J.; Staal, M.J.; Villbrandt, M.

    1999-01-01

    Cyanobacterial blooms in the Baltic Sea were investigated with respect to growth Limitation and nitrogen fixation. The community was composed predominantly of Synechococcus spp., and large, heterocystous, nitrogen-fixing cyanobacteria (Aphanizomenon spp, and Nodularia spp.), that usually formed

  2. Enhancing blooming period and propagation coefficient of tulip ...

    African Journals Online (AJOL)

    Enhancing blooming period and propagation coefficient of tulip (Tulipa gesneriana L.) using growth regulators. Ramesh Kumar, Nazeer Ahmed, Desh Beer Singh, Om Chand Sharma, Shiv Lal, Mohammad Muzamil Salmani ...

  3. Algal blooms: an emerging threat to seawater reverse osmosis desalination

    KAUST Repository

    Villacorte, Loreen O.

    2014-08-04

    Seawater reverse osmosis (SWRO) desalination technology has been rapidly growing in terms of installed capacity and global application over the last decade. An emerging threat to SWRO application is the seasonal proliferation of microscopic algae in seawater known as algal blooms. Such blooms have caused operational problems in SWRO plants due to clogging and poor effluent quality of the pre-treatment system which eventually forced the shutdown of various desalination plants to avoid irreversible fouling of downstream SWRO membranes. This article summarizes the current state of SWRO technology and the emerging threat of algal blooms to its application. It also highlights the importance of studying the algal bloom phenomena in the perspective of seawater desalination, so proper mitigation and preventive strategies can be developed in the near future. © 2014 © 2014 Balaban Desalination Publications. All rights reserved.

  4. Dust depositions leading to phytoplankton blooms in the Arabian sea.

    Digital Repository Service at National Institute of Oceanography (India)

    Banerjee, P.; PrasannaKumar, S.

    The authors thank the Director CSIR-NIO, Goa and Council of Scientific and Industrial Research, India for support. Dust depositions leading to phytoplankton blooms in the Arabian Sea Banerjee P.* and S. Prasanna Kumar *Physical Oceanography Division, CSIR...

  5. Cyanobacterial bloom detection based on coherence between ferrybox observations

    NARCIS (Netherlands)

    Groetsch, P.M.M.; Simis, S.G.H.; Eleveld, M.A.; Peters, S.W.M.

    2014-01-01

    Cyanobacterial bloom detection from flow-through optical sensors on ships-of-opportunity ('ferryboxes') is challenging in periods of strong stratification and due to varying cell physiology and phytoplankton community composition. Wavelet coherence analysis between ferrybox parameters (chlorophyll-

  6. Oxylipin production during a mesocosm bloom of Skeletonema marinoi

    DEFF Research Database (Denmark)

    Gerecht, Andrea; Carotenuto, Ylenia; Ianora, Adrianna

    2013-01-01

    suitable prey or to the limited exposure of the copepods to the oxylipins generated during the short bloom. Follow up laboratory studies showed that oxylipin composition changed both when the S. marinoi clone used for inoculation was grown in the laboratory and in comparison to the well-studied Adriatic...... clone of S. marinoi. These results highlight the necessity of quantitatively measuring oxylipin concentrations during diatom blooms at sea to be able to correctly evaluate their ecological significance....

  7. The paradox of algal blooms in oligotrophic waters

    Science.gov (United States)

    Sundareshwar, P. V.; Upadhyay, S.; Abessa, M. B.; Honomichl, S.; Berdanier, B.; Spaulding, S.; Sandvik, C.; Trennepohl, A.

    2010-12-01

    Nutrient inputs to streams and lakes, primarily from anthropogenic sources, lead to eutrophic conditions that favor algal blooms with undesirable consequences. In contrast, low nutrient or oligotrophic waters rarely support algal blooms; such ecosystems are typically lower in productivity. Since the mid-1980’s however, the diatom Didymosphenia geminata has dramatically expanded its range colonizing oligotrophic rivers worldwide with blooms appearing as thick benthic mats. This recent global occurrence of Didymosphenia geminata blooms in temperate rivers has been perplexing in its pace of spread and the paradoxical nature of the nuisance growths. The blooms occur primarily in oligotrophic flowing waters, where phosphorus (P) availability often limits primary production. We present a biogeochemical process by which D. geminata mats adsorb both P and iron (Fe) from flowing waters and make P available for cellular uptake. The adsorbed P becomes bioavailable through biogeochemical processes that occur within the mat. The biogeochemical processes observed here while well accepted in benthic systems are novel for algal blooms in lotic habits. Enzymatic and bacterial processes such as Fe and sulfate reduction can release the adsorbed P and increase its bioavailability, creating a positive feedback between total stalk biomass and nutrient availability. Stalk affinity for Fe, Fe-P biogeochemistry, and interaction between watershed processes and climatic setting explain the paradoxical blooms, and the recent global spread of this invasive aquatic species. At a broader scale the study also implies that such algal blooms in oligotrophic environments can fundamentally alter the retention and longitudinal transfer of important nutrients such as P in streams and rivers.

  8. Harmful algal bloom smart device application: using image analysis and machine learning techniques for early classification of harmful algal blooms (SETAC presentation)

    Science.gov (United States)

    Reports of toxic cyanobacterial blooms, also known as Harmful Algal Blooms (HABS) have increased drastically in recent years. HABS impact human health from causing mild allergies to liver damage and death. The Ecological Stewardship Institute (ESI) at Northern Kentucky Universi...

  9. Surveillance for Intracellular Antibody by Cytosolic Fc Receptor TRIM21

    Directory of Open Access Journals (Sweden)

    William A. McEwan

    2016-11-01

    Full Text Available TRIM21 has emerged as an atypical Fc receptor that is broadly conserved and widely expressed in the cytoplasm of mammalian cells. Viruses that traffic surface-bound antibodies into the cell during infection recruit TRIM21 via a high affinity interaction between Fc and TRIM21 PRYSPRY domain. Following binding of intracellular antibody, TRIM21 acts as both antiviral effector and sensor for innate immune signalling. These activities serve to reduce viral replication by orders of magnitude in vitro and contribute to host survival during in vivo infection. Neutralization occurs rapidly after detection and requires the activity of the ubiquitin-proteasome system. The microbial targets of this arm of intracellular immunity are still being identified: TRIM21 activity has been reported following infection by several non-enveloped viruses and intracellular bacteria. These findings extend the sphere of influence of antibodies to the intracellular domain and have broad implications for immunity. TRIM21 has been implicated in the chronic auto-immune condition systemic lupus erythematosus and is itself an auto-antigen in Sjögren’s syndrome. This review summarises our current understanding of TRIM21’s role as a cytosolic Fc receptor and briefly discusses pathological circumstances where intracellular antibodies have been described, or are hypothesized to occur, and may benefit from further investigations of the role of TRIM21.

  10. Host-directed antimicrobial drugs with broad-spectrum efficacy against intracellular bacterial pathogens.

    Science.gov (United States)

    Czyż, Daniel M; Potluri, Lakshmi-Prasad; Jain-Gupta, Neeta; Riley, Sean P; Martinez, Juan J; Steck, Theodore L; Crosson, Sean; Shuman, Howard A; Gabay, Joëlle E

    2014-07-29

    We sought a new approach to treating infections by intracellular bacteria, namely, by altering host cell functions that support their growth. We screened a library of 640 Food and Drug Administration (FDA)-approved compounds for agents that render THP-1 cells resistant to infection by four intracellular pathogens. We identified numerous drugs that are not antibiotics but were highly effective in inhibiting intracellular bacterial growth with limited toxicity to host cells. These compounds are likely to target three kinds of host functions: (i) G protein-coupled receptors, (ii) intracellular calcium signals, and (iii) membrane cholesterol distribution. The compounds that targeted G protein receptor signaling and calcium fluxes broadly inhibited Coxiella burnetii, Legionella pneumophila, Brucella abortus, and Rickettsia conorii, while those directed against cholesterol traffic strongly attenuated the intracellular growth of C. burnetii and L. pneumophila. These pathways probably support intracellular pathogen growth so that drugs that perturb them may be therapeutic candidates. Combining host- and pathogen-directed treatments is a strategy to decrease the emergence of drug-resistant intracellular bacterial pathogens. Importance: Although antibiotic treatment is often successful, it is becoming clear that alternatives to conventional pathogen-directed therapy must be developed in the face of increasing antibiotic resistance. Moreover, the costs and timing associated with the development of novel antimicrobials make repurposed FDA-approved drugs attractive host-targeted therapeutics. This paper describes a novel approach of identifying such host-targeted therapeutics against intracellular bacterial pathogens. We identified several FDA-approved drugs that inhibit the growth of intracellular bacteria, thereby implicating host intracellular pathways presumably utilized by bacteria during infection. Copyright © 2014 Czyż et al.

  11. Magnetic Bacteria.

    Science.gov (United States)

    Nelson, Jane Bray; Nelson, Jim

    1992-01-01

    Describes the history of Richard Blakemore's discovery of magnetotaxic organisms. Discusses possible reasons why the magnetic response in bacteria developed. Proposes research experiments integrating biology and physics in which students investigate problems using cultures of magnetotaxic organisms. (MDH)

  12. Big bacteria

    DEFF Research Database (Denmark)

    Schulz, HN; Jørgensen, BB

    2001-01-01

    A small number of prokaryotic species have a unique physiology or ecology related to their development of unusually large size. The biomass of bacteria varies over more than 10 orders of magnitude, from the 0.2 mum wide nanobacteria to the largest cells of the colorless sulfur bacteria......, Thiomargarita namibiensis, with a diameter of 750 mum. All bacteria, including those that swim around in the environment, obtain their food molecules by molecular diffusion. Only the fastest and largest swimmers known, Thiovulum majus, are able to significantly increase their food supply by motility...... and by actively creating an advective flow through the entire population. Diffusion limitation generally restricts the maximal size of prokaryotic cells and provides a selective advantage for mum-sized cells at the normally low substrate concentrations in the environment. The largest heterotrophic bacteria...

  13. Big bacteria

    DEFF Research Database (Denmark)

    Schulz, HN; Jørgensen, BB

    2001-01-01

    A small number of prokaryotic species have a unique physiology or ecology related to their development of unusually large size. The biomass of bacteria varies over more than 10 orders of magnitude, from the 0.2 mum wide nanobacteria to the largest cells of the colorless sulfur bacteria...... and by actively creating an advective flow through the entire population. Diffusion limitation generally restricts the maximal size of prokaryotic cells and provides a selective advantage for mum-sized cells at the normally low substrate concentrations in the environment. The largest heterotrophic bacteria......, the 80 x 600 mum large Epulopiscium sp. from the gut of tropical fish, are presumably living in a very nutrient-rich medium. Many large bacteria contain numerous inclusions in the cells that reduce the volume of active cytoplasm. The most striking examples of competitive advantage from large cell size...

  14. Effects of fertilizers used in agricultural fields on algal blooms

    Science.gov (United States)

    Chakraborty, Subhendu; Tiwari, P. K.; Sasmal, S. K.; Misra, A. K.; Chattopadhyay, Joydev

    2017-06-01

    The increasing occurrence of algal blooms and their negative ecological impacts have led to intensified monitoring activities. This needs the proper identification of the most responsible factor/factors for the bloom formation. However, in natural systems, algal blooms result from a combination of factors and from observation it is difficult to identify the most important one. In the present paper, using a mathematical model we compare the effects of three human induced factors (fertilizer input in agricultural field, eutrophication due to other sources than fertilizers, and overfishing) on the bloom dynamics and DO level. By applying a sophisticated sensitivity analysis technique, we found that the increasing use of fertilizers in agricultural field causes more rapid algal growth and decreases DO level much faster than eutrophication from other sources and overfishing. We also look at the mechanisms how fertilizer input rate affects the algal bloom dynamics and DO level. The model can be helpful for the policy makers in determining the influential factors responsible for the bloom formation.

  15. Unexpected winter phytoplankton blooms in the North Atlantic subpolar gyre

    Science.gov (United States)

    Lacour, L.; Ardyna, M.; Stec, K. F.; Claustre, H.; Prieur, L.; Poteau, A.; D'Alcala, M. Ribera; Iudicone, D.

    2017-11-01

    In mid- and high-latitude oceans, winter surface cooling and strong winds drive turbulent mixing that carries phytoplankton to depths of several hundred metres, well below the sunlit layer. This downward mixing, in combination with low solar radiation, drastically limits phytoplankton growth during the winter, especially that of the diatoms and other species that are involved in seeding the spring bloom. Here we present observational evidence for widespread winter phytoplankton blooms in a large part of the North Atlantic subpolar gyre from autonomous profiling floats equipped with biogeochemical sensors. These blooms were triggered by intermittent restratification of the mixed layer when mixed-layer eddies led to a horizontal transport of lighter water over denser layers. Combining a bio-optical index with complementary chemotaxonomic and modelling approaches, we show that these restratification events increase phytoplankton residence time in the sunlight zone, resulting in greater light interception and the emergence of winter blooms. Restratification also caused a phytoplankton community shift from pico- and nanophytoplankton to phototrophic diatoms. We conclude that transient winter blooms can maintain active diatom populations throughout the winter months, directly seeding the spring bloom and potentially making a significant contribution to over-winter carbon export.

  16. A quantitative model of intracellular growth of Legionella pneumophila in Acanthamoeba castellanii.

    Science.gov (United States)

    Moffat, J F; Tompkins, L S

    1992-01-01

    A model of intracellular growth for Legionella pneumophila in Acanthamoeba castellanii has been developed and provides a quantitative measure of survival and replication after entry. In this model, Acanthamoeba monolayers were incubated with bacteria in tissue culture plates under nutrient-limiting conditions. Gentamicin was used to kill extracellular bacteria following the period of incubation, and the number of intracellular bacteria was determined following lysis of amebae. Intracellular growth of virulent L. pneumophila and other wild-type Legionella species was observed when the assay was performed at 37 degrees C. At room temperature, none of the Legionella strains tested grew intracellularly, while an avirulent L. pneumophila strain was unable to replicate in this assay at either temperature. The effect of nutrient limitation on A. castellanii during the assay prevented multiplication of the amebae and increased the level of infection by Legionella spp. The level of infection of the amebae was directly proportional to the multiplicity of infection with bacteria; at an inoculum of 1.03 x 10(7) bacteria added to wells containing 1.10 x 10(5) amebae (multiplicity of infection of 100), approximately 4.4% of A. castellanii cells became infected. Cytochalasin D reduced the uptake of bacteria by the amebae primarily by causing amebae to lift off the culture dish, reducing the number of target hosts; methylamine also reduced the level of initial infection, yet neither inhibitor was able to prevent intracellular replication of Legionella spp. Consequently, once the bacteria entered the cell, only lowered temperature could restrict replication. This model of intracellular growth provides a one-step growth curve and should be useful to study the molecular basis of the host-parasite interaction. PMID:1729191

  17. Harmful algal bloom smart device application: using image analysis and machine learning techniques for early classification of harmful algal blooms

    Science.gov (United States)

    The Ecological Stewardship Institute at Northern Kentucky University and the U.S. Environmental Protection Agency are collaborating to optimize a harmful algal bloom detection algorithm that estimates the presence and count of cyanobacteria in freshwater systems by image analysis...

  18. Satellite monitoring of cyanobacterial harmful algal bloom ...

    Science.gov (United States)

    Cyanobacterial harmful algal blooms (cyanoHABs) cause extensive problems in lakes worldwide, including human and ecological health risks, anoxia and fish kills, and taste and odor problems. CyanoHABs are a particular concern because of their dense biomass and the risk of exposure to toxins in both recreational waters and drinking source waters. Successful cyanoHAB assessment by satellites may provide a first-line of defense indicator for human and ecological health protection. In this study, assessment methods were developed to determine the utility of satellite technology for detecting cyanoHAB occurrence frequency at locations of potential management interest. The European Space Agency's MEdium Resolution Imaging Spectrometer (MERIS) was evaluated to prepare for the equivalent Sentinel-3 Ocean and Land Colour Imager (OLCI) launched in 2016. Based on the 2012 National Lakes Assessment site evaluation guidelines and National Hydrography Dataset, there were 275,897 lakes and reservoirs greater than 1 hectare in the 48 U.S. states. Results from this evaluation show that 5.6 % of waterbodies were resolvable by satellites with 300 m single pixel resolution and 0.7 % of waterbodies were resolvable when a 3x3 pixel array was applied based on minimum Euclidian distance from shore. Satellite data was also spatially joined to US public water surface intake (PWSI) locations, where single pixel resolution resolved 57% of PWSI and a 3x3 pixel array resolved 33% of

  19. Evaluation of Harmful Algal Bloom Outreach Activities

    Directory of Open Access Journals (Sweden)

    Richard Weisman

    2007-12-01

    Full Text Available With an apparent increase of harmful algal blooms (HABs worldwide,healthcare providers, public health personnel and coastal managers are struggling toprovide scientifically-based appropriately-targeted HAB outreach and education. Since1998, the Florida Poison Information Center-Miami, with its 24 hour/365 day/year freeAquatic Toxins Hotline (1-888-232-8635 available in several languages, has received over 25,000 HAB-related calls. As part of HAB surveillance, all possible cases of HAB-relatedillness among callers are reported to the Florida Health Department. This pilot studyevaluated an automated call processing menu system that allows callers to access bilingualHAB information, and to speak directly with a trained Poison Information Specialist. Themajority (68% of callers reported satisfaction with the information, and many provided specific suggestions for improvement. This pilot study, the first known evaluation of use and satisfaction with HAB educational outreach materials, demonstrated that the automated system provided useful HAB-related information for the majority of callers, and decreased the routine informational call workload for the Poison Information Specialists, allowing them to focus on callers needing immediate assistance and their healthcare providers. These results will lead to improvement of this valuable HAB outreach, education and surveillance tool. Formal evaluation is recommended for future HAB outreach and educational materials.

  20. The Blooming Anatomy Tool (BAT): A Discipline-Specific Rubric for Utilizing Bloom's Taxonomy in the Design and Evaluation of Assessments in the Anatomical Sciences

    Science.gov (United States)

    Thompson, Andrew R.; O'Loughlin, Valerie D.

    2015-01-01

    Bloom's taxonomy is a resource commonly used to assess the cognitive level associated with course assignments and examination questions. Although widely utilized in educational research, Bloom's taxonomy has received limited attention as an analytical tool in the anatomical sciences. Building on previous research, the Blooming Anatomy Tool (BAT)…

  1. Intracellular nitrate of marine diatoms as a driver of anaerobic nitrogen cycling in sinking aggregates

    DEFF Research Database (Denmark)

    Kamp, Anja; Stief, Peter; Bristow, Laura A.

    2016-01-01

    Diatom-bacteria aggregates are key for the vertical transport of organic carbon in the ocean. Sinking aggregates also represent pelagic microniches with intensified microbial activity, oxygen depletion in the center, and anaerobic nitrogen cycling. Since some of the aggregate-forming diatom species......-bacteria aggregates. Stable 15N isotope incubations under dark and anoxic conditions revealed that axenic S. marinoi is able to reduce intracellular nitrate to ammonium that is immediately excreted by the cells. When exposed to a light:dark cycle and oxic conditions, S. marinoi stored nitrate intracellularly....... Thirty-one percent of the diatom-derived nitrate was converted to nitrogen gas, indicating that a substantial fraction of the intracellular nitrate pool of S. marinoi becomes available to the aggregate-associated bacterial community. Only 5% of the intracellular nitrate was reduced to ammonium, while 59...

  2. Biofouling in capillary and spiral wound membranes facilitated by marine algal bloom

    KAUST Repository

    Villacorte, L.O.

    2017-10-11

    Algal-derived organic matter (AOM), particularly transparent exopolymer particles, has been suspected to facilitate biofilm development in membrane systems (e.g., seawater reverse osmosis). This study demonstrates the possible role of AOM on biofouling in membrane systems affected by marine algal blooms. The tendency of AOM from bloom-forming marine algae to adhere to membranes and its ability to enhance biofilm growth were measured using atomic force microscopy, flow cytometry, liquid chromatography and accelerated membrane biofouling experiments. Adhesion force measurements indicate that AOM tends to adhere to clean membranes and even more strongly to AOM-fouled membranes. Batch growth tests illustrate that the capacity of seawater to support bacterial growth can significantly increase with AOM concentration. Biofouling experiments with spiral wound and capillary membranes illustrate that when nutrients availability are not limited in the feed water, a high concentration of AOM – whether in suspension or attached to the membrane – can substantially accelerates biofouling. A significantly lower biofouling rate was observed on membranes exposed to feed water spiked only with AOM or easily biodegradable nutrients. The abovementioned findings indicate that AOM facilitates the onset of membrane biofouling primarily as a conditioning platform and to some extent as a nutrient source for biofilm-forming bacteria.

  3. Characterization of dominant and cellulolytic bacterial communities along the gut of silver carp Hypophthalmichthys molitrix during cyanobacterial blooms

    Science.gov (United States)

    Luo, Congqiang; Yi, Chunlong; Ni, Leyi; Guo, Longgen

    2017-05-01

    Silver carp is one of the most important planktivorous fish in Chinese aquaculture and plays a significant role controlling cyanobacterial blooms. A balanced gut microbiota is crucial for growth and health of the host because of its important roles in immune defense, digestion of complex carbohydrates, and production of enterocytes. In our study, the dominant bacterial and cellulolytic bacterial ( Clostridium I, Clostridium III, Clostridium XIVab, and Fibrobacter) communities in the contents and mucus of the silver carp gut (foregut, midgut, and hindgut) were analyzed by denaturing gradient gel electrophoresis and quantitative polymerase chain reaction (qPCR) analyses. The results revealed that the dominant and cellulolytic bacterial communities were significantly different among gut regions as well as in contents and mucus. Bacterial diversity and richness in contents and mucus increased along the gut and were higher in contents than those in local mucus. A sequence analysis of gut samples exhibited the conservative phylotypes of Proteobacteria, Actinobacteria, and Firmicutes. The gut of silver carp harbored an abundance of cellulolytic bacteria, particularly Clostridium XIV ab. The foregut segment had the highest proportions of the four cellulolytic bacteria, followed by the midgut and hindgut. However, the proportions of cellulolytic species in the silver carp gut was much lower than those in the terrestrial vertebrate gastrointestinal tract. We conclude that gut bacteria could help silver carp obtain energy from cyanobacteria, which may be why silver carp can maintain high growth rates during cyanobacterial blooms.

  4. Characteristics of Bacterial Communities in Cyanobacteria-Blooming Aquaculture Wastewater Influenced by the Phytoremediation with Water Hyacinth

    Directory of Open Access Journals (Sweden)

    Qing Zhou

    2017-12-01

    Full Text Available Cyanobacterial blooms often occur in aquaculture wastewater in China. A floating plant, water hyacinth has been widely used to treat this wastewater. Little is known, however, about bacterial community characteristics and the risk of potential pathogens in cyanobacteria-blooming aquaculture wastewater remediated by water hyacinth. In wastewater treated with water hyacinth, we used culture enumeration and high-throughput sequencing to explore the characteristics of bacterial communities, the status of coliform bacteria, and pathogenic bacteria potentially conducive to human disease. Our results indicated that the relative abundance of Acidobacteria, Planctomycetes, Actinobacteria, Chlorobi, Cyanobacteria, Proteobacteria, and phylum OD1 in cyanobacteria-blooming aquaculture wastewater were significantly influenced by water hyacinth. After 30 days, the relative abundance of Proteobacteria and phylum OD1 in the water hyacinth treatments increased remarkably, while the relative abundance of the other 5 phyla in treatment was significantly reduced compared with the controls. In 21 major families, the relative abundance of Comamonadaceae, Oxalobacteraceae, Rhodocylclaceae, and an unnamed group from phylum OD1 increased significantly in the water hyacinth treatments compared with the controls. The number of total coliforms in wastewater treated by water hyacinth was significantly elevated and higher than controls during the first 6–18 days, with the maximum reaching 23,800 MPN/L. The level of potential pathogenic bacteria in wastewater treated by water hyacinth significantly reduced compared with the controls after 18 days, but it significantly increased from the initial level. It appears that water hyacinth by itself is not an effective treatment for reducing potential pathogens in aquaculture water.

  5. Legionella pneumophila transcriptome during intracellular multiplication in human macrophages

    Directory of Open Access Journals (Sweden)

    Sebastien P Faucher

    2011-04-01

    Full Text Available Legionella pneumophila is the causative agent of Legionnaires’ disease, an acute pulmonary infection. L. pneumophila is able to infect and multiply in both phagocytic protozoa, such as Acanthamoeba castellanii, and mammalian professional phagocytes. The best-known L. pneumophila virulence determinant is the Icm/Dot Type IVB secretion system (TFBSS, which is used to translocate more than 150 effector proteins to host cells. While the transcriptional response of Legionella to the intracellular environment of A. castellanii has been investigated, much less is known about the Legionella transcriptional response inside human macrophages. In this study, the transcriptome of L. pneumophila was monitored during exponential and post-exponential phase in rich AYE broth as well as during infection of human cultured macrophages. This was accomplished with microarrays and an RNA amplification procedure called SCOTS to detect small amounts of mRNA from low numbers of intracellular bacteria. Among the genes induced intracellularly are those involved in amino acid biosynthetic pathways leading to L-arginine, L-histidine and L-proline as well as many transport systems involved in amino acid and iron uptake. Gene involved in catabolism of glycerol is also induced during intracellular growth and could be used as a carbon source. The genes encoding the Icm/Dot system are not differentially expressed inside cells compared to control bacteria grown in rich broth, but the genes encoding several translocated effectors are strongly induced. Moreover, we used the transcriptome data to predict previously unrecognized Icm/Dot effector genes based on their expression pattern and confirmed translocation for three candidates. This study provides a comprehensive view of how L. pneumophila responds to the human macrophage intracellular environment.

  6. Improving Bloom Filter Performance on Sequence Data Using k-mer Bloom Filters.

    Science.gov (United States)

    Pellow, David; Filippova, Darya; Kingsford, Carl

    2017-06-01

    Using a sequence's k-mer content rather than the full sequence directly has enabled significant performance improvements in several sequencing applications, such as metagenomic species identification, estimation of transcript abundances, and alignment-free comparison of sequencing data. As k-mer sets often reach hundreds of millions of elements, traditional data structures are often impractical for k-mer set storage, and Bloom filters (BFs) and their variants are used instead. BFs reduce the memory footprint required to store millions of k-mers while allowing for fast set containment queries, at the cost of a low false positive rate (FPR). We show that, because k-mers are derived from sequencing reads, the information about k-mer overlap in the original sequence can be used to reduce the FPR up to 30 × with little or no additional memory and with set containment queries that are only 1.3 - 1.6 times slower. Alternatively, we can leverage k-mer overlap information to store k-mer sets in about half the space while maintaining the original FPR. We consider several variants of such k-mer Bloom filters (kBFs), derive theoretical upper bounds for their FPR, and discuss their range of applications and limitations.

  7. Visual Literacy in Bloom: Using Bloom's Taxonomy to Support Visual Learning Skills.

    Science.gov (United States)

    Arneson, Jessie B; Offerdahl, Erika G

    2018-01-01

    Vision and Change identifies science communication as one of the core competencies in undergraduate biology. Visual representations are an integral part of science communication, allowing ideas to be shared among and between scientists and the public. As such, development of scientific visual literacy should be a desired outcome of undergraduate instruction. We developed the Visualization Blooming Tool (VBT), an adaptation of Bloom's taxonomy specifically focused on visual representations, to aid instructors in designing instruction and assessments to target scientific visual literacy in undergraduate instruction. In this article, we identify the need for the VBT, describe its development, and provide concrete examples of its application to a curriculum redesign effort in undergraduate biochemistry. © 2018 J. B. Arneson and E. G. Offerdahl. CBE—Life Sciences Education © 2018 The American Society for Cell Biology. This article is distributed by The American Society for Cell Biology under license from the author(s). It is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

  8. Decrease of NH4+-N by bacterioplankton accelerated the removal of cyanobacterial blooms in aerated aquatic ecosystem.

    Science.gov (United States)

    Yang, Xi; Xie, Ping; Ma, Zhimei; Wang, Qing; Fan, Huihui; Shen, Hong

    2013-11-01

    We used aerated systems to assess the influence of the bacterioplankton community on cyanobacterial blooms in algae/post-bloom of Lake Taihu, China. Bacterioplankton community diversity was evaluated by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) fingerprinting. Chemical analysis and nitrogen dynamic changes illustrated that NH4+-N was nitrified to NO2--N and NO3--N by bacterioplankton. Finally, NH4+-N was exhausted and NO3--N was denitrified to NO2--N, while the accumulation of NO2--N indicated that bacterioplankton with completely aerobic denitrification ability were lacking in the water samples collected from Lake Taihu. We suggested that adding completely aerobic denitrification bacteria (to denitrify NO2--N to N2) would improve the water quality. PCR-DGGE and sequencing results showed that more than1/3 of the bacterial species were associated with the removal of nitrogen, and Acidovorax temperans was the dominant one. PCR-DGGE, variation of nitrogen, removal efficiencies of chlorophyll-a and canonical correspondence analysis indicated that the bacterioplanktonsignificantly influenced the physiological and biochemical changes of cyanobacteria. Additionally, the unweighted pair-group method with arithmetic means revealed there was no obvious harm to the microecosystem from aeration. The present study demonstrated that bacterioplankton can play crucial roles in aerated ecosystems, which could control the impact of cyanobacterial blooms in eutrophicated fresh water systems.

  9. Response of marine bacterioplankton to a massive under-ice phytoplankton bloom in the Chukchi Sea (Western Arctic Ocean)

    Science.gov (United States)

    Ortega-Retuerta, E.; Fichot, C. G.; Arrigo, K. R.; Van Dijken, G. L.; Joux, F.

    2014-07-01

    The activity of heterotrophic bacterioplankton and their response to changes in primary production in the Arctic Ocean is essential to understand biogenic carbon flows in the area. In this study, we explored the patterns of bacterial abundance (BA) and bacterial production (BP) in waters coinciding with a massive under-ice phytoplankton bloom in the Chukchi Sea in summer 2011, where chlorophyll a (chl a) concentrations were up to 38.9 mg m-3. Contrary to our expectations, BA and BP did not show their highest values coinciding with the bloom. In fact, bacterial biomass was only 3.5% of phytoplankton biomass. Similarly, average DOC values were similar inside (average 57.2±3.1 μM) and outside (average 64.3±4.8 μM) the bloom patch. Regression analyses showed relatively weak couplings, in terms of slope values, between chl a or primary production and BA or BP. Multiple regression analyses indicated that both temperature and chl a explained BA and BP variability in the Chukchi Sea. This temperature dependence was confirmed experimentally, as higher incubation temperatures (6.6 °C vs. 2.2 °C) enhanced BA and BP, with Q10 values of BP up to 20.0. Together, these results indicate that low temperatures in conjunction with low dissolved organic matter release can preclude bacteria to efficiently process a higher proportion of carbon fixed by phytoplankton, with further consequences on the carbon cycling in the area.

  10. Progress in Understanding Harmful Algal Blooms: Paradigm Shifts and New Technologies for Research, Monitoring, and Management

    Science.gov (United States)

    Anderson, Donald M.; Cembella, Allan D.; Hallegraeff, Gustaaf M.

    2012-01-01

    The public health, tourism, fisheries, and ecosystem impacts from harmful algal blooms (HABs) have all increased over the past few decades. This has led to heightened scientific and regulatory attention, and the development of many new technologies and approaches for research and management. This, in turn, is leading to significant paradigm shifts with regard to, e.g., our interpretation of the phytoplankton species concept (strain variation), the dogma of their apparent cosmopolitanism, the role of bacteria and zooplankton grazing in HABs, and our approaches to investigating the ecological and genetic basis for the production of toxins and allelochemicals. Increasingly, eutrophication and climate change are viewed and managed as multifactorial environmental stressors that will further challenge managers of coastal resources and those responsible for protecting human health. Here we review HAB science with an eye toward new concepts and approaches, emphasizing, where possible, the unexpected yet promising new directions that research has taken in this diverse field.

  11. Physical and biological data collected along the Texas, Mississippi, and Florida Gulf coasts in the Gulf of Mexico as part of the Harmful Algal BloomS Observing System from 19 Aug 1953 to 11 July 2014 (NODC Accession 0120767)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — HABSOS (Harmful Algal BloomS Observing System) is a data collection and distribution system for harmful algal bloom (HAB) information in the Gulf of Mexico. The goal...

  12. Harmful Freshwater Algal Blooms, With an Emphasis on Cyanobacteria

    Directory of Open Access Journals (Sweden)

    Hans W. Paerl

    2001-01-01

    Full Text Available Suspended algae, or phytoplankton, are the prime source of organic matter supporting food webs in freshwater ecosystems. Phytoplankton productivity is reliant on adequate nutrient supplies; however, increasing rates of nutrient supply, much of it manmade, fuels accelerating primary production or eutrophication. An obvious and problematic symptom of eutrophication is rapid growth and accumulations of phytoplankton, leading to discoloration of affected waters. These events are termed blooms. Blooms are a prime agent of water quality deterioration, including foul odors and tastes, deoxygenation of bottom waters (hypoxia and anoxia, toxicity, fish kills, and food web alterations. Toxins produced by blooms can adversely affect animal (including human health in waters used for recreational and drinking purposes. Numerous freshwater genera within the diverse phyla comprising the phytoplankton are capable of forming blooms; however, the blue-green algae (or cyanobacteria are the most notorious bloom formers. This is especially true for harmful toxic, surface-dwelling, scum-forming genera (e.g., Anabaena, Aphanizomenon, Nodularia, Microcystis and some subsurface bloom-formers (Cylindrospermopsis, Oscillatoria that are adept at exploiting nutrient-enriched conditions. They thrive in highly productive waters by being able to rapidly migrate between radiance-rich surface waters and nutrient-rich bottom waters. Furthermore, many harmful species are tolerant of extreme environmental conditions, including very high light levels, high temperatures, various degrees of desiccation, and periodic nutrient deprivation. Some of the most noxious cyanobacterial bloom genera (e.g., Anabaena, Aphanizomenon, Cylindrospermopsis, Nodularia are capable of fixing atmospheric nitrogen (N2, enabling them to periodically dominate under nitrogen-limited conditions. Cyanobacteria produce a range of organic compounds, including those that are toxic to higher-ranked consumers, from

  13. Climbing Bloom's taxonomy pyramid: Lessons from a graduate histology course.

    Science.gov (United States)

    Zaidi, Nikki B; Hwang, Charles; Scott, Sara; Stallard, Stefanie; Purkiss, Joel; Hortsch, Michael

    2017-09-01

    Bloom's taxonomy was adopted to create a subject-specific scoring tool for histology multiple-choice questions (MCQs). This Bloom's Taxonomy Histology Tool (BTHT) was used to analyze teacher- and student-generated quiz and examination questions from a graduate level histology course. Multiple-choice questions using histological images were generally assigned a higher BTHT level than simple text questions. The type of microscopy technique (light or electron microscopy) used for these image-based questions did not result in any significant differences in their Bloom's taxonomy scores. The BTHT levels for teacher-generated MCQs correlated positively with higher discrimination indices and inversely with the percent of students answering these questions correctly (difficulty index), suggesting that higher-level Bloom's taxonomy questions differentiate well between higher- and lower-performing students. When examining BTHT scores for MCQs that were written by students in a Multiple-Choice Item Development Assignment (MCIDA) there was no significant correlation between these scores and the students' ability to answer teacher-generated MCQs. This suggests that the ability to answer histology MCQs relies on a different skill set than the aptitude to construct higher-level Bloom's taxonomy questions. However, students significantly improved their average BTHT scores from the midterm to the final MCIDA task, which indicates that practice, experience and feedback increased their MCQ writing proficiency. Anat Sci Educ 10: 456-464. © 2017 American Association of Anatomists. © 2017 American Association of Anatomists.

  14. Thioredoxin 80-Activated-Monocytes (TAMs) Inhibit the Replication of Intracellular Pathogens

    DEFF Research Database (Denmark)

    Cortes-Bratti, Ximena; Brasseres, Eugenie; Herrera-Rodriquez, Fabiola

    2011-01-01

    for a role of TAMs in the control of intracellular bacterial infections. As model pathogens we have chosen Listeria monocytogenes and Brucella abortus which replicate in the cytosol and the endoplasmic reticulum respectively. Our data indicate that TAMs efficiently inhibit intracellular growth of both L....... monocytogenes and B. abortus. Further analysis shows that Trx80 activation prevents the escape of GFP-tagged L. monocytogenes into the cytosol, and induces accumulation of the bacteria within the lysosomes. Inhibition of the lysosomal activity by chloroquine treatment resulted in higher replication of bacteria...

  15. A first step toward liposome-mediated intracellular bacteriophage therapy.

    Science.gov (United States)

    Nieth, Anita; Verseux, Cyprien; Barnert, Sabine; Süss, Regine; Römer, Winfried

    2015-01-01

    The emergence of antibiotic-resistant bacteria presents a severe challenge to medicine and public health. While bacteriophage therapy is a promising alternative to traditional antibiotics, the general inability of bacteriophages to penetrate eukaryotic cells limits their use against resistant bacteria, causing intracellular diseases like tuberculosis. Bacterial vectors show some promise in carrying therapeutic bacteriophages into cells, but also bring a number of risks like an overload of bacterial antigens or the acquisition of virulence genes from the pathogen. As a first step in the development of a non-bacterial vector for bacteriophage delivery into pathogen-infected cells, we attempted to encapsulate bacteriophages into liposomes. Here we report effective encapsulation of the model bacteriophage λeyfp and the mycobacteriophage TM4 into giant liposomes. Furthermore, we show that liposome-associated bacteriophages are taken up into eukaryotic cells more efficiently than free bacteriophages. These are important milestones in the development of an intracellular bacteriophage therapy that might be useful in the fight against multi-drug-resistant intracellular pathogens like Mycobacterium tuberculosis.

  16. Effects of varied nitrate and phosphate supply on polysaccharidic and proteinaceous gel particles production during tropical phytoplankton bloom experiments

    Science.gov (United States)

    Engel, A.; Borchard, C.; Loginova, A.; Meyer, J.; Hauss, H.; Kiko, R.

    2015-04-01

    It has been suggested that oxygen minimum zones (OMZ) will expand in the tropical oceans as a result of global change with potential consequences for marine element cycling, such as an increase in anaerobic nitrogen loss, resulting in a lower supply of nitrate relative to phosphate to the euphotic zone. So far, the effects of changes in nutrient ratios on organic matter recycling and export fluxes are not well understood. Here, were investigated how different phosphate (Varied P: 0.15-1.58 μmol L-1) or nitrate (Varied N: 1.9-21.9 μmol L-1) concentrations affect the abundance and size distribution of polysaccharidic transparent exopolymer particles (TEP), which are suggested to enhance particle aggregation and export fluxes, and on proteinaceous coomassie stainable particles (CSP), a supposedly good substrate for heterotrophic bacteria. Two series of mesocosm bloom experiments were conducted with natural plankton communities collected from the Eastern Tropical North Atlantic (ETNA) close to Cape Verde in October 2012. Until bloom peak, a positive correlation between gel particle abundance and Chl a concentration was determined, linking the release of dissolved gel precursors and the subsequent formation of gel particles to autotrophic production. After bloom peak, gel particle abundance remained stable or even increased, implying a continued partitioning of dissolved into particulate organic matter after biomass production itself ceased. During both experiments, differences between TEP and CSP dynamics were observed; TEP were generally more abundant than CSP. Changes in size distribution indicated aggregation of TEP during the bloom, while newly formed CSP decomposed. Abundance of gel particles clearly increased with nitrate concentration during the second experiment, suggesting that changes in [DIN]:[DIP] ratios can affect gel particle formation with potential consequences for carbon and nitrogen cycling as well as food web dynamics in tropical ecosystems.

  17. Genome reconstructions indicate the partitioning of ecological functions inside a phytoplankton bloom in the Amundsen Sea, Antarctica

    Directory of Open Access Journals (Sweden)

    Tom O Delmont

    2015-10-01

    Full Text Available Antarctica polynyas support intense phytoplankton blooms, impacting their environment by a substantial depletion of inorganic carbon and nutrients. These blooms are dominated by the colony-forming haptophyte Phaeocystis antarctica and they are accompanied by a distinct bacterial population. Yet, the ecological role these bacteria may play in P. antarctica blooms awaits elucidation of their functional gene pool and of the geochemical activities they support. Here, we report on a metagenome (῀160 million reads analysis of the microbial community associated with a P. antarctica bloom event in the Amundsen Sea polynya (West Antarctica. Genomes of the most abundant Bacteroidetes and Proteobacteria populations have been reconstructed and a network analysis indicates a strong functional partitioning of these bacterial taxa. Three of them (SAR92, and members of the Oceanospirillaceae and Cryomorphaceae are found in close association with P. antarctica colonies. Distinct features of their carbohydrate, nitrogen, sulfur and iron metabolisms may serve to support mutualistic relationships with P. antarctica. The SAR92 genome indicates a specialization in the degradation of fatty acids and dimethylsulfoniopropionate (compounds released by P. antarctica into dimethyl sulfide, an aerosol precursor. The Oceanospirillaceae genome carries genes that may enhance algal physiology (cobalamin synthesis. Finally, the Cryomorphaceae genome is enriched in genes that function in cell or colony invasion. A novel pico-eukaryote, Micromonas related genome (19.6 Mb, ~94% completion was also recovered. It contains the gene for an anti-freeze protein, which is lacking in Micromonas at lower latitudes. These draft genomes are representative for abundant microbial taxa across the Southern Ocean surface.

  18. Salmonella Intracellular Lifestyles and Their Impact on Host-to-Host Transmission.

    Science.gov (United States)

    Pucciarelli, M Graciela; García-Del Portillo, Francisco

    2017-07-01

    More than a century ago, infections by Salmonella were already associated with foodborne enteric diseases with high morbidity in humans and cattle. Intestinal inflammation and diarrhea are hallmarks of infections caused by nontyphoidal Salmonella serovars, and these pathologies facilitate pathogen transmission to the environment. In those early times, physicians and microbiologists also realized that typhoid and paratyphoid fever caused by some Salmonella serovars could be transmitted by "carriers," individuals outwardly healthy or at most suffering from some minor chronic complaint. In his pioneering study of the nontyphoidal serovar Typhimurium in 1967, Takeuchi published the first images of intracellular bacteria enclosed by membrane-bound vacuoles in the initial stages of the intestinal epithelium penetration. These compartments, called Salmonella -containing vacuoles, are highly dynamic phagosomes with differing biogenesis depending on the host cell type. Single-cell studies involving real-time imaging and gene expression profiling, together with new approaches based on genetic reporters sensitive to growth rate, have uncovered unprecedented heterogeneous responses in intracellular bacteria. Subpopulations of intracellular bacteria displaying fast, reduced, or no growth, as well as cytosolic and intravacuolar bacteria, have been reported in both in vitro and in vivo infection models. Recent investigations, most of them focused on the serovar Typhimurium, point to the selection of persisting bacteria inside macrophages or following an autophagy attack in fibroblasts. Here, we discuss these heterogeneous intracellular lifestyles and speculate on how these disparate behaviors may impact host-to-host transmissibility of Salmonella serovars.

  19. Sulfur bacteria in wastewater stabilization ponds periodically affected by the ‘red-water’ phenomenon

    NARCIS (Netherlands)

    Belila, A.; Abbas, B.; Fazaa, I.; Saidi, N.; Snoussi, M.; Hassen, A.; Muyzer, G.

    2012-01-01

    Several wastewater stabilization ponds (WSP) in Tunisia suffer periodically from the ‘red-water’ phenomenon due to blooming of purple sulfur bacteria, indicating that sulfur cycle is one of the main element cycles in these ponds. In this study, we investigated the microbial diversity of the El

  20. Sulfur bacteria in wastewater stabilization ponds periodically affected by the 'red-water' phenomenon

    NARCIS (Netherlands)

    Belila, A.; Abbas, B.; Fazaa, I.; Saidi, N.; Snoussi, M.; Hassen, A.; Muyzer, G.

    2013-01-01

    Several wastewater stabilization ponds (WSP) in Tunisia suffer periodically from the ‘red-water’ phenomenon due to blooming of purple sulfur bacteria, indicating that sulfur cycle is one of the main element cycles in these ponds. In this study, we investigated the microbial diversity of the El

  1. A novel earth observation based ecological indicator for cyanobacterial blooms

    Science.gov (United States)

    Anttila, Saku; Fleming-Lehtinen, Vivi; Attila, Jenni; Junttila, Sofia; Alasalmi, Hanna; Hällfors, Heidi; Kervinen, Mikko; Koponen, Sampsa

    2018-02-01

    Cyanobacteria form spectacular mass occurrences almost annually in the Baltic Sea. These harmful algal blooms are the most visible consequences of marine eutrophication, driven by a surplus of nutrients from anthropogenic sources and internal processes of the ecosystem. We present a novel Cyanobacterial Bloom Indicator (CyaBI) targeted for the ecosystem assessment of eutrophication in marine areas. The method measures the current cyanobacterial bloom situation (an average condition of recent 5 years) and compares this to the estimated target level for 'good environmental status' (GES). The current status is derived with an index combining indicative bloom event variables. As such we used seasonal information from the duration, volume and severity of algal blooms derived from earth observation (EO) data. The target level for GES was set by using a remote sensing based data set named Fraction with Cyanobacterial Accumulations (FCA; Kahru & Elmgren, 2014) covering years 1979-2014. Here a shift-detection algorithm for time series was applied to detect time-periods in the FCA data where the level of blooms remained low several consecutive years. The average conditions from these time periods were transformed into respective CyaBI target values to represent target level for GES. The indicator is shown to pass the three critical factors set for marine indicator development, namely it measures the current status accurately, the target setting can be scientifically proven and it can be connected to the ecosystem management goal. An advantage of the CyaBI method is that it's not restricted to the data used in the development work, but can be complemented, or fully applied, by using different types of data sources providing information on cyanobacterial accumulations.

  2. Are Low Salinity Waters the Remedy to Noctiluca scintillans Blooms in the Arabian Sea?

    Science.gov (United States)

    Gibson, J.

    2017-12-01

    Noctiluca scintillans (Noctiluca) is a mixotrophic, green dinoflagellate that for the past two decades has been producing problematic algal blooms in the Arabian Sea (AS). As a mixotroph, Noctiluca obtains energy from both consumption of phytoplankton as well as its intracellular photosynthesizing endosymbionts named, Pedinomonas noctilucae. It is this autotrophic and heterotrophic dual capability that has largely enabled Noctiluca to be a highly dominant species at the planktonic trophic layer in the AS. Exacerbated by non-point source/point-source pollution in the AS, ocean acidification, and intensified monsoons, Noctiluca currently algal blooms can be as big as three times the size of Texas. By depleting the AS of oxygen, clogging the gills of fish, and altering the AS food web, these algal blooms result in mass fish die offs. In turn this propagates financial and food insecurity issues in countless coastal communities. However, through satellite imaging over the years, it has been observed that the proliferation of Noctiluca is precluded or encounters a "wall" about mid-way along the west coast of India. It is theorized that this "wall" is due to a significant change in salinity. Snow from atop the Himalayan Mountains melts and adds fresh water to the Bay of Bengal (BB), and in winter the East Indian Coastal Current (EICC) carries this fresher water around the southern tip of India and towards the AS. It is believed that this dilution effect impedes the growth of Noctiluca further south. Ultimately, in this study the salinity gradient from the Bay of Bengal (BB) around the horn of India into the AS was replicated in six pairs of culture bottles. Noctiluca was grown in six different salinities including 26, 28, 30, 32, 34, and 38 psu. Algae grown in the 34 and 38 psu bottles, were healthier and 38 psu treated Noctiluca provided optimal conditions for its photosynthesizing endosymbionts. Noctiluca does not grow well at lower salinities, thus applications of low

  3. Indian satellite IRS-P4 (OCEANSAT). Monitoring algal blooms in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Matondkar, S.G.P.; Bhat, S.R.; Dwivedi, R.M.; Nayak, S.R.

    Sea open waters. The time series from ocean colour monitor (OCM) onboard OCEANSAT indicates this bloom gradually extending as far as Oman. Bloom that generally initiates in the last week of January was found to persist until mid-March....

  4. Siderocalin inhibits the intracellular replication of Mycobacterium tuberculosis in macrophages

    DEFF Research Database (Denmark)

    Johnson, Erin E; Srikanth, Chittur V; Sandgren, Andreas

    2010-01-01

    that siderocalin expression is upregulated following M.tb infection of mouse macrophage cell lines and primary murine alveolar macrophages. Furthermore, siderocalin added exogenously as a recombinant protein or overexpressed in the RAW264.7 macrophage cell line inhibited the intracellular growth of the pathogen......Siderocalin is a secreted protein that binds to siderophores to prevent bacterial iron acquisition. While it has been shown to inhibit the growth of Mycobacterium tuberculosis (M.tb) in extracellular cultures, its effect on this pathogen within macrophages is not clear. Here, we show....... A variant form of siderocalin, which is expressed only in the macrophage cytosol, inhibited intracellular M.tb growth as effectively as the normal, secreted form, an observation that provides mechanistic insight into how siderocalin might influence iron acquisition by the bacteria in the phagosome. Our...

  5. Stochastic models of intracellular transport

    KAUST Repository

    Bressloff, Paul C.

    2013-01-09

    The interior of a living cell is a crowded, heterogenuous, fluctuating environment. Hence, a major challenge in modeling intracellular transport is to analyze stochastic processes within complex environments. Broadly speaking, there are two basic mechanisms for intracellular transport: passive diffusion and motor-driven active transport. Diffusive transport can be formulated in terms of the motion of an overdamped Brownian particle. On the other hand, active transport requires chemical energy, usually in the form of adenosine triphosphate hydrolysis, and can be direction specific, allowing biomolecules to be transported long distances; this is particularly important in neurons due to their complex geometry. In this review a wide range of analytical methods and models of intracellular transport is presented. In the case of diffusive transport, narrow escape problems, diffusion to a small target, confined and single-file diffusion, homogenization theory, and fractional diffusion are considered. In the case of active transport, Brownian ratchets, random walk models, exclusion processes, random intermittent search processes, quasi-steady-state reduction methods, and mean-field approximations are considered. Applications include receptor trafficking, axonal transport, membrane diffusion, nuclear transport, protein-DNA interactions, virus trafficking, and the self-organization of subcellular structures. © 2013 American Physical Society.

  6. Multi-species bacterial biofilm and intracellular infection in otitis media

    Directory of Open Access Journals (Sweden)

    Thornton Ruth B

    2011-10-01

    Full Text Available Abstract Background Bacteria which are metabolically active yet unable to be cultured and eradicated by antibiotic treatment are present in the middle ear effusion of children with chronic otitis media with effusion (COME and recurrent acute otitis media (rAOM. These observations are suggestive of biofilm presence or intracellular sequestration of bacteria and may play a role in OM pathogenesis. The aim of this project is to provide evidence for the presence of otopathogenic bacteria intracellularly or within biofilm in the middle ear mucosa of children with COME or rAOM. Methods Middle ear mucosal biopsies from 20 children with COME or rAOM were examined for otopathogenic bacteria (either in biofilm or located intracellularly using transmission electron microscopy (TEM or species specific fluorescent in situ hybridisation (FISH and confocal laser scanning microscopy (CLSM. One healthy control biopsy from a child undergoing cochlear implant surgery was also examined. Results No bacteria were observed in the healthy control sample. In 2 of the 3 biopsies imaged using TEM, bacteria were observed in mucus containing vacuoles within epithelial cells. Bacterial species within these could not be identified and biofilm was not observed. Using FISH with CLSM, bacteria were seen in 15 of the 17 otitis media mucosal specimens. In this group, 11 (65% of the 17 middle ear mucosal biopsies showed evidence of bacterial biofilm and 12 demonstrated intracellular bacteria. 52% of biopsies were positive for both biofilm and intracellular bacteria. At least one otopathogen was identified in 13 of the 15 samples where bacteria were present. No differences were observed between biopsies from children with COME and those with rAOM. Conclusion Using FISH and CLSM, bacterial biofilm and intracellular infection with known otopathogens are demonstrated on/in the middle ear mucosa of children with COME and/or rAOM. While their role in disease pathogenesis remains to be

  7. Bloom's Taxonomy: Improving Assessment and Teaching-Learning Process

    Science.gov (United States)

    Chandio, Muhammad Tufail; Pandhiani, Saima Murtaza; Iqbal, Rabia

    2016-01-01

    This research study critically analyzes the scope and contribution of Bloom's Taxonomy in both assessment and teaching-learning process. Bloom's Taxonomy consists of six stages, namely; remembering, understanding, applying, analyzing, evaluating and creating and moves from lower degree to the higher degree. The study applies Bloom's Taxonomy to…

  8. A Preliminary Bloom's Taxonomy Assessment of End-of-Chapter Problems in Business School Textbooks

    Science.gov (United States)

    Marshall, Jennings B.; Carson, Charles M.

    2008-01-01

    This article examines textbook problems used in a sampling of some of the most common core courses found in schools of business to ascertain what level of learning, as defined by Bloom's Taxonomy, is required to provide a correct answer. A set of working definitions based on Bloom's Taxonomy (Bloom & Krathwohl, 1956) was developed for the six…

  9. A new method of describing phytoplankton blooms: Examples from Helgoland Roads

    Science.gov (United States)

    Mieruch, S.; Freund, J. A.; Feudel, U.; Boersma, M.; Janisch, S.; Wiltshire, K. H.

    2010-01-01

    Phytoplankton blooms, in their pivotal position in pelagic seasonal succession require precise classification criteria in order to evaluate such parameters as bloom start, bloom timing, bloom maximum and growth rates. Such bloom parameters are linked directly to species and bloom specific features. Currently the phytoplankton bloom concept, though intuitively clear, lacks operational criteria allowing the precise definition of bloom parameters. We present a semi-quantitative method of classification of marine phytoplankton blooms based on an algorithmic estimation of several bloom descriptors computed from densely recorded phytoplankton data, like the Helgoland Roads long-term time series. Combining these descriptors we propose a novel classification scheme which may serve useful in the discussion of species fitness, competition and succession of marine algae. Special emphasis is put on the detection of the bloom start, because of its crucial importance for many current research topics, including trigger mechanisms and climate-induced temporal shifts in the context of the match/mismatch hypothesis. Visual examination of scatter plots of these parameters leads us to propose three types of blooming algae.

  10. A Ceratium hirundinella (O.F. Müller) bloom in Hartbeespoort Dam ...

    African Journals Online (AJOL)

    During the late winter to early spring of 1999 Ceratium hirundinella was recorded for the first time in the Hartbeespoort Dam, South Africa, and in bloom forming conditions. The C. hirundinella bloom started in July 1999 after complete mixing occurred and a Microcystis aeruginosa bloom disappeared. C. hirundinella ...

  11. Getting “Inside” Type I IFNs: Type I IFNs in Intracellular Bacterial Infections

    Directory of Open Access Journals (Sweden)

    Deann T. Snyder

    2017-01-01

    Full Text Available Type I interferons represent a unique and complex group of cytokines, serving many purposes during innate and adaptive immunity. Discovered in the context of viral infections, type I IFNs are now known to have myriad effects in infectious and autoimmune disease settings. Type I IFN signaling during bacterial infections is dependent on many factors including whether the infecting bacterium is intracellular or extracellular, as different signaling pathways are activated. As such, the repercussions of type I IFN induction can positively or negatively impact the disease outcome. This review focuses on type I IFN induction and downstream consequences during infection with the following intracellular bacteria: Chlamydia trachomatis, Listeria monocytogenes, Mycobacterium tuberculosis, Salmonella enterica serovar Typhimurium, Francisella tularensis, Brucella abortus, Legionella pneumophila, and Coxiella burnetii. Intracellular bacterial infections are unique because the bacteria must avoid, circumvent, and even co-opt microbial “sensing” mechanisms in order to reside and replicate within a host cell. Furthermore, life inside a host cell makes intracellular bacteria more difficult to target with antibiotics. Because type I IFNs are important immune effectors, modulating this pathway may improve disease outcomes. But first, it is critical to understand the context-dependent effects of the type I IFN pathway in intracellular bacterial infections.

  12. Declines in predatory fish promote bloom-forming macroalgae

    NARCIS (Netherlands)

    Eriksson, Britas Klemens; Ljunggren, Lars; Sandstrom, Alfred; Johansson, Gustav; Mattila, Johanna; Rubach, Anja; Raberg, Sonja; Snickars, Martin; Sandström, Alfred; Råberg, Sonja; Stokesbury, K.

    2009-01-01

    In the Baltic Sea, increased dominance of ephemeral and bloom-forming algae is presently attributed to increased nutrient loads. Simultaneously, coastal predatory fish are in strong decline. Using field data from nine areas covering a 700-km coastline, we examined whether formation of macroalgal

  13. Alan Bloom's "The Closing of the American Mind": Two Perspectives.

    Science.gov (United States)

    Greene, Maxine; Birenbaum, William

    This colloquium report contains two papers that present perspectives on the book, "The Closing of the American Mind," by Allan Bloom. The first paper, by Maxine Greene, covers the book's philosophy. It asserts that the book deals with issues of American literacy on a superficial level, and actually is more concerned with refuting points…

  14. Was Bloom's Taxonomy Pointed in the Wrong Direction?

    Science.gov (United States)

    Wineburg, Sam; Schneider, Jack

    2010-01-01

    Bloom's Taxonomy usually is depicted as a pyramid with knowledge at the lowest level and evaluation at the top. For the history classroom, however, that arrangement might be upside down. In history, evaluation is often necessary before new knowledge can be learned. (Contains 1 figure.)

  15. Developing Learning Objectives for Accounting Ethics Using Bloom's Taxonomy

    Science.gov (United States)

    Kidwell, Linda A.; Fisher, Dann G.; Braun, Robert L.; Swanson, Diane L.

    2013-01-01

    The purpose of our article is to offer a set of core knowledge learning objectives for accounting ethics education. Using Bloom's taxonomy of educational objectives, we develop learning objectives in six content areas: codes of ethical conduct, corporate governance, the accounting profession, moral development, classical ethics theories, and…

  16. Conception of Learning Outcomes in the Bloom's Taxonomy Affective Domain

    Science.gov (United States)

    Savickiene, Izabela

    2010-01-01

    The article raises a problematic issue regarding an insufficient base of the conception of learning outcomes in the Bloom's taxonomy affective domain. The search for solutions introduces the conception of teaching and learning in the affective domain as well as presents validity criteria of learning outcomes in the affective domain. The…

  17. Using Bloom's Taxonomy to Teach Students about Plagiarism

    Science.gov (United States)

    Vosen, Melissa A.

    2008-01-01

    Melissa A. Vosen outlines a unit she has designed to help students comprehend the often unclear boundaries and issues surrounding plagiarism. Using Bloom's taxonomy of the cognitive domain, students complete increasingly complex tasks, learning to construct a works cited page and assess scholarly opinions. They also research the consequences of…

  18. Hypoxia sustains cyanobacteria blooms in the Baltic Sea

    NARCIS (Netherlands)

    Funkey, C.P.; Conley, D.J.; Reuss, N.S.; Humborg, C.; Jilbert, T.; Slomp, C.P.

    2014-01-01

    Nutrient over-enrichment is one of the classic triggering mechanisms for the occurrence of cyanobacteria blooms in aquatic ecosystems. In the Baltic Sea, cyanobacteria regularly occur in the late summer months and form nuisance accumulations in surface waters and their abundance has intensified

  19. Fungal parasitism: life cycle, dynamics and impact on cyanobacterial blooms.

    Directory of Open Access Journals (Sweden)

    Mélanie Gerphagnon

    Full Text Available Many species of phytoplankton are susceptible to parasitism by fungi from the phylum Chytridiomycota (i.e. chytrids. However, few studies have reported the effects of fungal parasites on filamentous cyanobacterial blooms. To investigate the missing components of bloom ecosystems, we examined an entire field bloom of the cyanobacterium Anabaena macrospora for evidence of chytrid infection in a productive freshwater lake, using a high resolution sampling strategy. A. macrospora was infected by two species of the genus Rhizosiphon which have similar life cycles but differed in their infective regimes depending on the cellular niches offered by their host. R. crassum infected both vegetative cells and akinetes while R. akinetum infected only akinetes. A tentative reconstruction of the developmental stages suggested that the life cycle of R. crassum was completed in about 3 days. The infection affected 6% of total cells (and 4% of akinètes, spread over a maximum of 17% of the filaments of cyanobacteria, in which 60% of the cells could be parasitized. Furthermore, chytrids may reduce the length of filaments of Anabaena macrospora significantly by "mechanistic fragmentation" following infection. All these results suggest that chytrid parasitism is one of the driving factors involved in the decline of a cyanobacteria blooms, by direct mortality of parasitized cells and indirectly by the mechanistic fragmentation, which could weaken the resistance of A. macrospora to grazing.

  20. A multiprotein nuclear complex connects Fanconi anemia and Bloom syndrome.

    NARCIS (Netherlands)

    Meetei, AR; Sechi, S; Wallisch, M; Yang, D; Young, MK; Joenje, H.; Hoatlin, M.E.

    2003-01-01

    Bloom syndrome (BS) is a genetic disorder associated with dwarfism, immunodeficiency, reduced fertility, and an elevated risk of cancer. To investigate the mechanism of this disease, we isolated from human HeLa extracts three complexes containing the helicase defective in BS, BLM. Interestingly, one

  1. Mitigating cyanobacterial blooms: how effective are 'effective microorganisms'?

    NARCIS (Netherlands)

    Lürling, M.F.L.L.W.; Tolman, Y.; Euwe, M.

    2009-01-01

    This study examined the effects of 'Effective Microorganisms (EM)' on the growth of cyanobacteria, and their ability to terminate cyanobacterial blooms. The EM was tested in the form of 'mudballs' or 'Bokashi-balls', and as a suspension (EM-A) in laboratory experiments. No growth inhibition was

  2. Bloom, Hirsch, and Barthes in the Classroom: Negotiating Cultural Literacy.

    Science.gov (United States)

    Law, Joe K.

    1988-01-01

    Argues that the literature classroom is a forum for negotiating and renegotiating the culture and is not merely a means of transmitting knowledge and values to students. Argues that the consumerist attitude of Bloom and Hirsch towards education must be replaced by an adaptation of Barthes' strategy of rereading literature. (RS)

  3. First record of bloom-forming cyanobacteria, Microcystis aeruginosa ...

    African Journals Online (AJOL)

    This investigation revealed the incidence of floating scum mint green colouration of bloom-forming bluegreen algae, Microcystis aeruginosa Kütz. and M. wesenbergii Komárek in November 2015 at Oyan dam. Water bodies were observed to have mint green appearance. During this observation, all gates and valves were ...

  4. Context discovery using attenuated Bloom codes: model description and validation

    NARCIS (Netherlands)

    Liu, F.; Heijenk, Geert

    A novel approach to performing context discovery in ad-hoc networks based on the use of attenuated Bloom filters is proposed in this report. In order to investigate the performance of this approach, a model has been developed. This document describes the model and its validation. The model has been

  5. Eutrophic urban ponds suffer from cyanobacterial blooms: Dutch examples

    NARCIS (Netherlands)

    Waajen, Guido W. A. M.; Faassen, Elisabeth J.; Lurling, Miquel

    2014-01-01

    Ponds play an important role in urban areas. However, cyanobacterial blooms counteract the societal need for a good water quality and pose serious health risks for citizens and pets. To provide insight into the extent and possible causes of cyanobacterial problems in urban ponds, we conducted a

  6. Occurrence and Deleterious Effects of Algal Blooms Associated With ...

    African Journals Online (AJOL)

    Bloom-forming algal families found in association included members of the phytoplankton class Chlorophyceae: (Pediastrium spp and Spirogyra spp.), the Bacillariophyceae which included Synedra, Melosira and Nitzschia species and potentially toxin-producing genera of the class Cyanophyceae (Microcystis, Anabaena, ...

  7. Hydrodynamic control of microphytoplankton bloom in a coastal sea

    Indian Academy of Sciences (India)

    ... and weak winds left undisturbed, the transient bloom. The phytoplankton aggregates have implication as food resource in the benthic region implying higher fishery potential, in carbon dioxide sequestration (carbon burial) and in efforts towards improving remote sensing algorithms for chlorophyll in the coastal region.

  8. The New Bloom's Taxonomy: Implications for Music Education

    Science.gov (United States)

    Hanna, Wendell

    2007-01-01

    Academic programs use objective and standardized assessment criteria. Music education programs have avoided such objective assessments via the assertion of subjectivity and aesthetics in music learning. In this article, the author introduces the revised Bloom's taxonomy as a tool to translate music education outcomes into objective educational…

  9. Physical processes contributing to harmful algal blooms in Saldanha ...

    African Journals Online (AJOL)

    of black mussel Mytilus galloprovincialis in South Africa. Mussel farming started there in 1985 and the present level of production is some 2 700 tons per annum. Since 1994, disruption of harvesting as a result of the presence of harmful algal species has been a regular late-summer phenomenon. Toxic blooms that are ...

  10. Biological control of Microcystis dominated harmful algal blooms ...

    African Journals Online (AJOL)

    Freshwater resources are now threatened by the presence and increase of harmful algal blooms (HAB) all over the world. The HABs are sometimes a direct result of anthropogenic pollution entering water bodies, such as partially treated nutrient-rich effluents and the leaching of fertilisers and animal wastes. The impact of ...

  11. Tropical cyanobacterial blooms: a review of prevalence, problem taxa, toxins and influencing environmental factors

    Directory of Open Access Journals (Sweden)

    Maxine A.D. Mowe

    2014-12-01

    Full Text Available Toxic cyanobacterial blooms are a major issue in freshwater systems in many countries. The potentially toxic species and their ecological causes are likely to be different in tropical zones from those in temperate water bodies; however, studies on tropical toxic cyanobacterial blooms are sporadic and currently there is no global synthesis. In this review, we examined published information on tropical cyanobacterial bloom occurrence and toxin production to investigate patterns in their growth and distribution. Microcystis was the most frequently occurring bloom genus throughout tropical Asia, Africa and Central America, while Cylindrospermopsis and Anabaena blooms occurred in various locations in tropical Australia, America and Africa. Microcystis blooms were more prevalent during the wet season while Cylindrospermopsis blooms were more prevalent during the dry period. Microcystin was the most encountered toxin throughout the tropics. A meta-analysis of tropical cyanobacterial blooms showed that Microcystis blooms were more associated with higher total nitrogen concentrations, while Cylindrospermopsis blooms were more associated with higher maximum temperatures. Meta-analysis also showed a positive linear relationship between levels of microcystin and N:P (nitrate:phosphate ratio. Tropical African Microcystis blooms were found to have the lowest microcystin levels in relation to biomass and N:P (nitrate:phosphate compared to tropical Asian, Australian and American blooms. There was also no significant correlation between microcystin concentration and cell concentration for tropical African blooms as opposed to tropical Asian and American blooms. Our review illustrates that some cyanobacteria and toxins are more prevalent in tropical areas. While some tropical countries have considerable information regarding toxic blooms, others have few or no reported studies. 

  12. Intracellular ion channels and cancer

    Directory of Open Access Journals (Sweden)

    Luigi eLeanza

    2013-09-01

    Full Text Available Several types of channels play a role in the maintenance of ion homeostasis in subcellular organelles including endoplasmatic reticulum, nucleus, lysosome, endosome and mitochondria. Here we give a brief overview of the contribution of various mitochondrial and other organellar channels to cancer cell proliferation or death. Much attention is focused on channels involved in intracellular calcium signaling and on ion fluxes in the ATP-producing organelle mitochondria. Mitochondrial K+ channels (Ca2+-dependent BKCa and IKCa, ATP-dependent KATP, Kv1.3, two-pore TWIK-related Acid-Sensitive K+ channel-3 (TASK-3, Ca2+ uniporter MCU, Mg2+-permeable Mrs2, anion channels (voltage-dependent chloride channel VDAC, intracellular chloride channel CLIC and the Permeability Transition Pore (MPTP contribute importantly to the regulation of function in this organelle. Since mitochondria play a central role in apoptosis, modulation of their ion channels by pharmacological means may lead to death of cancer cells. The nuclear potassium channel Kv10.1 and the nuclear chloride channel CLIC4 as well as the endoplasmatic reticulum (ER-located inositol 1,4,5-trisphosphate (IP3 receptor, the ER-located Ca2+ depletion sensor STIM1 (stromal interaction molecule 1, a component of the store-operated Ca2+ channel and the ER-resident TRPM8 are also mentioned. Furthermore, pharmacological tools affecting organellar channels and modulating cancer cell survival are discussed. The channels described in this review are summarized on Figure 1. Overall, the view is emerging that intracellular ion channels may represent a promising target for cancer treatment.

  13. Engineering a predatory bacterium as a proficient killer agent for intracellular bio-products recovery

    DEFF Research Database (Denmark)

    Martinez, Virginia; Herencias, Cristina; Jurkevitch, Edouard

    2016-01-01

    This work examines the potential of the predatory bacterium Bdellovibrio bacteriovorus HD100, an obligate predator of other Gram-negative bacteria, as an external cell-lytic agent for recovering valuable intracellular bio-products produced by prey cultures. The bio-product targets to be recovered...

  14. Evidence for an intracellular niche for Bordetella pertussis in broncho-alveolar lavage cells of mice

    NARCIS (Netherlands)

    Hellwig, SMM; Hazenbos, WLW; van de Winkel, JGJ; Mooi, FR

    1999-01-01

    Bordetella pertussis can attach, invade and survive intracellularly in human macrophages in vitro. To study the significance of this bacterial feature in vivo, we analyzed the presence of viable bacteria in broncho-alveolar lavage (BAL) cells of mice infected with B, pertussis. We found B. pertussis

  15. Under Sea Ice phytoplankton bloom detection and contamination in Antarctica

    Science.gov (United States)

    Zeng, C.; Zeng, T.; Xu, H.

    2017-12-01

    Previous researches reported compelling sea ice phytoplankton bloom in Arctic, while seldom reports studied about Antarctic. Here, lab experiment showed sea ice increased the visible light albedo of the water leaving radiance. Even a new formed sea ice of 10cm thickness increased water leaving radiance up to 4 times of its original bare water. Given that phytoplankton preferred growing and accumulating under the sea ice with thickness of 10cm-1m, our results showed that the changing rate of OC4 estimated [Chl-a] varied from 0.01-0.5mg/m3 to 0.2-0.3mg/m3, if the water covered by 10cm sea ice. Going further, varying thickness of sea ice modulated the changing rate of estimating [Chl-a] non-linearly, thus current routine OC4 model cannot estimate under sea ice [Chl-a] appropriately. Besides, marginal sea ice zone has a large amount of mixture regions containing sea ice, water and snow, where is favorable for phytoplankton. We applied 6S model to estimate the sea ice/snow contamination on sub-pixel water leaving radiance of 4.25km spatial resolution ocean color products. Results showed that sea ice/snow scale effectiveness overestimated [Chl-a] concentration based on routine band ratio OC4 model, which contamination increased with the rising fraction of sea ice/snow within one pixel. Finally, we analyzed the under sea ice bloom in Antarctica based on the [Chl-a] concentration trends during 21 days after sea ice retreating. Regardless of those overestimation caused by sea ice/snow sub scale contamination, we still did not see significant under sea ice blooms in Antarctica in 2012-2017 compared with Arctic. This research found that Southern Ocean is not favorable for under sea ice blooms and the phytoplankton bloom preferred to occur in at least 3 weeks after sea ice retreating.

  16. Economic Game Theory to Model the Attenuation of Virulence of an Obligate Intracellular Bacterium.

    Science.gov (United States)

    Tago, Damian; Meyer, Damien F

    2016-01-01

    Diseases induced by obligate intracellular pathogens have a large burden on global human and animal health. Understanding the factors involved in the virulence and fitness of these pathogens contributes to the development of control strategies against these diseases. Based on biological observations, a theoretical model using game theory is proposed to explain how obligate intracellular bacteria interact with their host. The equilibrium in such a game shows that the virulence and fitness of the bacterium is host-triggered and by changing the host's defense system to which the bacterium is confronted, an evolutionary process leads to an attenuated strain. Although, the attenuation procedure has already been conducted in practice in order to develop an attenuated vaccine (e.g., with Ehrlichia ruminantium), there was a lack of understanding of the theoretical basis behind this process. Our work provides a model to better comprehend the existence of different phenotypes and some underlying evolutionary mechanisms for the virulence of obligate intracellular bacteria.

  17. An Artificial Neural Network Based Short-term Dynamic Prediction of Algae Bloom

    Directory of Open Access Journals (Sweden)

    Yao Junyang

    2014-06-01

    Full Text Available This paper proposes a method of short-term prediction of algae bloom based on artificial neural network. Firstly, principal component analysis is applied to water environmental factors in algae bloom raceway ponds to get main factors that influence the formation of algae blooms. Then, a model of short-term dynamic prediction based on neural network is built with the current chlorophyll_a values as input and the chlorophyll_a values in the next moment as output to realize short-term dynamic prediction of algae bloom. Simulation results show that the model can realize short-term prediction of algae bloom effectively.

  18. An overview of the interagency, International Symposium on Cyanobacterial Harmful Algal Blooms (ISOC-HAB): advancing the scientific understanding of freshwater harmful algal blooms.

    Science.gov (United States)

    Hudnell, H Kenneth; Dortch, Quay; Zenick, Harold

    2008-01-01

    There is growing evidence that the spatial and temporal incidence of harmful algal blooms is increasing, posing potential risks to human health and ecosystem sustainability. Currently there are no US Federal guidelines, Water Quality Criteria and Standards, or regulations concerning the management of harmful algal blooms. Algal blooms in freshwater are predominantly cyanobacteria, some of which produce highly potent cyanotoxins. The US Congress mandated a Scientific Assessment of Freshwater Harmful Algal Blooms in the 2004 reauthorization of the Harmful Algal Blooms and Hypoxia Research and Control Act. To further the scientific understanding of freshwater harmful algal blooms, the US Environmental Protection Agency (EPA) established an interagency committee to organize the Interagency, International Symposium on Cyanobacterial Harmful Algal Blooms (ISOC-HAB). A theoretical framework to define scientific issues and a systems approach to implement the assessment and management of cyanobacterial harmful algal blooms were developed as organizing themes for the symposium. Seven major topic areas and 23 subtopics were addressed in Workgroups and platform sessions during the symposium. The primary charge given to platform presenters was to describe the state of the science in the subtopic areas, whereas the Workgroups were charged with identifying research that could be accomplished in the short- and long-term to reduce scientific uncertainties. The proceedings of the symposium, published in this monograph, are intended to inform policy determinations and the mandated Scientific Assessment by describing the scientific knowledge and areas of uncertainty concerning freshwater harmful algal blooms.

  19. Characterization of Karenia brevis blooms on the West Florida Shelf using ocean color satellite imagery: implications for bloom maintenance and evolution

    Science.gov (United States)

    Soto, Inia M.; Muller-Karger, Frank E.; Hu, Chuanmin; Wolny, Jennifer

    2017-01-01

    Satellite ocean color remote sensing techniques, coupled with in situ data, were used to examine the spatial extent and evolution of four Karenia brevis blooms on the West Florida Shelf (WFS) in 2004, 2005, 2006, and 2011. Observations were obtained with the moderate resolution imaging spectroradiometer (MODIS-Aqua). These four blooms were delineated by combining remote-sensing reflectance at 555 nm and normalized fluorescence line height. In 2004 and 2005, the WFS was affected by several hurricanes, including the category 5 storm Hurricane Katrina. These hurricanes led to increased river discharge and vertical mixing which favored bloom intensification and dispersion. No hurricanes passed over the WSF in 2006; however, storms in south Florida may have aided bloom intensification via increased river discharge. In 2011, a bloom appeared off Venice, Florida, where several small creeks discharge. The bloom moved south toward Charlotte Harbor where it intensified and lingered for several months as it received nutrients from riverine discharge and upwelling events. While it is difficult to identify initiation stages of a K. brevis bloom (satellite imagery, the techniques used here provide information about bloom evolution (size, duration, and advection) and insight into factors affecting bloom dynamics.

  20. Spatial Variability of Cyanobacteria and Heterotrophic Bacteria in Lake Taihu (China).

    Science.gov (United States)

    Qian, Haifeng; Lu, Tao; Song, Hao; Lavoie, Michel; Xu, Jiahui; Fan, Xiaoji; Pan, Xiangliang

    2017-09-01

    Cyanobacterial blooms frequently occur in Lake Taihu (China), but the intertwined relationships between biotic and abiotic factors modulating the frequency and duration of the blooms remain enigmatic. To better understand the relationships between the key abiotic and biotic factors and cyanobacterial blooms, we measured the abundance and diversity of prokaryotic organisms by high-throughput sequencing, the abundance of key genes involved in microcystin production and nitrogen fixation or loss as well as several physicochemical parameters at several stations in Lake Taihu during a cyanobacterial bloom of Microcystis sp.. Measurements of the copy number of denitrification-related genes and 16S rRNA analyses show that denitrification potential and denitrifying bacteria abundance increased in concert with non-diazotrophic cyanobacteria (Microcystis sp.), suggesting limited competition between cyanobacteria and heterotrophic denitrifiers for nutrients, although potential bacteria-mediated N loss may hamper Microcystis growth. The present study provides insight into the importance of different abiotic and biotic factors in controlling cyanobacteria and heterotrophic bacteria spatial variability in Lake Taihu.

  1. Harmful algal bloom smart device application: using image analysis and machine learning techniques for classification of harmful algal blooms

    Science.gov (United States)

    Northern Kentucky University and the U.S. EPA Office of Research Development in Cincinnati Agency are collaborating to develop a harmful algal bloom detection algorithm that estimates the presence of cyanobacteria in freshwater systems by image analysis. Green and blue-green alg...

  2. Deep-sea bioluminescence blooms after dense water formation at the ocean surface.

    Science.gov (United States)

    Tamburini, Christian; Canals, Miquel; Durrieu de Madron, Xavier; Houpert, Loïc; Lefèvre, Dominique; Martini, Séverine; D'Ortenzio, Fabrizio; Robert, Anne; Testor, Pierre; Aguilar, Juan Antonio; Samarai, Imen Al; Albert, Arnaud; André, Michel; Anghinolfi, Marco; Anton, Gisela; Anvar, Shebli; Ardid, Miguel; Jesus, Ana Carolina Assis; Astraatmadja, Tri L; Aubert, Jean-Jacques; Baret, Bruny; Basa, Stéphane; Bertin, Vincent; Biagi, Simone; Bigi, Armando; Bigongiari, Ciro; Bogazzi, Claudio; Bou-Cabo, Manuel; Bouhou, Boutayeb; Bouwhuis, Mieke C; Brunner, Jurgen; Busto, José; Camarena, Francisco; Capone, Antonio; Cârloganu, Christina; Carminati, Giada; Carr, John; Cecchini, Stefano; Charif, Ziad; Charvis, Philippe; Chiarusi, Tommaso; Circella, Marco; Coniglione, Rosa; Costantini, Heide; Coyle, Paschal; Curtil, Christian; Decowski, Patrick; Dekeyser, Ivan; Deschamps, Anne; Donzaud, Corinne; Dornic, Damien; Dorosti, Hasankiadeh Q; Drouhin, Doriane; Eberl, Thomas; Emanuele, Umberto; Ernenwein, Jean-Pierre; Escoffier, Stéphanie; Fermani, Paolo; Ferri, Marcelino; Flaminio, Vincenzo; Folger, Florian; Fritsch, Ulf; Fuda, Jean-Luc; Galatà, Salvatore; Gay, Pascal; Giacomelli, Giorgio; Giordano, Valentina; Gómez-González, Juan-Pablo; Graf, Kay; Guillard, Goulven; Halladjian, Garadeb; Hallewell, Gregory; van Haren, Hans; Hartman, Joris; Heijboer, Aart J; Hello, Yann; Hernández-Rey, Juan Jose; Herold, Bjoern; Hößl, Jurgen; Hsu, Ching-Cheng; de Jong, Marteen; Kadler, Matthias; Kalekin, Oleg; Kappes, Alexander; Katz, Uli; Kavatsyuk, Oksana; Kooijman, Paul; Kopper, Claudio; Kouchner, Antoine; Kreykenbohm, Ingo; Kulikovskiy, Vladimir; Lahmann, Robert; Lamare, Patrick; Larosa, Giuseppina; Lattuada, Dario; Lim, Gordon; Presti, Domenico Lo; Loehner, Herbert; Loucatos, Sotiris; Mangano, Salvatore; Marcelin, Michel; Margiotta, Annarita; Martinez-Mora, Juan Antonio; Meli, Athina; Montaruli, Teresa; Moscoso, Luciano; Motz, Holger; Neff, Max; Nezri, Emma Nuel; Palioselitis, Dimitris; Păvălaş, Gabriela E; Payet, Kevin; Payre, Patrice; Petrovic, Jelena; Piattelli, Paolo; Picot-Clemente, Nicolas; Popa, Vlad; Pradier, Thierry; Presani, Eleonora; Racca, Chantal; Reed, Corey; Riccobene, Giorgio; Richardt, Carsten; Richter, Roland; Rivière, Colas; Roensch, Kathrin; Rostovtsev, Andrei; Ruiz-Rivas, Joaquin; Rujoiu, Marius; Russo, Valerio G; Salesa, Francisco; Sánchez-Losa, Augustin; Sapienza, Piera; Schöck, Friederike; Schuller, Jean-Pierre; Schussler, Fabian; Shanidze, Rezo; Simeone, Francesco; Spies, Andreas; Spurio, Maurizio; Steijger, Jos J M; Stolarczyk, Thierry; Taiuti, Mauro G F; Toscano, Simona; Vallage, Bertrand; Van Elewyck, Véronique; Vannoni, Giulia; Vecchi, Manuela; Vernin, Pascal; Wijnker, Guus; Wilms, Jorn; de Wolf, Els; Yepes, Harold; Zaborov, Dmitry; De Dios Zornoza, Juan; Zúñiga, Juan

    2013-01-01

    The deep ocean is the largest and least known ecosystem on Earth. It hosts numerous pelagic organisms, most of which are able to emit light. Here we present a unique data set consisting of a 2.5-year long record of light emission by deep-sea pelagic organisms, measured from December 2007 to June 2010 at the ANTARES underwater neutrino telescope in the deep NW Mediterranean Sea, jointly with synchronous hydrological records. This is the longest continuous time-series of deep-sea bioluminescence ever recorded. Our record reveals several weeks long, seasonal bioluminescence blooms with light intensity up to two orders of magnitude higher than background values, which correlate to changes in the properties of deep waters. Such changes are triggered by the winter cooling and evaporation experienced by the upper ocean layer in the Gulf of Lion that leads to the formation and subsequent sinking of dense water through a process known as "open-sea convection". It episodically renews the deep water of the study area and conveys fresh organic matter that fuels the deep ecosystems. Luminous bacteria most likely are the main contributors to the observed deep-sea bioluminescence blooms. Our observations demonstrate a consistent and rapid connection between deep open-sea convection and bathypelagic biological activity, as expressed by bioluminescence. In a setting where dense water formation events are likely to decline under global warming scenarios enhancing ocean stratification, in situ observatories become essential as environmental sentinels for the monitoring and understanding of deep-sea ecosystem shifts.

  3. Deep-sea bioluminescence blooms after dense water formation at the ocean surface.

    Directory of Open Access Journals (Sweden)

    Christian Tamburini

    Full Text Available The deep ocean is the largest and least known ecosystem on Earth. It hosts numerous pelagic organisms, most of which are able to emit light. Here we present a unique data set consisting of a 2.5-year long record of light emission by deep-sea pelagic organisms, measured from December 2007 to June 2010 at the ANTARES underwater neutrino telescope in the deep NW Mediterranean Sea, jointly with synchronous hydrological records. This is the longest continuous time-series of deep-sea bioluminescence ever recorded. Our record reveals several weeks long, seasonal bioluminescence blooms with light intensity up to two orders of magnitude higher than background values, which correlate to changes in the properties of deep waters. Such changes are triggered by the winter cooling and evaporation experienced by the upper ocean layer in the Gulf of Lion that leads to the formation and subsequent sinking of dense water through a process known as "open-sea convection". It episodically renews the deep water of the study area and conveys fresh organic matter that fuels the deep ecosystems. Luminous bacteria most likely are the main contributors to the observed deep-sea bioluminescence blooms. Our observations demonstrate a consistent and rapid connection between deep open-sea convection and bathypelagic biological activity, as expressed by bioluminescence. In a setting where dense water formation events are likely to decline under global warming scenarios enhancing ocean stratification, in situ observatories become essential as environmental sentinels for the monitoring and understanding of deep-sea ecosystem shifts.

  4. Phytoplankton blooms in estuarine and coastal waters: Seasonal patterns and key species

    Science.gov (United States)

    Carstensen, Jacob; Klais, Riina; Cloern, James E.

    2015-01-01

    Phytoplankton blooms are dynamic phenomena of great importance to the functioning of estuarine and coastal ecosystems. We analysed a unique (large) collection of phytoplankton monitoring data covering 86 coastal sites distributed over eight regions in North America and Europe, with the aim of investigating common patterns in the seasonal timing and species composition of the blooms. The spring bloom was the most common seasonal pattern across all regions, typically occurring early (February–March) at lower latitudes and later (April–May) at higher latitudes. Bloom frequency, defined as the probability of unusually high biomass, ranged from 5 to 35% between sites and followed no consistent patterns across gradients of latitude, temperature, salinity, water depth, stratification, tidal amplitude or nutrient concentrations. Blooms were mostly dominated by a single species, typically diatoms (58% of the blooms) and dinoflagellates (19%). Diatom-dominated spring blooms were a common feature in most systems, although dinoflagellate spring blooms were also observed in the Baltic Sea. Blooms dominated by chlorophytes and cyanobacteria were only common in low salinity waters and occurred mostly at higher temperatures. Key bloom species across the eight regions included the diatoms Cerataulina pelagica and Dactyliosolen fragilissimus and dinoflagellates Heterocapsa triquetra and Prorocentrum cordatum. Other frequent bloom-forming taxa were diatom genera Chaetoceros, Coscinodiscus, Skeletonema, and Thalassiosira. Our meta-analysis shows that these 86 estuarine-coastal sites function as diatom-producing systems, the timing of that production varies widely, and that bloom frequency is not associated with environmental factors measured in monitoring programs. We end with a perspective on the limitations of conclusions derived from meta-analyses of phytoplankton time series, and the grand challenges remaining to understand the wide range of bloom patterns and

  5. Primary marine aerosol emissions from the Mediterranean Sea during pre-bloom and oligotrophic conditions: correlations to seawater chlorophyll a from a mesocosm study

    Science.gov (United States)

    Schwier, A. N.; Rose, C.; Asmi, E.; Ebling, A. M.; Landing, W. M.; Marro, S.; Pedrotti, M.-L.; Sallon, A.; Iuculano, F.; Agusti, S.; Tsiola, A.; Pitta, P.; Louis, J.; Guieu, C.; Gazeau, F.; Sellegri, K.

    2015-07-01

    The effect of ocean acidification and changing water conditions on primary (and secondary) marine aerosol emissions is not well understood on a regional or a global scale. To investigate this effect as well as the indirect effect on aerosol that changing biogeochemical parameters can have, ~ 52 m3 pelagic mesocosms were deployed for several weeks in the Mediterranean Sea during both winter pre-bloom and summer oligotrophic conditions and were subjected to various levels of CO2 to simulate the conditions foreseen in this region for the coming decades. After seawater sampling, primary bubble-bursting aerosol experiments were performed using a plunging water jet system to test both chemical and physical aerosol parameters (10-400 nm). Comparing results obtained during pre-bloom and oligotrophic conditions, we find the same four log-normal modal diameters (18.5 ± 0.6, 37.5 ± 1.4, 91.5 ± 2.0, 260 ± 3.2 nm) describing the aerosol size distribution during both campaigns, yet pre-bloom conditions significantly increased the number fraction of the second (Aitken) mode, with an amplitude correlated to virus-like particles, heterotrophic prokaryotes, TEPs (transparent exopolymeric particles), chlorophyll a and other pigments. Organic fractions determined from kappa closure calculations for the diameter, Dp ~ 50 nm, were much larger during the pre-bloom period (64 %) than during the oligotrophic period (38 %), and the organic fraction decreased as the particle size increased. Combining data from both campaigns together, strong positive correlations were found between the organic fraction of the aerosol and chlorophyll a concentrations, heterotrophic and autotrophic bacteria abundance, and dissolved organic carbon (DOC) concentrations. As a consequence of the changes in the organic fraction and the size distributions between pre-bloom and oligotrophic periods, we find that the ratio of cloud condensation nuclei (CCN) to condensation nuclei (CN) slightly decreased during the

  6. Purine Biosynthesis Metabolically Constrains Intracellular Survival of Uropathogenic Escherichia coli.

    Science.gov (United States)

    Shaffer, Carrie L; Zhang, Ellisa W; Dudley, Anne G; Dixon, Beverly R E A; Guckes, Kirsten R; Breland, Erin J; Floyd, Kyle A; Casella, Daniel P; Algood, Holly M Scott; Clayton, Douglass B; Hadjifrangiskou, Maria

    2017-01-01

    The ability to de novo synthesize purines has been associated with the intracellular survival of multiple bacterial pathogens. Uropathogenic Escherichia coli (UPEC), the predominant cause of urinary tract infections, undergoes a transient intracellular lifestyle during which bacteria clonally expand into multicellular bacterial communities within the cytoplasm of bladder epithelial cells. Here, we characterized the contribution of the conserved de novo purine biosynthesis-associated locus cvpA-purF to UPEC pathogenesis. Deletion of cvpA-purF, or of purF alone, abolished de novo purine biosynthesis but did not impact bacterial adherence properties in vitro or in the bladder lumen. However, upon internalization by bladder epithelial cells, UPEC deficient in de novo purine biosynthesis was unable to expand into intracytoplasmic bacterial communities over time, unless it was extrachromosomally complemented. These findings indicate that UPEC is deprived of purine nucleotides within the intracellular niche and relies on de novo purine synthesis to meet this metabolic requirement. Copyright © 2016 American Society for Microbiology.

  7. Intracellular Hg(0) Oxidation in Desulfovibrio desulfuricans ND132.

    Science.gov (United States)

    Wang, Yuwei; Schaefer, Jeffra K; Mishra, Bhoopesh; Yee, Nathan

    2016-10-03

    The disposal of elemental mercury (Hg(0)) wastes in mining and manufacturing areas has caused serious soil and groundwater contamination issues. Under anoxic conditions, certain anaerobic bacteria can oxidize dissolved elemental mercury and convert the oxidized Hg to neurotoxic methylmercury. In this study, we conducted experiments with the Hg-methylating bacterium Desulfovibrio desulfuricans ND132 to elucidate the role of cellular thiols in anaerobic Hg(0) oxidation. The concentrations of cell-surface and intracellular thiols were measured, and specific fractions of D. desulfuricans ND132 were examined for Hg(0) oxidation activity and analyzed with extended X-ray absorption fine structure (EXAFS) spectroscopy. The experimental data indicate that intracellular thiol concentrations are approximately six times higher than those of the cell wall. Cells reacted with a thiol-blocking reagent were severely impaired in Hg(0) oxidation activity. Spheroplasts lacking cell walls rapidly oxidized Hg(0) to Hg(II), while cell wall fragments exhibited low reactivity toward Hg(0). EXAFS analysis of spheroplast samples revealed that multiple different forms of Hg-thiols are produced by the Hg(0) oxidation reaction and that the local coordination environment of the oxidized Hg changes with reaction time. The results of this study indicate that Hg(0) oxidation in D. desulfuricans ND132 is an intracellular process that occurs by reaction with thiol-containing molecules.

  8. Bacteriomimetic invasin-functionalized nanocarriers for intracellular delivery.

    Science.gov (United States)

    Labouta, Hagar Ibrahim; Menina, Sara; Kochut, Annika; Gordon, Sarah; Geyer, Rebecca; Dersch, Petra; Lehr, Claus-Michael

    2015-12-28

    Intracellular bacteria invade mammalian cells to establish an infectious niche. The current work models adhesion and subsequent internalization strategy of pathogenic bacteria into mammalian cells to design a bacteriomimetic bioinvasive delivery system. We report on the surface functionalization of liposomes with a C-terminal fragment of invasin (InvA497), an invasion factor in the outer membrane of Yersinia pseudotuberculosis. InvA497-functionalized liposomes adhere to mammalian epithelial HEp-2 cell line at different infection stages with a significantly higher efficiency than liposomes functionalized with bovine serum albumin. Covalent attachment of InvA497 results in higher cellular adhesion than liposomes with physically adsorbed InvA497 with non-specific surface protein alignment. Uptake studies in HEp-2 cells indicate active internalization of InvA497-functionalized liposomes via β1-integrin receptor-mediated uptake mechanism mimicking the natural invasion strategy of Y. pseudotuberculosis. Uptake studies in Caco-2 cells at different polarization states demonstrate specific targeting of the InvA497-functionalized liposomes to less polarized cells reflecting the status of inflamed cells. Moreover, when loaded with the anti-infective agent gentamicin and applied to HEp-2 cells infected with Y. pseudotuberculosis, InvA497-functionalized liposomes are able to significantly reduce the infection load relative to non-functionalized drug-loaded liposomes. This indicates a promising application of such a bacteriomimetic system for drug delivery to intracellular compartments. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Intracellular survival of Staphylococcus aureus during persistent infection in the insect Tenebrio molitor.

    Science.gov (United States)

    McGonigle, John E; Purves, Joanne; Rolff, Jens

    2016-06-01

    Survival of bacteria within host cells and tissues presents a challenge to the immune systems of higher organisms. Escape from phagocytic immune cells compounds this issue, as immune cells become potential vehicles for pathogen dissemination. However, the duration of persistence within phagocytes and its contribution to pathogen load has yet to be determined. We investigate the immunological significance of intracellular persistence within the insect model Tenebrio molitor, assessing the extent, duration and location of bacterial recovery during a persistent infection. Relative abundance of Staphylococcus aureus in both intracellular and extracellular fractions was determined over 21 days, and live S. aureus were successfully recovered from both the hemolymph and within phagocytic immune cells across the entire time course. The proportion of bacteria recovered from within phagocytes also increased over time. Our results show that to accurately estimate pathogen load it is vital to account for bacteria persisting within immune cells. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Didymosphenia geminata: Algal blooms in oligotrophic streams and rivers

    Science.gov (United States)

    Sundareshwar, P. V.; Upadhayay, S.; Abessa, M.; Honomichl, S.; Berdanier, B.; Spaulding, S. A.; Sandvik, C.; Trennepohl, A.

    2011-05-01

    In recent decades, the diatom Didymosphenia geminata has emerged as nuisance species in river systems around the world. This periphytic alga forms large “blooms” in temperate streams, presenting a counterintuitive result: the blooms occur primarily in oligotrophic streams and rivers, where phosphorus (P) availability typically limits primary production. The goal of this study is to examine how high algal biomass is formed under low P conditions. We reveal a biogeochemical process by which D. geminata mats concentrate P from flowing waters. First, the mucopolysaccaride stalks of D. geminata adsorb both iron (Fe) and P. Second, enzymatic and bacterial processes interact with Fe to increase the biological availability of P. We propose that a positive feedback between total stalk biomass and high growth rate is created, which results in abundant P for cell division. The affinity of stalks for Fe in association with iron-phosphorus biogeochemistry suggest a resolution to the paradox of algal blooms in oliogotrophic streams and rivers.

  11. Fish Kill Incidents and Harmful Algal Blooms in Omani Waters

    Directory of Open Access Journals (Sweden)

    Hamed Mohammed Al Gheilani

    2011-01-01

    Full Text Available Red tide, one of the harmful algal blooms (HABs is a natural ecological phenomenon and often this event is accompanied by severe impacts on coastal resources, local economies, and public health. The occurrence of red tides has become more frequent in Omani waters in recent years. Some of them caused fish kill, damaged fishery resources and mariculture, threatened the marine environment and the osmosis membranes of desalination plants. However, a number of them have been harmless. The most common dinoflagellate Noctiluca scintillans is associated with the red tide events in Omani waters. Toxic species like Karenia selliformis, Prorocentrum arabianum, and Trichodesmium erythraeum have also been reported recently. Although red tides in Oman have been considered a consequence of upwelling in the summer season (May to September, recent phytoplankton outbreaks in Oman are not restricted to summer. Frequent algal blooms have been reported during winter (December to March. HABs may have contributed to hypoxia and/or other negative ecological impacts.

  12. Oceans and Human Health: Microplastics and Harmful Algal Bloom

    International Nuclear Information System (INIS)

    Sombrito, Elvira Z.

    2015-01-01

    Traditionally the focus of research and concern of environmental studies in the marine system is the impact of human activities in the ocean: the sources, distribution and fate of pollutants resulting from human activities. More recently, there has been recognition of the potential direct impact health can come from eating contaminated seafood, swimming in polluted water, and exposure to toxins from harmful algal blooms. This paper will present two areas of concern that illustrates the fact that the health of the oceans and the health of humans go hand in hand: chemical pollution from plastics in the ocean and harmful alga bloom. The nuclear methodologies than can be useful in these areas will also be introduced. It is hoped that through the recognition of the inter-dependence of the health of both humans and the oceans, efforts will be made to restore and preserve the oceans. (author)

  13. MR imaging of intracellular and extracellular deoxyhemoglobin

    International Nuclear Information System (INIS)

    Janick, P.A.; Grossman, R.I.; Asakura, T.

    1989-01-01

    MR imaging was performed on varying concentrations of intracellular and extracellular deoxyhemoglobin as well as varying proportions of deoxyhemoglobin and oxyhemoglobin in vitro at 1.5T with use of standard spin-echo and gradient-refocused spin sequences. This study indicates that susceptibility-induced T2 shortening occurs over a broad range of intracellular deoxyhemoglobin concentrations (maximal at hematocrits between 20% and 45%), reflecting diffusional effects at the cellular level. T2* gradient-echo imaging enhances the observed hypointensity in images of intracellular deoxyhemoglobin. The characteristic MR appearance of acute hemotomas can be modeled by the behavior of intracellular and extracellular deoxyhemoglobin and oxyhemoglobin

  14. Environmental Chemistry and Chemical Ecology of "Green Tide" Seaweed Blooms.

    Science.gov (United States)

    Van Alstyne, Kathryn L; Nelson, Timothy A; Ridgway, Richard L

    2015-09-01

    Green tides are large growths or accumulations of green seaweeds that have been increasing in magnitude and frequency around the world. Because green tides consist of vast biomasses of algae in a limited area and are often seasonal or episodic, they go through periods of rapid growth in which they take up large amounts of nutrients and dissolved gases and generate bioactive natural products that may be stored in the plants, released into the environment, or broken down during decomposition. As a result of the use and production of inorganic and organic compounds, the algae in these blooms can have detrimental impacts on other organisms. Here, we review some of the effects that green tides have on the chemistry of seawater and the effects of the natural products that they produce. As blooms are developing and expanding, algae in green tides take up inorganic nutrients, such as nitrate and ortho-phosphate, which can limit their availability to other photosynthetic organisms. Their uptake of dissolved inorganic carbon for use in photosynthesis can cause localized spikes in the pH of seawater during the day with concomitant drops in the pH at night when the algae are respiring. Many of the algae that form green-tide blooms produce allelopathic compounds, which are metabolites that affect other species. The best documented allelopathic compounds include dimethylsulfoniopropionate (DMSP), dopamine, and reactive oxygen species (ROS) and their breakdown products. DMSP and dopamine are involved in defenses against herbivores. Dopamine and ROS are released into seawater where they can be allelopathic or toxic to other organisms. Thus, these macroalgal blooms can have harmful effects on nearby organisms by altering concentrations of nutrients and dissolved gas in seawater and by producing and releasing allelopathic or toxic compounds. © The Author 2015. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved

  15. Distribution and recurrence of phytoplankton blooms around South Georgia, Southern Ocean

    Directory of Open Access Journals (Sweden)

    I. Borrione

    2013-01-01

    Full Text Available South Georgia phytoplankton blooms are amongst the largest of the Southern Ocean and are associated with a rich ecosystem and strong atmospheric carbon drawdown. Both aspects depend on the intensity of blooms, but also on their regularity. Here we use data from 12 yr of SeaWiFS (Sea-viewing Wide Field-of-view Sensor ocean colour imagery and calculate the frequency of bloom occurrence (FBO to re-examine spatial and temporal bloom distributions. We find that upstream of the island and outside the borders of the Georgia Basin, blooms occurred in less than 4 out of the 12 yr (FBO < 4. In contrast, FBO was mostly greater than 8 downstream of the island, i.e., to the north and northwest, and in places equal to 12, indicating that blooms occurred every year. The typical bloom area, defined as the region where blooms occurred in at least 8 out of the 12 yr, covers the entire Georgia Basin and the northern shelf of the island. The time series of surface chlorophyll a (Chl a concentrations averaged over the typical bloom area shows that phytoplankton blooms occurred in every year between September 1997 and September 2010, and that Chl a values followed a clear seasonal cycle, with concentration peaks around December followed in many years by a second peak during late austral summer or early autumn, suggesting a bi-modal bloom pattern. The bloom regularity we describe here is in contrast with results of Park et al. (2010 who used a significantly different study area including regions that almost never exhibit bloom conditions.

  16. The genome sequence of Rickettsia felis identifies the first putative conjugative plasmid in an obligate intracellular parasite.

    OpenAIRE

    Hiroyuki Ogata; Patricia Renesto; Stéphane Audic; Catherine Robert; Guillaume Blanc; Pierre-Edouard Fournier; Hugues Parinello; Jean-Michel Claverie; Didier Raoult

    2005-01-01

    We sequenced the genome of Rickettsia felis, a flea-associated obligate intracellular alpha-proteobacterium causing spotted fever in humans. Besides a circular chromosome of 1,485,148 bp, R. felis exhibits the first putative conjugative plasmid identified among obligate intracellular bacteria. This plasmid is found in a short (39,263 bp) and a long (62,829 bp) form. R. felis contrasts with previously sequenced Rickettsia in terms of many other features, including a number of transposases, sev...

  17. Petal Thicknesses and Shape Transformations in Blooming Lilies

    Energy Technology Data Exchange (ETDEWEB)

    Portet, Thomas; Holmes, Peter N.; Bowden, Mark E.; Stephens, Sean A.; Varga, Tamas; Keller, Sarah L.

    2013-01-29

    During blooming, flower petals undergo significant shape changes. For lilies, various different mechanisms responsible for the change have been suggested [1,2]. One is that cell growth along the edge of a petal, or, more generally, a tepal, drives a transition from a cup shape (within a bud) to a saddle shape (within a bloom). This mechanism has been previously considered for tepals modeled as shallow elliptical shells whose thickness from the center, t, falls off at least as fast as t = t0 (1 - x2/a2 - y2/b2 ) [1]. Here t0 is the maximum thickness of the shell, a and b are the semimajor and semiminoraxes, x and y are the coordinates along the longitudinal and lateral axes. By measuring tepal thicknesses from images collected by x-ray tomography of intact buds and by photography of microtomed buds, we find that this condition is indeed met for both Lilium casablanca and Lilium lancifolium. [1] Liang and Mahadevan. Growth, geometry, and mechanics of a blooming lily.

  18. Didymosphenia geminata: Algal blooms in oligotrophic streams and rivers

    Science.gov (United States)

    Sundareshwar, P.V.; Upadhayay, S.; Abessa, M.; Honomichl, S.; Berdanier, B.; Spaulding, S.A.; Sandvik, C.; Trennepohl, A.

    2011-01-01

    In recent decades, the diatom Didymosphenia geminata has emerged as nuisance species in river systems around the world. This periphytic alga forms large "blooms" in temperate streams, presenting a counterintuitive result: the blooms occur primarily in oligotrophic streams and rivers, where phosphorus (P) availability typically limits primary production. The goal of this study is to examine how high algal biomass is formed under low P conditions. We reveal a biogeochemical process by which D. geminata mats concentrate P from flowing waters. First, the mucopolysaccaride stalks of D. geminata adsorb both iron (Fe) and P. Second, enzymatic and bacterial processes interact with Fe to increase the biological availability of P. We propose that a positive feedback between total stalk biomass and high growth rate is created, which results in abundant P for cell division. The affinity of stalks for Fe in association with iron-phosphorus biogeochemistry suggest a resolution to the paradox of algal blooms in oliogotrophic streams and rivers. Copyright 2011 by the American Geophysical Union.

  19. Cyanobacterial bloom in the world largest freshwater lake Baikal

    Science.gov (United States)

    Namsaraev, Zorigto; Melnikova, Anna; Ivanov, Vasiliy; Komova, Anastasia; Teslyuk, Anton

    2018-02-01

    Lake Baikal is a UNESCO World Heritage Site and holds 20% of the world’s freshwater reserves. On July 26, 2016, a cyanobacterial bloom of a green colour a few kilometers in size with a bad odor was discovered by local people in the Barguzinsky Bay on the eastern shore of Lake Baikal. Our study showed very high concentration of chlorophyll a (41.7 g/m3) in the sample of bloom. We found that the bloom was dominated by a nitrogen-fixing heterocystous cyanobacteria of the genus Dolichospermum. The mass accumulation of cyanobacteria in the lake water with an extremely high chlorophyll a concentration can be explained by a combination of several factors: the discharge of biologicaly-available nutrients, including phosphorus, into the water of Lake Baikal; low wind speed and weak water mixing; buoyant cyanobacterial cells on the lake surface, which drifted towards the eastern coast, where the maximum concentration of chlorophyll a was recorded. In the center of the Barguzinsky Bay and in the open part of Lake Baikal, according to satellite data, the chlorophyll a concentration is several orders of magnitude lower than at the shoreline.

  20. The history of cyanobacterial blooms in the Baltic Sea.

    Science.gov (United States)

    Finni, T; Kononen, K; Olsonen, R; Wallström, K

    2001-08-01

    Long-term information on possible changes in cyanobacterial blooms in the Baltic Sea, formed mainly by Nodularia spumigena and Aphanizomenon sp., was sought in published records in historical (years 1887-1938) and modern (years 1974-1998) phytoplankton data sets. Old and new sampling methods and fixatives were tested to improve the comparison of data that had been collected and analyzed in different ways. A hundred years ago, plankton was mainly of interest as a source of fish food; eutrophication problems were only locally reported from the coast, mainly in southern haffs and the receiving waters of larger cities. There were few recordings of open-sea blooms before World War II. Abundances of Nodularia spumigena and Aphanizomenon sp. were low in the old material, and 137 summer samples from 1887-1938 showed no peak abundance. High abundances are common in the new material, and the range of the numbers of both taxa has increased markedly relative to the old material. Since the 1960s, cyanobacterial blooms have been common in the open sea in both the Baltic proper and the Gulf of Finland, indicating high availability of nutrients.

  1. Weather during bloom affects pollination and yield of highbush blueberry.

    Science.gov (United States)

    Tuell, Julianna K; Isaacs, Rufus

    2010-06-01

    Weather plays an important role in spring-blooming fruit crops due to the combined effects on bee activity, flower opening, pollen germination, and fertilization. To determine the effects of weather on highbush blueberry, Vaccinium corymbosum L., productivity, we monitored bee activity and compared fruit set, weight, and seed number in a field stocked with honey bees, Apis mellifera L., and common eastern bumble bees, Bombus impatiens (Cresson). Flowers were subjected to one of five treatments during bloom: enclosed, open, open during poor weather only, open during good weather only, or open during poor and good weather. Fewer bees of all types were observed foraging and fewer pollen foragers returned to colonies during poor weather than during good weather. There were also changes in foraging community composition: honey bees dominated during good weather, whereas bumble bees dominated during poor weather. Berries from flowers exposed only during poor weather had higher fruit set in 1 yr and higher berry weight in the other year compared with enclosed clusters. In both years, clusters exposed only during good weather had > 5 times as many mature seeds, weighed twice as much, and had double the fruit set of those not exposed. No significant increase over flowers exposed during good weather was observed when clusters were exposed during good and poor weather. Our results are discussed in terms of the role of weather during bloom on the contribution of bees adapted to foraging during cool conditions.

  2. Peculiarities of the Woody Plants Re-Bloom

    Directory of Open Access Journals (Sweden)

    Opalko Olga Anatolievna

    2015-09-01

    Full Text Available The data of literary sources concerning the bloom of angiosperm plants and deviation in the development of a flower and inflorescence, in particular untimely flowering, was generalized; our observation results of some peculiarities of re-bloom of woody plants in the National Dendrological Park “Sofiyivka” of NAS of Ukraine (NDP “Sofiyivka” were discussed. The flowering process was formed during a long-term evolution of a propagation system of angiosperm plants as a basis of fertilization and further fruit and seed development. As a result of vernalization and photoperiodism reactions, flowering (under regular conditions occurs in the most favorable period for pollination and fertilization of every plant. However, various deviations, in particular, the untimely (most frequently double, sometimes three- and four-fold flowering occurs in this perfect process of generative organ formation of angiosperm plants. An increased number of reports about re-bloom (at the end of summer – at the beginning of fall of the representatives of various woody plant species whose flowers usually blossom in May-June prompts the analysis of the available information concerning the mechanisms of flowering and the causes which lead to deviation of flowering processes. Flowering of the woody plant representatives of the collection fund of the NDP “Sofiyivka” was studied; statistics about re-bloom in different cities of Ukraine were monitored. The classification of re-bloom facts was carried out according to V.L. Vitkovskiy (1984. Although this classification has mostly a stated nature, it was good enough when being formulated and, with certain conditions, it can be applied nowadays. Accordingly, using this classification, abnormal cases can include facts of early summer-fall flowering and early winter flowering. A late spring flowering can be adaptive response of damaged plants to exogenous stresses, due to which the probability of sexual propagation remains

  3. Connecting Florida Bay algal blooms to freshwater nutrient sources

    Science.gov (United States)

    Blakey, T.; Melesse, A. M.

    2013-12-01

    In this study, monthly water quality data collected in the Everglades by the Southeast Environmental Research Center (SERC) and the South Florida Water Management District (SFWMD) from 1991 to 2008 at 28 sampling stations distributed across Florida Bay was analyzed within the context of local geomorphology and seasonal wind and current regimes in order to evaluate the feasibility of the various purported nutrient sources for reoccurring algal blooms. The in situ chlorophyll-a (chl-a) measurements from the SERC dataset were evaluated as the indicator of algal biomass. Significant differences in average monthly chl-a concentrations at stations indicated a seasonality of algal blooms in the north central and west areas that is not evidenced in stations exhibiting low levels of chl-a throughout the typical year. Tukey's pairwise comparisons of monthly chl-a indicated, at the 95% confidence level, peak algal biomass occurs in October and November at the end of the wet season with minimums occurring between February and August depending on the location of the station. By month comparison of chl-a levels across stations suggest seasonal trends in the geographic focus and extent of blooms. Significant differences from Tukey's pairwise comparisons at the 95% confidence level showed stations to the west as having higher levels of chl-a in March through May with north central stations dominating from June to January. The month of February shows no significant difference in chl-a levels across this area. The results support hypotheses centering on a western source of nutrients that are delivered to the bay over the course of the rainy season. Mapping water quality sampling station locations on top of the bathymetry of Florida Bay illustrates the importance of considering coastal morphology in explaining trends in estuarine algal blooms. Coastal geomorphology along with seasonal changes in the direction of winds and magnitude of rains are demonstrated to be the predominant

  4. A coagulation-powdered activated carbon-ultrafiltration - Multiple barrier approach for removing toxins from two Australian cyanobacterial blooms

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, Mike B., E-mail: mike.dixon@sawater.com.au [Australian Water Quality Centre, SA Water Corporation, GPO Box 1751, Adelaide, SA, 5001 (Australia); School of Chemical Engineering, University of Adelaide, SA 5005 (Australia); Richard, Yann [School of Chemistry, Physics and Electronics, 48 Blvd du 11 Nov 1918, BP 2077-69616, Villeurbanne Cedex (France); Ho, Lionel [Australian Water Quality Centre, SA Water Corporation, GPO Box 1751, Adelaide, SA, 5001 (Australia); School of Earth and Environmental Sciences, University of Adelaide, SA 5005 (Australia); Chow, Christopher W.K. [Australian Water Quality Centre, SA Water Corporation, GPO Box 1751, Adelaide, SA, 5001 (Australia); O' Neill, Brian K. [School of Chemical Engineering, University of Adelaide, SA 5005 (Australia); Newcombe, Gayle [Australian Water Quality Centre, SA Water Corporation, GPO Box 1751, Adelaide, SA, 5001 (Australia)

    2011-02-28

    Cyanobacteria are a major problem for the world wide water industry as they can produce metabolites toxic to humans in addition to taste and odour compounds that make drinking water aesthetically displeasing. Removal of cyanobacterial toxins from drinking water is important to avoid serious illness in consumers. This objective can be confidently achieved through the application of the multiple barrier approach to drinking water quality and safety. In this study the use of a multiple barrier approach incorporating coagulation, powdered activated carbon (PAC) and ultrafiltration (UF) was investigated for the removal of intracellular and extracellular cyanobacterial toxins from two naturally occurring blooms in South Australia. Also investigated was the impact of these treatments on the UF flux. In this multibarrier approach, coagulation was used to remove the cells and thus the intracellular toxin while PAC was used for extracellular toxin adsorption and finally the UF was used for floc, PAC and cell removal. Cyanobacterial cells were completely removed using the UF membrane alone and when used in conjunction with coagulation. Extracellular toxins were removed to varying degrees by PAC addition. UF flux deteriorated dramatically during a trial with a very high cell concentration; however, the flux was improved by coagulation and PAC addition.

  5. Intracellular Polyamines Enhance Astrocytic Coupling

    Science.gov (United States)

    Benedikt, Jan; Inyushin, Mikhail; Kucheryavykh, Yuriy V.; Rivera, Yomarie; Kucheryavykh, Lilia Y.; Nichols, Colin G.; Eaton, Misty J.; Skatchkov, Serguei N.

    2013-01-01

    Spermine (SPM) and spermidine (SPD), endogenous polyamines (PA) with the ability to modulate various ion channels and receptors in the brain, exert neuroprotective, antidepressant, antioxidant and other effects in vivo such as increasing longevity. These PA are preferably accumulated in astrocytes, and we hypothesized that SPM increases glial intercellular communication by interacting with glial gap junctions. Results obtained in situ, using Lucifer yellow propagation in the astrocytic syncitium of 21–25 day old rat CA1 hippocampal slices, showed reduced coupling when astrocytes were dialyzed with standard intracellular solutions (ICS) without SPM. However, there was a robust increase in the spreading of Lucifer yellow via gap junctions to neighboring astrocytes when the cells were patched with ICS containing 1 mM SPM; a physiological concentration in glia. Lucifer yellow propagation was inhibited by gap junction blockers. Our findings show that the glial syncitium propagates SPM via gap junctions and further suggest a new role of polyamines in the regulation of the astroglial network in both normal and pathological conditions. PMID:23076119

  6. Intracellular Bacterial Communities: A Potential Etiology for Chronic Lower Urinary Tract Symptoms.

    Science.gov (United States)

    Scott, Victoria C S; Haake, David A; Churchill, Bernard M; Justice, Sheryl S; Kim, Ja-Hong

    2015-09-01

    Patients with persistent lower urinary tract symptoms and negative urine cultures are often difficult to treat. Infection may go undetected in these patients because the concentrations of bacteria in their urine are beneath the threshold of standard urine culture techniques. Empiric treatment may result in temporary relief, followed by recurrent symptoms. Occult and recurrent urinary tract infection may be due to both invasion of the bladder wall by uropathogenic Escherichia coli and the formation of biofilm-like intracellular bacterial communities. This review examines emerging evidence for a role of intracellular bacterial communities in human infection. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. Critical Examination of a Revision of Bloom's Taxonomy for the Development of Art Education Curriculum

    OpenAIRE

    中村, 和世; 大和, 浩子; 中島, 敦夫; 吉川, 和生

    2011-01-01

    This paper is aimed at developing Art Education Taxonomy Table through critically examining a revision of Bloom's Taxonomy of Educational Objectives contrived by Anderson and Krathwohl. First, the overview of the history of Bloom's Taxonomy is provided in relation to art education. Second, the influence of Bloom's theory of educational evaluation and Taxonomy on the classroom practice of art education in Japan is discussed. Third, aiming at using for the development of art education curriculu...

  8. Metagenomic analysis reveals symbiotic relationship among bacteria in Microcystis-dominated community

    Directory of Open Access Journals (Sweden)

    Meili eXie

    2016-02-01

    Full Text Available Microcystis bloom, a cyanobacterial mass occurrence often found in eutrophicated water bodies, is one of the most serious threats to freshwater ecosystems worldwide. In nature, Microcystis forms aggregates or colonies that contain heterotrophic bacteria. The Microcystis-bacteria colonies were persistent even when they were maintained in lab culture for a long period. The relationship between Microcystis and the associated bacteria was investigated by a metagenomic approach in this study. We developed a visualization-guided method of binning for genome assembly after total colony DNA sequencing. We found that the method was effective in grouping sequences and it did not require reference genome sequence. Individual genomes of the colony bacteria were obtained and they provided valuable insights into microbial community structures. Analysis of metabolic pathways based on these genomes revealed that while all heterotrophic bacteria were dependent upon Microcystis for carbon and energy, Vitamin B12 biosynthesis, which is required for growth by Microcystis, was accomplished in a cooperative fashion among the bacteria. Our analysis also suggests that individual bacteria in the colony community contributed a complete pathway for degradation of benzoate, which is inhibitory to the cyanobacterial growth, and its ecological implication for Microcystis bloom is discussed.

  9. Technology and Bloom's Taxonomy: Tools to Facilitate Higher-Level Learning in Chemistry

    National Research Council Canada - National Science Library

    Morgan, Matthew

    1997-01-01

    This research project ties together chemistry data acquisition technology, introductory chemistry laboratory experiments, and Bloom's Taxonomy of Educational Objectives into a unified learning model...

  10. Health risk assessment standards of cyanobacteria bloom occurrence in bathing sites

    Directory of Open Access Journals (Sweden)

    Agnieszka Stankiewicz

    2011-03-01

    Full Text Available Threat for human health appears during a massive cyanobacteria bloom in potable water used for human consumption or in basins used for recreational purposes. General health risk assessment standards and preventive measures to be taken by sanitation service were presented in scope of: – evaluation of cyanobacteria bloom occurrence in bathing sites / water bodies, – procedures in case of cyanobacteria bloom, including health risk assessment and decision making process to protect users’ health at bathing sites, – preventive measures, to be taken in case of cyanobacteria bloom occurrence in bathing sites and basins, where bathing sites are located.

  11. Episodic upwelling and dust deposition as bloom triggers in low-nutrient, low-chlorophyll regions

    Science.gov (United States)

    Calil, Paulo H. R.; Doney, Scott C.; Yumimoto, Keiya; Eguchi, Kenta; Takemura, Toshihiko

    2011-06-01

    Summertime phytoplankton blooms in the oligotrophic North Pacific Ocean are supported by N2-fixing organisms that relieve the system of nitrate limitation. Phosphate and iron, however, limit their growth and need to be supplied for these organisms to thrive. We analyze two recent blooms in the region whose differences provide insight into their possible formation mechanisms. In 2008, a typical late summer bloom, with sporadic patches of higher-chlorophyll concentration, occurred near the island chain and the subtropical front. In 2010, an unusually large, contiguous bloom was observed in the western oligotrophic North Pacific, a region where blooms seldom, if ever, occur. Streaks of high chlorophyll in 2008 coincide with surface temperature fronts and regions of large horizontal stretching, as detected by Lagrangian diagnostics. Such regions are prone to the generation of vertical velocities via frontogenesis. Horizontal transport from upwelling regions or iron-rich island sediments is also important for the redistribution of nutrients. In the case of the 2010 bloom, we use a global aerosol transport model as well as space-borne lidar observations to argue that atmospheric dust deposition events prior to the bloom provided the necessary nutrient conditions for the growth of N2-fixing organisms. As sea surface temperature increased in the region, chlorophyll values increased significantly, showing that this bloom was likely a consequence of prior enrichment and that temperature is a key factor in bloom development in this important biome.

  12. Non-coding RNA regulation in pathogenic bacteria located inside eukaryotic cells.

    Science.gov (United States)

    Ortega, Alvaro D; Quereda, Juan J; Pucciarelli, M Graciela; García-del Portillo, Francisco

    2014-01-01

    Intracellular bacterial pathogens have evolved distinct lifestyles inside eukaryotic cells. Some pathogens coexist with the infected cell in an obligate intracellular state, whereas others transit between the extracellular and intracellular environment. Adaptation to these intracellular lifestyles is regulated in both space and time. Non-coding small RNAs (sRNAs) are post-transcriptional regulatory molecules that fine-tune important processes in bacterial physiology including cell envelope architecture, intermediate metabolism, bacterial communication, biofilm formation, and virulence. Recent studies have shown production of defined sRNA species by intracellular bacteria located inside eukaryotic cells. The molecules targeted by these sRNAs and their expression dynamics along the intracellular infection cycle remain, however, poorly characterized. Technical difficulties linked to the isolation of "intact" intracellular bacteria from infected host cells might explain why sRNA regulation in these specialized pathogens is still a largely unexplored field. Transition from the extracellular to the intracellular lifestyle provides an ideal scenario in which regulatory sRNAs are intended to participate; so much work must be done in this direction. This review focuses on sRNAs expressed by intracellular bacterial pathogens during the infection of eukaryotic cells, strategies used with these pathogens to identify sRNAs required for virulence, and the experimental technical challenges associated to this type of studies. We also discuss varied techniques for their potential application to study RNA regulation in intracellular bacterial infections.

  13. Brucella abortus nicotinamidase (PncA) contributes to its intracellular replication and infectivity in mice.

    Science.gov (United States)

    Kim, Suk; Kurokawa, Daisuke; Watanabe, Kenta; Makino, Sou-Ichi; Shirahata, Toshikazu; Watarai, Masahisa

    2004-05-15

    Brucella spp. are facultative intracellular pathogens that have the ability to survive and multiply in professional and non-professional phagocytes, and cause abortion in domestic animals and undulant fever in humans. The mechanism and factors of virulence are not fully understood. Nicotinamidase/pyrazinamidase mutant (pncA mutant) of Brucella abortus failed to replicate in HeLa cells, and showed a lower rate of intracellular replication than that of wild-type strain in macrophages. Addition of nicotinic acid, but not nicotinamide, into medium supported intracellular replication of pncA mutant in HeLa cells and macrophages. The pncA mutant was not co-localizing with either late endosomes or lysosomes. The B. abortus virB4 mutant was completely cleared from the spleens of mice after 4 weeks, while the pncA mutant showed a 1.5-log reduction of the number of bacteria isolated from spleens after 10 weeks. Although pncA mutant showed reduced virulence in mice and defective intracellular replication, its ability to confer protection against the virulent B. abortus strain 544 was fully retained. These results suggest that PncA does not contribute to intracellular trafficking of B. abortus, but contributes to utilization of nutrients required for intracellular growth. Our results indicate that detailed characterizations of the pncA mutant may help the improvement of currently available live vaccines. Copyright 2004 Federation of European Microbiological Societies

  14. Intracellular calcium homeostasis and signaling.

    Science.gov (United States)

    Brini, Marisa; Calì, Tito; Ottolini, Denis; Carafoli, Ernesto

    2013-01-01

    Ca(2+) is a universal carrier of biological information: it controls cell life from its origin at fertilization to its end in the process of programmed cell death. Ca(2+) is a conventional diffusible second messenger released inside cells by the interaction of first messengers with plasma membrane receptors. However, it can also penetrate directly into cells to deliver information without the intermediation of first or second messengers. Even more distinctively, Ca(2+) can act as a first messenger, by interacting with a plasma membrane receptor to set in motion intracellular signaling pathways that involve Ca(2+) itself. Perhaps the most distinctive property of the Ca(2+) signal is its ambivalence: while essential to the correct functioning of cells, Ca(2+) becomes an agent that mediates cell distress, or even (toxic) cell death, if its concentration and movements inside cells are not carefully tuned. Ca(2+) is controlled by reversible complexation to specific proteins, which could be pure Ca(2+) buffers, or which, in addition to buffering Ca(2+), also decode its signal to pass it on to targets. The most important actors in the buffering of cell Ca(2+) are proteins that transport it across the plasma membrane and the membrane of the organelles: some have high Ca(2+) affinity and low transport capacity (e.g., Ca(2+) pumps), others have opposite properties (e.g., the Ca(2+) uptake system of mitochondria). Between the initial event of fertilization, and the terminal event of programmed cell death, the Ca(2+) signal regulates the most important activities of the cell, from the expression of genes, to heart and muscle contraction and other motility processes, to diverse metabolic pathways involved in the generation of cell fuels.

  15. Chytrid parasitism facilitates trophic transfer between bloom-forming cyanobacteria and zooplankton (Daphnia).

    Science.gov (United States)

    Agha, Ramsy; Saebelfeld, Manja; Manthey, Christin; Rohrlack, Thomas; Wolinska, Justyna

    2016-10-13

    Parasites are rarely included in food web studies, although they can strongly alter trophic interactions. In aquatic ecosystems, poorly grazed cyanobacteria often dominate phytoplankton communities, leading to the decoupling of primary and secondary production. Here, we addressed the interface between predator-prey and host-parasite interactions by conducting a life-table experiment, in which four Daphnia galeata genotypes were maintained on quantitatively comparable diets consisting of healthy cyanobacteria or cyanobacteria infected by a fungal (chytrid) parasite. In four out of five fitness parameters, at least one Daphnia genotype performed better on parasitised cyanobacteria than in the absence of infection. Further treatments consisting of purified chytrid zoospores and heterotrophic bacteria suspensions established the causes of improved fitness. First, Daphnia feed on chytrid zoospores which trophically upgrade cyanobacterial carbon. Second, an increase in heterotrophic bacterial biomass, promoted by cyanobacterial decay, provides an additional food source for Daphnia. In addition, chytrid infection induces fragmentation of cyanobacterial filaments, which could render cyanobacteria more edible. Our results demonstrate that chytrid parasitism can sustain zooplankton under cyanobacterial bloom conditions, and exemplify the potential of parasites to alter interactions between trophic levels.

  16. The plankton community on Sukkertop and Fylla Banks off West Greenland during a spring bloom and post-bloom period: Hydrography, phytoplankton and protozooplankton

    DEFF Research Database (Denmark)

    Poulsen, Louise K.; Reuss, N.

    2002-01-01

    The plankton community structure was investigated on Sukkertop and Fylla Banks off West Greenland during the spring bloom in May 2000 and the post-bloom period in June 1999. In May a small change in density, clearly illustrated by the profile of potential energy, was sufficient to support a spring...... the phytoplankton community. Heterotrophic biomass was low (5 +/- 1 mg C m(-3)) and an important part was comprised by heterotrophic nanoflagellates (24 +/- 1%). Protozooplankters (heterotrophic dinoflagellates and ciliates) were important grazers of the phytoplankton community in the post-bloom period (estimated...

  17. Peran Pt.bloom Agro Dalam Implementasi Prinsip Fair Trade Di Indonesia (Studi Kasus: Ekspor Beras Organik Pt.bloom Agro Ke Mancanegara Tahun 2008-2015)

    OpenAIRE

    Yealta, Den; Ikhsani, Munadia

    2016-01-01

    This research describes the role of PT.Bloom Agro to do Fair Teade implementation in Indonesia in the case study is the export of PT.Bloom Agros€™s organic rice to foreign country. Fair Trade is the kind of Alternatives trade which populer as donatian movement in 1940. But now in the globalitation era that causes of free trade, fair trade is more popular as alternatives trade movement and as a certification to mark a product has fair tarde guarantee. And in Indonesia PT.Bloom Agro which an ex...

  18. Dormant intracellular salmonella enterica serovar typhimurium discriminates among salmonella pathogenicity island 2 effectors to persist inside fibroblasts

    OpenAIRE

    Núñez Hernández, Cristina; Alonso, Ana; Pucciarelli, María Graciela; Casadesús Pursals, Josep; García del Portillo, Francisco

    2014-01-01

    Salmonella enterica uses effector proteins delivered by type III secretion systems (TTSS) to colonize eukaryotic cells. Recent in vivo studies have shown that intracellular bacteria activate the TTSS encoded by Salmonella pathogenicity island-2 (SPI-2) to restrain growth inside phagocytes. Growth attenuation is also observed in vivo in bacteria colonizing nonphagocytic stromal cells of the intestinal lamina propria and in cultured fibroblasts. SPI-2 is required for survival of nongrowing bact...

  19. Cell biology of anaerobic ammonium-oxidizing bacteria

    NARCIS (Netherlands)

    Niftrik, L.A.M.P. van

    2008-01-01

    Anammox bacteria perform anaerobic ammonium oxidation to dinitrogen gas and belong to the phylum Planctomycetes. Whereas most Prokaryotes consist of one compartment, the cytoplasm bounded by the cytoplasmic membrane and cell wall, the species within this phylum are compartmentalized by intracellular

  20. Quorum sensing-controlled gene expression in lactic acid bacteria

    NARCIS (Netherlands)

    Kuipers, Oscar P.; Ruyter, Pascalle G.G.A. de; Kleerebezem, Michiel; Vos, Willem M. de

    1998-01-01

    Quorum sensing in lactic acid bacteria (LAB) involves peptides that are directly sensed by membrane-located histidine kinases, after which the signal is transmitted to an intracellular response regulator. This regulator in turn activates transcription of target genes, that commonly include the

  1. The Bloom-Gilman duality and leading logarithms

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, C.E. [College of William and Mary, Williamsburg, VA (United States); Mukhopadhyay, N.C. [Rensselaer Polytechnic Inst., Troy, NY (United States)

    1994-04-01

    The existing inclusive electroproduction data base allows the authors a look at the issue of the relative behaviors of background and resonance excitations, a part of the Bloom-Gilman duality. These data lack accuracy at high Q{sup 2} but establish PQCD scaling in the resonance region and even allow the authors a glimpse at the leading logarithmic corrections due to the gluon radiation and its possible quenching at large W and x. These should inspire better quality experimental tests at facilities like CEBAF II.

  2. Unusual Bloom of Tetraselmis sp. in the Valparaiso Bay, Chile

    Science.gov (United States)

    2012-01-01

    base , in accordance with reference (a). , It is the opinion of the author that the subject paper (is __ ) (is not __ ,~><) classified, in...S data base , in ~c,cordelnce with reference (a). It Is the opinion of the author that the subject paper (Is __ ) (is not c/assiHed, in accordance...extinción de la luz, con el fin de describir las condiciones ambientales que se presentaron durante el bloom de enero de 2006. Los datos de radiación

  3. Bloom: A Relationship Visualization Tool for Complex Networks

    Directory of Open Access Journals (Sweden)

    Frank Horsfall

    2010-07-01

    Full Text Available Faced with an ever-increasing capacity to collect and store data, organizations must find a way to make sense of it to their advantage. Methods are required to simplify the data so that it can inform strategic decisions and help solve problems. Visualization tools are becoming increasingly popular since they can display complex relationships in a simple, visual format. This article describes Bloom, a project at Carleton University to develop an open source visualization tool for complex networks and business ecosystems. It provides an overview of the visualization technology used in the project and demonstrates its potential impact through a case study using real-world data.

  4. Phenolic Compounds Characterization and Biological Activities of Citrus aurantium Bloom

    Directory of Open Access Journals (Sweden)

    Armin Oskoueian

    2012-01-01

    Full Text Available Citrus plants are known to possess beneficial biological activities for human health. In addition, ethnopharmacological application of plants is a good tool to explore their bioactivities and active compounds. This research was carried out to evaluate the phenolic and flavonoid analysis, antioxidant properties, anti inflammatory and anti cancer activity of Citrus aurantium bloom. The total phenolics and flavonoids results revealed that methanolic extract contained high total phenolics and flavonoids compared to ethanolic and boiling water extracts. The obtained total phenolics value for methanolic Citrus aurantium bloom extract was 4.55 ± 0.05 mg gallic acid equivalent (GAE/g dry weight (DW, and for total flavonoids it was 3.83 ± 0.05 mg rutin equivalent/g DW. In addition, the RP-HPLC analyses of phenolics and flavonoids indicated the presence of gallic acid, pyrogallol, syringic acid, caffeic acid, rutin, quercetin and naringin as bioactive compounds. The antioxidant activity of Citrus aurantium bloom were examined by the 1,1-diphenyl-2-picryl-hydrazyl (DPPH assay and the ferric reducing/antioxidant potential (FRAP. The free radical scavenging and ferric reducing power activities were higher for the methanolic extract of Citrus aurantium bloom at a concentration of 300 μg/mL, with values of 55.3% and 51.7%, respectively, as compared to the corresponding boiling water and ethanolic extracts, but the activities were lower than those of antioxidant standards such as BHT and α-tocopherol. Furthermore, the anti-inflammatory result of methanolic extract showed appreciable reduction in nitric oxide production of stimulated RAW 264.7 cells at the presence of plant extract. Apart from that, the anticancer activity of the methanolic extract was investigated in vitro against human cancer cell lines (MCF-7; MDA-MB-231, human colon adenocarcinoma (HT-29 and Chang cell as a normal human hepatocyte. The obtained result demonstrated the moderate to

  5. Phenolic compounds characterization and biological activities of Citrus aurantium bloom.

    Science.gov (United States)

    Karimi, Ehsan; Oskoueian, Ehsan; Hendra, Rudi; Oskoueian, Armin; Jaafar, Hawa Z E

    2012-01-30

    Citrus plants are known to possess beneficial biological activities for human health. In addition, ethnopharmacological application of plants is a good tool to explore their bioactivities and active compounds. This research was carried out to evaluate the phenolic and flavonoid analysis, antioxidant properties, anti inflammatory and anti cancer activity of Citrus aurantium bloom. The total phenolics and flavonoids results revealed that methanolic extract contained high total phenolics and flavonoids compared to ethanolic and boiling water extracts. The obtained total phenolics value for methanolic Citrus aurantium bloom extract was 4.55 ± 0.05 mg gallic acid equivalent (GAE)/g dry weight (DW), and for total flavonoids it was 3.83 ± 0.05 mg rutin equivalent/g DW. In addition, the RP-HPLC analyses of phenolics and flavonoids indicated the presence of gallic acid, pyrogallol, syringic acid, caffeic acid, rutin, quercetin and naringin as bioactive compounds. The antioxidant activity of Citrus aurantium bloom were examined by the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) assay and the ferric reducing/antioxidant potential (FRAP). The free radical scavenging and ferric reducing power activities were higher for the methanolic extract of Citrus aurantium bloom at a concentration of 300 μg/mL, with values of 55.3% and 51.7%, respectively, as compared to the corresponding boiling water and ethanolic extracts, but the activities were lower than those of antioxidant standards such as BHT and α-tocopherol. Furthermore, the anti-inflammatory result of methanolic extract showed appreciable reduction in nitric oxide production of stimulated RAW 264.7 cells at the presence of plant extract. Apart from that, the anticancer activity of the methanolic extract was investigated in vitro against human cancer cell lines (MCF-7; MDA-MB-231), human colon adenocarcinoma (HT-29) and Chang cell as a normal human hepatocyte. The obtained result demonstrated the moderate to appreciable

  6. Probing the metabolic water contribution to intracellular water using oxygen isotope ratios of PO4

    Science.gov (United States)

    Li, Hui; Yu, Chan; Wang, Fei; Chang, Sae Jung; Yao, Jun; Blake, Ruth E.

    2016-05-01

    Knowledge of the relative contributions of different water sources to intracellular fluids and body water is important for many fields of study, ranging from animal physiology to paleoclimate. The intracellular fluid environment of cells is challenging to study due to the difficulties of accessing and sampling the contents of intact cells. Previous studies of multicelled organisms, mostly mammals, have estimated body water composition—including metabolic water produced as a byproduct of metabolism—based on indirect measurements of fluids averaged over the whole organism (e.g., blood) combined with modeling calculations. In microbial cells and aquatic organisms, metabolic water is not generally considered to be a significant component of intracellular water, due to the assumed unimpeded diffusion of water across cell membranes. Here we show that the 18O/16O ratio of PO4 in intracellular biomolecules (e.g., DNA) directly reflects the O isotopic composition of intracellular water and thus may serve as a probe allowing direct sampling of the intracellular environment. We present two independent lines of evidence showing a significant contribution of metabolic water to the intracellular water of three environmentally diverse strains of bacteria. Our results indicate that ˜30-40% of O in PO4 comprising DNA/biomass in early stationary phase cells is derived from metabolic water, which bolsters previous results and also further suggests a constant metabolic water value for cells grown under similar conditions. These results suggest that previous studies assuming identical isotopic compositions for intracellular/extracellular water may need to be reconsidered.

  7. Probing the metabolic water contribution to intracellular water using oxygen isotope ratios of PO4

    Science.gov (United States)

    Li, Hui; Yu, Chan; Wang, Fei; Chang, Sae Jung; Yao, Jun; Blake, Ruth E.

    2016-01-01

    Knowledge of the relative contributions of different water sources to intracellular fluids and body water is important for many fields of study, ranging from animal physiology to paleoclimate. The intracellular fluid environment of cells is challenging to study due to the difficulties of accessing and sampling the contents of intact cells. Previous studies of multicelled organisms, mostly mammals, have estimated body water composition—including metabolic water produced as a byproduct of metabolism—based on indirect measurements of fluids averaged over the whole organism (e.g., blood) combined with modeling calculations. In microbial cells and aquatic organisms, metabolic water is not generally considered to be a significant component of intracellular water, due to the assumed unimpeded diffusion of water across cell membranes. Here we show that the 18O/16O ratio of PO4 in intracellular biomolecules (e.g., DNA) directly reflects the O isotopic composition of intracellular water and thus may serve as a probe allowing direct sampling of the intracellular environment. We present two independent lines of evidence showing a significant contribution of metabolic water to the intracellular water of three environmentally diverse strains of bacteria. Our results indicate that ∼30–40% of O in PO4 comprising DNA/biomass in early stationary phase cells is derived from metabolic water, which bolsters previous results and also further suggests a constant metabolic water value for cells grown under similar conditions. These results suggest that previous studies assuming identical isotopic compositions for intracellular/extracellular water may need to be reconsidered. PMID:27170190

  8. Antibiotic susceptibility and intracellular localization of Diplorickettsia massiliensis.

    Science.gov (United States)

    Subramanian, Geetha; Barry, Abdoulaye O; Ghigo, Eric; Raoult, Didier; Mediannikov, Oleg

    2012-02-01

    Diplorickettsia massiliensis is an obligate intracellular bacterium from the Coxiellaceae family recently isolated from Ixodes ricinus ticks. The inhibitory effects of antimicrobial agents were assessed by two different methods, immunofluorescence and Gimenez staining assay. Different markers (EEA1, Lamp-1, Cathepsin D, and LysoTracker Red DND99) were used to reveal the nature of the vacuole containing the bacterium. Ciprofloxacin, levofloxacin, and rifampin had MIC values of 2 lg mL(-1). We found that 4 lg mL(-1) of Doxycycline inhibited the growth of D. massiliensis strain. Surprisingly, D. massiliensis was resistant to chloramphenicol up to the concentration of 64 lg mL(-1). We found that penicillin G, ammonium chloride, gentamycin, omeprazole, bafilomycin A1, and chloroquine were not active against D. massiliensis. Studies performed with markers EEA1, Lamp-1, Cathepsin D, and LysoTracker Red DND99 showed that D. massiliensis is localized within an acidic compartment that is not an early phagosome, but a late phagosome or a phagolysosome. Gimenez staining stays a good method that will work with a very low number of bacteria and can be used to determine the MICs of new therapeutic antibiotics precisely. The resistance profile of D. massiliensis was found to be quite unusual for intracellular Gram-negative bacterium with marked resistance to chloramphenicol. Despite of localization in acidic compartment, pH-neutralizing agents do not significantly inhibit intracellular growth of bacterium. The results of these studies prove that antibiotic resistance does not depend on pH of vacuole. This pH-related mechanism seems not to play a contributing role in the overall resistance of D. massiliensis.

  9. Investigating Internalization and Intracellular Trafficking of GPCRs

    DEFF Research Database (Denmark)

    Foster, Simon R; Bräuner-Osborne, Hans

    2017-01-01

    for signal transduction. One of the major mechanisms for GPCR regulation involves their endocytic trafficking, which serves to internalize the receptors from the plasma membrane and thereby attenuate G protein-dependent signaling. However, there is accumulating evidence to suggest that GPCRs can signal...... independently of G proteins, as well as from intracellular compartments including endosomes. It is in this context that receptor internalization and intracellular trafficking have attracted renewed interest within the GPCR field. In this chapter, we will review the current understanding and methodologies...... that have been used to investigate internalization and intracellular signaling of GPCRs, with a particular focus on emerging real-time techniques. These recent developments have improved our understanding of the complexities of GPCR internalization and intracellular signaling and suggest that the broader...

  10. Nanoparticles for intracellular-targeted drug delivery

    International Nuclear Information System (INIS)

    Paulo, Cristiana S O; Pires das Neves, Ricardo; Ferreira, Lino S

    2011-01-01

    Nanoparticles (NPs) are very promising for the intracellular delivery of anticancer and immunomodulatory drugs, stem cell differentiation biomolecules and cell activity modulators. Although initial studies in the area of intracellular drug delivery have been performed in the delivery of DNA, there is an increasing interest in the use of other molecules to modulate cell activity. Herein, we review the latest advances in the intracellular-targeted delivery of short interference RNA, proteins and small molecules using NPs. In most cases, the drugs act at different cellular organelles and therefore the drug-containing NPs should be directed to precise locations within the cell. This will lead to the desired magnitude and duration of the drug effects. The spatial control in the intracellular delivery might open new avenues to modulate cell activity while avoiding side-effects.

  11. Cephalopods as Vectors of Harmful Algal Bloom Toxins in Marine Food Webs

    Directory of Open Access Journals (Sweden)

    Rui Rosa

    2013-09-01

    Full Text Available Here we summarize the current knowledge on the transfer and accumulation of harmful algal bloom (HAB-related toxins in cephalopods (octopods, cuttlefishes and squids. These mollusks have been reported to accumulate several HAB-toxins, namely domoic acid (DA, and its isomers, saxitoxin (and its derivatives and palytoxin (and palytoxin-like compounds and, therefore, act as HAB-toxin vectors in marine food webs. Coastal octopods and cuttlefishes store considerably high levels of DA (amnesic shellfish toxin in several tissues, but mainly in the digestive gland (DG—the primary site of digestive absorption and intracellular digestion. Studies on the sub-cellular partitioning of DA in the soluble and insoluble fractions showed that nearly all DA (92.6% is found in the cytosol. This favors the trophic transfer of the toxins since cytosolic substances can be absorbed by predators with greater efficiency. The available information on the accumulation and tissue distribution of DA in squids (e.g., in stranded Humboldt squids, Dosidicus gigas is scarcer than in other cephalopod groups. Regarding paralytic shellfish toxins (PSTs, these organisms accumulate them at the greatest extent in DG >> kidneys > stomach > branchial hearts > posterior salivary glands > gills. Palytoxins are among the most toxic molecules identified and stranded octopods revealed high contamination levels, with ovatoxin (a palytoxin analogue reaching 971 μg kg−1 and palytoxin reaching 115 μg kg−1 (the regulatory limit for PlTXs is 30 μg kg−1 in shellfish. Although the impacts of HAB-toxins in cephalopod physiology are not as well understood as in fish species, similar effects are expected since they possess a complex nervous system and highly developed brain comparable to that of the vertebrates. Compared to bivalves, cephalopods represent a lower risk of shellfish poisoning in humans, since they are usually consumed eviscerated, with exception of traditional dishes from the

  12. The bloom of the dinoflagellate (Noctiluca miliaris) in the North Eastern Arabian Sea: Ship and Satellite study

    Digital Repository Service at National Institute of Oceanography (India)

    Matondkar, S.G.P.; Basu, S.; Parab, S.G.; Pednekar, S.; Dwivedi, R.M.; Raman, M.; Goes, J.I.; Gomes, H.

    were used to establish the onset and demise of this bloom. Simultaneously samples were taken during cruises and these were analyzed for pigments and other associated biological parameters. The bloom period corresponded with the NE monsoon of the region...

  13. .A method for examining temporal changes in cyanobacterial harmful algal bloom spatial extent using satellite remote sensing

    Science.gov (United States)

    Cyanobacterial harmful algal blooms (CyanoHAB) are thought to be increasing globally over the past few decades, but relatively little quantitative information is available about the spatial extent of blooms. Satellite remote sensing provides a potential technology for identifying...

  14. A method for examining temporal changes in cyanobacterial harmful algal bloom spatial extent using satellite remote sensing (Harmful Algae)

    Science.gov (United States)

    Cyanobacterial harmful algal blooms (CyanoHAB) are thought to be increasing globally over the past few decades, but relatively little quantitative information is available about the spatial extent of blooms. Satellite remote sensing provides a potential technology for identifying...

  15. Critical review of actually available chemical compounds for prevention and management of cyanobacterial blooms

    Czech Academy of Sciences Publication Activity Database

    Jančula, Daniel; Maršálek, Blahoslav

    2011-01-01

    Roč. 85, č. 9 (2011), s. 1415-1422 ISSN 0045-6535 R&D Projects: GA MŠk 1M0571 Institutional research plan: CEZ:AV0Z60050516 Keywords : algicide * bloom management * cyanobacterial blooms Subject RIV: EF - Botanics Impact factor: 3.206, year: 2011

  16. Calibrating the Difficulty of an Assessment Tool: The Blooming of a Statistics Examination

    Science.gov (United States)

    Dunham, Bruce; Yapa, Gaitri; Yu, Eugenia

    2015-01-01

    Bloom's taxonomy is proposed as a tool by which to assess the level of complexity of assessment tasks in statistics. Guidelines are provided for how to locate tasks at each level of the taxonomy, along with descriptions and examples of suggested test questions. Through the "Blooming" of an examination--that is, locating its constituent…

  17. An Evaluative Calculus Project: Applying Bloom's Taxonomy to the Calculus Classroom

    Science.gov (United States)

    Karaali, Gizem

    2011-01-01

    In education theory, Bloom's taxonomy is a well-known paradigm to describe domains of learning and levels of competency. In this article I propose a calculus capstone project that is meant to utilize the sixth and arguably the highest level in the cognitive domain, according to Bloom et al.: evaluation. Although one may assume that mathematics is…

  18. Unpacking the Revised Bloom's Taxonomy: Developing Case-Based Learning Activities

    Science.gov (United States)

    Nkhoma, Mathews Zanda; Lam, Tri Khai; Sriratanaviriyakul, Narumon; Richardson, Joan; Kam, Booi; Lau, Kwok Hung

    2017-01-01

    Purpose: The purpose of this paper is to propose the use of case studies in teaching an undergraduate course of Internet for Business in class, based on the revised Bloom's taxonomy. The study provides the empirical evidence about the effect of case-based teaching method integrated the revised Bloom's taxonomy on students' incremental learning,…

  19. Climbing Bloom's Taxonomy Pyramid: Lessons from a Graduate Histology Course

    Science.gov (United States)

    Zaidi, Nikki B.; Hwang, Charles; Scott, Sara; Stallard, Stefanie; Purkiss, Joel; Hortsch, Michael

    2017-01-01

    Bloom's taxonomy was adopted to create a subject-specific scoring tool for histology multiple-choice questions (MCQs). This Bloom's Taxonomy Histology Tool (BTHT) was used to analyze teacher- and student-generated quiz and examination questions from a graduate level histology course. Multiple-choice questions using histological images were…

  20. Algal bloom-associated disease outbreaks among users of freshwater lakes-United States, 2009 - 2010

    Science.gov (United States)

    ‘Algal blooms’ are local abundances of phytoplankton – microscopic photosynthesizing aquatic organisms found in surface waters worldwide; blooms are variable temporally and spatially and frequently produce a visible algal scum on the water. Harmful algal blooms (HABs) are abundan...

  1. Impact of water level fluctuations on cyanobacterial blooms: Options for management

    NARCIS (Netherlands)

    Bakker, E.S.; Hilt, Sabine

    2016-01-01

    Climate change can promote harmful cyanobacteria blooms in eutrophic waters through increased droughts or flooding. In this paper, we explore how water-level fluctuations affect the occurrence of cyanobacterial blooms, and based on the observations from case studies, we discuss the options and

  2. Self-Awareness and Personal Growth: Theory and Application of Bloom's Taxonomy

    Science.gov (United States)

    Ugur, Hasan; Constantinescu, Petru-Madalin; Stevens, Michael J.

    2015-01-01

    Problem Statement: In this article, we summarize a group-based, self-development curriculum based on humanistic principles, framed by contemporary self-determination theory (SDT), and designed in accordance with Bloom's Taxonomy. The processes of awareness and integration are common to SDT and Bloom's Taxonomy, and to our knowledge, have not been…

  3. Importance of deep mixing for initiating the North Atlantic spring bloom

    DEFF Research Database (Denmark)

    Riisgaard, Karen; Paulsen, Maria Lund; Thingstad, T. Frede

    The phytoplankton spring bloom is one of the most important recurrent events in the sup-polar part of the Atlantic Ocean. The classical idea is that the bloom is controlled by nutrients and light, but recent observations challenge this hypothesis. During repeated visits to stations in the deep...

  4. HIGH BREVETOXIN CONCENTRATIONS IN GYMNODINIUM BREVE BLOOMS ALONG THE NORTHWEST FLORIDA COAST DURING 1999.

    Science.gov (United States)

    Blooms of the dinoflagellate Gymnodinium breve (i.e. red tides) produce brevetoxins (PbTx) that negatively impact the Gulf of Mexico ecosystem, human health, and local economics. Characterizing and predicting bloom events and their impacts requires knowledge of G. breve abundance...

  5. Inheritance of Perpetual Blooming in Rosa chinensis ‘Old Blush’

    Directory of Open Access Journals (Sweden)

    Li Shubin

    2015-09-01

    Full Text Available Perpetual blooming is one of the most important biological and economical traits in modern rose, while the genetic basis underlining the control of this trait is poorly investigated. With an aim in dissecting the genetic determinism of perpetual blooming, we developed six rose populations (OB, W, F1, F2, BC1OB and BC1W derived from a WOB population [interspecific diploid hybridization between Rosa chinensis ‘Old Blush’ (OB and R. wichuriana ‘Basye’s Thornless’ (W]. Perpetual blooming is absent both in a F1 population with 296 individuals and a BC1W population (W as the backcross parent with 150 individuals. However, the perpetual blooming trait showed a typical 3:1 segregation in a backcross population BC1OB with OB as the backcross parent. In this population with 300 individuals, 83 plants had the perpetual blooming phenotype while the other 217 featured non-perpetual blooming, indicating that the perpetual blooming trait is very likely controlled by two recessive genes in R. chinensis (rpb1 and rpb2. These genetic data suggest that the inheritance of rose perpetual blooming may be controlled by a complex mechanism.

  6. The Internationalization of Bloom's Learning for Mastery: A 25-Year Retrospective-Prospective View.

    Science.gov (United States)

    Hymel, Glenn M.; Dyck, Walter E.

    Twenty-five years have elapsed since the publication of Benjamin S. Bloom's article titled "Learning for Mastery." With approximately 2,000 master learning/testing citations in the ERIC data base alone, Bloom's 1968 piece is indeed one of the most generative works to appear in the educational psychology literature in decades. At this…

  7. Unusual blooms of green Noctiluca miliaris (Dinophyceae) in the Arabian Sea during the winter monsoon

    Digital Repository Service at National Institute of Oceanography (India)

    Gomes, H.R.; Matondkar, S.G.P.; Parab, S.G.; Goes, J.I.; Pednekar, S.; Al-Azri, A.R.N.; Thoppil, P.G.

    blooms using phytoplankton taxonomic and pigment data from cruises undertaken in 2003-2004 and 2007 as well as ocean color satellite data. Our findings indicate that N. miliaris blooms are becoming an annual and widespread feature in the Arabian Sea. Aqua...

  8. Biomanipulation with quagga mussels (Dreissena rostriformis bugensis) to control harmful algal blooms in eutrophic urban ponds

    NARCIS (Netherlands)

    Waajen, Guido W.A.M.; Bruggen, Van Niek C.B.; Pires, Miguel Dionisio L.; Lengkeek, Wouter; Lurling, Miguel

    2016-01-01

    Many urban ponds in The Netherlands and other countries suffer from eutrophication, resulting in harmful algal blooms which are often dominated by cyanobacteria. A sufficient reduction of nutrients, as prerequisite to mitigate cyanobacterial blooms in urban ponds, is not always feasible. Water

  9. Biomanipulation with quagga mussels (Dreissena rostriformis bugensis) to control harmful algal blooms in eutrophic urban ponds

    NARCIS (Netherlands)

    Waajen, Guido W. A. M.; Van Bruggen, Niek C. B.; Pires, L. Miguel Dionisio; Lengkeek, Wouter; Lurling, Miquel

    Many urban ponds in The Netherlands and other countries suffer from eutrophication, resulting in harmful algal blooms which are often dominated by cyanobacteria. A sufficient reduction of nutrients, as prerequisite to mitigate cyanobacterial blooms in urban ponds, is not always feasible. Water

  10. The costs of respiratory illnesses arising from Florida gulf coast Karenia brevis blooms.

    Science.gov (United States)

    Hoagland, Porter; Jin, Di; Polansky, Lara Y; Kirkpatrick, Barbara; Kirkpatrick, Gary; Fleming, Lora E; Reich, Andrew; Watkins, Sharon M; Ullmann, Steven G; Backer, Lorraine C

    2009-08-01

    Algal blooms of Karenia brevis, a harmful marine algae, occur almost annually off the west coast of Florida. At high concentrations, K. brevis blooms can cause harm through the release of potent toxins, known as brevetoxins, to the atmosphere. Epidemiologic studies suggest that aerosolized brevetoxins are linked to respiratory illnesses in humans. We hypothesized a relationship between K. brevis blooms and respiratory illness visits to hospital emergency departments (EDs) while controlling for environmental factors, disease, and tourism. We sought to use this relationship to estimate the costs of illness associated with aerosolized brevetoxins. We developed a statistical exposure-response model to express hypotheses about the relationship between respiratory illnesses and bloom events. We estimated the model with data on ED visits, K. brevis cell densities, and measures of pollen, pollutants, respiratory disease, and intra-annual population changes. We found that lagged K. brevis cell counts, low air temperatures, influenza outbreaks, high pollen counts, and tourist visits helped explain the number of respiratory-specific ED diagnoses. The capitalized estimated marginal costs of illness for ED respiratory illnesses associated with K. brevis blooms in Sarasota County, Florida, alone ranged from $0.5 to $4 million, depending on bloom severity. Blooms of K. brevis lead to significant economic impacts. The costs of illness of ED visits are a conservative estimate of the total economic impacts. It will become increasingly necessary to understand the scale of the economic losses associated with K. brevis blooms to make rational choices about appropriate mitigation.

  11. Timing of migratory baleen whales at the Azores in relation to the North Atlantic spring bloom

    NARCIS (Netherlands)

    Visser, F.; Hartman, K.L.; Pierce, G.J.; Valavanis, V.D.; Huisman, J.

    2011-01-01

    Each year, a phytoplankton spring bloom starts just north of the North Atlantic Subtropical Gyre, and then expands northwards across the entire North Atlantic. Here, we investigate whether the timing of the spring migration of baleen whales is related to the timing of the phytoplankton spring bloom,

  12. Differential response of coral communities to Caulerpa spp. bloom in the reefs of Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Manikandan, B.; Ravindran, J.

    to the Caulerpa racemosa blooms that occurred in 2013 and 2014. In GoM, the loss of live coral cover was estimated to be 16.5% due to C. taxifolia bloom in 2013. Tissue regeneration by the foliose and branching coral morphotypes aided the recovery of live coral...

  13. Byatt versus Bloom; or Poetic Influence – a Case of Anxiety or Desire?

    DEFF Research Database (Denmark)

    Børch, Marianne

    2013-01-01

    Antonia Byatt's Possession; a Romance (1990) implicitly critiques Harold Bloom's theory of poetic influence as laid out in the influential Anxiety of Influence; her narrative suggests that a better metaphor than Bloom's Oedipal patricide would be that of love, an emotion that opens up for externa...

  14. Phytoplankton ice-edge blooms in the marginal ice zone at Princess Astrid Coast in Antarctica

    Digital Repository Service at National Institute of Oceanography (India)

    Verlecar, X.N.; Dhargalkar, V.K.; Goswami, S.C.; Mhamal, N.P.

    dominated the bloom conditions and nannoplankton (5 to 20 mu m) prevail the non-bloom periods while the picoplankton (less than 5 mu m) constituted a minor fraction during most of the period. Weekly changes in phytoplankton showed inverse relationship...

  15. Nitrogen and phosphorus requirements of an Alexandrium minutum bloom in the Penze' Estuary, France

    Digital Repository Service at National Institute of Oceanography (India)

    Maguer, J.-F.; Wafar, M.V.M.; Madec, C.; Morin, P.; Denn, E.E.

    for sustaining the bloom. Comparison of the measured NO3 uptake rates with advective fluxes indicates that a reduction of NO sub(3) concentrations in river waters to less than 200 Mu mol L sup(-1) would be necessary to contain the bloom in the Penze estuary...

  16. Seawater reverse osmosis desalination and (harmful) algal blooms

    KAUST Repository

    Villacorte, Loreen O.

    2015-03-01

    This article reviews the occurrence of HABs in seawater, their effects on the operation of seawater reverse osmosis (SWRO) plants, the indicators for quantifying/predicting these effects, and the pretreatment strategies for mitigating operational issues during algal blooms. The potential issues in SWRO plants during HABs are particulate/organic fouling of pretreatment systems and biological fouling of RO membranes, mainly due to accumulation of algal organic matter (AOM). The presence of HAB toxins in desalinated water is also a potential concern but only at very low concentrations. Monitoring algal cell density, AOM concentrations and membrane fouling indices is a promising approach to assess the quality of SWRO feedwater and performance of the pretreatment system. When geological condition is favourable, subsurface intake can be a robust pretreatment for SWRO during HABs. Existing SWRO plants with open intake and are fitted with granular media filtration can improve performance in terms of capacity and product water quality, if preceded by dissolved air flotation or sedimentation. However, the application of advanced pretreatment using ultrafiltration membrane with in-line coagulation is often a better option as it is capable of maintaining stable operation and better RO feed water quality during algal bloom periods with significantly lower chemical consumption.

  17. Aerosol Emissions from Great Lakes Harmful Algal Blooms

    Energy Technology Data Exchange (ETDEWEB)

    May, Nathaniel W. [Department; Olson, Nicole E. [Department; Panas, Mark [Department; Axson, Jessica L. [Department; Tirella, Peter S. [Department; Kirpes, Rachel M. [Department; Craig, Rebecca L. [Department; Gunsch, Matthew J. [Department; China, Swarup [William; Laskin, Alexander [William; Ault, Andrew P. [Department; Department; Pratt, Kerri A. [Department; Department

    2017-12-20

    In freshwater lakes, harmful algal blooms (HABs) of Cyanobacteria (blue-green algae) produce toxins that impact human health. However, little is known about the chemical species present in lake spray aerosol (LSA) produced from wave-breaking in freshwater HABs. In this study, a laboratory LSA generator produced aerosols from freshwater samples collected from Lake Michigan and Lake Erie during HAB and non-bloom conditions. Particles were analyzed for size and chemical composition by single particle mass spectrometry, electron microscopy, and fluorescence microscopy, with three distinct types of LSA identified with varying levels of organic carbon and biological material associated with calcium salts. LSA autofluorescence increases with blue-green algae concentration, showing that organic molecules of biological origin are incorporated in LSA from HABs. The number fraction of LSA with biological mass spectral markers also increases with particle diameter (greater than 0.5 μm), showing that HABs have size-dependent impacts on aerosol composition. The highest number fraction of LSA enriched in organic carbon were observed in particles less than 0.5 μm in diameter. Understanding the transfer of organic and biogenic material from freshwater to the atmosphere via LSA particles is crucial for determining health and climate effects due to HABs.

  18. Catchment-fed cyanobacterial blooms in brownified temperate lakes

    Science.gov (United States)

    Senar, O.; Creed, I. F.

    2017-12-01

    One of the most significant impacts of global atmospheric change is the alteration of hydrological regimes and the associated disruption of hydrological connectivity within watersheds. We show how changes in the frequency, magnitude, and duration of hydrological connectivity and disconnectivity is compromising the capacity of forest soils to store organic carbon, and increasing its export to both aquatic and atmospheric systems. Increases in dissolved organic matter (DOM) loads from forested landscapes to aquatic systems and the shift of the DOM pool to a more refractory mixture of organic compounds, a process known as brownification, alters the physical and chemical characteristics of lake environments. Furthermore, by characterizing the stages of brownification (from low to high concentrations of refractory DOM), we show a shift in the limiting factors for phytoplankton growth from macronutrients (nitrogen -N- and phosphorus -P) to micronutrients (iron -Fe) and light availability. This shift is driven by the low concentrations of DOM supplying N and P in early stages of brownification, to the strong Fe-binding capacity of refractory DOM in brownified lakes. As lakes undergo brownification, cyanobacteria adapted to scavenge Fe from DOM-Fe complexes have a competitive advantage leading to the formation of cyanobacterial blooms. Our findings provide evidence that brownification is a driving force leading to cyanobacterial blooms in lakes on forested landscapes, with expected cascading consequences to lake food webs.

  19. Algal Blooms and Cyanotoxins in Jordan Lake, North Carolina

    Directory of Open Access Journals (Sweden)

    Daniel Wiltsie

    2018-02-01

    Full Text Available The eutrophication of waterways has led to a rise in cyanobacterial, harmful algal blooms (CyanoHABs worldwide. The deterioration of water quality due to excess algal biomass in lakes has been well documented (e.g., water clarity, hypoxic conditions, but health risks associated with cyanotoxins remain largely unexplored in the absence of toxin information. This study is the first to document the presence of dissolved microcystin, anatoxin-a, cylindrospermopsin, and β-N-methylamino-l-alanine in Jordan Lake, a major drinking water reservoir in North Carolina. Saxitoxin presence was not confirmed. Multiple toxins were detected at 86% of the tested sites and during 44% of the sampling events between 2014 and 2016. Although concentrations were low, continued exposure of organisms to multiple toxins raises some concerns. A combination of discrete sampling and in-situ tracking (Solid Phase Adsorption Toxin Tracking [SPATT] revealed that microcystin and anatoxin were the most pervasive year-round. Between 2011 and 2016, summer and fall blooms were dominated by the same cyanobacterial genera, all of which are suggested producers of single or multiple cyanotoxins. The study’s findings provide further evidence of the ubiquitous nature of cyanotoxins, and the challenges involved in linking CyanoHAB dynamics to specific environmental forcing factors are discussed.

  20. Lake level fluctuations boost toxic cyanobacterial "oligotrophic blooms".

    Directory of Open Access Journals (Sweden)

    Cristiana Callieri

    Full Text Available Global warming has been shown to strongly influence inland water systems, producing noticeable increases in water temperatures. Rising temperatures, especially when combined with widespread nutrient pollution, directly favour the growth of toxic cyanobacteria. Climate changes have also altered natural water level fluctuations increasing the probability of extreme events as dry periods followed by heavy rains. The massive appearance of Dolichospermum lemmermannii ( = planktonic Anabaena, a toxic species absent from the pelagic zone of the subalpine oligotrophic Lake Maggiore before 2005, could be a consequence of the unusual fluctuations of lake level in recent years. We hypothesized that these fluctuations may favour the cyanobacterium as result of nutrient pulses from the biofilms formed in the littoral zone when the lake level is high. To help verify this, we exposed artificial substrates in the lake, and evaluated their nutrient enrichment and release after desiccation, together with measurements of fluctuations in lake level, precipitation and D. lemmermannii population. The highest percentage of P release and the lowest C:P molar ratio of released nutrients coincided with the summer appearance of the D. lemmermannii bloom. The P pulse indicates that fluctuations in level counteract nutrient limitation in this lake and it is suggested that this may apply more widely to other oligotrophic lakes. In view of the predicted increase in water level fluctuations due to climate change, it is important to try to minimize such fluctuations in order to mitigate the occurrence of cyanobacterial blooms.

  1. Is iron a limiting factor of Nodularia spumigena blooms?

    Directory of Open Access Journals (Sweden)

    Lidia Paczuska

    2003-12-01

    Full Text Available It is well known that a deficiency of iron, a trace element essential to every living organism, limits the growth of algae and cyanobacteria. Nodularia spumigena Mertens is a blue-green algae species inhabiting the Baltic region that often forms toxic blooms.     The aim of the study was to assess the growth of the toxic cyanobacteria with respect to iron bioavailability. The measured growth parameters were the numbers of cells (optical density, chlorophyll a and pheopigment a concentrations. The iron concentrations used ranged from 10-7 to 10-4 mol dm-3. Under iron stress conditions (<5 × 10-7 mol dm-3, growth inhibition, gradual pigment decay and cell mortality were observed. However, enriching the medium with complexing factors like citric acid and EDTA significantly stimulated the growth rate and chlorophyll a production. The citric acid - EDTA - Fe (5 × 10-7 mol dm-3 complex was demonstrably effective in stimulating the rate of cell division. Starting with 10-6 mol dm-3, the higher the iron(III concentration used in the media, the more intensive the growth of the cyanobacteria populations. This was most rapid in the presence of high iron concentrations (10-4 mol dm-3, regardless of the presence of complexing agents.     It appears that the growth of toxic cyanobacteria N. spumigena, and thus also its ability to form blooms, may well depend on iron availability in the environment.

  2. Allelopathic and Bloom-Forming Picocyanobacteria in a Changing World

    Directory of Open Access Journals (Sweden)

    Sylwia Śliwińska-Wilczewska

    2018-01-01

    Full Text Available Picocyanobacteria are extremely important organisms in the world’s oceans and freshwater ecosystems. They play an essential role in primary production and their domination in phytoplankton biomass is common in both oligotrophic and eutrophic waters. Their role is expected to become even more relevant with the effect of climate change. However, this group of photoautotrophic organisms still remains insufficiently recognized. Only a few works have focused in detail on the occurrence of massive blooms of picocyanobacteria, their toxicity and allelopathic activity. Filling the gap in our knowledge about the mechanisms involved in the proliferation of these organisms could provide a better understanding of aquatic environments. In this review, we gathered and described recent information about allelopathic activity of picocyanobacteria and occurrence of their massive blooms in many aquatic ecosystems. We also examined the relationships between climate change and representative picocyanobacterial genera from freshwater, brackish and marine ecosystems. This work emphasizes the importance of studying the smallest picoplanktonic fractions of cyanobacteria.

  3. Bacterial and protist community changes during a phytoplankton bloom

    KAUST Repository

    Pearman, John K.

    2015-10-01

    The present study aims to characterize the change in the composition and structure of the bacterial and microzooplankton planktonic communities in relation to the phytoplankton community composition during a bloom. High-throughput amplicon sequencing of regions of the 16S and 18S rRNA gene was undertaken on samples collected during a 20 day (d) mesocosm experiment incorporating two different nutrient addition treatments [Nitrate and Phosphate (NPc) and Nitrate, Phosphate and Silicate (NPSc)] as well as a control. This approach allowed us to discriminate the changes in species composition across a broad range of phylogenetic groups using a common taxonomic level. Diatoms dominated the bloom in the NPSc treatment while dinoflagellates were the dominant phytoplankton in the control and NPc treatment. Network correlations highlighted significant interactions between OTUs within each treatment including changes in the composition of Paraphysomonas OTUs when the dominant Chaetoceros OTU switched. The microzooplankton community composition responded to changes in the phytoplankton composition while the prokaryotic community responded more to changes in ammonia concentration.

  4. Differentiating intracellular from extracellular alkaline phosphatase activity in soil by sonication.

    Directory of Open Access Journals (Sweden)

    Shuping Qin

    Full Text Available Differentiating intracellular from extracellular enzyme activity is important in soil enzymology, but not easy. Here, we report on an adjusted sonication method for the separation of intracellular from extracellular phosphatase activity in soil. Under optimal sonication conditions [soil:water ratio  =  1/8 (w/v and power density  =  15 watt ml(-1], the activity of alkaline phosphomonoesterase (phosphatase in a Haplic Cambisol soil increased with sonication time in two distinct steps. A first plateau of enzyme activity was reached between 60 and 100 s, and a second higher plateau after 300 s. We also found that sonication for 100 s under optimal conditions activated most (about 80% of the alkaline phosphatase that was added to an autoclaved soil, while total bacteria number was not affected. Sonication for 300 s reduced the total bacteria number by three orders of magnitude but had no further effects on enzyme activity. Our results indicate that the first plateau of alkaline phosphatase activity was derived from extracellular enzymes attached to soil particles, and the second plateau to the combination of extracellular and intracellular enzymes after cell lysis. We conclude that our adjusted sonication method may be an alternative to the currently used physiological and chloroform-fumigation methods for differentiating intracellular from extracellular phosphatase activity in soil. Further testing is needed to find out whether this holds for other soil types.

  5. Evaluation of fatty acids as biomarkers for a natural plankton community. A field study of a spring bloom and a post-bloom period off West Greenland

    DEFF Research Database (Denmark)

    Reuss, N.; Poulsen, Louise K.

    2002-01-01

    bloom and from I to 5 mug 1-1 during the post bloom. Analysis of the fatty acids showed that when the plankton was dominated by diatoms of the genera Thalassiosira and Chaetoceros, the proportions of C16:1(n-7) and C20:5(n-3) were correspondingly high. C18s, and particularly C18:1(n-9), were more...... and total C18 fatty acids (r = 0.739, P

  6. Extensive Chaetoceros curvisetus bloom in relation to water quality in Port Blair Bay, Andaman Islands.

    Science.gov (United States)

    Begum, Mehmuna; Sahu, Biraja Kumar; Das, Apurba Kumar; Vinithkumar, Nambali Valsalan; Kirubagaran, Ramalingam

    2015-05-01

    Blooming of diatom species Chaetoceros curvisetus (Cleve, 1889) was observed in Junglighat Bay and Haddo Harbour of Port Blair Bay of Andaman and Nicobar Islands during June 2010. Physico-chemical parameters, nutrient concentrations and phytoplankton composition data collected from five stations during 2010 were classified as bloom area (BA) and non-bloom area (NBA) and compared. Elevated values of dissolved oxygen were recorded in the BA, and it significantly varied (p NBA. Among the nutrient parameters studied, nitrate concentration indicated significant variation in BA and NBA (p NBA, indicating its utilization. In Junglighat Bay, the C. curvisetus species constituted 93.4 and 69.2% composition of total phytoplankton population during day 1 and day 2, respectively. The bloom forming stations separated out from the non-bloom forming station in non-parametric multidimensional scaling (nMDS) ordinations; cluster analysis powered by SIMPROF test also grouped the stations as BA and NBA.

  7. Free polyamine content during algal bloom succession in the East China Sea in spring 2010

    Science.gov (United States)

    Liu, Yan; Zhao, Weihong; Li, Caiyan; Miao, Hui

    2017-01-01

    We measured the concentrations and distribution of major polyamines (spermine, putrescine and spermidine) in seawater during successive spring algal blooms in an area of frequent harmful blooms in the East China Sea. Spermine, putrescine, and spermidine concentrations were analyzed by high performance liquid chromatography and ranged from 1-64, 7-81, and 0-19 nmol/L. Spermine was present at the highest concentrations, followed by putrescine and spermidine. In late April, when a diatom bloom dominated by Skeletonema costatum dispersed, polyamine concentrations increased, presumably as a result of diatom decomposition. In early May, when a dinoflagellate bloom dominated by Prorocentrum donghaiense occurred, the polyamine concentration decreased from the level seen in late April. The abundant polyamines that decomposed and were released during the diatom bloom in late April may have promoted the growth of P. donghaiense, resulting in its dominance.

  8. Dormant intracellular Salmonella enterica serovar Typhimurium discriminates among Salmonella pathogenicity island 2 effectors to persist inside fibroblasts.

    Science.gov (United States)

    Núñez-Hernández, Cristina; Alonso, Ana; Pucciarelli, M Graciela; Casadesús, Josep; García-del Portillo, Francisco

    2014-01-01

    Salmonella enterica uses effector proteins delivered by type III secretion systems (TTSS) to colonize eukaryotic cells. Recent in vivo studies have shown that intracellular bacteria activate the TTSS encoded by Salmonella pathogenicity island-2 (SPI-2) to restrain growth inside phagocytes. Growth attenuation is also observed in vivo in bacteria colonizing nonphagocytic stromal cells of the intestinal lamina propria and in cultured fibroblasts. SPI-2 is required for survival of nongrowing bacteria persisting inside fibroblasts, but its induction mode and the effectors involved remain unknown. Here, we show that nongrowing dormant intracellular bacteria use the two-component system OmpR-EnvZ to induce SPI-2 expression and the PhoP-PhoQ system to regulate the time at which induction takes place, 2 h postentry. Dormant bacteria were shown to discriminate the usage of SPI-2 effectors. Among the effectors tested, SseF, SseG, and SseJ were required for survival, while others, such as SifA and SifB, were not. SifA and SifB dispensability correlated with the inability of intracellular bacteria to secrete these effectors even when overexpressed. Conversely, SseJ overproduction resulted in augmented secretion and exacerbated bacterial growth. Dormant bacteria produced other effectors, such as PipB and PipB2, that, unlike what was reported for epithelial cells, did not to traffic outside the phagosomal compartment. Therefore, permissiveness for secreting only a subset of SPI-2 effectors may be instrumental for dormancy. We propose that the S. enterica serovar Typhimurium nonproliferative intracellular lifestyle is sustained by selection of SPI-2 effectors that are produced in tightly defined amounts and delivered to phagosome-confined locations.

  9. A method for functional trans-complementation of intracellular Francisella tularensis.

    Directory of Open Access Journals (Sweden)

    Shaun Steele

    Full Text Available Francisella tularensis is a highly infectious bacterial pathogen that invades and replicates within numerous host cell types. After uptake, F. tularensis bacteria escape the phagosome, replicate within the cytosol, and suppress cytokine responses. However, the mechanisms employed by F. tularensis to thrive within host cells are mostly unknown. Potential F. tularensis mutants involved in host-pathogen interactions are typically discovered by negative selection screens for intracellular replication or virulence. Mutants that fulfill these criteria fall into two categories: mutants with intrinsic intracellular growth defects and mutants that fail to modify detrimental host cell processes. It is often difficult and time consuming to discriminate between these two possibilities. We devised a method to functionally trans-complement and thus identify mutants that fail to modify the host response. In this assay, host cells are consistently and reproducibly infected with two different F. tularensis strains by physically tethering the bacteria to antibody-coated beads. To examine the efficacy of this protocol, we tested phagosomal escape, cytokine suppression, and intracellular replication for F. tularensis ΔripA and ΔpdpC. ΔripA has an intracellular growth defect that is likely due to an intrinsic defect and fails to suppress IL-1β secretion. In the co-infection model, ΔripA was unable to replicate in the host cell when wild-type bacteria infected the same cell, but cytokine suppression was rescued. Therefore, ΔripA intracellular growth is due to an intrinsic bacterial defect while cytokine secretion results from a failed host-pathogen interaction. Likewise, ΔpdpC is deficient for phagosomal escape, intracellular survival and suppression of IL-1β secretion. Wild-type bacteria that entered through the same phagosome as ΔpdpC rescued all of these phenotypes, indicating that ΔpdpC failed to properly manipulate the host. In summary, functional

  10. Relationships between alpha diversity of plant species in bloom and climatic variables across an elevation gradient.

    Science.gov (United States)

    Crimmins, Theresa M; Crimmins, Michael A; Bertelsen, David; Balmat, Jeff

    2008-05-01

    This study analyzes a 20-year record of flowering observations collected near Tucson, Arizona, USA. In contrast to traditional phenological records, this dataset is a record of all species observed in bloom collected in five segments of approximately 1 mile (1.61 km) in length across a 4,158-ft (1,200-m) elevation gradient. The data showed differing seasonal and interannual patterns, demonstrating the influence of climatic factors and elevation on flowering. Miles at higher elevations showed bloom peaks in summer, consistent with temperate and montane communities. Conversely, lower miles demonstrated two distinct flowering seasons, typical of the surrounding Sonoran Desert. Interannual fluctuations in total species observed in bloom were not consistent across the 5 miles (c. 8 km), suggesting that these communities respond to different flowering cues. Consistent with documented flowering triggers in semi-arid systems, the alpha diversity of species in bloom at lower elevations in this study was strongly influenced by precipitation. Upper elevation bloom numbers were heavily influenced by temperature, correspondent with bloom triggers in temperate and montane systems. In general, different life forms exhibited similar bloom triggers within the study miles, believed to be a function of shallow soils. Multivariate community analyses showed that anomalous climate conditions yielded unique seasonal bloom compositions. Over the course of the study, average summer temperature showed an upward trend; the number of species in bloom in summer (July-October) in the highest mile (1,940-2,210 m) demonstrated a concurrent increasing trend. Community analysis suggested a gradual shift in the composition of species in bloom in this mile over the study period.

  11. Contributions of meteorology to the phenology of cyanobacterial blooms: implications for future climate change.

    Science.gov (United States)

    Zhang, Min; Duan, Hongtao; Shi, Xiaoli; Yu, Yang; Kong, Fanxiang

    2012-02-01

    Cyanobacterial blooms are often a result of eutrophication. Recently, however, their expansion has also been found to be associated with changes in climate. To elucidate the effects of climatic variables on the expansion of cyanobacterial blooms in Taihu, China, we analyzed the relationships between climatic variables and bloom events which were retrieved by satellite images. We then assessed the contribution of each climate variable to the phenology of blooms using multiple regression models. Our study demonstrates that retrieving ecological information from satellite images is meritorious for large-scale and long-term ecological research in freshwater ecosystems. Our results show that the phenological changes of blooms at an inter-annual scale are strongly linked to climate in Taihu during the past 23 yr. Cyanobacterial blooms occur earlier and last longer with the increase of temperature, sunshine hours, and global radiation and the decrease of wind speed. Furthermore, the duration increases when the daily averages of maximum, mean, and minimum temperature each exceed 20.3 °C, 16.7 °C, and 13.7 °C, respectively. Among these factors, sunshine hours and wind speed are the primary contributors to the onset of the blooms, explaining 84.6% of their variability over the past 23 yr. These factors are also good predictors of the variability in the duration of annual blooms and determined 58.9% of the variability in this parameter. Our results indicate that when nutrients are in sufficiently high quantities to sustain the formation of cyanobacterial blooms, climatic variables become crucial in predicting cyanobacterial bloom events. Climate changes should be considered when we evaluate how much the amount of nutrients should be reduced in Taihu for lake management. Copyright © 2011 Elsevier Ltd. All rights reserved.

  12. Identification of Phytoplankton Blooms under the Index of Inherent Optical Properties (IOP Index in Optically Complex Waters

    Directory of Open Access Journals (Sweden)

    Jesús A. Aguilar-Maldonado

    2018-01-01

    Full Text Available Phytoplankton blooms are sporadic events in time and are isolated in space. This complex phenomenon is produced by a variety of both natural and anthropogenic causes. Early detection of this phenomenon, as well as the classification of a water body under conditions of bloom or non-bloom, remains an unresolved problem. This research proposes the use of Inherent Optical Properties (IOPs in optically complex waters to detect the bloom or non-bloom state of the phytoplankton community. An IOP index is calculated from the absorption coefficients of the colored dissolved organic matter (CDOM, the phytoplankton (phy and the detritus (d, using the wavelength (λ 443 nm. The effectiveness of this index is tested in five bloom events in different places and with different characteristics from Mexican seas: 1. Dzilam (Caribbean Sea, Atlantic Ocean, a diatom bloom (Rhizosolenia hebetata; 2. Holbox (Caribbean Sea, Atlantic Ocean, a mixed bloom of dinoflagellates (Scrippsiella sp. and diatoms (Chaetoceros sp.; 3. Campeche Bay in the Gulf of Mexico (Atlantic Ocean, a bloom of dinoflagellates (Karenia brevis; 4. Upper Gulf of California (UGC (Pacific Ocean, a diatom bloom (Coscinodiscus and Pseudo-nitzschia and 5. Todos Santos Bay, Ensenada (Pacific Ocean, a dinoflagellate bloom (Lingulodinium polyedrum. The diversity of sites show that the IOP index is a suitable method to determine the phytoplankton bloom conditions.

  13. High resistance of some oligotrophic bacteria to ionizing radiation

    International Nuclear Information System (INIS)

    Nikitin, D.I.; Tashtemirova, M.A.; Pitryuk, I.A.; Sorokin, V.V.; Oranskaya, M.S.; Nikitin, L.E.

    1994-01-01

    The resistance of seven cultures of eutrophic and oligotrophic bacteria to gamma radiation (at doses up to 360 Gy) was investigated. The bacteria under study were divided into three groups according to their survival ability after irradiation. Methylobacterium organophilum and open-quotes Pedodermatophilus halotoleransclose quotes (LD 50 = 270 Gy) were highly tolerant. By their tolerance, these organisms approached Deinococcus radiodurans. Aquatic ring-shaped (toroidal) bacteria Flectobacillus major and open-quotes Arcocella aquaticaclose quotes (LD 5 = 173 and 210 Gy, respectively) were moderately tolerant. Eutrophic Pseudomonas fluorescens and Escherichia coli (LD 50 = 43 and 38 Gy, respectively) were the most sensitive. X-ray microanalysis showed that in tolerant bacteria the intracellular content of potassium increased and the content of calcium decreased after irradiation. No changes in the element composition of the eutrophic bacterium E. coli were detected. Possible mechanisms of the resistance of oligotrophic bacteria to gamma radiation are discussed

  14. Overlapping riboflavin supply pathways in bacteria.

    Science.gov (United States)

    García-Angulo, Víctor Antonio

    2017-03-01

    Riboflavin derivatives are essential cofactors for a myriad of flavoproteins. In bacteria, flavins importance extends beyond their role as intracellular protein cofactors, as secreted flavins are a key metabolite in a variety of physiological processes. Bacteria obtain riboflavin through the endogenous riboflavin biosynthetic pathway (RBP) or by the use of importer proteins. Bacteria frequently encode multiple paralogs of the RBP enzymes and as for other micronutrient supply pathways, biosynthesis and uptake functions largely coexist. It is proposed that bacteria shut down biosynthesis and would rather uptake riboflavin when the vitamin is environmentally available. Recently, the overlap of riboflavin provisioning elements has gained attention and the functions of duplicated paralogs of RBP enzymes started to be addressed. Results point towards the existence of a modular structure in the bacterial riboflavin supply pathways. Such structure uses subsets of RBP genes to supply riboflavin for specific functions. Given the importance of riboflavin in intra and extracellular bacterial physiology, this complex array of riboflavin provision pathways may have developed to contend with the various riboflavin requirements. In riboflavin-prototrophic bacteria, riboflavin transporters could represent a module for riboflavin provision for particular, yet unidentified processes, rather than substituting for the RBP as usually assumed.

  15. Manganese (Mn oxidation increases intracellular Mn in Pseudomonas putida GB-1.

    Directory of Open Access Journals (Sweden)

    Andy Banh

    Full Text Available Bacterial manganese (Mn oxidation plays an important role in the global biogeochemical cycling of Mn and other compounds, and the diversity and prevalence of Mn oxidizers have been well established. Despite many hypotheses of why these bacteria may oxidize Mn, the physiological reasons remain elusive. Intracellular Mn levels were determined for Pseudomonas putida GB-1 grown in the presence or absence of Mn by inductively coupled plasma mass spectrometry (ICP-MS. Mn oxidizing wild type P. putida GB-1 had higher intracellular Mn than non Mn oxidizing mutants grown under the same conditions. P. putida GB-1 had a 5 fold increase in intracellular Mn compared to the non Mn oxidizing mutant P. putida GB-1-007 and a 59 fold increase in intracellular Mn compared to P. putida GB-1 ∆2665 ∆2447. The intracellular Mn is primarily associated with the less than 3 kDa fraction, suggesting it is not bound to protein. Protein oxidation levels in Mn oxidizing and non oxidizing cultures were relatively similar, yet Mn oxidation did increase survival of P. putida GB-1 when oxidatively stressed. This study is the first to link Mn oxidation to Mn homeostasis and oxidative stress protection.

  16. The role of TREM-2 in internalization and intracellular survival of Brucella abortus in murine macrophages.

    Science.gov (United States)

    Wei, Pan; Lu, Qiang; Cui, Guimei; Guan, Zhenhong; Yang, Li; Sun, Changjiang; Sun, Wanchun; Peng, Qisheng

    2015-02-15

    Triggering receptor expressed on myeloid cells-2 (TREM-2) is a cell surface receptor primarily expressed on macrophages and dendritic cells. TREM-2 functions as a phagocytic receptor for bacteria as well as an inhibitor of Toll like receptors (TLR) induced inflammatory cytokines. However, the role of TREM-2 in Brucella intracellular growth remains unknown. To investigate whether TREM-2 is involved in Brucella intracellular survival, we chose bone marrow derived macrophages (BMDMs), in which TREM-2 is stably expressed, as cell model. Colony formation Units (CFUs) assay suggests that TREM-2 is involved in the internalization of Brucella abortus (B. abortus) by macrophages, while silencing of TREM-2 decreases intracellular survival of B. abortus. To further study the underlying mechanisms of TREM-2-mediated bacterial intracellular survival, we examined the activation of B. abortus-infected macrophages through determining the kinetics of activation of the three MAPKs, including ERK, JNK and p38, and measuring TNFα production in response to lipopolysaccharide (LPS) of Brucella (BrLPS) or B. abortus stimulation. Our data show that TREM-2 deficiency promotes activation of Brucella-infected macrophages. Moreover, our data also demonstrate that macrophage activation promotes killing of Brucella by enhancing nitric oxygen (NO), but not reactive oxygen species (ROS) production, macrophage apoptosis or cellular death. Taken together, these findings provide a novel interpretation of Brucella intracellular growth through inhibition of NO production produced by TREM-2-mediated activated macrophages. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Intracellular phase for an extracellular bacterial pathogen: MgtC shows the way

    Directory of Open Access Journals (Sweden)

    Audrey Bernut

    2015-08-01

    Full Text Available Pseudomonas aeruginosa is an extracellular pathogen known to impair host phagocytic functions. However, our recent results identify MgtC as a novel actor in P. aeruginosa virulence, which plays a role in an intramacrophage phase of this pathogen. In agreement with its intracellular function, P. aeruginosa mgtC gene expression is strongly induced when the bacteria reside within macrophages. MgtC was previously known as a horizontally-acquired virulence factor important for multiplication inside macrophages in several intracellular bacterial pathogens. MgtC thus provides a singular example of a virulence determinant that subverts macrophages both in intracellular and extracellular pathogens. Moreover, we demonstrate that P. aeru-ginosa MgtC is required for optimal growth in Mg2+ deprived medium, a property shared by MgtC factors from intracellular pathogens and, under Mg2+ limitation, P. aeruginosaMgtC prevents biofilm formation. We propose that MgtC has a similar function in intracellular and extracellular pathogens, which contributes to macrophage resistance and fine-tune adaptation to the host in relation to the different bacterial lifestyles. MgtC thus appears as an attractive target for antivirulence strategies and our work provides a natural peptide as MgtC antagonist, which paves the way for the development of MgtC inhibitors.

  18. Effect of probenecid on phagocytosis and intracellular killing of Staphylococcus aureus and Escherichia coli by human monocytes and granulocytes.

    Science.gov (United States)

    Buisman, H P; Buys, L F; Langermans, J A; van den Broek, P J; van Furth, R

    1991-01-01

    The present study concerns the effects of probenecid on the phagocytosis and intracellular killing of Staphylococcus aureus and Escherichia coli by human monocytes and granulocytes. In both monocytes and granulocytes the inhibitory effect on phagocytosis was very small. Inhibition of intracellular killing of S. aureus by monocytes and granulocytes by probenecid was concentration dependent, being half-maximal at about 2 mM probenecid, and near-maximal at about 5 mM probenecid. The intracellular killing could also be inhibited when probenecid was added when this process was already started. Probenecid also inhibited the intracellular killing of E. coli by granulocytes, but not by monocytes. In the concentration range used, probenecid had no toxic effect on phagocytes or bacteria during the 2 hr of the experiments. PMID:1748482

  19. An overview of cyanobacterial bloom occurrences and research in Africa over the last decade.

    Science.gov (United States)

    Ndlela, L L; Oberholster, P J; Van Wyk, J H; Cheng, P H

    2016-12-01

    Cyanobacterial blooms are a current cause for concern globally, with vital water sources experiencing frequent and increasingly toxic blooms in the past decade. These increases are resultant of both anthropogenic and natural factors, with climate change being the central concern. Of the more affected parts of the world, Africa has been considered particularly vulnerable due to its historical predisposition and lag in social economic development. This review collectively assesses the available information on cyanobacterial blooms in Africa as well as any visible trends associated with reported occurrences over the last decade. Of the 54 countries in Africa, only 21 have notable research information in the area of cyanobacterial blooms within the last decade, although there is substantial reason to attribute these blooms as some of the major water quality threats in Africa collectively. The collected information suggests that civil wars, disease outbreaks and inadequate infrastructure are at the core of Africa's delayed advancement. This is even more so in the area of cyanobacteria related research, with 11 out of 21 countries having recorded toxicity and physicochemical parameters related to cyanobacterial blooms. Compared to the rest of the continent, peripheral countries are at the forefront of research related to cyanobacteria, with countries such as Angola having sufficient rainfall, but poor water quality with limited information on bloom occurrences. An assessment of the reported blooms found nitrogen concentrations to be higher in the water column of more toxic blooms, validating recent global studies and indicating that phosphorous is not the only factor to be monitored in bloom mitigation. Blooms occurred at low TN: TP ratios and at temperatures above 12°C. Nitrogen was linked to toxicity and temperature also had a positive effect on bloom occurrence and toxicity. Microcystis was the most ubiquitous of the cyanobacterial strains reported in Africa and the

  20. Cyanobacterial Toxin Degrading Bacteria: Who Are They?

    Directory of Open Access Journals (Sweden)

    Konstantinos Ar. Kormas

    2013-01-01

    Full Text Available Cyanobacteria are ubiquitous in nature and are both beneficial and detrimental to humans. Benefits include being food supplements and producing bioactive compounds, like antimicrobial and anticancer substances, while their detrimental effects are evident by toxin production, causing major ecological problems at the ecosystem level. To date, there are several ways to degrade or transform these toxins by chemical methods, while the biodegradation of these compounds is understudied. In this paper, we present a meta-analysis of the currently available 16S rRNA and mlrA (microcystinase genes diversity of isolates known to degrade cyanobacterial toxins. The available data revealed that these bacteria belong primarily to the Proteobacteria, with several strains from the sphingomonads, and one from each of the Methylobacillus and Paucibacter genera. Other strains belonged to the genera Arthrobacter, Bacillus, and Lactobacillus. By combining the ecological knowledge on the distribution, abundance, and ecophysiology of the bacteria that cooccur with toxic cyanobacterial blooms and newly developed molecular approaches, it is possible not only to discover more strains with cyanobacterial toxin degradation abilities, but also to reveal the genes associated with the degradation of these toxins.

  1. Bleach vs. Bacteria

    Science.gov (United States)

    ... Articles | Inside Life Science Home Page Bleach vs. Bacteria By Sharon Reynolds Posted April 2, 2014 Your ... hypochlorous acid to help kill invading microbes, including bacteria. Researchers funded by the National Institutes of Health ...

  2. Activation of NADPH oxidase is essential, but not sufficient, in controlling intracellular multiplication of Burkholderia pseudomallei in primary human monocytes.

    Science.gov (United States)

    Wikraiphat, Chanthiwa; Pudla, Matsayapan; Baral, Pankaj; Kitthawee, Sangvorn; Utaisincharoen, Pongsak

    2014-06-01

    Burkholderia pseudomallei is a Gram-negative intracellular bacterium and the causative agent of melioidosis. Innate immune mechanisms against this pathogen, which might contribute to outcomes of melioidosis, are little known. We demonstrated here that B. pseudomallei could activate NADPH oxidase in primary human monocytes as judged by production of reactive oxygen species (ROS) and p40(phox) phosphorylation after infection. However, as similar to other intracellular bacteria, this bacterium was able to resist and multiply inside monocytes despite being able to activate NADPH oxidase. In the presence of NADPH oxidase inhibitor, diphenyleneiodonium or apocynin, intracellular multiplication of B. pseudomallei was significantly increased, suggesting that NADPH oxidase-mediated ROS production is essential in suppressing intracellular multiplication of B. pseudomallei. Additionally, interferon-γ (IFN-γ)-mediated intracellular killing of B. pseudomallei requires NADPH oxidase activity, even though ROS level was not detected at higher levels in IFN-γ-treated infected monocytes. Altogether, these results imply that the activation of NADPH plays an essential role in suppressing intracellular multiplication of B. pseudomallei in human monocytes, although this enzyme is not sufficient to stop intracellular multiplication. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  3. Blooms of bryozoans and epibenthic diatoms in an urbanized sandy Beach (Balneário Camboriú - SC - Brazil: dynamics, possible causes and biomass characterization

    Directory of Open Access Journals (Sweden)

    Leonardo Rubi Rörig

    moderate antimicrobial activity against Klebsiella pneumoniae. The explanation for the occurrence of these blooms are still inconclusive, but there is considerable evidence that it is a synergistic effect between the high concentration of bacteria and organic debris in the water related to local pollution and the elimination of natural competitors by coastal works.

  4. Study of Harmful Algae Blooms Using UAS Imagery

    Science.gov (United States)

    Dumitriu, Ileana; Spacher, Peter; Halfman, John

    2017-04-01

    Harmful Algal Blooms (HABs) occurrence has increased in recent decades. The transient nature of HABs in both space and time result in monitoring challenges, which add to the difficulty in understanding the criteria that trigger HABs. Traditional monitoring programs are expensive and time consuming. The use of UAS (Unmanned Aerial Systems) assures high-resolution space and time monitoring for HABs, and is economical for small bodies of water. By using UAS (Matrice100 and Phantom3) we obtained aerial photographs of eight Finger Lakes which span the oligotrophic to eutrophic spectrum of algal productivity. Water samples were collected and analyzed simultaneously. The Green/Blue (G/B) ratio extracted from the aerial photos was proportional to chlorophyll-a abundance. The algal pigments are also characterized by unique light absorbance and reflectance features, and spectral images obtained from two up-down visible spectrometers revealed a prominent feature 790 nm which correlates to the concentration of algae in the water.

  5. Heterotrophic nanoflagellate grazing facilitates subarctic Atlantic bloom development

    DEFF Research Database (Denmark)

    Paulsen, Maria Lund; Riisgaard, Karen; St. John, Michael

    2017-01-01

    and was substantially higher than the growth of the larger microzooplankton (MZP), i.e. ciliates and dinoflagellates. During the first experiment, small phytoplankton dominated and overall protist grazing (HNF + MZP) was low. In the later experiments, MZP grazing on HNF became evident; however, MZP were not able......-down control of small-sized phytoplankton, thus paving the way for a diatomdominated spring bloom. To assess the trophic role of protist grazers during the winter to spring transition, 3 experiments were performed using size-fractionated surface water from the Iceland Basin (March−April 2012......). These experiments demonstrated heterotrophic nanoflagellates (HNF) grazing of picophytoplankton to be a key pathway, even though these are rarely considered as important phytoplankton grazers in high-latitude systems. The growth rate of HNF was significantly correlated to the biomass of picophytoplankton...

  6. Marine harmful algal blooms, human health and wellbeing

    DEFF Research Database (Denmark)

    Berdalet, Elisa; Fleming, Lora E.; Gowen, Richard

    2016-01-01

    cause harm to humans and other organisms. These harmful algal blooms (HABs) have direct impacts on human health and negative influences on human wellbeing, mainly through their consequences to coastal ecosystem services (fisheries, tourism and recreation) and other marine organisms and environments....... HABs are natural phenomena, but these events can be favoured by anthropogenic pressures in coastal areas. Global warming and associated changes in the oceans could affect HAB occurrences and toxicity as well, although forecasting the possible trends is still speculative and requires intensive...... multidisciplinary research. At the beginning of the 21st century, with expanding human populations, particularly in coastal and developing countries, mitigating HABs impacts on human health and wellbeing is becoming a more pressing public health need. The available tools to address this global challenge include...

  7. Sedimentation of phytoplankton during a diatom bloom : Rates and mechanisms

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Hansen, J.L.S.; Alldredge, A.L.

    1996-01-01

    velocities, settling of cells attached to marine snow aggregates formed from discarded larvacean houses or pteropod feeding webs, and packaging of cells into rapidly falling zooplankton fecal pellets. We quantified the relative significance of these different mechanisms during a diatom bloom in a temperate...... recorded in the water column (by divers) nor in sediment traps. The low coagulation rates were due to a very low 'stickiness' of suspended particles. The dominant diatom, Thalassiosira mendiolana, that accounted for up to 75% of the phytoplankton biomass, was not sticky at al, and did not turn sticky upon...... nutrient depletion in culture experiments. The low particle stickiness recorded may be related to low formation rates by diatoms of transparent exopolymeric particles (TEP), that occurred in low concentrations throughout the study period. Zooplankton grazing rate did not respond to the development...

  8. Factors determining the diurnal dynamics of blooming of chosen plant species

    Directory of Open Access Journals (Sweden)

    Bożena Denisow

    2012-12-01

    Full Text Available The paper attempts to synthesize the determinants which may influence the diurnal rhythm of blooming. Additionally, I tried to explore and bring together topics that concern blooming and have always been considered separately because of their origin in different disciplines. The following species were included: Hydrangea arborescens L. subsp. discolor (Raf., H. paniculata Sieb., Viburnum opulus L., Chaenomeles japonica Lindl., Knautia arvensis L., Adonis vernalis L., Aster saggitifolius Willd., Taraxacum officinale L. Chelidonium majus L. The taxons were observed in Lublin (51008' - 51018' N and 21027' - 21041' E in the years 2001-2007. The blooming of species was determined at least for two vegetation seasons. During observations all flowers developed in one-hour intervals were counted. The diurnal dynamics of blooming differs among species and is modified by different endogenous and exogenous factors. The endogenous determinants of diurnal dynamics of blooming are morphological diversity of flowers (fertility or sterility within species or heterostyly. The different pattern of blooming succour different mechanisms which prevent self-pollination (Chaenomeles japonica Lindl., Knautia arvensis L.. The abiotic factors, such as day length and temperature during the vegetation season, influence the change in the process of diurnal dynamics of blooming (e. g. Taraxacum officinale, Chelidonium majus.

  9. Comparative Metagenomics of Toxic Freshwater Cyanobacteria Bloom Communities on Two Continents

    Energy Technology Data Exchange (ETDEWEB)

    Steffen, Morgan M [ORNL; Li, Zhou [ORNL; Effler, Chad [Department of Microbiology, University of Tennessee; Hauser, Loren John [ORNL; Boyer, Gergory [College of Environmental Science and Forestry, State University of New York, Syracuse; Wilhelm, Steven W [ORNL

    2012-01-01

    Toxic cyanobacterial blooms have persisted in freshwater systems around the world for centuries and appear to be globally increasing in frequency and severity. Toxins produced by bloom-associated cyanobacteria can have drastic impacts on the ecosystem and surrounding communities, and bloom biomass can disrupt aquatic food webs and act as a driver for hypoxia. Little is currently known regarding the genomic content of the Microcystis strains that form blooms or the companion heterotrophic community associated with bloom events. To address these issues, we examined the bloomassociated microbial communities in single samples from Lake Erie (North America), Lake Tai (Taihu, China), and Grand Lakes St. Marys (OH, USA) using comparative metagenomics. Together the Cyanobacteria and Proteobacteria comprised .90% of each bloom bacterial community sample, although the dominant phylum varied between systems. Relative to the existing Microcystis aeruginosa NIES 843 genome, sequences from Lake Erie and Taihu revealed a number of metagenomic islands that were absent in the environmental samples. Moreover, despite variation in the phylogenetic assignments of bloomassociated organisms, the functional potential of bloom members remained relatively constant between systems. This pattern was particularly noticeable in the genomic contribution of nitrogen assimilation genes. In Taihu, the genetic elements associated with the assimilation and metabolism of nitrogen were predominantly associated with Proteobacteria, while these functions in the North American lakes were primarily contributed to by the Cyanobacteria. Our observations build on an emerging body of metagenomic surveys describing the functional potential of microbial communities as more highly conserved than that of their phylogenetic makeup within natural systems.

  10. Intracellular transport: from physics to ... biology.

    Science.gov (United States)

    Roux, Aurélien; Cuvelier, Damien; Bassereau, Patricia; Goud, Bruno

    2008-03-01

    Considerable effort over the past three decades has allowed the identification of the protein families that control the cellular machinery responsible for intracellular transport within eukaryotic cells. These proteins are estimated to represent about 10-20% of the human "proteome." The complexity of intracellular transport makes useful the development of model membranes. We describe here experimental systems based on lipid giant unilamellar vesicles (GUVs), which are attached to kinesin molecules. These systems give rise to thin membrane tubes and to complex tubular networks when incubated in vitro with microtubules and ATP. This type of assay, which mimics key events occurring during intracellular transport, allows physicists and biologists to understand how the unique mechanical properties of lipid membranes could be involved in the budding process, the sorting of cargo proteins and lipids, and the separation of the buds from a donor membrane.

  11. Micro- and nanotechnologies for intracellular delivery.

    Science.gov (United States)

    Yan, Li; Zhang, Jinfeng; Lee, Chun-Sing; Chen, Xianfeng

    2014-11-01

    The majority of drugs and biomolecules need to be delivered into cells to be effective. However, the cell membranes, a biological barrier, strictly resist drugs or biomolecules entering cells, resulting in significantly reduced intracellular delivery efficiency. To overcome this barrier, a variety of intracellular delivery approaches including chemical and physical ways have been developed in recent years. In this review, the focus is on summarizing the nanomaterial routes involved in making use of a collection of receptors for the targeted delivery of drugs and biomolecules and the physical ways of applying micro- and nanotechnologies for high-throughput intracellular delivery. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Fluorescent nanothermometers for intracellular thermal sensing.

    Science.gov (United States)

    Jaque, Daniel; Rosal, Blanca Del; Rodríguez, Emma Martín; Maestro, Laura Martínez; Haro-González, Patricia; Solé, José García

    2014-05-01

    The importance of high-resolution intracellular thermal sensing and imaging in the field of modern biomedicine has boosted the development of novel nanosized fluorescent systems (fluorescent nanothermometers) as the next generation of probes for intracellular thermal sensing and imaging. This thermal mapping requires fluorescent nanothermometers with good biocompatibility and high thermal sensitivity in order to obtain submicrometric and subdegree spatial and thermal resolutions, respectively. This review describes the different nanosized systems used up to now for intracellular thermal sensing and imaging. We also include the later advances in molecular systems based on fluorescent proteins for thermal mapping. A critical overview of the state of the art and the future perspective is also included.

  13. Red to red - the marine bacterium Hahella chejuensis and its product prodigiosin for mitigation of harmful algal blooms.

    Science.gov (United States)

    Kim, Dockyu; Kim, Jihyun F; Yim, Joung Han; Kwon, Soon-Kyeong; Lee, Choong Hwan; Lee, Hong Kum

    2008-10-01

    Harmful algal blooms (HABs), commonly called red tides, are caused by some toxic phytoplanktons, and have made massive economic losses as well as marine environmental disturbances. As an effective and environment-friendly strategy to control HAB outbreaks, biological methods using marine bacteria capable of killing the harmful algae or algicidal extracellular compounds from them have been given attention. A new member of the gamma-Proteobacteria, Hahella chejuensis KCTC 2396, was originally isolated from the Korean seashore for its ability to secrete industrially useful polysaccharides, and was characterized to produce a red pigment. This pigment later was identified as an alkaloid compound, prodigiosin. During the past several decades, prodigiosin has been extensively studied for its medical potential as immunosuppressants and antitumor agents, owing to its antibiotic and cytotoxic activities. The lytic activity of this marvelous molecule against Cochlodinium polykrikoides cells at very low concentrations (1 ppb) was serendipitously detected, making H. chejuensis a strong candidate among the biological agents for HAB control. This review provides a brief overview of algicidal marine bacteria and their products, and describes in detail the algicidal characteristics, biosynthetic process, and genetic regulation of prodigiosin as a model among the compounds active against red-tide organisms from the biochemical and genetic viewpoints.

  14. Importance of a winter dinoflagellate-microflagellate bloom in the Patuxent River estuary

    Science.gov (United States)

    Sellner, K. G.; Lacouture, R. V.; Cibik, S. J.; Brindley, A.; Brownlee, S. G.

    1991-01-01

    A dense bloom of Katodinium rotundatum was observed in the Patuxent River estuary from December to February 1989. The dinoflagellate dominated phytoplankton densities reaching 10 8 cells l -1 and contributed up to 1900 μgC l -1 in near-surface depths. The bloom maintained a distinct patch extending over 10-25 km of the estuary or approximately one-third to one-half of the total estuary (salinities from 5-13 ppt) and was restricted to regions immediately upriver of the transition between the shallow upriver (3-4 m) and deeper lower estuary (10 m). Daily measurements collected in the primary bloom area at the same time each day in the study area indicated 80- and 120-fold variations in chlorophyll and cell densities from day to day. Densities of potential grazers in the region were high with rotifers, primarily Synchaeta baltica, reaching densities of 1000 l -1 in early winter, and the copepod Eurytemora affinis reaching levels exceeding 1·15 × 10 5 m -3 in February. Estimates of grazing pressure by these planktonic herbivores indicated substantial grazing losses for the bloom, with up to 67% of bloom biomass consumed day -1 in February. Nutrient concentrations and ratios of N/P during the bloom suggested potentially N-limited conditions; bloom demise was coincident with a shift to high N/P ratios and high river flows. These data as well as other historical data suggest that dinoflagellate blooms in the lower Patuxent River estuary could be the primary source of carbon to the system during the winter and supply a large reservoir of labile organic matter to planktonic secondary producers prior to annual spring diatom blooms in the region.

  15. Comparative Metagenomics of Toxic Freshwater Cyanobacteria Bloom Communities on Two Continents

    Science.gov (United States)

    Steffen, Morgan M.; Li, Zhou; Effler, T. Chad; Hauser, Loren J.; Boyer, Gregory L.; Wilhelm, Steven W.

    2012-01-01

    Toxic cyanobacterial blooms have persisted in freshwater systems around the world for centuries and appear to be globally increasing in frequency and severity. Toxins produced by bloom-associated cyanobacteria can have drastic impacts on the ecosystem and surrounding communities, and bloom biomass can disrupt aquatic food webs and act as a driver for hypoxia. Little is currently known regarding the genomic content of the Microcystis strains that form blooms or the companion heterotrophic community associated with bloom events. To address these issues, we examined the bloom-associated microbial communities in single samples from Lake Erie (North America), Lake Tai (Taihu, China), and Grand Lakes St. Marys (OH, USA) using comparative metagenomics. Together the Cyanobacteria and Proteobacteria comprised >90% of each bloom bacterial community sample, although the dominant phylum varied between systems. Relative to the existing Microcystis aeruginosa NIES 843 genome, sequences from Lake Erie and Taihu revealed a number of metagenomic islands that were absent in the environmental samples. Moreover, despite variation in the phylogenetic assignments of bloom-associated organisms, the functional potential of bloom members remained relatively constant between systems. This pattern was particularly noticeable in the genomic contribution of nitrogen assimilation genes. In Taihu, the genetic elements associated with the assimilation and metabolism of nitrogen were predominantly associated with Proteobacteria, while these functions in the North American lakes were primarily contributed to by the Cyanobacteria. Our observations build on an emerging body of metagenomic surveys describing the functional potential of microbial communities as more highly conserved than that of their phylogenetic makeup within natural systems. PMID:22952848

  16. Rising CO2 Levels Will Intensify Phytoplankton Blooms in Eutrophic and Hypertrophic Lakes

    Science.gov (United States)

    Verspagen, Jolanda M. H.; Van de Waal, Dedmer B.; Finke, Jan F.; Visser, Petra M.; Van Donk, Ellen; Huisman, Jef

    2014-01-01

    Harmful algal blooms threaten the water quality of many eutrophic and hypertrophic lakes and cause severe ecological and economic damage worldwide. Dense blooms often deplete the dissolved CO2 concentration and raise pH. Yet, quantitative prediction of the feedbacks between phytoplankton growth, CO2 drawdown and the inorganic carbon chemistry of aquatic ecosystems has received surprisingly little attention. Here, we develop a mathematical model to predict dynamic changes in dissolved inorganic carbon (DIC), pH and alkalinity during phytoplankton bloom development. We tested the model in chemostat experiments with the freshwater cyanobacterium Microcystis aeruginosa at different CO2 levels. The experiments showed that dense blooms sequestered large amounts of atmospheric CO2, not only by their own biomass production but also by inducing a high pH and alkalinity that enhanced the capacity for DIC storage in the system. We used the model to explore how phytoplankton blooms of eutrophic waters will respond to rising CO2 levels. The model predicts that (1) dense phytoplankton blooms in low- and moderately alkaline waters can deplete the dissolved CO2 concentration to limiting levels and raise the pH over a relatively wide range of atmospheric CO2 conditions, (2) rising atmospheric CO2 levels will enhance phytoplankton blooms in low- and moderately alkaline waters with high nutrient loads, and (3) above some threshold, rising atmospheric CO2 will alleviate phytoplankton blooms from carbon limitation, resulting in less intense CO2 depletion and a lesser increase in pH. Sensitivity analysis indicated that the model predictions were qualitatively robust. Quantitatively, the predictions were sensitive to variation in lake depth, DIC input and CO2 gas transfer across the air-water interface, but relatively robust to variation in the carbon uptake mechanisms of phytoplankton. In total, these findings warn that rising CO2 levels may result in a marked intensification of

  17. Innate host defense against intracellular pathogens

    NARCIS (Netherlands)

    Vaart, Michiel van der

    2013-01-01

    This thesis focuses on the recognition of pathogenic bacteria and the defense mechanisms that are activated during the innate immune response to infection. Detection of pathogens, such as bacteria, viruses, and parasites, depends on receptors that bind to evolutionary conserved structures on their

  18. Dynamics of microcystin-degrading bacteria in mucilage of Microcystis.

    Science.gov (United States)

    Maruyama, T; Kato, K; Yokoyama, A; Tanaka, T; Hiraishi, A; Park, H D

    2003-08-01

    To reveal the process of degradation of hepatotoxic microcystin produced in Microcystis cells during the Microcystis bloom period, we used fluorescence in situ hybridization (FISH) to analyze the population dynamics of microcystin-degrading bacteria in Microcystis mucilage. We designed and applied an oligonucleotide probe targeted to the 16S rRNA sequence of strain Y2 of a microcystin-degrading bacterium (MCD-bacterium), which was isolated from Lake Suwa, Japan. In both the 1998 and 1999 tests, FISH clearly showed that MCD-bacteria existed in the mucilage and that, when a high concentration of cell-bound microcystin was detected, MCD-bacteria exceeded 10% of the sum of bacteria hybridized with group-specific probes. The concentration of MCD-bacteria was highest in summer 1998, when a toxic species, M. viridis, was dominant. There was a high correlation between the number of MCD-bacteria in the mucilage and the concentration of cell-bound microcystin in the lake. Our results suggest that MCD-bacteria responded to changes in the concentration of microcystin and degraded the microcystin when it was released from Microcystis cells. We also analyzed changes in the bacterial community structure associated with the Microcystis colonies by using domain- and group-specific oligonucleotide probes. Changes in the concentrations of the Cytophaga/Flavobacterium group and delta-Proteobacteria, which can degrade macromolecules derived from Microcystis cells, were synchronized with changes in the concentration of Microcystis. The results not only suggest the significant role of MCD-bacteria in detoxification, but also demonstrate a possible sequence of degradation from Microcystis cells to microcystin maintained in the cell, which is then carried out by bacterial consortia in the mucilage.

  19. Role of intracellular infections in premature childbirth.

    Science.gov (United States)

    Zurabishvili, S; Mamamtavrishvili, I; Apridonidze, K; Shanidze, L

    2005-09-01

    Vaginal Smear taken by sterile Folkman spoon from 15 women with premature birth was studied. The study was performed by the direct immune fluorescence method with the luminescence microscope. We aimed to study the effect of intracellular infections: ureaplasma urealitikum, mycoplasma hominis, Chlamydia trachomatis, herpes simplex virus of I and II type and cytomegalovirus. Intracellular infections were detected in at about 82% of cases, which included mono infections with cytomegalovirus and in 9 cases in the form of bi-component associations. The obtained results may be interesting from the etiologic point of view of premature births in Georgian population.

  20. Economic Cost of an Algae Bloom Cleanup in China's 2008 Olympic Sailing Venue

    Science.gov (United States)

    Wang, X. H.; Li, L.; Bao, X.; Zhao, L. D.

    2009-07-01

    In the summer of 2008, an algae bloom struck the coast of Qingdao, China, where the 2008 Olympic sailing events were to be held. The bloom was caused by the drift and proliferation of the green algae Enteromorpha (see http://precedings.nature.com/documents/2352/version/1). It lasted for more than 1 month and covered nearly the entire sailing venue. The Enteromorpha bloom was so intense that national and local governments invested a tremendous amount of labor and resources in a cleanup effort in order to achieve Olympic Games standards [Hu and He, 2008].

  1. An overview of cyanobacterial blooms occurrences and research in Africa over the last decade

    CSIR Research Space (South Africa)

    Ndlela, Luyanda L

    2016-12-01

    Full Text Available as the 349 dominant species (Boelee et al., 2009). A majority of the reports related to cyanobacteria are 350 not accessible in English however according to Boelee et al. (2009), a study assessing 23 351 lakes and reservoirs by Cecchi et al (2009), found... water source in the area with 404 cyanobacterial blooms. This lake is the largest reservoir supplying freshwater to the capital 405 city of the country. Although reports are not extensive on blooms in the past ten years, toxic 406 blooms have been...

  2. Importance of deep mixing for initiating the North Atlantic spring bloom

    DEFF Research Database (Denmark)

    Riisgaard, Karen; Paulsen, Maria Lund; Thingstad, T. Frede

    Icelandic and the Norwegian Basins and the shallow Shetland Shelf (26 March to 1 May 2012), we investigated the succession and growth dynamics of microscopic grazers prior to the bloom. We demonstrate that deep mixing of the water column play an important role for predator-prey interactions......The phytoplankton spring bloom is one of the most important recurrent events in the sup-polar part of the Atlantic Ocean. The classical idea is that the bloom is controlled by nutrients and light, but recent observations challenge this hypothesis. During repeated visits to stations in the deep...

  3. LANDSAT-derived 28-year history of phytoplankton blooms in Western Lake Erie shows changes in peak bloom timing and challenges due to phytoplankton species variability

    Science.gov (United States)

    Ho, J. C.; Michalak, A. M.; Stumpf, R. P.

    2016-02-01

    Information on historical phytoplankton blooms can yield insight that can be used to tackle present-day challenges in inland waters. Thus far, attempts to use historical information to understand long-term changes relevant for present-day management have been stymied by a limited historical record in many freshwater systems. For Lake Erie, we augment the existing record based on MERIS imagery that begins in 2002 by gleaning information on the spatial extent and timing of blooms for 1984-2001 from LANDSAT 5 imagery. Despite limitations stemming from LANDSAT's long revisit period and regular cloudiness obscuring scenes, we demonstrate that remotely-sensed historical data add relevant context for addressing current blooms by documenting the presence, magnitude, and timing of past blooms. Comparing the remotely-sensed history to the sparse in situ data taken during this period, we find that new information can be gleaned about historical bloom presence, magnitude, and seasonality despite LANDSAT's limitations. We also find that the remotely-sensed record shows systematic differences in the remotely sensed signal as a function of the colony size of the dominant phytoplankton species present, providing a note of caution for using remote sensing to monitor water quality in systems with multiple phytoplankton regime shifts.

  4. A Sra. Tomasetti, Bloom e um projeto de ensino pioneiro Mrs. Tomasetti, Bloom and and early teaching project

    Directory of Open Access Journals (Sweden)

    Everardo Duarte Nunes

    2003-01-01

    Full Text Available O artigo desenvolve uma análise do livro de Samuel W. Bloom, The doctor and his patient: a sociological interpretation, no qual o autor propõe uma forma de abordar os principais conceitos sociológicos para o ensino de estudantes de medicina. O foco central é o relacionamento médico-paciente, a partir do relato do caso de uma paciente e das formas adotadas pelos médicos e outros profissionais na tentativa de cuidar de uma paciente crônica. O principal conceito que embasa a análise é o de sistema social, ao qual se juntam os de papel, normas, instituições. Além de apresentar as grandes linhas dos diversos capítulos desse livro, marco da sociologia médica dos anos 60, o artigo apresenta informações bio-bibliográficas do autor. No final, são feitos comentários, mostrando, de forma geral, que a busca de uma forma de ensino das ciências sociais (em particular, da sociologia, para estudantes de medicina continua a ser um desafio para os educadores.This article presents an analysis of Samuel W. Bloom's book, The doctor and his patient: a sociological interpretation, in which the author offers a way to approach the principal sociological concepts to medical students. The focal point is the doctor-patient relationship starting from the case of chronic woman patient and the patterns adopted by physicians and other professionals to attend the patient. The main concepts used to understand the doctor-patient relationship process are social system, role, norms and institutions. The paper presents the different chapters of this landmark book in medical sociology published in 1963 and bio-bibliographical author's information. The conclusions retake some problems about the teaching of sociology to medical students.

  5. Remote Sensing Marine Ecology: Wind-driven algal blooms in the open oceans and their ecological impacts

    Science.gov (United States)

    Tang, DanLing

    2016-07-01

    Algal bloom not only can increase the primary production but also could result in negative ecological consequence, e.g., Harmful Algal Blooms (HABs). According to the classic theory for the formation of algal blooms "critical depth" and "eutrophication", oligotrophic sea area is usually difficult to form a large area of algal blooms, and actually the traditional observation is only sporadic capture to the existence of algal blooms. Taking full advantage of multiple data of satellite remote sensing, this study: 1), introduces "Wind-driven algal blooms in open oceans: observation and mechanisms" It explained except classic coastal Ekman transport, the wind through a variety of mechanisms affecting the formation of algal blooms. Proposed a conceptual model of "Strong wind -upwelling-nutrient-phytoplankton blooms" in Western South China Sea (SCS) to assess role of wind-induced advection transport in phytoplankton bloom formation. It illustrates the nutrient resources that support long-term offshore phytoplankton blooms in the western SCS; 2), Proposal of the theory that "typhoons cause vertical mixing, induce phytoplankton blooms", and quantify their important contribution to marine primary production; Proposal a new ecological index for typhoon. Proposed remote sensing inversion models. 3), Finding of the spatial and temporaldistributions pattern of harmful algal bloom (HAB)and species variations of HAB in the South Yellow Sea and East China Sea, and in the Pearl River estuary, and their oceanic dynamic mechanisms related with monsoon; The project developed new techniques and generated new knowledge, which significantly improved understanding of the formation mechanisms of algal blooms. 1), It proposed "wind-pump" mechanism integrates theoretical system combing "ocean dynamics, development of algal blooms, and impact on primary production", which will benefit fisheries management. 2), A new interdisciplinary subject "Remote Sensing Marine Ecology"(RSME) has been

  6. Suitability of a cytotoxicity assay for detection of potentially harmful compounds produced by freshwater bloom-forming algae.

    Science.gov (United States)

    Sorichetti, Ryan J; McLaughlin, Jace T; Creed, Irena F; Trick, Charles G

    2014-01-01

    Detecting harmful bioactive compounds produced by bloom-forming pelagic algae is important to assess potential risks to public health. We investigated the application of a cell-based bioassay: the rainbow trout gill-w1 cytotoxicity assay (RCA) that detects changes in cell metabolism. The RCA was used to evaluate the cytotoxic effects of (1) six natural freshwater lake samples from cyanobacteria-rich lakes in central Ontario, Canada; (2) analytical standards of toxins and noxious compounds likely to be produced by the algal communities in these lakes; and (3) complex mixtures of compounds produced by cyanobacterial and chrysophyte cultures. RCA provided a measure of lake water toxicity that could not be reproduced using toxin or noxious compound standards. RCA was not sensitive to toxins and only sensitive to noxious compounds at concentrations higher than reported environmental averages (EC 50 ≥10 3 nM). Cultured algae produced bioactive compounds that had recognizable dose dependent and toxic effects as indicated by RCA. Toxicity of these bioactive compounds depended on taxa (cyanobacteria, not chrysophytes), growth stage (stationary phase more toxic than exponential phase), location (intracellular more toxic than extracellular) and iron status (cells in high-iron treatment more toxic than cells in low-iron treatment). The RCA provides a new avenue of exploration and potential for the detection of natural lake algal toxic and noxious compounds. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Hepatitis C virus intracellular host interactions

    NARCIS (Netherlands)

    Liefhebber, Johanna Maaike Pieternella

    2010-01-01

    Hepatitis C virus (HCV) infects about 170 million people worldwide causing a major healthcare problem. The virus lifecycle is greatly dependent on the host-cell for effective replication. In this thesis, the intracellular interactions of the non-structural HCV proteins with the host-cell were

  8. Enhanced production of intracellular dextran dextrinase from ...

    African Journals Online (AJOL)

    Enhanced production of intracellular dextran dextrinase from Gluconobacter oxydans using statistical experimental methods. ... the Plackett-Burman screening. A four-factor five-level central composite design (CCD) was chosen to explain the combined effects of the four medium constituents. The optimum medium consisted ...

  9. Biological synthesis and characterization of intracellular gold ...

    Indian Academy of Sciences (India)

    ... nontoxic, safe, biocompatible and environmentally acceptable. In the present study, Aspergillus fumigatus was used for the intracellular synthesis of gold nanoparticles. Stable nanoparticles were produced when an aqueous solution of chloroauric acid (HAuCl4) was reduced by A. fumigatus biomass as the reducing agent ...

  10. Efficient intracellular delivery of native proteins

    NARCIS (Netherlands)

    D'Astolfo, Diego S; Pagliero, Romina J; Pras, Anita; Karthaus, Wouter R; Clevers, Hans; Prasad, Vikram; Lebbink, Robert Jan; Rehmann, Holger; Geijsen, Niels

    2015-01-01

    Modulation of protein function is used to intervene in cellular processes but is often done indirectly by means of introducing DNA or mRNA encoding the effector protein. Thus far, direct intracellular delivery of proteins has remained challenging. We developed a method termed iTOP, for induced

  11. Temporal protein expression pattern in intracellular signalling ...

    Indian Academy of Sciences (India)

    2015-09-28

    Sep 28, 2015 ... [Ganguli P, Chowdhury S, Bhowmick R and Sarkar RR 2015 Temporal protein expression pattern in intracellular signalling cascade during T-cell activation: A ... cells and tissues by studying different signalling pathways, such as Hedgehog ...... Murray JD 2003 On the mechanochemical theory of biological.

  12. Optimizing Nanoelectrode Arrays for Scalable Intracellular Electrophysiology.

    Science.gov (United States)

    Abbott, Jeffrey; Ye, Tianyang; Ham, Donhee; Park, Hongkun

    2018-03-20

    Electrode technology for electrophysiology has a long history of innovation, with some decisive steps including the development of the voltage-clamp measurement technique by Hodgkin and Huxley in the 1940s and the invention of the patch clamp electrode by Neher and Sakmann in the 1970s. The high-precision intracellular recording enabled by the patch clamp electrode has since been a gold standard in studying the fundamental cellular processes underlying the electrical activities of neurons and other excitable cells. One logical next step would then be to parallelize these intracellular electrodes, since simultaneous intracellular recording from a large number of cells will benefit the study of complex neuronal networks and will increase the throughput of electrophysiological screening from basic neurobiology laboratories to the pharmaceutical industry. Patch clamp electrodes, however, are not built for parallelization; as for now, only ∼10 patch measurements in parallel are possible. It has long been envisioned that nanoscale electrodes may help meet this challenge. First, nanoscale electrodes were shown to enable intracellular access. Second, because their size scale is within the normal reach of the standard top-down fabrication, the nanoelectrodes can be scaled into a large array for parallelization. Third, such a nanoelectrode array can be monolithically integrated with complementary metal-oxide semiconductor (CMOS) electronics to facilitate the large array operation and the recording of the signals from a massive number of cells. These are some of the central ideas that have motivated the research activity into nanoelectrode electrophysiology, and these past years have seen fruitful developments. This Account aims to synthesize these findings so as to provide a useful reference. Summing up from the recent studies, we will first elucidate the morphology and associated electrical properties of the interface between a nanoelectrode and a cellular membrane

  13. Therapeutic Antibodies against Intracellular Tumor Antigens

    Directory of Open Access Journals (Sweden)

    Iva Trenevska

    2017-08-01

    Full Text Available Monoclonal antibodies are among the most clinically effective drugs used to treat cancer. However, their target repertoire is limited as there are relatively few tumor-specific or tumor-associated cell surface or soluble antigens. Intracellular molecules represent nearly half of the human proteome and provide an untapped reservoir of potential therapeutic targets. Antibodies have been developed to target externalized antigens, have also been engineered to enter into cells or may be expressed intracellularly with the aim of binding intracellular antigens. Furthermore, intracellular proteins can be degraded by the proteasome into short, commonly 8–10 amino acid long, peptides that are presented on the cell surface in the context of major histocompatibility complex class I (MHC-I molecules. These tumor-associated peptide–MHC-I complexes can then be targeted by antibodies known as T-cell receptor mimic (TCRm or T-cell receptor (TCR-like antibodies, which recognize epitopes comprising both the peptide and the MHC-I molecule, similar to the recognition of such complexes by the TCR on T cells. Advances in the production of TCRm antibodies have enabled the generation of multiple TCRm antibodies, which have been tested in vitro and in vivo, expanding our understanding of their mechanisms of action and the importance of target epitope selection and expression. This review will summarize multiple approaches to targeting intracellular antigens with therapeutic antibodies, in particular describing the production and characterization of TCRm antibodies, the factors influencing their target identification, their advantages and disadvantages in the context of TCR therapies, and the potential to advance TCRm-based therapies into the clinic.

  14. Study of Under-ice Blooms In the Chukchi Ecosystem (SUBICE) (HLY1401, EM122)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The primary objectives of SUBICE were to determine the spatial distribution of large under-ice phytoplankton blooms on the Chukchi Shelf and the physical mechanisms...

  15. An overview of diversity, occurrence, genetics and toxin production of bloom-forming Dolichospermum (Anabaena) species.

    Science.gov (United States)

    Li, Xiaochuang; Dreher, Theo W; Li, Renhui

    2016-04-01

    The new genus name Dolichospermum, for most of the planktonic former members of the genus Anabaena, is one of the most ubiquitous bloom-forming cyanobacterial genera. Its dominance and persistence have increased in recent years, due to eutrophication from anthropogenic activities and global climate change. Blooms of Dolichospermum species, with their production of secondary metabolites that commonly include toxins, present a worldwide threat to environmental and public health. In this review, recent advances of the genus Dolichospermum are summarized, including taxonomy, genetics, bloom occurrence, and production of toxin and taste-and-odor compounds. The recent and continuing acquisition of genome sequences is ushering in new methods for monitoring and understanding the factors regulating bloom dynamics. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Bloom Filter-Based Secure Data Forwarding in Large-Scale Cyber-Physical Systems

    Directory of Open Access Journals (Sweden)

    Siyu Lin

    2015-01-01

    Full Text Available Cyber-physical systems (CPSs connect with the physical world via communication networks, which significantly increases security risks of CPSs. To secure the sensitive data, secure forwarding is an essential component of CPSs. However, CPSs require high dimensional multiattribute and multilevel security requirements due to the significantly increased system scale and diversity, and hence impose high demand on the secure forwarding information query and storage. To tackle these challenges, we propose a practical secure data forwarding scheme for CPSs. Considering the limited storage capability and computational power of entities, we adopt bloom filter to store the secure forwarding information for each entity, which can achieve well balance between the storage consumption and query delay. Furthermore, a novel link-based bloom filter construction method is designed to reduce false positive rate during bloom filter construction. Finally, the effects of false positive rate on the performance of bloom filter-based secure forwarding with different routing policies are discussed.

  17. Harmful algal blooms discovered during the Mote Monthly transect cruises, 1998 and 1999 (NODC Accession 0000532)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Harmful algal blooms of the toxic dinoflagellate, Karenia brevis, have caused massive fish kills in the Gulf of Mexico since the 1500's, with most occurrences on the...

  18. "Wax bloom" on beeswax cultural heritage objects: exploring the causes of the phenomenon

    Czech Academy of Sciences Publication Activity Database

    Bartl, B.; Kobera, Libor; Drábková, K.; Ďurovič, M.; Brus, Jiří

    2015-01-01

    Roč. 53, č. 7 (2015), s. 509-513 ISSN 0749-1581 Institutional support: RVO:61389013 Keywords : 13-C NMR * wax bloom * efflorescence Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.226, year: 2015

  19. Satellite Evidence that E. huxleyi Phytoplankton Blooms Weaken Marine Carbon Sinks

    Science.gov (United States)

    Kondrik, D. V.; Pozdnyakov, D. V.; Johannessen, O. M.

    2018-01-01

    Phytoplankton blooms of the coccolithophore Emiliania huxleyi are known to produce CO2, causing less uptake of atmospheric CO2 by the ocean, but a global assessment of this phenomenon has so far not been quantified. Therefore, here we quantify the increase in CO2 partial pressure (ΔpCO2) at the ocean surface within E. huxleyi blooms for polar and subpolar seas using an 18 year ocean color time series (1998-2015). When normalized to pCO2 in the absence of bloom, the mean and maximum ΔpCO2 values within the bloom areas varied between 21.0%-43.3% and 31.6%-62.5%, respectively. These results might have appreciable implications for climatology, marine chemistry, and ecology.

  20. Insights on short–term blooms of planktonic ciliates, provided by an easily recognised genus: Cyrtostrombidium

    Czech Academy of Sciences Publication Activity Database

    Bulit, C.; Macek, Miroslav; Montagnes, D. J. S.

    2013-01-01

    Roč. 52, č. 1 (2013), s. 1-12 ISSN 0065-1583 Institutional support: RVO:60077344 Keywords : bloom * conjugation * parasitism * patch * population dynamics * lagoon Subject RIV: EE - Microbiology, Virology Impact factor: 1.179, year: 2013

  1. BIOMARKER LIPIDS IN RED TIDE (GYMNODINIUM BREVE) BLOOMS ALONG THE NORTHWEST FLORIDA COAST

    Science.gov (United States)

    The ability to characterize phytoplankton communities and algal blooms using lipids as biomarkers requires knowledge of their distribution and taxonomic significance. Such an approach would have application, for example, in distinguishing and tracking certain dinoflagellates suc...

  2. Phytoplankton bloom and subpolar gyre induced dynamics in the North Atlantic

    DEFF Research Database (Denmark)

    Ferreira, Ana Sofia; Hátún, H.; Counillon, F.

    represents the integrated oceanic dynamics over the Northern North Atlantic, while the timing of the spring bloom is more governed by direct atmospheric forcing during the pre-bloom weeks. We, therefore, further investigate which published theories (Sverdrup [1953], Siegel et al [2002], Huisman et al [2002...... dynamics and the subpolar gyre is complex, showing no clear spatial pattern. Our hypothesis is therefore partly refuted, probably due to the disparity in the temporal and spatial resolutions of the subpolar gyre index, compared to indices describing spring bloom dynamics. The annually averaged gyre index......], Townsend et al [1994], and Taylor and Ferrari [2011]) for bloom onset are suited for this region. We construct indicator fields and time series which in various combinations provide models consistent with the principle dynamics proposed in these theories. Using a multi-model inference approach, we...

  3. Swarming of pelagic tunicates associated with phytoplankton bloom in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Madhupratap, M.; Devassy, V.P.; Nair, S.R.S.; Rao, T.S.S.

    During the 40th cruise of R V Gaveshani, a large swarm pelagic tunicates associated with a bloom of diatoms and blue green algae was observed off Nagapattinam. The doliolid Dolioletta gegenbauri, Uljanin, the salp Thalia democratica Forskal...

  4. Deep carbon export from a Southern Ocean iron-fertilized diatom bloom

    Digital Repository Service at National Institute of Oceanography (India)

    Smetacek, V.; Klaas, C.; Strass, V.H.; Assmy, P.; Montresor, M.; Cisewski, B.; Savoye, N.; Webb, A.; d’Ovidio, F.; Arrieta, J.M.; Bathmann, U.; Bellerby, R.; Berg, G.M.; Croot, P.; Gonzalez, S.; Henjes, J.; Herndl, G.J.; Hoffmann, L.J.; Leach, H.; Losch, M.; Mills, M.M.; Neill, C.; Peeken, I.; Rottgers, R.; Sachs, O.; Sauter, E.; Schmidt, M.M.; Schwarz, J.; Terbruggen, A.; Wolf-Gladrow, D.

    , mucilaginous aggregates of entangled cells and chains. Taken together, multiple lines of evidence - although each with important uncertainties - lead us to conclude that at least half the bloom biomass sank far below a depth of 1000 metres and that a...

  5. Selective grazing of Temora longicornis in different stages of a Phaeocystis globosa bloom - a mesocosm study

    DEFF Research Database (Denmark)

    Koski, Marja; Dutz, Jörg; Breteler, W.C.M.K.

    2005-01-01

    Selective grazing of a calanoid copepod Temora longicornis was measured during different stages of a Phaeocystis globosa bloom, in order to reveal (1) if T longicornis feeds on single cells and/or colonies of P. globosa in the presence of alternative food sources, (2) if copepod food selection...... of alternative food sources. In contrast, feeding on single cells was never significant, and the total contribution of P globosa to carbon ingestion of T longicornis was minor. T longicornis fed most actively on the decaying colonies, whereas during the peak of the bloom copepods selected against P globosa...... with highest proportional ingestion of heterotrophic organisms, but was not seriously reduced even during the peak of the bloom. We conclude that P globosa blooms should not threaten survival of copepod populations, but the population recruitment may depend on the type (and concentration) of the dominant...

  6. Factors controlling the origin of Cochlodinium polykrikoides blooms along the Goheung coast, South Korea.

    Science.gov (United States)

    Lee, Moon Ock; Kim, Jong Kyu; Kim, Byeong Kuk

    2016-12-15

    We investigated the factors influencing the origin of Cochlodinium polykrikoides blooms along the Goheung coast (GH), and compared them to those along the Geoje (GJ) coast and in the East China Sea (ECS) which were used as reference sites. Stratification did not develop in GH during C. polykrikoides blooms, unlike that in GJ. The surface salinity during summer in ECS was equivalent to that of GH, whereas surface temperature and concentration of nutrients in ECS were markedly higher than those in GH or GJ. Thermohaline (or thermal) fronts appeared between the Korea Southern Coastal Water (KSCW) and the outer seawater during C. polykrikoides blooms. The result of numerical simulation models indicated that freshwater from the Yangtze River clearly affected KSCW. As a result, the origin of C. polykrikoides blooms in GH during summer could be attributed to the inflow of seawater from ECS with high water temperature and abundant nutrients. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. West Coast DA Event data - West Coast Toxic Pseudo-nitzschia bloom

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Beginning in the spring of 2015 the US West Coast began to experience the most wide-spread toxic Pseudo-nitzschia bloom to date, after approximately eight years...

  8. Monitoring of ocean surface algal blooms in coastal and oceanic waters around India.

    Digital Repository Service at National Institute of Oceanography (India)

    Tholkapiyan, M.; Shanmugam, P.; Suresh, T.

    spatial distribution and intensity of these blooms in the northern Arabian Sea in winter are likely caused by enhanced cooling, increased convective mixing, favorable winds, and atmospheric deposition of the mineral aerosols (from surrounding deserts...

  9. Autophagy Evasion and Endoplasmic Reticulum Subversion: The Yin and Yang of Legionella Intracellular Infection.

    Science.gov (United States)

    Sherwood, Racquel Kim; Roy, Craig R

    2016-09-08

    The gram-negative bacterial pathogen Legionella pneumophila creates a novel organelle inside of eukaryotic host cells that supports intracellular replication. The L. pneumophila-containing vacuole evades fusion with lysosomes and interacts intimately with the host endoplasmic reticulum (ER). Although the natural hosts for L. pneumophila are free-living protozoa that reside in freshwater environments, the mechanisms that enable this pathogen to replicate intracellularly also function when mammalian macrophages phagocytose aerosolized bacteria, and infection of humans by L. pneumophila can result in a severe pneumonia called Legionnaires' disease. A bacterial type IVB secretion system called Dot/Icm is essential for intracellular replication of L. pneumophila. The Dot/Icm apparatus delivers over 300 different bacterial proteins into host cells during infection. These bacterial proteins have biochemical activities that target evolutionarily conserved host factors that control membrane transport processes, which results in the formation of the ER-derived vacuole that supports L. pneumophila replication. This review highlights research discoveries that have defined interactions between vacuoles containing L. pneumophila and the host ER. These studies reveal how L. pneumophila creates a vacuole that supports intracellular replication by subverting host proteins that control biogenesis and fusion of early secretory vesicles that exit the ER and host proteins that regulate the shape and dynamics of the ER. In addition to recruiting ER-derived membranes for biogenesis of the vacuole in which L. pneumophila replicates, these studies have revealed that this pathogen has a remarkable ability to interfere with the host's cellular process of autophagy, which is an ancient cell autonomous defense pathway that utilizes ER-derived membranes to target intracellular pathogens for destruction. Thus, this intracellular pathogen has evolved multiple mechanisms to control membrane

  10. Consortial brown tide − picocyanobacteria blooms in Guantánamo Bay, Cuba

    Science.gov (United States)

    Hall, Nathan S; Litaker, R. Wayne; Kenworthy, W. Judson; Vandersea, Mark W.; Sunda, William G.; Reid, James P.; Slone, Daniel H.; Butler, Susan M.

    2018-01-01

    A brown tide bloom of Aureoumbra lagunensis developed in Guantánamo Bay, Cuba during a period of drought in 2013 that followed heavy winds and rainfall from Hurricane Sandy in late October 2012. Based on satellite images and water turbidity measurements, the bloom appeared to initiate in January 2013. The causative species (A. lagunensis) was confirmed by microscopic observation, and pigment and genetic analyses of bloom samples collected on May 28 of that year. During that time, A. lagunensis reached concentrations of 900,000 cells ml−1 (28 ppm by biovolume) in the middle portion of the Bay. Samples could not be collected from the northern (Cuban) half of the Bay because of political considerations. Subsequent sampling of the southern half of the Bay in November 2013, April 2014, and October 2014 showed persistent lower concentrations of A. lagunensis, with dominance shifting to the cyanobacterium Synechococcus (up to 33 ppm in April), an algal group that comprised a minor bloom component on May 28. Thus, unlike the brown tide bloom in Laguna Madre, which lasted 8 years, the bloom in Guantánamo Bay was short-lived, much like recent blooms in the Indian River, Florida. Although hypersaline conditions have been linked to brown tide development in the lagoons of Texas and Florida, observed euhaline conditions in Guantánamo Bay (salinity 35–36) indicate that strong hypersalinity is not a requirement for A. lagunensis bloom formation. Microzooplankton biomass dominated by ciliates was high during the observed peak of the brown tide, and ciliate abundance was high compared to other systems not impacted by brown tide. Preferential grazing by zooplankton on non-brown tide species, as shown in A. lagunensis blooms in Texas and Florida, may have been a factor in the development of the Cuban brown tide bloom. However, subsequent selection of microzooplankton capable of utilizing A. lagunensis as a primary food source may have contributed to the

  11. Hijacking host cell highways: manipulation of the host actin cytoskeleton by obligate intracellular bacterial pathogens

    Directory of Open Access Journals (Sweden)

    Punsiri M Colonne

    2016-09-01

    Full Text Available Intracellular bacterial pathogens replicate within eukaryotic cells and display unique adaptations that support key infection events including invasion, replication, immune evasion, and dissemination. From invasion to dissemination, all stages of the intracellular bacterial life cycle share the same three-dimensional cytosolic space containing the host cytoskeleton. For successful infection and replication, many pathogens hijack the cytoskeleton using effector proteins introduced into the host cytosol by specialized secretion systems. A subset of effectors contains eukaryotic-like motifs that mimic host proteins to exploit signaling and modify specific cytoskeletal components such as actin and microtubules. Cytoskeletal rearrangement promotes numerous events that are beneficial to the pathogen, including internalization of bacteria, subversion of cell intrinsic immunity, structural support for bacteria-containing vacuoles, altered vesicular trafficking, actin-dependent bacterial movement, and pathogen dissemination. This review highlights a diverse group of obligate intracellular bacterial pathogens that manipulate the host cytoskeleton to thrive within eukaryotic cells and discusses underlying molecular mechanisms that promote these dynamic host-pathogen interactions.

  12. The Costs of Respiratory Illnesses Arising from Florida Gulf Coast Karenia brevis Blooms

    Science.gov (United States)

    Hoagland, Porter; Jin, Di; Polansky, Lara Y.; Kirkpatrick, Barbara; Kirkpatrick, Gary; Fleming, Lora E.; Reich, Andrew; Watkins, Sharon M.; Ullmann, Steven G.; Backer, Lorraine C.

    2009-01-01

    Background Algal blooms of Karenia brevis, a harmful marine algae, occur almost annually off the west coast of Florida. At high concentrations, K. brevis blooms can cause harm through the release of potent toxins, known as brevetoxins, to the atmosphere. Epidemiologic studies suggest that aerosolized brevetoxins are linked to respiratory illnesses in humans. Objectives We hypothesized a relationship between K. brevis blooms and respiratory illness visits to hospital emergency departments (EDs) while controlling for environmental factors, disease, and tourism. We sought to use this relationship to estimate the costs of illness associated with aerosolized brevetoxins. Methods We developed a statistical exposure–response model to express hypotheses about the relationship between respiratory illnesses and bloom events. We estimated the model with data on ED visits, K. brevis cell densities, and measures of pollen, pollutants, respiratory disease, and intra-annual population changes. Results We found that lagged K. brevis cell counts, low air temperatures, influenza outbreaks, high pollen counts, and tourist visits helped explain the number of respiratory-specific ED diagnoses. The capitalized estimated marginal costs of illness for ED respiratory illnesses associated with K. brevis blooms in Sarasota County, Florida, alone ranged from $0.5 to $4 million, depending on bloom severity. Conclusions Blooms of K. brevis lead to significant economic impacts. The costs of illness of ED visits are a conservative estimate of the total economic impacts. It will become increasingly necessary to understand the scale of the economic losses associated with K. brevis blooms to make rational choices about appropriate mitigation. PMID:19672403

  13. The sedimentary record of dinoflagellate cysts: looking back into the future of phytoplankton blooms

    Directory of Open Access Journals (Sweden)

    Barrie Dale

    2001-12-01

    Full Text Available Marine systems are not as well understood as terrestrial systems, and there is still a great need for more primary observations, in the tradition of the old-time naturalists, before newer methods such as molecular genetics and modeling can be fully utilized. The scientific process whereby the smaller, detailed building blocks of observation are ultimately linked towards better understanding natural systems is illustrated from my own career experience, especially with regard to the dinoflagellates and plankton blooms. Some dinoflagellates produce a fossilizable resting stage (cyst in their life cycle, and dinoflagellate cysts have become one of the most important groups of microfossils used in geological exploration (e.g. oil and gas. This has stimulated both paleontological and biological research producing detailed building blocks of information, currently scattered throughout the respective literature. Here, I attempt to bring together the present day perspective, from biology, with the past, from paleontology, as the most comprehensive basis for future work on the group. This shows the cysts to be the critical link needed for focusing future molecular genetics studies towards a more verifiable view of evolutionary pathways, and it also suggests new integrated methods for studying past, present, and future blooms. The large, rapidly growing field of harmful algal bloom studies is producing many different building blocks, but plankton blooms as episodic phenomena are still poorly understood. This is largely due to the general lack of long-term datasets allowing identification of the changing environmental factors that permit certain species to bloom at unpredictable intervals of time. Cysts in sediments are useful environmental indicators today, e.g. reflecting aspects of climate and pollution, and provide information directly relevant to some dinoflagellate blooms. They therefore may be used for obtaining retrospective information from the

  14. Algal blooms in the seas around India - Networking for research and outreach

    Digital Repository Service at National Institute of Oceanography (India)

    Bhat, S.R.; Matondkar, S.G.P.

    - eaters about the paralytic, neurotoxic and diarrhoetic e f fe cts due to the consumption of bloom - affected fish and shellfish 5 . The volunteers also assist marine research i n- stitutes with actual observed data and information. The research..., co l- lect and evaluate samples from the bloom - hit areas and assist the University of Delaware in issuing health alerts through the State department. The volunteers also supply algal samples for culture, since collecting samples...

  15. Successional trajectories of bacterioplankton community over the complete cycle of a sudden phytoplankton bloom in the Xiangshan Bay, East China Sea.

    Science.gov (United States)

    Chen, Heping; Zhang, Huajun; Xiong, Jinbo; Wang, Kai; Zhu, Jianlin; Zhu, Xiangyu; Zhou, Xiaoyan; Zhang, Demin

    2016-12-01

    Phytoplankton bloom has imposed ecological concerns worldwide; however, few studies have been focused on the successional trajectories of bacterioplankton community over a complete phytoplankton bloom cycle. Using 16S pyrosequencing, we investigated how the coastal bacterioplankton community compositions (BCCs) respond to a phytoplankton bloom in the Xiangshan Bay, East China Sea. The results showed that BCCs were significantly different among the pre-bloom, bloom, and after-bloom stages, with the lowest bacterial diversity at the bloom phase. The BCCs at the short-term after-bloom phase showed a rapid but incomplete recovery to the pre-bloom phase, evidenced by 69.8% similarity between pre-bloom and after-bloom communities. This recovery was parallel with the dynamics of the operational taxonomic units (OTUs) affiliated with Actinobacteria, Bacteroidetes, Cyanobacteria, Alphaproteobacteria and Gammaproteobacteria, whose abundance enriched when bloom occur, and decreased after-bloom, and vice versa. Collectively, the results showed that the BCCs were sensitive to algal-induced disturbances, but could recover to a certain extent after bloom. In addition, OTUs which enriched or decreased during this process are closely associated with this temporal pattern, thus holding the potential to evaluate and indicate the succession stage of phytoplankton bloom. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Mechanism of H. pylori intracellular entry: an in vitro study

    Directory of Open Access Journals (Sweden)

    Hui eLiu

    2012-03-01

    Full Text Available The majority of H. pylori reside on gastric epithelial cell surfaces and in the overlying mucus, but a small fraction of H. pylori enter host epithelial and immune cells. To explore the role of the nudA invasin in host cell entry, a ΔnudA deletion derivative of strain J99 was constructed and transformants were verified by PCR and by fluorescence in situ hybridization. AGS cells were inoculated with either wild type (WT strain J99 or its ΔnudA mutant to determine the fraction of bacteria that were bound to the cells and inside these cells using the gentamicin protection assay. We observed no significant difference between either the density of H. pylori bound to AGS cell membranes or the density of intracellular H. pylori. To further explore this finding, separate chambers of each culture were fixed in glutaraldehyde for transmission electron microscopy (TEM and immunogold TEM. This addition to the classical gentamicin assay demonstrated that there were significantly more intracellular, and fewer membrane-bound, H. pylori in WT-infected AGS cells than in ΔnudA allele infected cells. Thus, the sum of intracellular and membrane-bound H. pylori was similar in the two groups. Since no other similar TEM study has been performed, it is at present unknown whether our observations can be reproduced by others Taken together however, our observations suggest that the classical gentamicin protection assay is not sufficiently sensitive to analyze H. pylori cell entry and that the addition of TEM to the test demonstrate that nudA plays a role in H. pylori entry into AGS cells in vitro. In addition, deletion of the invasin gene appears to limit H. pylori to the AGS cell surface, where it may be partly protected against gentamicin. In contrast, this specific environment may render H. pylori more vulnerable to host defense and therapeutic intervention, and less prone to trigger normal immune, carcinogenic, and other developmental response pathways.

  17. Genomics of Probiotic Bacteria

    Science.gov (United States)

    O'Flaherty, Sarah; Goh, Yong Jun; Klaenhammer, Todd R.

    Probiotic bacteria from the Lactobacillus and Bifidobacterium species belong to the Firmicutes and the Actinobacteria phylum, respectively. Lactobacilli are members of the lactic acid bacteria (LAB) group, a broadly defined family of microorganisms that ferment various hexoses into primarily lactic acid. Lactobacilli are typically low G + C gram-positive species which are phylogenetically diverse, with over 100 species documented to date. Bifidobacteria are heterofermentative, high G + C content bacteria with about 30 species of bifidobacteria described to date.

  18. Mitigating Toxic Planktonic Cyanobacterial Blooms in Aquatic Ecosystems Facing Increasing Anthropogenic and Climatic Pressures

    Directory of Open Access Journals (Sweden)

    Hans W. Paerl

    2018-02-01

    Full Text Available Toxic planktonic cyanobacterial blooms are a pressing environmental and human health problem. Blooms are expanding globally and threatening sustainability of our aquatic resources. Anthropogenic nutrient enrichment and hydrological modifications, including water diversions and reservoir construction, are major drivers of bloom expansion. Climatic change, i.e., warming, more extreme rainfall events, and droughts, act synergistically with human drivers to exacerbate the problem. Bloom mitigation steps, which are the focus of this review, must consider these dynamic interactive factors in order to be successful in the short- and long-term. Furthermore, these steps must be applicable along the freshwater to marine continuum connecting streams, lakes, rivers, estuarine, and coastal waters. There is an array of physical, chemical, and biological approaches, including flushing, mixing, dredging, application of algaecides, precipitating phosphorus, and selective grazing, that may arrest and reduce bloom intensities in the short-term. However, to ensure long term, sustainable success, targeting reductions of both nitrogen and phosphorus inputs should accompany these approaches along the continuum. Lastly, these strategies should accommodate climatic variability and change, which will likely modulate and alter nutrient-bloom thresholds.

  19. Factors affecting outbreaks of Cochlodinium polykrikoides blooms in coastal areas of Korea

    International Nuclear Information System (INIS)

    Lee, Young Sik . E-mail leeyodk@hanmail.net; Lee, Sang Yong

    2006-01-01

    We evaluated the causes of the first outbreak of Cochlodinium polykrikoides blooms in Narodo and the Southern coast of Namhaedo on the South Sea, as well as the outbreak of C. polykrikoides blooms in the East Sea and around Wando. From the results of AGP tests using diverse seawater types, we identified seawaters in which C. polykrikoides grow well and those in which they do not, depending on the sampling time and location. The reason for C. polykrikoides blooms initially occurring in Narodo, Namhaedo, and Gujaedo seems to be because the seawater that promotes the growth of C. polykrikoides is transported to the areas of primary generation, such as these three areas, by the influence of the Tsushima Warm Current. The reason that C. polykrikoides blooms occur in the coastal area of Wando and the East Sea is because after the seawater promoting the growth of C. polykrikoides is transported to these areas, the amount of sun radiation increases, and abundant nutrients flow in from heavy rains, resulting in mass propagation of C. polykrikoides. The origin of the seawater that promotes the growth of C. polykrikoides is assumed to be the southern section of the southern coastal area of Narodo, Namhaedo, and Gujaedo, in which C. polykrikoides blooms were initially discovered. The components of the f/2 medium (N, P, Fe, Mn, Co, Cu, Zn, Mo, B12, biotin, thiamine) do not seem to trigger the occurrence of C. polykrikoides blooms

  20. Diversity and dynamics of a widespread bloom of the toxic dinoflagellate Alexandrium fundyense.

    Directory of Open Access Journals (Sweden)

    Deana L Erdner

    Full Text Available Historically, cosmopolitan phytoplankton species were presumed to represent largely unstructured populations. However, the recent development of molecular tools to examine genetic diversity have revealed differences in phytoplankton taxa across geographic scales and provided insight into the physiology and ecology of blooms. Here we describe the genetic analysis of an extensive bloom of the toxic dinoflagellate Alexandrium fundyense that occurred in the Gulf of Maine in 2005. This bloom was notable for its intensity and duration, covering hundreds of kilometers and persisting for almost two months. Genotypic analyses based on microsatellite marker data indicate that the open waters of the northeastern U.S. harbor a single regional population of A. fundyense comprising two genetically distinct sub-populations. These subpopulations were characteristic of early- and late-bloom samples and were derived from the northern and southern areas of the bloom, respectively. The temporal changes observed during this study provide clear evidence of succession during a continuous bloom and show that selection can act on the timescale of weeks to significantly alter the representation of genotypes within a population. The effects of selection on population composition and turnover would be magnified if sexual reproduction were likewise influenced by environmental conditions. We hypothesize that the combined effects of differential growth and reproduction rates serves to reduce gene flow between the sub-populations, reinforcing population structure while maintaining the diversity of the overall regional population.

  1. Trade-Offs of Escherichia coli Adaptation to an Intracellular Lifestyle in Macrophages.

    Directory of Open Access Journals (Sweden)

    M Azevedo

    Full Text Available The bacterium Escherichia coli exhibits remarkable genomic and phenotypic variation, with some pathogenic strains having evolved to survive and even replicate in the harsh intra-macrophage environment. The rate and effects of mutations that can cause pathoadaptation are key determinants of the pace at which E. coli can colonize such niches and become pathogenic. We used experimental evolution to determine the speed and evolutionary paths undertaken by a commensal strain of E. coli when adapting to intracellular life. We estimated the acquisition of pathoadaptive mutations at a rate of 10-6 per genome per generation, resulting in the fixation of more virulent strains in less than a hundred generations. Whole genome sequencing of independently evolved clones showed that the main targets of intracellular adaptation involved loss of function mutations in genes implicated in the assembly of the lipopolysaccharide core, iron metabolism and di- and tri-peptide transport, namely rfaI, fhuA and tppB, respectively. We found a substantial amount of antagonistic pleiotropy in evolved populations, as well as metabolic trade-offs, commonly found in intracellular bacteria with reduced genome sizes. Overall, the low levels of clonal interference detected indicate that the first steps of the transition of a commensal E. coli into intracellular pathogens are dominated by a few pathoadaptive mutations with very strong effects.

  2. Epigenetic silencing of host cell defense genes enhances intracellular survival of the rickettsial pathogen Anaplasma phagocytophilum.

    Directory of Open Access Journals (Sweden)

    Jose C Garcia-Garcia

    2009-06-01

    Full Text Available Intracellular bacteria have evolved mechanisms that promote survival within hostile host environments, often resulting in functional dysregulation and disease. Using the Anaplasma phagocytophilum-infected granulocyte model, we establish a link between host chromatin modifications, defense gene transcription and intracellular bacterial infection. Infection of THP-1 cells with A. phagocytophilum led to silencing of host defense gene expression. Histone deacetylase 1 (HDAC1 expression, activity and binding to the defense gene promoters significantly increased during infection, which resulted in decreased histone H3 acetylation in infected cells. HDAC1 overexpression enhanced infection, whereas pharmacologic and siRNA HDAC1 inhibition significantly decreased bacterial load. HDAC2 does not seem to be involved, since HDAC2 silencing by siRNA had no effect on A. phagocytophilum intracellular propagation. These data indicate that HDAC up-regulation and epigenetic silencing of host cell defense genes is required for A. phagocytophilum infection. Bacterial epigenetic regulation of host cell gene transcription could be a general mechanism that enhances intracellular pathogen survival while altering cell function and promoting disease.

  3. Temporal Dynamics of the Microbial Community Composition with a Focus on Toxic Cyanobacteria and Toxin Presence during Harmful Algal Blooms in Two South German Lakes

    Directory of Open Access Journals (Sweden)

    Pia I. Scherer

    2017-12-01

    Full Text Available Bacterioplankton plays an essential role in aquatic ecosystems, and cyanobacteria are an influential part of the microbiome in many water bodies. In freshwaters used for recreational activities or drinking water, toxic cyanobacteria cause concerns due to the risk of intoxication with cyanotoxins, such as microcystins. In this study, we aimed to unmask relationships between toxicity, cyanobacterial community composition, and environmental factors. At the same time, we assessed the correlation of a genetic marker with microcystin concentration and aimed to identify the main microcystin producer. We used Illumina MiSeq sequencing to study the bacterioplankton in two recreational lakes in South Germany. We quantified a microcystin biosynthesis gene (mcyB using qPCR and linked this information with microcystin concentration to assess toxicity. Microcystin biosynthesis gene (mcyE-clone libraries were used to determine the origin of microcystin biosynthesis genes. Bloom toxicity did not alter the bacterial community composition, which was highly dynamic at the lowest taxonomic level for some phyla such as Cyanobacteria. At the OTU level, we found distinctly different degrees of temporal variation between major bacteria phyla. Cyanobacteria and Bacteroidetes showed drastic temporal changes in their community compositions, while the composition of Actinobacteria remained rather stable in both lakes. The bacterial community composition of Alpha- and Beta-proteobacteria remained stable over time in Lake Klostersee, but it showed temporal variations in Lake Bergknappweiher. The presence of potential microcystin degraders and potential algicidal bacteria amongst prevalent Bacteroidetes and Alphaproteobacteria implied a role of those co-occurring heterotrophic bacteria in cyanobacterial bloom dynamics. Comparison of both lakes studied revealed a large shared microbiome, which was shaped toward the lake specific community composition by environmental factors

  4. Subversion of inflammasome activation and pyroptosis by pathogenic bacteria

    Directory of Open Access Journals (Sweden)

    Larissa D Cunha

    2013-11-01

    Full Text Available Activation of the inflammasome occurs in response to a notably high number of pathogenic microbes and is a broad innate immune response that effectively contributes to restriction of pathogen replication and generation of adaptive immunity. Activation of these platforms leads to caspase-1- and/or caspase-11-dependent secretion of proteins, including cytokines, and induction of a specific form of cell death called pyroptosis, which directly or indirectly contribute for restriction of pathogen replication. Not surprisingly, bona fide intracellular pathogens developed strategies for manipulation of cell death to guarantee intracellular replication. In this sense, the remarkable advances in the knowledge of the inflammasome field have been accompanied by several reports characterizing the inhibition of this platform by several pathogenic bacteria. Herein, we review some processes used by pathogenic bacteria, including Yersinia spp., Pseudomonas aeruginosa, Vibrio parahaemolyticus, Chlamydia trachomatis, Francisella tularensis, Shigella flexneri, Legionella pneumophila and Coxiella burnetii to evade the activation of the inflammasome and the induction of pyroptosis.

  5. Subversion of inflammasome activation and pyroptosis by pathogenic bacteria.

    Science.gov (United States)

    Cunha, Larissa D; Zamboni, Dario S

    2013-01-01

    Activation of the inflammasome occurs in response to a notably high number of pathogenic microbes and is a broad innate immune response that effectively contributes to restriction of pathogen replication and generation of adaptive immunity. Activation of these platforms leads to caspase-1- and/or caspase-11-dependent secretion of proteins, including cytokines, and induction of a specific form of cell death called pyroptosis, which directly or indirectly contribute for restriction of pathogen replication. Not surprisingly, bona fide intracellular pathogens developed strategies for manipulation of cell death to guarantee intracellular replication. In this sense, the remarkable advances in the knowledge of the inflammasome field have been accompanied by several reports characterizing the inhibition of this platform by several pathogenic bacteria. Herein, we review some processes used by pathogenic bacteria, including Yersinia spp., Pseudomonas aeruginosa, Vibrio parahaemolyticus, Chlamydia trachomatis, Francisella tularensis, Shigella flexneri, Legionella pneumophila, and Coxiella burnetii to evade the activation of the inflammasome and the induction of pyroptosis.

  6. Effects of thermal blooming on systems comprised of tiled subapertures

    Science.gov (United States)

    Leakeas, Charles L.; Bartell, Richard J.; Krizo, Matthew J.; Fiorino, Steven T.; Cusumano, Salvatore J.; Whiteley, Matthew R.

    2010-04-01

    Laser weapon systems comprise of tiled subapertures are rapidly emerging in the directed energy community. The Air Force Institute of Technology Center for Directed Energy (AFIT/CDE), under sponsorship of the HEL Joint Technology Office has developed performance models of such laser weapon system configurations consisting of tiled arrays of both slab and fiber subapertures. These performance models are based on results of detailed waveoptics analyses conducted using WaveTrain. Previous performance model versions developed in this effort represent system characteristics such as subaperture shape, aperture fill factor, subaperture intensity profile, subaperture placement in the primary aperture, subaperture mutual coherence (piston), subaperture differential jitter (tilt), and beam quality wave-front error associated with each subaperture. The current work is a prerequisite for the development of robust performance models for turbulence and thermal blooming effects for tiled systems. Emphasis is placed on low altitude tactical scenarios. The enhanced performance model developed will be added to AFIT/CDE's HELEEOS parametric one-on-one engagement level model via the Scaling for High Energy Laser and Relay Engagement (SHaRE) toolbox.

  7. Síndrome de Bloom: relato de dois casos

    Directory of Open Access Journals (Sweden)

    Aline Salmito Frota

    2015-06-01

    Full Text Available Síndrome de Bloom é uma doença autossômica recessiva caracterizada por eritema telangiectásico em face, fotossensibilidade e retardo de crescimento pré e pós-natal. A mutação do gene BLM, traz uma instabilidade cromossômica importante, responsável pelas manifestações da síndrome e pela maior susceptibilidade a neoplasias. Há um registro mundial de pacientes com um total de 255 casos, sendo 16 do Brasil. Diante da raridade da síndrome, apresentamos o caso de duas irmãs, filhas de pais consanguíneos, ambas com baixa estatura, apresentando máculas eritematosas com telangiectasias em nariz e região perioral, micrognatismo, dolicocefalia, hipoplasia malar, face triangular, nariz proeminente, máculas hipocrômicas e manchas café com leite em tronco e membros inferiores. O diagnóstico é clínico e pode ser confirmado por citogenética. Os portadores apresentam fenótipo típico com telangiectasias em áreas fotoexpostas. Ainda não há tratamento específico, porém, deve-se oferecer suporte clínico e melhoria da qualidade de vida e diminuição de estigmas.

  8. Then the Wilderness Shall Bloom like a Rosy Bower

    DEFF Research Database (Denmark)

    Nielsen, Kirsten

    2014-01-01

    In his article “The holy Road as a Bridge: The Role of Chapter 35 in the Book of Isaiah”, Hallvard Hagelia has demonstrated the intertextual connections between Isa 35 and the rest of the book. According to Hagelia, the animal motive plays a very small part in Isa 35, although he points at various...... the same function. They are metaphors for Israel's enemies (cf. Isa 34 and 36-39). The animal motive is therefore part of the bridge made by Isa 35. My analysis thereby strengthens Hallvard Hagelia's arguments for seeing Isa 35 as a bridge in the Book of Isaiah....... intertextual connections to the rest of the book. In my article, I have analysed how the Danish poet N.F.S. Grundtvig reworks Isa 35 in his hymn “Then the wilderness shall bloom like a rosy bower”, and how he reinterprets the wild animals as the Enemy (the Devil). In my view, the animals in Isa 35 have...

  9. Reduction of intracellular glutathione content and radiosensitivity

    International Nuclear Information System (INIS)

    Vos, O.; Schans, G.P. van der; Roos-Verheij, W.S.D.

    1986-01-01

    The intracellular glutathione (GSH) content of HeLa, CHO and V79 cells was reduced by incubating the cells in growth medium containing buthionine sulphoximine or diethyl maleate (DEM). Clonogenicity, single-strand DNA breaks (ssb) and double-strand DNA breaks (dsb) were used as criteria for radiation-induced damage after X- or γ-irradiation. In survival experiments, DEM gave a slightly larger sensitization although it gave a smaller reduction of the intracellular GSH. In general, sensitization was larger for dsb than for ssb, also the reduction of the o.e.r. was generally larger for dsb than for ssb. This may be due to the higher dose rate in case of dsb experiments resulting in a higher rate of radiochemical oxygen consumption. In general, no effect was found on post-irradiation repair of ssb and dsb. (author)

  10. Intracellular mechanisms of solar water disinfection

    Science.gov (United States)

    Castro-Alférez, María; Polo-López, María Inmaculada; Fernández-Ibáñez, Pilar

    2016-12-01

    Solar water disinfection (SODIS) is a zero-cost intervention measure to disinfect drinking water in areas of poor access to improved water sources, used by more than 6 million people in the world. The bactericidal action of solar radiation in water has been widely proven, nevertheless the causes for this remain still unclear. Scientific literature points out that generation of reactive oxygen species (ROS) inside microorganisms promoted by solar light absorption is the main reason. For the first time, this work reports on the experimental measurement of accumulated intracellular ROS in E. coli during solar irradiation. For this experimental achievement, a modified protocol based on the fluorescent probe dichlorodihydrofluorescein diacetate (DCFH-DA), widely used for oxidative stress in eukaryotic cells, has been tested and validated for E. coli. Our results demonstrate that ROS and their accumulated oxidative damages at intracellular level are key in solar water disinfection.

  11. Reduction of intracellular glutathione content and radiosensitivity

    International Nuclear Information System (INIS)

    Vos, O.; Schans, G.P. van der; Roos-Verheij, W.S.D.

    1986-05-01

    The intracellular glutathione (GSH) content in HeLa, CHO and V79 cells was reduced by incubating the cells in growth medium containing buthionine sulfoximine (BSO) or diethyl maleate (DEM). Clonogenicity, single strand DNA breaks (ssb) and double strand DNA breaks (dsb) were used as criteria for radiation induced damage after X- or γ irradiation. In survival experiments DEM gave a slightly larger sensitization although it gave a smaller reduction of the intracellular GSH. In general, sensitization was larger for dsb than for ssb, also the reduction of the OER was generally larger for dsb than for ssb. This may be due to the higher dose rate in case of dsb experiments resulting in a higher rate of radiochemical oxygen consumption. In general, no effect was found on post-irradiation repair of ssb and dsb. (Auth.)

  12. Structural Dynamics of Community Gene Expression In a Freshwater Cyanobacterial Bloom Over a Day-Night Cycle

    Science.gov (United States)

    Wang, J.; Fernando, S.; Thompson, J. R.

    2011-12-01

    Cyanobacterial blooms are a major problem in eutrophic lakes and reservoirs, negatively impacting the ecology of the water body through oxygen depletion upon bloom decay and in some cases through production of toxins. Waterborne cyanobacterial toxins pose a public health threat through drinking and recreational exposure. The frequency of harmful cyanobacterial blooms (cyanoHABs) is predicted to increase due to warming regional climates (Paerl et.al, 2011) and increases in non-point source pollution due to urban expansion (Novotny, 2011). CyanoHABs represent complex consortia of cyanobacteria that live in association with diverse assemblages of heterotrophic and anoxygenic photosynthetic bacteria. A better understanding of the structure, function, and interaction between members of the complex microbial communities that support the proliferation of toxigenic cyanobacteria will improve our ability to prevent and control cyanoHABs. Studies of community gene expression, or metatranscriptomics, provide a powerful approach for quantifying changes in both the taxonomic composition (structure) and activity (function) of complex microbial systems in response to dynamic environmental conditions. We have used next-generation Illumina sequencing to characterize the metatranscriptome of a tropical eutrophic drinking water reservoir dominated by the toxigenic cyanobacterium Microcystis aeruginosa over a day/night cycle. Bacterioplankton sampling was carried out at six time points over a 24 hour period to capture variability associated with changes in the balance between phototrophic and heterotrophic activity. Total RNA was extracted and subjected to ribosomal depletion followed by cDNA synthesis and sequencing, generating 493,468 to 678,064 95-101 bp post-quality control reads per sample. Hierarchical Clustering of transcriptional profiles supported sorting of samples into two clusters corresponding to "day" and "night" collection times. Annotation of reads through the MG

  13. Swedish isolates of Vibrio cholerae enhance their survival when interacted intracellularly with Acanthamoeba castellanii

    Science.gov (United States)

    Shanan, Salah; Bayoumi, Magdi; Saeed, Amir; Sandström, Gunnar; Abd, Hadi

    2016-01-01

    Vibrio cholerae is a Gram-negative bacterium that occurs naturally in aquatic environment. Only V. cholerae O1 and V. cholerae O139 produce cholera toxin and cause cholera, other serogroups can cause gastroenteritis, open wounds infection, and septicaemia. V. cholerae O1 and V. cholerae O139 grow and survive inside Acanthamoeba castellanii. The aim of this study is to investigate the interactions of the Swedish clinical isolates V. cholerae O3, V. cholerae O4, V. cholerae O5, V. cholerae O11, and V. cholerae O160 with A. castellanii. The interaction between A. castellanii and V. cholerae strains was studied by means of amoeba cell counts, viable counts of the bacteria in the absence or presence of amoebae, and of the intracellularly growing bacteria, visualised by electron microscopy. These results show that all V. cholerae can grow and survive outside and inside the amoebae, disclosing that V. cholerae O3, V. cholerae O4, V. cholerae O5, V. cholerae O11, and V. cholerae O160 all can be considered as facultative intracellular bacteria. PMID:27118300

  14. Swedish isolates of Vibrio cholerae enhance their survival when interacted intracellularly with Acanthamoeba castellanii

    Directory of Open Access Journals (Sweden)

    Salah Shanan

    2016-04-01

    Full Text Available Vibrio cholerae is a Gram-negative bacterium that occurs naturally in aquatic environment. Only V. cholerae O1 and V. cholerae O139 produce cholera toxin and cause cholera, other serogroups can cause gastroenteritis, open wounds infection, and septicaemia. V. cholerae O1 and V. cholerae O139 grow and survive inside Acanthamoeba castellanii. The aim of this study is to investigate the interactions of the Swedish clinical isolates V. cholerae O3, V. cholerae O4, V. cholerae O5, V. cholerae O11, and V. cholerae O160 with A. castellanii. The interaction between A. castellanii and V. cholerae strains was studied by means of amoeba cell counts, viable counts of the bacteria in the absence or presence of amoebae, and of the intracellularly growing bacteria, visualised by electron microscopy. These results show that all V. cholerae can grow and survive outside and inside the amoebae, disclosing that V. cholerae O3, V. cholerae O4, V. cholerae O5, V. cholerae O11, and V. cholerae O160 all can be considered as facultative intracellular bacteria.

  15. Intracellular Protein Delivery for Treating Breast Cancer

    Science.gov (United States)

    2014-08-01

    Intracellular delivery of such proteins, including human tumor suppressors (such as p53) (Brown et al., 2009) and exogenous tumor-killing proteins...vivo systems. Nature materials 11, 1038-1043. Chorny, M., Hood, E., Levy, R.J., and Muzykantov, V.R. (2010). Endothelial delivery of antioxidant ...for the ntracellular delivery of such proteins, including human umor suppressors [7] and exogenous tumor-killing proteins 8—10]), is attractive as a

  16. Genome expression analysis of nonproliferating intracellular Salmonella enterica serovar Typhimurium unravels an acid pH-dependent PhoP-PhoQ response essential for dormancy.

    Science.gov (United States)

    Núñez-Hernández, Cristina; Tierrez, Alberto; Ortega, Alvaro D; Pucciarelli, M Graciela; Godoy, Marta; Eisman, Blanca; Casadesús, Josep; García-del Portillo, Francisco

    2013-01-01

    Genome-wide expression analyses have provided clues on how Salmonella proliferates inside cultured macrophages and epithelial cells. However, in vivo studies show that Salmonella does not replicate massively within host cells, leaving the underlying mechanisms of such growth control largely undefined. In vitro infection models based on fibroblasts or dendritic cells reveal limited proliferation of the pathogen, but it is presently unknown whether these phenomena reflect events occurring in vivo. Fibroblasts are distinctive, since they represent a nonphagocytic cell type in which S. enterica serovar Typhimurium actively attenuates intracellular growth. Here, we show in the mouse model that S. Typhimurium restrains intracellular growth within nonphagocytic cells positioned in the intestinal lamina propria. This response requires a functional PhoP-PhoQ system and is reproduced in primary fibroblasts isolated from the mouse intestine. The fibroblast infection model was exploited to generate transcriptome data, which revealed that ∼2% (98 genes) of the S. Typhimurium genome is differentially expressed in nongrowing intracellular bacteria. Changes include metabolic reprogramming to microaerophilic conditions, induction of virulence plasmid genes, upregulation of the pathogenicity islands SPI-1 and SPI-2, and shutdown of flagella production and chemotaxis. Comparison of relative protein levels of several PhoP-PhoQ-regulated functions (PagN, PagP, and VirK) in nongrowing intracellular bacteria and extracellular bacteria exposed to diverse PhoP-PhoQ-inducing signals denoted a regulation responding to acidic pH. These data demonstrate that S. Typhimurium restrains intracellular growth in vivo and support a model in which dormant intracellular bacteria could sense vacuolar acidification to stimulate the PhoP-PhoQ system for preventing intracellular overgrowth.

  17. Genome Expression Analysis of Nonproliferating Intracellular Salmonella enterica Serovar Typhimurium Unravels an Acid pH-Dependent PhoP-PhoQ Response Essential for Dormancy

    Science.gov (United States)

    Núñez-Hernández, Cristina; Tierrez, Alberto; Ortega, Álvaro D.; Pucciarelli, M. Graciela; Godoy, Marta; Eisman, Blanca; Casadesús, Josep

    2013-01-01

    Genome-wide expression analyses have provided clues on how Salmonella proliferates inside cultured macrophages and epithelial cells. However, in vivo studies show that Salmonella does not replicate massively within host cells, leaving the underlying mechanisms of such growth control largely undefined. In vitro infection models based on fibroblasts or dendritic cells reveal limited proliferation of the pathogen, but it is presently unknown whether these phenomena reflect events occurring in vivo. Fibroblasts are distinctive, since they represent a nonphagocytic cell type in which S. enterica serovar Typhimurium actively attenuates intracellular growth. Here, we show in the mouse model that S. Typhimurium restrains intracellular growth within nonphagocytic cells positioned in the intestinal lamina propria. This response requires a functional PhoP-PhoQ system and is reproduced in primary fibroblasts isolated from the mouse intestine. The fibroblast infection model was exploited to generate transcriptome data, which revealed that ∼2% (98 genes) of the S. Typhimurium genome is differentially expressed in nongrowing intracellular bacteria. Changes include metabolic reprogramming to microaerophilic conditions, induction of virulence plasmid genes, upregulation of the pathogenicity islands SPI-1 and SPI-2, and shutdown of flagella production and chemotaxis. Comparison of relative protein levels of several PhoP-PhoQ-regulated functions (PagN, PagP, and VirK) in nongrowing intracellular bacteria and extracellular bacteria exposed to diverse PhoP-PhoQ-inducing signals denoted a regulation responding to acidic pH. These data demonstrate that S. Typhimurium restrains intracellular growth in vivo and support a model in which dormant intracellular bacteria could sense vacuolar acidification to stimulate the PhoP-PhoQ system for preventing intracellular overgrowth. PMID:23090959

  18. Free-Living Amoebae as Hosts for and Vectors of Intracellular Microorganisms with Public Health Significance

    Science.gov (United States)

    Balczun, Carsten; Scheid, Patrick L.

    2017-01-01

    Free-living amoebae (FLA) are parasites within both humans and animals causing a wide range of symptoms and act as hosts of, and vehicles for phylogenetically diverse microorganisms, called endocytobionts. The interaction of the FLA with sympatric microorganisms leads to an exceptional diversity within FLA. Some of these bacteria, viruses, and even eukaryotes, can live and replicate intracellularly within the FLA. This relationship provides protection to the microorganisms from external interventions and a dispersal mechanism across various habitats. Among those intracellularly-replicating or -residing organisms there are obligate and facultative pathogenic microorganisms affecting the health of humans or animals and are therefore of interest to Public Health Authorities. Mimiviruses, Pandoraviruses, and Pithoviruses are examples for interesting viral endocytobionts within FLA. Future research is expected to reveal further endocytobionts within free-living amoebae and other protozoa through co-cultivation studies, genomic, transcriptomic, and proteomic analyses. PMID:28368313

  19. Role of Diatoms in the Spatial-Temporal Distribution of Intracellular Nitrate in Intertidal Sediment

    DEFF Research Database (Denmark)

    Stief, P.; Kamp, A.; de Beer, D.

    2013-01-01

    Intracellular nitrate storage allows microorganisms to survive fluctuating nutrient availability and anoxic conditions in aquatic ecosystems. Here we show that diatoms, ubiquitous and highly abundant microalgae, represent major cellular reservoirs of nitrate in an intertidal flat of the German...... Wadden Sea and are potentially involved in anaerobic nitrate respiration. Intracellular nitrate (ICNO3) was present year-round in the sediment and was spatially and temporally correlated with fucoxanthin, the marker photopigment of diatoms. Pyrosequencing of SSU rRNA genes of all domains of life...... confirmed that ICNO3 storage was most likely due to diatoms rather than other known nitrate-storing microorganisms (i.e., large sulfur bacteria and the eukaryotic foraminifers and gromiids). Sedimentary ICNO3 concentrations reached up to 22.3 mu mol dm(-3) at the sediment surface and decreased with sediment...

  20. An intracellular replication niche for Vibrio cholerae in the amoeba Acanthamoeba castellanii.

    Science.gov (United States)

    Van der Henst, Charles; Scrignari, Tiziana; Maclachlan, Catherine; Blokesch, Melanie

    2016-04-01

    Vibrio cholerae is a human pathogen and the causative agent of cholera. The persistence of this bacterium in aquatic environments is a key epidemiological concern, as cholera is transmitted through contaminated water. Predatory protists, such as amoebae, are major regulators of bacterial populations in such environments. Therefore, we investigated the interaction between V. cholerae and the amoeba Acanthamoeba castellanii at the single-cell level. We observed that V. cholerae can resist intracellular killing. The non-digested bacteria were either released or, alternatively, established a replication niche within the contractile vacuole of A. castellanii. V. cholerae was maintained within this compartment even upon encystment. The pathogen ultimately returned to its aquatic habitat through lysis of A. castellanii, a process that was dependent on the production of extracellular polysaccharide by the pathogen. This study reinforces the concept that V. cholerae is a facultative intracellular bacterium and describes a new host-pathogen interaction.

  1. Massive Regime Shifts and High Activity of Heterotrophic Bacteria in an Ice-Covered Lake

    Science.gov (United States)

    Bižić-Ionescu, Mina; Amann, Rudolf; Grossart, Hans-Peter

    2014-01-01

    In winter 2009/10, a sudden under-ice bloom of heterotrophic bacteria occurred in the seasonally ice-covered, temperate, deep, oligotrophic Lake Stechlin (Germany). Extraordinarily high bacterial abundance and biomass were fueled by the breakdown of a massive bloom of Aphanizomenon flos-aquae after ice formation. A reduction in light resulting from snow coverage exerted a pronounced physiological stress on the cyanobacteria. Consequently, these were rapidly colonized, leading to a sudden proliferation of attached and subsequently of free-living heterotrophic bacteria. Total bacterial protein production reached 201 µg C L−1 d−1, ca. five times higher than spring-peak values that year. Fluorescence in situ hybridization and denaturing gradient gel electrophoresis at high temporal resolution showed pronounced changes in bacterial community structure coinciding with changes in the physiology of the cyanobacteria. Pyrosequencing of 16S rRNA genes revealed that during breakdown of the cyanobacterial population, the diversity of attached and free-living bacterial communities were reduced to a few dominant families. Some of these were not detectable during the early stages of the cyanobacterial bloom indicating that only specific, well adapted bacterial communities can colonize senescent cyanobacteria. Our study suggests that in winter, unlike commonly postulated, carbon rather than temperature is the limiting factor for bacterial growth. Frequent phytoplankton blooms in ice-covered systems highlight the need for year-round studies of aquatic ecosystems including the winter season to correctly understand element and energy cycling through aquatic food webs, particularly the microbial loop. On a global scale, such knowledge is required to determine climate change induced alterations in carbon budgets in polar and temperate aquatic systems. PMID:25419654

  2. Fluorescent nanoparticles for intracellular sensing: A review

    International Nuclear Information System (INIS)

    Ruedas-Rama, Maria J.; Walters, Jamie D.; Orte, Angel; Hall, Elizabeth A.H.

    2012-01-01

    Highlights: ► Analytical applications of fluorescent nanoparticles (NPs) in intracellular sensing. ► Critical review on performance of QDots, metal NPs, silica NPs, and polymer NPs. ► Highlighted potential of fluorescence lifetime imaging microscopy (FLIM). - Abstract: Fluorescent nanoparticles (NPs), including semiconductor NPs (Quantum Dots), metal NPs, silica NPs, polymer NPs, etc., have been a major focus of research and development during the past decade. The fluorescent nanoparticles show unique chemical and optical properties, such as brighter fluorescence, higher photostability and higher biocompatibility, compared to classical fluorescent organic dyes. Moreover, the nanoparticles can also act as multivalent scaffolds for the realization of supramolecular assemblies, since their high surface to volume ratio allow distinct spatial domains to be functionalized, which can provide a versatile synthetic platform for the implementation of different sensing schemes. Their excellent properties make them one of the most useful tools that chemistry has supplied to biomedical research, enabling the intracellular monitoring of many different species for medical and biological purposes. In this review, we focus on the developments and analytical applications of fluorescent nanoparticles in chemical and biological sensing within the intracellular environment. The review also points out the great potential of fluorescent NPs for fluorescence lifetime imaging microscopy (FLIM). Finally, we also give an overview of the current methods for delivering of fluorescent NPs into cells, where critically examine the benefits and liabilities of each strategy.

  3. Fluorescent nanoparticles for intracellular sensing: A review

    Energy Technology Data Exchange (ETDEWEB)

    Ruedas-Rama, Maria J., E-mail: mjruedas@ugr.esmailto [Department of Physical Chemistry, Faculty of Pharmacy, University of Granada, Campus Cartuja, 18071, Granada (Spain); Walters, Jamie D. [Department of Chemical Engineering and Biotechnology, University of Cambridge, Tennis Court Road, Cambridge, UK CB2 1QT (United Kingdom); Orte, Angel [Department of Physical Chemistry, Faculty of Pharmacy, University of Granada, Campus Cartuja, 18071, Granada (Spain); Hall, Elizabeth A.H., E-mail: lisa.hall@biotech.cam.ac.uk [Department of Chemical Engineering and Biotechnology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QT (United Kingdom)

    2012-11-02

    Highlights: Black-Right-Pointing-Pointer Analytical applications of fluorescent nanoparticles (NPs) in intracellular sensing. Black-Right-Pointing-Pointer Critical review on performance of QDots, metal NPs, silica NPs, and polymer NPs. Black-Right-Pointing-Pointer Highlighted potential of fluorescence lifetime imaging microscopy (FLIM). - Abstract: Fluorescent nanoparticles (NPs), including semiconductor NPs (Quantum Dots), metal NPs, silica NPs, polymer NPs, etc., have been a major focus of research and development during the past decade. The fluorescent nanoparticles show unique chemical and optical properties, such as brighter fluorescence, higher photostability and higher biocompatibility, compared to classical fluorescent organic dyes. Moreover, the nanoparticles can also act as multivalent scaffolds for the realization of supramolecular assemblies, since their high surface to volume ratio allow distinct spatial domains to be functionalized, which can provide a versatile synthetic platform for the implementation of different sensing schemes. Their excellent properties make them one of the most useful tools that chemistry has supplied to biomedical research, enabling the intracellular monitoring of many different species for medical and biological purposes. In this review, we focus on the developments and analytical applications of fluorescent nanoparticles in chemical and biological sensing within the intracellular environment. The review also points out the great potential of fluorescent NPs for fluorescence lifetime imaging microscopy (FLIM). Finally, we also give an overview of the current methods for delivering of fluorescent NPs into cells, where critically examine the benefits and liabilities of each strategy.

  4. A bacteriophage endolysin that eliminates intracellular streptococci.

    Science.gov (United States)

    Shen, Yang; Barros, Marilia; Vennemann, Tarek; Gallagher, D Travis; Yin, Yizhou; Linden, Sara B; Heselpoth, Ryan D; Spencer, Dennis J; Donovan, David M; Moult, John; Fischetti, Vincent A; Heinrich, Frank; Lösche, Mathias; Nelson, Daniel C

    2016-03-15

    PlyC, a bacteriophage-encoded endolysin, lyses Streptococcus pyogenes (Spy) on contact. Here, we demonstrate that PlyC is a potent agent for controlling intracellular Spy that often underlies refractory infections. We show that the PlyC holoenzyme, mediated by its PlyCB subunit, crosses epithelial cell membranes and clears intracellular Spy in a dose-dependent manner. Quantitative studies using model membranes establish that PlyCB interacts strongly with phosphatidylserine (PS), whereas its interaction with other lipids is weak, suggesting specificity for PS as its cellular receptor. Neutron reflection further substantiates that PlyC penetrates bilayers above a PS threshold concentration. Crystallography and docking studies identify key residues that mediate PlyCB-PS interactions, which are validated by site-directed mutagenesis. This is the first report that a native endolysin can traverse epithelial membranes, thus substantiating the potential of PlyC as an antimicrobial for Spy in the extracellular and intracellular milieu and as a scaffold for engineering other functionalities.

  5. Seed-vectored endophytic bacteria modulate development of rice seedlings.

    Science.gov (United States)

    Verma, S K; Kingsley, K; Irizarry, I; Bergen, M; Kharwar, R N; White, J F

    2017-06-01

    The aim of the present study was to evaluate the effects of the removal of indigenous bacteria from rice seeds on seedling growth and development. Here we report the presence of three indigenous endophytic bacteria in rice seeds that play important roles in modulating seedling development (shoot and root lengths, and formation of root hairs and secondary roots) and defence against pathogens. Seed-associated bacteria were removed using surface sterilization with NaOCl (bleach) followed by antibiotic treatment. When bacteria were absent, growth of seedlings in terms of root hair development and overall seedling size was less than that of seedlings that contained bacteria. Reactive oxygen staining of seedlings showed that endophytic bacteria became intracellular in root parenchyma cells and root hairs. Roots containing endophytic bacteria were seen to stain densely for reactive oxygen, while roots free of bacteria stained lightly for reactive oxygen. Bacteria were isolated and identified as Enterobacter asburiae (VWB1), Pantoea dispersa (VWB2) and Pseudomonas putida (VWB3) by 16S rDNA sequencing. Bacteria were found to produce indole acetic acid (auxins), inhibited the pathogen Fusarium oxysporum and solubilized phosphate. Reinoculation of bacteria onto seedlings derived from surface-disinfected rice and Bermuda grass seeds significantly restored seedling growth and development. Rice seeds harbour indigenous bacterial endophytes that greatly influence seedling growth and development, including root and shoot lengths, root hair formation and disease susceptibility of rice seedlings. This study shows that seeds of rice naturally harbour bacterial endophytes that play key roles in modulation of seedling development. © 2017 The Society for Applied Microbiology.

  6. Algicidal Effects of a Novel Marine Pseudoalteromonas Isolate (Class Proteobacteria, Gamma Subdivision) on Harmful Algal Bloom Species of the Genera Chattonella, Gymnodinium, and Heterosigma

    Science.gov (United States)

    Lovejoy, Connie; Bowman, John P.; Hallegraeff, Gustaaf M.

    1998-01-01

    During a bacterial survey of the Huon Estuary in southern Tasmania, Australia, we isolated a yellow-pigmented Pseudoalteromonas strain (class Proteobacteria, gamma subdivision), designated strain Y, that had potent algicidal effects on harmful algal bloom species. This organism was identified by 16S rRNA sequencing as a strain with close affinities to Pseudoalteromonas peptidysin. This bacterium caused rapid cell lysis and death (within 3 h) of gymnodinoids (including Gymnodinium catenatum) and raphidophytes (Chattonella marina and Heterosigma akashiwo). It caused ecdysis of armored dinoflagellates (e.g., Alexandrium catenella, Alexandrium minutum, and Prorocentrum mexicanum), but the algal cultures then recovered over the subsequent 24 h. Strain Y had no effect on a cryptomonad (Chroomonas sp.), a diatom (Skeletonema sp.), a cyanobacterium (Oscillatoria sp.), and two aplastidic protozoans. The algicidal principle of strain Y was excreted into the seawater medium and lost its efficacy after heating. Another common bacterial species, Pseudoalteromonas carrageenovora, was isolated at the same time and did not have these algicidal effects. The minimum concentrations of strain Y required to kill G. catenatum were higher than the mean concentrations found in nature under nonbloom conditions. However, the new bacterium showed a chemotactic, swarming behavior that resulted in localized high concentrations around target organisms. These observations imply that certain bacteria could play an important role in regulating the onset and development of harmful algal blooms. PMID:9687434

  7. How honey kills bacteria

    NARCIS (Netherlands)

    Kwakman, Paulus H. S.; te Velde, Anje A.; de Boer, Leonie; Speijer, Dave; Vandenbroucke-Grauls, Christina M. J. E.; Zaat, Sebastian A. J.

    2010-01-01

    With the rise in prevalence of antibiotic-resistant bacteria, honey is increasingly valued for its antibacterial activity. To characterize all bactericidal factors in a medical-grade honey, we used a novel approach of successive neutralization of individual honey bactericidal factors. All bacteria

  8. Monitoring of Harmful Algal Blooms through Drinking Water Treatment Facilities Located on Lake Erie in the 2014 and 2015 Bloom Seasons

    Science.gov (United States)

    A number of drinking water treatment plants on Lake Erie have supplied water samples on a monthly basis for analysis related to the occurrence of harmful algal blooms (HABs). General water quality parameters including total organic carbon (TOC), orthophosphate, and chlorophyll-A ...

  9. Real-Time monitoring of intracellular wax ester metabolism

    Directory of Open Access Journals (Sweden)

    Karp Matti

    2011-09-01

    Full Text Available Abstract Background Wax esters are industrially relevant molecules exploited in several applications of oleochemistry and food industry. At the moment, the production processes mostly rely on chemical synthesis from rather expensive starting materials, and therefore solutions are sought from biotechnology. Bacterial wax esters are attractive alternatives, and especially the wax ester metabolism of Acinetobacter sp. has been extensively studied. However, the lack of suitable tools for rapid and simple monitoring of wax ester metabolism in vivo has partly restricted the screening and analyses of potential hosts and optimal conditions. Results Based on sensitive and specific detection of intracellular long-chain aldehydes, specific intermediates of wax ester synthesis, bacterial luciferase (LuxAB was exploited in studying the wax ester metabolism in Acinetobacter baylyi ADP1. Luminescence was detected in the cultivation of the strain producing wax esters, and the changes in signal levels could be linked to corresponding cell growth and wax ester synthesis phases. Conclusions The monitoring system showed correlation between wax ester synthesis pattern and luminescent signal. The system shows potential for real-time screening purposes and studies on bacterial wax esters, revealing new aspects to dynamics and role of wax ester metabolism in bacteria.

  10. A winter dinoflagellate bloom drives high rates of primary production in a Patagonian fjord ecosystem

    Science.gov (United States)

    Montero, P.; Pérez-Santos, I.; Daneri, G.; Gutiérrez, M. H.; Igor, G.; Seguel, R.; Purdie, D.; Crawford, D. W.

    2017-12-01

    A dense winter bloom of the dinoflagellate Heterocapsa triquetra was observed at a fixed station (44°35.3‧S; 72°43.6‧W) in the Puyuhuapi Fjord in Chilean Patagonia during July 2015. H. triquetra dominated the phytoplankton community in the surface waters between 2 and 15 m (13-58 × 109 cell m-2), with abundances some 3 to 15 times higher than the total abundance of the diatom assemblage, which was dominated by Skeletonema spp. The high abundance of dinoflagellates was reflected in high rates of gross primary production (GPP; 0.6-1.6 g C m-2 d-1) and chlorophyll-a concentration (Chl-a; 70-199.2 mg m-2) that are comparable to levels reported in spring diatom blooms in similar Patagonian fjords. We identify the main forcing factors behind a pulse of organic matter production during the non-productive winter season, and test the hypothesis that low irradiance levels are a key factor limiting phytoplankton blooms and subsequent productivity during winter. Principal Component Analysis (PCA) indicated that GPP rates were significantly correlated (r = -0.8, p < 0.05) with a decrease in salinity/temperature and the presence of the Heterocapsa bloom. The bloom occurred under low surface irradiance levels characteristic of austral winter and was accompanied by strong northern winds, associated with the passage of a low-pressure system, and a water column dominated by double diffusive layering. To our knowledge, this is the first report of a dense dinoflagellate bloom during deep austral winter in a Patagonian fjord, and our data challenge the paradigm of light limitation as a factor controlling phytoplankton blooms in this region in winter.

  11. Dissection of Microbial Community Functions during a Cyanobacterial Bloom in the Baltic Sea via Metatranscriptomics

    Directory of Open Access Journals (Sweden)

    Carlo Berg

    2018-02-01

    Full Text Available Marine and brackish surface waters are highly dynamic habitats that undergo repeated seasonal variations in microbial community composition and function throughout time. While succession of the various microbial groups has been well investigated, little is known about the underlying gene-expression of the microbial community. We investigated microbial interactions via metatranscriptomics over a spring to fall seasonal cycle in the brackish Baltic Sea surface waters, a temperate brackish water ecosystem periodically promoting massive cyanobacterial blooms, which have implications for primary production, nutrient cycling, and expansion of hypoxic zones. Network analysis of the gene expression of all microbes from 0.22 to 200 μm in size and of the major taxonomic groups dissected the seasonal cycle into four components that comprised genes peaking during different periods of the bloom. Photoautotrophic nitrogen-fixing Cyanobacteria displayed the highest connectivity among the microbes, in contrast to chemoautotrophic ammonia-oxidizing Thaumarchaeota, while heterotrophs dominated connectivity among pre- and post-bloom peaking genes. The network was also composed of distinct functional connectivities, with an early season balance between carbon metabolism and ATP synthesis shifting to a dominance of ATP synthesis during the bloom, while carbon degradation, specifically through the glyoxylate shunt, characterized the post-bloom period, driven by Alphaproteobacteria as well as by Gammaproteobacteria of the SAR86 and SAR92 clusters. Our study stresses the exceptionally strong biotic driving force executed by cyanobacterial blooms on associated microbial communities in the Baltic Sea and highlights the impact cyanobacterial blooms have on functional microbial community composition.

  12. Impact of multispecies diatom bloom on plankton community structure in Sundarban mangrove wetland, India

    International Nuclear Information System (INIS)

    Biswas, Sejuti Naha; Rakshit, Dibyendu; Sarkar, Santosh Kumar; Sarangi, Ranjit Kumar; Satpathy, Kamala Kanta

    2014-01-01

    Highlights: • A multispecies algal bloom was studied in coastal regions of Sundarban wetland. • Sharp changes in plankton community structure and hydrological parameters observed. • Chlorophyll a showed highest cell density (11.4 × 10 5 cells l −1 ) during bloom phase. • MODIS Aqua derived chlorophyll maps have been interpreted. - Abstract: A multispecies bloom caused by the centric diatoms, viz. Coscinodiscus radiatus, Chaetoceros lorenzianus and the pennate diatom Thalassiothrix frauenfeldii was investigated in the context of its impact on phytoplankton and microzooplankton (the loricate ciliate tintinnids) in the coastal regions of Sagar Island, the western part of Sundarban mangrove wetland, India. Both number (15–18 species) and cell densities (12.3 × 10 3 cells l −1 to 11.4 × 10 5 cells l −1 ) of phytoplankton species increased during peak bloom phase, exhibiting moderately high species diversity (H′ = 2.86), richness (R′ = 6.38) and evenness (E′ = 0.80). The diatom bloom, which existed for a week, had a negative impact on the tintinnid community in terms of drastic changes in species diversity index (1.09–0.004) and population density (582.5 × 10 3 to 50 × 10 3 ind m −3 ). The bloom is suggested to have been driven by the aquaculture activities and river effluents resulting high nutrient concentrations in this region. An attempt has been made to correlate the satellite remote sensing-derived information to the bloom conditions. MODIS-Aqua derived chlorophyll maps have been interpreted

  13. Using multispectral imaging flow cytometry to assess an in vitro intracellular Burkholderia thailandensis infection model.

    Science.gov (United States)

    Jenner, Dominic; Ducker, Catherine; Clark, Graeme; Prior, Jo; Rowland, Caroline A

    2016-04-01

    The use of in vitro models to understand the interaction of bacteria with host cells is well established. In vitro bacterial infection models are often used to quantify intracellular bacterial load by lysing cell populations and subsequently enumerating the bacteria. Modern established techniques employ the use of fluorescence technologies such as flow cytometry, fluorescent microscopy, and/or confocal microscopy. However, these techniques often lack either the quantification of large data sets (microscopy) or use of gross fluorescence signal which lacks the visual confirmation that can provide additional confidence in data sets. Multispectral imaging flow cytometry (MIFC) is a novel emerging field of technology. This technology captures a bright field and fluorescence image of cells in a flow using a charged coupled device camera. It allows the analysis of tens of thousands of single cell images, making it an extremely powerful technology. Here MIFC was used as an alternative method of analyzing intracellular bacterial infection using Burkholderia thailandensis E555 as a model organism. It has been demonstrated that the data produced using traditional enumeration is comparable to data analyzed using MIFC. It has also been shown that by using MIFC it is possible to generate other data on the dynamics of the infection model rather than viable counts alone. It has been demonstrated that it is possible to inhibit the uptake of bacteria into mammalian cells and identify differences between treated and untreated cell populations. The authors believe this to be the first use of MIFC to analyze a Burkholderia bacterial species during intracellular infection. © 2016 Crown copyright. Published by Wiley Periodicals Inc. on behalf of ISAC. © 2015 International Society for Advancement of Cytometry.

  14. Sensing the enemy within: how macrophages detect intracellular Gram-negative bacteria.

    Science.gov (United States)

    Demon, Dieter; Vande Walle, Lieselotte; Lamkanfi, Mohamed

    2014-12-01

    Caspase-11 contributes to host defense against Gram-negative bacterial pathogens by inducing an inflammatory form of programmed cell death in infected cells. Lipopolysaccharides (LPS) have been identified as the microbial agents that stimulate caspase-11 activation; however, the mechanism of LPS detection has been unknown. In a recent study, Shao and colleagues demonstrate that caspase-11 and its human homologues, caspases -4 and -5, unexpectedly act as direct sensors of cytosolic LPS. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  15. Sensing the enemy within: how macrophages detect intracellular Gram-negative bacteria

    OpenAIRE

    Demon, Dieter; Vande Walle, Lieselotte; Lamkanfi, Mohamed

    2014-01-01

    Caspase-11 contributes to host defense against Gram-negative bacterial pathogens by inducing an inflammatory form of programmed cell death in infected cells. Lipopolysaccharides (LPS) have been identified as the microbial agents that stimulate caspase-11 activation; however, the mechanism of LPS detection has been unknown. In a recent study, Shao and colleagues demonstrate that caspase-11 and its human homologues, caspases -4 and -5, unexpectedly act as direct sensors of cytosolic LPS.

  16. Pathoadaptation of the Intracellular Bacteria Shigella and Chlamydia: Virulence, Antivirulence, and Tissue Tropism

    Science.gov (United States)

    2015-04-27

    associated with shigellosis (otherwise known as bacillary dysentery) include diarrhea, sometimes bloody; fever; stomach cramps; and tenesmus. Possible...host defenses, such as the acidic environment of the stomach , the competing commensal microbiota of the gastrointestinal tract, and the nearly...but are associated with more severe, invasive disease, and can result in complications such as genital ulcers and proctitis (331). Although six

  17. Use of magnetic nanobeads to study intracellular antigen processing

    Energy Technology Data Exchange (ETDEWEB)

    Perrin-Cocon, Laure A.; Chesne, Serge; Pignot-Paintrand, Isabelle; Marche, Patrice N.; Villiers, Christian L. E-mail: christian.villiers@cea.fr

    2001-07-01

    Magnetic nanobeads were covalently linked to antigens and used as a tool to simultaneously follow their intracellular transport into the cells and specifically purify the intracellular compartments implicated in antigen processing. The protein content of these vesicles was analysed by 2D-electrophoresis. Furthermore, nanobeads allowed intracellular localisation of the antigen in electron and fluorescence microscopy.

  18. Use of magnetic nanobeads to study intracellular antigen processing

    International Nuclear Information System (INIS)

    Perrin-Cocon, Laure A.; Chesne, Serge; Pignot-Paintrand, Isabelle; Marche, Patrice N.; Villiers, Christian L.

    2001-01-01

    Magnetic nanobeads were covalently linked to antigens and used as a tool to simultaneously follow their intracellular transport into the cells and specifically purify the intracellular compartments implicated in antigen processing. The protein content of these vesicles was analysed by 2D-electrophoresis. Furthermore, nanobeads allowed intracellular localisation of the antigen in electron and fluorescence microscopy

  19. Analysis of algal bloom risk with uncertainties in lakes by integrating self-organizing map and fuzzy information theory.

    Science.gov (United States)

    Chen, Qiuwen; Rui, Han; Li, Weifeng; Zhang, Yanhui

    2014-06-01

    Algal blooms are a serious problem in waters, which damage aquatic ecosystems and threaten drinking water safety. However, the outbreak mechanism of algal blooms is very complex with great uncertainty, especially for large water bodies where environmental conditions have obvious variation in both space and time. This study developed an innovative method which integrated a self-organizing map (SOM) and fuzzy information diffusion theory to comprehensively analyze algal bloom risks with uncertainties. The Lake Taihu was taken as study case and the long-term (2004-2010) on-site monitoring data were used. The results showed that algal blooms in Taihu Lake were classified into four categories and exhibited obvious spatial-temporal patterns. The lake was mainly characterized by moderate bloom but had high uncertainty, whereas severe blooms with low uncertainty were observed in the northwest part of the lake. The study gives insight on the spatial-temporal dynamics of algal blooms, and should help government and decision-makers outline policies and practices on bloom monitoring and prevention. The developed method provides a promising approach to estimate algal bloom risks under uncertainties. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Arylthiazole antibiotics targeting intracellular methicillin-resistant Staphylococcus aureus (MRSA) that interfere with bacterial cell wall synthesis.

    Science.gov (United States)

    Eid, Islam; Elsebaei, Mohamed M; Mohammad, Haroon; Hagras, Mohamed; Peters, Christine E; Hegazy, Youssef A; Cooper, Bruce; Pogliano, Joe; Pogliano, Kit; Abulkhair, Hamada S; Seleem, Mohamed N; Mayhoub, Abdelrahman S

    2017-10-20

    The promising antibacterial potency of arylthiazole antibiotics is offset by their limited activity against intracellular bacteria (namely methicillin-resistant Staphylococcus aureus (MRSA)), similar to many clinically-approved antibiotics. The failure to target these hidden pathogens is due to the compounds' lack of proper characteristics to accumulate intracellularly. Fine tuning of the size and polar-surface-area of the linking heteroaromatic ring provided a new series of 5-thiazolylarylthiazoles with balanced properties that allow them to sufficiently cross and accumulate inside macrophages infected with MRSA. The most promising compound 4i exhibited rapid bactericidal activity, good metabolic stability and produced over 80% reduction of intracellular MRSA in infected macrophages. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  1. Antibiotics from predatory bacteria

    Directory of Open Access Journals (Sweden)

    Juliane Korp

    2016-03-01

    Full Text Available Bacteria, which prey on other microorganisms, are commonly found in the environment. While some of these organisms act as solitary hunters, others band together in large consortia before they attack their prey. Anecdotal reports suggest that bacteria practicing such a wolfpack strategy utilize antibiotics as predatory weapons. Consistent with this hypothesis, genome sequencing revealed that these micropredators possess impressive capacities for natural product biosynthesis. Here, we will present the results from recent chemical investigations of this bacterial group, compare the biosynthetic potential with that of non-predatory bacteria and discuss the link between predation and secondary metabolism.

  2. Chaos Theory and James Joyce's "ulysses": Leopold Bloom as a Human COMPLEX@SYSTEM^

    Science.gov (United States)

    Mackey, Peter Francis

    1995-01-01

    These four ideas apply as much to our lives as to the life of Leopold Bloom: (1) A trivial decision can wholly change a life. (2) A chance encounter can dramatically alter life's course. (3) A contingent nexus exists between consciousness and environment. (4) A structure of meaning helps us interpret life's chaos. These ideas also relate to a contemporary science called by some "chaos theory." The connection between Ulysses and chaos theory enhances our understanding of Bloom's day; it also suggests that this novel may be about the real process of life itself. The first chapter explains how Joyce's own essays and comments to friends compel attention to the links between Ulysses and chaos theory. His scientific contemporaries anticipated chaos theory, and their ideas seem to have rubbed off on him. We see this in his sense of trivial things and chance, his modernistic organizational impulses, and the contingent nature of Bloom's experience. The second chapter studies what chaos theory and Joyce's ideas tell us about "Ithaca," the episode which particularly implicates our processes of interpreting this text as well as life itself as we face their chaos. The third chapter examines Bloom's close feel for the aboriginal world, a contingency that clarifies his vulnerability to trivial changes. The fourth chapter studies how Bloom's stream of consciousness unfolds--from his chance encounters with trivial things. Beneath this stream's seeming chaos, Bloom's distinct personality endures, similar to how Joyce's schemas give Ulysses an imbedded, underlying order. The fifth chapter examines how trivial perturbations, such as Lyons' misunderstanding about "Throwaway," produce small crises for Bloom, exacerbating his seeming impotence before his lonely "fate.". The final chapter analyzes Bloom's views that fate and chance dictate his life. His views provide an opportunity to explore the implications chaos theory has for our understanding of free will and determinism. Ultimately

  3. Hydrogen production by nonphotosynthetic bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Huang, S.D.; Secor, C.K.; Zweig, R.M.; Ascione, R.

    1984-01-01

    H-producing nonphotosynthetic bacteria are identified and H from sewage treatment plants, H from rumen bacteria, and large-scale production of H through the genetic manipulation of H-producing nonphotosynthetic bacteria are discussed. (Refs. 36).

  4. Harvesting Environmental Microalgal Blooms for Remediation and Resource Recovery: A Laboratory Scale Investigation with Economic and Microbial Community Impact Assessment

    Directory of Open Access Journals (Sweden)

    Jagroop Pandhal

    2017-12-01

    Full Text Available A laboratory based microflotation rig termed efficient FLOtation of Algae Technology (eFLOAT was used to optimise parameters for harvesting microalgal biomass from eutrophic water systems. This was performed for the dual objectives of remediation (nutrient removal and resource recovery. Preliminary experiments demonstrated that chitosan was more efficient than alum for flocculation of biomass and the presence of bacteria could play a positive role and reduce flocculant application rates under the natural conditions tested. Maximum biomass removal from a hyper-eutrophic water retention pond sample was achieved with 5 mg·L−1 chitosan (90% Chlorophyll a removal. Harvesting at maximum rates showed that after 10 days, the bacterial diversity is significantly increased with reduced cyanobacteria, indicating improved ecosystem functioning. The resource potential within the biomass was characterized by 9.02 μg phosphate, 0.36 mg protein, and 103.7 μg lipid per mg of biomass. Fatty acid methyl ester composition was comparable to pure cultures of microalgae, dominated by C16 and C18 chain lengths with saturated, monounsaturated, and polyunsaturated fatty acids. Finally, the laboratory data was translated into a full-size and modular eFLOAT system, with estimated costs as a novel eco-technology for efficient algal bloom harvesting.

  5. Influence of Didymosphenia geminata blooms on prey composition and associated diet and growth of Brown Trout

    Science.gov (United States)

    James, Daniel A.; Chipps, Steven R.

    2016-01-01

    We compared diet, stomach fullness, condition, and growth of Brown Trout Salmo trutta among streams with or without blooms of the benthic diatom Didymosphenia geminata in the Black Hills, South Dakota. In Rapid Creek, where D. geminata blooms covered ∼30% of the stream bottom, Brown Trout consumed fewer ephemeropterans (6–8% by weight) than individuals from two stream sections that have not had D. geminatablooms (Castle and Spearfish creeks; 13–39% by weight). In contrast, dipterans (primarily Chironomidae) represented a larger percentage of Brown Trout diets from Rapid Creek (D. geminata blooms present; 16–28% dry weight) compared with diets of trout from streams without D. geminata blooms (6–19% dry weight). Diets of small Brown Trout (100–199 mm TL) reflected the invertebrate species composition in benthic stream samples; in Rapid Creek, ephemeropterans were less abundant whereas dipterans were more abundant than in streams without D. geminata blooms. Stomach fullness and condition of Brown Trout from Rapid Creek were generally greater than those of Brown Trout from other populations. Linkages among invertebrate availability, diet composition, and condition of Brown Trout support the hypothesis that changes in invertebrate assemblages associated with D. geminata (i.e., more Chironomidae) could be contributing to high recruitment success for small Brown Trout in Rapid Creek.

  6. Use of phosphorus to reduce blooms of the benthic diatom Didymosphenia geminata in an oligotrophic stream

    Science.gov (United States)

    James, Daniel A.; Bothwell, Max L.; Chipps, Steven R.; Carreiro, John

    2015-01-01

    Blooms of the benthic alga, Didymosphenia geminata [Lyngbye (Schmidt)], were first documented in Rapid Creek, South Dakota, in 2002 and have since been associated with changes to aquatic resources. Low concentration of P has been associated with D. geminata stalk development (i.e., blooms), so we considered elevating P as a possible method to reduce D. geminata blooms. We conducted 2 whole-stream P-enrichment experiments in Rapid Creek during 2007 and 2008. Enrichment with a slow-release fertilizer (Osmocote®: 14-14-14) in 2007 significantly reduced D. geminata blooms (indexed by D. geminata biomass) compared to upstream control sites. The reduction in biomass was less pronounced as distance from the enrichment source increased, a result indicating that P augmentation effectively decreased D. geminata biomass. In 2008, we implemented a before-after–control-impact (BACI) study to assess effects of a quick-release fertilizer (MAP: 11-52-0) on D. geminata biomass. The addition of 6 μg/L P to Rapid Creek resulted in a significant decrease in D. geminata biomass within 0.6 km downstream of the nutrient-addition point. Effects on D. geminata biomass were not evident further downstream. This study provides evidence to support the hypothesis that low P concentration regulates D. geminata blooms.

  7. Wintertime Phytoplankton Blooms in the Western Equatorial Indian Ocean Associated With the Madden-Julian Oscillation

    Science.gov (United States)

    Liao, Xiaomei; Du, Yan; Zhan, Haigang; Wang, Tianyu; Feng, Ming

    2017-12-01

    This study investigated boreal wintertime phytoplankton blooms in the western equatorial Indian Ocean (WEIO) and the underlying physical mechanisms. The Sea viewing Wide field of View sensor (SeaWiFS) chlorophyll-a (Chla) concentrations show that phytoplankton blooms occur in the WEIO during December-March. The development of these blooms is not only a seasonal process but also consists of 2-3 intraseasonal events induced by the Madden-Julian Oscillation (MJO). During a typical intraseasonal event, enhanced cross-equatorial wind induces strong upwelling and ocean mixing, thus increasing the supply of nutrients to the surface in equatorial regions. Argo profiles clearly show various responses to the intraseasonal wind bursts, including shoaling of the thermocline and deepening of the mixed layer. Further analysis reveals that the former is the dominant mechanism for the blooms along the equator, while the latter controls the high Chla concentrations off the coast of Somalia. Surface ocean circulations not only account for the blooms south of the equator but also modulate the thermocline depth in the WEIO. The shallower thermocline during the early period of the northeast monsoon season provides favorable conditions for a stronger Chla response to intraseasonal forcing.

  8. Modeling spring-summer phytoplankton bloom in Lake Michigan with and without riverine nutrient loading

    Science.gov (United States)

    Luo, Lin; Wang, Jia; Hunter, Timothy; Wang, Dongxiao; Vanderploeg, Henry A.

    2017-11-01

    There were two phytoplankton blooms captured by remote sensing in Lake Michigan in 1998, one from March to May, and one during June. In this paper, those phytoplankton blooms were simulated by a coupled physical-biological model, driven by observed meteorological forcing in 1998. The model reasonably reproduced the lake currents. The biological model results, with and without riverine nutrient loading, were compared with the remote sensing data. A 3-month-long donut-like phytoplankton bloom that appeared in southern Lake Michigan was reasonably well simulated only when riverine input was included, indicating the importance of riverine nutrient input for supporting the growth of phytoplankton in Lake Michigan. The model with riverine input also captured a second event-driven phytoplankton bloom during June with weaker magnitude that occurred in mid-south Lake Michigan, which lasted for about 20 days. The major reason for the weaker bloom in June was that vertical mixing in the hydrodynamic model was too weak (leading to a mixed-layer depth of 20 m) to bring the bottom nutrient-rich water up to the epilimnion. High chlorophyll concentration that persisted in Green Bay for almost a year was simulated with less intensity.

  9. Temporal influences on satellite retrieval of cyanobacteria bloom: an examination in Lake Taihu, China

    Science.gov (United States)

    Zhang, Yue; Liu, Yuanbo; Ruan, Renzong; Zhao, Dongbo

    2009-10-01

    Satellite imagery provides a cost-effective way to retrieve the cyanbacteria bloom dynamics, which is useful to early warning of the blooms. However, temporal variations in sun-target-satellite geometry and atmosphere may generate inconsistencies in multi-temporal images. To explore to what extent temporal influences could affect the retrieved results, we applied the single band and the band ratio approaches to retrieve cyanobacteria bloom in Lake Taihu of China. We used the Moderate Resolution Imaging Spectroradiometer (MODIS) products in the cases with and without correction for sun-target-satellite geometry and atmospheric effects for the whole year 2006. In addition, we made use of MODIS data including aerosol optical thickness (AOT), solar zenith angle and sensor zenith angle, all of which are indicators of the temporal influences. We then analyzed the relationships of retrieval differences with the three indicators to evaluate the temporal influences quantitatively. Our results showed that both AOT and solar zenith angle had a positive correlation with the retrieval of cyanobacteria bloom. Although it is yet under investigation if this relationship could hold on for other cases, here we emphasized that for reliable monitoring the dynamics of bloom, it should be careful to apply the approaches using satellite data without radiometric correction.

  10. Cyanobacteria of the 2016 Lake Okeechobee and Okeechobee Waterway harmful algal bloom

    Science.gov (United States)

    Rosen, Barry H.; Davis, Timothy W.; Gobler, Christopher J.; Kramer, Benjamin J.; Loftin, Keith A.

    2017-05-31

    The Lake Okeechobee and the Okeechobee Waterway (Lake Okeechobee, the St. Lucie Canal and River, and the Caloosahatchee River) experienced an extensive harmful algal bloom within Lake Okeechobee, the St. Lucie Canal and River and the Caloosahatchee River in 2016. In addition to the very visible bloom of the cyanobacterium Microcystis aeruginosa, several other cyanobacteria were present. These other species were less conspicuous; however, they have the potential to produce a variety of cyanotoxins, including anatoxins, cylindrospermopsins, and saxitoxins, in addition to the microcystins commonly associated with Microcystis. Some of these species were found before, during, and 2 weeks after the large Microcystis bloom and could provide a better understanding of bloom dynamics and succession. This report provides photographic documentation and taxonomic assessment of the cyanobacteria present from Lake Okeechobee and the Caloosahatchee River and St. Lucie Canal, with samples collected June 1st from the Caloosahatchee River and Lake Okeechobee and in July from the St. Lucie Canal. The majority of the images were of live organisms, allowing their natural complement of pigmentation to be captured. The report provides a digital image-based taxonomic record of the Lake Okeechobee and the Okeechobee Waterway microscopic flora. It is anticipated that these images will facilitate current and future studies on this system, such as understanding the timing of cyanobacteria blooms and their potential toxin production.

  11. Dynamics of a Prorocentrum minimum bloom along the northern coast of Sinaloa, Mexico

    Science.gov (United States)

    Martínez-López, Aída; Escobedo-Urías, Diana Cecilia; Ulloa-Pérez, Ana Elsi; Aguirre, Raul

    2008-08-01

    To investigate the relative importance of mesoscale physical events, such as upwellings and physical and chemical variables during an algae bloom of Prorocentrum minimum, 25 sampling sites were established offshore of the Navachiste Lagoon Complex on the east side of the Gulf of California. Samples were analyzed for phytoplankton concentration, water chemistry, and temperature during November 1999, January, March, April, May, and August 2000. Satellite imagery of sea surface temperature (SST) for April 2000 was processed to obtain a synoptic view of the area during the extraordinary bloom of P. minimum in the open waters of the Gulf of California. The bloom was associated with change of oceanographic conditions from moderate winds to calm period, temperature increase and high nitrate (NO 3--N) and ammonia (NH 4+-N) content in the offshore waters. Depletion of these nutrients during the bloom suggests that this species uses both types of nitrogen substrates. Cysts in the northernmost sampling stations in January and March indicate that upwelling water, rich in nitrates, also carried a seed stock population of P. minimum. SST patterns in the satellite imagery suggest wind-forcing as the responsible mechanisms triggering the algal bloom offshore of the Navachiste Lagoon Complex.

  12. Incorporation of Bloom's taxonomy into multiple-choice examination questions for a pharmacotherapeutics course.

    Science.gov (United States)

    Kim, Myo-Kyoung; Patel, Rajul A; Uchizono, James A; Beck, Lynn

    2012-08-10

    To incorporate Bloom's taxonomy into multiple-choice examination questions in a pharmacotherapeutics course and assess its effectiveness in detecting areas of improvement in learning. Bloom's taxonomy was incorporated into examination questions through a multi-step process: Sample questions representing each learning domain within Bloom's taxonomy (knowledge, comprehension, application, analysis, synthesis, and evaluation) were introduced to students during lecture presentations and discussions. Quiz and examination containing questions categorized according to Bloom's taxonomy were administered to students. During review sessions following each quiz or examination, the categorization of each question was provided to students and feedback from students was gathered. The effect of the 5 types of test questions on the correct response fraction and discrimination index was determined after combining synthesis and evaluation. Correct response fractions for knowledge, comprehension, and application questions were significantly higher than those for analysis and synthesis/evaluation questions (plearning assistance, the majority realized the importance of critical-thinking skills in the learning process. Well-designed multiple-choice questions incorporating different learning domains of Bloom's taxonomy may be a potential method of assessing critical-thinking skills in large classes of students.

  13. [Darwin and bacteria].

    Science.gov (United States)

    Ledermann D, Walter

    2009-02-01

    As in 2009 the scientific world celebrates two hundreds years from the birthday of Charles Darwin and one hundred and fifty from the publication of The Origin of Species, an analysis of his complete work is performed, looking for any mention of bacteria. But it seems that the great naturahst never took knowledge about its existence, something rather improbable in a time when the discovery of bacteria shook the medical world, or he deliberately ignored them, not finding a place for such microscopic beings into his theory of evolution. But the bacteria badly affected his familiar life, killing scarlet fever one of his children and worsening to death the evolution of tuberculosis of his favourite Annie. Darwin himself could suffer the sickness of Chagas, whose etiological agent has a similar level to bacteria in the scale of evolution.

  14. Extracellular communication in bacteria

    DEFF Research Database (Denmark)

    Chhabra, S.R.; Philipp, B.; Eberl, L.

    2005-01-01

    molecules, in different Gram-positive and Gram-negative bacteria they control pathogenicity, secondary metabolite production, biofilm differentiation, DNA transfer and bioluminescence. The development of biosensors for the detection of these signal molecules has greatly facilitated their subsequent chemical...

  15. Cytoskeletal Network Morphology Regulates Intracellular Transport Dynamics

    Science.gov (United States)

    Ando, David; Korabel, Nickolay; Huang, Kerwyn Casey; Gopinathan, Ajay

    2015-01-01

    Intracellular transport is essential for maintaining proper cellular function in most eukaryotic cells, with perturbations in active transport resulting in several types of disease. Efficient delivery of critical cargos to specific locations is accomplished through a combination of passive diffusion and active transport by molecular motors that ballistically move along a network of cytoskeletal filaments. Although motor-based transport is known to be necessary to overcome cytoplasmic crowding and the limited range of diffusion within reasonable timescales, the topological features of the cytoskeletal network that regulate transport efficiency and robustness have not been established. Using a continuum diffusion model, we observed that the time required for cellular transport was minimized when the network was localized near the nucleus. In simulations that explicitly incorporated network spatial architectures, total filament mass was the primary driver of network transit times. However, filament traps that redirect cargo back to the nucleus caused large variations in network transport. Filament polarity was more important than filament orientation in reducing average transit times, and transport properties were optimized in networks with intermediate motor on and off rates. Our results provide important insights into the functional constraints on intracellular transport under which cells have evolved cytoskeletal structures, and have potential applications for enhancing reactions in biomimetic systems through rational transport network design. PMID:26488648

  16. Cytoskeletal Network Morphology Regulates Intracellular Transport Dynamics.

    Science.gov (United States)

    Ando, David; Korabel, Nickolay; Huang, Kerwyn Casey; Gopinathan, Ajay

    2015-10-20

    Intracellular transport is essential for maintaining proper cellular function in most eukaryotic cells, with perturbations in active transport resulting in several types of disease. Efficient delivery of critical cargos to specific locations is accomplished through a combination of passive diffusion and active transport by molecular motors that ballistically move along a network of cytoskeletal filaments. Although motor-based transport is known to be necessary to overcome cytoplasmic crowding and the limited range of diffusion within reasonable timescales, the topological features of the cytoskeletal network that regulate transport efficiency and robustness have not been established. Using a continuum diffusion model, we observed that the time required for cellular transport was minimized when the network was localized near the nucleus. In simulations that explicitly incorporated network spatial architectures, total filament mass was the primary driver of network transit times. However, filament traps that redirect cargo back to the nucleus caused large variations in network transport. Filament polarity was more important than filament orientation in reducing average transit times, and transport properties were optimized in networks with intermediate motor on and off rates. Our results provide important insights into the functional constraints on intracellular transport under which cells have evolved cytoskeletal structures, and have potential applications for enhancing reactions in biomimetic systems through rational transport network design. Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  17. Intracellular accumulation of norfloxacin in Mycobacterium smegmatis.

    Science.gov (United States)

    Corti, S; Chevalier, J; Cremieux, A

    1995-01-01

    To evaluate the intracellular accumulation of norfloxacin in mycobacteria, two methods were used with Mycobacterium smegmatis. A radiometric method (K. V. Cundy, C. E. Fasching, K. E. Willard, and L. R. Peterson, J. Antimicrob. Chemother. 28:491-497, 1991) was used without great modification, but the fluorometric method (P. G. S. Mortimer and L. J. V. Piddock, J. Antimicrob. Chemother. 28:639-653, 1991) was changed considerably. Indeed, adsorption of the quinolone to the bacterial surface was characterized by measuring the level of accumulation of 0 degree C. Taking into account the adsorption, the pH of the washing buffer was increased from 7.0 to 9.0 to improve the desorption of norfloxacin from the cell surface. Both the fluorometric method, with the technical improvement, and the radiometric method could be used to estimate the intracellular accumulation of norfloxacin, which resulted from the difference between the whole uptake measured at 37 degrees C and the adsorption measured at 0 degrees C. A total of 35 ng of norfloxacin per mg of cells (dry weight) penetrated into the M. smegmatis cell, and the steady state was achieved in 5 min. Use of inhibitors of the proton motive force revealed that transport of norfloxacin was energy independent. Thus, the same mechanisms of quinolone accumulation that occur in eubacteria seem to occur in mycobacteria, at least in M. smegmatis. PMID:8585727

  18. Fluorescent nanoparticles for intracellular sensing: a review.

    Science.gov (United States)

    Ruedas-Rama, Maria J; Walters, Jamie D; Orte, Angel; Hall, Elizabeth A H

    2012-11-02

    Fluorescent nanoparticles (NPs), including semiconductor NPs (Quantum Dots), metal NPs, silica NPs, polymer NPs, etc., have been a major focus of research and development during the past decade. The fluorescent nanoparticles show unique chemical and optical properties, such as brighter fluorescence, higher photostability and higher biocompatibility, compared to classical fluorescent organic dyes. Moreover, the nanoparticles can also act as multivalent scaffolds for the realization of supramolecular assemblies, since their high surface to volume ratio allow distinct spatial domains to be functionalized, which can provide a versatile synthetic platform for the implementation of different sensing schemes. Their excellent properties make them one of the most useful tools that chemistry has supplied to biomedical research, enabling the intracellular monitoring of many different species for medical and biological purposes. In this review, we focus on the developments and analytical applications of fluorescent nanoparticles in chemical and biological sensing within the intracellular environment. The review also points out the great potential of fluorescent NPs for fluorescence lifetime imaging microscopy (FLIM). Finally, we also give an overview of the current methods for delivering of fluorescent NPs into cells, where critically examine the benefits and liabilities of each strategy. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. [Intracellular signaling mechanisms in thyroid cancer].

    Science.gov (United States)

    Mondragón-Terán, Paul; López-Hernández, Luz Berenice; Gutiérrez-Salinas, José; Suárez-Cuenca, Juan Antonio; Luna-Ceballos, Rosa Isela; Erazo Valle-Solís, Aura

    2016-01-01

    Thyroid cancer is the most common malignancy of the endocrine system, the papillary variant accounts for 80-90% of all diagnosed cases. In the development of papillary thyroid cancer, BRAF and RAS genes are mainly affected, resulting in a modification of the system of intracellular signaling proteins known as «protein kinase mitogen-activated» (MAPK) which consist of «modules» of internal signaling proteins (Receptor/Ras/Raf/MEK/ERK) from the cell membrane to the nucleus. In thyroid cancer, these signanling proteins regulate diverse cellular processes such as differentiation, growth, development and apoptosis. MAPK play an important role in the pathogenesis of thyroid cancer as they are used as molecular biomarkers for diagnostic, prognostic and as possible therapeutic molecular targets. Mutations in BRAF gene have been correlated with poor response to treatment with traditional chemotherapy and as an indicator of poor prognosis. To review the molecular mechanisms involved in intracellular signaling of BRAF and RAS genes in thyroid cancer. Molecular therapy research is in progress for this type of cancer as new molecules have been developed in order to inhibit any of the components of the signaling pathway (RET/PTC)/Ras/Raf/MEK/ERK; with special emphasis on the (RET/PTC)/Ras/Raf section, which is a major effector of ERK pathway. Copyright © 2016 Academia Mexicana de Cirugía A.C. Publicado por Masson Doyma México S.A. All rights reserved.

  20. Stochastic models of intracellular calcium signals

    Energy Technology Data Exchange (ETDEWEB)

    Rüdiger, Sten, E-mail: sten.ruediger@physik.hu-berlin.de

    2014-01-10

    Cellular signaling operates in a noisy environment shaped by low molecular concentrations and cellular heterogeneity. For calcium release through intracellular channels–one of the most important cellular signaling mechanisms–feedback by liberated calcium endows fluctuations with critical functions in signal generation and formation. In this review it is first described, under which general conditions the environment makes stochasticity relevant, and which conditions allow approximating or deterministic equations. This analysis provides a framework, in which one can deduce an efficient hybrid description combining stochastic and deterministic evolution laws. Within the hybrid approach, Markov chains model gating of channels, while the concentrations of calcium and calcium binding molecules (buffers) are described by reaction–diffusion equations. The article further focuses on the spatial representation of subcellular calcium domains related to intracellular calcium channels. It presents analysis for single channels and clusters of channels and reviews the effects of buffers on the calcium release. For clustered channels, we discuss the application and validity of coarse-graining as well as approaches based on continuous gating variables (Fokker–Planck and chemical Langevin equations). Comparison with recent experiments substantiates the stochastic and spatial approach, identifies minimal requirements for a realistic modeling, and facilitates an understanding of collective channel behavior. At the end of the review, implications of stochastic and local modeling for the generation and properties of cell-wide release and the integration of calcium dynamics into cellular signaling models are discussed.

  1. The effect of environmental parameters and cyanobacterial blooms on phytoplankton dynamics of a Portuguese temperate lake

    DEFF Research Database (Denmark)

    De Figueiredo, Daniela R.; P. S. Reboleira, Ana Sofia; Antunes, Sara C.

    2006-01-01

    The increasing occurrence of cyanobacterial blooms in freshwaters is of great concern due to the ability of many cyanobacteria to produce cyanotoxins. In the present work, the eutrophied Vela Lake (Central Portugal), used for recreational purposes and as a water source for agriculture...... (particularly phosphorus). Diatoms were dominant during winter months (inferior temperatures and higher nutrients availability) followed by green algae in early spring and then cyanobacteria from late spring until early autumn (less nutrient availability and higher temperatures). A massive cyanobacterial bloom...... for the phytoplanktonic assemblage during the study period was increased in about 7% achieving a total of 61.0%, indicating a correlation that may be due to the known competitive advantage and/or allelopathy of the bloom-forming cyanobacteria towards microalgae....

  2. Categorization of ber varieties in relation to blooming period, fruit setting and harvesting time

    International Nuclear Information System (INIS)

    Sharif, N.; Abbas, M.M.; Ishfaq, M.; Memon, N.U.N.

    2013-01-01

    Thirty four local Ber varieties were evaluated at Horticultural Research Institute AARI, Faisalabad, Horticultural Research Station Bahawalpur (Punjab) and Jujube Research Station, Tandojam (Sindh). Traits viz. total period of blooming (dates), peak period of blooming (dates), total period of fruit set (dates), peak period of fruit set (dates), total period of fruit harvest (dates), peak period of fruit harvest (dates), total flowering days, peak flowering days, total fruit setting days, peak fruit setting days, total harvesting days and peak harvesting days were studied. The results revealed significant differences in parameters studied except total period of blooming under Tandojam, Sindh conditions. Varieties were classified as early, mid and late season for both provinces. Local varieties had potential for further manipulation in terms of variety improvement to attract growers for extensive ber cultivations under changing global climatic scenario. (author)

  3. Loss of RMI2 Increases Genome Instability and Causes a Bloom-Like Syndrome.

    Directory of Open Access Journals (Sweden)

    Damien F Hudson

    2016-12-01

    Full Text Available Bloom syndrome is a recessive human genetic disorder with features of genome instability, growth deficiency and predisposition to cancer. The only known causative gene is the BLM helicase that is a member of a protein complex along with topoisomerase III alpha, RMI1 and 2, which maintains replication fork stability and dissolves double Holliday junctions to prevent genome instability. Here we report the identification of a second gene, RMI2, that is deleted in affected siblings with Bloom-like features. Cells from homozygous individuals exhibit elevated rates of sister chromatid exchange, anaphase DNA bridges and micronuclei. Similar genome and chromosome instability phenotypes are observed in independently derived RMI2 knockout cells. In both patient and knockout cell lines reduced localisation of BLM to ultra fine DNA bridges and FANCD2 at foci linking bridges are observed. Overall, loss of RMI2 produces a partially active BLM complex with mild features of Bloom syndrome.

  4. Maintenance of coastal surface blooms by surface temperature stratification and wind drift.

    Directory of Open Access Journals (Sweden)

    Mary Carmen Ruiz-de la Torre

    Full Text Available Algae blooms are an increasingly recurrent phenomenon of potentially socio-economic impact in coastal waters globally and in the coastal upwelling region off northern Baja California, Mexico. In coastal upwelling areas the diurnal wind pattern is directed towards the coast during the day. We regularly found positive Near Surface Temperature Stratification (NSTS, the resulting density stratification is expected to reduce the frictional coupling of the surface layer from deeper waters and allow for its more efficient wind transport. We propose that the net transport of the top layer of approximately 2.7 kilometers per day towards the coast helps maintain surface blooms of slow growing dinoflagellate such as Lingulodinium polyedrum. We measured: near surface stratification with a free-rising CTD profiler, trajectories of drifter buoys with attached thermographs, wind speed and direction, velocity profiles via an Acoustic Doppler Current Profiler, Chlorophyll and cell concentration from water samples and vertical migration using sediment traps. The ADCP and drifter data agree and show noticeable current shear within the first meters of the surface where temperature stratification and high cell densities of L. polyedrum were found during the day. Drifters with 1m depth drogue moved towards the shore, whereas drifters at 3 and 5 m depth showed trajectories parallel or away from shore. A small part of the surface population migrated down to the sea floor during night thus reducing horizontal dispersion. The persistent transport of the surface bloom population towards shore should help maintain the bloom in favorable environmental conditions with high nutrients, but also increasing the potential socioeconomic impact of the blooms. The coast wise transport is not limited to blooms but includes all dissolved and particulate constituents in surface waters.

  5. Occurrence of toxin-producing cyanobacteria blooms in a Brazilian semiarid reservoir

    Directory of Open Access Journals (Sweden)

    I. A. S. Costa

    Full Text Available We report the occurrence of cyanobacterial blooms and the presence of cyanotoxins in water samples from the Armando Ribeiro Gonçalves reservoir (06° 08’ S and 37° 07’ W, located in the state of Rio Grande do Norte, in the semiarid region of northeastern Brazil. The cyanobacterial species were identified and quantified during the rainy and dry seasons in the year 2000. Cyanotoxins such as microcystins, saxitoxins and cylindrospermopsins were analyzed and quantified using HPLC and ELISA methods. The mixed toxic blooms of Cylindrospermopsis raciborskii, Microcystis spp (M. panniformis, M. protocystis, M. novacekii and Aphanizomenon spp (Aphanizomenon gracile, A. cf. manguinii, A. cf. issastschenkoi were persistent and represented 90-100% of the total phytoplankton species. Toxic cyanobacterial blooms from the Armando Ribeiro Gonçalves reservoir were analyzed and found to have three phases in relation to the annual cycle. During the rainy season, an intense toxic bloom of Cylindrospermopsis raciborskii was recorded along with saxitoxins (3.14 µg.L-1. During the transition period, between the rainy and dry seasons, different species of Microscytis occurred and microcystin as high as 8.8 µg.L-1 was recorded. In the dry season, co-dominance of Cylindrospermopsis raciborskii, Microcystis spp and Aphanizomenon spp occurred and the concentrations of saxitoxin remained very low. Our results indicate the presence of microcystins (8.8 µg.L-1 and saxitoxins (3.14 µg.L-1 into the crude water, with increasing concentrations from the second fortnight of April to late May 2000. The occurrence of toxic blooms in this reservoir points to a permanent risk of cyanotoxins in supply waters, indicating the need for the implementation of bloom control measures to improve the water quality. Exposure of the local population to cyanotoxins through their potential accumulation in fish muscle must also be considered.

  6. Eco-evolutionary feedbacks between private and public goods: evidence from toxic algal blooms.

    Science.gov (United States)

    Driscoll, William W; Hackett, Jeremiah D; Ferrière, Régis

    2016-01-01

    The importance of 'eco-evolutionary feedbacks' in natural systems is currently unclear. Here, we advance a general hypothesis for a particular class of eco-evolutionary feedbacks with potentially large, long-lasting impacts in complex ecosystems. These eco-evolutionary feedbacks involve traits that mediate important interactions with abiotic and biotic features of the environment and a self-driven reversal of selection as the ecological impact of the trait varies between private (small scale) and public (large scale). Toxic algal blooms may involve such eco-evolutionary feedbacks due to the emergence of public goods. We review evidence that toxin production by microalgae may yield 'privatised' benefits for individual cells or colonies under pre- and early-bloom conditions; however, the large-scale, ecosystem-level effects of toxicity associated with bloom states yield benefits that are necessarily 'public'. Theory predicts that the replacement of private with public goods may reverse selection for toxicity in the absence of higher level selection. Indeed, blooms often harbor significant genetic and functional diversity: bloom populations may undergo genetic differentiation over a scale of days, and even genetically similar lineages may vary widely in toxic potential. Intriguingly, these observations find parallels in terrestrial communities, suggesting that toxic blooms may serve as useful models for eco-evolutionary dynamics in nature. Eco-evolutionary feedbacks involving the emergence of a public good may shed new light on the potential for interactions between ecology and evolution to influence the structure and function of entire ecosystems. © 2015 John Wiley & Sons Ltd/CNRS.

  7. Site fidelity by bees drives pollination facilitation in sequentially blooming plant species.

    Science.gov (United States)

    Ogilvie, Jane E; Thomson, James D

    2016-06-01

    Plant species can influence the pollination and reproductive success of coflowering neighbors that share pollinators. Because some individual pollinators habitually forage in particular areas, it is also possible that plant species could influence the pollination of neighbors that bloom later. When flowers of a preferred forage plant decline in an area, site-fidelity may cause individual flower feeders to stay in an area and switch plant species rather than search for preferred plants in a new location. A newly blooming plant species may quickly inherit a set of visitors from a prior plant species, and therefore experience higher pollination success than it would in an area where the first species never bloomed. To test this, we manipulated the placement and timing of two plant species, Delphinium barbeyi and later-blooming Gentiana parryi. We recorded the responses of individually marked bumble bee pollinators. About 63% of marked individuals returned repeatedly to the same areas to forage on Delphinium. When Delphinium was experimentally taken out of bloom, most of those site-faithful individuals (78%) stayed and switched to Gentiana. Consequently, Gentiana flowers received more visits in areas where Delphinium had previously flowered, compared to areas where Delphinium was still flowering or never occurred. Gentiana stigmas received more pollen in areas where Delphinium disappeared than where it never bloomed, indicating that Delphinium increases the pollination of Gentiana when they are separated in time. Overall, we show that individual bumble bees are often site-faithful, causing one plant species to increase the pollination of another even when separated in time, which is a novel mechanism of pollination facilitation.

  8. Satellite chlorophyll-a annual bloom characterization in Northeast Brazil, western tropical Atlantic

    Science.gov (United States)

    Kampel, Milton; Rudorff, Natalia M.; Dall Cortivo, Fabio; Freitas, Lucas B.; Valerio, Larissa P.

    2014-11-01

    Time series of satellite-derived sea surface chlorophyll concentration (SSC) from 2002 to 2012 were used to investigate the phenology of phytoplankton bloom in the Sergipe-Alagoas Basin, located in Northeast Brazil, Western Tropical Atlantic. The seasonal phytoplankton cycle is the dominant mode of temporal variability. The use of a Gaussian function to fit the temporal variability of SSC allowed the characterization of the timing and magnitude of the annual phytoplankton bloom in the slope and continental shelf areas. Modeled SSC showed a few differences in relation to mean MODIS-derived temporal curves. The maximum error was 0.14 mg.m-3 in September on the shelf and 0.006 mg.m- 3 in February on the slope. In both areas, SSC data showed that the maximum surface bloom occurs in June, having initiated in March. This cycle is typical of tropical waters of low latitudes where bloom is initiated at lower vertical stability of the water column allowing nutrients from deeper layers to fertilize usually poor and warm waters of the mixed layer. High rainfall increases the continental drainage into the shelf in autumn-winter, which may affect the timing of bloom. However, the flow regulation of the most important river in the region (Sao Francisco River) decreases the potential impact of river inflow in the coastal region. As the shelf and slope showed very similar patterns, it is likely that the processes of wind mixing and water heating/cooling are the most determining factors for the annual cycle of phytoplankton bloom in this region.

  9. Comparative Analysis of Flower Volatiles from Nine Citrus at Three Blooming Stages

    Directory of Open Access Journals (Sweden)

    Muhammad Azam

    2013-11-01

    Full Text Available Volatiles from flowers at three blooming stages of nine citrus cultivars were analyzed by headspace-solid phase microextraction (HS-SPME-GC-MS. Up to 110 volatiles were detected, with 42 tentatively identified from citrus flowers for the first time. Highest amounts of volatiles were present in fully opened flowers of most citrus, except for pomelos. All cultivars were characterized by a high percentage of either oxygenated monoterpenes or monoterpene hydrocarbons, and the presence of a high percentage of nitrogen containing compounds was also observed. Flower volatiles varied qualitatively and quantitatively among citrus types during blooming. Limonene was the most abundant flower volatile only in citrons; α-citral and β-citral ranked 2nd and 3rd only for Bergamot, and unopened flowers of Ponkan had a higher amount of linalool and β-pinene while much lower amount of γ-terpinene and p-cymene than Satsuma. Taking the average of all cultivars, linalool and limonene were the top two volatiles for all blooming stages; β-pinene ranked 3rd in unopened flowers, while indole ranked 3rd for half opened and fully opened flower volatiles. As flowers bloomed, methyl anthranilate increased while 2-hexenal and p-cymene decreased. In some cases, a volatile could be high in both unopened and fully opened flowers but low in half opened ones. Through multivariate analysis, the nine citrus cultivars were clustered into three groups, consistent with the three true citrus types. Furthermore, an influence of blooming stages on clustering was observed, especially with hybrids Satsuma and Huyou. Altogether, it was suggested that flower volatiles can be suitable markers for revealing the genetic relationships between citrus cultivars but the same blooming stage needs to be strictly controlled.

  10. An association network analysis among microeukaryotes and bacterioplankton reveals algal bloom dynamics.

    Science.gov (United States)

    Tan, Shangjin; Zhou, Jin; Zhu, Xiaoshan; Yu, Shichen; Zhan, Wugen; Wang, Bo; Cai, Zhonghua

    2015-02-01

    Algal blooms are a worldwide phenomenon and the biological interactions that underlie their regulation are only just beginning to be understood. It is established that algal microorganisms associate with many other ubiquitous, oceanic organisms, but the interactions that lead to the dynamics of bloom formation are currently unknown. To address this gap, we used network approaches to investigate the association patterns among microeukaryotes and bacterioplankton in response to a natural Scrippsiella trochoidea bloom. This is the first study to apply network approaches to bloom dynamics. To this end, terminal restriction fragment (T-RF) length polymorphism analysis showed dramatic changes in community compositions of microeukaryotes and bacterioplankton over the blooming period. A variance ratio test revealed significant positive overall associations both within and between microeukaryotic and bacterioplankton communities. An association network generated from significant correlations between T-RFs revealed that S. trochoidea had few connections to other microeukaryotes and bacterioplankton and was placed on the edge. This lack of connectivity allowed for the S. trochoidea sub-network to break off from the overall network. These results allowed us to propose a conceptual model for explaining how changes in microbial associations regulate the dynamics of an algal bloom. In addition, key T-RFs were screened by principal components analysis, correlation coefficients, and network analysis. Dominant T-RFs were then identified through 18S and 16S rRNA gene clone libraries. Results showed that microeukaryotes clustered predominantly with Dinophyceae and Perkinsea while the majority of bacterioplankton identified were Alphaproteobacteria, Gammaproteobacteria, and Bacteroidetes. The ecologi-cal roles of both were discussed in the context of these findings. © 2014 Phycological Society of America.

  11. Decadal-Scale Changes of Dinoflagellates and Diatoms in the Anomalous Baltic Sea Spring Bloom

    Science.gov (United States)

    Klais, Riina; Tamminen, Timo; Kremp, Anke; Spilling, Kristian; Olli, Kalle

    2011-01-01

    The algal spring bloom in the Baltic Sea represents an anomaly from the winter-spring bloom patterns worldwide in terms of frequent and recurring dominance of dinoflagellates over diatoms. Analysis of approximately 3500 spring bloom samples from the Baltic Sea monitoring programs revealed (i) that within the major basins the proportion of dinoflagellates varied from 0.1 (Kattegat) to >0.8 (central Baltic Proper), and (ii) substantial shifts (e.g. from 0.2 to 0.6 in the Gulf of Finland) in the dinoflagellate proportion over four decades. During a recent decade (1995–2004) the proportion of dinoflagellates increased relative to diatoms mostly in the northernmost basins (Gulf of Bothnia, from 0.1 to 0.4) and in the Gulf of Finland, (0.4 to 0.6) which are typically ice-covered areas. We hypothesize that in coastal areas a specific sequence of seasonal events, involving wintertime mixing and resuspension of benthic cysts, followed by proliferation in stratified thin layers under melting ice, favors successful seeding and accumulation of dense dinoflagellate populations over diatoms. This head-start of dinoflagellates by the onset of the spring bloom is decisive for successful competition with the faster growing diatoms. Massive cyst formation and spreading of cyst beds fuel the expanding and ever larger dinoflagellate blooms in the relatively shallow coastal waters. Shifts in the dominant spring bloom algal groups can have significant effects on major elemental fluxes and functioning of the Baltic Sea ecosystem, but also in the vast shelves and estuaries at high latitudes, where ice-associated cold-water dinoflagellates successfully compete with diatoms. PMID:21747911

  12. Multiscale bloom dynamics from a high frequency autonomous measurement system in the Eastern English Channel

    Science.gov (United States)

    Derot, Jonathan; Schmitt, François; Gentilhomme, Valérie

    2014-05-01

    We consider here a dataset from an Eulerian automated system, located on the coastal area of the French side of the English Channel (Boulogne-sur-Mer), called MAREL Carnot, operated by IFREMER (France). This system records more than 15 physico-chemical parameters at 20 minutes intervals, and at the constant depth of -1,5m whatever the tidal range. Our study focuses on the period 2004 to 2011. The objective of this study is to have a better understanding of the bloom fluorescence multiscale dynamics, as regards the coastal area of English Channel and possible influence of temperature on this dynamics. Annual blooms are visible, superposed to multiscale fluctuations. The probability density function (PDF) of the fluorescence time series very nicely obeys a power law with slope -2. The PDF for annual portions obeys also power laws, with slopes which are related to the annual average. Empirical mode decomposition (EMD) is used to study the dynamics and display the power spectrum, which will be linked with these dynamics. EMD method is also used to extract a trend and isolate the blooms from the high frequency dynamics. We show that the high frequency part of the fluorescence dynamics has a very large variance during bloom events, compared to normal conditions. We also show that there is a link between the mean winter temperature and the strength of bloom next spring. These results contribute to statistically characterize the bloom dynamics and extract some possible universal relations. Keywords: English Channel; Autonomous monitoring; Power spectra; EMD method; Probability density functions; Power laws.

  13. Bacteria as vectors for gene therapy of cancer.

    LENUS (Irish Health Repository)

    Baban, Chwanrow K

    2012-01-31

    Anti-cancer therapy faces major challenges, particularly in terms of specificity of treatment. The ideal therapy would eradicate tumor cells selectively with minimum side effects on normal tissue. Gene or cell therapies have emerged as realistic prospects for the treatment of cancer, and involve the delivery of genetic information to a tumor to facilitate the production of therapeutic proteins. However, there is still much to be done before an efficient and safe gene medicine is achieved, primarily developing the means of targeting genes to tumors safely and efficiently. An emerging family of vectors involves bacteria of various genera. It has been shown that bacteria are naturally capable of homing to tumors when systemically administered resulting in high levels of replication locally. Furthermore, invasive species can deliver heterologous genes intra-cellularly for tumor cell expression. Here, we review the use of bacteria as vehicles for gene therapy of cancer, detailing the mechanisms of action and successes at preclinical and clinical levels.

  14. Intracellular signaling by diffusion: can waves of hydrogen peroxide transmit intracellular information in plant cells?

    DEFF Research Database (Denmark)

    Vestergaard, Christian L.; Flyvbjerg, Henrik; Møller, Ian Max

    2012-01-01

    Amplitude- and frequency-modulated waves of Ca(2+) ions transmit information inside cells. Reactive Oxygen Species (ROS), specifically hydrogen peroxide, have been proposed to have a similar role in plant cells. We consider the feasibility of such an intracellular communication system in view...

  15. Key role of organic complexation of iron in sustaining phytoplankton blooms in the Pine Island and Amundsen Polynyas (Southern Ocean)

    NARCIS (Netherlands)

    Thuroczy, Charles-Edouard; Alderkamp, Anne-Carlijn; Laan, Patrick; Gerringa, Loes J. A.; Mills, Matthew M.; Van Dijken, Gert L.; De Baar, Hein J. W.; Arrigo, Kevin R.

    2012-01-01

    Primary productivity in the Amundsen Sea (Southern Ocean) is among the highest in Antarctica. The summer phytoplankton bloom in 2009 lasted for > 70 days in both the Pine Island and Amundsen Polynyas. Such productive blooms require a large supply of nutrients, including the trace metal iron (Fe).

  16. The Analysis of Learning Objectives in Iranian Junior High School English Text Books Based on Bloom's Revised Taxonomy

    Science.gov (United States)

    Rahpeyma, Ayoub; Khoshnood, Ali

    2015-01-01

    This study was carried out to evaluate the Iranian junior high school English text books according to learning objectives of Bloom's Revised Taxonomy (BRT) (2001) to find which learning levels of Bloom's Revised Taxonomy were more common in these text books. The primary data in this study came from the newly published English text book,…

  17. Bloom dynamics and life cycle strategies of two toxic dinoflagellates in a coastal upwelling system (NW Iberian Peninsula)

    Science.gov (United States)

    Bravo, Isabel; Fraga, Santiago; Isabel Figueroa, Rosa; Pazos, Yolanda; Massanet, Ana; Ramilo, Isabel

    2010-02-01

    A study of Gymnodinium catenatum and Alexandrium minutum blooms on the Galician coast was conducted from 2005 to 2007 in order to increase knowledge of the mechanisms governing recurrent blooms of these species. Considerable differences in their bloom dynamics were observed. G. catenatum blooms occurred in autumn and winter, following the pattern previously reported in the literature: they began off-shore and were advected to the Galician rias when a relaxation of the coastal upwelling occurred. On the other hand, A. minutum blooms developed inside embayments in spring and summer during the upwelling season and were associated with water stability and stratification. Both the vegetative population and the cyst distribution of A. minutum were related to less saline water from freshwater river outputs, which support a saline-gradient relationship postulated herein for this species. Dinoflagellates may produce both long-term double-walled cysts (resting) and short-term pellicle cysts. Resting cyst deposition and distribution in sediments showed that seeding occurred during the blooms of both species. However, the relationship between the cyst distribution in the sediments in Baiona Bay and the intensity and occurrence of G. catenatum blooms, suggests that the latter are not directly related to resting cyst germination. Moreover, the results presented in the present study point to other difference between the two species, such as the detection of pellicle cysts only for A. minutum. Finally, we discuss how the life cycle strategies of these two species may help to explain the different mechanisms of bloom formation reported herein.

  18. On the occurrence of blooms of blue-green algae and the associated oceanographic conditions in the Northern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Jayaraman, R.

    A survey of the existing literature on the occurrence of special blooms of planktonic algae and the phenomena such as Red Tide in the Northern Indian Ocean has been attempted The paper describes the occurrence of blooms of the blue-green alga...

  19. Study of ecological consequence of the bloom (Noctiluca miliaris) in off shore waters of the Northern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Dwivedi, R.M.; Chauhan, R.; Solanki, H.U.; Raman, M.; Matondkar, S.G.P.; Madhu, V.R.; Meenakumari, B.

    , NO. 4, AUGUST 2012 306 Schools of flying fishes and large size squids were observed during night at one bloom station in March 2007 (FORV-253). Also, on one occasion baby sharks were found swimming inside the bloom patch. These observations...

  20. The fecal bacteria

    Science.gov (United States)

    Sadowsky, Michael J.; Whitman, Richard L.

    2011-01-01

    The Fecal Bacteria offers a balanced, integrated discussion of fecal bacteria and their presence and ecology in the intestinal tract of mammals, in the environment, and in the food supply. This volume covers their use in examining and assessing water quality in order to offer protection from illnesses related to swimming in or ingesting contaminated water, in addition to discussing their use in engineering considerations of water quality, modeling, monitoring, and regulations. Fecal bacteria are additionally used as indicators of contamination of ready-to-eat foods and fresh produce. The intestinal environment, the microbial community structure of the gut microbiota, and the physiology and genomics of this broad group of microorganisms are explored in the book. With contributions from an internationally recognized group of experts, the book integrates medicine, public health, environmental, and microbiological topics in order to provide a unique, holistic understanding of fecal bacteria. Moreover, it shows how the latest basic science and applied research findings are helping to solve problems and develop effective management strategies. For example, readers will discover how the latest tools and molecular approaches have led to our current understanding of fecal bacteria and enabled us to improve human health and water quality. The Fecal Bacteria is recommended for microbiologists, clinicians, animal scientists, engineers, environmental scientists, food safety experts, water quality managers, and students. It will help them better understand fecal bacteria and use their knowledge to protect human and environmental health. They can also apply many of the techniques and molecular tools discussed in this book to the study of a broad range of microorganisms in a variety of habitats.

  1. Basin-wide seasonal evolution of the Indian Ocean's phytoplankton blooms

    Digital Repository Service at National Institute of Oceanography (India)

    Levy, M.; Shankar, D.; Andre, J.M.; Shenoi, S.S.C.; Durand, F.; DeBoyer Montegut, C.

    Sri Lanka up to the southwestern Bay of Bengal,244 in the northwest Bay of Bengal, along the coast of Indonesia, and in a subtropical band245 centered on 13.5 ◦ S. During winter (Figure 3b), the main blooms were in the northern246 Arabian Sea... the tongue-shaped region to the east of Sri Lanka (SL), the North West Bay of Bengal278 (NWBoB), a region along the coast of Indonesia (In), and a Tropical Band (TrB) located279 between 10–17 ◦ S.280 In the case of the winter blooms, this method led...

  2. Development of the composition of chocolate mass that resistant to bloom

    Directory of Open Access Journals (Sweden)

    M. E. Tkeshelashvili

    2017-01-01

    Full Text Available Chocolate or used as a coating on the surface of the sweets chocolate mass when exposed to a temperature drop and/or a drop in the humidity of the environment, change color, lose gloss and acquire an unwanted grayish-white surface. The loss of the appearance of chocolate – the effect of bloom is the reason for the return of products from the trading network causing highly tangible the economic damage to the producers. In this connection, experimental researches devoted to the problem of preventing bloom and developing consist of chocolate masses preclusion to bloom appear to be an urgent task. The purpose of the research is develop consist of chocolate and covering chocolate resistant to bloom. The work is performed at the Scientific research institute of «Applied research of innovative technologies and food quality» of Plekhanov Russian University of Economics. For an investigation, samples of chocolate and covering chocolate based on cocoa butter were made in the formulation of which an additive including milk fat/isomalt/polydextrose. The control samples were dark chocolate and covering chocolate prepared according to a unified formula. For the formation of blooming, the samples were exposed to temperature fluctuations and relative humidity. The measurement of the color of chocolate is implementation by an instrumental method based on the analysis of the optical characteristics of the product. The coefficients of reflection spectra of samples of chocolate were converted into color coordinates of space CIEL ? a ? b* 1976. The emergence of a bloom of chocolate by changing the parameter lightness L ? (CIEL ? a ? b* was diagnosed. The effect of introducing an additive, including milk fat/isomalt/polydextrose on fat and sugar bloom, was determined in the formulation of chocolate masses. Based on research the consist of the chocolate mass has been developed which practically does not change the taste of the finished chocolate products

  3. Approaches to monitoring, control and management of harmful algal blooms (HABs)

    OpenAIRE

    Anderson, Donald M.

    2009-01-01

    Virtually every coastal country in the world is affected by harmful algal blooms (HABs, commonly called “red tides”). These phenomena are caused by blooms of microscopic algae. Some of these algae are toxic, and can lead to illness and death in humans, fish, seabirds, marine mammals, and other oceanic life, typically as a result of the transfer of toxins through the food web. Sometimes the direct release of toxic compounds can be lethal to marine animals. Non-toxic HABs cause damage to ecosys...

  4. Autonomous Sampling of Remote Phytoplankton Blooms in the North Pacific Subtropical Gyre (July-Aug. 2015).

    Science.gov (United States)

    Anderson, E. E.; Wilson, C.; Villareal, T. A.

    2016-12-01

    Satellite ocean color data regularly reveals the existence of large (103 km2) phytoplankton blooms in the North Pacific Ocean that can persist for weeks to months and are often associated with N2 fixing diatom symbioses. The basin size and inability to accurately forecast these blooms makes sampling these events difficult outside of the time series at Station ALOHA. We used an autonomous Wave Glider surface vehicle (Honey Badger) to conduct a large regional survey well north of HI to examine bloom composition and key species distribution. Honey Badger was equipped with a gpCTD, downward looking camera, 2 C3 fluorometers, wind and wave sensors, a Turner Designs' Phytoflash, and a Sequoia Scientific LISST-Holo for imaging cells. Most of the data collected was available in near-real time through NOAA's ERDDAP data server. The 159 day mission began 1 June 2015 and covered 6800 km. From 1 July 2015 to 31 August 2015, Honey Badger transited from low levels of chlorophyll-a (chl) (0.06±0.01 mg m-3), through a mesoscale­ bloom, and then into a broad regional chl increase (0.08±0.01 mg m-3) as noted by the AQUA MODIS satellite. Phytoplankton cell counts (> 14,000 Hemiaulus cells L-1) and increased nocturnal Fv:Fm yields (maximum > 0.61) were concurrent with the 0.1 µg Chl L-1 bloom. A separate bloom of the Rhizosolenia-Richelia symbiosis was noted (> 3,000 Rhizosolenia-Richelia cells L-1) within a smaller, short-lived bloom with a biovolume 2.1 times higher than the rest of the southern transect. The broad regional chl increase in the southern leg of the transit was concurrent with a sustained Hemiaulus increase to 102 cells L-1. Diel patterns in Fv:Fm did not suggest Fe limitation anywhere in the transect. Elevated yields were found only in the diatom increases. Honey Badger and the instruments it carried were useful tools for the investigation of remote bloom dynamics in the Eastern North Pacific Subtropical Gyre.

  5. Phylogenetic structure of bacterial assemblages co-occurring with Ostreopsis cf. ovata bloom.

    Science.gov (United States)

    Vanucci, Silvana; Guidi, Flavio; Pistocchi, Rossella; Long, Richard A

    2016-05-01

    Extensive blooms of the toxic epiphytic/benthic dinoflagellate Ostreopsis cf. ovata are being reported with increasing frequency and spatial distribution in temperate coastal regions including the Mediterranean. These blooms are of human and environmental health concern due to the production of isobaric palytoxin and a wide range of ovatoxins by Ostreopsis cf. ovata. Bacterial-microalgal interactions are important regulators in algal bloom dynamics and potentially toxin dynamics. This study investigated the bacterial assemblages co-occurring with O. cf. ovata (OA) and from ambient seawaters (SW) during the early and peak phases of bloom development in NW Adriatic Sea. Fractions of the bacterial assemblages co-occurring with O. cf. ovata (OA) and more closely associated to the mucilage layer (LA) embedding O. cf. ovata cells were also reported. In total, 14 bacterial phyla were detected by targeted 454 pyrosequencing of the 16S rRNA gene. The dominant bacterial phyla in the OA assemblages were Proteobacteria and Bacteroidetes; while at the class level, Alphaproteobacteria were the most abundant (83 and 66%, relative abundance, early and peak bloom phases), followed by Flavobacteria (7 and 19%, early and peak phases). Actinobacteria and Cyanobacteria were of minor importance (<5% of the relative bacterial abundance each). Gammaproteobacteria showed a notably presence in OA assemblage only at the early phase of the bloom (genus Haliea, 13%). The Alphaproteobacteria were predominately composed by the genera Ruegeria, Jannaschia and Erythrobacter which represented about half of the total phylotypes' contribution of OA at both early and peak phases of the O. cf. ovata bloom, suggesting interactions between this consortium and the microalga. Moreover, the highest contribution of Ruegeria (30% of the total phylotypes) was observed at the early phase of the bloom in LA assemblage. Microbial assemblages associated with the ambient seawaters while being also dominated by

  6. Tumour targeting with systemically administered bacteria.

    LENUS (Irish Health Repository)

    Morrissey, David

    2012-01-31

    Challenges for oncology practitioners and researchers include specific treatment and detection of tumours. The ideal anti-cancer therapy would selectively eradicate tumour cells, whilst minimising side effects to normal tissue. Bacteria have emerged as biological gene vectors with natural tumour specificity, capable of homing to tumours and replicating locally to high levels when systemically administered. This property enables targeting of both the primary tumour and secondary metastases. In the case of invasive pathogenic species, this targeting strategy can be used to deliver genes intracellularly for tumour cell expression, while non-invasive species transformed with plasmids suitable for bacterial expression of heterologous genes can secrete therapeutic proteins locally within the tumour environment (cell therapy approach). Many bacterial genera have been demonstrated to localise to and replicate to high levels within tumour tissue when intravenously (IV) administered in rodent models and reporter gene tagging of bacteria has permitted real-time visualisation of this phenomenon. Live imaging of tumour colonising bacteria also presents diagnostic potential for this approach. The nature of tumour selective bacterial colonisation appears to be tumour origin- and bacterial species- independent. While originally a correlation was drawn between anaerobic bacterial colonisation and the hypoxic nature of solid tumours, it is recently becoming apparent that other elements of the unique microenvironment within solid tumours, including aberrant neovasculature and local immune suppression, may be responsible. Here, we consider the pre-clinical data supporting the use of bacteria as a tumour-targeting tool, recent advances in the area, and future work required to develop it into a beneficial clinical tool.

  7. Synthesis of Metal Nanoparticles by Bacteria

    Directory of Open Access Journals (Sweden)

    Fikriye Alev Akçay

    2018-04-01

    Full Text Available Metal particles reduced to nano size by nanotechnological methods are confronted in many different fields such as biomedical and physicochemical, pharmaceutical, electric-electronic, automotive and food industries. Nanoparticles can be produced using chemical, physical and biological methods, of which chemical processes are in common use. However, physical and chemical methods are not environmentally friendly and economical because they require the use of high temperature, high pressure and toxic chemicals. For this reason, interest in the production of metal nanoparticles by biological methods, also called green technology, an environmentally friendly and sustainable approach, has increased in recent years. With some plant extracts and intracellular and extracellular secretions of microorganisms, some reduction reactions take place and metal nanoparticles are produced. Bacteria have been actively involved in nanotechnology in recent years due to their diversity in nature, their ease of isolation, and ease of nanoparticle synthesis. In this article, production and application of metal nanoparticles by using bacterial methods have been reviewed.

  8. Magnetotactic bacteria. Promising biosorbents for heavy metals

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Wei; Zhang, Yanzong; Ding, Xiaohui; Liu, Yan; Shen, Fei; Zhang, Xiaohong; Deng, Shihuai; Xiao, Hong; Yang, Gang; Peng, Hong [Sichuan Agricultural Univ., Chengdu (China). Provincial Key Lab. of Agricultural Environmental Engineering

    2012-09-15

    Magnetotactic bacteria (MTB), which can orient and migrate along a magnetic line of force due to intracellular nanosized magnetosomes, have been a subject of research in the medical field, in dating environmental changes, and in environmental remediation. This paper reviews the recent development of MTB as biosorbents for heavy metals. Ultrastructures and taxis of MTB are investigated. Adsorptions in systems of unitary and binary ions are highlighted, as well as adsorption conditions (temperature, pH value, biomass concentration, and pretreatments). The separation and desorption of MTB in magnetic separators are also discussed. A green method to produce metal nanoparticles is provided, and an energy-efficient way to recover precious metals is put forward during biosorption. (orig.)

  9. Extracellular polysaccharides produced by marine bacteria.

    Science.gov (United States)

    Manivasagan, Panchanathan; Kim, Se-Kwon

    2014-01-01

    Extracellular polysaccharides (EPSs) produced by microorganisms are a complex mixture of biopolymers primarily consisting of polysaccharides, as well as proteins, nucleic acids, lipids, and humic substances. Microbial polysaccharides are multifunctional and can be divided into intracellular polysaccharides, structural polysaccharides, and extracellular polysaccharides or exopolysaccharides. Recent advances in biological techniques allow high levels of polysaccharides of interest to be produced in vitro. Biotechnology is a powerful tool to obtain polysaccharides from a variety of marine microorganisms, by controlling the growth conditions in a bioreactor while tailoring the production of biologically active compounds. The aim of this chapter is to give an overview of current knowledge on extracellular polysaccharides producing marine bacteria isolated from marine environment. © 2014 Elsevier Inc. All rights reserved.

  10. Transcriptional regulation of the Chlamydia heat shock stress response in an intracellular infection.

    Science.gov (United States)

    Hanson, Brett R; Tan, Ming

    2015-09-01

    Bacteria encode heat shock proteins that aid in survival during stressful growth conditions. In addition, the major heat shock proteins of the intracellular bacterium Chlamydia trachomatis have been associated with immune pathology and disease. We developed a ChIP-qPCR method to study the regulation of chlamydial heat shock gene regulation during an intracellular infection. This approach allowed us to show that chlamydial heat shock genes are regulated by the transcription factor HrcA within an infected cell, providing validation for previous in vitro findings. Induction of chlamydial heat shock gene expression by elevated temperature was due to loss of HrcA binding to heat shock promoters, supporting a mechanism of derepression. This heat shock response was rapid, whereas recovery of HrcA binding and return to non-stress transcript levels occurred more slowly. We also found that control of heat shock gene expression was differentially regulated over the course of the intracellular Chlamydia infection. There was evidence of HrcA-mediated regulation of heat shock genes throughout the chlamydial developmental cycle, but the level of repression was lower at early times. This is the first study of Chlamydia-infected cells showing the effect of an environmental signal on transcription factor-DNA binding and target gene expression in the bacterium. © 2015 John Wiley & Sons Ltd.

  11. Variability of factors driving spatial and temporal dispersion in river plume and Chattonella antiqua bloom in the Yatsushiro Sea, Japan.

    Science.gov (United States)

    Aoki, Kazuhiro; Onitsuka, Goh; Shimizu, Manabu; Kuroda, Hiroshi; Matsuo, Hitoshi; Kitadai, Yuuki; Sakurada, Kiyonari; Ando, Hidenori; Nishi, Hiromi; Tahara, Yoshio

    2014-04-15

    The dynamics of river plume in relation to harmful blooms of the raphidophycean flagellate, Chattonella antiqua in summer 2008-2010 in the Yatsushiro Sea, Japan were studied using a hydrodynamic model and monitoring data. In the southern area, the bloom formed in the waters stratified by a halocline caused by the southward expansion of riverine water from the Kuma River after the bloom initially forming in the northern area. The timing of the southward riverine water advection can be explained by the balance between the wind stress term and the pressure gradient term calculated from the horizontal density difference between the northern and southern areas. The wind stress and pressure gradient terms were evaluated using the sea surface temperature, salinity, wind speed and direction at two stations. Real time monitoring or continuous observations in these areas will enable nowcasts of bloom expansion when a bloom develops in the northern area. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Relationship between magnitude of phytoplankton blooms and rainfall in a hyper-eutrophic lagoon: A continuous monitoring approach.

    Science.gov (United States)

    Meng, Pei-Jie; Tew, Kwee Siong; Hsieh, Hung-Yen; Chen, Chung-Chi

    2017-11-30

    To evaluate the effect of rainfall intensity on phytoplankton blooms, a continuous monitoring system was deployed during 2015 in a hyper-eutrophic lagoon in Taiwan. Intensive rainfall occurs during the wet summer months, from May to September. Salinity in the lagoon was found to decrease with increasing intensity of rainfall. The magnitude of phytoplankton blooms also increased linearly with increasing rainfall intensity. The chlorophyll a concentration rose by an order of magnitude during the heaviest rainfall. Blooms may be fueled by nutrient enrichment caused by drainage or run-off water from surrounding areas that is channeled into the lagoon during rainfall events. During bloom periods, the rates of net primary production and ecosystem respiration were high. However, this ecosystem was autotrophic for most of the year. As extreme rainfall is predicted to increase, the results of this study imply that the frequency and magnitude of phytoplankton blooms may increase in the future. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Recurrent blooms of Heterosigma akashiwo (Raphidophyceae in the Piraquê Channel, Rodrigo de Freitas Lagoon, southeast Brazil

    Directory of Open Access Journals (Sweden)

    S Branco

    Full Text Available Six blooms of Heterosigma akashiwo(Raphidophyceae were observed from March 2007 through March 2008 in the Rodrigo de Freitas Lagoon, a semi-confined eutrophic system located in Rio de Janeiro state, southeast Brazil. Vegetative cells of H. akashiwo analysed by optical and electron microscopy showed morphology as described in the literature. The blooms (2.8 × 104 to 4 × 108 cell.L–1 were restricted to the middle section of the Piraquê Channel, which is situated in the northeastern part of the lagoon and receives freshwater inflow. The salinity of subsurface water and the channel depth showed significant negative correlations with H. akashiwo abundances, and appeared to restrict the blooms to this compartment of the lagoon. No fish mortality was associated with the H. akashiwo blooms, nor were brevetoxins detected in a cell extract obtained from the bloom observed on 19 March 2007.

  14. The fast expansion of Pyropia aquaculture in ;Sansha; regions should be mainly responsible for the Ulva blooms in Yellow Sea

    Science.gov (United States)

    Zhang, Jianheng; Zhao, Peng; Huo, Yuanzi; Yu, Kefeng; He, Peimin

    2017-04-01

    Massive Ulva blooms became an environmental disaster in the Yellow Sea from 2007 to 2015. In this study, field shipboard observations indicated that Ulva blooms originated in Pyropia aquaculture area, and the morphology of initial floating Ulva seaweed have the structure of rhizoid, which is similar with the attached Ulva on the Pyropia rafts. The spatial distribution of Ulva microscopic propagules in the southern Yellow Sea also supported that the blooms originated in the Pyropia aquaculture area. Besides, numerical model was used in this study, showing the origin of macroalgal blooms was traced to "Sansha" regions which accounted for almost 70% of the total Pyropia aquaculture area. We conclude that the significant biomass (4252 tons) of Ulva species on the Pyropia rafts during the harvesting season in "Sansha" regions played an important role in the early rapid development of blooms in the Yellow Sea.

  15. Insights into the genome of large sulfur bacteria revealed by analysis of single filaments

    DEFF Research Database (Denmark)

    Mussmann, Marc; Hu, Fen Z.; Richter, Michael

    2007-01-01

    Marine sediments are frequently covered by mats of the filamentous Beggiatoa and other large nitrate-storing bacteria that oxidize hydrogen sulfide using either oxygen or nitrate, which they store in intracellular vacuoles. Despite their conspicuous metabolic properties and their biogeochemical...

  16. An optimal method of iron starvation of the obligate intracellular pathogen, Chlamydia trachomatis

    Directory of Open Access Journals (Sweden)

    Christopher C. Thompson

    2011-02-01

    Full Text Available Iron is an essential cofactor in a number of critical biochemical reactions, and as such, its acquisition, storage, and metabolism is highly regulated in most organisms. The obligate intracellular bacterium, Chlamydia trachomatis experiences a developmental arrest when iron within the host is depleted. The nature of the iron starvation response in Chlamydia is relatively uncharacterized because of the likely inefficient method of iron depletion, which currently relies on the compound deferoxamine mesylate (DFO. Inefficient induction of the iron starvation response precludes the identification of iron-regulated genes. This report evaluated DFO with another iron chelator, 2,2’-bipyridyl (Bpdl and presented a systematic comparison of the two across a range of criteria in a single-treatment time-of-infection regimen. We demonstrate that the membrane permeable Bpdl was superior to DFO in the inhibition of chlamydia development, the induction of aberrant morphology, and the induction of an iron starvation transcriptional response in both host and bacteria. Furthermore, iron starvation using Bpdl identified the periplasmic iron binding protein-encoding ytgA gene as iron- responsive. Overall, the data present a compelling argument for the use of Bpdl, rather than DFO, in future iron starvation studies of chlamydia and other intracellular bacteria.

  17. Genome sequence of Rickettsia bellii illuminates the role of amoebae in gene exchanges between intracellular pathogens.

    Directory of Open Access Journals (Sweden)

    Hiroyuki Ogata

    2006-05-01

    Full Text Available The recently sequenced Rickettsia felis genome revealed an unexpected plasmid carrying several genes usually associated with DNA transfer, suggesting that ancestral rickettsiae might have been endowed with a conjugation apparatus. Here we present the genome sequence of Rickettsia bellii, the earliest diverging species of known rickettsiae. The 1,552,076 base pair-long chromosome does not exhibit the colinearity observed between other rickettsia genomes, and encodes a complete set of putative conjugal DNA transfer genes most similar to homologues found in Protochlamydia amoebophila UWE25, an obligate symbiont of amoebae. The genome exhibits many other genes highly similar to homologues in intracellular bacteria of amoebae. We sought and observed sex pili-like cell surface appendages for R. bellii. We also found that R. bellii very efficiently multiplies in the nucleus of eukaryotic cells and survives in the phagocytic amoeba, Acanthamoeba polyphaga. These results suggest that amoeba-like ancestral protozoa could have served as a genetic "melting pot" where the ancestors of rickettsiae and other bacteria promiscuously exchanged genes, eventually leading to their adaptation to the intracellular lifestyle within eukaryotic cells.

  18. Chlorosomes: antenna organelles in photosynthetic green bacteria

    DEFF Research Database (Denmark)

    Frigaard, N.-U.; Bryant, D. A.

    2006-01-01

    The new series "Microbiology Monographs" begins with two volumes on intracellular components in prokaryotes. In this second volume, "Complex Intracellular Structures in Prokaryotes", the components, labelled complex intracellular structures, encompass a multitude of important cellular functions. ...

  19. Intracellular pH in sperm physiology.

    Science.gov (United States)

    Nishigaki, Takuya; José, Omar; González-Cota, Ana Laura; Romero, Francisco; Treviño, Claudia L; Darszon, Alberto

    2014-08-01

    Intracellular pH (pHi) regulation is essential for cell function. Notably, several unique sperm ion transporters and enzymes whose elimination causes infertility are either pHi dependent or somehow related to pHi regulation. Amongst them are: CatSper, a Ca(2+) channel; Slo3, a K(+) channel; the sperm-specific Na(+)/H(+) exchanger and the soluble adenylyl cyclase. It is thus clear that pHi regulation is of the utmost importance for sperm physiology. This review briefly summarizes the key components involved in pHi regulation, their characteristics and participation in fundamental sperm functions such as motility, maturation and the acrosome reaction. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Drosophila VAMP7 regulates Wingless intracellular trafficking.

    Science.gov (United States)

    Gao, Han; He, Fang; Lin, Xinhua; Wu, Yihui

    2017-01-01

    Drosophila Wingless (Wg) is a morphogen that determines cell fate during development. Previous studies have shown that endocytic pathways regulate Wg trafficking and signaling. Here, we showed that loss of vamp7, a gene required for vesicle fusion, dramatically increased Wg levels and decreased Wg signaling. Interestingly, we found that levels of Dally-like (Dlp), a glypican that can interact with Wg to suppress Wg signaling at the dorsoventral boundary of the Drosophila wing, were also increased in vamp7 mutant cells. Moreover, Wg puncta in Rab4-dependent recycling endosomes were Dlp positive. We hypothesize that VAMP7 is required for Wg intracellular trafficking and the accumulation of Wg in Rab4-dependent recycling endosomes might affect Wg signaling.

  1. Intracellular Signalling by C-Peptide

    Directory of Open Access Journals (Sweden)

    Claire E. Hills

    2008-01-01

    Full Text Available C-peptide, a cleavage product of the proinsulin molecule, has long been regarded as biologically inert, serving merely as a surrogate marker for insulin release. Recent findings demonstrate both a physiological and protective role of C-peptide when administered to individuals with type I diabetes. Data indicate that C-peptide appears to bind in nanomolar concentrations to a cell surface receptor which is most likely to be G-protein coupled. Binding of C-peptide initiates multiple cellular effects, evoking a rise in intracellular calcium, increased PI-3-kinase activity, stimulation of the Na+/K+ ATPase, increased eNOS transcription, and activation of the MAPK signalling pathway. These cell signalling effects have been studied in multiple cell types from multiple tissues. Overall these observations raise the possibility that C-peptide may serve as a potential therapeutic agent for the treatment or prevention of long-term complications associated with diabetes.

  2. Intracellular Na⁺ and cardiac metabolism.

    Science.gov (United States)

    Bay, Johannes; Kohlhaas, Michael; Maack, Christoph

    2013-08-01

    In heart failure, alterations of excitation-contraction underlie contractile dysfunction. One important defect is an elevation of the intracellular Na(+) concentration in cardiac myocytes ([Na(+)]i), which has an important impact on cytosolic and mitochondrial Ca(2+) homeostasis. While elevated [Na(+)]i is thought to compensate for decreased Ca(2+) load of the sarcoplasmic reticulum (SR), it yet negatively affects energy supply-and-demand matching and can even induce mitochondrial oxidative stress. Here, we review the mechanisms underlying these pathophysiological changes. The chain of events may constitute a vicious cycle of ion dysregulation, oxidative stress and energetic deficit, resembling characteristic cellular deficits that are considered key hallmarks of the failing heart. This article is part of a Special Issue entitled "Na(+) Regulation in Cardiac Myocytes". Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. An intracellular anion channel critical for pigmentation.

    Science.gov (United States)

    Bellono, Nicholas W; Escobar, Iliana E; Lefkovith, Ariel J; Marks, Michael S; Oancea, Elena

    2014-12-16

    Intracellular ion channels are essential regulators of organellar and cellular function, yet the molecular identity and physiological role of many of these channels remains elusive. In particular, no ion channel has been characterized in melanosomes, organelles that produce and store the major mammalian pigment melanin. Defects in melanosome function cause albinism, characterized by vision and pigmentation deficits, impaired retinal development, and increased susceptibility to skin and eye cancers. The most common form of albinism is caused by mutations in oculocutaneous albinism II (OCA2), a melanosome-specific transmembrane protein with unknown function. Here we used direct patch-clamp of skin and eye melanosomes to identify a novel chloride-selective anion conductance mediated by OCA2 and required for melanin production. Expression of OCA2 increases organelle pH, suggesting that the chloride channel might regulate melanin synthesis by modulating melanosome pH. Thus, a melanosomal anion channel that requires OCA2 is essential for skin and eye pigmentation.

  4. Nanobodies: Chemical Functionalization Strategies and Intracellular Applications

    Science.gov (United States)

    Schumacher, Dominik; Helma, Jonas; Schneider, Anselm F. L.; Leonhardt, Heinrich

    2018-01-01

    Abstract Nanobodies can be seen as next‐generation tools for the recognition and modulation of antigens that are inaccessible to conventional antibodies. Due to their compact structure and high stability, nanobodies see frequent usage in basic research, and their chemical functionalization opens the way towards promising diagnostic and therapeutic applications. In this Review, central aspects of nanobody functionalization are presented, together with selected applications. While early conjugation strategies relied on the random modification of natural amino acids, more recent studies have focused on the site‐specific attachment of functional moieties. Such techniques include chemoenzymatic approaches, expressed protein ligation, and amber suppression in combination with bioorthogonal modification strategies. Recent applications range from sophisticated imaging and mass spectrometry to the delivery of nanobodies into living cells for the visualization and manipulation of intracellular antigens. PMID:28913971

  5. What are the effects of macroalgal blooms on the structure and functioning of marine ecosystems? A systematic review protocol

    Directory of Open Access Journals (Sweden)

    Lyons Devin A

    2012-06-01

    Full Text Available Abstract Background Anthropogenic activities are believed to have caused an increase in the magnitude, frequency, and extent of macroalgal blooms in marine and estuarine environments. These blooms may contribute to declines in seagrasses and non-blooming macroalgal beds, increasing hypoxia, and reductions in the diversity of benthic invertebrates. However, they may also provide other marine organisms with food and habitat, increase secondary production, and reduce eutrophication. The objective of this systematic review will be to quantify the positive and negative impacts of anthropogenically induced macroalgal blooms in order to determine their effects on ecosystem structure and functioning, and to identify factors that cause their effects to vary. Methods We will search a number of online databases to gather empirical evidence from the literature on the impacts of macroalgal blooms on: (1 species richness and other univariate measures of biodiversity; (2 productivity and abundance of algae, plants, and animals; and (3 biogeochemical cycling and other flows of energy and materials, including trophic interactions and cross-ecosystem subsidies. Data from relevant studies will be extracted and used in a random effects meta-analysis in order to estimate the average effect of macroalgal blooms on each response of interest. Where possible, sub-group analyses will be conducted in order to evaluate how the effects of macroalgal blooms vary according to: (1 which part of the ecosystem is being studied (e.g. which habitat type, taxonomic group, or trophic level; (2 the size of blooms; (3 the region in which blooms occurred; (4 background levels of ecosystem productivity; (5 physical and chemical conditions; (6 aspects of study design and quality (e.g. lab vs. field, experimental vs. observational, degree of replication; and (7 whether the blooms are believed to be anthropogenically induced or not.

  6. Culturable bacterial flora associated with the dinoflagellate green Noctiluca miliaris during active and declining bloom phases in the Northern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Basu, S.; Deobagkar, D.D.; Matondkar, S.G.P.; Furtado, I.

    bloom were approx. 2-3-fold higher in comparison to non-bloom waters and ranged from 3.20×10 sup(5) to 6.84×10 sup(5) cfu ml sup(-1). An analysis of the dominant heterotrophs associated with Noctiluca bloom resulted in phylogenetic and a detailed...

  7. Mycorrhiza helper bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Deveau, Aurelie [French National Insitute for Agricultural Research (INRA); Labbe, Jessy [ORNL

    2016-10-01

    This chapter focuses on the Mycorrhiza Helper Bacteria (MHB), a generic name given to bacteria which stimulate the formation of mycorrhizal symbiosis. By extension, some bacterial strains that positively impact the functioning of mycorrhizal symbiosis are also called MHB. These bacteria have applicative interests, as they indirectly improve the health and growth of tree seedlings. MHB are not restricted to a specific type of ecosystem, but are rather generalist in the way that they associate with both herbaceous and woody mycorrhizal plants from boreal, temperate, arid and tropical ecosystems. However, understanding the molecular mechanisms and their specificities will help us to know more about the ecology of the MHB. The process of acquisition varies between fungal species; while ectomycorrhizal fungi most probably recurrently acquire them from the environment, the association between bacterial endosymbionts and Glomeromycota probably dates back to very ancient times, and has since been vertically transmitted.

  8. The Role of Autophagy in Intracellular Pathogen Nutrient Acquisition

    Directory of Open Access Journals (Sweden)

    Shaun eSteele

    2015-06-01

    Full Text Available Following entry into host cells intracellular pathogens must simultaneously evade innate host defense mechanisms and acquire energy and anabolic substrates from the nutrient-limited intracellular environment. Most of the potential intracellular nutrient sources are stored within complex macromolecules that are not immediately accessible by intracellular pathogens. To obtain nutrients for proliferation, intracellular pathogens must compete with the host cell for newly-imported simple nutrients or degrade host nutrient storage structures into their constituent components (fatty acids, carbohydrates and amino acids. It is becoming increasingly evident that intracellular pathogens have evolved a wide variety of strategies to accomplish this task. One recurrent microbial strategy is to exploit host degradative processes that break down host macromolecules into simple nutrients that the microbe can use. Herein we focus on how a subset of bacterial, viral and eukaryotic pathogens leverage the host process of autophagy to acquire nutrients that support their growth within infected cells

  9. Involvement of indole-3-acetic acid produced by Azospirillum brasilense in accumulating intracellular ammonium in Chlorella vulgaris.

    Science.gov (United States)

    Meza, Beatriz; de-Bashan, Luz E; Bashan, Yoav

    2015-01-01

    Accumulation of intracellular ammonium and activities of the enzymes glutamine synthetase (GS) and glutamate dehydrogenase (GDH) were measured when the microalgae Chlorella vulgaris was immobilized in alginate with either of two wild type strains of Azospirillum brasilense or their corresponding indole-3-acetic acid (IAA)-attenuated mutants. After 48 h of immobilization, both wild types induced higher levels of intracellular ammonium in the microalgae than their respective mutants; the more IAA produced, the higher the intracellular ammonium accumulated. Accumulation of intracellular ammonium in the cells of C. vulgaris followed application of four levels of exogenous IAA reported for A. brasilense and its IAA-attenuated mutants, which had a similar pattern for the first 24 h. This effect was transient and disappeared after 48 h of incubation. Immobilization of C. vulgaris with any bacteria strain induced higher GS activity. The bacterial strains also had GS activity, comparable to the activity detected in C. vulgaris, but weaker than when immobilized with the bacteria. When net activity was calculated, the wild type always induced higher GS activity than IAA-attenuated mutants. GDH activity in most microalgae/bacteria interactions resembled GS activity. When complementing IAA-attenuated mutants with exogenous IAA, GS activity in co-immobilized cultures matched those of the wild type A. brasilense immobilized with the microalga. Similarity occurred when the net GS activity was measured, and was higher with greater quantities of exogenous IAA. It is proposed that IAA produced by A. brasilense is involved in ammonium uptake and later assimilation by C. vulgaris. Copyright © 2014 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  10. Strategies of Intracellular Pathogens for Obtaining Iron from the Environment

    Directory of Open Access Journals (Sweden)

    Nidia Leon-Sicairos

    2015-01-01

    Full Text Available Most microorganisms are destroyed by the host tissues through processes that usually involve phagocytosis and lysosomal disruption. However, some organisms, called intracellular pathogens, are capable of avoiding destruction by growing inside macrophages or other cells. During infection with intracellular pathogenic microorganisms, the element iron is required by both the host cell and the pathogen that inhabits the host cell. This minireview focuses on how intracellular pathogens use multiple strategies to obtain nutritional iron from the intracellular environment in order to use this element for replication. Additionally, the implications of these mechanisms for iron acquisition in the pathogen-host relationship are discussed.

  11. Great Lake beach-goer behavior during a retrospectively detected bloom of cyanobacteria

    Science.gov (United States)

    Cyanobacteria blooms pose a potential health risk to beachgoers. We conducted a prospective study of weekend beachgoers at a public Great Lake site during July – September 2003. We recorded each person’s health status and activity during their beach visit. We measured...

  12. FEM Simulation Of Stress-Strain Fields in the Blooms with Casting Defect During Soaking

    Directory of Open Access Journals (Sweden)

    Miroslav KVÍČALA

    2013-06-01

    Full Text Available Round continuously cast blooms heating strategy is crucial in prevention of internal cracks initiation and propagation. Especially vanadium microalloyed Cr-Mo based steels are very sensitive to internal crack occurrence. This paper deals with two heating strategies that were realized in soaking pit. Using FEM simulation it was proved that proper heating strategy is essential to reduce internal crack propagation.

  13. Impact of elevated pH on succession in the Arctic spring bloom

    DEFF Research Database (Denmark)

    Riisgaard, Karen; Nielsen, Torkel Gissel; Hansen, Per Juel

    2015-01-01

    at the initiation of the spring bloom each year and manipulated to cover pH levels in the range of 8.0-9.5 to test the immediate tolerance of Arctic protist plankton to elevated pH under nutrient-limiting (2011) and nutrient-rich conditions (2012). The most pronounced effect of elevated pH was found......The development of pH during the spring bloom in 2011 and 2012 was investigated in Disko Bay, West Greenland. During the spring phytoplankton bloom pH reached 8.5 at the peak of the bloom. Subsequently, the pH decreased to 7.5. Microcosm experiments were conducted on natural assemblages sampled...... for heterotrophic protists, whereas phytoplankton proved more robust. Two out of three heterotrophic protist species were significantly affected if pH increased above 8.5, and all heterotrophic protists had disappeared at pH 9.5. Based on Chl a measurements from the two sets of experiments, phytoplankton community...

  14. Remote Sensing as a Tool to Track Algal Blooms in the Great Salt Lake, Utah, USA

    Science.gov (United States)

    Bradt, S. R.; Wurtsbaugh, W. A.; Naftz, D.; Moore, T.; Haney, J.

    2006-12-01

    The Great Salt Lake is a large hypersaline, terminal water body in northern Utah, USA. The lake has both a significant economic importance to the local community as a source of brine shrimp and mineral resources, as well as, an ecological importance to large numbers of migratory waterfowl. Due to nutrient input from sewage treatment plants, sections of the Great Salt Lake are subjected to highly eutrophic conditions. One of the main tributaries, Farmington Bay, experiences massive blooms of cyanobacteria which can reach concentrations in excess of 300 mg l-1 in the bay. Effects of these blooms can be observed stretching into the rest of the lake. The detrimental outcomes of the blooms include unsightly scums, foul odor and the danger of cyanobacterial toxins. While the blooms have an obvious effect on Farmington Bay, it is quite possible that the cyanobacteria impact a much wider area of the lake as currents move eutrophic water masses. Of particular interest is the reaction of brine shrimp to the plumes of cyanobacteria-rich water leaving Farmington Bay. We are employing remote sensing as a tool to map the distribution of algae throughout the lake and produce lake-wide maps of water quality on a regular basis. On-lake reflectance measurements have been coupled with MODIS satellite imagery to produce a time series of maps illustrating changes in algal distribution. The successes and shortcomings of our remote sensing technique will be a central topic of this presentation.

  15. Using Multi-media Modeling to Investigate Conditions Leading to Harmful Algal Blooms

    Science.gov (United States)

    Lake Erie is the twelfth largest lake in the world and provides drinking water to over 11 million people in the United States. 22,720 square miles of varying landcover (e.g., urban, agriculture) drain directly into Lake Erie. Harmful algal blooms (HABs) have historically been an ...

  16. Characterization of multiple isolates from an Alexandrium ostenfeldii bloom in The Netherlands

    NARCIS (Netherlands)

    Van de Waal, Dedmer B.; Tillmann, Urban; Martens, Helge; Krock, Bernd; van Scheppingen, Yvonne; John, Uwe

    2015-01-01

    Alexandrium ostenfeldii is an emerging harmful algal bloom species forming a global threat to coastal marine ecosystems, with consequences for fisheries and shellfish production. The Oosterschelde estuary is a shallow, macrotidal and mesotrophic estuary in the southwest of The Netherlands with large

  17. Bloom syndrome in short children born small for gestational age: A challenging diagnosis

    NARCIS (Netherlands)

    J.S. Renes (Judith); R.H. Willemsen (Ruben); A. Wagner (Anja); M.J. Finken (Martijn); A.C.S. Hokken-Koelega (Anita)

    2013-01-01

    textabstractBackground: GH treatment has become a frequently applied growth-promoting therapy in short children born small for gestational age (SGA). In some disorders GH treatment is contraindicated, eg, chromosomal breakage syndromes. Bloom syndrome is a rare chromosomal breakage syndrome

  18. Integrating the Revised Bloom's Taxonomy With Multiple Intelligences: A Planning Tool for Curriculum Differentiation

    Science.gov (United States)

    Noble, Toni

    2004-01-01

    Both the special education and gifted education literature call for a differentiated curriculum to cater for the wide range of student differences in any classroom. Gardner's theory of multiple intelligences was integrated with the revised Bloom's taxonomy to provide a planning tool for curriculum differentiation. Teachers' progress in using the…

  19. Revised Bloom's Taxonomy and Integral Calculus: Unpacking the Knowledge Dimension

    Science.gov (United States)

    Radmehr, Farzad; Drake, Michael

    2017-01-01

    In this paper, the knowledge dimension for Revised Bloom's taxonomy (RBT) is unpacked for integral calculus. As part of this work, the 11 subtypes of the knowledge dimension are introduced, and through document analysis of chapter 4 of the RBT handbook, these subtypes are defined. Then, by consulting materials frequently used for teaching integral…

  20. A Comparison of Revised Bloom and Marzano's New Taxonomy of Learning

    Science.gov (United States)

    Irvine, Jeff

    2017-01-01

    The seminal "Taxonomy of Educational Objectives: The Classification of Educational Goals--Handbook I, Cognitive Domain" (Bloom, Engelhart, Furst, Hill, & Krathwohl, 1956) represented years of collaboration by the Committee of College and University Examiners, and was the first of three volumes that together would become known as…