1,721,035 research outputs found
Molecular and cellular processes of the innate immune response in insects: investigation on the immune modulation induced by entomopathogenic nematodes
Full text linkAim of this project was to investigate relationships between Rhynchophorus ferrugineus or Galleria mellonella and the entomopathogenic nematode Steinernema carpocapsae. In particular, the work was focused on the immune response of the insect host either in naïve larvae or in larvae infected with entomoparasites. We analyzed different immunological processes: the activity and modulation of prophenoloxidase-phenoloxidase (proPO) system, the cell-mediated encapsulation, the antimicrobial peptides (AMPs) inducible response and finally the phagocytosis activity of the host hemocytes. Furthermore, we investigated the immune depressive and immune evasive strategies of the parasite. Our results indicated that R. ferrugineus has an efficient immune system; however, in the early phase of infection, the presence of S. carpocapsae induces a strong inhibition of the host proPO system. In addition, the parasite does not seem to be susceptible to the encapsulation by host hemocytes; the parasite mimetic properties seem to be related to the structure of its body surface. S. carpocapsae, before the release of its symbiotic bacteria (X. nematophila), depresses and elude the host immune defenses, with the aim to create a favorable environment for its symbionts responsible of the septicemic death of the insect host. Besides, our results have demonstrated that X. nematophila is able to inhibit the synthesis and the activity of antimicrobial peptides. X .nematophila elude the recognition by hemocytes since it is not engulfed by the host cells. It is evident that the nematode and its symbiotic bacteria cooperate to elude and inhibit immune responses of the insect host. This study provides data that can help to a better understand of the relationships between parasites and their hosts
Pilot scale polyhydroxyalkanoates-production from organic fraction of municipal solid waste by Hydrogenophaga species
No full textPlastic pollution represents a worldwide threat to environment, nevertheless during last decades promising alternatives to conventional plastics have been investigated. The use of biodegradable polymers produced by microorganisms, such as polyhydroxyalkanoates (PHA), are of high interest due to their thermo-plastic properties. Recently, the PHA-production from the Organic Fraction of Municipal Solid Waste (OFMSW) was successfully reported at pilot scale. In particular, this work is aimed at evaluating the microbial community dynamics during plant operation (around 200 days) and correlating the occurrence of specific PHA accumulating bacteria to process parameters (e.g. temperature, Volatile Fatty Acids composition, PHA content, Organic Loading Rate). Temporal changes in microbial community composition were described by high-throughput 16S rRNA gene sequencing and the outputs of the analysis were validated by applying
specific FISH oligonucleotide probes. The Nile blue staining, specific for the detection of intracellular lipid inclusions, confirmed that the whole biomass was able to store PHA granules. Members of Hydrogenophaga genus were main PHA accumulating bacteria and found associated to the maximum PHA storage capacity.
This genus strongly increased overtime together with the appearance of functional gene (phaC) coding for PHA synthase
Metagenomic analysis reveals microbial interactions at the biocathode of a bioelectrochemical system capable of simultaneous trichloroethylene and cr(vi) reduction
Full text linkBioelectrochemical systems (BES) are attractive and versatile options for the bioremediation of organic or inorganic pollutants, including trichloroethylene (TCE) and Cr(VI), often found as co-contaminants in the environment. The elucidation of the microbial players’ role in the bioelectroremediation processes for treating multicontaminated groundwater is still a research need that attracts scientific interest. In this study, 16S rRNA gene amplicon sequencing and whole shotgun metagenomics revealed the leading microbial players and the primary metabolic interactions occurring in the biofilm growing at the biocathode where TCE reductive dechlorination (RD), hydrogenotrophic methanogenesis, and Cr(VI) reduction occurred. The presence of Cr(VI) did not negatively affect the TCE degradation, as evidenced by the RD rates estimated during the reactor operation with TCE (111±2 μeq/Ld) and TCE/Cr(VI) (146±2 μeq/Ld). Accordingly, Dehalococcoides mccartyi, the primary biomarker of the RD process, was found on the biocathode treating both TCE (7.82E+04±2.9E+04 16S rRNA gene copies g−1 graphite) and TCE/Cr(VI) (3.2E+07±2.37E+0716S rRNA gene copies g−1 graphite) contamination. The metagenomic analysis revealed a selected microbial consortium on the TCE/Cr(VI) biocathode. D. mccartyi was the sole dechlorinating microbe with H2 uptake as the only electron supply mechanism, suggesting that electroactivity is not a property of this microorganism. Methanobrevibacter arboriphilus and Methanobacterium formicicum also colonized the biocathode as H2 consumers for the CH4 production and cofactor suppliers for D. mccartyi cobalamin biosynthesis. Interestingly, M. formicicum also harbors gene complexes involved in the Cr(VI) reduction through extracellular and intracellular mechanisms
Effects of an entomopathogen nematode on the immune response of the insect pest red palm weevil: Focus on the host antimicrobial response
No full textRelationships between parasites and hosts can be drastic, depending on the balance between parasite strategies and the efficiency of the host immune response. In the case of entomopathogenic nematodes and their insect hosts, we must also consider the role of bacterial symbionts, as the interaction among them is tripartite and each component plays a critical role in death or survival. We analyzed the effects induced by the nematode–bacteria complex Steinernema carpocapsae, against red palm weevil (RPW) larvae, Rhynchophorus ferrugineus. We examined the antimicrobial response of the insect when in the presence of nematocomplexes or of its symbionts, Xenorhabdus nematophila. In detail, we investigated the potential interference of live and dead S. carpocapsae, their isolated cuticles, live or dead bacterial symbionts and their lipopolysaccharides, on the synthesis and activity of host antimicrobial peptides. Our data indicate that both live nematodes and live bacterial symbionts are able to depress the host antimicrobial response. When nematodes or symbionts were killed, they lacked inhibitory properties, as detected by the presence of antimicrobial peptides (AMPs) in the host hemolymph and by assays of antimicrobial activity. Moreover, we isolated S. carpocapsae cuticles; when cuticles were injected into hosts they revealed evasive properties because they were not immunogenic and were not recognized by the host immune system. We observed that weevil AMPs did not damage X. nematophila, and the lipopolysaccharides purified from symbionts seemed to be non-immunogenic. We believe that our data provide more information on the biology of entomopathogenic nematodes, in particular concerning their role and the activity mediated by symbionts in the relationship with insect hosts.Relationships between parasites and hosts can be drastic, depending on the balance between parasite strategies and the efficiency of the host immune response. In the case of entomopathogenic nematodes and their insect hosts, we must also consider the role of bacterial symbionts, as the interaction among them is tripartite and each component plays a critical role in death or survival. We analyzed the effects induced by the nematode-bacteria complex Steinernema carpocapsae, against red palm weevil (RPW) larvae, Rhynchophorus ferrugineus. We examined the antimicrobial response of the insect when in the presence of nematocomplexes or of its symbionts, Xenorhabdus nematophila. In detail, we investigated the potential interference of live and dead S. carpocapsae, their isolated cuticles, live or dead bacterial symbionts and their lipopolysaccharides, on the synthesis and activity of host antimicrobial peptides. Our data indicate that both live nematodes and live bacterial symbionts are able to depress the host antimicrobial response. When nematodes or symbionts were killed, they lacked inhibitory properties, as detected by the presence of antimicrobial peptides (AMPs) in the host hemolymph and by assays of antimicrobial activity. Moreover, we isolated S. carpocapsae cuticles; when cuticles were injected into hosts they revealed evasive properties because they were not immunogenic and were not recognized by the host immune system. We observed that weevil AMPs did not damage X. nematophila, and the lipopolysaccharides purified from symbionts seemed to be non-immunogenic. We believe that our data provide more information on the biology of entomopathogenic nematodes, in particular concerning their role and the activity mediated by symbionts in the relationship with insect hosts
Reductive/oxidative sequential bioelectrochemical process for Perchloroethylene (PCE) removal: effect of the applied reductive potential and microbial community characterization
No full textIn this paper, a bioelectrochemical process has been developed by the combination of two membrane-less reactors equipped with an internal graphite granules counterelectrode for the perchloroethylene (PCE) removal through a reductive/oxidative sequence. In the reductive reactor, the cathodic chamber supplied the reducing power to PCE dechlorinating biomass while a rutile electrode promoted the aerobic dechlorination of the less chlorinated PCE byproducts by oxygen in situ evolution. Two potentiostatic conditions, -350 and -550 mV vs SHE, were tested on the reductive reactor, which showed the capability to completely reduce the PCE into vinyl chloride (VC) and ethylene (Eth). These compounds were completely removed by the oxidative reactor with an average VC and Eth removal efficiency of 94 ± 1% and 98 ± 1%. The -350 mV vs SHE condition resulted in the higher coulombic efficiency for the reductive dechlorination which reached 22 ± 7 % while by increasing the reductive potential to -550 mV the coulombic efficiency drop down to 6 ± 1 % in favor of the methanogenesis reaction. Dehalococcoides mccartyi was found at high abundance in the reducing reactor while a heterogeneous bacterial consortium was observed in the oxidative reactor. Microbiome characterization of the reductive and oxidative reactors showed the concomitant presence of different redox niches in each compartment suggesting that the exchange of ionic species between the electrode and the counterelectrode allowed the co-existence of both reducing and oxidative reactions. © 2020 The Author(s)
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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