1,721,000 research outputs found
Lignification: are lignins biosynthesized via simple combinatorial chemistry or via proteinaceous control and template replication?
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Structural and Biochemical Changes in Salicylic-Acid-Treated Date Palm Roots Challenged with<i>Fusarium oxysporum</i>f. sp.<i>albedinis</i>
No full textHistochemical and ultrastructural analyses were carried out to assess structural and biochemical changes in date palm roots pretreated with salicylic acid (SA) then inoculated withFusarium oxysporumf. sp.albedinis(Foa). Flavonoids, induced proteins, and peroxidase activity were revealed in root tissues of SA-treated plants after challenge by Foa. These reactions were closely associated with plant resistance to Foa. Host reactions induced after inoculation of SA-treated plants with Foa included the plugging of intercellular spaces, the deposition of electron-dense materials at the sites of pathogen penetration, and several damages to fungal cells. On the other hand, untreated inoculated plants showed marked cell wall degradation and total cytoplasm disorganization, indicating the protective effects provided by salicylic acid in treated plants.</jats:p
Induction of defense genes and secondary metabolites in saskatoons (Amelanchier alnifolia Nutt.) in response to Entomosporium mespili using jasmonic acid and Canada milkvetch extracts
No full textEntomosporium leaf and berry spot represent the most important disease of saskatoons (Amelanchier alnifolia Nutt.). This disease, caused by the ascomycete Entomosporium mespili (D.C.) Sacc., is difficult to control via conventional methods and no known saskatoon cultivar carries resistance to this pathogen. The aim of the present study was to enhance existing and induced defense responses of saskatoons using two host defense inducers, namely jasmonic acid and an extract from Canada milkvetch on two saskatoon cultivars, Smoky and Martin. Both inducers exhibited an ability to differentially induce the synthesis/accumulation of defense-related genes including those encoding for PR-1, PR-2, PR-5, LOX and PAL. Pre-treatment of saskatoon leaves with these inducers reduced the disease levels especially when applied to the moderately susceptible cultivar Martin. An accumulation of various hydroxycinnamic acid and proanthocyanidin derivatives also correlated with the disease levels recorded on both cultivars. Results are discussed on the basis of the induced pathways in an attempt to lay the ground for a better understanding of this hostpathogen interaction. In the meantime,wehave shown that the use of defense enhancers may be useful in integrated management strategies to control entomosporium leaf and berry spot in saskatoons spot in saskatoons.Fil: Wolski, Erika Alejandra. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata; ArgentinaFil: Henriquez, Maria A.. University Of Manitoba; CanadáFil: Adam, Lorne R.. University Of Manitoba; CanadáFil: Badawi, Mohamed. University Of Manitoba; CanadáFil: Andreu, Adriana Balbina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Biológicas; Argentina. Universidad Nacional de Mar del Plata; ArgentinaFil: Hadrami, Abdelbasset El . University Of Manitoba; CanadáFil: Daayf, Fouad. University Of Manitoba; Canad
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
The potential impact of pathogens on honey bee, Apis mellifera L., colonies and possibilities for their control
No full textExcessive honey bee colony losses all over the world are believed to be caused by multiple stressors. In this thesis, I characterized and quantified pathogen levels in honey bee colonies, studied their interactions with each other and with their associated parasite vectors, examined factors that influence their combined impacts on honey bees and developed methods to manage honey bee viruses so that colony losses can be minimized. My baseline study of virus prevalence and concentration in healthy and unhealthy (showing visible signs of disease) colonies in Canada showed that seven economically important viruses (DWV, BQCV, IAPV, KBV, SBV, ABPV, and CBPV) were all widely distributed in Canada. Differences in concentration and prevalence of some viruses were found between unhealthy and healthy colonies but these differences may have been due in part to seasonal or regional effects. Studies of the impact of viruses on worker bee populations over winter showed different factors were correlated with bee loss in different environments. Spring concentrations of DWV and mean abundance of Varroa (Varroa destructor) were positively correlated with bee loss and negatively correlated with spring population size in outdoor-wintered colonies. Fall concentration of IAPV was negatively correlated with spring population size of colonies in indoor-wintering environments but not in outdoor-environments. My study showed that it is important to consider location of sampling when associating pathogen loads with bee loss with Nosema and BQCV. Seasonal patterns of parasites and pathogens were characterized for each wintering methods (indoor and outdoor). My results revealed lower ABPV and Nosema ceranae prevalence and lower DWV concentration in genetically diverse than genetically similar colonies. I showed that within colony genetic diversity may be an important evolutionary adaptation to allow honey bees to defend against a wide range of diseases. In laboratory studies, I showed that feeding DWV to larvae in the absence of Varroa causes wing deformity and decreased survival rates of adult bees relative to bees not fed DWV. Finally, I showed that RNA silencing can be used to reduce DWV concentrations in immature and adult bees, reduce wing deformity in emerging adults, and increase their longevity relative to controls.May 201
Variations on the Author
No full text“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
No full textWe 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
Effects of glucan and eicosapetaeonoic acids on differential regulation on phenilpropanoids and mevalonic pathways during potato response to Phytophthora infestans
No full textThe effects of Phytophthora infestans glucans, eicosapentaenoic acid (EPA) and isolates of this pathogen, on the differential expression of eight genes from the phenylpropanoid and the mevalonate (Ac-MVA) pathways were analyzed in potato by semi-quantitative RT-PCR and qRT-PCR. The application of EPA had an elicitor effect in Russet Burbank (RB) and Defender (DF) in response to inoculation with a US8 isolate of P. infestans, thereby reducing symptoms of late blight. Such effect was associated with the expression of PAL-1 and PAL-2, since the latter occurred only when EPA was followed by inoculation, whereas these genes were down-regulated in individual treatments RB + EPA, RB + US8, DF + EPA, and DF + US8. The glucan fraction did not by itself suppress phenylpropanoid genes, but its combination with the pathogen resulted in a down-regulation of PAL-1, PAL-2 and CHS. The addition of the glucan fraction to the elicitor EPA, had a negative effect (RB + EPA + GL + US8) since plants showed higher disease symptoms than the ones pretreated with water then infected with US8, and in comparison with RB + EPA + US8 and RB + GL + US8. Exclusive up-regulation of 4CL in DF + US11 and of CHS in DF + EPA + GL + US8, DF + EPA + US11, DF + GL + US11 and DF + EPA + GL + US11, where late blight lesions were not detected, could be associated with potato protection against late blight. Along with previous findings in this pathosystem, these data suggest that genetic resistance in potato against P. infestans is not the result of isolated reactions against the pathogen, but rather the combination of many factors in-line with a polygenic/horizontal resistance.Fil: Henriquez, Maria A.. University Of Manitoba; CanadáFil: Wolski, Erika Alejandra. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Molina, Oscar I.. University Of Manitoba; CanadáFil: Adam, Lorne R.. University Of Manitoba; CanadáFil: Andreu, Adriana Balbina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Biológicas; Argentina. Universidad Nacional de Mar del Plata; ArgentinaFil: Daayf, Fouad. University Of Manitoba; Canad
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